False results caused by solvent impurity in tetrahydrofuran for maldi tof ms analysis of amines

NARCIS (Netherlands)

Lou, X.; Leenders, C.M.A.; van Onzen, Thuur; Bovee, R.A.A.; Van Dongen, J.L.J.; Vekemans, J.A.J.M.; Meijer, E. W.

Tetrahydrofuran (THF) is one of the most frequently used solvents in the MALDI TOF MS analysis of synthetic compounds. However, it should be used with caution because a trace amount of 4-hydroxybutanal (HBA) might be generated and accumulated in THF during storage. Since only a tiny amount of

Measuring and modelling of the combined thermodynamic promoting effect of tetrahydrofuran and cyclopentane on carbon dioxide hydrates

DEFF Research Database (Denmark)

Herslund, Peter Jørgensen; Daraboina, Nagu; Thomsen, Kaj

2014-01-01

This work documents both experimental data, and by thermodynamic modelling, the synergistic effect occurring in promoted carbon dioxide hydrate systems at the simultaneous presence of tetrahydrofuran and cyclopentane.Cyclopentane has previously been considered a reference among gas hydrate promot...

Simulating the synthesis and thermodynamic characteristics of the desolvation of lanthanide borohydride tris-Tetrahydrofuranates

Science.gov (United States)

Gafurov, B. A.; Mirsaidov, I. U.; Nasrulloeva, D. Kh.; Badalov, A.

2013-10-01

Lanthanide borohydride tris-tetrahydrofuranates (Ln(BH4) · 3THF, where THF is tetrahydrofuran and Ln is La, Nd, Sm, Gd, Er, Yb, and Lu) is synthesized via the exchange reaction of lanthanide(III) chloride and sodium borohydride in THF. It is found that synthesis proceeds according to a stepwise mechanism and the product of the reaction (lanthanide borohydride) initiates the process. The two-step character of the desolvation of Ln(BH4)3 · 3THF under steady-state conditions in the temperature range of 300 to 400 K is determined through X-ray phase and chemical analyses, tensiometry, and gas volumetry. It is established that one mole and then two moles of THF are removed from the initial sample at the first and second steps, respectively. Equations for barograms are obtained and the thermodynamic characteristics of desolvation of Ln(BH4)3 · 3THF under study are calculated. Gibbs energy values of the stages of process are determined semi-empirically. The law of its change for the entire series of Ln(BH4)3 · 3THF is determined with the emergence of the tetrad effect.

Third derivative thermodynamic quantities of aqueous tetrahydrofuran at 25 degrees C

DEFF Research Database (Denmark)

Westh, Peter; Yoshida, Koh; Inaba, Akira

2015-01-01

–THF interaction functions, HETHF–THF, and SETHF–THF. Using the literature density data, the effect of THF on the excess partial molar volume of THF, VETHF–THF, was also evaluated. Furthermore, we directly determined the partial molar entropy-volume cross fluctuation density of THF, View the MathML sourceδ......We measured the excess chemical potential, μΕTHF, the excess partial molar enthalpy and entropy of solute tetrahydrofuran (THF), HETHF and SETHF, in THF–H2O at 25 °C. Using these second derivatives of G, we graphically evaluated the third derivative quantities; the enthalpic, entropic THF...

1,1,1-Tris(dimethylamino-2-[tris(dimethylaminophosphoranylidene]diphosphinium tetraphenylborate tetrahydrofuran monosolvate

Directory of Open Access Journals (Sweden)

Bobby D. Ellis

2014-06-01

Full Text Available In the tetrahydrofuran solvate of the title salt, C12H36N6P3+·C24H20B−·C4H8O, the cation features short P—P bond lengths [2.1111 (11 and 2.1364 (10 Å] and a distinctly bent P—P—P angle [104.67 (4°] that confirm that the molecule is not allene-like. In the crystal, the solvent molecule is linked to the cation via a weak C—H...O hydrogen bond.

Synthesis of diastereomerically and enantiomerically pure 2,3-disubstituted tetrahydrofurans using a sulfoxonium ylide.

Science.gov (United States)

Schomaker, Jennifer M; Pulgam, Veera Reddy; Borhan, Babak

2004-10-27

Nucleophilic substitution reactions of 2,3-epoxy alcohols, easily prepared via Sharpless asymmetric epoxidation chemistry, offer access to a wide variety of enantiomerically pure compounds. In this communication, we describe the use of a Payne rearrangement to control regioselectivity in the ring-opening of a series of 2,3-epoxy alcohols with dimethylsulfoxonium methylide to yield diastereomerically and/or enantiomerically pure disubstituted tetrahydrofuran rings. The factors influencing the success and substitution pattern of the THF ring products are discussed, including steric, electronic, and solvent effects.

Differential cross sections for electron-impact vibrational-excitation of tetrahydrofuran at intermediate impact energies

Energy Technology Data Exchange (ETDEWEB)

Do, T. P. T. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); School of Education, Can Tho University, Campus II, 3/2 Street, Xuan Khanh, Ninh Kieu, Can Tho City (Viet Nam); Duque, H. V. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Konovalov, D. A.; White, R. D. [College of Science, Technology and Engineering, James Cook University, Townsville (Australia); Brunger, M. J., E-mail: michael.brunger@flinders.edu.au, E-mail: darryl.jones@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); Jones, D. B., E-mail: michael.brunger@flinders.edu.au, E-mail: darryl.jones@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia)

2015-03-28

We report differential cross sections (DCSs) for electron-impact vibrational-excitation of tetrahydrofuran, at intermediate incident electron energies (15-50 eV) and over the 10°-90° scattered electron angular range. These measurements extend the available DCS data for vibrational excitation for this species, which have previously been obtained at lower incident electron energies (≤20 eV). Where possible, our data are compared to the earlier measurements in the overlapping energy ranges. Here, quite good agreement was generally observed where the measurements overlapped.

The melting curve of tetrahydrofuran hydrate in D2O

International Nuclear Information System (INIS)

Hanley, H.J.M.; Meyers, G.J.; White, J.W.; Sloan, E.D.

1989-01-01

Melting points for the tetrahydrofuran/D 2 O hydrate in equilibrium with the air-saturated liquid at atmospheric pressure are reported. The melting points were measured by monitoring the absorbance of the solution. Overall, the melting-point phase boundary curve is about 2.5 K greater than the corresponding curve for the H 2 O hydrate, with a congruent melting temperature of 281 ± 0.5 K at a D 2 O mole fraction of 0.936. The phase boundary is predicted to within 5% if the assumption is made that the THF occupancy in the D 2 O and H 2 O hydrates is the same. The authors measure an occupancy of 99.9%. The chemical potential of the empty lattice in D 2 O is estimated to be 5% greater than in H 2 O

Conductivity hysteresis in polymer electrolytes incorporating poly(tetrahydrofuran)

Energy Technology Data Exchange (ETDEWEB)

Akbulut, Ozge; Taniguchi, Ikuo; Mayes, Anne M. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA (United States); Kumar, Sundeep; Shao-Horn, Yang [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA (United States)

2007-01-01

Conductivity hysteresis and room temperature ionic conductivities >10{sup -3}S/cm were recently reported for electrolytes prepared from blends of an amphiphilic comb copolymer, poly[2,5,8,11,14-pentaoxapentadecamethylene (5-hexadecyloxy-1,3-phenylene)] (polymer I), and a linear multiblock copolymer, poly(oligotetrahydrofuran-co-dodecamethylene) (polymer II), following thermal treatment [F. Chia, Y. Zheng, J. Liu, N. Reeves, G. Ungar, P.V. Wright, Electrochim. Acta 43 (2003) 1939]. To investigate the origin of these effects, polymers I and II were synthesized in this work, and the conductivity and thermal properties of the individual polymers were investigated. AC impedance measurements were conducted on I and II doped with LiBF{sub 4} or LiClO{sub 4} during gradual heating to 110{sup o}C and slow cooling to room temperature. Significant conductivity hysteresis was seen for polymer II, and was similarly observed for poly(tetrahydrofuran) (PTHF) homopolymer at equivalent doping levels. From thermogravimetric analysis (TGA), gel permeation chromatography (GPC) and {sup 1}H NMR spectroscopy, both polymer II and PTHF were found to partially decompose to THF during heat treatment, resulting in a self-plasticizing effect on conductivity. (author)

Properties of LiBF4 and LiAsF6 solutions in mixtures of tetrahydrofuran and 2-methyltetrahydrofuran

International Nuclear Information System (INIS)

Plakhotnik, A.V.; Tovmash, N.F.; Mishustin, A.I.; Kokunov, Yu.V.

1993-01-01

Solutions of lithium tetrafluoroborate and hexafluoroarsenate in mixtures of tetrahydrofuran and 2-methyltetrahydrofuran were studies by the methods of conductometry, densimetry, viscosimetry and measurement of spin-lattice relaxation rate on 7 Li nuclei. Considerable ifluence of anion nature was ascertained. Assumptions are made on the presence of cooperative interaction involving formation of the structures from solvent molecules and salt ions

Kinetic of formation for single carbon dioxide and mixed carbon dioxide and tetrahydrofuran hydrates in water and sodium chloride aqueous solution

NARCIS (Netherlands)

Sabil, K.M.; Duarte, A.R.C.; Zevenbergen, J.F.; Ahmad, M.M.; Yusup, S.; Omar, A.A.; Peters, C.J.

2010-01-01

A laboratory-scale reactor system is built and operated to measure the kinetic of formation for single and mixed carbon dioxide-tetrahydrofuran hydrates. The T-cycle method, which is used to collect the kinetic data, is briefly discussed. For single carbon dioxide hydrate, the induction time

An (e, 2e + ion) study of low-energy electron-impact ionization and fragmentation of tetrahydrofuran with high mass and energy resolutions

Science.gov (United States)

Ren, Xueguang; Pflüger, Thomas; Weyland, Marvin; Baek, Woon Yoon; Rabus, Hans; Ullrich, Joachim; Dorn, Alexander

2014-10-01

We study the low-energy (E0 = 26 eV) electron-impact induced ionization and fragmentation of tetrahydrofuran using a reaction microscope. All three final-state charged particles, i.e., two outgoing electrons and one fragment ion, are detected in triple coincidence such that the momentum vectors and, consequently, the kinetic energies for charged reaction products are determined. The ionic fragments are clearly identified in the experiment with a mass resolution of 1 amu. The fragmentation pathways of tetrahydrofuran are investigated by measuring the ion kinetic energy spectra and the binding energy spectra where an energy resolution of 1.5 eV has been achieved using the recently developed photoemission electron source. Here, we will discuss the fragmentation reactions for the cations C4H8O+, C4H7O+, C2H3O+, C3H_6^+, C3H_5^+, C3H_3^+, CH3O+, CHO+, and C2H_3^+.

Modelling of tetrahydrofuran promoted gas hydrate systems for carbon dioxide capture processes

DEFF Research Database (Denmark)

Herslund, Peter Jørgensen; Thomsen, Kaj; Abildskov, Jens

2014-01-01

A thermodynamic study of a novel gas hydrate based CO2 capture process is presented.•Model predicts this process unsuitable for CO2 capture from power station flue gases. A thermodynamic modelling study of both fluid phase behaviour and hydrate phase behaviour is presented for the quaternary system...... of water, tetrahydrofuran, carbon dioxide and nitrogen. The applied model incorporates the Cubic-Plus-Association (CPA) equation of state for the fluid phase description and the van der Waals-Platteeuw hydrate model for the solid (hydrate) phase. Six binary pairs are studied for their fluid phase behaviour...... accurate descriptions of both fluid- and hydrate phase equilibria in the studied system and its subsystems. The developed model is applied to simulate two simplified, gas hydrate-based processes for post-combustion carbon dioxide capture from power station flue gases. The first process, an unpromoted...

Effect tetrahydrofuran as solvent in the synthesis of mullite by the Pechini

International Nuclear Information System (INIS)

Braga, A.N.S.; Santos, V.B.; Simoes, V.N.; Neves, G.A.; Lira, H.L.; Menezes, R.R.

2016-01-01

Mullite has been considered interesting in recent decades, due to its properties. The reaction mechanisms in the mullite formation may vary according to the precursor and the methods employed. In order to get mullite by a promising chemical synthesis and understudied in its production, this paper aims to synthesize mullite by Pechini method. We investigated the mullite crystallization kinetics from use of tetrahydrofuran as solvent. The samples were characterized by diffraction of X-ray (XRD), thermal analysis and scanning electron microscopy (SEM). The XRD results showed the formation of mullite, but together with the alpha alumina phase. Thermal analysis confirmed the disruption of the polymer chain prior to the formation of crystalline phases, with a total weight loss of 97%. The SEM showed a morphology consists of large aggregates, damaging the properties of refractory and performance of the material. (author)

Application of the cubic-plus-association (CPA) equation of state to model the fluid phase behaviour of binary mixtures of water and tetrahydrofuran

DEFF Research Database (Denmark)

Herslund, Peter Jørgensen; Thomsen, Kaj; Abildskov, Jens

2013-01-01

The complex fluid phase behaviour, of the binary system comprised of water and tetrahydrofuran (THF) is modelled by use of the cubic-plus-association (CPA) equation of state. A total of seven modelling approaches are analysed, differing only in their way of describing THF and its interactions...

Fragmentation of tetrahydrofuran molecules by H(+), C(+), and O(+) collisions at the incident energy range of 25-1000 eV.

Science.gov (United States)

Wasowicz, Tomasz J; Pranszke, Bogusław

2015-01-29

We have studied fragmentation processes of the gas-phase tetrahydrofuran (THF) molecules in collisions with the H(+), C(+), and O(+) cations. The collision energies have been varied between 25 and 1000 eV and thus covered a velocity range from 10 to 440 km/s. The following excited neutral fragments of THF have been observed: the atomic hydrogen H(n), n = 4-9, carbon atoms in the 2p3s (1)P1, 2p4p (1)D2, and 2p4p (3)P states and vibrationally and rotationally excited diatomic CH fragments in the A(2)Δ and B(2)Σ(-) states. Fragmentation yields of these excited fragments have been measured as functions of the projectile energy (velocity). Our results show that the fragmentation mechanism depends on the projectile cations and is dominated by electron transfer from tetrahydrofuran molecules to cations. It has been additionally hypothesized that in the C(+)+THF collisions a [C-C4H8O](+) complex is formed prior to dissociation. The possible reaction channels involved in fragmentation of THF under the H(+), C(+), and O(+) cations impact are also discussed.

The effect of stirring on the heterogeneous nucleation of water and of clathrates of tetrahydrofuran/water mixtures

Directory of Open Access Journals (Sweden)

P.W. Wilson

2016-03-01

Full Text Available The statistics of liquid-to-crystal nucleation are measured for both water and for clathrate-forming mixtures of tetrahydrofuran (THF and water using an automatic lag time apparatus (ALTA. We measure the nucleation temperature using this apparatus in which a single sample is repeatedly cooled, nucleated and thawed. The effect of stirring on nucleation has been evaluated numerically and is discussed. We find that stirring of the solution makes no difference to the nucleation temperature of a given solution in a given tube.

Successful bioaugmentation of an activated sludge reactor with Rhodococcus sp. YYL for efficient tetrahydrofuran degradation

International Nuclear Information System (INIS)

Yao, Yanlai; Lu, Zhenmei; Zhu, Fengxiang; Min, Hang; Bian, Caimiao

2013-01-01

Highlights: • Rhodococcus sp. YYL is an efficient tetrahydrofuran-degrading strain. • Strain YYL was used to augment an activated sludge system for THF degradation. • Successful bioaugmentation was achieved only by coinoculation of strain YYL and the two bacilli. • Successful bioaugmentation of the system resulted in efficient THF degradation. -- Abstract: The exchange of tetrahydrofuran (THF)-containing wastewater should significantly affect the performance of an activated sludge system. In this study, the feasibility of using THF-degrading Rhodococcus sp. strain YYL to bioaugment an activated sludge system treating THF wastewater was explored. As indicated by a DGGE analysis, strain YYL alone could not dominate the system, with the concentration of mixed liquor suspended solids (MLSS) decreasing to nearly half of the initial concentration after 45 d, and the microbial diversity was found to be significantly reduced. However, after the reactor was augmented with the mixed culture of strain YYL and two bacilli initially coexisting in the enriched isolation source, strain YYL quickly became dominant in the system and was incorporated into the activated sludge. The concentration of MLSS increased from 2.1 g/L to 7.3 g/L in 20 d, and the efficiency of THF removal from the system was remarkably improved. After the successful bioaugmentation, more than 95% of THF was completely removed from the wastewater when 20 mM THF was continuously loaded into the system. In conclusion, our research first demonstrates that bioaugmentation of activated sludge system for THF degradation is feasible but that successful bioaugmentation should utilize a THF-degrading mixed culture as the inoculum, in which the two bacilli might help strain YYL colonize in activated sludge by co-aggregation

Short-chain grafting of tetrahydrofuran and 1,4-dioxane cycles on vinylchloride-maleic anhydride copolymer

Directory of Open Access Journals (Sweden)

2009-01-01

Full Text Available Mass increase of vinylchloride-maleic anhydride (VC-MA copolymer samples aged in tetrahydrofuran (THF or in 1,4-dioxane results from chemical interaction of VC-MA macromolecules with 1,4-dioxane or THF. Microstructure of the products of such modification was proved by infrared spectroscopy (IR- and nuclear magnetic resonance spectroscopy (13C NMR and 1H NMR. Mechanism of modification has been proposed. The results of microstructure research of VC-MA samples aged in THF and in 1,4-dioxane coincide with already known data on the reactions of opening of these and other oxygen-containing cycles under mild conditions.

The role of electron-impact vibrational excitation in electron transport through gaseous tetrahydrofuran

Energy Technology Data Exchange (ETDEWEB)

Duque, H. V. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Do, T. P. T. [School of Education, Can Tho University, Campus II, 3/2 Street, Xuan Khanh, Ninh Kieu, Can Tho City (Viet Nam); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Konovalov, D. A.; White, R. D. [College of Science, Technology and Engineering, James Cook University, Townsville (Australia); Brunger, M. J., E-mail: michael.brunger@flinders.edu.au, E-mail: darryl.jones@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); Jones, D. B., E-mail: michael.brunger@flinders.edu.au, E-mail: darryl.jones@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia)

2015-03-28

In this paper, we report newly derived integral cross sections (ICSs) for electron impact vibrational excitation of tetrahydrofuran (THF) at intermediate impact energies. These cross sections extend the currently available data from 20 to 50 eV. Further, they indicate that the previously recommended THF ICS set [Garland et al., Phys. Rev. A 88, 062712 (2013)] underestimated the strength of the electron-impact vibrational excitation processes. Thus, that recommended vibrational cross section set is revised to address those deficiencies. Electron swarm transport properties were calculated with the amended vibrational cross section set, to quantify the role of electron-driven vibrational excitation in describing the macroscopic swarm phenomena. Here, significant differences of up to 17% in the transport coefficients were observed between the calculations performed using the original and revised cross section sets for vibrational excitation.

Reactions of UCl/sub 3/(THF)/sub x/ (THF=tetrahydrofuran) with poly(pyrazolyl) borates and sodium cyclopentadienide

Energy Technology Data Exchange (ETDEWEB)

Santos, I; Marques, N; Pires de Matos, A

1986-08-01

Reactions of the title compound with different stoichiometries of KH/sub n/BL/sub 4-n/ (where n=1,2 and L=3,5-dimethylpyrazolyl) have been studied and the compounds UCl/sub 2/H/sub 2/BL/sub 2/ and UCl/sub 2/HBL/sub 3/ identified. The preparation of UCl/sub 2/H/sub 2/BL'/sub 2/py (L'=pyrazolyl, py=pyridine) is reported. The reactivity of UCl/sub 2/H/sub 2/BL'/sub 2/THF with sodium cyclopentadienide in tetrahydrofuran and toluene has been studied.

Direct catalytic conversion of brown seaweed-derived alginic acid to furfural using 12-tungstophosphoric acid catalyst in tetrahydrofuran/water co-solvent

International Nuclear Information System (INIS)

Park, Geonu; Jeon, Wonjin; Ban, Chunghyeon; Woo, Hee Chul; Kim, Do Heui

2016-01-01

Highlights: • Furfural was produced by catalytic conversion of macroalgae-derived alginic acid. • 12-Tungstophosphoric acid (H_3PW_1_2O_4_0) showed remarkable catalytic performance. • Tetrahydrofuran (THF) as a reaction medium significantly enhanced production of furfural. - Abstract: Furfural, a biomass-derived platform chemical, was produced by acid-catalyzed reaction of alginic acid extracted from brown seaweed. Three acid catalysts, H_2SO_4, Amberlyst15 and 12-tungstophosphoric acid (H_3PW_1_2O_4_0), were compared to evaluate their catalytic performance for the alginic acid conversion. The H_3PW_1_2O_4_0 catalyst showed the highest catalytic activity, yielding the maximum furfural yield (33.8%) at 180 °C for 30 min in tetrahydrofuran/water co-solvent. Higher reaction temperature promoted the conversion of alginic acid to furfural, but the transformation of furfural to humin was also accelerated. To our knowledge, this is the highest furfural yield among studies about the direct catalytic conversion of alginic acid. Furthermore, products distribution with time-on-stream was investigated in detail, which led us to propose a reaction pathway.

Phase equilibria and excess molar volumes of tetrahydrofuran (1) + deuterium oxide (2)

International Nuclear Information System (INIS)

Lejcek, P.; Matous, J.; Novak, J.P.; Pick, J.

1975-01-01

Vapour + liquid equilibrium at 313.15 and 333.15K, liquid + liquid equilibrium throughout the whole region of limited miscibility, and excess molar volumes at 298.15K have been studied for tetrahydrofuran + deuterium oxide. The mixtures show large positive deviations from Raoult's law and a closed loop of limited miscibility. The modified Redlich-Kister equation has been used for the correlation of the vapour + liquid equilibrium. The computation has been carried out according to a recently proposed procedure which makes it possible to obtain such constants of the correlation relation which are not inconsistent with physical reality, i.e. with the complete miscibility (partial delta 2 G/deltax 1 2 >0) under experimental conditions. Thermodynamic consistency was checked by the classical Redlich-Kister test and the one proposed by Ulrichson and Stevenson. Excess molar volumes are negative at all compositions with a point of inflexion in the water-rich region which indicates the extremes in partial molar volumes. (author)

Synergistic Diazo-OH Insertion/Conia-Ene Cascade Catalysis for the Stereoselective Synthesis of γ-Butyrolactones and Tetrahydrofurans.

Science.gov (United States)

Hunter, Arianne C; Schlitzer, Steven C; Sharma, Indrajeet

2016-11-02

A novel and highly efficient diazo-OH insertion/Conia-ene cascade reaction of readily available homopropargylic acids and alcohols with diazo carbonyl compounds is described. The cascade reaction involves a synergistic Rh/Ag/Au catalyst cocktail and proceeds instantly with a variety of substituted diazo compounds and acids/alcohols to provide functionalized γ-butyrolactones and tetrahydrofurans with complete regio- and stereoselectivity. The unprecedented rate-enhancement, complete stereoselectivity, and the enabling of new Conia-ene cyclizations suggest a concerted [4+1]-cycloaddition reaction pathway under synergistic (Rh/Ag/Au)-catalysis conditions. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermodynamic promotion of carbon dioxide-clathrate hydrate formation by tetrahydrofuran, cyclopentane and their mixtures

DEFF Research Database (Denmark)

Herslund, Peter Jørgensen; Thomsen, Kaj; Abildskov, Jens

2013-01-01

Gas clathrate hydrate dissociation pressures are reported for mixtures of carbon dioxide, water and thermodynamic promoters forming structure II hydrates.Hydrate (H)-aqueous liquid (Lw)-vapour (V) equilibrium pressures for the ternary system composed of water, tetrahydrofuran (THF), and carbon....... It is shown that upon adding THF to the pure aqueous phase to form a 4mass percent solution, the equilibrium pressure of the formed hydrates may be lowered compared to the ternary system of water, cyclopentane and carbon dioxide. © 2013 Elsevier Ltd....... dioxide (CO2), with 5.0mole percent THF in the initial aqueous phase, are presented in the temperature range from 283.3K to 285.2K. At 283.3K, the three-phase equilibrium pressure is determined to be 0.61MPa (absolute pressure).Four-phase hydrate (H)-aqueous liquid (Lw)-organic liquid (La)-vapour (V...

A high selective cataluminescence sensor for the determination of tetrahydrofuran vapor

Science.gov (United States)

Cao, Xiaoan; Dai, Huimei; Chen, Suilin; Zeng, Jiayi; Zhang, Keke; Sun, Yan

2013-02-01

A novel tetrahydrofuran (THF) vapor sensor was designed based on the cataluminescence (CTL) of THF on nanosized γ-Al2O3/MgO (mol ratio = 1.5:1). SEM and XRD were applied for its characterization. We found that the CTL was strongly produced when THF vapor flowed through a nanosized Al-Mg mixed-metal oxide surface, while the CTL was weakly generated when THF vapor flowed through a single nanosized γ-Al2O3 or MgO surface. Quantitative analysis was performed at an optimal temperature of 279 °C, a wavelength of 460 nm and a flow rate of 360 mL min-1. The linear range of the CTL intensity versus concentrations of THF vapor was 1.0-3000 mL m-3 with a detection limit of 0.67 mL m-3. No (or only very low) interference was observed by formaldehyde, methanol, ethanol, benzene, toluene, ethyl acetate, ammonia, cyclohexane, chloroform, glycol armour ether, glycol ether, isopropyl ether and n-butyl ether or acetic acid. Since the response of the sensor was rapid and the system was easy to handle, we believe that the sensor has great potential for real-world use.

A Tetrahydrofuran-selective Optical Solvent Sensor Based on Solvatochromic Polydiacetylene

International Nuclear Information System (INIS)

Park, Dong-Hoon; Kim, Bubsung; Kim, Jong-Man

2016-01-01

Polydiacetylene (PDAs) have received great attention as colorimetric sensors since these conjugated polymers undergo a blue-to-red color change upon various chemical/biochemical and physical stimuli. PDAs have been reported to display thermochromism (heat), solvatochromism (solvent), mechanochromism (mechanical strain) as well as magnetochromism (magnetic force) electrochromism (electric current), and affinochromism (ligand-receptor interaction). The solvent induced color change of PDA is generally non-specific and irreversible. For instance, the PDA derived from 10,12-pentacosadiynoic acid (PCDA) undergoes a blue-to-red (or purple) color change upon exposure to many common organic solvents including tetrahydrofuran (THF), chloroform, dichloromethane, acetone, methanol (MeOH), ethyl acetate (EA), and diethyl ether. The results obtained from Raman spectral analysis suggests that exposure to THF causes the distortion of the backbone of the polymer main chain and some conformational changes in the aliphatic side chain. Solvatochromism of a PDA is closely related to the solubility of a diacetylene monomer. PDA undergoes a color change when the dissolution of unpolymerized monomers causes some void in the PDA supramolecules. Since PCDA-mBzA has a good solubility only in THF, colorimetric transition of PDA occurs only in response to THF. Since solubility of a diacetylene monomer can be manipulated by structural change of the monomer, we believe the strategy described in current investigation should be useful for the development of solvent-specific PDA sensor systems

A Tetrahydrofuran-selective Optical Solvent Sensor Based on Solvatochromic Polydiacetylene

Energy Technology Data Exchange (ETDEWEB)

Park, Dong-Hoon; Kim, Bubsung; Kim, Jong-Man [Hanyang University, Seoul (Korea, Republic of)

2016-06-15

Polydiacetylene (PDAs) have received great attention as colorimetric sensors since these conjugated polymers undergo a blue-to-red color change upon various chemical/biochemical and physical stimuli. PDAs have been reported to display thermochromism (heat), solvatochromism (solvent), mechanochromism (mechanical strain) as well as magnetochromism (magnetic force) electrochromism (electric current), and affinochromism (ligand-receptor interaction). The solvent induced color change of PDA is generally non-specific and irreversible. For instance, the PDA derived from 10,12-pentacosadiynoic acid (PCDA) undergoes a blue-to-red (or purple) color change upon exposure to many common organic solvents including tetrahydrofuran (THF), chloroform, dichloromethane, acetone, methanol (MeOH), ethyl acetate (EA), and diethyl ether. The results obtained from Raman spectral analysis suggests that exposure to THF causes the distortion of the backbone of the polymer main chain and some conformational changes in the aliphatic side chain. Solvatochromism of a PDA is closely related to the solubility of a diacetylene monomer. PDA undergoes a color change when the dissolution of unpolymerized monomers causes some void in the PDA supramolecules. Since PCDA-mBzA has a good solubility only in THF, colorimetric transition of PDA occurs only in response to THF. Since solubility of a diacetylene monomer can be manipulated by structural change of the monomer, we believe the strategy described in current investigation should be useful for the development of solvent-specific PDA sensor systems.

Towards CO2 sequestration and applications of CO2 hydrates: the effects of tetrahydrofuran on the phase equilibria of CO2 hydrates

International Nuclear Information System (INIS)

Khalik, M.S.; Peters, C.J.

2006-01-01

The increasing quantity of carbon dioxide (CO 2 ) in the atmosphere has caused widespread global concerns. Capturing CO 2 from its sources and stored it in the form of gas hydrates and application of CO 2 hydrates are among the proposed methods to overcome this problem. In order to make hydrate-based process more attractive, the use of cyclic ethers as promoters is suggested to reduce the required hydrate formation pressure and enhancing the corresponding kinetic rate. In the present work, tetrahydrofuran (THF) is chosen as a hydrate promoter, participating in forming hydrates and produces mixed hydrate together with CO 2 . The pressure and temperature ranges of hydrate stability region are carefully determined through phase equilibrium measurement of the ternary CO 2 , tetrahydrofuran (THF) and water systems. From the experimental results, it is confirmed that the presence of THF in CO 2 + water systems will extend the hydrate formation region to higher temperature at a constant pressure. The extension of the hydrate stability region is depended on the overall concentration of the ternary system. Moreover, four-phase equilibrium of H-Lw-Lv-V is observed in the system, which may be due to a liquid phase split. In the region where the four-phase equilibrium exists, the ternary system loses its concentration dependency of the hydrate equilibrium conditions. (Author)

Isothermal (vapour + liquid) equilibrium for binary mixtures of (tetrahydrofuran + 1,1,2,2-tetrachloroethane or tetrachloroethene) at nine temperatures

International Nuclear Information System (INIS)

Garriga, R.; Perez, P.; Gracia, M.

2006-01-01

Vapour pressures of (tetrahydrofuran + 1,1,2,2-tetrachloroethane, or tetrachloroethene) at nine temperatures between T = 283.15 K and T = 323.15 K were measured by a static method. The reduction of the vapour pressures data to obtain activity coefficients and excess molar Gibbs energies was carried out by fitting the vapour pressure data to the Redlich-Kister polynomial according to Barker's method. Excess molar volumes were also measured at T 298.15 K. A comparative analysis about the thermodynamic behaviour of both systems is performed, in terms of hydrogen bonding and electron-donor-acceptor interactions, as well as the resonance effect in tetrachloroethene

To the issue of temperature-dependent behavior of standard molar volumes of components in the binary system (water + tetrahydrofuran) at ambient pressure

International Nuclear Information System (INIS)

Ivanov, Evgeniy V.

2014-01-01

Graphical abstract: The standard molar volume of tetrahydrofuran (THF) in water, V THF ∘ (■), is a close-to-linear function of temperature and becomes increasingly appreciable with rising of the latter. Herewith the molar volume of pure THF, V THF (□), is retained to be larger, as compared to V THF ∘ , over all the temperature range studied. - Highlights: • Densities of aqueous THF at nine temperatures from (278.15 to 318.15) K were measured. • Temperature-dependent standard molar volumes of THF in water were calculated. • The analysis of excess standard molar volumes in the (water + THF) system was made. • The use of Redlich–Kister equation to obtain standard molar volumes is discussed. - Abstract: This report presents a comparative analysis of temperature-dependent data on density of both dilute aqueous solutions of tetrahydrofuran (THF) and dilute solutions of water in THF, as well as standard molar volumes of water or THF as a solute. For this purpose, new results on studying the volume-related properties of THF in a water-rich region at temperatures from (278.15 to 318.15) K, with a step of 5 K, and at the ambient pressure have been derived densimetrically. In discussion, some comments on previously published investigations, being related to temperature-dependent changes in the solution density and standard molar volumes of components of the system (water + THF), have been made

Hydrate phase equilibrium and structure for (methane + ethane + tetrahydrofuran + water) system

International Nuclear Information System (INIS)

Sun Changyu; Chen Guangjin; Zhang Lingwei

2010-01-01

The separation of methane and ethane through forming hydrate is a possible choice in natural gas, oil processing, or ethylene producing. The hydrate formation conditions of five groups of (methane + ethane) binary gas mixtures in the presence of 0.06 mole fraction tetrahydrofuran (THF) in water were obtained at temperatures ranging from (277.7 to 288.2) K. In most cases, the presence of THF in water can lower the hydrate formation pressure of (methane + ethane) remarkably. However, when the composition of ethane is as high as 0.832, it is more difficult to form hydrate than without THF system. Phase equilibrium model for hydrates containing THF was developed based on a two-step hydrate formation mechanism. The structure of hydrates formed from (methane + ethane + THF + water) system was also determined by Raman spectroscopy. When THF concentration in initial aqueous solution was only 0.06 mole fraction, the coexistence of structure I hydrate dominated by ethane and structure II hydrate dominated by THF in the hydrate sample was clearly demonstrated by Raman spectroscopic data. On the contrary, only structure II hydrate existed in the hydrate sample formed from (methane + ethane + THF + water) system when THF concentration in initial aqueous solution was increased to 0.10 mole fraction. It indicated that higher THF concentration inhibited the formation of structure I hydrate dominated by ethane and therefore lowered the trapping of ethane in hydrate. It implies a very promising method to increase the separation efficiency of methane and ethane.

Hydrogen Storage Capacity of Tetrahydrofuran and Tetra-N-Butylammonium Bromide Hydrates Under Favorable Thermodynamic Conditions

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Joshua T. Weissman

2017-08-01

Full Text Available An experimental study was conducted to evaluate the feasibility of employing binary hydrates as a medium for H2 storage. Two reagents, tetrahydrofuran (THF and tetra-n-butylammonium bromide (TBAB, which had been reported previously to have potential to form binary hydrates with H2 under favorable conditions (i.e., low pressures and high temperatures, were investigated using differential scanning calorimetry and Raman spectroscopy. A scale-up facility was employed to quantify the hydrogen storage capacity of THF binary hydrate. Gas chromatography (GC and pressure drop analyses indicated that the weight percentages of H2 in hydrate were less than 0.1%. The major conclusions of this investigation were: (1 H2 can be stored in binary hydrates at relatively modest pressures and temperatures which are probably feasible for transportation applications; and (2 the storage capacity of H2 in binary hydrate formed from aqueous solutions of THF over a concentration range extending from 2.78 to 8.34 mol % and at temperatures above 263 K and pressures below 11 MPa was <0.1 wt %.

1,3-Dioxolane, tetrahydrofuran, acetylacetone and dimethyl sulfoxide as solvents for non-aqueous vanadium acetylacetonate redox-flow-batteries

International Nuclear Information System (INIS)

Herr, T.; Noack, J.; Fischer, P.; Tübke, J.

2013-01-01

Highlights: • Four solvents were employed in a non-aqueous redox flow battery system. • Coulombic efficiencies of 85.9–98.5% and energy efficiencies of 26.6–43.6% were achieved. • Discharge power density was enhanced up to 0.080 mW cm −2 . • Solubility of V(acac) 3 was increased to 0.8 M compared to the acetonitrile system. -- Abstract: A non-aqueous vanadium acetylacetonate redox flow battery with different organic solvents and tetrabutylammonium hexafluorophosphate has been investigated. Cyclic voltammograms show three redox couples in 1,3-dioxolane, tetrahydrofuran, acetylacetone and two redox couples in dimethyl sulfoxide. Cell potentials between 2.21 and 2.61 V are measured, depending on the solvent used. Impedance Spectroscopy has been used to determine rate limiting step in the non-aqueous redox flow battery. Experiments in a charge–discharge test cell yielded coulombic and energy efficiencies of 85.9–98.5% and 26.6–43.6%, respectively

The quadrupoles and its formation constant in an electrolytic solution of lithium perchlorate in tetrahydrofuran plus formic acid, at 298.15 K

International Nuclear Information System (INIS)

Inocencio, A.A.; Almeida, E.T. de

1985-01-01

The condutance data for the electrolytic solutions of LiclO 4 in a mixture of tetrahydrofuran (THF) plus formic acid, indicate the existence of pairs, triple ions and quadrupoles. The association constantes K sub(a) and K sub(t) for the ion pairs and triple ions, respectively, have been included in a previous paper, where those experimental results have been published. Now, through an analysis accounting simultaneously for the pairs, triple ions and quadrupoles in the solution, the quadrupole formation constant K sub(q) has been calculated, together with K sub(a) and K sub(t). The activity coefficients have been obtained by means of the Debye-Huckel's theory, Stockes radii and solvation numbers have been estimated and the structure of the ionic aggregates discussed. (Author) [pt

Response Surface Methodology for Biodiesel Production Using Calcium Methoxide Catalyst Assisted with Tetrahydrofuran as Cosolvent

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Nichaonn Chumuang

2017-01-01

Full Text Available The present study was performed to optimize a heterogeneous calcium methoxide (Ca(OCH32 catalyzed transesterification process assisted with tetrahydrofuran (THF as a cosolvent for biodiesel production from waste cooking oil. Response surface methodology (RSM with a 5-level-4-factor central composite design was applied to investigate the effect of experimental factors on the percentage of fatty acid methyl ester (FAME conversion. A quadratic model with an analysis of variance obtained from the RSM is suggested for the prediction of FAME conversion and reveals that 99.43% of the observed variation is explained by the model. The optimum conditions obtained from the RSM were 2.83 wt% of catalyst concentration, 11.6 : 1 methanol-to-oil molar ratio, 100.14 min of reaction time, and 8.65% v/v of THF in methanol concentration. Under these conditions, the properties of the produced biodiesel satisfied the standard requirement. THF as cosolvent successfully decreased the catalyst concentration, methanol-to-oil molar ratio, and reaction time when compared with biodiesel production without cosolvent. The results are encouraging for the application of Ca(OCH32 assisted with THF as a cosolvent for environmentally friendly and sustainable biodiesel production.

Clarification of the volumetric properties of the (tetrahydrofuran + water) systems [J. Chem. Thermodyn. 41 (2009) 1382–1386]: Author’s statement

International Nuclear Information System (INIS)

Belandria, Veronica; Pimentel-Rodas, Alfredo; Mohammadi, Amir H.; Galicia-Luna, Luis A.; Richon, Dominique

2013-01-01

Highlights: ► New experimental density data are reported for the (THF + water) systems. ► A vibrating tube densimeter has been used to perform the measurements. ► A discussion is made on the reliability of the generated data and other questions raised in the literature. - Abstract: Although reliable and consistent volumetric data can be derived from density measurements, the greatest experimental difficulty and largest measurement errors often occur in the very dilute regions of concentration. Such data are of great interest in separation processes where a high degree of purity is required. In this communication, the densities of the (tetrahydrofuran + water) systems have been carefully investigated in dilute regions. A vibrating tube densimeter has been used to perform the measurements. A discussion is made on the reliability of the generated experimental data and the questions raised in the literature.

Organic liquids-responsive β-cyclodextrin-functionalized graphene-based fluorescence probe: label-free selective detection of tetrahydrofuran.

Science.gov (United States)

Hu, Huawen; Xin, John H; Hu, Hong; Wang, Xiaowen; Lu, Xinkun

2014-06-06

In this study, a label-free graphene-based fluorescence probe used for detection of volatile organic liquids was fabricated by a simple, efficient and low-cost method. To fabricate the probe, a bio-based β-cyclodextrin (β-CD) was firstly grafted on reduced graphene surfaces effectively and uniformly, as evidenced by various characterization techniques such as Ultraviolet/Visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The subsequent inclusion of Rhodamine B (RhB) into the inner cavities of the β-CD grafted on the graphene surfaces was achieved easily by a solution mixing method, which yielded the graphene-based fluorescent switch-on probe. In addition, the gradual and controllable quenching of RhB by Fluorescence Resonance Energy Transfer from RhB to graphene during the process of stepwise accommodation of the RhB molecules into the β-CD-functionalized graphene was investigated in depth. A wide range of organic solvents was examined using the as-fabricated fluorescence probe, which revealed the highest sensitivity to tetrahydrofuran with the detection limit of about 1.7 μg/mL. Some insight into the mechanism of the different responsive behaviors of the fluorescence sensor to the examined targets was also described.

Organic Liquids-Responsive β-Cyclodextrin-Functionalized Graphene-Based Fluorescence Probe: Label-Free Selective Detection of Tetrahydrofuran

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Huawen Hu

2014-06-01

Full Text Available In this study, a label-free graphene-based fluorescence probe used for detection of volatile organic liquids was fabricated by a simple, efficient and low-cost method. To fabricate the probe, a bio-based β-cyclodextrin (β-CD was firstly grafted on reduced graphene surfaces effectively and uniformly, as evidenced by various characterization techniques such as Ultraviolet/Visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The subsequent inclusion of Rhodamine B (RhB into the inner cavities of the β-CD grafted on the graphene surfaces was achieved easily by a solution mixing method, which yielded the graphene-based fluorescent switch-on probe. In addition, the gradual and controllable quenching of RhB by Fluorescence Resonance Energy Transfer from RhB to graphene during the process of stepwise accommodation of the RhB molecules into the β-CD-functionalized graphene was investigated in depth. A wide range of organic solvents was examined using the as-fabricated fluorescence probe, which revealed the highest sensitivity to tetrahydrofuran with the detection limit of about 1.7 μg/mL. Some insight into the mechanism of the different responsive behaviors of the fluorescence sensor to the examined targets was also described.

Reduction of uranium(IV) and its mixtures with an olefin or an alkyne in tetrahydrofuran solutions by solvated electrons

International Nuclear Information System (INIS)

Koulkes-Pujo, A.M.; Le Marechal, J.F.; Le Motais, B.; Folcher, G.

1985-01-01

The reduction of UCl 4 and its mixtures with different olefins (stilbene, St, diphenylethylene, DPE, acenaphtylene, Ac or with diphenylacetylene (DPA) was studied by pulse radiolysis of tetrahydrofuran (THF) solutions. U(III) was formed by U(IV) reaction either with the solvated electrons created by THF radiolysis or with the transitory anions St - and DPA - . In the latter case, the reaction proceeds via a first step leading to [St-U(IV)] - or [DPA-U(IV)] - . In the case of DPE - the first species, [DPE-U(IV)] - , does not lead to U(III) but is destroyed by THF(H) + giving DPE(H). and U(IV). Ac - does not react with U(IV). A mechanistic scheme of this electron attachment is discussed as well as its implication in catalytic hydrogenation of olefins in LiAlH 4 -UCl 4 solutions. It is concluded that the catalytic effect observed is rather the result of a hydride transfer from a uranium transient compound to the alkenes. 22 references, 8 figures, 1 table

Properties of LiBF[sub 4] and LiAsF[sub 6] solutions in mixtures of tetrahydrofuran and 2-methyltetrahydrofuran. Svojstva rastvorov LiBF[sub 4] i LiAsF[sub 6] v smesyakh tetragidrofurana i 2-metiltetragidrofurana

Energy Technology Data Exchange (ETDEWEB)

Plakhotnik, A V; Tovmash, N F; Mishustin, A I; Kokunov, Yu V [AN SSSR, Moscow (Russian Federation). Inst. Obshchej i Neorganicheskoj Khimii

1993-01-01

Solutions of lithium tetrafluoroborate and hexafluoroarsenate in mixtures of tetrahydrofuran and 2-methyltetrahydrofuran were studies by the methods of conductometry, densimetry, viscosimetry and measurement of spin-lattice relaxation rate on [sup 7]Li nuclei. Considerable ifluence of anion nature was ascertained. Assumptions are made on the presence of cooperative interaction involving formation of the structures from solvent molecules and salt ions.

Growth mode transition of tetrahydrofuran clathrate hydrates in the guest/host concentration boundary layer.

Science.gov (United States)

Sabase, Yuichiro; Nagashima, Kazushige

2009-11-19

Clathrate hydrates are known to form a thin film along a guest/host boundary. We present here the first report of tetrahydrofuran (THF) clathrate hydrate formation in a THF/water concentration boundary layer. We found that the THF-water system also forms a hydrate film separating the guest/host phases. The lateral growth rate of the film increases as supercooling increases. The thickness of the film at the growth tip decreases as supercooling and the lateral growth rate increase. These tendencies are consistent with reports of experiments for other hydrates and predictions of heat-transfer models. After film formation and slight melting, two types of growth modes are observed, depending on temperature T. At T = 3.0 degrees C, the film slowly thickens. The thickening rate is much lower than the lateral growth rate, as reported for other hydrates. At T agglomerate of small polycrystalline hydrates forms in each phase. Grain boundaries in the film and pore spaces in the agglomerate act as paths for permeation of each liquid. Timing when continuous nucleation starts is dominantly controlled by the time of initiation of liquid permeation through the film. Digital particle image velocimetry analysis of the agglomerate shows that it expands not by growth at the advancing front but rather by continuous nucleation in the interior. Expansion rates of the agglomerate tend to be higher for the cases of multipermeation paths in the film and the thinner film. We suppose that the growth mode transition to continuous nucleation is caused by the memory effect due to slight melting of the hydrate film.

Crystal structure of an unknown tetrahydrofuran solvate of tetrakis(μ3-cyanato-κ3N:N:Ntetrakis[(triphenylphosphane-κPsilver(I

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Peter Frenzel

2015-10-01

Full Text Available In the title compound, [{[(C6H53P]Ag}4{NCO}4], a distorted Ag4N4-heterocubane core is set up by four AgI ions being coordinated by the N atoms of the cyanato anions in a μ3-bridging mode. In addition, a triphenylphosphine ligand is datively bonded to each of the AgI ions. Intramolecular Ag...Ag distances as short as 3.133 (9 Å suggest the presence of argentophilic (d10...d10 interactions. Five moderate-to-weak C—H...O hydrogen-bonding interactions are observed in the crystal structure, spanning a three-dimensional network. A region of electron density was treated with the SQUEEZE procedure in PLATON [Spek (2015. Acta Cryst. C71, 9–18] following unsuccessful attempts to model it as being part of disordered tetrahydrofuran solvent molecules. The given chemical formula and other crystal data do not take into account these solvent molecules.

Quantitative determination of 1,4-dioxane and tetrahydrofuran in groundwater by solid phase extraction GC/MS/MS.

Science.gov (United States)

Isaacson, Carl; Mohr, Thomas K G; Field, Jennifer A

2006-12-01

Groundwater contamination by cyclic ethers, 1,4-dioxane (dioxane), a probable human carcinogen, and tetrahydrofuran (THF), a co-contaminant at many chlorinated solvent release sites, are a growing concern. Cyclic ethers are readily transported in groundwater, yet little is known about their fate in environmental systems. High water solubility coupled with low Henry's law constants and octanol-water partition coefficients make their removal from groundwater problematic for both remedial and analytical purposes. A solid-phase extraction (SPE) method based on activated carbon disks was developed for the quantitative determination of dioxane and THF. The method requires 80 mL samples and a total of 1.2 mL of solvent (acetone). The number of steps is minimized due to the "in-vial" elution of the disks. Average recoveries for dioxane and THF were 98% and 95%, respectively, with precision, as indicated by the relative standard deviation of <2% to 6%. The method quantitation limits are 0.31 microg/L for dioxane and 3.1 microg/L for THF. The method was demonstrated by analyzing groundwater samples for dioxane and THF collected during a single sampling campaign at a TCA-impacted site. Dioxane concentrations and areal extent of dioxane in groundwater were greater than those of either TCA or THF.

Properties of Electrospun Nanofibers of Multi-Block Copolymers of [Poly-ε-caprolactone-b-poly(tetrahydrofuran-co-ε-caprolactone]m Synthesized by Janus Polymerization

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Muhammad Ijaz Shah

2017-10-01

Full Text Available Novel biodegradable multiblock copolymers of [PCL-b-P(THF-co-CL]m with PCL fractions of 53.3 and 88.4 wt % were prepared by Janus polymerization of ε-caprolactone (CL and tetrahydrofuran (THF. Their electrospun mats were obtained with optimized parameters containing bead-free nanofibers whose diameters were between 290 and 520 nm. The mechanical properties of the nanofiber scaffolds were measured showing the tensile strength and strain at break of 8–10 MPa and 123–161%, respectively. Annealing improved their mechanical properties and their tensile strength and strain at break of the samples increased to 10–13 MPa and 267–338%, respectively. Due to the porous structure and crystallization in nanoscale confinement, the mechanical properties of the nanofiber scaffolds appeared as plastics, rather than as the elastomers observed in bulk thermal-molded film.

Deprotonation effect of tetrahydrofuran-2-carbonitrile buffer gas dopant in ion mobility spectrometry.

Science.gov (United States)

Fernandez-Maestre, Roberto; Meza-Morelos, Dairo; Wu, Ching

2016-06-15

When dopants are introduced into the buffer gas of an ion mobility spectrometer, spectra are simplified due to charge competition. We used electrospray ionization to inject tetrahydrofuran-2-carbonitrile (F, 2-furonitrile or 2-furancarbonitrile) as a buffer gas dopant into an ion mobility spectrometer coupled to a quadrupole mass spectrometer. Density functional theory was used for theoretical calculations of dopant-ion interaction energies and proton affinities, using the hybrid functional X3LYP/6-311++(d,p) with the Gaussian 09 program that accounts for the basis set superposition error; analytes structures and theoretical calculations with Gaussian were used to explain the behavior of the analytes upon interaction with F. When F was used as a dopant at concentrations below 1.5 mmol m(-3) in the buffer gas, ions were not observed for α-amino acids due to charge competition with the dopant; this deprotonation capability arises from the production of a dimer with a high formation energy that stabilized the positive charge and created steric hindrance that deterred the equilibrium with analyte ions. F could not completely strip other compounds of their charge because they either showed steric hindrance at the charge site that deterred the approach of the dopant (2,4-lutidine, and DTBP), formed intramolecular bonds that stabilized the positive charge (atenolol), had high proton affinity (2,4-lutidine, DTBP, valinol and atenolol), or were inherently ionic (tetraalkylammonium ions). This selective deprotonation suggests the use of F to simplify spectra of complex mixtures in ion mobility and mass spectrometry in metabolomics, proteomics and other studies that generate complex spectra with thousands of peaks. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Differential and integral electron scattering cross sections from tetrahydrofuran (THF) over a wide energy range: 1-10.000 eV

International Nuclear Information System (INIS)

Fuss, M.C.; Sanz, A.G.; Blanco, F.; Limao-Vieira, P.; Brunger, M.J.; Garcia, G.

2014-01-01

Tetrahydrofuran (THF, C 4 H 8 O) has a molecular structure that is similar to the ribose in the DNA backbone and is used as a surrogate of ribose to get electron scattering cross sections. Total, integral inelastic and integral and differential elastic cross sections have been calculated with the screening-corrected additivity rule (SCAR) method based on the independent atom model (IAM) for electron scattering from THF. Since the permanent dipole moment of THF enhances rotational excitation particularly at low energies and for small angles, an estimate of the rotational excitation cross section was also computed by assuming the interaction with a free electric dipole as an independent, additional process. Our theoretical results compare very favourably to the existing experimental data. Finally, a self-consistent set of integral and differential interaction cross-sections for the incident energy range 1 eV - 10 keV is established for use in our low energy particle track simulation (LEPTS). All cross section data are supplied numerically in tabulated form. (authors)

Effect tetrahydrofuran as solvent in the synthesis of mullite by the Pechini; Efeito do tetrahidrofurano como solvente na sintese de mulita pelo Metodo Pechini

Energy Technology Data Exchange (ETDEWEB)

Braga, A.N.S.; Santos, V.B. [Universidade Federal do Piaui (UFPI), Teresina, PI (Brazil); Simoes, V.N.; Neves, G.A.; Lira, H.L.; Menezes, R.R., E-mail: Aluskasimoes@homail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

2016-07-01

Mullite has been considered interesting in recent decades, due to its properties. The reaction mechanisms in the mullite formation may vary according to the precursor and the methods employed. In order to get mullite by a promising chemical synthesis and understudied in its production, this paper aims to synthesize mullite by Pechini method. We investigated the mullite crystallization kinetics from use of tetrahydrofuran as solvent. The samples were characterized by diffraction of X-ray (XRD), thermal analysis and scanning electron microscopy (SEM). The XRD results showed the formation of mullite, but together with the alpha alumina phase. Thermal analysis confirmed the disruption of the polymer chain prior to the formation of crystalline phases, with a total weight loss of 97%. The SEM showed a morphology consists of large aggregates, damaging the properties of refractory and performance of the material. (author)

Preparations, structures and properties of heterobimetallic complexes based on tetrahydrofuran-2,3,4,5-tetracarboxylate

International Nuclear Information System (INIS)

Jia, Tian-Jing; Li, Shu-Mu; Cao, Wei; Li, Li-Cun; Zheng, Xiang-Jun; Yuan, Da-Qiang

2013-01-01

Transition heterobimetallic metal-organic frameworks based on tetrahydrofuran-2,3,4,5-tetracarboxylicate (FTA), namely [M(H 2 O) 6 ][Cu 2 M(FTA) 2 (H 2 O) 2 ]·4H 2 O [M=Mn (1), Co (2)], and [CuZn(FTA)(H 2 O) 5 ]·H 2 O (3) have been synthesized and characterized. Single-crystal X-ray diffraction indicates that complexes 1 and 2 are isomorphic. In 1 and 2, FTA ligand links the metal ions to a 2-D wave-like negative-charged layer with a topology of (4;6 2 ) 2 (4;6 3 ;8 2 ) 2 (6). They possess 1-D channels with [M(H 2 O) 6 ] 2+ and lattice water molecules enclathrated. While in the complex 3, Cu 2+ and Zn 2+ ions are bridged by FTA to a 2-D neutral layer structure with a (8) 2 (8 4 ;12 2 ) topology. Magnetic properties of 1–3 were analyzed in connection with their structures, which show that there exist weak antiferromagnetic interactions between metal ions. - Graphical abstract: Three heterobimetallic MOFs were constructed through the size-selectivity of TFA coordination sites for different transition metal ions based on the concept of “Hard and Soft Acids and Bases”. Highlights: ► Complexes 1 and 3 contain 2-D wave-like negative-charged layers. ► Complex 2 is a 2-D neutral layer structure with a (8) 2 (8 4 ;12 2 ) topology. ► Complexes 1–3 are the first example of heterobimetallic MOFs based on FTA. ► The coordination sites of FTA show size-selectivity to metal ions

Preparations, structures and properties of heterobimetallic complexes based on tetrahydrofuran-2,3,4,5-tetracarboxylate

Energy Technology Data Exchange (ETDEWEB)

Jia, Tian-Jing; Li, Shu-Mu; Cao, Wei [College of Chemistry, Beijing Normal University, Beijing 100875 (China); Li, Li-Cun [College of Chemistry, Nankai University, Tianjin 300071 (China); Zheng, Xiang-Jun, E-mail: xjzheng@bnu.edu.cn [College of Chemistry, Beijing Normal University, Beijing 100875 (China); Yuan, Da-Qiang [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

2013-05-01

Transition heterobimetallic metal-organic frameworks based on tetrahydrofuran-2,3,4,5-tetracarboxylicate (FTA), namely [M(H₂O)₆][Cu₂M(FTA)₂(H₂O)₂]·4H₂O [M=Mn (1), Co (2)], and [CuZn(FTA)(H₂O)₅]·H₂O (3) have been synthesized and characterized. Single-crystal X-ray diffraction indicates that complexes 1 and 2 are isomorphic. In 1 and 2, FTA ligand links the metal ions to a 2-D wave-like negative-charged layer with a topology of (4;6²)₂(4;6³;8²)₂(6). They possess 1-D channels with [M(H₂O)₆]²⁺ and lattice water molecules enclathrated. While in the complex 3, Cu²⁺ and Zn²⁺ ions are bridged by FTA to a 2-D neutral layer structure with a (8)₂(8⁴;12²) topology. Magnetic properties of 1–3 were analyzed in connection with their structures, which show that there exist weak antiferromagnetic interactions between metal ions. - Graphical abstract: Three heterobimetallic MOFs were constructed through the size-selectivity of TFA coordination sites for different transition metal ions based on the concept of “Hard and Soft Acids and Bases”. Highlights: • Complexes 1 and 3 contain 2-D wave-like negative-charged layers. • Complex 2 is a 2-D neutral layer structure with a (8)₂(8⁴;12²) topology. • Complexes 1–3 are the first example of heterobimetallic MOFs based on FTA. • The coordination sites of FTA show size-selectivity to metal ions.

Volumetric properties of binary mixtures of N-ethylformamide with tetrahydrofuran, 2-butanone, and ethylacetate from T = (293.15 to 313.15) K

International Nuclear Information System (INIS)

Gadžurić, Slobodan; Nikolić, Aleksandar; Vraneš, Milan; Jović, Branislav; Damjanović, Marko; Dožić, Sanja

2012-01-01

Highlights: ► Densities of N-ethylformamide mixtures with ketones and esters were measured. ► Excess molar volumes were fitted to Redlich–Kister polynomial equation. ► Excess molar volumes are negative in the whole mole fraction range. ► Increase of the temperature has influence on N-ethylformamide self-association. ► Complex formation between the components was not observed. - Abstract: Densities of binary liquid mixtures of N-ethylformamide (NEF) with tetrahydrofuran (THF), 2-butanone (B), and ethylacetate (EA) were measured at temperatures from (293.15 to 313.15) K and at atmospheric pressure over the whole composition range. Excess molar volumes, V E , have been obtained from values of the experimental density and were fitted to the Redlich–Kister polynomial equation. The V E values for all three mixtures are negative over the entire composition and temperature ranges. The V E values become more negative as the temperature increases for all binary mixtures studied. Other volumetric properties, such as isobaric thermal expansion coefficients, partial molar volumes, apparent molar volumes, partial molar excess volumes and excess thermal expansions have been calculated.

Measurements of activity coefficients at infinite dilution of aliphatic and aromatic hydrocarbons, alcohols, thiophene, tetrahydrofuran, MTBE, and water in ionic liquid [BMIM][SCN] using GLC

International Nuclear Information System (INIS)

Domanska, Urszula; Laskowska, Marta

2009-01-01

The activity coefficients at infinite dilution, γ 13 ∞ for 32 solutes: alkanes, alken-1-es, alkyn-1-es, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, tetrahydrofuran, tert-butyl methyl ether, and water in the ionic liquid 1-butyl-3-methylimidazolium thiocyanate [BMIM][SCN] were determined by gas-liquid chromatography at the temperatures from 298.15 K to 368.15 K. The values of the partial molar excess enthalpies at infinite dilution ΔH 1 E,∞ were calculated from the experimental γ 13 ∞ values obtained over the temperature range. The selectivities for the hexane/benzene, cyclohexane/benzene, hexane/thiophene, and other separation problems were calculated from the γ 13 ∞ and compared to the other ionic liquids, N-methyl-2-pyrrolidinone, and sulfolane, taken from the recent literature. This work demonstrates that with chosen ionic liquid it is possible to separate different organic compounds with the highest selectivity, ever published

Molecular Interactions in 1,4-Dioxane, Tetrahydrofuran, and Ethyl Acetate Solutions of 1,1'-Bis(4-isopropyloxyacetylphenoxy)cyclohexane on Reological, Density, and Acoustic Behavior

Science.gov (United States)

Dhaduk, B. B.; Patel, Ch. B.; Parsania, P. H.

2017-12-01

Various thermo-acoustical parameters of 1,4-dioxane, tetrahydofuran and ethylacetae solutions of 1,1'-bis(4-isopropyloxyacetylphenoxy)cyclohexane were determined at different temperatures using density, viscosity and ultrasonic speed and correlated with concentration. Linear increase of ultrasonic speed, specific acoustical impedance, Rao's molar sound function, Van der Waals constant and free volume with concentration C and decreased with temperature. Linear decrease of adiabatic compressibility, internal pressure, intermolecular free path length, classical absorption coefficient, and viscous relaxation time with concentration and increased with temperature indicated existence of strong molecular interactions in solutions and further supported by positive values of solvation number. Gibbs free energy of activation decreased with C in all three systems. It is decreased with T in 1,4-dioxane, while increased in tetrahydrofuran and ethyl acetate. Both enthalpy of activation and entropy of activation are increased gradually with C in 1,4-dioxane, while they are negative and remained practically independent of concentration in 1,4-dioxane and tetrahydofuran systems.

Cyclopentadienyl complexes of uranium(IV) chlorides. Crystal structures of trichloro(eta5-cyclopentadienyl)bis(triphenylphosphine oxide)uranium(IV) tetrahydrofuran solvate and of trichloro(eta5-cyclopentadienyl)bis(hexamethylphosphoramide)uranium(IV)

International Nuclear Information System (INIS)

Bagnall, K.W.; De Paoli, G.

1984-01-01

The crystal and molecular structures of [U(cp)Cl 3 (PPh 3 O) 2 ].thf (thf = tetrahydrofuran) (1) and [U(cp)Cl 3 (P(NMe 2 ) 3 O) 2 ] (cp = eta 5 -cyclopentadienyl) (2) have been determined from three-dimensional X-ray diffraction data. The results are presented. In both compounds the uranium atom is octahedrally co-ordinated with the two neutral ligands [PPh 3 O and P(NMe 2 ) 3 O] in cis positions; the chlorine atoms are in the mer arrangement and the cyclopentadienyl group is trans to one neutral ligand. The appearance of cis octahedral geometry in complexes of the type [U(cp)Cl 3 L 2 ] is discussed in terms of the operation of a possible trans effect. (author)

On interfacial properties of tetrahydrofuran: Atomistic and coarse-grained models from molecular dynamics simulation

Energy Technology Data Exchange (ETDEWEB)

Garrido, J. M. [Departamento de Ingeniería Química, Universidad de Concepción, POB 160-C Concepción (Chile); Algaba, J.; Blas, F. J., E-mail: felipe@uhu.es [Laboratorio de Simulación Molecular y Química Computacional, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Física Aplicada, Universidad de Huelva, 21007 Huelva (Spain); Míguez, J. M. [Laboratoire des Fluides Complexes et Leurs Reservoirs, Université de Pau et des Pays de l’Adour, CNRS, TOTAL–UMR 5150, Avenue de l’Université, B.P. 1155, Pau F-64013 (France); Departamento de Física Aplicada, Universidade de Vigo, E36310 Vigo (Spain); Mendiboure, B. [Laboratoire des Fluides Complexes et Leurs Reservoirs, Université de Pau et des Pays de l’Adour, CNRS, TOTAL–UMR 5150, Avenue de l’Université, B.P. 1155, Pau F-64013 (France); Moreno-Ventas Bravo, A. I. [Laboratorio de Simulación Molecular y Química Computacional, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Geología, Universidad de Huelva, 21007 Huelva (Spain); Piñeiro, M. M. [Departamento de Física Aplicada, Universidade de Vigo, E36310 Vigo (Spain)

2016-04-14

We have determined the interfacial properties of tetrahydrofuran (THF) from direct simulation of the vapor-liquid interface. The molecules are modeled using six different molecular models, three of them based on the united-atom approach and the other three based on a coarse-grained (CG) approach. In the first case, THF is modeled using the transferable parameters potential functions approach proposed by Chandrasekhar and Jorgensen [J. Chem. Phys. 77, 5073 (1982)] and a new parametrization of the TraPPE force fields for cyclic alkanes and ethers [S. J. Keasler et al., J. Phys. Chem. B 115, 11234 (2012)]. In both cases, dispersive and coulombic intermolecular interactions are explicitly taken into account. In the second case, THF is modeled as a single sphere, a diatomic molecule, and a ring formed from three Mie monomers according to the SAFT-γ Mie top-down approach [V. Papaioannou et al., J. Chem. Phys. 140, 054107 (2014)]. Simulations were performed in the molecular dynamics canonical ensemble and the vapor-liquid surface tension is evaluated from the normal and tangential components of the pressure tensor along the simulation box. In addition to the surface tension, we have also obtained density profiles, coexistence densities, critical temperature, density, and pressure, and interfacial thickness as functions of temperature, paying special attention to the comparison between the estimations obtained from different models and literature experimental data. The simulation results obtained from the three CG models as described by the SAFT-γ Mie approach are able to predict accurately the vapor-liquid phase envelope of THF, in excellent agreement with estimations obtained from TraPPE model and experimental data in the whole range of coexistence. However, Chandrasekhar and Jorgensen model presents significant deviations from experimental results. We also compare the predictions for surface tension as obtained from simulation results for all the models with

On interfacial properties of tetrahydrofuran: Atomistic and coarse-grained models from molecular dynamics simulation

International Nuclear Information System (INIS)

Garrido, J. M.; Algaba, J.; Blas, F. J.; Míguez, J. M.; Mendiboure, B.; Moreno-Ventas Bravo, A. I.; Piñeiro, M. M.

2016-01-01

We have determined the interfacial properties of tetrahydrofuran (THF) from direct simulation of the vapor-liquid interface. The molecules are modeled using six different molecular models, three of them based on the united-atom approach and the other three based on a coarse-grained (CG) approach. In the first case, THF is modeled using the transferable parameters potential functions approach proposed by Chandrasekhar and Jorgensen [J. Chem. Phys. 77, 5073 (1982)] and a new parametrization of the TraPPE force fields for cyclic alkanes and ethers [S. J. Keasler et al., J. Phys. Chem. B 115, 11234 (2012)]. In both cases, dispersive and coulombic intermolecular interactions are explicitly taken into account. In the second case, THF is modeled as a single sphere, a diatomic molecule, and a ring formed from three Mie monomers according to the SAFT-γ Mie top-down approach [V. Papaioannou et al., J. Chem. Phys. 140, 054107 (2014)]. Simulations were performed in the molecular dynamics canonical ensemble and the vapor-liquid surface tension is evaluated from the normal and tangential components of the pressure tensor along the simulation box. In addition to the surface tension, we have also obtained density profiles, coexistence densities, critical temperature, density, and pressure, and interfacial thickness as functions of temperature, paying special attention to the comparison between the estimations obtained from different models and literature experimental data. The simulation results obtained from the three CG models as described by the SAFT-γ Mie approach are able to predict accurately the vapor-liquid phase envelope of THF, in excellent agreement with estimations obtained from TraPPE model and experimental data in the whole range of coexistence. However, Chandrasekhar and Jorgensen model presents significant deviations from experimental results. We also compare the predictions for surface tension as obtained from simulation results for all the models with

Di-μ-chlorido-bis{[μ-1,8-bis(diisopropylphosphanyl-9,10-dihydro-9,10-ethanoanthracene-κ2P:P′]-μ-chlorido-μ-methylidene-dipalladium(II} tetrahydrofuran pentasolvate

Directory of Open Access Journals (Sweden)

Thomas Schnetz

2010-04-01

Full Text Available The title compound, [Pd4(CH22Cl4(C28H40P22]·5C4H8O, possesses a tetranuclear palladium core with four bridging chlorido ligands and two bridging methylene units, as well as two bridging anthracene-based bis-phosphine ligands. This tetranuclear complex can be considered as being composed of two μ-chlorido-bridged LPd2 units. The structural motif of these LPd2 units shows two doubly bridged palladium centers between the P atoms of the bis-phosphine ligand. One of these bridges is a μ-Cl atom, the other a μ-methylene group. The coordination environment around each palladium center is essentially square planar. We ascribe the oxidation state +II to the palladium centers and do not assume Pd—Pd bonds [shortest distances 2.8110 (5 and 2.8109 (6 Å]. Co-crystallized with the palladium complex we found five non-coordinating tetrahydrofuran solvent molecules, one of which is disordered over two positions in a 0.429 (9:0.571 (8 ratio.

Formation of the reduced form of furaneol® (2,5-dimethyl-4-hydroxy-tetrahydrofuran-3-one) during the Maillard reaction through catalysis of amino acid metal salts.

Science.gov (United States)

Nashalian, Ossanna; Wang, Xi; Yaylayan, Varoujan A

2016-11-01

Under pyrolytic conditions the acidity/basicity of Maillard reaction mixtures can be controlled through the use of hydrochloride or sodium salts of amino acids to generate a diversity of products. When the degradation of glucose was studied under pyrolytic conditions using excess sodium glycinate the reaction was found to generate a major unknown peak having a molecular ion at m/z 130. Subsequent in-depth isotope labelling studies indicated that acetol was an important precursor of this compound under pyrolytic and aqueous heating conditions. The dimerisation and cyclisation of acetol into 2,5-dimethyl-4-hydroxy-tetrahydrofuran-3-one was found to be catalysed by amino acid metal salts. Also, ESI/qTOF/MS studies indicated that the unknown peak has expected molecular formula of C6H10O3. Finally, a peak having the same retention time and mass spectrum was also generated pyrolytically when furaneol® was reduced with NaBH4 confirming the initial hypothesis regarding the unknown peak to be the reduced form of furaneol®. Copyright © 2016 Elsevier Ltd. All rights reserved.

Continuous hydrogenation of ethyl levulinate to γ-valerolactone and 2-methyl tetrahydrofuran over alumina doped Cu/SiO2 catalyst: the potential of commercialization

Science.gov (United States)

Zheng, Junlin; Zhu, Junhua; Xu, Xuan; Wang, Wanmin; Li, Jiwen; Zhao, Yan; Tang, Kangjian; Song, Qi; Qi, Xiaolan; Kong, Dejin; Tang, Yi

2016-01-01

Hydrogenation of levulinic acid (LA) and its esters to produce γ-valerolactone (GVL) and 2-methyl tetrahydrofuran (2-MTHF) is a key step for the utilization of cellulose derived LA. Aiming to develop a commercially feasible base metal catalyst for the production of GVL from LA, with satisfactory activity, selectivity, and stability, Al2O3 doped Cu/SiO2 and Cu/SiO2 catalysts were fabricated by co-precipitation routes in parallel. The diverse physio-chemical properties of these two catalysts were characterized by XRD, TEM, dissociative N2O chemisorptions, and Py-IR methods. The catalytic properties of these two catalysts were systematically assessed in the continuous hydrogenation of ethyl levulinate (EL) in a fixed-bed reactor. The effect of acidic property of the SiO2 substrate on the catalytic properties was investigated. To justify the potential of its commercialization, significant attention was paid on the initial activity, proper operation window, by-products control, selectivity, and stability of the catalyst. The effect of reaction conditions, such as temperature and pressure, on the performance of the catalyst was also thoroughly studied. The development of alumina doped Cu/SiO2 catalyst strengthened the value-chain from cellulose to industrially important chemicals via LA and GVL. PMID:27377401

Excess molar volume, viscosity, and refractive index study for the ternary mixture {2-methyl-2-butanol (1) + tetrahydrofuran (2) + propylamine (3)} at different temperatures. Application of the ERAS-model and Peng-Robinson-Stryjek-Vera equation of state

International Nuclear Information System (INIS)

Fattahi, M.; Iloukhani, H.

2010-01-01

Densities, viscosities, and refractive indices of the ternary mixture consist of {2-methyl-2-butanol (1) + tetrahydrofuran (THF) (2) + propylamine (3)} at a temperature of 298.15 K and related binary mixtures were measured at temperatures of (288.15, 298.15, and 308.15) K at ambient pressure. Data were used to calculate the excess molar volumes and the deviations of the viscosity and refractive index. The Redlich-Kister and the Cibulka equations were used for correlating binary and ternary properties, respectively. The ERAS-model has been applied for describing the binary and ternary excess molar volumes and also Peng-Robinson-Stryjek-Vera (PRSV) equation of state (EOS) has been used to predict the binary and ternary excess molar volumes and viscosities.

Apparent molar volumes and apparent molar heat capacities of aqueous tetrahydrofuran, dimethyl sulfoxide, 1,4-dioxane, and 1,2-dimethoxyethane at temperatures from 278.15 K to 393.15 K and at the pressure 0.35 MPa

International Nuclear Information System (INIS)

Swenson, D.M.; Blodgett, M.B.; Ziemer, S.P.; Woolley, E.M.

2008-01-01

We determined apparent molar volumes V φ at 278.15 ≤ (T/K) ≤ 368.15 and apparent molar heat capacities C p,φ at 278.15 ≤ (T/K) ≤ 393.15 at p = 0.35 MPa for aqueous solutions of tetrahydrofuran at m from (0.016 to 2.5) mol . kg -1 , dimethyl sulfoxide at m from (0.02 to 3.0) mol . kg -1 , 1,4-dioxane at m from (0.015 to 2.0) mol . kg -1 , and 1,2-dimethoxyethane at m from (0.01 to 2.0) mol . kg -1 . Values of V φ were determined from densities measured with a vibrating-tube densimeter, and values of C p,φ were determined with a twin fixed-cell, differential, temperature-scanning calorimeter. Empirical functions of m and T for each compound were fitted to our V φ and C p,φ results

Curcumin/poly(2-methyl-2-oxazoline-b-tetrahydrofuran-b-2-methyl-2-oxazoline) formulation: An improved penetration and biological effect of curcumin in F508del-CFTR cell lines.

Science.gov (United States)

Gonçalves, Cristine; Gomez, Jean-Pierre; Même, William; Rasolonjatovo, Bazoly; Gosset, David; Nedellec, Steven; Hulin, Philippe; Huin, Cécile; Le Gall, Tony; Montier, Tristan; Lehn, Pierre; Pichon, Chantal; Guégan, Philippe; Cheradame, Hervé; Midoux, Patrick

2017-08-01

Neutral amphiphilic triblock ABA copolymers are of great interest to solubilize hydrophobic drugs. We reported that a triblock ABA copolymer consisting of methyl-2-oxazoline (MeOx) and tetrahydrofuran (THF) (MeOx 6 -THF 19 -MeOx 6 ) (TBCP2) can solubilize curcumin (Cur) a very hydrophobic molecule exhibiting multiple therapeutic effects but whose insolubility and low stability in water is a major drawback for clinical applications. Here, we provide evidences by flow cytometry and confocal microscopy that Cur penetration in normal and ΔF508-CFTR human airway epithelial cell lines is facilitated by TBCP2. When used on ΔF508-CFTR cell lines, the Cur/TBCP2 formulation promotes the restoration of the expression of the CFTR protein in the plasma membrane. Furthermore, patch-clamp and MQAE fluorescence experiments show that this effect is associated with a correction of a Cl - selective current at the membrane surface of F508del-CFTR cells. The results show the great potential of the neutral amphiphilic triblock copolymer MeOx 6 -THF 19 -MeOx 6 as carrier for curcumin in a Cystic Fibrosis context. We anticipate that other MeOx n -THF m -MeOx n copolymers could have similar behaviours for other highly insoluble therapeutic drugs or cosmetic active ingredients. Copyright © 2017 Elsevier B.V. All rights reserved.

(Liquid + liquid), (solid + liquid), and (solid + liquid + liquid) equilibria of systems containing cyclic ether (tetrahydrofuran or 1,3-dioxolane), water, and a biological buffer MOPS

International Nuclear Information System (INIS)

Altway, Saidah; Taha, Mohamed; Lee, Ming-Jer

2015-01-01

Graphical abstract: - Highlights: • MOPS buffer induced liquid phase splitting for mixtures of water with THF or 1,3-dioxolane. • Phase boundaries of LLE, SLE, and SLLE were determined experimentally. • Tie-lines at LLE and at SLLE were also measured. • Phase diagrams of MOPS + water + THF or 1,3-dioxolane are prepared. • LLE tie-line data are correlated satisfactorily with the NRTL model. - Abstract: Two liquid phases were formed as the addition of a certain amount of biological buffer 3-(N-morpholino)propane sulfonic acid (MOPS) in the aqueous solutions of tetrahydrofuran (THF) or 1,3-dioxolane. To evaluate the feasibility of recovering the cyclic ethers from their aqueous solutions with the aid of MOPS, we determined experimentally the phase diagrams of the ternary systems of {cyclic ether (THF or 1,3-dioxolane) + water + MOPS} at T = 298.15 K under atmospheric pressure. In this study, the solubility data of MOPS in water and in the mixed solvents of water/cyclic ethers were obtained from the results of a series of density measurements, while the (liquid + liquid) and the (solid + liquid + liquid) phase boundaries were determined by visually inspection. Additionally, the tie-line results for (liquid + liquid) equilibrium (LLE) and for (solid + liquid + liquid) equilibrium (SLLE) were measured using an analytical method. The reliability of the experimental LLE tie-line results data was validated by using the Othmer–Tobias correlation. These LLE tie-line values were correlated well with the NRTL model. The phase diagrams obtained from this study reveal that MOPS is a feasible green auxiliary agent to recover the cyclic ethers from their aqueous solutions, especially for 1,3-dioxolane

Stability conditions and guest distribution of the methane + ethane + propane hydrates or semiclathrates in the presence of tetrahydrofuran or quaternary ammonium salts

International Nuclear Information System (INIS)

Lee, Seungmin; Lee, Youngjun; Park, Sungwon; Kim, Yunju; Cha, Inuk; Seo, Yongwon

2013-01-01

Highlights: • We examined the stability conditions and guest distributions of natural gas hydrates. • THF, TBAB, and TBAF could remarkably stabilize the hydrate dissociation conditions. • Preferential occupation of CH 4 molecules was observed at the stoichiometric concentrations. -- Abstract: In this study, the stability conditions and guest distributions of methane (CH 4 ) + ethane (C 2 H 6 ) + propane (C 3 H 8 ) hydrates or semiclathrates are examined in the presence of tetrahydrofuran (THF) and quaternary ammonium salts such as tetra-n-butylammonium bromide (TBAB) and tetra-n-butylammonium fluoride (TBAF) through thermodynamic and spectroscopic analyses. The three-phase equilibria of hydrate or semiclathrate (H), liquid water (L W ), and vapor (V) for the quinary CH 4 + C 2 H 6 + C 3 H 8 + THF + water, CH 4 + C 2 H 6 + C 3 H 8 + TBAB + water, and CH 4 + C 2 H 6 + C 3 H 8 + TBAF + water mixtures with various concentrations were experimentally measured in order to determine the hydrate or semiclathrate stability conditions. The experimental results demonstrated that all thermodynamic promoters such as THF, TBAB, and TBAF used in this study could remarkably stabilize the hydrate dissociation conditions even though the degree of stabilization was dependent on the type of promoters and on the concentrations of each promoter used. From the 13 C NMR analysis, preferential occupation of CH 4 molecules in the hydrate or semiclathrate lattices was observed at the stoichiometric concentrations of each hydrate or semiclathrate structure. However, at the THF mole fraction lower than 0.056, the large cages of structure II were shared by CH 4 , C 2 H 6 , C 3 H 8 , and THF molecules, whereas the small cages were occupied by only CH 4 molecules. The results given in this study are very useful in understanding the thermodynamic stability, structural characteristics, and guest distribution of the hydrates or semiclathrates with multi-components in the presence of

Densities, speeds of sound and viscosities of binary mixtures of tetrahydrofuran with 1-hexanol, 1-octanol and 1-decanol at T = (298.15 to 313.15) K

International Nuclear Information System (INIS)

Dubey, Gyan Prakash; Kumar, Rajiv

2014-01-01

Highlights: • Thermodynamic study for the binary liquid mixtures has been made. has been made. • Excess molar volumes, deviations of speed of sound and excess molar isentropic compressibilities were determined. • Discussion has been carried out on the basis of types of interactions between the liquid molecules based on derived properties. -- Abstract: Density ρ, and speed of sound u, have been measured for the binary mixtures of tetrahydrofuran (C 4 H 8 O) with 1-hexanol, (C 6 H 14 O), 1-octanol, (C 8 H 18 O) and 1-decanol, (C 10 H 22 O) over the entire composition range at T = (298.15, 303.15, 308.15 and 313.15) K and at atmospheric pressure while viscosity, η was measured at T = (298.15, 303.15, 308.15) K and at atmospheric pressure. The experimental density and speed of sound values were used to calculate the excess molar volumes VmE, deviations in speed of sound u D and excess molar isentropic compressibility K S,m E , while the viscosity data were used to compute excess Gibbs energy of activation of viscous flow, ΔG *E at 298.15, 303.15 and 308.15 K. The values of VmE, u D and K S,m E were fitted to the Redlich–Kister polynomial equation and the viscosity data have been correlated by using the equations of Grunberg–Nissan, Tamura–Kurata, Hind et al., Heric–Brewer (three parameter) and McAllister (four body interactions) and have been used to discuss the presence of significant interactions between cyclic ether and alcohols

Structure and reactivity of lithium amides. /sup 6/Li, /sup 13/C, and /sup 15/N NMR spectroscopic studies and colligative measurements of lithium diphenylamide and lithium diphenylamide-lithium bromide complex solvated by tetrahydrofuran

Energy Technology Data Exchange (ETDEWEB)

DePue, J.S.; Collum, D.B.

1988-08-03

/sup 6/Li, /sup 13/C, and /sup 15/N NMR spectroscopic studies of lithium diphenylamide in THF/hydrocarbon solutions (THF = tetrahydrofuran) detected two different species. /sup 6/Li and /sup 15/N NMR spectroscopic studies of (/sup 6/Li, /sup 15/N)lithium diphenylamide showed the species observed at low THF concentrations to be a cyclic oligomer. Structural analogies provided strong support for a dimer while colligative measurements at 0/degrees/C indicated the dimer to be di- or trisolvated. On the basis of the observed mass action effects, the species appearing at intermediate THF concentrations is assigned as a contact or solvent-separated ion-paired monomer. Lithium diphenylamide forms a 1:1 adduct with lithium bromide at low THF concentrations. A combination of /sup 6/Li-/sup 15/N double labeling studies and colligative measurements supports a trisolvated cyclic mixed dimer structure. Although detailed spectroscopic studies at elevated THF concentrations were precluded by high fluctionality, the similarity of the /sup 13/C chemical shifts of lithium diphenylamide in the presence and absence of lithium bromide provide indirect evidence that the mixed dimer undergoes a THF concentration dependent dissociation to the monomeric amide and free lithium bromide. 24 references, 9 figures, 2 tables.

Racemic methyl 3,10-dioxa-2-azatricyclo[6.2.1.02,6]undecane-4- carboxylate

KAUST Repository

Moosa, Basem

2011-04-29

The structure of the racemic title compound, C10H 15NO4, consists of a tricyclic skeleton comprising a six-membered piperidine ring and five-membered isoxazolidine and tetrahydrofuran rings. The piperidine ring adopts a distorted chair conformation, while the isoxazolidine and tetrahydrofuran rings have envelope conformations.

Racemic methyl 3,10-dioxa-2-azatricyclo[6.2.1.02,6]undecane-4-carboxylate

Directory of Open Access Journals (Sweden)

Basem A. Moosa

2011-05-01

Full Text Available The structure of the racemic title compound, C10H15NO4, consists of a tricyclic skeleton comprising a six-membered piperidine ring and five-membered isoxazolidine and tetrahydrofuran rings. The piperidine ring adopts a distorted chair conformation, while the isoxazolidine and tetrahydrofuran rings have envelope conformations.

Treatments of intrinsic viscosity and glass transition temperature data of poly(2,6-dimethylphenylmethacrylate)

International Nuclear Information System (INIS)

Hamidi, Nasrollah; Massoudi, Ruhullah

2003-01-01

A useful relationship, ln(T g )=ln(T g,∞ )-m[η] -ν , between intrinsic viscosity and glass transition temperature for a series of homologous polymers was obtained by combining the Mark-Houwink-Kuhn-Sakurada (MHKS) relation for intrinsic viscosity and molecular mass, and the Fox-Flory equation for glass transition temperature and number-average molecular mass. This relationship was applied to poly(2,6-dimethylphenylmethacrylate) (PDMPh) in a variety of solvents (ideal to good) such as toluene, tetrahydrofuran/water, tetrahydrofuran, and chlorobenzene systems. The parameter α estimated by this procedure in toluene, tetrahydrofuran/water, tetrahydrofuran, and chlorobenzene systems are 0.50 6 , 0.51 1 , 0.56 7 , and 0.67 3 , respectively which are in agreement with those of Mark-Houwink-Kuhn-Sakurada values by less than 5% differences. The T g,∞ quantity estimated from this equation also is within the standard deviation of that obtained from the Fox-Flory method. The m quantity is increasing as the thermodynamic quality of the solvent improves, therefore, m may be considered as an indicator of coil conformations in a given solvent

Improved Logistics for Chemical and Biologics Decontamination for Deployed Military

Science.gov (United States)

2012-07-01

miscible with ethanolamine (the main solvent of the lanthanide neutralization system) include tetrahydrofuran (THF), ethyl lactate, dimethylsulfoxide ...55 Preliminary Co- Solvent Testing Solvent –Rubber Interaction Observations NMP – 1-Methyl-2-pyrrolidone THF – Tetrahydrofuran DMSO ...salts and/or the incorporation of a variety of components such as co- solvents , emulsifiers, and other additives to improve their neutralization

Multidisciplinary Research for Demining

Science.gov (United States)

2002-11-30

array comprised of 10 MOSFETs and 6 tin oxide sensors. This parallel array was used to predict the fermentation of wood hydrolysates and to estimate...variety of other test analytes (including water, methanol, benzene, toluene, diesel fuel, lighter fluid, vinegar , and tetrahydrofuran) in a laboratory air...backgrounds of potential interferences, including water, methanol, benzene, toluene, diesel fuel, lighter fluid, vinegar , and tetrahydrofuran, even when

Synthesis of 3-acetyl-N-aryl-4-diethylaminoselenet-2(2H)-imines from 4-diethylamino-3-butyn-2-one and aryl isoselenocyanates

OpenAIRE

Atanassov, Plamen K; Linden, Anthony; Heimgartner, Heinz

2004-01-01

The reaction of aryl isoselenocyanates (1a-d) with 4-diethylamino-3-butyn-2-one (6) in refluxing tetrahydrofuran afforded N-arylselenet-2(2H)-imines (7) in moderate yields. The structure of the stable 4-bromophenyl derivative (7b) has been established by X-Ray crystallography. A stepwise cycloaddition via an intermediate zwitterion (A/A¢) is proposed as the reaction mechanism. In boiling tetrahydrofuran, the selenetimines (7) are in equilibrium with ketenimines (B), which were intercepted by ...

Preferential solvation of fluorenone and 4-hydroxyfluorenone in binary solvent mixtures

International Nuclear Information System (INIS)

Jozefowicz, Marek; Heldt, Janina R.

2003-01-01

Preferential solvation of fluorenone and 4-hydroxyfluorenone in binary solvent mixtures has been studied using steady-state spectroscopic measurements. This study concerns the solvent-induced shift of the absorption and fluorescence spectra of both molecules in two solvent mixtures, i.e., cyclohexane-tetrahydrofuran and cyclohexane-ethanol. The first system contains polar solute molecules, fluorenone and 4-hydroxyfluorenone, in a mixture of polar aprotic (tetrahydrofuran) and non-polar (cyclohexane) solvents. In the second solvents mixture, hydrogen bonding with solute molecules (ethanol) may occur. The results of spectroscopic measurements are analysed using theoretical models of Bakshiev, Mazurenko and Suppan which describe preferential solvation phenomena. In the case of cyclohexane-tetrahydrofuran mixtures, the deviation from linearity in the absorption and fluorescence solvatochromic shifts vs. the solution polarity is due to non-specific dipolar solvent-solute interactions. For cyclohexane-ethanol binary mixtures, both non-specific and specific (hydrogen bond and proton-relay tautomerization) interactions contribute to the observed solvatochromism

Determination and correlation thermodynamic models for solid–liquid equilibrium of the Nifedipine in pure and mixture organic solvents

International Nuclear Information System (INIS)

Wu, Gang; Hu, Yonghong; Gu, Pengfei; Yang, Wenge; Wang, Chunxiao; Ding, Zhiwen; Deng, Renlun; Li, Tao; Hong, Housheng

2016-01-01

Highlights: • The solubility increased with increasing temperature. • The data were fitted using the modified Apelblat equation in pure solvents. • The data were fitted using the CNIBS/R-K model in binary solvent mixture. - Abstract: Knowledge of thermodynamic parameters on corresponding solid-liquid equilibrium of nifedipine in different solvents is essential for a preliminary study of pharmaceutical engineering and industrial applications. In this paper, a gravimetric method was used to correct the solid-liquid equilibrium of nifedipine in methanol, ethanol, 1-butanol, acetone, acetonitrile, ethyl acetate and tetrahydrofuran pure solvents as well as in the (tetrahydrofuran + acetonitrile) mixture solvents at temperatures from 278.15 K to 328.15 K under 0.1 MPa. For the temperature range investigation, the solubility of nifedipine in the solvents increased with increasing temperature. The solubility of nifedipine in tetrahydrofuran is superior to other selected pure solvents. The modified Apelblat model, the Buchowski-Ksiazaczak λh model, and the ideal model were adopted to describe and predict the change tendency of solubility. Computational results showed that the modified Apelblat model stood out to be more suitable with the higher accuracy. The solubility values were fitted using a modified Apelblat model, a variant of the combined nearly ideal binary solvent/Redich-Kister (CNIBS/R-K) model and Jouyban-Acree model in (tetrahydrofuran + acetonitrile) binary solvent mixture. Computational results showed that the CNIBS/R-K model had more advantages than other models.

Thermodynamic models for determination of the solubility of omeprazole in pure and mixture organic solvents from T = (278.15 to 333.15) K

International Nuclear Information System (INIS)

Hu, Yonghong; Wu, Gang; Gu, Pengfei; Yang, Wenge; Wang, Chunxiao; Ding, Zhiwen; Cao, Yang

2016-01-01

Highlights: • The solubility increased with increasing temperature. • The data were fitted using the modified Apelblat equation and other models. • The Gibbs energy, enthalpy and entropy were calculated by the van’t Hoff analysis. - Abstract: Data on corresponding (solid + liquid) equilibrium of omeprazole in different solvents are essential for a preliminary study of industrial applications. In this paper, the (solid + liquid) equilibrium of omeprazole in water, methanol, ethanol, 1-butanol, acetonitrile, acetone, ethyl acetate, tetrahydrofuran pure solvents and (tetrahydrofuran + ethyl acetate) mixture solvents were explored within the temperatures from 278.15 K to 333.15 K under atmosphere pressure. For the temperature range investigated, the solubility of omeprazole in the solvents increased with increasing temperature. From (278.15 to 333.15) K, the solubility of omeprazole in tetrahydrofuran is superior to other selected pure solvents. The modified Apelblat model, the Buchowski–Ksiazaczak λh model, and the ideal model were adopted to describe and predict the change tendency of solubility. Computational results showed that the modified Apelblat model has advantages than the other two models. Numerical values of the solubility were fitted using a modified Apelblat equation, a variant of the combined nearly ideal binary solvent/Redich–Kister (CNIBS/R–K) model and Jouyban–Acree model in (tetrahydrofuran + ethyl acetate) binary solvent mixture. Computational results showed that the CNIBS/R–K model is superior to the other equations. In addition, the calculated thermodynamic parameters indicate that in each solvent studied the dissolution of omeprazole is endothermic, non-spontaneous and is an entropy-driven process.

Low energy electron-initiated ion-molecule reactions of ribose analogues

International Nuclear Information System (INIS)

Mozejko, P.

2003-01-01

Recent experiments in which plasmid DNA samples were bombarded with low energy ( 2 O, DNA bases, and sugar-phosphate backbone analogues. To this end, the cyclic molecule tetrahydrofuran, and its derivatives, provide useful models for the sugar-like molecules contained in the backbone of DNA. In addition to LEE induced dissociation by processes such as dissociative electron attachment (DEA), molecules may be damaged by ions and neutral species of non-thermal energies created by LEE in the surrounding environment. In this contribution, we investigate with electron stimulated desorption techniques, LEE damage to films of desoxy-ribose analogues in the presence of various molecular coadsorbates, that simulate changes in local molecular environment. In one type of experiments tetrahydrofuran is deposited onto multilayer O2. A desorbed signal of OH - indicates ion-molecule reactions of the type O - + C 4 H 8 O -> OH - + C 4 H 7 O, where the O - was formed initially by DEA to O 2 . Further electron stimulated desorption measurements for tetrahydrofuran and derivatives adsorbed on H 2 O, Kr, N 2 O and CH 3 OH will be presented and discussed

Crystal structures of hibiscus acid and hibiscus acid dimethyl ester isolated from Hibiscus sabdariffa (Malvaceae)

OpenAIRE

Zheoat, Ahmed M.; Gray, Alexander I.; Igoli, John O.; Kennedy, Alan R.; Ferro, Valerie A.

2017-01-01

The biologically active title compounds have been isolated from Hibiscus sabdariffa plants, hibiscus acid as a dimethyl sulfoxide monosolvate [systematic name: (2S,3R)-3-hy?droxy-5-oxo-2,3,4,5-tetra?hydro?furan-2,3-di?carb?oxy?lic acid dimethyl sulfoxide monosolvate], C6H6O7?C2H6OS, (I), and hibiscus acid dimethyl ester [systematic name: dimethyl (2S,3R)-3-hy?droxy-5-oxo-2,3,4,5-tetra?hydro?furan-2,3-di?carboxyl?ate], C8H10O7, (II). Compound (I) forms a layered structure with alternating laye...

Evaluation of miscibility of poly(epichlorohydrin-co-ethylene oxide) and poly(methylmethacrylate) blends

International Nuclear Information System (INIS)

Turchete, Renato; Felisberti, Maria Isabel

1999-01-01

The miscibility of blends of poly(methylmethacrylate), (PMMA) and poly(epichlorohydrin-co-ethylene oxide), (ECO) were investigated by differential scanning calorimetry. The ECO was fractionated using two different systems: a solvent-non solvent system and by cooling the solution in tetrahydrofuran in the temperature range from 20 to 0 deg C. The fractions with different composition and molecular weight were used to prepare the blends by casting from solution in tetrahydrofuran. The blends exhibit two glass transitions shifted in relation to the glass transitions of the pure polymers, indicating a partial miscibility. Blends containing copolymer richer in epichlorohydrin segments were more miscible than blends of non-fractionated ECO. (author)

Process for the reduction of nitrogen oxides in an effluent

Energy Technology Data Exchange (ETDEWEB)

Epperly, W.R.; Sullivan, J.C.; Sprague, B.N.

1989-07-04

This patent describes a process for the reduction of the concentration of nitrogen oxides in the effluent from the combustion of a carbonaceous fuel. The process comprises introducing a treatment agent which comprises a composition selected from the group consisting of NH/sub 4/-lignosulfonate, calcium lignosulfonate, 2-furoic acid, 1,3 dioxolane, tetrahydrofuran, furfurylamine, furfurylalcohol, gluconic acid, citric acid, n-butyl acetate, 1,3 butylene glycol, methylal, tetrahydrofuryl alcohol, furan, fish oil, coumalic acid, furfuryl acetate, tetrahydrofuran 2,3,4,5-tetracarboxylic acid, tetrahydrofurylamine, furylacrylic acid, tetrahydropyran, 2,5-furandimethanol, mannitol, hexamethylenediamine, barbituric acid, acetic anhydride, oxalic acid, mucic acid and d-galactose.

Biological activities of lignoids from Amazon Myristicaceae species: Virota michelii, V. mollissima, V. pavonis and Iryanthera juruensis

International Nuclear Information System (INIS)

Morais, Sabrina K.R.; Yoshida, Massayoshi; Teixeira, Ana F.; Torres, Zelina E. dos S.; Numomura, Sergio M.; Yamashiro-Kanashiro, Edite H.; Lindoso, Jose Angelo I.

2009-01-01

This work revisits the fruits of Iryanthera juruensis and Virola pavonis and the leaves from V. michelii, as well as describing a study of the fruits of V. mollissima. In I. juruensis aryltetraline neolignan (1) and tetrahydrofuran neolignan (2), were found while from V. pavonis neolignans of benzofuran type (6-9), the tetrahydrofuran type (2, 11-13, 17) and the biphenyl type (10), in addition to diastereoisomers of the 8.O.4'-oxyneolignan type (14 and 15) and others were isolated. The V. mollissima accumulates the aryltetralone neolignan 4 and its seco derivative (5). The lignoids 1 and 2 obtained from I. juruensis arils possess antileishmanial activity against the promastigote form of Leishmania amazonensis. (author)

Biological activities of lignoids from Amazon Myristicaceae species: Virota michelii, V. mollissima, V. pavonis and Iryanthera juruensis

Energy Technology Data Exchange (ETDEWEB)

Morais, Sabrina K.R.; Yoshida, Massayoshi [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Quimica; Centro de Biotecnologia da Amazonia, Manaus, AM (Brazil)], e-mail: myoshida@iq.usp.br; Teixeira, Ana F. [Universidade do Estado do Amazonas, Manaus, AM (Brazil). Escola Normal Superior; Torres, Zelina E. dos S. [Universidade do Estado do Amazonas, Manaus, AM (Brazil). Escola Superior de Ciencias da Saude; Numomura, Sergio M. [Instituto Nacional de Pesquisas da Amazonia (INPA), Manaus, AM (Brazil). Coordenacao de Pesquisa de Produtos Naturais; Yamashiro-Kanashiro, Edite H.; Lindoso, Jose Angelo I. [Universidade de Sao Paulo, SP (Brazil). Hospital das Clinicas. Lab. de Epidemiologia e Imunobiologia

2009-07-01

This work revisits the fruits of Iryanthera juruensis and Virola pavonis and the leaves from V. michelii, as well as describing a study of the fruits of V. mollissima. In I. juruensis aryltetraline neolignan (1) and tetrahydrofuran neolignan (2), were found while from V. pavonis neolignans of benzofuran type (6-9), the tetrahydrofuran type (2, 11-13, 17) and the biphenyl type (10), in addition to diastereoisomers of the 8.O.4'-oxyneolignan type (14 and 15) and others were isolated. The V. mollissima accumulates the aryltetralone neolignan 4 and its seco derivative (5). The lignoids 1 and 2 obtained from I. juruensis arils possess antileishmanial activity against the promastigote form of Leishmania amazonensis. (author)

Solvent and polymer concentration effects on the surface morphology evolution of immiscible polystyrene/poly(methyl methacrylate) blends

International Nuclear Information System (INIS)

Cui Liang; Ding Yan; Li Xue; Wang Zhe; Han Yanchun

2006-01-01

The effects of solvent nature on the surface topographies of polystyrene (PS)/poly(methyl methacrylate) (PMMA) blend films spin-coated onto the silicon wafer were investigated. Four different solvents, such as ethylbenzene, toluene, tetrahydrofuran and dichloromethane, were chosen. They are better solvents for PS than that for PMMA. When dichloromethane, tetrahydrofuran and toluene were used, PMMA-rich phase domains protruded from the background of PS. When ethylbenzene was used, PS-rich phase domains elevated on the average height of PMMA-rich phase domains. In addition, continuous pits, networks and isolated droplets consisted of PS formed on the blend film surfaces with the decrease of polymer concentrations. The mechanism of the surface morphology evolution was discussed in detail

Influência de diferentes solventes utilizados na deposição de filme de poli(9-vinilcarbazol em dispositivos OLEDs

Directory of Open Access Journals (Sweden)

Emerson Roberto Santos

2014-01-01

Full Text Available This work studies the influence of the film deposition process on light emission performance and on threshold voltage of OLEDs, with architecture glass/ITO/PEDOT:PSS/PVK/Alq3/Al. The commercial PVK was dissolved in different solvents such as: chloroform, tetrahydrofuran, 1,2,4-trichlorobenzene and trimethylpentane. OLEDs were characterized by current-voltage and revealed a significant influence of the solvents, although all devices emitted green electroluminescence. A difference in threshold voltage up to 10 V was observed among OLEDs prepared from different solvents. The 1,2,4-trichlorobenzene showed best performance, presenting lowest treshold voltage (≈ 6 V, followed by tetrahydrofuran (≈ 8 V, trimethylpentane (≈ 14 V and chloroform (≈ 16 V.

Facilitated preparation of bioconjugatable zwitterionic quantum dots using dual-lipid encapsulation.

Science.gov (United States)

Shrake, Robert; Demillo, Violeta G; Ahmadiantehrani, Mojtaba; Zhu, Xiaoshan; Publicover, Nelson G; Hunter, Kenneth W

2015-01-01

Zwitterionic quantum dots prepared through incorporated zwitterionic ligands on quantum dot surfaces, are being paid significant attention in biomedical applications because of their excellent colloidal stability across a wide pH and ionic strength range, antifouling surface, good biocompatibility, etc. In this work, we report a dual-lipid encapsulation approach to prepare bioconjugatable zwitterionic quantum dots using amidosulfobetaine-16 lipids, dipalmitoyl-sn-glycero-3-phosphoethanolamine lipids with functional head groups, and CuInS2/ZnS quantum dots in a tetrahydrofuran/methanol/water solvent system with sonication. Amidosulfobetaine-16 is a zwitterionic lipid and dipalmitoyl-sn-glycero-3-phosphoethanolamine, with its functional head, provides bioconjugation capability. Under sonication, tetrahydrofuran/methanol containing amidosulfobetaine-16, dipalmitoyl-sn-glycero-3-phosphoethanolamine, and hydrophobic quantum dots are dispersed in water to form droplets. Highly water-soluble tetrahydrofuran/methanol in droplets is further displaced by water, which induces the lipid self-assembling on hydrophobic surface of quantum dots and thus forms water soluble zwitterionic quantum dots. The prepared zwitterionic quantum dots maintain colloidal stability in aqueous solutions with high salinity and over a wide pH range. They are also able to be conjugated with biomolecules for bioassay with minimal nonspecific binding. Copyright © 2014 Elsevier Inc. All rights reserved.

Critical assessment of three high performance liquid chromatography analytical methods for food carotenoid quantification.

Science.gov (United States)

Dias, M Graça; Oliveira, Luísa; Camões, M Filomena G F C; Nunes, Baltazar; Versloot, Pieter; Hulshof, Paul J M

2010-05-21

Three sets of extraction/saponification/HPLC conditions for food carotenoid quantification were technically and economically compared. Samples were analysed for carotenoids alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein, lycopene, and zeaxanthin. All methods demonstrated good performance in the analysis of a composite food standard reference material for the analytes they are applicable to. Methods using two serial connected C(18) columns and a mobile phase based on acetonitrile, achieved a better carotenoid separation than the method using a mobile phase based on methanol and one C(18)-column. Carotenoids from leafy green vegetable matrices appeared to be better extracted with a mixture of methanol and tetrahydrofuran than with tetrahydrofuran alone. Costs of carotenoid determination in foods were lower for the method with mobile phase based on methanol. However for some food matrices and in the case of E-Z isomer separations, this was not technically satisfactory. Food extraction with methanol and tetrahydrofuran with direct evaporation of these solvents, and saponification (when needed) using pyrogallol as antioxidant, combined with a HPLC system using a slight gradient mobile phase based on acetonitrile and a stationary phase composed by two serial connected C(18) columns was the most technically and economically favourable method. 2010. Published by Elsevier B.V.

Preparation of carbon quantum dots with a high quantum yield and the application in labeling bovine serum albumin

Energy Technology Data Exchange (ETDEWEB)

Liu, Pengpeng; Zhang, Changchang; Liu, Xiang, E-mail: liuxiang@ahut.edu.cn; Cui, Ping, E-mail: cokecp@sohu.com

2016-04-15

Graphical abstract: - Highlights: • Cheap carbon quantum dots (CQDs) with a high quantum yield were prepared. • The preparation process and surface functionalization on CQDs are rather facile. • Such functionalized CQDs can be attached to BSA covalently. • This predicts that some biomolecules can be labeled by the fluorescent CQDs. - Abstract: An economic and green approach of manufacturing carbon quantum dots (CQDs) with a high quantum yield (denoted with HQY-CQDs) and the application in labeling bovine serum albumin (BSA) were described in detail in this work. Firstly, the cheap resources of citric acid and glycine were pyrolysed in drying oven for preparing the CQDs. Then the product was immersed in tetrahydrofuran for 8 h. HQY-CQDs were obtained by removing tetrahydrofuran from the supernate and were evaluated that they possessed a much higher quantum yield compared with that without dealing with tetrahydrofuran and a wonderful photo-bleaching resistance. Such HQY-CQDs could be functionalized by N-hydroxysuccinimide and successively combined with BSA covalently. Thus fluorescent labeling on BSA was realized. The HQY-CQDs were demonstrated with transmission electron microscopy and the chemical modification with N-hydroxysuccinimide was proved by infrared and X-ray photoelectron spectra. Labeling BSA with the HQY-CQDs was confirmed by gel electrophoresis and fluorescence imaging.

Determination of cholesterol and four phytosterols in foods without derivatization by gas chromatography-tandem mass spectrometry

Directory of Open Access Journals (Sweden)

Yan-Zong Chen

2015-12-01

Full Text Available In this study, a method for determination of cholesterol and four phytosterols by gas chromatography coupled with electron impact ionization mode–tandem mass spectrometry without derivatization in general food was developed. The sample was saponified with 7.5% KOH in methanol. After heating on hot plate and reflux for 60 minutes, the saponified portion was extracted with n-hexane/petroleum ether (50:50, v/v. The extracts were evaporated with rotary evaporator and then redissolved with tetrahydrofuran. The tetrahydrofuran layer was transferred into an injection vial and analyzed by gas chromatography on a 30 m VF-5 column. Limit of quantification was 2 mg/kg. Recoveries of cholesterol and four phytosterols from general food were between 91% and 100%.

Organoamido- and aryloxo-lanthanoids. Pt. IV

International Nuclear Information System (INIS)

Deacon, G.B.; Feng, T.; Nickel, S.; Ogden, M.I.

1992-01-01

This study illustrates the capacity of bulky aryl oxide ligands to stabilize low-coordination numbers in lanthanoid complexes, the isolation of the first low-coordinate hydroxo-bridged complex being of particular interest. (Tetrahydrofuran)tis(2,4,6-tri-t-butylphenolato)ytterbium(III) was isolated following oxidation of the aryloxoytterbium(II) complex Yb(Otbp)2(thf)3 with thallium (I) 2,4,6-tri-t-butylphenolate in tetrahydrofuran. A further synthesis was achieved by redox transmetallation between ytterbium metal and thallium(I) aryl oxide in tetrahydrofuran. The X-ray characterization of Yb(Otbp) 3 (thf)(thp=2,4,6-Bu t -3 C 6h2 ) is also presented. An interesting feature of the bond angles of (2).(thf) n is the marked difference between the O(4)-Yb-O(n) and the corresponding O(4')-Yb-O(n) (n=1-3) values. This illustrates the irregularity of the five coordination. Nevertheless, there is similarity between the sums of the O(4)-Yb-O(n) and O(4')-Yb-O(n) angles (333/336 deg). The Yb-O(H)-Yb and HO-Yb-OH angles of (2).(thf) n are larger and smaller, respectively, than those of the organolanthanoid hydroxides. This reflects the weaker bridging (longer bond lengths) of the present complex. 32 refs., 4 tabs., 2 figs

Thermal stability and structural characteristics of PTHF–Mmt organophile nanocomposite

Directory of Open Access Journals (Sweden)

Youcef Hattab

2015-05-01

The objective of this study is to use organophilized montmorillonites in the presence of monomer tetrahydrofuran to obtain polytétrahydrofuran montmorillonites (PTHF–Mmt of composites by polymerization in situ. The organophilisation of the Mmt is formed by active cationic surface. The obtained results show an increase in the distance inside the reticular in the diffractograms of X-rays (DRX and the appearance of absorption bands of the characteristics of polytétrahydrofuran on the spectra of infrared spectroscopy (IR, which indicate pre-polymerization of tetrahydrofuran in the galleries of clay and, therefore, the obtaining of a nanocomposite. We have also studied the thermal stability of the samples by differential analysis calorimetric (DSC analysis, and we can conclude that the nanocomposites are stabilized thermally by the presence of clay in the matrix.

Crystal structures of a manganese(I and a rhenium(I complex of a bipyridine ligand with a non-coordinating benzoic acid moiety

Directory of Open Access Journals (Sweden)

Sheri Lense

2018-05-01

Full Text Available The structures of two facially coordinated Group VII metal complexes are reported, namely: fac-bromido[2-(2,2′-bipyridin-6-ylbenzoic acid-κ2N,N′]tricarbonylmanganese(I tetrahydrofuran monosolvate, [MnBr(C17H12N2O2(CO3]·C4H8O, I, and fac-[2-(2,2′-bipyridin-6-ylbenzoic acid-κ2N,N′]tricarbonylchloridorhenium(I tetrahydrofuran monosolvate, [ReCl(C17H12N2O2(CO3]·C4H8O, II. In both complexes, the metal ion is coordinated by three carbonyl ligands, a halide ion, and a 2-(2,2′-bipyridin-6-ylbenzoic acid ligand, in a distorted octahedral geometry. In manganese complex I, the tetrahydrofuran (THF solvent molecule could not be refined due to disorder. The benzoic acid fragment is also disordered over two positions, such that the carboxylic acid group is either positioned near to the bromide ligand or to the axial carbonyl ligand. In the crystal of I, the complex molecules are linked by a pair of C—H...Br hydrogen bonds, forming inversion dimers that stack up the a-axis direction. In the rhenium complex II, there is hydrogen bonding between the benzoic acid moiety and a disordered co-crystallized THF molecule. In the crystal, the molecules are linked by C—H...Cl hydrogen bonds, forming layers parallel to (100 separated by layers of THF solvent molecules.

A study on the hydrotreating of coal hydro liquefaction residue and its kinetics

Energy Technology Data Exchange (ETDEWEB)

Huang, J.; Lu, X.; Zhang, D.; Gao, J. [Department of Chemical Engineering for Energy Resources, East China University of Science and Technology, Shanghai (China)

2010-09-15

Hydro-conversion of coal hydro liquefaction residue obtained from a 6 t/day pilot plant of Shenhua Group in Shanghai was carried out under the hydrotreating condition. The coal hydro liquefaction residue and its product were extracted in sequence with n-hexane, toluene and tetrahydrofuran in a Soxhlet apparatus. The n-hexane soluble fractions increased with the increase of reaction temperature and time. Its amount increased from 14.14% to a maximum of 40.86% under the conditions of 470 {sup o}C and 30 min, which meant that moderate extension of coal residence time in the coal hydro liquefaction reactor is beneficial to the increase of oil yield. A 4-lumped kinetic model of coal hydro liquefaction residue hydro-conversion was performed using solubility-based lumped fractions. In the model, the tetrahydrofuran insoluble fractions were classified into two parts: easily reactive part and unreactive part. The kinetic parameters were estimated by a fourth-order Runge-Kutta method and a nonlinear least squares method, and the apparent activation energies were calculated according to the Arrhenius Equation. A large quantity of total catalyst consisting of remained liquefaction catalyst, part of the mineral from raw coal and additive Fe-based catalyst could considerably reduce the apparent activation energy of hydro-conversion for the toluene insoluble/tetrahydrofuran insoluble fractions to 36.79 kJ-mol{sup -1}. The calculated values of the model coincided well with the experimental values. (authors)

A Study on the Hydrotreating of Coal Hydroliquefaction Residue and its Kinetics

Directory of Open Access Journals (Sweden)

Jinsheng Gao

2010-09-01

Full Text Available Hydro-conversion of coal hydroliquefaction residue obtained from a 6t/day pilot plant of Shenhua Group in Shanghai was carried out under the hydrotreating condition. The coal hydroliquefaction residue and its product were extracted in sequence with n-hexane, toluene and tetrahydrofuran in a Soxhlet apparatus. The n-hexane soluble fractions increased with the increase of reaction temperature and time. Its amount increased from 14.14% to a maximum of 40.86% under the conditions of 470 °C and 30 min, which meant that moderate extension of coal residence time in the coal hydroliquefaction reactor is beneficial to the increase of oil yield. A 4-lumped kinetic model of coal hydroliquefaction residue hydro-conversion was performed using solubility-based lumped fractions. In the model, the tetrahydrofuran insoluble fractions were classified into two parts: easily reactive part and unreactive part. The kinetic parameters were estimated by a fourth-order Runge-Kutta method and a nonlinear least squares method, and the apparent activation energies were calculated according to the Arrhenius Equation. A large quantity of total catalyst consisting of remained liquefaction catalyst, part of the mineral from raw coal and additive Fe-based catalyst could considerably reduce the apparent activation energy of hydro-conversion for the toluene insoluble/tetrahydrofuran insoluble fractions to 36.79 kJ•mol-1. The calculated values of the model coincided well with the experimental values.

Characterization of asphaltenes by nonaqueous capillary electrophoresis

NARCIS (Netherlands)

Kok, W.T.; Tüdös, A.J.; Grutters, M.; Shepherd, A.G.

2011-01-01

Nonaqueous capillary electrophoresis was used for the separation and characterization of asphaltene samples from different sources. For the separation medium (background electrolyte), mixtures of tetrahydrofuran and a high-permittivity organic solvent could be used. The best results were obtained

Racemic methyl 3,10-dioxa-2-azatricyclo[6.2.1.02,6]undecane-4- carboxylate

KAUST Repository

Moosa, Basem; Fazal, Atif; Ali, Shaikh A.; Fettouhi, Mohammed

2011-01-01

The structure of the racemic title compound, C10H 15NO4, consists of a tricyclic skeleton comprising a six-membered piperidine ring and five-membered isoxazolidine and tetrahydrofuran rings. The piperidine ring adopts a distorted chair conformation

Crystal structures and spectroscopic properties of 2¿3 phospha-1,3-dionates and 1,3-dionates of calcium ¿ comparative studies on the 1,3-diphenyl- and 1,3-Di(tert-butyl) derivatives¿

NARCIS (Netherlands)

Becker, Gerd; Niemeyer, Mark; Mundt, Otto; Schwarz, Wolfgang; Westerhausen, Matthias; Ossberger, Manfred W.; Mayer, Peter; Nöth, Heinrich; Zhong, Zhiyuan; Dijkstra, Pieter J.; Feijen, Jan

2004-01-01

Der Wasserstoff-Metall-Austausch zwischen Dibenzoylphosphan und Calciumcarbid in Tetrahydrofuran (THF) ergibt nach Zusatz des Liganden 1, 3, 5-Trimethyl-1, 3, 5-triazinan (TMTA) den als Kokristallisat mit Benzol isolierten zweikernigen Komplex Bis[(tmta-N, N, N)calcium-bis(dibenzoylphosphanid)

Encapsulated PDMS microspheres with reactive handles

DEFF Research Database (Denmark)

Gonzalez, Lidia; Ma, Baoguang; Li, Li

2014-01-01

, cured PDMS microspheres are coated with poly(methyl methacrylate) using a chemical process (solvent evaporation technique). Three solvents are used in three different experiments: dichloromethane, tetrahydrofuran, and acetone. The composition and morphology of the cured PDMS microspheres and PMMA coated...

Kinetics of hydrolysis of 4-methoxyphenyl-2,2-dichloroethanoate in binary water-cosolvent mixtures; the role of solvent activity and solute-solute interactions

NARCIS (Netherlands)

Rispens, T; Cabaleiro-Lago, C; Engberts, JBFN

2005-01-01

Rate constants are reported for the pH-independent hydrolysis of 4-methoxyphenyl-2,2-dichloroethanoate in aqueous solution as a function of the concentration of added cyanomethane ( acetonitrile), polyethylene glycol ( PEG 400) and tetrahydrofuran ( THF). The concentration of water was varied

Kinetics of hydrolysis of 4-methoxyphenyl-2,2-dichloroethanoate in binary water-cosolvent mixtures; the role of solvent activity and solute-solute interactions

NARCIS (Netherlands)

Rispens, Theo; Cabaleiro-Lago, Celia; Engberts, Jan B. F. N.

2005-01-01

Rate constants are reported for the pH-independent hydrolysis of 4-methoxyphenyl-2,2-dichloroethanoate in aqueous solution as a function of the concentration of added cyanomethane (acetonitrile), polyethylene glycol (PEG 400) and tetrahydrofuran (THF). The concentration of water was varied between

Zhou et al., Afr J Tradit Complement Altern Med. (2011) 8(4):405 ‐411

African Journals Online (AJOL)

AJTCAM

from six different habitats in China: Zhejiang Province, Anhui Province, Jiangxi Province, Chongqing City, Hunan Province and Hebei Province. Chemicals and reagents. Analytical grade-methanol was purchased from Sigma Aldrich, UK. HPLC-grade water, acetonitrile and tetrahydrofuran (THF) were purchased from Fisher ...

Methyl (9aR*,10S*,11R*,13aS*,13bS*-9-oxo-6,7,9,9a,10,11-hexahydro-5H,13bH-11,13a-epoxypyrrolo[2′,1′:3,4][1,4]diazepino[2,1-a]isoindole-10-carboxylate

Directory of Open Access Journals (Sweden)

Flavien A. A. Toze

2011-11-01

Full Text Available The title compound, C17H18N2O4, is the methyl ester of the adduct of intramolecular Diels–Alder reaction between maleic anhydride and 1-(2-furyl-2,3,4,5-tetrahydro-1H-pyrrolo[1,2-a][1,4]diazepine. The molecule comprises a fused pentacyclic system containing four five-membered rings (viz. pyrrole, 2-pyrrolidinone, tetrahydrofuran and dihydrofuran and one seven-membered ring (1,4-diazepane. The pyrrole ring is approximately planar (r.m.s. deviation = 0.003 Å while the 2-pyrrolidinone, tetrahydrofuran and dihydrofuran five-membered rings have the usual envelope conformations. The central seven-membered diazepane ring adopts a boat conformation. In the crystal, molecules are bound by weak intermolecular C—H...O hydrogen-bonding interactions into zigzag chains propagating in [010]. In the crystal packing, the chains are stacked along the a axis.

A thermodynamic study of complexation process between N, N'-dipyridoxylidene(1,4-butanediamine) and Cd2+ in some binary mixed solvents using conductometry

Science.gov (United States)

Ebrahimpoor, Sonia; Khoshnood, Razieh Sanavi; Beyramabadi, S. Ali

2016-12-01

Complexation of the Cd2+ ion with N, N'-dipyridoxylidene(1,4-butanediamine) Schiff base was studied in pure solvents including acetonitrile (AN), ethanol (EtOH), methanol (MeOH), tetrahydrofuran (THF), dimethylformamide (DMF), water (H2O), and various binary solvent mixtures of acetonitrile-ethanol (AN-EtOH), acetonitrile-methanol (AN-MeOH), acetonitrile-tetrahydrofuran (AN-THF), acetonitrile-dimethylformamide (AN-DMF), and acetonitrile-water (AN-H2O) systems at different temperatures using the conductometric method. The conductance data show that the stoichiometry of complex is 1: 1 [ML] in all solvent systems. A non-linear behavior was observed for changes of log K f of [Cd( N, N'-dipyridoxylidene(1,4-butanediamine)] complex versus the composition of the binary mixed solvents, which was explained in terms of solvent-solvent interactions. The results show that the thermodynamics of complexation reaction is affected by the nature and composition of the mixed solvents.

Solution small-angle x-ray scattering as a screening and predictive tool in the fabrication of asymmetric block copolymer membranes

KAUST Repository

Dorin, Rachel Mika; Marques, Debora S.; Sai, Hiroaki; Vainio, Ulla; Phillip, William A.; Peinemann, Klaus; Nunes, Suzana Pereira; Wiesner, Ulrich B.

2012-01-01

Small-angle X-ray scattering (SAXS) analysis of the diblock copolymer poly(styrene-b-(4-vinyl)pyridine) in a ternary solvent system of 1,4-dioxane, tetrahydrofuran, and N,N-dimethylformamide, and the triblock terpolymer poly(isoprene-b-styrene-b-(4-vinyl)-pyridine) in a binary solvent system of 1,4-dioxane and tetrahydrofuran, reveals a concentration-dependent onset of ordered structure formation. Asymmetric membranes fabricated from casting solutions with polymer concentrations at or slightly below this ordering concentration possess selective layers with the desired nanostructure. In addition to rapidly screening possible polymer solution concentrations, solution SAXS analysis also predicts hexagonal and square pore lattices of the final membrane surface structure. These results suggest solution SAXS as a powerful tool for screening casting solution concentrations and predicting surface structure in the fabrication of asymmetric ultrafiltration membranes from self-assembled block copolymers. (Figure presented) © 2012 American Chemical Society.

Synthesis and studies of some organometallic compounds of uranium IV

International Nuclear Information System (INIS)

Marquet-Ellis, Hubert; Folcher, Gerard.

1975-06-01

The organometallic compounds of uranium IV have been well known for a long-time but some difficulties in the synthese subsist. The procedures and the apparatus allowing to obtain these compounds with good yields are described. The cyclopenta dienyl compounds U(C 5 H 5 ) 3 Cl, U(C 5 H 5 ) 4 are prepared by reaction of UCl 4 with Na(C 5 H 5 ) in tetrahydrofurane. The cyclooctatetraene compound U(C 8 H 8 ) 2 ''Uranocene'' is obtained by reaction of K 2 (C 8 H 8 ) on UCl 4 in tetrahydrofurane. The NMR spectrum of the solution during the reaction shows the appearance of the product. These compounds have been identified by chemical analysis and X rays. The visible spectra of U(C 5 H 5 ) 2 Cl and U(C 8 H 8 ) 2 in gaseous phase have been obtained [fr

Solution small-angle x-ray scattering as a screening and predictive tool in the fabrication of asymmetric block copolymer membranes

KAUST Repository

Dorin, Rachel Mika

2012-05-15

Small-angle X-ray scattering (SAXS) analysis of the diblock copolymer poly(styrene-b-(4-vinyl)pyridine) in a ternary solvent system of 1,4-dioxane, tetrahydrofuran, and N,N-dimethylformamide, and the triblock terpolymer poly(isoprene-b-styrene-b-(4-vinyl)-pyridine) in a binary solvent system of 1,4-dioxane and tetrahydrofuran, reveals a concentration-dependent onset of ordered structure formation. Asymmetric membranes fabricated from casting solutions with polymer concentrations at or slightly below this ordering concentration possess selective layers with the desired nanostructure. In addition to rapidly screening possible polymer solution concentrations, solution SAXS analysis also predicts hexagonal and square pore lattices of the final membrane surface structure. These results suggest solution SAXS as a powerful tool for screening casting solution concentrations and predicting surface structure in the fabrication of asymmetric ultrafiltration membranes from self-assembled block copolymers. (Figure presented) © 2012 American Chemical Society.

Crystal structures of hibiscus acid and hibiscus acid dimethyl ester isolated from Hibiscus sabdariffa (Malvaceae).

Science.gov (United States)

Zheoat, Ahmed M; Gray, Alexander I; Igoli, John O; Kennedy, Alan R; Ferro, Valerie A

2017-09-01

The biologically active title compounds have been isolated from Hibiscus sabdariffa plants, hibiscus acid as a dimethyl sulfoxide monosolvate [systematic name: (2 S ,3 R )-3-hy-droxy-5-oxo-2,3,4,5-tetra-hydro-furan-2,3-di-carb-oxy-lic acid dimethyl sulfoxide monosolvate], C 6 H 6 O 7 ·C 2 H 6 OS, (I), and hibiscus acid dimethyl ester [systematic name: dimethyl (2 S ,3 R )-3-hy-droxy-5-oxo-2,3,4,5-tetra-hydro-furan-2,3-di-carboxyl-ate], C 8 H 10 O 7 , (II). Compound (I) forms a layered structure with alternating layers of lactone and solvent mol-ecules, that include a two-dimensional hydrogen-bonding construct. Compound (II) has two crystallographically independent and conformationally similar mol-ecules per asymmetric unit and forms a one-dimensional hydrogen-bonding construct. The known absolute configuration for both compounds has been confirmed.

A New Tetrahydrofuran Lignan Diglycoside from Viola tianshanica Maxim

Directory of Open Access Journals (Sweden)

Yan Qin

2013-11-01

Full Text Available A new lignan glycoside, tianshanoside A (1, together with a known phenylpropanoid glycoside, syringin (2 and two known lignan glycosides, picraquassioside C (3, and aketrilignoside B (4, were isolated from the whole plant of Viola tianshanica Maxim. The structure of the new compound was elucidated by extensive NMR (1H, 13C, COSY, HSQC, HMBC and ROESY and high resolution mass spectrometry analysis. The three lignans 1, 3, and 4 did not exhibit significant cytotoxicity against human gastric cancer Ags cells or HepG2 liver cancer cells. This is the first report of the isolation of a lignan skeleton from the genus Viola L.

Dielectric relaxation of amides and tetrahydrofuran polar mixture in ...

Indian Academy of Sciences (India)

2016-12-06

Dec 6, 2016 ... in C6H6 from conductivity measurement under 9.90 GHz electric field. S SAHOO1 and S K SIT2∗. 1Department of Electronics & Instrumentation Engineering, National Institute of Technology,. Silchar 788 010, India ... versatile industrial solvent for PVC and in varnishes. ... The thermodynamic energy para-.

DFT-based inhibitor and promoter selection criteria for pentagonal ...

Indian Academy of Sciences (India)

Methane hydrate formation inhibition by methanol and ethylene glycol as well as methane hydrate stabilization by cyclopentane and tetrahydrofuran are critically analysed based on the interaction energy, free energy change, dipole moment and infrared frequency calculation. Calculation of free energy change for formation ...

Rh-Catalyzed annulations of N-methoxybenzamides with ketenimines: synthesis of 3-aminoisoindolinones and 3-diarylmethyleneisoindolinones with strong aggregation induced emission properties.

Science.gov (United States)

Zhou, Xiaorong; Peng, Zhixing; Zhao, Hongyang; Zhang, Zhiyin; Lu, Ping; Wang, Yanguang

2016-08-23

Rhodium-catalyzed C-H activation/annulation reactions of ketenimines with N-methoxybenzamides furnished 3-aminoisoindolin-1-ones and 3-(diarylmethylene)isoindolin-1-ones. The synthesized 3-(diarylmethylene)isoindolin-1-ones exhibited aggregation induced emissions in aqueous tetrahydrofuran solution and strong green-yellow emissions in solids.

Complexing properties of some carbamoylmethylphosphine oxides and methylenediphosphine dioxides with respect to alkali metal cations and the effect of abnormal aryl strengthening

International Nuclear Information System (INIS)

Evreinov, V.I.; Safronova, Z.V.; Yarkevich, A.N.; Kharitonov, A.V.; Bondarenko, N.A.; Tsvetkov, E.N.

1999-01-01

By the method of conductometry in anhydrous tetrahydrofuran at 25 Deg C stability constants of alkali metal (M = Li, Na, K) cation complexes with certain phosphinoxides have been determined. Abnormal aryl strengthening is first of all pronounced in the cation complexes with tetraphenyldiphosphine dioxide [ru

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Crystal structures of four green fluorescent protein (GFP) chromophore analogues with different packing interactions could be tuned by appropriate substitutions around the imidazolin-5-one ring are reported here. Compound 1 was crystallized from tetrahydrofuran at room temperature while compounds 2-4 have been ...

Pyridine-promoted dediazoniation of aryldiazonium tetrafluoroborates: Application to the synthesis of SF5-substituted phenylboronic esters and iodobenzenes

Directory of Open Access Journals (Sweden)

George Iakobson

2015-08-01

Full Text Available Pyridine promotes dediazoniation of aryldiazonium tetrafluoroborates. The formed aryl radicals were trapped with B2pin2, iodine, or tetrahydrofuran to afford boronic esters, iodobenzenes and benzenes, respectively. The application to the synthesis of (pentafluorosulfanylphenylboronic esters, iodo(pentafluorosulfanylbenzenes and (pentafluorosulfanylbenzene is shown.

Theoretical aspects of gradient reversed-phase high performance liquid chromatography of styrene-butylacrylate block copolymers

NARCIS (Netherlands)

Kolarova, L.; Jandera, P.; Vonk, E.C.; Claessens, H.A.

2004-01-01

Butylacrylate – styrene co-polymers prepared by atom transfer radical polymeratization were separated on an octadecyl silica column by gradient elution with tetrahydrofuran in water, up to the molar masses 10,000. In reversed-phase high performance liquid chromatography (RP-HPLC), the retention of

2-Alquil-4-Hidroxi-Tetrahidrofuranos de la Pulpa del Aguacate

Directory of Open Access Journals (Sweden)

Alfonso Rivas-Gil

2006-12-01

Full Text Available From a hexane extract of avocado pulp (Persea americana Mill., an 1:3 mixture of 2-(heptadec-16-enyl- and 2-(heptadec-16-ynyl-4-hydroxy -tetrahydrofurans was characterized by NMR techniques. These compounds have not been previously reported from natural sources.

Design and operation of a filter reactor for continuous production of a selected pharmaceutical intermediate

DEFF Research Database (Denmark)

Christensen, Kim Müller; Pedersen, Michael Jønch; Dam-Johansen, Kim

2012-01-01

in tetrahydrofuran solvent. The use of the filter reactor design was explored by examining the transferability of a synthesis step in a present full-scale semi-batch pharmaceutical production into continuous processing. The main advantages of the new continuous minireactor system, compared to the conventional semi...

"Hairy" Poly(3-hexylthiophene) Particles Prepared via Surface-Initiated Kumada Catalyst-Transfer Polycondensation

DEFF Research Database (Denmark)

Senkovskyy, Volodymyr; Tkachov, Roman; Beryozkina, Tetyana

2009-01-01

to the untethered counterparts (red shift and vibronic fine structure in absorption and fluorescence spectra), as a result of efficient planarization and chain-aggregation. These effects are observed in solvents that are normally recognized as good solvents for P3HT (e.g., tetrahydrofurane). We attribute...

Functionalization of Fluoroalkyl Polyhedral Oligomeric Silsesquioxanes (F-POSS) (Post Print)

Science.gov (United States)

2012-08-01

7Si7O9(ONa)3, has been derivatized with long-chain fluorinated trichlorosilanes to produce low surface energy materials (8). However, these shorter propyl ...such as tetrahydrofuran and chloroform . Currently a more in-depth analysis of these polymerizations is being undertaken. Figure 16. Static contact

Nanocellulose Derivative/Silica Hybrid Core-Shell Chiral Stationary Phase: Preparation and Enantioseparation Performance

Directory of Open Access Journals (Sweden)

Xiaoli Zhang

2016-05-01

Full Text Available Core-shell silica microspheres with a nanocellulose derivative in the hybrid shell were successfully prepared as a chiral stationary phase by a layer-by-layer self-assembly method. The hybrid shell assembled on the silica core was formed using a surfactant as template by the copolymerization reaction of tetraethyl orthosilicate and the nanocellulose derivative bearing triethoxysilyl and 3,5-dimethylphenyl groups. The resulting nanocellulose hybrid core-shell chiral packing materials (CPMs were characterized and packed into columns, and their enantioseparation performance was evaluated by high performance liquid chromatography. The results showed that CPMs exhibited uniform surface morphology and core-shell structures. Various types of chiral compounds were efficiently separated under normal and reversed phase mode. Moreover, chloroform and tetrahydrofuran as mobile phase additives could obviously improve the resolution during the chiral separation processes. CPMs still have good chiral separation property when eluted with solvent systems with a high content of tetrahydrofuran and chloroform, which proved the high solvent resistance of this new material.

Modified reaction mechanism of aerated n-dodecane liquid flowing over heated metal tubes

Science.gov (United States)

Reddy, K. T.; Cernansky, N. P.; Cohen, R. S.

1988-01-01

The degradation mechanism of the n-dodecane was studied using a modified jet fuel thermal oxidation tester containing a sample withdrawal system as a reaction vessel. The reaction products were identified using gas chromatography and mass spectorometry. The soluble products were found to consist mainly of C5-C10 n-alkanes and 1-alkenes, C7-C10 aldehydes, tetrahydrofuran derivatives, dodecanol and dodecanone isomers, dodecyl hydroperoxide (ROOH) decomposition products, and C24 alkane isomers. The data from the experiments agreed with those of Hazlett et al. (1977). It was found that alkyl peroxide radical reactions dominate in the autooxidation temperature regime (at T not above 300 C); the dominant path is for the alkyl peroxyl radical to react bimolecularly with fuel to yield primarily alkyl hydroperoxides. The alkyl peroxide radical also undergoes self-termination and unimolecular isomerization and decomposition reactions, to yield smaller amounts of C12 alcohol plus ketone products and tetrahydrofuran derivatives, respectively.

Unusual solvation through both p-orbital lobes of a carbene carbon

Energy Technology Data Exchange (ETDEWEB)

Hadad, C. Z., E-mail: cacier.hadad@udea.edu.co [Grupo de Química-Física Teórica, Instituto de Química, Universidad de Antioquia, A. A. 1226 Medellín (Colombia); Jenkins, Samantha [College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, Hunan 410081 (China); Flórez, Elizabeth [Departamento de Ciencias Básicas, Universidad de Medellín, Carrera 87 N° 30-65, Medellín (Colombia)

2015-03-07

As a result of a configurational space search done to explain the experimental evidence of transient specific solvation of singlet fluorocarbene amide with tetrahydrofuran, we found that the most stable structures consist in a group in which each oxygen of two tetrahydrofuran molecules act as electron donor to its respective empty p-orbital lobe of the carbene carbon atom, located at each side of the carbene molecular plane. This kind of species, which to our knowledge has not been reported before, explains very well the particular experimental characteristics observed for the transient solvation of this system. We postulate that the simultaneous interaction to both p-orbital lobes seems to confer a special stability to the solvation complexes, because this situation moves away the systems from the proximity of the corresponding transition states for the ylide products. Additionally, we present an analysis of other solvation complexes and a study of the nature of the involved interactions.

Accelerated solvent extraction of carotenoids from: Tunisian Kaki (Diospyros kaki L.), peach (Prunus persica L.) and apricot (Prunus armeniaca L.).

Science.gov (United States)

Zaghdoudi, Khalil; Pontvianne, Steve; Framboisier, Xavier; Achard, Mathilde; Kudaibergenova, Rabiga; Ayadi-Trabelsi, Malika; Kalthoum-Cherif, Jamila; Vanderesse, Régis; Frochot, Céline; Guiavarc'h, Yann

2015-10-01

Extraction of carotenoids from biological matrices and quantifications remains a difficult task. Accelerated solvent extraction was used as an efficient extraction process for carotenoids extraction from three fruits cultivated in Tunisia: kaki (Diospyros kaki L.), peach (Prunus persica L.) and apricot (Prunus armeniaca L.). Based on a design of experiment (DoE) approach, and using a binary solvent consisting of methanol and tetrahydrofuran, we could identify the best extraction conditions as being 40°C, 20:80 (v:v) methanol/tetrahydrofuran and 5 min of extraction time. Surprisingly and likely due to the high extraction pressure used (103 bars), these conditions appeared to be the best ones both for extracting xanthophylls such as lutein, zeaxanthin or β-cryptoxanthin and carotenes such as β-carotene, which present quite different polarities. Twelve surface responses were generated for lutein, zeaxanthin, β-cryptoxanthin and β-carotene in kaki, peach and apricot. Further LC-MS analysis allowed comparisons in carotenoids profiles between the fruits. Copyright © 2015 Elsevier Ltd. All rights reserved.

Isotopic effect in the hydration reactions of 2, 2, 2 - trichloro - 1 - arylethanones

International Nuclear Information System (INIS)

Marconi, D.O.M.; Zucco, C.; Tanaka, A.S.; Nome, F.

1985-01-01

The equilibrium constants and rate constants for hydration and de-hydration of 2, 2, 2 - trichloro - 1 - arylethanones in tetrahydrofurane (THF) / H 2 O - D 2 O e THF/H 2 O using the proton inventory technique involved in the transition state are studied. (M.J.C.) [pt

Improvement of polymer stability by radiation grafting

International Nuclear Information System (INIS)

Ranogajec, F.; Mlinac-Misak, M.

1999-01-01

Losses of the stabilizer due to extractability or volatility immediately affect ultimate performance of polymer product. A new approach to increase the persistence of the stabilizer in the final product is to chemically bind it to the polymer backbone. Radiation grafting or crosslinking could be an efficient method for this, when the stabilizer is polymerizable. By a mutual gamma irradiation method, photoprotector 2-hydroxy-4-(3-methacryloxy-2- hydroxy-propoxy) benzophenone (HMB) has been readily grafted to low density polyethylene (LDPE) in benzene, tetrahydrofuran and methanol solution, respectively. Surface grafting occurs in a methanol solution of stabilizer, while in benzene and tetrahydrofuran solutions of stabilizer, grafting proceeds more or less in the inner parts of the polymeric film as well. The grafted LDPE film in methanol and tetrahydrofuran (containing 1 w/w % of grafted HMB), 1 w/w % blended HMB with LDPE and nongrafted LDPE film, were all exposed to accelerated aging and natural weathering and their spectral changes, expressed by the carbonyl index, were then compared. The change of elongation at break and tensile strength were measured in the course of aging. UV stability tests on aged films and change in mechanical properties indicate a pronounced protective effect achieved by grafted stabilizer. Grafting in methanol solution appears to be an efficient photostabilization treatment and the most economical with respect to the consumption of monomer, the grafting yield being less than 0.5%. Surface grafting is an efficient photostabilization method since grafted stabilizer is chemically bound to a polymeric surface and in this way the problem of evaporation of blended stabilizers during the prolonged use of polymeric materials is eliminated. (author)

Synthesis and phytotoxicity of 4,5 functionalized tetrahydrofuran-2-ones

Energy Technology Data Exchange (ETDEWEB)

Resende, Gabriela C.; Alvarenga, Elson S., E-mail: elson@ufv.br [Universidade Federal de Vicosa (UFV), MG (Brazil). Dept. de Quimica; Galindo, Juan C.G.; Macias, Francisco A. [Grupo de Alelopatia, Departamento de Quimica Organica, Facultad de Ciencias, Universidad de Cadiz (Spain)

2012-12-15

In this work we report a versatile synthesis of fourteen {gamma}-lactones all structurally related, nine of which are novel compounds, accomplished from the readily available furfural. The phytotoxic activity of the synthesized compounds was evaluated in vitro by the influence on the growth of heat coleoptiles. The percentages of inhibition were mostly small and not statistically different from control after the third dilution (100 Greek-Small-Letter-Mu mol L{sup -1}). In general, {alpha},{beta}-unsaturated lactones presented better activities than the saturated ones. The most active compounds presented 51, 68 and 76% of inhibition in 1000 Greek-Small-Letter-Mu mol L-1. The results indicate that regardless of saturation, the presence of the {gamma}-lactone moiety is important for the bioactivity, but their presence has no implications with potency. (author)

Scandium complexes with the tetraphenylethylene and anthracene dianions.

Science.gov (United States)

Ellis, John E; Minyaev, Mikhail E; Nifant'ev, Ilya E; Churakov, Andrei V

2018-06-01

The structural study of Sc complexes containing dianions of anthracene and tetraphenylethylene should shed some light on the nature of rare-earth metal-carbon bonding. The crystal structures of (18-crown-6)bis(tetrahydrofuran-κO)sodium bis(η 6 -1,1,2,2-tetraphenylethenediyl)scandium(III) tetrahydrofuran disolvate, [Na(C 4 H 8 O) 2 (C 12 H 24 O 6 )][Sc(C 26 H 20 ) 2 ]·2C 4 H 8 O or [Na(18-crown-6)(THF) 2 ][Sc(η 6 -C 2 Ph 4 ) 2 ]·2(THF), (1b), (η 5 -1,3-diphenylcyclopentadienyl)(tetrahydrofuran-κO)(η 6 -1,1,2,2-tetraphenylethenediyl)scandium(III) toluene hemisolvate, [Sc(C 17 H 13 )(C 26 H 20 )(C 4 H 8 O)]·0.5C 7 H 8 or [(η 5 -1,3-Ph 2 C 5 H 3 )Sc(η 6 -C 2 Ph 4 )(THF)]·0.5(toluene), (5b), poly[[(μ 2 -η 3 :η 3 -anthracenediyl)bis(η 6 -anthracenediyl)bis(η 5 -1,3-diphenylcyclopentadienyl)tetrakis(tetrahydrofuran)dipotassiumdiscandium(III)] tetrahydrofuran monosolvate], {[K 2 Sc 2 (C 14 H 10 ) 3 (C 17 H 13 ) 2 (C 4 H 8 O) 4 ]·C 4 H 8 O} n or [K(THF) 2 ] 2 [(1,3-Ph 2 C 5 H 3 ) 2 Sc 2 (C 14 H 10 ) 3 ]·THF, (6), and 1,4-diphenylcyclopenta-1,3-diene, C 17 H 14 , (3a), have been established. The [Sc(η 6 -C 2 Ph 4 ) 2 ] - complex anion in (1b) contains the tetraphenylethylene dianion in a symmetrical bis-η 3 -allyl coordination mode. The complex homoleptic [Sc(η 6 -C 2 Ph 4 ) 2 ] - anion retains its structure in THF solution, displaying hindered rotation of the coordinated phenyl rings. The 1D 1 H and 13 C{ 1 H}, and 2D COSY 1 H- 1 H and 13 C- 1 H NMR data are presented for M[Sc(Ph 4 C 2 ) 2 ]·xTHF [M = Na and x = 4 for (1a); M = K and x = 3.5 for (2a)] in THF-d 8 media. Complex (5b) exhibits an unsymmetrical bis-η 3 -allyl coordination mode of the dianion, but this changes to a η 4 coordination mode for (1,3-Ph 2 C 5 H 3 )Sc(Ph 4 C 2 )(THF) 2 , (5a), in THF-d 8 solution. A 45 Sc NMR study of (2a) and UV-Vis studies of (1a), (2a) and (5a) indicate a significant covalent contribution to the Sc-Ph 4 C 2 bond character. The unique Sc ate complex, (6

Novel metabolic pathways for linoleic and arachidonic acid metabolism.

Science.gov (United States)

Moghaddam, M; Motoba, K; Borhan, B; Pinot, F; Hammock, B D

1996-08-13

Mouse liver microsomes oxidized linoleic acid to form 9,10- or 12,13-epoxyoctadecenoate. These monoepoxides were subsequently hydrolyzed to their corresponding diols in the absence of the microsomal epoxide hydrolase inhibitor, 1,2-epoxy-3,3,3-trichloropropane. Furthermore, both 9,10- and 12,13-epoxyoctadecenoates were oxidized to diepoxyoctadecanoate at apparently identical rates by mouse liver microsomal P-450 epoxidation. Both epoxyoctadecanoates and diepoxyoctadecanoates were converted to tetrahydrofuran-diols by microsomes. Tetrahydroxides of linoleate were produced as minor metabolites. Arachidonic acid was metabolized to epoxyeicosatrienoates, dihydroxyeicosatrienoates, and monohydroxyeicosatetraenoates by the microsomes. Microsomes prepared from clofibrate (but not phenobarbital) -treated mice exhibited much higher production rates for epoxyeicosatrienoates and vic-dihydroxyeicosatrienoates. This indicated an induction of P-450 epoxygenase(s) and microsomal epoxide hydrolase in mice by clofibrate and not by phenobarbital. Incubation of synthetic epoxyeicosatrienoates with microsomes led to the production of diepoxyeicosadienoates. Among chemically generated diepoxyeicosadienoate isomers, three of them possessing adjacent diepoxides were hydrolyzed to their diol epoxides which cyclized to the corresponding tetrahydrofuran-diols by microsomes as well as soluble epoxide hydrolase at a much higher rate. Larger cyclic products from non-adjacent diepoxides were not observed. The results of our in vitro experiments suggest that linoleic and arachidonic acid can be metabolized to their tetrahydrofuran-diols by two consecutive microsomal cytochrome P-450 epoxidations followed by microsomal or soluble epoxide hydrolase catalyzed hydrolysis of the epoxides. Incubation experiments with the S-9 fractions indicate that the soluble epoxide hydrolase is more important in this conversion. This manuscript is the first report of techniques for the separation and

Structural studies using X-ray absorption and scattering techniques

International Nuclear Information System (INIS)

Ericson, Agneta.

1989-01-01

The thesis presents extended X-ray absorption fine structure, EXAFS, and large angle X-ray scattering, LAXS, techniques; instrumentation, data collection and reduction, and applications. These techniques have been used to determine the structures of magnesium halides and organomagnesium halides in diethyl ether and tetrahydrofuran solution. The iodides were used for the LAXS measurements and Br K edge EXAFS data were collected for the corresponding bromides. Two different complexes are present in the diethyl ether solution of magnesium iodide; a polymeric chain-type structure where magnesium is tetrahedrally coordinated, as well as dimeric complex with octahedrally coordinated magnesium. Solvated MgI + is the dominating species in tetrahydrofuran solution. The organomagnesium halides are present in diethyl ether solution as both solvated monomeric and dimeric complexes. Magnesium coordinates a halide ion, an alkyl or aryl group and four solvent molecules octahedrally in the monomeric complex. In the dimeric complex magnesium is octahedrally coordinated by two bridging halide ions, an alkyl or aryl group and three solvent molecules. The distribution of monomeric and dimeric complexes in various solutions are given by a dimerisation constant, K dl . The results indicate that the Schlenk equilibrium is present in these solutions, however, in an extended form. In diethyl ether solution, where MgX 2 does not dissociate, no MgX 2 complex and thereby no Schlenk equilibrium has been observed. In tetrahydrofuran solution MgI 2 has dissociated into mainly MgI + and I - . This indicates that the concentration of MgI 2 is low and that the Schlenk equilibrium should be expanded even further to include the dissociation equilibrium of the magnesium halide. In the thesis Fe K edge EXAFS data collected for the semireduced form of protein A of methane monooxygenase from Methylococcus capsulatus, are also presented. (139 refs.)

The structure of active centers and the kinetic isotopic effect in the ionic polymerization of heterocyclic compounds

International Nuclear Information System (INIS)

Ponomarienko, W.A.; Berman, E.L.

1979-01-01

The method of kinetic isotopic effect has been applied to the elucidation of the structure of the active growth centres in the polymerization of some selected heterocyclic compounds. The cationic polymerization of ehtylene oxide, tetrahydrofuran and 1.3-dioxolane as well as the anionic and coordination polymerization of ethylene oxide have been discussed. (author)

and triorganotin(IV) complexes of 2-tert-butyl-4-methyl phenol

Indian Academy of Sciences (India)

TECS

-2-Me-4) have been synthesized by the reactions of di-n-butyl and dimethyltin dichlorides and tri-n-butyltin(IV) chloride with 2-tert-butyl-4-methylphenol and triethylamine in tetrahydrofuran. The reaction of triphenyltin chloride with trimethylsilyl-2-t-butyl-4- methylphenoxide in the same solvent however, gives a complex of ...

PVC/carbon nanotubes nanocomposites: evaluation of electrical resistivity and the residual solvent effect over the thermal properties of nanocomposites; Nanocompositos PVC/nanotubos de carbono: avaliacao da resistividade eletrica e efeito do solvente utilizado na obtencao dos nanocompositos nas propriedades termicas

Energy Technology Data Exchange (ETDEWEB)

Araujo, Rogerio Gomes [Instituto Superior Tupy (UNISOCIESC), Joinville, SC (Brazil); Pires, Alfredo T.N., E-mail: araujo@sociesc.org.br [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

2013-07-01

The procedure for obtaining nanocomposite by dispersing the nanoparticles in matrix polymer in solution with subsequent elimination of the solvent has been widely used, considering better efficiency in obtaining homogeneity of the final product. However, the presence of residual solvent may affect the nanocomposites in micro-and macroscopic properties of the product. The aim of this study was to evaluate the thermal properties of nanocomposites of poly(vinylchloride)/multi-walled carbon nanotube obtained from the polymer solution and dispersion of carbon nanotubes in tetrahydrofuran (THF), as well as the electrical resistivity of nanocomposites and the influence of residual solvent. The presence of residual tetrahydrofuran reduces the glass transition temperature (Tg) up to 26 °C, being independent of the amount of carbon nanotubes. The total elimination of the solvent is an important factor that does not induce changes in the properties of the polymeric matrix. The graft-COOH groups in the structure of the nanotubes leads to a considerable reduction of the electrical resistivity in ten orders of magnitude, from 0.4 %wt of nanotubes in the nanocomposite composition. (author)

Simultaneous determination of 18α-glycyrrhetinic acid and 18β-glycyrrhetinic acid in Glycyrrhiza glabra root by reversed phase high-performance liquid chromatography

Directory of Open Access Journals (Sweden)

Ambika Chamoli

2016-01-01

Full Text Available Background: The aim of the present research work is to develop a high-performance liquid chromatography (HPLC method for simultaneous analysis of 18α-glycyrrhetinic acid (18α-GA and 18β-GA (18β-GA of Glycyrrhiza glabra. Materials and Methods: About 20 μL aliquots of each 18α-GA and 18β-GA were analyzed using reversed-phase C-18 column. The mobile phase was acetonitrile:tetrahydrofuran:water (10:80:10, v/v/v. The run time was 10 min at flow rate of 1 ml/min. Ultraviolet detection was carried out at 254 nm. Results: 18α-GA and 18β-GA were well resolved in reversed phase C-18 column using mobile phase acetonitrile: tetrahydrofuran: water (10:80:10, v/v/v, pH 7.9. The Rtof 18α-GA and 18β-GA was detected at 2.091 and 2.377 min, respectively. Conclusion: The developed chromatography method could be extended for potential quantification or simultaneous determination of these markers in plant as well as in herbal formulation.

Hydroformylation of dihydrofurans catalyzed by rhodium complex encapsulated hexagonal mesoporous silica

KAUST Repository

Khokhar, Munir; Shukla, Ram S.; Jasra, Raksh Vir

2015-01-01

HRh(CO)(PPh3)3 encapsulated hexagonal mesoporous silica (HMS) is found to be an efficient heterogeneous catalyst for the selective hydroformylation of 2,3-dihydrofuran (2,3DHF) and 2,5-dihydrofuran (2,5DHF). The Rh-complex encapsulated in situ in the organic phase of template inside the pores of HMS was found to act as nano phase reactors. Conversion of 2,3-DHF and 2,5-DHF and selectivity of the corresponding aldehydes were thoroughly investigated by studying the reaction parameters: catalyst amount, substrate concentration, partial as well as total pressure of CO and H2, and temperature. The selectivity for the formation of tetrahydrofuran-2-carbaldehyde (THF-2-carbaldehyde) from the hydroformylation of 2,3-DHF was found to be more than the selectivity of the formation of tetrahydrofuran-3-carbaldehyde (THF-3-carbaldehyde) from 2,5-DHF. The reaction paths are suggested and discussed for the selective formation of the corresponding aldehydes. The catalyst was elegantly separated and effectively recycled for six times.

Improvement of the polymer stability by radiation grafting

International Nuclear Information System (INIS)

Ranogajec, F.; Mlinac-Misak, M.

2004-01-01

Losses of the stabilizer due to extractability or volatility immediately affect the ultimate performance of polymer products. A new approach to increase the persistence of the stabilizer in the final product is to chemically bind it to the polymer backbone. Radiation grafting or crosslinking could be an efficient method for this, when the stabilizer is polymerizable. By a mutual gamma irradiation method photoprotector 2-hydroxy-4-(3-methacryloxy-2-hydroxy-propoxy) benzophenone has been readily grafted to low-density polyethylene in benzene, tetrahydrofuran and methanol solution, respectively. Surface grafting occurs in a methanol solution of stabilizer, while in benzene and tetrahydrofuran solutions of the stabilizer, grafting proceeds more or less in the inner parts of the polymeric film as well. UV stability tests and changes in the mechanical properties of artificially and naturally aged films indicate pronounced protective effect achieved by the grafted stabilizer. Surface grafting is an efficient photostabilization method since the grafted stabilizer is chemically bound to a polymeric surface and in this way the problem of evaporation of blended stabilizers during the prolonged use of polymeric materials is eliminated

Hydroformylation of dihydrofurans catalyzed by rhodium complex encapsulated hexagonal mesoporous silica

KAUST Repository

Khokhar, Munir

2015-05-01

HRh(CO)(PPh3)3 encapsulated hexagonal mesoporous silica (HMS) is found to be an efficient heterogeneous catalyst for the selective hydroformylation of 2,3-dihydrofuran (2,3DHF) and 2,5-dihydrofuran (2,5DHF). The Rh-complex encapsulated in situ in the organic phase of template inside the pores of HMS was found to act as nano phase reactors. Conversion of 2,3-DHF and 2,5-DHF and selectivity of the corresponding aldehydes were thoroughly investigated by studying the reaction parameters: catalyst amount, substrate concentration, partial as well as total pressure of CO and H2, and temperature. The selectivity for the formation of tetrahydrofuran-2-carbaldehyde (THF-2-carbaldehyde) from the hydroformylation of 2,3-DHF was found to be more than the selectivity of the formation of tetrahydrofuran-3-carbaldehyde (THF-3-carbaldehyde) from 2,5-DHF. The reaction paths are suggested and discussed for the selective formation of the corresponding aldehydes. The catalyst was elegantly separated and effectively recycled for six times.

PVC/carbon nanotubes nanocomposites: evaluation of electrical resistivity and the residual solvent effect over the thermal properties of nanocomposites

International Nuclear Information System (INIS)

Araujo, Rogerio Gomes; Pires, Alfredo T.N.

2013-01-01

The procedure for obtaining nanocomposite by dispersing the nanoparticles in matrix polymer in solution with subsequent elimination of the solvent has been widely used, considering better efficiency in obtaining homogeneity of the final product. However, the presence of residual solvent may affect the nanocomposites in micro-and macroscopic properties of the product. The aim of this study was to evaluate the thermal properties of nanocomposites of poly(vinylchloride)/multi-walled carbon nanotube obtained from the polymer solution and dispersion of carbon nanotubes in tetrahydrofuran (THF), as well as the electrical resistivity of nanocomposites and the influence of residual solvent. The presence of residual tetrahydrofuran reduces the glass transition temperature (Tg) up to 26 °C, being independent of the amount of carbon nanotubes. The total elimination of the solvent is an important factor that does not induce changes in the properties of the polymeric matrix. The graft-COOH groups in the structure of the nanotubes leads to a considerable reduction of the electrical resistivity in ten orders of magnitude, from 0.4 %wt of nanotubes in the nanocomposite composition. (author)

Synthesis and Characterization of Furanic Compounds

Science.gov (United States)

2013-09-01

Furanamine. Solvent 2-Furanamine Acetone — Chloroform — Dimethylacetamide (DMAc) — Dimethylsulfoxide ( DMSO ) + Methanol ± Tetrahydrofuran (THF...4 Figure 4. 1 H NMR of 2-Furanamine in D2O solvent ...Spectra for the furanic compounds were obtained in a 0.1%–0.5% deuterated solvent solutions. 3. Synthesis 3.1 General The following monomers and

Lipophilic Super-Absorbent Swelling Gels as Cleaners for Use on Weapons Systems and Platforms

Science.gov (United States)

2014-02-01

Tetrahydrofuran (THF), isopropa- nol, acetonitrile, and dichloromethane were obtained from Acros Organics (Morris Plains, NJ). Dimethylsulfoxide ( DMSO ) and 1...1. In the following solvents , swelling degree did not change in both heating and cooling processes: water, DMSO , methanol, ethanol, isopropanol...available alkylstyrene copolymer (imbiber beads). The cleaning ability of the gels was compared with the standard solvent cleaner trichloroethylene

The extraction and determination of free lithium in Li-B alloys

International Nuclear Information System (INIS)

Kilroy, W.P.; Angres, I.

1979-01-01

Extraction of the lithium phase from lithium-rich Li-B alloys was achieved by reaction of the alloy with dry naphthalene dissolved in anhydrous tetrahydrofuran. The resulting radical anion was hydrolyzed and the lithium was determined by potentiometric titration from the moles of hydroxide formed. The composition of the Lisub(x)Bsub(y) residue was determined by difference. (Auth.)

Synthesis and investigation of saturated vapor pressure of lanthanum, praseodymium and neodymium tris-isopropylcyclopentadienyls

International Nuclear Information System (INIS)

Devyatykh, G.G.; Chernyaev, N.P.; Zverev, Yu.B.; Gavrishchuk, E.M.; Runovskaya, I.V.; Krupnova, Eh.F.; Chesnokova, S.G.

1980-01-01

Lanthanum, praseodymium and neodymium tris-isopropylcyclopentadienyls are synthesized with corresponding unhydrous chlorides in tetrahydrofuran solution. Saturated vapour pressure of substances obtained is studied in the 150-262 deg C range by the statistic method using a compensation zero-manometer. Vapour pressure of the compounds in question is shown to increase with the growth of the rare earth element number [ru

Liquid scintillation solution

International Nuclear Information System (INIS)

Long, E.C.

1976-01-01

The invention deals with a liquid scintillation solution which contains 1) a scintillation solvent (toluol), 2) a primary scintillation solute (PPO), 3) a secondary scintillation solute (dimethyl POPOP), 4) several surfactants (iso-octyl-phenol polyethoxy-ethanol and sodium di-hexyl sulfosuccinate) essentially different from one another and 5) a filter resolution and/or transparent-making agent (cyclic ether, especially tetrahydrofuran). (HP) [de

Quenching of excited uranyl ion during its photochemical reduction with triphenyl-phosphine : Part IV - effect of heterocyclic molecules

International Nuclear Information System (INIS)

Sidhu, M.S.; Bhatia, P.V.K.

1994-01-01

The presence of heterocyclic compounds triggers off a competition between photophysical and photochemical annihilation of excited uranyl ion during its photochemical reduction with triphenylphosphine. This competition is used to measure Stern-Volmer constant using UV visible spectrophotometer for quenching the uranyl ion luminescence with a number of heterocyclic molecules viz., pyridine, thiophene bipyridyl, tetrahydrofuran and piperidine. (author). 7 refs., 2 figs., 1 tab

Method of producing thin cellulose nitrate film

International Nuclear Information System (INIS)

Lupica, S.B.

1975-01-01

An improved method for forming a thin nitrocellulose film of reproducible thickness is described. The film is a cellulose nitrate film, 10 to 20 microns in thickness, cast from a solution of cellulose nitrate in tetrahydrofuran, said solution containing from 7 to 15 percent, by weight, of dioctyl phthalate, said cellulose nitrate having a nitrogen content of from 10 to 13 percent

Synthesis of Conformationally North-Locked Pyrimidine Nucleosides Built on an Oxabicyclo[3.1.0]hexane Scaffold | Center for Cancer Research

Science.gov (United States)

Beginning with a known 3-oxabicyclo[3.1.0]-hexane scaffold, the relocation of the fused cyclopropane ring bond and the shifting of the oxygen atom to an alternative location engendered a new 2-oxabicyclo[3.1.0]hexane template that mimics more closely the tetrahydrofuran ring of conventional nucleosides. The synthesis of this new class of locked nucleosides involved a novel

Volatile uranyl hexafluoroacetoacetonate complexes

International Nuclear Information System (INIS)

Dines, M.B.; Hall, R.B.; Kaldor, A.; Kramer, G.M.; Maas, E.T. Jr.

1980-01-01

A composition of matter is described, characterized by the formula UO 2 (CF 3 COCHCOCF 3 ).L where L is a ligand selected from isopropanol, ethanol, isobutanol, tert-butanol, methanol, tetrahydrofuran, acetone, dimethylformamide, n-propanol and ethyl acetate. A process for producing the complex comprises reacting uranyl chloride with a hexafluoroacetylacetonate dissolved in a ligand L: experimental details are given. (U.K.)

CHROMIUM(II) AMIDES - SYNTHESIS AND STRUCTURES

NARCIS (Netherlands)

EDEMA, JJH; GAMBAROTTA, S; MEETSMA, A; SPEK, AL; SMEETS, WJJ; CHIANG, MY

1993-01-01

A novel class of mono- and di-meric chromium(II) amides has been prepared and characterized. Reaction of [CrCl2(thf)2] (thf = tetrahydrofuran) with 2 equivalents of M(NR2) (R = C6H11, Pr(i), Ph, or phenothiazinyl; M = Li or Na) allowed the formation of the homoleptic amides [{Cr(mu-NR2)(NR2)}2] (R =

Cyclopentadienyl uranium, neptunium and plutonium chemistry

International Nuclear Information System (INIS)

Plews, M.J.

1985-01-01

The thesis presents the preparation and characterisation of a number of mono, bis and tris(cyclopentadienyl) complexes of uranium(IV), neptunium(IV) and plutonium(IV). The work of previous studies on mono(cyclopentadienyl) thorium and uranium complexes has been extended, and a range of isostructural neptunium species isolated. Their mode of formation and stability in tetrahydrofuran and acetonitrile solutions was investigated. (author)

Modification of solid-state property of sulfasalazine by using the supercritical antisolvent process

Science.gov (United States)

Wu, Wei-Yi; Su, Chie-Shaan

2017-02-01

In this study, the supercritical antisolvent (SAS) process was used to recrystallize an active pharmaceutical ingredient, sulfasalazine, to modify the solid-state properties including particle size, crystal habit and polymorphic form. Supercritical CO2 and tetrahydrofuran were used as the antisolvent and solvent, respectively. SAS results obtained from different operating temperatures (35, 45, 55 and 65 °C) were compared and discussed. The results indicate that at 55 °C, spherical sulfasalazine crystals were produced and that their mean particle size was micronized to approximately 1 μm. In addition, according to the analytical results of powder X-ray diffractometry (PXRD), a novel polymorphic form of sulfasalazine was obtained after SAS. Furthermore, the spectroscopic and thermal behavior of produced sulfasalazine crystals were also studied by Fourier transform infrared spectrometry (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Finally, SAS results obtained from different operating temperature was discussed on the basis of the mixture critical point (MCP) of CO2 and tetrahydrofuran. Operation at slightly higher than the MCP is favorable for recrystallization of sulfasalazine through SAS. These results demonstrate that the SAS process is an efficient tool for controlling and modifying the solid-state property of sulfasalazine.

Cellulose multilayer Membranes manufacture with Ionic liquid

KAUST Repository

Livazovic, Sara

2015-05-09

Membrane processes are considered energy-efficient for water desalination and treatment. However most membranes are based on polymers prepared from fossil petrochemical sources. The development of multilayer membranes for nanofiltration and ultrafiltration, with thin selective layers of naturally available cellulose has been hampered by the availability of non-aggressive solvents. We propose the manufacture of cellulose membranes based on two approaches: (i) silylation, coating from solutions in tetrahydrofuran, followed by solvent evaporation and cellulose regeneration by acid treatment; (ii) casting from solution in 1-ethyl-3-methylimidazolum acetate ([C2mim]OAc), an ionic liquid, followed by phase inversion in water. By these methods porous supports could be easily coated with semi-crystalline cellulose. The membranes were hydrophilic with contact angles as low as 22.0°, molecular weight cut-off as low as 3000 g mol-1 with corresponding water permeance of 13.8 Lm−2 h−1 bar−1. Self-standing cellulose membranes were also manufactured without porous substrate, using only ionic liquid as green solvent. This membrane was insoluble in water, tetrahydrofuran, hexane, N,N-dimethylformamide, 1-methyl-2-pyrrolidinone and N,N-dimethylacetamide.

Biofuel and chemical production by recombinant microorganisms via fermentation of proteinaceous biomass

Science.gov (United States)

Liao, James C.; Cho, Kwang Myung; Yan, Yajun; Huo, Yixin

2016-03-15

Provided herein are metabolically modified microorganisms characterized by having an increased keto-acid flux when compared with the wild-type organism and comprising at least one polynucleotide encoding an enzyme that when expressed results in the production of a greater quantity of a chemical product when compared with the wild-type organism. The recombinant microorganisms are useful for producing a large number of chemical compositions from various nitrogen containing biomass compositions and other carbon sources. More specifically, provided herein are methods of producing alcohols, acetaldehyde, acetate, isobutyraldehyde, isobutyric acid, n-butyraldehyde, n-butyric acid, 2-methyl-1-butyraldehyde, 2-methyl-1-butyric acid, 3-methyl-1-butyraldehyde, 3-methyl-1-butyric acid, ammonia, ammonium, amino acids, 2,3-butanediol, 1,4-butanediol, 2-methyl-1,4-butanediol, 2-methyl-1,4-butanediamine, isobutene, itaconate, acetoin, acetone, isobutene, 1,5-diaminopentane, L-lactic acid, D-lactic acid, shikimic acid, mevalonate, polyhydroxybutyrate (PHB), isoprenoids, fatty acids, homoalanine, 4-aminobutyric acid (GABA), succinic acid, malic acid, citric acid, adipic acid, p-hydroxy-cinnamic acid, tetrahydrofuran, 3-methyl-tetrahydrofuran, gamma-butyrolactone, pyrrolidinone, n-methylpyrrolidone, aspartic acid, lysine, cadeverine, 2-ketoadipic acid, and/or S-adenosyl-methionine (SAM) from a suitable nitrogen rich biomass.

Two novel solvent system compositions for protected synthetic peptide purification by centrifugal partition chromatography.

Science.gov (United States)

Amarouche, Nassima; Giraud, Matthieu; Forni, Luciano; Butte, Alessandro; Edwards, F; Borie, Nicolas; Renault, Jean-Hugues

2014-04-11

Protected synthetic peptide intermediates are often hydrophobic and not soluble in most common solvents. They are thus difficult to purify by preparative reversed-phase high-performance liquid chromatography (RP-HPLC), usually used for industrial production. It is then challenging to develop alternative chromatographic purification processes. Support-free liquid-liquid chromatographic techniques, including both hydrostatic (centrifugal partition chromatography or CPC) and hydrodynamic (counter-current chromatography or CCC) devices, are mainly involved in phytochemical studies but have also been applied to synthetic peptide purification. In this framework, two new biphasic solvent system compositions covering a wide range of polarity were developed to overcome solubility problems mentioned above. The new systems composed of heptane/tetrahydrofuran/acetonitrile/dimethylsulfoxide/water and heptane/methyl-tetrahydrofuran/N-methylpyrrolidone/water were efficiently used for the CPC purification of a 39-mer protected exenatide (Byetta®) and a 8-mer protected peptide intermediate of bivalirudin (Angiox®) synthesis. Phase compositions of the different biphasic solvent systems were determined by (1)H nuclear magnetic resonance. Physico-chemical properties including viscosity, density and interfacial tension of these biphasic systems are also described. Copyright © 2014 Elsevier B.V. All rights reserved.

Chemical clearing and dehydration of GFP expressing mouse brains.

Science.gov (United States)

Becker, Klaus; Jährling, Nina; Saghafi, Saiedeh; Weiler, Reto; Dodt, Hans-Ulrich

2012-01-01

Generally, chemical tissue clearing is performed by a solution consisting of two parts benzyl benzoate and one part benzyl alcohol. However, prolonged exposure to this mixture markedly reduces the fluorescence of GFP expressing specimens, so that one has to compromise between clearing quality and fluorescence preservation. This can be a severe drawback when working with specimens exhibiting low GFP expression rates. Thus, we screened for a substitute and found that dibenzyl ether (phenylmethoxymethylbenzene, CAS 103-50-4) can be applied as a more GFP-friendly clearing medium. Clearing with dibenzyl ether provides improved tissue transparency and strikingly improved fluorescence intensity in GFP expressing mouse brains and other samples as mouse spinal cords, or embryos. Chemical clearing, staining, and embedding of biological samples mostly requires careful foregoing tissue dehydration. The commonly applied tissue dehydration medium is ethanol, which also can markedly impair GFP fluorescence. Screening for a substitute also for ethanol we found that tetrahydrofuran (CAS 109-99-9) is a more GFP-friendly dehydration medium than ethanol, providing better tissue transparency obtained by successive clearing. Combined, tetrahydrofuran and dibenzyl ether allow dehydration and chemical clearing of even delicate samples for UM, confocal microscopy, and other microscopy techniques.

Vacuum ultraviolet photochemistry of tetrahydrothiophene and sulfolane

International Nuclear Information System (INIS)

Scala, A.A.; Colon, I.

1979-01-01

The vacuum uv photolysis of tetrahydrothiophene (THT) involves the breaking of the S to α-C bond. Besides ethylene, C 3 H 6 and 1,3-butadiene are also formed. Photolyses of THT, tetrahydrofuran, and pyrrolidine are similar. The vacuum uv photolysis of tetramethylene sulfone (sulfolane) was also studied; products are SO 2 , cyclobutane, 1-butene, and ethylene. No cis-2-butene was observed

Informal Conference on Photochemistry Held in Atlanta, Georgia on 26 April-1 May, 1992

Science.gov (United States)

1992-05-01

of the kinetics of such reactions. We have measured rate constants for the neopentyl peroxy radical, generating the alkyl radical by laser flash... glycol diacetate) > Ketones(acetone.acetophenone) > Ethers(tetrahydrofuran. dioxane). Nltrlles(acetonltrlle).Halogenated hydrocarbons (carbon...the best solvent to synthesis of CBDA. especially ethyl acetate (Y63% /KW Hr) and ethylene glycol diacetate (Y55,/lW Hr).i (2) TEMPERATURE CBDA yield

A facile approach for the synthesis of C13-C24 fragments of maltepolides A, C and D.

Science.gov (United States)

Rao, P Sankara; Srihari, P

2016-10-12

A linear, chiron approach for the synthesis of C13-C24 fragments of cytostatic maltepolides A, C and D consisting of a tetrahydrofuran subunit and a chiral alkenyl/alkyl substituent is achieved from (+)-diethyl l-tartrate. The other chiral stereocenters were generated by employing key reactions such as Crimmins aldol, alkynylation and CeCl 3 ·7H 2 O mediated Luche reduction reactions.

X-ray crystal and molecular structure of (eta/sup 5/C/sub 5/H/sub 5/)UCl/sub 3/. 2PPh/sub 3/O thf: trichloro (eta/sup 5/cyclopentadienyl)bis(triphenylphosphine oxide) uranium(IV). thf

Energy Technology Data Exchange (ETDEWEB)

Bombieri, G; De Paoli, G [Consiglio Nazionale delle Ricerche, Padua (Italy). Lab. di Chimica e Tecnologia dei Radioelementi; Del Pra, A; Bagnall, K W

1978-01-01

Following reports of the preparation of (eta/sup 5/C/sub 5/H/sub 5/)UCl/sub 3/.xL (x = 1, L = dimethoxyethane and x = 2, L = tetrahydrofuran (thf), a series of analogous oxygen-donor complexes were isolated. This paper describes the crystal and molecular structure of one of them, ((eta/sup 5/C/sub 5/H/sub 5/)UCl/sub 3/.2PPh/sub 3/O)thf.

Alkyne- and alkyl-tris(cyclopentadienyl) complexes of uranium(III)

International Nuclear Information System (INIS)

Foyentin, M.; Folcher, G.; Ephritkhine, M.

1987-01-01

Treatment of cp 3 U(THF) (1) (cp=eta-C 5 H 5 , THF=tetrahydrofuran) with diphenylacetylene affords the alkyne complex cp 3 U(Ph-C identical to C-Ph); (1) reacts with RLi (R = Me, Busup(n)) to give the alkyl compounds cp 3 URLi (3); hydrogenolysis of (3) in the presence of a terminal alkene R'(-H) leads to the formation of cp 3 UR'Li. (author)

Electrochemical selenium- and iodonium-initiated cyclisation of hydroxy-functionalised 1,4-dienes

Directory of Open Access Journals (Sweden)

Philipp Röse

2015-01-01

Full Text Available The cobalt(I-catalysed 1,4-hydrovinylation reaction of allyloxytrimethylsilane and allyl alcohol with substituted 1,3-dienes leads to hydroxy-functionalised 1,4-dienes in excellent regio- and diastereoselective fashion. Those 1,4-dienols can be converted into tetrahydrofuran and pyran derivatives under indirect electrochemical conditions generating selenium or iodonium cations. The reactions proceed in good yields and regioselectivities for the formation of single diastereomers.

Stereoselective total synthesis of the potent anti-asthmatic compound CMI-977 (LDP-977)

Energy Technology Data Exchange (ETDEWEB)

Dias, Luiz Carlos; Farina, Lui Strambi; Ferreira, Marco Antonio Barbosa, E-mail: ldias@iqm.unicamp.br [Universidade de Campinas (UNICAMP), SP (Brazil). Instituto de Quimica

2013-02-15

A short and efficient stereoselective total synthesis of CMI-977 (LDP-977), a potent and orally active anti-asthmatic compound, was developed. The key steps involve a highly diastereoselective Mukaiyama oxidative cyclization, which provides the trans-THF (tetrahydrofuran) unit and a Seyferth-Gilbert homologation to construct the triple bond in the target molecule. The synthesis of the key chiral building block was performed using Jacobsen hydrolytic kinetic resolution. (author)

Stereoselective total synthesis of the potent anti-asthmatic compound CMI-977 (LDP-977)

International Nuclear Information System (INIS)

Dias, Luiz Carlos; Farina, Lui Strambi; Ferreira, Marco Antonio Barbosa

2013-01-01

A short and efficient stereoselective total synthesis of CMI-977 (LDP-977), a potent and orally active anti-asthmatic compound, was developed. The key steps involve a highly diastereoselective Mukaiyama oxidative cyclization, which provides the trans-THF (tetrahydrofuran) unit and a Seyferth-Gilbert homologation to construct the triple bond in the target molecule. The synthesis of the key chiral building block was performed using Jacobsen hydrolytic kinetic resolution. (author)

Chemical clearing and dehydration of GFP expressing mouse brains.

Directory of Open Access Journals (Sweden)

Klaus Becker

Full Text Available Generally, chemical tissue clearing is performed by a solution consisting of two parts benzyl benzoate and one part benzyl alcohol. However, prolonged exposure to this mixture markedly reduces the fluorescence of GFP expressing specimens, so that one has to compromise between clearing quality and fluorescence preservation. This can be a severe drawback when working with specimens exhibiting low GFP expression rates. Thus, we screened for a substitute and found that dibenzyl ether (phenylmethoxymethylbenzene, CAS 103-50-4 can be applied as a more GFP-friendly clearing medium. Clearing with dibenzyl ether provides improved tissue transparency and strikingly improved fluorescence intensity in GFP expressing mouse brains and other samples as mouse spinal cords, or embryos. Chemical clearing, staining, and embedding of biological samples mostly requires careful foregoing tissue dehydration. The commonly applied tissue dehydration medium is ethanol, which also can markedly impair GFP fluorescence. Screening for a substitute also for ethanol we found that tetrahydrofuran (CAS 109-99-9 is a more GFP-friendly dehydration medium than ethanol, providing better tissue transparency obtained by successive clearing. Combined, tetrahydrofuran and dibenzyl ether allow dehydration and chemical clearing of even delicate samples for UM, confocal microscopy, and other microscopy techniques.

MYC RNAi-PT Combination Nanotherapy for Metastatic Prostate Cancer Treatment

Science.gov (United States)

2016-10-01

solvents on the siRNA NP self- assembly, including dimethylformamide (DMF), dimethylsulfoxide ( DMSO ), acetone, and tetrahydrofuran (THF). Figure 1b...polymer hybrid NPs for siRNA delivery, by systematically exploring (i) the effect of organic solvent on the NP formulation; (ii) the effect of surface...effect of organic solvent on the NP formulation; (ii) the effect of surface lipid-PEG on NP behaviors in vitro and in vivo; and (iii) the use of redox

Exploring endoperoxides as a new entry for the synthesis of branched azasugars

DEFF Research Database (Denmark)

Domeyer, Svenja; Bjerregaard, Mark; Johansson, Henrik

2017-01-01

A new class of nitrogen-containing endoperoxides were synthesised by a photochemical [4 + 2]-cycloaddition between a diene and singlet oxygen. The endoperoxides were dihydroxylated and protected to provide a series of endoperoxide building blocks for organic synthesis, with potential use as precu...... as precursors for the synthesis of branched azasugars. Preliminary exploration of the chemistry of these building blocks provided access to a variety of derivatives including tetrahydrofurans, epoxides and protected amino-tetraols....

スチレン/セルロースグラフト化生成物から得たトルエン抽出物の界面活性

OpenAIRE

多賀, 透

2000-01-01

Styrene was grafted onto the cellulose gel made from a phosphoric acid solution of cellulose. Toluene extraction was carried out on the graft product at room temperature after removing homo polystyrene by means of tetrahydrofuran extraction. The toluene solutions of the extracts constituted of polystyrene and cellulose were dispersed in 85% phosphoric acid, forming emulsion systems. The interfacial tension between two macroscopic phases, i.e. a clear toluene phase and a transparent phosphoric...

Dihydroxylation of 4-substituted 1,2-dioxines

DEFF Research Database (Denmark)

Robinson, Tony V; Pedersen, Daniel Sejer; Taylor, Dennis K

2009-01-01

The synthesis of 2-C-branched erythritol derivatives, including the plant sugar (+/-)-2-C-methylerythritol 2, was achieved through a dihydroxylation/reduction sequence on a series of 4-substituted 1,2-dioxines 3. The asymmetric dihydroxylation of 1,2-dioxines was examined, providing access...... to optically enriched dihydroxy 1,2-dioxanes 4. The synthesized 1,2-dioxanes were converted to other erythro sugar analogues and tetrahydrofurans through controlled cleavage of the endoperoxide linkage....

Small angle X-ray scattering study on the conformation of polystyrene in the anti-solvent process of supercritical fluids

International Nuclear Information System (INIS)

Liu Yi; Wang Hongli; Zhao Xin; Chen Na; Li Dan; Liu Zhimin; Han Buxing; Rong Lixia; Zhao Hui; Wang Jun; Dong Baozhong

2003-01-01

The conformation of polystyrene in the anti-solvent process of supercritical fluids (compressed CO 2 + polystyrene + tetrahydrofuran) is studied by synchrotron radiation X-ray small angle scattering (SAXS). Coil-to-globule transform of polystyrene chain is observed with increasing the concentration of CO 2 . It is found that polystyrene coils at the pressure lower than cloud point pressure (p c ) and changes into globule with uniform density at the pressure higher than p c

A new efficient and stereospecific conversion of aminodeoxyalditols into aminoalkyl-substituted tetrahydrofurans

DEFF Research Database (Denmark)

Norrild, Jens Chr.; Pedersen, Christian; Defaye, Jacques

1996-01-01

Reaction of a series of aminodeoxy-pentitols and -hexitols in anhydrous hydrogen fluoride with formic acid as catalyst gave the corresponding 2,5- and 3,6-anhydro-anlinodeoxyalditols; namely, 1-amino-2,5-anhydro-1-deoxy-D-arabinitol, -D-xylitol, and -D-ribitol; 1-amino-3,6-anhydro-1-deoxy......-trimethylammonio-D-gulitol chloride. D-arabino-Hexosulose phenylosotriazole gave the corresponding 3,6-anhydro-D-avabino-hexosulose phenylosotriazole. Syntheses of the 1-amino-1-deoxyalditols were performed by reductive amination with benzylamine-sodium borohydride followed by catalytic hydrogenation over Pd-C. (C...

Effect of various experimental parameters on the swelling and supercritical extraction properties of lignite

Energy Technology Data Exchange (ETDEWEB)

Hacimehmetoglu, S.; Sinag, A.; Tekes, A.T.; Misirlioglu, Z.; Canel, M. [Ankara University, Ankara (Turkey). Faculty of Science

2007-07-01

The original lignite sample, the samples swollen in dimethylsulfoxide (DMSO), dimethylformamide (DMF), pyridine, tetrahydrofuran (THF), acetone, ethylenediamine (EDA), N-methyl-2-pyrrolidone (NMP), tetrabutylammonium hydroxide (TBAH), the samples impregnated by ZnCl{sub 2} as catalyst and the samples both swollen in the solvents and impregnated by ZnCl{sub 2} were subjected to the supercritical toluene extraction and the effects of temperature, pressure, pre-swelling procedure, hydrogen donor solvent (tetralin), and catalyst on the extract yields were investigated.

Efficient synthesis of substituted uranocenes

International Nuclear Information System (INIS)

Miller, J.T.; DeKock, C.W.

1979-01-01

Dilithium n-butylcyclooctatetraenide is prepared by reaction of 2 equiv of n-butyllithium with 1 equiv of cyclooctatetraene in diethyl ether at 25 0 C. Treatment of this solution with 0.5 equiv of UCl 4 dissolved in tetrahydrofuran followed by Soxhlet extraction with hexane resulted in a 50% yield of 1,1'-di-n-butyluranocene based on cyclooctatetraene. Treatment of 1,1'-di-n-butyluranocene with nitrobenzene resulted in a 51% yield of azobenzene based on cyclooctatetraene

Polar-Nonpolar Radical Copolymerization under Li+ Catalysis

Science.gov (United States)

2008-09-21

bonds or aromatic rings. Thus, we propose that a transfer of a methyl radical from CB11Me12C to IB triggers a radical polymerization chain that yields ...b-PIB and the resulting CB11Me11 byproduct concurrently triggers a cationic polymerization chain that yields l-PIB terminated with a carborate anion...tetrahydrofuran and passed through a column of alumina about five times to remove the bulk of the catalyst. A Soxhlet apparatus was used to recover

Measurement and correlation of solubility of trans-resveratrol in 11 solvents at T = (278.2, 288.2, 298.2, 308.2, and 318.2) K

Energy Technology Data Exchange (ETDEWEB)

Sun Xilan; Peng Bin [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Yan Weidong [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China)], E-mail: yanweidong@zju.edu.cn

2008-04-15

The solubilities of trans-resveratrol in methanol, ethanol, 1-propanol, 2- propanol, 1-butanol, 1-pentanol, 1-hexanol, ethyl acetate, tetrahydrofuran, acetone, and water (pH 6.0) solvents were measured at T = (278.2, 288.2, 298.2, 308.2, and 318.2) K. The solubilities of trans-resveratrol in selected solvents increase with temperature, but decrease with increasing the number of carbon in alcohol solvents. The experimental data were correlated using a thermodynamic equation.

Measurement and correlation of solubility of trans-resveratrol in 11 solvents at T = (278.2, 288.2, 298.2, 308.2, and 318.2) K

International Nuclear Information System (INIS)

Sun Xilan; Peng Bin; Yan Weidong

2008-01-01

The solubilities of trans-resveratrol in methanol, ethanol, 1-propanol, 2- propanol, 1-butanol, 1-pentanol, 1-hexanol, ethyl acetate, tetrahydrofuran, acetone, and water (pH 6.0) solvents were measured at T = (278.2, 288.2, 298.2, 308.2, and 318.2) K. The solubilities of trans-resveratrol in selected solvents increase with temperature, but decrease with increasing the number of carbon in alcohol solvents. The experimental data were correlated using a thermodynamic equation

Studies on single polymer composites of poly(methyl methacrylate) reinforced with electrospun nanofibers with a focus on their dynamic mechanical properties

CSIR Research Space (South Africa)

Matabola, KP

2011-07-01

Full Text Available by dynamic mechanical analyser (DMA). 2. Experimental 2.1. Materials High molecular weight PMMA (PMMAhigh, Mw = 996 000 g/mol) was purchased from Sigma Aldrich (Schenelldorf, Germany). N,N-dimethylformamide (DMF) and tetrahydrofuran (THF) were obtained...% PMMA in a 1:1 THF:DMF solvent mixture. The electrospun PMMAhigh nanofibers were used as the reinforcing phase and a low molecular weight PMMA (PMMAlow, 90 000 g/mol, Altuglass V825- TL grade) purchased from Advanced Polymers (Altuglass...

Neutral complexes of the indium dihalides

Energy Technology Data Exchange (ETDEWEB)

Sinclair, I.; Worrall, I.J. (Lancaster Univ. (UK))

1982-03-15

The neutral complexes In/sub 2/X/sub 4/.2L (X=Cl, Br, I; L 1,4-dioxan, tetrahydropyran, tetrahydrofuran, tetrahydrothiophene), In/sub 2/X/sub 4/.2L (X=Br, I; Ldimethylsulphide), In/sub 2/X/sub 4/.4L (X=Cl, Br, I; Lpiperidine, piperazine, morpholine), and In/sub 2/X/sub 4/.4L (X=Br, I; L=pyridine, dimethylsulphoxide) have been prepared. Solid state Raman spectra indicate that the compounds contain indium-indium bonds.

Liquid scintillation solutions

International Nuclear Information System (INIS)

Long, E.C.

1976-01-01

The liquid scintillation solution described includes a mixture of: a liquid scintillation solvent, a primary scintillation solute, a secondary scintillation solute, a variety of appreciably different surfactants, and a dissolving and transparency agent. The dissolving and transparency agent is tetrahydrofuran, a cyclic ether. The scintillation solvent is toluene. The primary scintillation solute is PPO, and the secondary scintillation solute is dimethyl POPOP. The variety of appreciably different surfactants is composed of isooctylphenol-polyethoxyethanol and sodium dihexyl sulphosuccinate [fr

Effect of solvent on cocrystallization of Es2+ with SrCl2

International Nuclear Information System (INIS)

Mikheev, N.B.; Veleshko, I.E.; Kulyukhin, S.A.

1994-01-01

Complexation of Es 2+ with tetraphenylborate (BPh 4 - ) in acetonitrile (CH 3 CN) and tetrahydrofuran (THF) is studied by cocrystallization. The dependence of the cocrystallization coefficients of Es 2+ on [LiBPh 4 ] demonstrated that in THF, in contrast with CH 3 CN, Es 2+ is not complexed by BPh 4 . The stability constants β 1 and β 2 of the Es 2+ -BPh 4 complexes are 6.6 and 16.0, respectively, in CH 3 CN

Synthesis of analogues of Eunicea gamma-cembranolides containing cyclic ethers via saponification.

Science.gov (United States)

Rodríguez, A D; Piña, I C; Acosta, A L; Ramírez, C; Soto, J J

2001-02-09

A method for the synthesis of derivatives of the lead structures euniolide (1), 12,13-bisepieupalmerin (2), and eupalmerin acetate (3) containing tetrahydrofuran and tetrahydropyran ring systems was developed on the basis of alkali-induced intramolecular oxacyclizations. Representatives of the new analogues were submitted to the in vitro antitumor cell-line-screening program of the National Cancer Institute (NCI). While it was shown that a variety of structural modifications are possible, these transformations led typically to nontoxic synthetic cembranoids.

Electrolyte for stable cycling of high-energy lithium sulfur redox flow batteries

Science.gov (United States)

Xiao, Jie; Liu, Jun; Pan, Huilin; Henderson, Wesley A.

2018-04-24

A device comprising: a lithium sulfur redox flow battery comprising an electrolyte composition comprising: (i) a dissolved Li2Sx electroactive salt, wherein x.gtoreq.4; (ii) a solvent selected from dimethyl sulfoxide, tetrahydrofuran, or a mixture thereof; and (iii) a supporting salt at a concentration of at least 2 M, as measured by moles of supporting salt divided by the volume of the solvent without considering the volume change of the electrolyte after dissolving the supporting salt.

Detection Identification and Quantification of Keto-Hydroperoxides in Low-Temperature Oxidation.

Energy Technology Data Exchange (ETDEWEB)

Hansen, Nils; Moshammer, Kai; Jasper, Ahren W.

2017-07-01

Keto-hydroperoxides are reactive partially oxidized intermediates that play a central role in chain-branching reactions during the low-temperature oxidation of hydrocarbons. In this Perspective, we outline how these short lived species can be detected, identified, and quantified using integrated experimental and theoretical approaches. The procedures are based on direct molecular-beam sampling from reactive environments, followed by mass spectrometry with single-photon ionization, identification of fragmentation patterns, and theoretical calculations of ionization thresholds, fragment appearance energies, and photoionization cross sections. Using the oxidation of neo-pentane and tetrahydrofuran as examples, the individual steps of the experimental approaches are described in depth together with a detailed description of the theoretical efforts. For neo-pentane, the experimental data are consistent with the calculated ionization and fragment appearance energies of the keto-hydroperoxide, thus adding confidence to the analysis routines and the employed levels of theory. For tetrahydrofuran, multiple keto-hydroperoxide isomers are possible due to the presence of nonequivalent O₂ addition sites. Despite this additional complexity, the experimental data allow for the identification of two to four keto-hydroperoxides. Mole fraction profiles of the keto-hydroperoxides, which are quantified using calculated photoionization cross sections, are provided together with estimated uncertainties as function of the temperature of the reactive mixture and can serve as validation targets for chemically detailed mechanisms.

Size characterization of metal oxide nanoparticles in commercial sunscreen products

Science.gov (United States)

Bairi, Venu Gopal; Lim, Jin-Hee; Fong, Andrew; Linder, Sean W.

2017-07-01

There is an increase in the usage of engineered metal oxide (TiO2 and ZnO) nanoparticles in commercial sunscreens due to their pleasing esthetics and greater sun protection efficiency. A number of studies have been done concerning the safety of nanoparticles in sunscreen products. In order to do the safety assessment, it is pertinent to develop novel analytical techniques to analyze these nanoparticles in commercial sunscreens. This study is focused on developing analytical techniques that can efficiently determine particle size of metal oxides present in the commercial sunscreens. To isolate the mineral UV filters from the organic matrices, specific procedures such as solvent extraction were identified. In addition, several solvents (hexane, chloroform, dichloromethane, and tetrahydrofuran) have been investigated. The solvent extraction using tetrahydrofuran worked well for all the samples investigated. The isolated nanoparticles were characterized by using several different techniques such as transmission electron microscopy, scanning electron microscopy, dynamic light scattering, differential centrifugal sedimentation, and x-ray diffraction. Elemental analysis mapping studies were performed to obtain individual chemical and morphological identities of the nanoparticles. Results from the electron microscopy techniques were compared against the bulk particle sizing techniques. All of the sunscreen products tested in this study were found to contain nanosized (≤100 nm) metal oxide particles with varied shapes and aspect ratios, and four among the 11 products were showed to have anatase TiO2.

Preparation and study of properties of dispersed graphene oxide

Directory of Open Access Journals (Sweden)

Evgeniya Seliverstova

2015-09-01

Full Text Available Ability of graphene oxide to form stable dispersion in organic solvents was studied in this work. As it was shown, sonication of graphene leads to the decreas of the particle size. Stability of prepared graphene dispersions was studied upon measurements of distribution of number of the particles via size and change of optical density of the solutions with time. It was found that graphene oxide forms a more stable dispersion in tetrahydrofuran and dimethylformamide than in chloroform and acetone.

A general approach for the synthesis of bimetallic M–Sn (M = Ru, Rh and Ir) catalysts for efficient hydrogenolysis of ester

KAUST Repository

Samal, Akshaya Kumar

2016-11-24

A versatile synthetic method was applied for the preparation of Sn containing bimetallic catalysts. The synthesis was performed by simply mixing the super hydride [LiB(C2H5)(3)H], with a metal (Ru, Rh or Ir) salt and an organotin complex in tetrahydrofuran solvent without using any surfactant. This leads to the formation of monodispersed M-Sn (M = Ru, Rh or Ir) bimetallic nanoparticles (NPs). These bimetallic catalysts show high performances in the hydrogenolysis of ester to the corresponding alcohol.

9-{[4-(Dimethylaminobenzyl]amino}-5-(4-hydroxy-3,5-dimethoxyphenyl-5,5a,8a,9-tetrahydrofuro[3′,4′:6,7]naphtho[2,3-d][1,3]dioxol-6(8H-one methanol monosolvate

Directory of Open Access Journals (Sweden)

Hong Chen

2011-11-01

Full Text Available In the title compound, C30H32N2O7·CH4O, the tetrahydrofuran ring and the six-membered ring fused to it both display envelope conformations, with the ring C atom opposite the carbonyl group and the adjacent bridgehead C atom as the flaps, respectively. In the crystal structure, intermolecular O—H...O hydrogen bonds link all moieties into ribbons along [010]. Weak intermolecular C—H...O interactions consolidate the crystal packing further.

Synthesis, properties, and crystal structure of complex Cp2Yb(DAD)

International Nuclear Information System (INIS)

Trifonov, A.A.; Kirillov, E.N.; Bochkarev, M.N.; Shumani, G.; Myule, S.

1999-01-01

Diazadiene complex of trivalent ytterbium Cp 2 Yb(DAD) (1) (DAD = Bu 1 -N CH-CH = N-Bu 1 ) was obtained by three routes: the oxidation of Cp 2 Yb(THF) 2 by diazadiene in tetrahydrofuran (THF), the reaction of Cp 2 YbCl with DAD 2- Na 2 + (2:1), and the reaction of Cp 2 YbCl(THF) with DAD - K + in the 1:1 ratio. Complex 1 was characterized by microanalysis, IR spectroscopy, magnetochemistry, and X-ray structural analysis [ru

Electrolyte for stable cycling of high-energy lithium sulfur redox flow batteries

Energy Technology Data Exchange (ETDEWEB)

Xiao, Jie; Liu, Jun; Pan, Huilin; Henderson, Wesley A.

2018-04-24

A device comprising: a lithium sulfur redox flow battery comprising an electrolyte composition comprising: (i) a dissolved Li₂S_x electroactive salt, wherein x.gtoreq.4; (ii) a solvent selected from dimethyl sulfoxide, tetrahydrofuran, or a mixture thereof; and (iii) a supporting salt at a concentration of at least 2 M, as measured by moles of supporting salt divided by the volume of the solvent without considering the volume change of the electrolyte after dissolving the supporting salt.

Use of deuterium n. m. r. spectroscopy in mechanistic studies of exchange reactions of ethers on supported metal catalysts

Energy Technology Data Exchange (ETDEWEB)

Campbell, J.A.; Kemball, Charles; McDougall, G.S.

1987-10-01

Exchange reactions of diethyl ether (DEE) and tetrahydrofuran (THF) with deuterium have been studied over supported nickel, palladium, platinum, and rhodium catalysts. Products from most of the systems were analysed by deuterium n.m.r. spectroscopy (55.28 MHz) which gave quantitative results about the distribution of deuterium in the exchanged ethers. The results confirm earlier conclusions about the mechanism of the exchange of DEE and provide new evidence about the reactions of THF. Some hydrogenolysis occurred simultaneously with exchange of THF over both nickel and platinum.

Method of synthesizing tungsten nanoparticles

Science.gov (United States)

Thoma, Steven G; Anderson, Travis M

2013-02-12

A method to synthesize tungsten nanoparticles has been developed that enables synthesis of nanometer-scale, monodisperse particles that can be stabilized only by tetrahydrofuran. The method can be used at room temperature, is scalable, and the product concentrated by standard means. Since no additives or stabilizing surfactants are required, this method is particularly well suited for producing tungsten nanoparticles for dispersion in polymers. If complete dispersion is achieved due to the size of the nanoparticles, then the optical properties of the polymer can be largely maintained.

Robotized synthesis of [3-11C]-L-alanine using reaction of asymmetric alkylation of 11CH3I nickel complex of glycine Schiff base with S-2-N-(N'-benzylpropyl)aminobenzophenone

International Nuclear Information System (INIS)

Mosevich, I.K.; Kuznetsova, O.F.; Vasil'ev, D.A.; Anichkov, A.A.; Korsakov, M.V.

1999-01-01

Synthesis of [3- 11 C]-L-alanine based on 11 CH 3 I nickel complex (1) alkylation using different solvents (tetrahydrofuran, dimethylformamide, acetonitrile, acetone) and catalysts (potassium butylate, sodium hydride) was investigated. It was shown that synthesis of amino acids labelled with 11 C based on complex (1) use permits to obtain preparations with high degree of enantiomeric enrichment. The best results (enantiomeric excess of L-alanine up to 99 %) were obtained in reaction with acetonitrile as a solvent and potassium tret-butylate as a catalyst

Redetermination of di-μ-hydrido-hexahydridotetrakis(tetrahydrofurandialuminium(IIImagnesium(II

Directory of Open Access Journals (Sweden)

Hima Kumar Lingam

2010-05-01

Full Text Available The structure of the title compound, [Mg(AlH42(C4H8O4], has been redetermined at 150 K. The MgII ion is hexacoordinated to four tetrahydrofuran (THF ligands, and two AlH4− anions through bridging H atoms. The Al—H distances are more precise compared to those previously determined [Nöth et al. (1995. Chem. Ber. 128, 999–1006; Fichtner & Fuhr (2002. J. Alloys Compd, 345, 386–396]. The molecule has twofold rotation symmetry.

Stereosequence distributions of poly(t-butyl methacrylate)s prepared with butyllithium

International Nuclear Information System (INIS)

Suzuki, Toshimitsu; Yamada, Osamu; Watanabe, Yoshihisa; Takegami, Yoshinobu

1982-01-01

13 C NMR spectra of poly(t-butyl methacrylate)s (PBMA) prepared with butyl-lithium (n-BuLi) were studied. Methylene carbon resonances appeared as five overlapped peaks, which were interpreted as a combination of hexad stereosequence distributions. The stereosequence distribution of PBMA prepared with n-BuLi at -78 0 C obeyed the first order Markov chain model even polymerized in tetrahydrofuran (THF). Syndiotactic PBMA was obtained with azobisisobutyronitrile (AIBN) as the initiator, and the stereosequence distribution of this polymer agreed well with Bernoullian statistics. (author)

Synthesis, crystal structure, and photoluminescence of a lithium isothiocyanate compound with 18-crown-6

Energy Technology Data Exchange (ETDEWEB)

Fu, Shan; Fu, Bo; Zhao, Zhen; Liu, Xi [Chongqing Normal Univ. (China). Chongqing Key Lab. of Inorganic Functional Materials

2018-04-01

The investigation of the supramolecular interactions between the lithium isothiocyanate salt and 18-crown-6 (18C-6) in commercial tetrahydrofuran leads to the formation of a lithium compound, LiNCS(H{sub 2}O)(18C-6) (1). In the crystal structure the asymmetric unit contains two similar LiNCS(H{sub 2}O)(18C-6) molecules. Solid-state photoluminescence experiments have shown that compound 1 emits violet luminescence, and its possible emission mechanism was investigated in detail based on theoretical calculations.

Molecular mechanism of short-patch repair of radiation-damaged DNA by in vitro reconstituted systems

International Nuclear Information System (INIS)

Matsumoto, Y.; Kim, K.; Biade, S.

1995-01-01

Objective: Short-patch excision repair is the major pathway to correct DNA damage such as modified bases, apurinic/apyrimidinic (AP) sites and single-strand breaks. Recently this repair reaction was demonstrated to proceed by two alternative pathways: DNA polymerase β (pol β)-dependent pathway and proliferating cell nuclear antigen (PCNA)-dependent pathway. In this work, we focused to compare substrate specificity of these two repair pathways and elucidate their roles in cellular responses to radiation damage. Materials and Methods: Three protein fractions, AP endonuclease, pol β, and BE-1B, which are required for the pol β-dependent pathway, and five protein fractions, AP endonuclease, BE-1B (these two are common to the pol β-dependent pathway), PCNA, pol δ, and BE-2, which are essential for the PCNA-dependent pathway were obtained from Xenopus laevis ovaries through column chromatography. The circular DNA containing either one of the following three lesions: a natural AP site, its synthetic analog, 3-hydroxy-2-hydroxymethyltetrahydrofuran (tetrahydrofuran), and 5-iododeoxyuridine (IdU), was prepared by in vitro ligation of oligonucleotides to a gapped circular DNA. The IdU-containing DNA was irradiated with 312 nm UV light prior to repair reaction. In addition, DNA carrying a single-strand break was obtained by Cs-137 irradiation. Repair reactions of these substrate DNAs were conducted with either the reconstituted system for the pol β-dependent pathway or the one for the PCNA-dependent pathway. After the reaction, repaired and unrepaired DNAs were separated by gel electrophoresis and quantitated. Results: The pol β-dependent reconstituted system was able to repair natural AP sites but not tetrahydrofuran sites or UV-irradiated IdU. The single-strand breaks generated by γ-irradiation were partially repaired by thepol β-dependent pathway. The PCNA-dependent system was able to repair natural AP sites, tetrahydrofuran sites, and most of the single

Synthetic oligomer analysis using atmospheric pressure photoionization mass spectrometry at different photon energies

International Nuclear Information System (INIS)

Desmazières, Bernard; Legros, Véronique; Giuliani, Alexandre; Buchmann, William

2014-01-01

Graphical abstract: Atmospheric pressure photoIonization mass spectra of synthetic oligomers were recorded in the negative mode by varying the photon energy using synchrotron radiation. Photon energy required for an efficient ionization of the polymer was correlated to ionization potential of the solvent (for example 9.4 eV for tetrahydrofuran). -- Highlights: •Atmospheric pressure photoionization was performed using synchrotron radiation. •Photoionization of oligomers in THF with 10% CH 2 Cl 2 produces intact [M + Cl] − ions. •The photon energy required corresponds to ionization potential of the solvent. •Polymer distributions depend on source parameters such T °C and applied voltages. •Liquid chromatography was coupled to MS using an APPI interface for polymer analysis. -- Abstract: Atmospheric pressure photoionization (APPI) followed by mass spectrometric detection was used to ionize a variety of polymers: polyethylene glycol, polymethyl methacrylate, polystyrene, and polysiloxane. In most cases, whatever the polymer or the solvent used (dichloromethane, tetrahydrofuran, hexane, acetone or toluene), only negative ion mode produced intact ions such as chlorinated adducts, with no or few fragmentations, in contrast to the positive ion mode that frequently led to important in-source fragmentations. In addition, it was shown that optimal detection of polymer distributions require a fine tuning of other source parameters such as temperature and ion transfer voltage. Series of mass spectra were recorded in the negative mode, in various solvents (dichloromethane, tetrahydrofuran, hexane, toluene, and acetone), by varying the photon energy from 8 eV up to 10.6 eV using synchrotron radiation. To these solvents, addition of a classical APPI dopant (toluene or acetone) was not necessary. Courtesy of the synchrotron radiation, it was demonstrated that the photon energy required for an efficient ionization of the polymer was correlated to the ionization energy

Synthetic oligomer analysis using atmospheric pressure photoionization mass spectrometry at different photon energies

Energy Technology Data Exchange (ETDEWEB)

Desmazières, Bernard [Global Bioenergies, 5 rue Henri Desbruyeres, 91030 Evry (France); Legros, Véronique [CNRS, UMR8587, Université d’Evry-Val-d’Essonne, Laboratoire Analyse et Modélisation pour la Biologie et l’Environnement, F-91025 Evry (France); Giuliani, Alexandre [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, 91192 Gif-sur-Yvette (France); UAR1008, CEPIA, INRA, Rue de la Geraudiere, F-44316 Nantes (France); Buchmann, William, E-mail: william.buchmann@univ-evry.fr [CNRS, UMR8587, Université d’Evry-Val-d’Essonne, Laboratoire Analyse et Modélisation pour la Biologie et l’Environnement, F-91025 Evry (France)

2014-01-15

Graphical abstract: Atmospheric pressure photoIonization mass spectra of synthetic oligomers were recorded in the negative mode by varying the photon energy using synchrotron radiation. Photon energy required for an efficient ionization of the polymer was correlated to ionization potential of the solvent (for example 9.4 eV for tetrahydrofuran). -- Highlights: •Atmospheric pressure photoionization was performed using synchrotron radiation. •Photoionization of oligomers in THF with 10% CH{sub 2}Cl{sub 2} produces intact [M + Cl]{sup −} ions. •The photon energy required corresponds to ionization potential of the solvent. •Polymer distributions depend on source parameters such T °C and applied voltages. •Liquid chromatography was coupled to MS using an APPI interface for polymer analysis. -- Abstract: Atmospheric pressure photoionization (APPI) followed by mass spectrometric detection was used to ionize a variety of polymers: polyethylene glycol, polymethyl methacrylate, polystyrene, and polysiloxane. In most cases, whatever the polymer or the solvent used (dichloromethane, tetrahydrofuran, hexane, acetone or toluene), only negative ion mode produced intact ions such as chlorinated adducts, with no or few fragmentations, in contrast to the positive ion mode that frequently led to important in-source fragmentations. In addition, it was shown that optimal detection of polymer distributions require a fine tuning of other source parameters such as temperature and ion transfer voltage. Series of mass spectra were recorded in the negative mode, in various solvents (dichloromethane, tetrahydrofuran, hexane, toluene, and acetone), by varying the photon energy from 8 eV up to 10.6 eV using synchrotron radiation. To these solvents, addition of a classical APPI dopant (toluene or acetone) was not necessary. Courtesy of the synchrotron radiation, it was demonstrated that the photon energy required for an efficient ionization of the polymer was correlated to the

Preparation and biodistribution of radiolabeled fullerene C60 nanocrystals

International Nuclear Information System (INIS)

Nikolic, Nadezda; Vranjes-Duric, Sanja; Jankovic, Drina; Dokic, Divna; Mirkovic, Marija; Bibic, Natasa; Trajkovic, Vladimir

2009-01-01

The present study describes for the first time a procedure for the radiolabeling of fullerene (C 60 ) nanocrystals (nanoC 60 ) with Na 125 I, as well as the biodistribution of radiolabeled nanoC 60 ( 125 I-nanoC 60 ). The solvent exchange method with tetrahydrofuran was used to make colloidal water suspensions of radiolabeled nanoC 60 particles. The radiolabeling procedure with the addition of Na 125 I to tetrahydrofuran during dissolution of C 60 gave a higher radiochemical yield of radiolabeled nanoC 60 particles in comparison to the second option, in which Na 125 I was added after C 60 was dissolved. Using photon correlation spectroscopy and transmission electron microscopy, 125 I-nanoC 60 particles were found to have a crystalline structure and a mean diameter of 200-250 nm. The 125 I-nanoC 60 had a particularly high affinity for human serum albumin, displaying 95% binding efficiency after 1 h. Biodistribution studies of 125 I-nanoC 60 in rats indicated significant differences in tissue accumulation of 125 I-nanoC 60 and the radioactive tracer Na 125 I. The higher accumulation of radiolabeled nanoC 60 was observed in liver and spleen, while accumulation in thyroid, stomach, lungs and intestines was significantly lower in comparison to Na 125 I. In addition to being useful for testing the biological distribution of nanoC 60 , the described radiolabeling procedure might have possible applications in cancer radiotherapy.

Freezing polystyrene-b-poly(2-vinylpyridine) micelle nanoparticles with different nanostructures and sizes.

Science.gov (United States)

Fan, Hailong; Jin, Zhaoxia

2014-04-28

Herein we report how to control the nanostructures and sizes of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) nanoparticles via manipulating freezing in solvent-exchange. By characterizing and analyzing the distinct structural features of the obtained nanoparticles, we recognized that micelle self-assembly happens in the precipitation of PS-b-P2VP when water is added into the block copolymer (BCP) solution. Solvent properties significantly influence micelle types that are vesicles in acetone/H2O and spherical micelles in tetrahydrofuran/H2O, respectively, thus further inducing different frozen nanostructures of the obtained nanoparticles, onion-like in acetone/H2O and large compound micelles in tetrahydrofuran/H2O. By changing the concentration of the block copolymers and the Vsolvent/VH2O ratio to modify the freezing stage at which block copolymer micelles are frozen, we can further control the size of the nanoparticles. Moreover, small molecules (phosphotungstic acid, pyrene, 1-pyrenebutyric acid) can be trapped into the block copolymer nanoparticles via the freezing process. Their distribution in the nanoparticles relies not only on the solvent property, but also on their interactions with block copolymers. The hybrid nanoparticles with ordered distribution of small molecules can be further changed to partially-void nanoparticles. Our study demonstrated that manipulating the freezing of block copolymers in the solvent exchange process is a simple and controllable fabrication method to generate BCP nanoparticles with different architectures.

Solvent influence upon structure & throughput of poly vinyledene fluoride thin film nano-patterns by imprint lithography

Science.gov (United States)

Sankar, M. S. Ravi; Gangineni, R. B.

2018-04-01

This work aims at understanding the solvent influence upon the throughput and structure of poly vinyledene fluoride (PVDF)nano-patterned films. The PVDF thin films are deposited by spin coating method using Dimethylsulfoxide (DMSO), Tetrahydrofuran (THF) and 2-butanone solvents. The nano-patterns are realized by imprinting SONY 700 MB CD aluminum constructions on PVDF thin filmsusing imprint lithography technique under ambient annealing temperature and pressure. Surface morphology &imprint pattern transfer quality is evaluated with Atomic force microscopy (AFM). Raman spectroscopy is used for evaluating the structural evolutions with respect to solvent & patterning.

(3R,6R,12R,20S,24S-3,6,12-Triacetyl-20,24-epoxydammarane-3,6,12,25-tetraol

Directory of Open Access Journals (Sweden)

Qing-Guo Meng

2011-01-01

Full Text Available The title compound, C36H58O8, was prepared from 20(S-protopanaxatriol, which was degraded from Panax quinquefolium saponin with sodium in glycerine, extracted and seperated by flash chromatography. Three six-membered rings are in chair conformations, the five-membered ring is in an envelope form and the tetrahydrofuran ring has a conformation intermediate between half-chair and envelope. In the crystal, molecules are linked by O—H...O hydrogen bonds, and C—H...O contacts also occur. The absolute structure was assigned on the basis of the synthesis.

Determination of the hydrothermal degradation products of D-(U-14C) glucose and D-(U-14C) fructose by TLC

International Nuclear Information System (INIS)

Bonn, G.; Bobleter, O.

1983-01-01

Hydrothermal degradation was examined using D-(U- 14 C) glucose and D-(U- 14 C) fructose. By thin layer chromatography with methylene chloride, tetrahydrofuran (THF), acetic acid - 60:20:20 as a mobile phase; it was possible to separate and identify the carbohydrates and their reaction products, glyceraldehyde, dihydroxyacetone, methylglyoxal, glycolaldehyde, 5-hydroxymethylfurfural and furfural. Up to 99% of the initial activity was determined by scintillation counting of the TL-chromatograms. A reaction scheme for the hydrothermal degradation of glucose and fructose was obtained from these results. (author)

Acceleration of Anti-Markovnikov Hydroamination in the Synthesis of an Active Pharmaceutical Ingredient

DEFF Research Database (Denmark)

Mitic, Aleksandar; Skovby, Tommy; Dam-Johansen, Kim

2016-01-01

Slow chemical reactions are a big challenge in the modern pharmaceutical industry. Their accelerations together with the introduction of continuous manufacturing modes are major drivers for future development. One example reaction is hydroamination, a reaction between unsaturated hydrocarbons and...... with a huge excess of HEP and reaction times of up to 24h. Acceleration of the reaction from 24 down to 4h is achieved by switching from batch operation mode in toluene to either solvent-free batch mode or microwave-assisted hydroamination with tetrahydrofuran as a solvent....

Synthesis of carbon-14-labeled sodium palmoxirate and its coenzyme A ester

Energy Technology Data Exchange (ETDEWEB)

Weaner, L.E.; Hoerr, D.C.

1986-04-01

Synthetic procedures for the preparation of carbon-14-labeled sodium palmoxirate (TDGA), labeled either in the carboxyl position or in the tetradecyl hydrocarbon chain, are described. In addition, the synthesis of the coenzyme A ester of TDGA-14C with a specific activity of 51 mCi/mmol is reported. The coenzyme A ester was prepared by formation of the acyl chloride with oxalyl chloride followed by reaction with coenzyme A (CoA) in a borate-buffered tetrahydrofuran solution. Purification methods and analytical and stability data are reported for the compounds.

The use of deuterium n.m.r. spectroscopy in mechanistic studies of exchange reactions of ethers on supported metal catalysts

International Nuclear Information System (INIS)

Campbell, J.A.; Kemball, Charles; McDougall, G.S.

1987-01-01

Exchange reactions of diethyl ether (DEE) and tetrahydrofuran (THF) with deuterium have been studied over supported nickel, palladium, platinum, and rhodium catalysts. Products from most of the systems were analysed by deuterium n.m.r. spectroscopy (55.28 MHz) which gave quantitative results about the distribution of deuterium in the exchanged ethers. The results confirm earlier conclusions about the mechanism of the exchange of DEE and provide new evidence about the reactions of THF. Some hydrogenolysis occurred simultaneously with exchange of THF over both nickel and platinum. (author)

Enantioselective Copper-Catalyzed Carboetherification of Unactivated Alkenes**

Science.gov (United States)

Bovino, Michael T.; Liwosz, Timothy W.; Kendel, Nicole E.; Miller, Yan; Tyminska, Nina

2014-01-01

Chiral saturated oxygen heterocycles are important components of bioactive compounds. Cyclization of alcohols onto pendant alkenes is a direct route to their synthesis, but few catalytic enantioselective methods enabling cyclization onto unactivated alkenes exist. Herein is reported a highly efficient copper-catalyzed cyclization of γ-unsaturated pentenols that terminates in C-C bond formation, a net alkene carboetherification. Both intra- and intermolecular C-C bond formations are demonstrated, yielding functionalized chiral tetrahydrofurans as well as fused-ring and bridged-ring oxabicyclic products. Transition state calculations support a cis-oxycupration stereochemistry-determining step. PMID:24798697

Formation and pore structure of boron nitride aerogels

International Nuclear Information System (INIS)

Lindquist, D.H.; Borek, T.T.; Kramer, S.J.; Kramer, S.J.; Naruta, C.K.; Johnson, G.; Schaeffer, R.; Smith, D.M.; Paine, R.T.

1990-01-01

This paper reports gels containing a poly(borazinyl amine) and tetrahydrofuran processed by CO 2 supercritical drying techniques followed by pyrolysis. The resulting BN ceramic aerogels are highly porous, and the microstructure, porosity, and surface area characteristics have been examined. The aerogels show excellent thermal stability exhibiting surface areas in excess of 350 m 2 /g and porosities greater than 0.8 even when heated in argon at 1500 degrees C for 8 h. By removing solvent via evaporation before supercritical drying, the mean pore radius can be varied between 3.6 and 10 nm

Watching the Solvation of Atoms in Liquids One Solvent Molecule at a Time

Science.gov (United States)

Bragg, Arthur E.; Glover, William J.; Schwartz, Benjamin J.

2010-06-01

We use mixed quantum-classical molecular dynamics simulations and ultrafast transient hole-burning spectroscopy to build a molecular-level picture of the motions of solvent molecules around Na atoms in liquid tetrahydrofuran. We find that even at room temperature, the solvation of Na atoms occurs in discrete steps, with the number of solvent molecules nearest the atom changing one at a time. This explains why the rate of solvent relaxation differs for different initial nonequilibrium states, and reveals how the solvent helps determine the identity of atomic species in liquids.

A divergent synthesis of the delta(13)-9-isofurans.

Science.gov (United States)

Taber, Douglass F; Gu, Peiming; Li, Rui

2009-08-07

A stereodivergent total synthesis of the Delta(13)-9-isofurans has been developed. The four core substituted tetrahydrofurans were prepared by the Sharpless asymmetric epoxidation and Sharpless asymmetric dihydroxylation followed by cascade cyclization. The relative configuration at C-8 was inverted by oxidation followed by immediate L-Selectride reduction. The relative configuration of the C-15 diastereomers was assigned by (S)-Binol/LAH/EtOH reduction of the corresponding enone. This synthesis of the Delta(13)-9-isofurans will provide sufficient material for further investigation of their biological activity.

A Divergent Synthesis of the Δ13-9-Isofurans

Science.gov (United States)

Taber, Douglass F.; Gu, Peiming; Li, Rui

2009-01-01

A stereodivergent total synthesis of the Δ13-9-isofurans has been developed. The four core substituted tetrahydrofurans were prepared by the Sharpless asymmetric epoxidation and Sharpless asymmetric dihydroxylation followed by cascade cyclization. The relative configuration at C-8 was inverted by oxidation followed by immediate L-selectride reduction. The relative configuration of the C-15 diastereomers were assigned by (S)-Binol/LAH/EtOH reduction of the corresponding enone. This synthesis of the Δ13-9-isofurans will provide sufficient material for further investigation of their biological activity. PMID:19572754

The direct oxidative diene cyclization and related reactions in natural product synthesis

Directory of Open Access Journals (Sweden)

Juliane Adrian

2016-09-01

Full Text Available The direct oxidative cyclization of 1,5-dienes is a valuable synthetic method for the (diastereoselective preparation of substituted tetrahydrofurans. Closely related reactions start from 5,6-dihydroxy or 5-hydroxyalkenes to generate similar products in a mechanistically analogous manner. After a brief overview on the history of this group of transformations and a survey on mechanistic and stereochemical aspects, this review article provides a summary on applications in natural product synthesis. Moreover, current limitations and future directions in this area of chemistry are discussed.

CCDC 887968: Experimental Crystal Structure Determination : Dichloro-bis(tricyclohexylphosphine)-(3-phenylindenylidene)-ruthenium tetrahydrofuran solvate

KAUST Repository

Urbina-Blanco, C.A.

2014-01-01

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An experimental and theoretical kinetic study of the reaction of OH radicals with tetrahydrofuran

KAUST Repository

Giri, Binod; Khaled, Fathi; Szőri, Milá n; Viskolcz, Bé la; Farooq, Aamir

2016-01-01

by the rapid thermal decomposition of tert-butyl hydroperoxide, and a UV laser absorption technique was used to monitor the mole fraction of OH radicals. High-level CCSD(T)/cc-pV(D,T)Z//MP2/aug-cc-pVDZ quantum chemical calculations were performed to explore

Formation of itraconazole-succinic acid cocrystals by gas antisolvent cocrystallization.

Science.gov (United States)

Ober, Courtney A; Gupta, Ram B

2012-12-01

Cocrystals of itraconazole, an antifungal drug with poor bioavailability, and succinic acid, a water-soluble dicarboxylic acid, were formed by gas antisolvent (GAS) cocrystallization using pressurized CO(2) to improve itraconazole dissolution. In this study, itraconazole and succinic acid were simultaneously dissolved in a liquid solvent, tetrahydrofuran, at ambient conditions. The solution was then pressurized with CO(2), which decreased the solvating power of tetrahydrofuran and caused crystallization of itraconazole-succinic acid cocrystals. The cocrystals prepared by GAS cocrystallization were compared to those produced using a traditional liquid antisolvent, n-heptane, for crystallinity, chemical structure, thermal behavior, size and surface morphology, potential clinical relevance, and stability. Powder X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy analyses showed that itraconazole-succinic acid cocrystals with physical and chemical properties similar to cocrystals produced using a traditional liquid antisolvent technique can be prepared by CO(2) antisolvent cocrystallization. The dissolution profile of itraconazole was significantly enhanced through GAS cocrystallization with succinic acid, achieving over 90% dissolution in less than 2 h. The cocrystals appeared stable against thermal stress for up to 4 weeks under accelerated stability conditions, showing only moderate decreases in their degree of crystallinity but no change in their crystalline structure. This study shows the utility of an itraconazole-succinic acid cocrystal for improving itraconazole bioavailability while also demonstrating the potential for CO(2) to replace traditional liquid antisolvents in cocrystal preparation, thus making cocrystal production more environmentally benign and scale-up more feasible.

Structural features of an exocyclic adduct positioned opposite an abasic site in a DNA duplex

International Nuclear Information System (INIS)

Kouchakdjian, M.; Patel, D.J.; Eisenberg, M.; Johnson, F.; Grollman, A.P.

1991-01-01

Structural studies have been extended to dual lesions where an exocyclic adduct is positioned opposite an abasic site in the center of a DNA oligomer duplex. NMR and energy minimization studies were performed on the 1,N 2 -propanodeoxyguanosine exocyclic adduct (X) positioned opposite a tetrahydrofuran abasic site (F) with the dual lesions located in the center of the (C1-A2-T3-G4-X5-G6-T7-A8-C9)·(G10-T11-A12-C13-F14-C15-A16-T17-G18) X·F 9-mer duplex. Two-dimensional NMR experiments establish that the X·F 9-mer helix is right-handed with Watson-Crick A·T and G·C base pairing on either side of the lesion site. NOEs are detected from the methylene protons of the exocyclic ring of X5 to the imino protons of G4·C15 and G6·C13 which flank the lesion site, as well as to the H1' and H1 double-prime protons of the cross strand F14 tetrahydrofuran moiety. These NMR results establish that the exocyclic adduct X5 is positioned between flanking G4·C15 and G6·C13 base pairs and directed toward the abasic lesion F14 on the partner strand. These studies establish that the exocyclic ring of the 1,N 2 -propanodeoxyguanosine adduct fits into the cavity generated by the abasic site

Regulated bioanalysis of conformers - A case study with ASP2151 in dog plasma and urine.

Science.gov (United States)

Ohtsu, Yoshiaki; Otsuka, Shohei; Nakamura, Takeshi; Noguchi, Kiyoshi

2015-08-01

We developed and validated bioanalytical methods for a potent helicase-primase inhibitor ASP2151 that has two conformers. These conformers elute as unseparated broad peaks under ordinary high-performance liquid chromatographic conditions, indicating discernable differences in hydrophobicity. We observed that column temperature and mobile phase pH have no effect on these peaks and that conformers form a single symmetrical peak when tetrahydrofuran is added to the mobile phase. In addition, we needed to develop semi-automated methods where inter-conversion of the conformers is unlikely to cause sample-to-sample extraction variability. Briefly, following the addition of deuterium-labeled ASP2151 as an internal standard (IS), dog plasma samples or acetonitrile-added urine samples were filtrated. The filtrates were then injected into a column-switching liquid chromatography-tandem mass spectrometry (LC-MS/MS) system and trapped onto an extraction column. Extracts were back-flushed onto an analytical C18 column (4.6×50mm, 3μm) with a mobile phase consisting of methanol, tetrahydrofuran, and 20mmol/L ammonium acetate (45:5:50, v/v/v). The eluent was monitored in the negative atmospheric pressure chemical ionization mode. The calibration curve was linear over a range of 5-1000ng/mL for plasma and 0.5-100μg/mL for urine. Validation data met the acceptance criteria in accordance with regulatory guidance and demonstrated that these methods were selective, accurate, and reproducible. In addition, the present methods were successfully applied to a pharmacokinetic study in dogs. Copyright © 2015 Elsevier B.V. All rights reserved.

Liquid chromatographic-tandem mass spectrometric method for the simultaneous determination of alkylphenols polyethoxylates, alkylphenoxy carboxylates and alkylphenols in wastewater and surface-water.

Science.gov (United States)

Ciofi, L; Ancillotti, C; Chiuminatto, U; Fibbi, D; Checchini, L; Orlandini, S; Del Bubba, M

2014-10-03

Four different pellicular stationary phases (i.e. octadecylsilane, octasilane, Phenyl-Hexyl and pentafluorophenyl) were investigated for the chromatographic resolution of alkylphenols (APs), alkylphenols polyethoxylates (APnEOs) and alkylphenoxy carboxylates (APECs) using mixtures of water and organic solvents (i.e. methanol, acetonitrile and tetrahydrofuran) as eluents, in order to obtain their determination by a single LC-MS/MS run. In fact, alkylphenols and alkylphenoxy carboxylates must be analysed in negative ion mode, whereas alkylphenols polyethoxylates undergo ionisation only in positive ion mode, and therefore, two distinct LC-MS/MS analysis are commonly adopted. The best resolution among the aforementioned target analytes was achieved on the pentafluorophenyl column, eluting with an acidified water-acetonitrile-tetrahydrofuran mixture and using the post column addition of an ammonia solution in methanol for the detection of positively ionisable compounds. Under these optimized chromatographic conditions the investigated compounds were determined via a single chromatographic run, with only one polarity switch, in 15min, achieving the following instrumental detection limits: 600pg for AP1EOs, 0.8-14pg for AP2EOs, 10.4-150pg for APs and 4.4-4.8pg for APECs. The chromatographic method was coupled with solid-phase extraction and clean-up procedures and successfully applied to the analysis of wastewater and surface water samples, highlighting mean concentration ranging from 6ng/L for 4-t-OP1EC to 1434ng/L for 4-NP1121EC, depending on the sample analysed. Copyright © 2014 Elsevier B.V. All rights reserved.

8a-Methyl-5,6,8,8a,9,10-hexahydro-10,12a-epoxyisoindolo[1,2-a]isoquinolinium iodide

Directory of Open Access Journals (Sweden)

Flavien A. A. Toze

2010-06-01

Full Text Available The title compound, C17H18NO+·I−, is an adduct resulting from an intramolecular Diels–Alder reaction of methallyl chloride with 3,4-dihydro-1-furylisoquinoline. The cation comprises a fused pentacyclic system containing three five-membered rings (dihydropyrrole, dihydrofuran and tetrahydrofuran and two six-membered rings (tetrahydropyridine and benzene. The five-membered rings have the usual envelope conformations, and the central six-membered tetrahydropyridine ring adopts the unsymmetrical half-boat conformation. In the crystal, cations and iodide anions are bound by weak intermolecular hydrogen-bonding interactions into a three-dimensional framework.

Palladium-catalysed cyclisation of alkenols: Synthesis of oxaheterocycles as core intermediates of natural compounds

Directory of Open Access Journals (Sweden)

Miroslav Palík

2014-09-01

Full Text Available The study of Pd-catalysed cyclisation reactions of alkenols using different catalytic systems is reported. These transformations affect the stereoselective construction of mono- and/or bicyclic oxaheterocyclic derivatives depending on a starting alkenol. The substrate scope and proposed mechanism of Pd-catalysed cyclisation reactions are also discussed. Moreover, the diastereoselective Pd-catalysed cyclisation of appropriate alkenols to tetrahydrofurans and subsequent cyclisation provided properly substituted 2,5-dioxabicyclo[2.2.1]heptane and 2,6-dioxabicyclo[3.2.1]octane, respectively. Such bicyclic ring subunits are found in many natural products including ocellenynes and aurovertines.

Pyrimidine and nucleoside gamma-esters of L-Glu-Sar

DEFF Research Database (Denmark)

Eriksson, André H; Elm, Peter L; Begtrup, Mikael

2005-01-01

-tetrahydrofuran-3-yl ester)-Sar (I), l-Glu(thymine-1-yl-methyl ester)-Sar (II) and l-Glu(acyclothymidine)-Sar (III) were synthesised and in vitro stability was studied in various aqueous and biological media. Affinity to and translocation via hPEPT1 was investigated in mature Caco-2 cell monolayers, grown......The aim of the present study was to improve the synthetic pathway of bioreversible dipeptide derivatives as well as evaluate the potential of using l-Glu-Sar as a pro-moiety for delivering three newly synthesised nucleoside and pyrimidine l-Glu-Sar derivatives. l-Glu(trans-2-thymine-1-yl...

One-step catalytic conversion of biomass-derived carbohydrates to liquid fuels

Science.gov (United States)

Sen, Ayusman; Yang, Weiran

2014-03-18

The invention relates to a method for manufacture of hydrocarbon fuels and oxygenated hydrocarbon fuels such as alkyl substituted tetrahydrofurans such as 2,5-dimethyltetrahydrofuran, 2-methyltetrahydrofuran, 5-methylfurfural and mixtures thereof. The method generally entails forming a mixture of reactants that includes carbonaceous material, water, a metal catalyst and an acid reacting that mixture in the presence of hydrogen. The reaction is performed at a temperature and for a time sufficient to produce a furan type hydrocarbon fuel. The process may be adapted to provide continuous manufacture of hydrocarbon fuels such as a furan type fuel.

Synthesis of samarium, europium and ytterbium acetylenides

International Nuclear Information System (INIS)

Bochkarev, M.N.; Fedorova, E.A.; Glushkova, N.V.; Protchenko, A.V.; Druzhkov , O.N.; Khorshev, S.Ya.

1995-01-01

Ethynyl complexes of samarium, europium and ytterbium were prepared by interaction of naphthalinides of metals with acetylene in tetrahydrofuran. The compounds are isolated in the form of dark-coloured pyrophore powders. Data of magnetic measurements suggest that in the course of the reaction Sm(2) is oxidized completely to Sm(3), Yb(2) transforms into Yb(3) partially, whereas europium preserves its initial bivalent state. Hydrolysis of the compounds prepared provides acetylene, ethylene, ethane and hydrogen which indicates the presence of acethylenide Ln 2 C 2 and hydride LnH groupings (Ln = Sm, Eu, Yb). 9 refs., 2 tabs

Dry-column chromatography of uranium. Application to chemical analysis of monazite and phosphate rock for uranium

Energy Technology Data Exchange (ETDEWEB)

Oguma, K; Kuroda, R [Chiba Univ. (Japan). Faculty of Engineering

1981-08-01

A dry-column chromatographic technique has been applied to the separation of uranium from complicated matrices. It has been demonstrated that operating parameters of thin-layer chromatography on silanized silica gel in isopropyl ether - tetrahydrofuran - nitric acid (65:20:3) can be transferred to this technique. Chromatograms are thus easily developed on dry packed column with the solvent system of the type used in the TLC. Uranium is eluted off the column and determined with Arsenazo III spectrophotometrically. The technique is successfully applied to the determination of uranium in monazite and phosphate rock samples with good precision and accuracy.

Alisiaquinones and alisiaquinol, dual inhibitors of Plasmodium falciparum enzyme targets from a New Caledonian deep water sponge.

Science.gov (United States)

Desoubzdanne, Denis; Marcourt, Laurence; Raux, Roselyne; Chevalley, Séverine; Dorin, Dominique; Doerig, Christian; Valentin, Alexis; Ausseil, Frédéric; Debitus, Cécile

2008-07-01

Four new meroterpenes, alisiaquinones A-C (1-3) and alisiaquinol (4), were isolated from a New Caledonian deep water sponge. Their structures and relative stereochemistry were elucidated by spectroscopic data analysis. They are related to xestoquinone, but showed unusual substitution on a tetrahydrofuran junction. They displayed micromolar range activity on two enzymatic targets of importance for the control of malaria, the plasmodial kinase Pfnek-1 and a protein farnesyl transferase, as well as on different chloroquine-sensitive and -resistant strains of Plasmodium falciparum. Alisiaquinone C displayed a submicromolar activity on P. falciparum and a competitive selectivity index on the different plasmodial strains.

Preparation and characterization of aliphatic diphenyl esters intended as precursors for polyesters

DEFF Research Database (Denmark)

Hvilsted, S.; Andruzzi, F.; Cerrai, P.

1991-01-01

An extensive number of aliphatic diphenyl esters, C6H5OOC(CH2)nCOOC6H5 (n = O,...,8,10,11,12,14), have been prepared in pure form. The crystalline melting points these esters exhibit an odd-even temperature behaviour, with the higher-melting even series (n even) displaying a minimum for n = 8 while...... based on similar data from phenyl esters, interpreted as the results of an apparent macrocyclic conformation of the larger diphenyl esters. High-performance size exclusion chromatography (s.e.c.) of diphenyl esters, phenyl esters, aromatic and linear hydrocarbons in tetrahydrofuran, toluene...

Control the Morphologies and the Pore Architectures of Meso porous Silicas through a Dual-Templating Approach

International Nuclear Information System (INIS)

Wang, H.; Chen, H.; Xu, Z.; Wang, S.; Li, B.; Li, Y.

2012-01-01

Meso porous silica nanospheres were prepared using a chiral cationic low-molecular-weight amphiphile and organic solvents such as toluene, cyclohexane, and tetrachlorocarbon through a dual-templating approach. X-ray diffraction, nitrogen sorption, field emission scanning electron microscopy, and transmission electron microscopy techniques have been used to characterize the meso porous silicas. The volume ratio of toluene to water plays an important role in controlling the morphologies and the pore architectures of the meso porous silicas. It was also found that meso porous silica nano flakes can be prepared by adding tetrahydrofuran to the reaction mixtures.

Technical note: Simultaneous carotenoid and vitamin analysis of milk from total mixed ration-fed cows optimized for xanthophyll detection.

Science.gov (United States)

Stout, M A; Benoist, D M; Drake, M A

2018-06-01

Concentrations of retinol, α-tocopherol, and major carotenoids in dairy products are often determined simultaneously by liquid chromatography. These compounds have different polarity and solubility; thus, extracting them simultaneously can be difficult and inefficient. In milks with low carotenoid concentrations, the xanthophylls lutein and zeaxanthin may not be completely resolved using common extraction techniques. A simplified method was developed to optimize extraction efficiency and the limit of detection and limit of quantification (LoQ) of lutein and zeaxanthin in bovine milk without decreasing sensitivity to other vitamins or carotenoids. The developed method evaluates lutein, zeaxanthin, β-carotene, retinol, and α-tocopherol simultaneously by ultra-high performance liquid chromatography-photodiode array detection. Common saponification temperatures (40-60°C) and concentrations of KOH in water (10-50% KOH wt/vol) were evaluated. Multiple solvents were evaluated for optimal xanthophyll extraction (diethyl ether, dichloromethane, hexane, and tetrahydrofuran) following saponification. The limit of detection and LoQ were defined as 3:1 and 10:1 signal-to-noise ratio, respectively. All experiments were performed in triplicate. The optimal saponification procedure was a concentration of 25% KOH at either 40 or 50°C. Saponified extracts solubilized in solutions containing diethyl ether had greater concentrations of lutein- than hexane- or tetrahydrofuran-based solutions, with peak areas above LoQ values. The solution containing diethyl ether solubilized similar concentrations of retinol, α-tocopherol, and β-carotene when compared with other solutions. The proposed optimized method allows for the simultaneous determination of carotenoids from milk with increased lutein and zeaxanthin sensitivity without sacrificing recovery of retinol, α-tocopherol, and β-carotene. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights

Characterization of Catalytic Fast Pyrolysis Oils: The Importance of Solvent Selection for Analytical Method Development

Energy Technology Data Exchange (ETDEWEB)

Ferrell, Jack R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Ware, Anne E [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2018-02-25

Two catalytic fast pyrolysis (CFP) oils (bottom/heavy fraction) were analyzed in various solvents that are used in common analytical methods (nuclear magnetic resonance - NMR, gas chromatography - GC, gel permeation chromatography - GPC, thermogravimetric analysis - TGA) for oil characterization and speciation. A more accurate analysis of the CFP oils can be obtained by identification and exploitation of solvent miscibility characteristics. Acetone and tetrahydrofuran can be used to completely solubilize CFP oils for analysis by GC and tetrahydrofuran can be used for traditional organic GPC analysis of the oils. DMSO-d6 can be used to solubilize CFP oils for analysis by 13C NMR. The fractionation of oils into solvents that did not completely solubilize the whole oils showed that miscibility can be related to the oil properties. This allows for solvent selection based on physico-chemical properties of the oils. However, based on semi-quantitative comparisons of the GC chromatograms, the organic solvent fractionation schemes did not speciate the oils based on specific analyte type. On the other hand, chlorinated solvents did fractionate the oils based on analyte size to a certain degree. Unfortunately, like raw pyrolysis oil, the matrix of the CFP oils is complicated and is not amenable to simple liquid-liquid extraction (LLE) or solvent fractionation to separate the oils based on the chemical and/or physical properties of individual components. For reliable analyses, for each analytical method used, it is critical that the bio-oil sample is both completely soluble and also not likely to react with the chosen solvent. The adoption of the standardized solvent selection protocols presented here will allow for greater reproducibility of analysis across different users and facilities.

[Bis(TrimethylsilylMethyl]Lithium and -Sodium: Solubility in Alkanes and Complexes with O- and N- Donor Ligands

Directory of Open Access Journals (Sweden)

Markus von Pilgrim

2017-06-01

Full Text Available In contrast to alkyl compounds of lithium, which play an important role in organometallic chemistry, the corresponding heavier alkali metal compounds are less investigated. These compounds are mostly insoluble in inert solvents or undergo solvolysis in coordinating solvents due to their high reactivity. An exception from this typical behavior is demonstrated by bis(trimethylsilylmethylsodium. This study examines alkane solutions of bis(trimethylsilylmethyllithium and -sodium by NMR spectroscopic and cryoscopic methods. In addition, structural studies by X-ray crystallography of the corresponding compounds coordinated by O- and N- ligands (tetrahydrofuran and tetramethylethylenediamine present possible structural motifs of the uncoordinated compounds in solution.

Desenvolvimento e validação de método espectrofotométrico para determinação de corante à base de luteína adicionado em iogurte desnatado

Directory of Open Access Journals (Sweden)

Ana Augusta Odorissi Xavier

2012-01-01

Full Text Available A simple analytical method for extraction and quantification of lutein colorant added to yogurt was developed and validated. The method allowed complete extraction of carotenoids using tetrahydrofuran in vortex, followed by centrifugation, partition to diethyl ether/petroleum ether, and drying. The carotenoids dissolved in ethanol were quantified by UV-Vis spectrophotometry. This method showed linearity in the range tested (1.41-13.42 µg g-1, limits of detection and quantification of 0.42 and 1.28 µg g-1, respectively, low relative standard deviation (3.4% and recovery ranging from 95 to 103%. The method proved reliable for quantification of lutein added to yogurt.

Synthesis of core-fluorescent four-armed star and dicyclic 8-shaped poly(THF)s by electrostatic self-assembly and covalent fixation (ESA–CF) protocol

KAUST Repository

Fujiwara, Susumu; Yamamoto, Takuya; Tezuka, Yasuyuki; Habuchi, Satoshi

2013-01-01

A pair of four-armed star and dicyclic 8-shaped poly(tetrahydrofuran)s, poly(THF)s, possessing a perylene diimide group at the core position (Ia and Ib, respectively) were synthesized by means of an electrostatic self-assembly and covalent fixation (ESA–CF) protocol. Mono- and bifunctional poly(THF)s having N-phenylpiperidinium salt end groups accompanying a perylene diimide tetracarboxylate as a counteranion were prepared by the ion-exchange reaction, and the subsequent covalent conversion by reflux in toluene afforded the corresponding core-fluorescent four-armed star and dicyclic 8-shaped poly(THF)s, (Ia and Ib, respectively) for the use of single-molecule fluorescence microscopy measurements.

New hydride compounds of 1,4-diazabicyclo[2.2.2]octane and its dication with borine and tetrahydridoborate anion and products of their transformations

International Nuclear Information System (INIS)

Shevchenko, Yu.N.; Yashina, N.I.; Markova, O.Z.; Trachevskij, V.V.

1996-01-01

New compounds [dabcoH 2 ](BH 4 ) 2 , dabco(BH 3 ) 2 2H 2 , [dabco(BH 3 ) 2 H 2 ] n have been synthesized by means of interaction between dihydrochloride of 1,4-diazobicyclo[2.2.2] octane (dabco) and NaBH 4 in the medium of nonaqueous solvents (glyme, diglyme, tetrahydrofuran, dimethylsulfoxide) and identified by the methods of element analysis, conductometry, 1 H, 11 B, 14 N NMR, IR spectroscopy and thermal analysis. A mechanism is suggested and the conditions are defined for mutual transformations of the compounds studied. Their ability to bind reversibly molecular hydrogen has been revealed for the first time. 19 refs.; 3 figs.; 1 tab

Development of methodology for synthesis of (66alpha66-C)-labeled phenethylamine

Energy Technology Data Exchange (ETDEWEB)

Jay, M.; Chaney, J.E.; Digenis, G.A. (Kentucky Univ., Lexington (USA))

1981-05-01

A one solvent two-step procedure for the synthesis of (..cap alpha..-C)-labeled phenethylamine is described. The method employs crown ethers to aid in the solubilization of sodium cyanide in tetrahydrofuran (THF) for the formation of phenylacetonitrile from benzyl chloride. Reduction of phenylacetonitrile to phenethylamine was accomplished with borane using the same solvent. The overall yield of phenethylamine was 44.5% based on cyanide. The procedure is amenable to hot cell conditions for eventual (..cap alpha..-/sup 11/C)-labeling of phenethylamine. Dimethylsulfoxide (DMSO) was found to be a less desirable solvent for this reaction due to its participation in the Kornblum oxidation.

The synthesis of no-carrier-added [11C]urea from [11C]carbon dioxide and application to [11C]uracil synthesis

International Nuclear Information System (INIS)

Chakraborty, P.K.; Mangner, T.J.; Chugani, H.T.

1997-01-01

No-carrier-added [ 11 C]urea has been synthesized by bubbling cyclotron-produced [ 11 C]-carbon dioxide directly into a tetrahydrofuran solution of lithium bis(trimethylsilyl)amide, followed by hydrolysis of the C-11 labeled adduct with aqueous ammonium chloride. Using this simple, one-pot method, [ 11 C]urea was produced in 55-70% radiochemical yield (decay-corrected) in 16 min following end-of-bombardment (or in 10 min following the introduction of the [ 11 C]carbon dioxide. The [ 11 C]urea thus produced was converted to [ 11 C]uracil (carrier-added) in 40-75% decay-corrected radiochemical yield by condensation with diethyl malate in presence of fuming sulfuric acid. (author)

Hydrocracking mechanisms in molten zinc chloride. Isotope scrambling and pyrolysis studies

International Nuclear Information System (INIS)

Larsen, J.W.; Earnest, S.

1979-01-01

Bruceton coal was hydrocracked in molten zinc chloride using H 2 -D 2 mixtures. No H-D was observed. The pyrolysis of Bruceton coal and a lignite in molten zinc chloride and an inert salt was carried out and the tetrahydrofuran and pyridine extractability of the products determined. In the absence of H 2 , zinc chloride is not an effective cracking catalyst. It is tentatively concluded that the catalytically active species is formed from zinc chloride and something in the coal and H 2 . The interactions between zinc chloride and the lignite appear to be significantly different than the interactions between zinc chloride and the bituminous coal. (Auth.)

Enantioselective copper-catalyzed carboetherification of unactivated alkenes.

Science.gov (United States)

Bovino, Michael T; Liwosz, Timothy W; Kendel, Nicole E; Miller, Yan; Tyminska, Nina; Zurek, Eva; Chemler, Sherry R

2014-06-16

Chiral saturated oxygen heterocycles are important components of bioactive compounds. Cyclization of alcohols onto pendant alkenes is a direct route to their synthesis, but few catalytic enantioselective methods enabling cyclization onto unactivated alkenes exist. Herein reported is a highly efficient copper-catalyzed cyclization of γ-unsaturated pentenols which terminates in C-C bond formation, a net alkene carboetherification. Both intra- and intermolecular C-C bond formations are demonstrated, thus yielding functionalized chiral tetrahydrofurans as well as fused-ring and bridged-ring oxabicyclic products. Transition-state calculations support a cis-oxycupration stereochemistry-determining step. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A hybrid lithium oxalate-phosphinate salt.

Science.gov (United States)

Shaffer, Andrew R; Deligonul, Nihal; Scherson, Daniel A; Protasiewicz, John D

2010-12-06

The novel organophosphorus-containing lithium salt Li(THF)[(C(2)O(4))B(O(2)PPh(2))(2)] (1; THF = tetrahydrofuran) was synthesized and characterized using a variety of spectroscopic techniques. An X-ray structural analysis on crystals of 1 grown from THF reveals a dimeric structure [Li(THF)(C(2)O(4))B(O(2)PPh(2))(2)](2)·THF, whereby the two units of 1 are bridged via P-O···Li interactions. Compound 1 displays high air and water stability and is also thermally robust, properties needed of electrolytes for their possible use as electrolytes and/or additives in lithium-ion battery applications.

Synthesis and characterization of near-IR absorbing metal-free and zinc(II phthalocyanines modified with aromatic azo groups

Directory of Open Access Journals (Sweden)

Mukaddes Özçeşmeci

2015-05-01

Full Text Available Metal-free and zinc(II phthalocyanine complexes bearing peripheral (E-4-((2-hydroxynaphthalen-1-yldiazenyl units have been synthesized. Novel phthalonitrile derivative required for the preparation of phthalocyanine complexes was prepared by coupling 4-aminophthalonitrile and 2-naphthol. The structures of these new compounds were characterized by using elemental analyses, proton nuclear magnetic resonance, fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, fluorescence spectroscopy and mass spectrometry. In the UV-Vis spectra a broad absorption band appears for phthalocyanine complexes at around 450–500 nm resulting from azo-group introduced onto the phthalocyanine ring. The photophysical properties of metal-free and zinc(II phthalocyanines were studied in tetrahydrofuran.

Interfacial charge trapping in the polymer solar cells and its elimination by solvent annealing

Directory of Open Access Journals (Sweden)

A. K. Chauhan

2016-09-01

Full Text Available The PCDTBT:PCBM solar cells were fabricated adopting a tandem layer approach to investigate the critical issues of charge trapping, radiation absorption, and efficiency in polymer solar cells. This layered structure was found to be a source of charge trapping which was identified and confirmed by impedance spectroscopy. The low efficiency in multilayered structures was related to trapping of photo-generated carriers and low carrier mobility, and thus an increased recombination. Solvent annealing of the structures in tetrahydrofuran vapors was found beneficial in homogenizing the active layer, dissolving additional interfaces, and elimination of charge traps which improved the carrier mobilities and eventually the device efficiencies.

Method to convert biomass to 5-(hydroxymethyl)-furfural (HMF) and furfural using lactones, furans, and pyrans as solvents

Science.gov (United States)

Dumesic, James A.; Ribeiro Gallo, Jean Marcel; Alonso, David

2014-07-08

Described is a process to produce hydroxymethyl furfural (HMF) from biomass-derived sugars. The process includes the steps of reacting a C5 and/or C6 sugar-containing reactant derived from biomass in a monophasic or biphasic reaction solution comprising water and a co-solvent. The co-solvent can be beta-, gamma-, and/or delta-lactones derived from biomass, tetrahydrofuran (THF) derived from biomass, and/or methyltetrahydrofuran (MTHF) derived from biomass. The reaction takes place in the presence of an acid catalyst and a dehydration catalyst for a time and under conditions such that at least a portion of glucose or fructose present in the reactant is converted to HMF.

Thin-layer chromatography - liquid chromatography, an ideal supplement demonstrated by the separation of lanthanoids

International Nuclear Information System (INIS)

Specker, H.; Hufnagel, A.

1984-01-01

All lanthanoids have been separated by thin-layer chromatography (TLC) with short retention times by using a mixture of ether/tetrahydrofurane (THF)/bis-(2-ethylhexyl)-phosphate (HDEHP)/nitric acid. The eluent was empirically tested by synergistic effects. The results have been transferred to high-performance liquid chromatography /HPLC). It was possible to use the same eluent in TLC and HPLC both for the analytical separation of all lanthanoids and for the separation of fission products. The experimental experience gained in HPLC could be applied to the pre-concentration of isotopes in TLC. Both methods excellently supplemented each other in the separation of lanthanoids. (orig.) [de

Reaction between chloromercurocobaltcarborane and undecaborate anion derivatives

International Nuclear Information System (INIS)

Lobanova, I.A.; Khitrova, O.M.; Petrovskij, P.V.; Bregadze, V.I.

2004-01-01

Interaction of Cs + C 2 B 9 H 12 - and exo-nido-5,6,10-[Cl(Ph 3 P) 2 RU]-5,6,10-(μ-H) 3 -10-H-7,8-C 2 B 9 H 8 with 9-chloromercurocobaltcarborane derivative - 3-(η 5 -Cp)-9-ClHg-3,1,2-CoC 2 B 9 H 10 (η 5 -Cp = cyclopentadiene) in mixed solvent tetrahydrofuran-water-ethanol at room temperature was studied using the methods of elementary analysis and 1 H, 31 P, 11 B NMR. Asymmetric metallocarborane cluster, in which exo-nido-ruthenacarborane and closo-cobalt- or dicarbo-nido-undecaborate fragments are bound via mercury atom, were prepared [ru

Synthesis of praseodymium allyl iodide complex and its use in piperilene polymerization

International Nuclear Information System (INIS)

Gajlyunas, G.A.; Biktimirov, R.Kh.; Khajrullina, R.M.; Marina, N.G.; Manakov, Yu.B.; Tolstikov, G.A.

1987-01-01

Synthesis, structure and catalytic properties of tetrahydrofuran praseodymium allyl iodine complex (1) are described and studied. Complex 1 is formed during interaction of allyl iodine with metal praseodymium (the molar ratio is 2:1) in THF at room temperature with 97% yield. It represents the solid powder-like substance of the light-brown colour with a pale green shade, being sensitive to moisture and oxygen and decomposing at temperature >120 deg. On the basis of the IR-spectroscopy data the supposition about the dimeric (or n-dimensional) complex structure is made. The complex prepared in combination with tributyl aluminium during piperylene polymerization gives a high-stereoregular and high-molecular polypiperylene

Synthesis of core-fluorescent four-armed star and dicyclic 8-shaped poly(THF)s by electrostatic self-assembly and covalent fixation (ESA–CF) protocol

KAUST Repository

Fujiwara, Susumu

2013-12-07

A pair of four-armed star and dicyclic 8-shaped poly(tetrahydrofuran)s, poly(THF)s, possessing a perylene diimide group at the core position (Ia and Ib, respectively) were synthesized by means of an electrostatic self-assembly and covalent fixation (ESA–CF) protocol. Mono- and bifunctional poly(THF)s having N-phenylpiperidinium salt end groups accompanying a perylene diimide tetracarboxylate as a counteranion were prepared by the ion-exchange reaction, and the subsequent covalent conversion by reflux in toluene afforded the corresponding core-fluorescent four-armed star and dicyclic 8-shaped poly(THF)s, (Ia and Ib, respectively) for the use of single-molecule fluorescence microscopy measurements.

On the origin of high transient anisotropies: An exemplification in a Cd-porphyrin

International Nuclear Information System (INIS)

Liang, Yu; Klinger, Melanie; Unterreiner, Andreas-Neil; Schalk, Oliver

2013-01-01

Transient anisotropy is a widely used spectroscopic method to access the polarization dynamics of a molecular sample. In this contribution, we present results on 5,10,15,20-tetraphenyl-porphyrinato cadmium (II) in tetrahydrofuran which exhibits values exceeding the typical range between 0.4 and −0.2 in dependence of the probe wavelength. These findings are explained by varying contributions from excited state absorption and ground state bleaching/stimulated emission. Model calculations show that time zero values and time decays are complex values that often do not correlate with the underlying physical processes. As a consequence, the interpretation of anisotropy experiments necessitates extreme care

Positronium formation in CS2 and C6F6 mixtures with triethylamine or tetrahydrofuran

International Nuclear Information System (INIS)

Zhicheng Zhang; Ito, Yasuo; Tabata, Yoneho

1990-01-01

Positronium (Ps) yields were measured for CS 2 /THF, CS 2 /TEA, C 6 F 6 THF and C 6 F 6 /TEA mixtures. Addition of C 6 F 6 or CS 2 into TEA or THF showed a similar influence which induces a decrease of Ps yield. This is ascribed to the non-dissociative electron scavenging by both CS 2 and C 6 F 6 . On the other hand, the effect of addition of TEA and THF has been found to be different for C 6 F 6 and CS 2 , i.e. both TEA and THF did not change Ps yield in CS 2 substantially, while they caused a sharp decrease of Ps yield in C 6 F 6 . The latter sharp decreases was ascribed to quenching of excited state of C 6 F 6 . This interpretation is supported by pulse radiolysis emission measurements for the same system, in which it was found that TEA quenches the excited state of C 6 F 6 efficiently. (author)

Synthetic oligomer analysis using atmospheric pressure photoionization mass spectrometry at different photon energies.

Science.gov (United States)

Desmazières, Bernard; Legros, Véronique; Giuliani, Alexandre; Buchmann, William

2014-01-15

Atmospheric pressure photoionization (APPI) followed by mass spectrometric detection was used to ionize a variety of polymers: polyethylene glycol, polymethyl methacrylate, polystyrene, and polysiloxane. In most cases, whatever the polymer or the solvent used (dichloromethane, tetrahydrofuran, hexane, acetone or toluene), only negative ion mode produced intact ions such as chlorinated adducts, with no or few fragmentations, in contrast to the positive ion mode that frequently led to important in-source fragmentations. In addition, it was shown that optimal detection of polymer distributions require a fine tuning of other source parameters such as temperature and ion transfer voltage. Series of mass spectra were recorded in the negative mode, in various solvents (dichloromethane, tetrahydrofuran, hexane, toluene, and acetone), by varying the photon energy from 8eV up to 10.6eV using synchrotron radiation. To these solvents, addition of a classical APPI dopant (toluene or acetone) was not necessary. Courtesy of the synchrotron radiation, it was demonstrated that the photon energy required for an efficient ionization of the polymer was correlated to the ionization energy of the solvent. As commercial APPI sources typically use krypton lamps with energy fixed at 10eV and 10.6eV, the study of the ionization of polymers over a wavelength range allowed to confirm and refine the previously proposed ionization mechanisms. Moreover, the APPI source can efficiently be used as an interface between size exclusion chromatography or reverse phase liquid chromatography and MS for the study of synthetic oligomers. However, the photoionization at fixed wavelength of polymer standards with different molecular weights showed that it was difficult to obtain intact ionized oligomers with molecular weights above a few thousands. Copyright © 2013 Elsevier B.V. All rights reserved.

Preparation and photoelectronic and electrochemical properties of oligo [(1,1-diisopropyl-3,4-diphenyl-2,5-silolene)-co-(alkylphenylsilylene)]s

Energy Technology Data Exchange (ETDEWEB)

Jung, Young Min; Park, Young Tae [Dept. of Chemistry, Keimyung University, Daegu (Korea, Republic of); Baek, Seong Ho [Div. of Green Energy Research, Daegu Gyeongbuk Institute of Science and Technology, Daegu (Korea, Republic of)

2017-01-15

We oligomerized 2,5-dibromo-1,1-diisopropyl-3,4-diphenyl-2,5-silole with dichloroalkylphenylsilanes utilizing n-BuLi to yield conjugated oligo [(1,1-diisopropyl-3,4-diphenyl-2,5-silolene)-co-(alkylphenylsilylene)]s. Gel permeation chromatography measurements confirm that the synthesized materials are oligomeric. In addition, the prepared oligomers show characteristic diene stretching bands at 1579–1599 cm{sup −1} in their FT-IR spectra. Furthermore, the oligomers are highly soluble in common organic solvents such as tetrahydrofuran and chloroform. In tetrahydrofuran, the oligomers show strong maximum electronic absorption bands at 253–292 nm with molar absorptivities of 1.61 × 10{sup 2} to 2.57 × 10{sup 4} /cm M in their UV–vis electronic absorption spectra, indicating that the maxima are red-shifted by 5–8 nm compared to the 2,5-dibromo-1,1-diisopropyl-3,4-diphenyl-2,5-silole monomer, strong maximum electronic excitation bands at 292–312 nm, and strong maxima electronic emission bands at 385–396 nm in the emission fluorescence spectra. The emission and absorption spectra strongly suggest that the prepared silole-containing oligomers may be conjugated through the oligomer backbone. In particular, cyclic voltammetry measurements of oligo[(1,1-diisopropyl-3,4-diphenyl-2,5-silolene)-co-(diphenylsilylene)] deposited on a glassy carbon electrode in 1.0 M aqueous hydrogen chloride show two oxidation potentials at 0.98 and 1.61 V vs. Ag/Ag{sup +}, and two reduction potentials at 0.00 and −1.93 V vs. Ag/Ag{sup +}. The oligomers were stable on heating to 200 °C under nitrogen, as determined by thermogravimetric analysis, losing between 4% and 23% of their starting weights.

Raman spectral and electrochemical studies of lithium/electrolyte interfaces

Energy Technology Data Exchange (ETDEWEB)

Odziemkowski, M

1922-01-01

Cyclic voltammetry, corrosion potential-time transients and Normal Raman spectroscopy have been employed to characterize the lithium-lithium salt, organic solvent, interfacial region. An in-situ cutting technique was developed to expose lithium metal. In-situ optical and ex-situ scanning electron microscopy (SEM) have been used to examine the morphology of the lithium electrode surface during exposure at open circuit and after anodic polarization. The main reaction product detected by in-situ Raman spectroscopy in the system/lithium/LiAsF[sub 6], tetrahydrofuran (THF) electrolyte was polytetrahydrofuran (PTHF). The conditions for the polymerization reaction in the presence of lithium metal have been determined. Tetrahydrofuran (THF) decomposition reaction mechanisms are discussed. Decomposition reaction products have been determined as arsenic (II) oxide, As[sub 2]O[sub 3] (arsenolite) and arsenious oxyfluoride AsF[sub 2]-O-AsF[sub 2]. Potentiodynamic polarization measurements revealed a substantial shift of the corrosion potential towards positive values and only a moderate increase of anodic dissolution current for in-situ cut lithium metal. Corrosion potential-time merits have been measured. The following electrolytes have been investigated: LiAsF[sub 6], LiPF[sub 6], LiClO[sub 4], and Li(CF[sub 3]SO[sub 2])[sub 2]N in THF, 2Me-THF, and propylene carbonate (PC). The transients permit the ranking of the reactivity of the electrolytes. These measurements have shed light on understanding the stability of various stability and and solvents in contact with lithium. Compared to purified electrolytes, small amounts of water shift the corrosion potential towards even more positive values. Intensive anodic cycling of a Li electrode in unpurified LiAsF[sub 6]/THF electrolyte leads to the breakdown of a surface film/films. While at the open circuit potential (OCP), water in this same electrolyte leads to crack formation in the bulk lithium electrode.

Freeze-substitution methods for Ni localization and quantitative analysis in Berkheya coddii leaves by means of PIXE

International Nuclear Information System (INIS)

Budka, D.; Mesjasz-PrzybyIowicz, J.; Tylko, G.; PrzybyIowicz, W.J.

2005-01-01

Leaves of Ni hyperaccumulator Berkheya coddii were chosen as a model to investigate the influence of eight freeze-substitution protocols on the Ni content and distribution. Freeze-substitution of leaf samples cryofixed by high-pressure freezing was carried out in dry acetone, methanol, diethyl ether and tetrahydrofuran. The same substitution media were also used with dimethylglyoxime added as a precipitation reagent. The samples were infiltrated and embedded in Spurr's resin. Micro-PIXE analysis of Ni concentration and localization, complemented by proton backscattering for matrix assessment, was performed using the nuclear microprobe at Materials Research Group, iThemba LABS, South Africa. True elemental maps and concentrations were obtained using GeoPIXE-II software. The results were compared with the control results obtained for the parallel air-dried samples, corrected for the water content. The highest Ni content was found in the leaf samples substituted in diethyl ether. This concentration was statistically different from the results obtained for other media. In case of diethyl ether medium Ni was mainly localized in the mesophyll tissue, and the distribution map of this element was in accordance with previous results obtained for freeze-dried and frozen-hydrated leaves of this species. The same distribution pattern was observed for specimens embedded in dry acetone, but Ni concentration was significantly lower. Tetrahydrofuran medium preserved Ni preferentially in the epidermis and vascular tissue, and the elemental map for samples embedded in this medium was distorted. Ni was almost completely washed out from samples substituted in methanol and it was thus impossible to obtain a picture of its distribution. Dimethylglyoxime did not improve the preservation of this element. These results show that diethyl ether is a suitable substitution medium for assessment of Ni concentration and distribution in leaves of B. coddii

Intramolecular, Exciplex-Mediated, Proton-Coupled, Charge-Transfer Processes in N,N-Dimethyl-3-(1-pyrenyl)propan-1-ammonium Cations: Influence of Anion, Solvent Polarity, and Temperature.

Science.gov (United States)

Safko, Trevor M; Faleiros, Marcelo M; Atvars, Teresa D Z; Weiss, Richard G

2016-06-16

An intramolecular exciplex-mediated, proton-coupled, charge-transfer (PCCT) process has been investigated for a series of N,N-dimethyl-3-(1-pyrenyl)propan-1-ammonium cations with different anions (PyS) in solvents of low to intermediate polarity over a wide temperature range. Solvent mediates both the equilibrium between conformations of the cation that place the pyrenyl and ammonium groups in proximity (conformation C) or far from each other (conformation O) and the ability of the ammonium group to transfer a proton adiabatically in the PyS excited singlet state. Thus, exciplex emission, concurrent with the PCCT process, was observed only in hydrogen-bond accepting solvents of relatively low polarity (tetrahydrofuran, ethyl acetate, and 1,4-dioxane) and not in dichloromethane. From the exciplex emission and other spectroscopic and thermodynamic data, the acidity of the ammonium group in conformation C of the excited singlet state of PyS (pKa*) has been estimated to be ca. -3.4 in tetrahydrofuran. The ratios between the intensities of emission from the exciplex and the locally excited state (IEx/ILE) appear to be much more dependent on the nature of the anion than are the rates of exciplex formation and decay, although the excited state data do not provide a quantitative measure of the anion effect on the C-O equilibrium. The activation energies associated with exciplex formation in THF are calculated to be 0.08 to 0.15 eV lower than for the neutral amine, N,N-dimethyl-3-(1-pyrenyl)propan-1-amine. Decay of the exciplexes formed from the deprotonation of PyS is hypothesized to occur through charge-recombination processes. To our knowledge, this is the first example in which photoacidity and intramolecular exciplex formation (i.e., a PCCT reaction) are coupled.

Activity coefficients at infinite dilution measurements for organic solutes and water in the ionic liquid 4-methyl-N-butyl-pyridinium bis(trifluoromethylsulfonyl)-imide

International Nuclear Information System (INIS)

Domanska, Urszula; Marciniak, Andrzej

2009-01-01

The activity coefficients at infinite dilution, γ 13 ∞ for 36 solutes: alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, thiophene, tetrahydrofuran, ethers, acetone, and water in the ionic liquid 4-methyl-N-butyl-pyridinium bis(trifluoromethylsulfonyl)-imide [bmPY][NTf 2 ] were determined by gas-liquid chromatography at temperatures from 298.15 K to 368.15 K. The partial molar excess enthalpies at infinite dilution values ΔH 1 E,∞ were calculated from the experimental γ 13 ∞ values obtained over the temperature range. The selectivity for different separation problems were calculated from the γ 13 ∞ and compared to the literature values for other ionic liquids, N-methyl-2-pyrrolidinone (NMP) and sulfolane.

Synthesis of [2-13C, 2-14C] 2-aminoethanol, [1-13C, 1-14C] 2-chloroethylamine, N,N'-bis([1-13C, 1-14C] 2-chloroethyl)-N-nitrosourea(BCNU) and N-([1-13C, 1-14C] 2-chloroethyl)-N-nitrosourea(CNU)

International Nuclear Information System (INIS)

Narayan, R.; Chang, C-j.

1982-01-01

[2- 13 C, 2- 14 C]2-Aminoethanol hydrochloride was prepared in good yield from Na*CN in a two step sequence by first converting the Na*CN to OHCH 2 *CN and then reducing the nitrile directly with a solution of borane-tetrahydrofuran complex. The reaction procedure was simple and the pure product could be obtained readily. Using this specifically labelled precursor, the synthesis of [1- 13 C, 1- 14 C]2-chloroethylamine hydrochloride, N-([1- 13 C, 1- 14 C]2-chloroethyl)-N-nitrosourea(CNU) and N,N'-bis([1- 13 C, 1- 14 C]2-chloroethyl)-N-nitrosourea(BCNU) in good yield without isotope scrambling was also reported. (author)

The formation of electronically excited fragments by the electron impact of furan and related five-membered heterocycles

International Nuclear Information System (INIS)

Tokue, Ikuo; Ikarashi, Masami; Takizawa, Sadachika; Ito, Yoshio

1983-01-01

In the wavelength region of 200-600 nm, photoemissions from electronically excited H, CH, C 2 , and CS (only from thiophene and tetrahydrothiophene) were observed when furan, tetrahydrofuran, thiophene, and tetrahydrothiophene were excited by electron impact (0-70 eV). Hydrogen atoms (n = 4) and CH(A 2 Δ) radicals were produced from these five-membered heterocycles via single collision excitations, while CS(A 1 PI) radicals from thiophene and tetrahydrothiophene were partly formed in secondary processes. The appearance potentials for the hydrogen Balmer β and the CH(A 2 Δ-X 2 PI) bands from these five-membered heterocycles are determined, and the dissociation processes forming H(n = 4) and CH(A) are discussed. (author)

Production and characterization of polymer nanocomposite with aligned single wall carbon nanotubes

International Nuclear Information System (INIS)

Chen Wei; Tao Xiaoming

2006-01-01

We reported a simple method to fabricate polymer nanocomposites with single-walled carbon nanotubes (SWNTs) having exceptional alignment and improved mechanical properties. The composite films were fabricated by casting a suspension of single walled carbon nanotubes in a solution of thermoplastic polyurethane and tetrahydrofuran. The orientation as well as dispersion of nanotubes was determined by scanning electron microscopy, transmission electron microscopy and polarized Raman spectroscopy. The macroscopic alignment probably results from solvent-polymer interaction induced orientation of soft segment chain during swelling and moisture curing. The tensile behavior of the aligned nanotube composite film was also studied. At a 0.5 wt.% nanotube loading, a 1.9-fold increase in Young's modulus was achieved

Direct transfer of graphene films for polyurethane substrate

Energy Technology Data Exchange (ETDEWEB)

Vilani, C.; Romani, E.C.; Larrudé, D.G. [Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, 22451-900 Rio de Janeiro, RJ (Brazil); Barbosa, Gelza M. [Diretoria de Sistemas de Armas da Marinha, Marinha do Brasil, 20010-00 Rio de Janeiro, RJ (Brazil); Freire, F.L., E-mail: lazaro@vdg.fis.puc-rio.br [Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, 22451-900 Rio de Janeiro, RJ (Brazil); Centro Brasileiro de Pesquisas Físicas, 22290-180 Rio de Janeiro, RJ (Brazil)

2015-11-30

Highlights: • Graphene was prepared by CVD using copper foils as substrates. • Monolayer, bilayer and multilayer graphene were transferred to PU. • Samples were characterized by Raman and optical spectroscopies. • PU/monolayer graphene has transmittance around 80% in visible range. - Abstract: We have proposed the direct transfer of large-area graphene films grown by chemical vapor deposition to polymeric substrate by evaporating of solvents of polyurethane/tetrahydrofurane solution. The graphene films on polyurethane substrates were characterized by Raman spectroscopy, optical and atomic force microscopies and UV–vis spectroscopy measurements. The Raman spectra revealed that it is possible to transfer in a controlled manner monolayer, bilayer and multilayer graphene films over polyurethane substrate.

Direct transfer of graphene films for polyurethane substrate

International Nuclear Information System (INIS)

Vilani, C.; Romani, E.C.; Larrudé, D.G.; Barbosa, Gelza M.; Freire, F.L.

2015-01-01

Highlights: • Graphene was prepared by CVD using copper foils as substrates. • Monolayer, bilayer and multilayer graphene were transferred to PU. • Samples were characterized by Raman and optical spectroscopies. • PU/monolayer graphene has transmittance around 80% in visible range. - Abstract: We have proposed the direct transfer of large-area graphene films grown by chemical vapor deposition to polymeric substrate by evaporating of solvents of polyurethane/tetrahydrofurane solution. The graphene films on polyurethane substrates were characterized by Raman spectroscopy, optical and atomic force microscopies and UV–vis spectroscopy measurements. The Raman spectra revealed that it is possible to transfer in a controlled manner monolayer, bilayer and multilayer graphene films over polyurethane substrate.

Terahertz Time Domain Spectroscopy for Structure-II Gas Hydrates

DEFF Research Database (Denmark)

Takeya, Kei; Zhang, Caihong; Kawayama, Iwao

2009-01-01

For the nondestructive inspection of gas hydrates, terahertz (THz) time-domain spectroscopy (TDS) was applied to tetrahydrofuran (THF) hydrate and propane hydrate. The absorption of propane hydrate monotonically increases with frequency, similar to the case of ice, while THF hydrate has...... a characteristic broad absorption peak at 0.5 THz corresponding to the dipole moment of THF molecules. The refractive indices of THF and propane hydrates are 1.725 and 1.775 at 1 THz, respectively, and show a slight but clear difference from the refractive index of ice (1.79). THz-TDS is a potentially useful...... technique for the ondestructive inspection of gas hydrates. # 2009 The Japan Society of Applied Physics...

A sample cell to study hydrate formation with x-ray scattering

International Nuclear Information System (INIS)

Conrad, Heiko; Lehmkuehler, Felix; Sternemann, Christian; Feroughi, Omid; Tolan, Metin; Simonelli, Laura; Huotari, Simo

2009-01-01

We present a new sample cell for measuring nonresonant inelastic x-ray scattering spectra of a tetrahydrofuran (THF)-water liquid mixture and THF hydrate. The hydrate is formed inside the cell after nucleation seeds have been offered by a special magnetic stirring mechanism. Hydrate formation was verified by wide angle x-ray scattering and nonresonant x-ray Raman scattering spectra at the oxygen K-edge. A broad range of scattering angles can be studied with this cell which is necessary for momentum transfer dependent inelastic x-ray scattering. This cell is ideal to examine other liquid hydrate formers or other liquid samples, which have to be mixed in situ during the measurements.

New MOF based on lithium tetrahydrofuran-2,3,4,5-tetracarboxylate: Its structure and conductivity behavior

Czech Academy of Sciences Publication Activity Database

Zima, Vítězslav; Patil, D. S.; Raja, D. S.; Chang, T.-G.; Lin, Ch.-H.; Shimakawa, K.; Wágner, T.

2014-01-01

Roč. 217, September (2014), s. 150-158 ISSN 0022-4596 Grant - others:AV ČR(CZ) M200501202 Program:M Institutional support: RVO:61389013 Keywords : metal -organic framework * lithium * carboxylate Subject RIV: CA - Inorganic Chemistry Impact factor: 2.133, year: 2014

CCDC 808551: Experimental Crystal Structure Determination : (4,7-Diphenyl-1,10-phenanthroline)-trifluoromethyl-silver tetrahydrofuran solvate

KAUST Repository

Weng, Zhiqiang; Lee, R.; Jia, Weiguo; Yuan, Yaofeng; Wang, Wenfeng; Feng, Xue; Huang, Kuo-Wei

2011-01-01

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from

CCDC 808552: Experimental Crystal Structure Determination : (4,7-Diphenyl-1,10-phenanthroline)(trifluoromethyl)-copper tetrahydrofuran solvate

KAUST Repository

Weng, Zhiqiang; Lee, R.; Jia, Weiguo; Yuan, Yaofeng; Wang, Wenfeng; Feng, Xue; Huang, Kuo-Wei

2011-01-01

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from

CCDC 808551: Experimental Crystal Structure Determination : (4,7-Diphenyl-1,10-phenanthroline)-trifluoromethyl-silver tetrahydrofuran solvate

KAUST Repository

Weng, Zhiqiang

2011-01-01

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

CCDC 808552: Experimental Crystal Structure Determination : (4,7-Diphenyl-1,10-phenanthroline)(trifluoromethyl)-copper tetrahydrofuran solvate

KAUST Repository

Weng, Zhiqiang

2011-01-01

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Electrochemistry of vanadocenedichloride in tetrahydrofuran and general scheme of 4B-6B subgroup metallocenedichlorides electroreduction

International Nuclear Information System (INIS)

Kukharenko, S.V.; Strelets, V.V.

1987-01-01

Mechanism of vanadocenedichloride Cp 2 VCl 2 electroreduction in THF, was investigated using polarography and cyclic voltammetry on mercury electrode. It was established that Cp 2 VCl 2 reversible single electron reduction up to metastable Cp 2 VCl 2 - which is dehalogenated reversibly with Cp 2 VCl formation takes place on the first cathode wave Cp 2 VCl irreversible single-electron reduction up to Cp 2 V proceeds on the second cathode wave. Cp 2 V reversible single-electron reduction on the third cathode wave results in formation of metastable Cp 2 V - anion as the primary product. The general scheme of electroreduction of metallocenedichlorides of transition element (Ti, Zr, Hf, V, Mo, W) series is suggested on the base of analyzing earlier obtained results

Synthesis of γ-amino[4-11C]butyric acid (GABA)

International Nuclear Information System (INIS)

Antoni, G.; Laangstroem, B.

1989-01-01

A one-pot synthesis of no-carrier added γ-amino[4- 11 C]butyric acid (GABA) starting with hydrogen [ 11 C]cyanide prepared from [ 11 C]carbon dioxide, is presented. Hydrogen [ 11 C]cyanide was trapped in tetrahydrofuran/potassium hydroxide in the presence of the amino polyether Krytofix 2.2.2. A Michael addition with ethyl acrylate followed by a selective reduction and hydrolysis of the resulting amino ester gave [4- 11 C]GABA. The radiochemical purity of GABA was higher than 99% and the decay corrected radiochemical yield was 60-65% based on the amount of H[ 11 C]CN used. The total synthesis time including purification was around 40 min, counted from the start of the Michael addition reaction. (Author)

Activity coefficients at infinite dilution measurements for organic solutes and water in the ionic liquid 4-methyl-N-butyl-pyridinium bis(trifluoromethylsulfonyl)-imide

Energy Technology Data Exchange (ETDEWEB)

Domanska, Urszula [Physical Chemistry Department, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw (Poland)], E-mail: ula@ch.pw.edu.pl; Marciniak, Andrzej [Physical Chemistry Department, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw (Poland)

2009-12-15

The activity coefficients at infinite dilution, {gamma}{sub 13}{sup {infinity}} for 36 solutes: alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, thiophene, tetrahydrofuran, ethers, acetone, and water in the ionic liquid 4-methyl-N-butyl-pyridinium bis(trifluoromethylsulfonyl)-imide [bmPY][NTf{sub 2}] were determined by gas-liquid chromatography at temperatures from 298.15 K to 368.15 K. The partial molar excess enthalpies at infinite dilution values {delta}H{sub 1}{sup E,{infinity}} were calculated from the experimental {gamma}{sub 13}{sup {infinity}} values obtained over the temperature range. The selectivity for different separation problems were calculated from the {gamma}{sub 13}{sup {infinity}} and compared to the literature values for other ionic liquids, N-methyl-2-pyrrolidinone (NMP) and sulfolane.

New hydride compounds of 1,4-diazabicyclo[2.2.2]octane and its dication with borine and tetrahydridoborate anion and products of their transformations; Novye gidridnye soedineniya 1,4-diazabitsiklo[2.2.2]oktana i ego dikationa s borinom i tetergidridoborat-anionom i produkty ikh prevrashcheniya

Energy Technology Data Exchange (ETDEWEB)

Shevchenko, Yu N; Yashina, N I; Markova, O Z; Trachevskij, V V

1997-12-31

New compounds [dabcoH{sub 2}](BH{sub 4}){sub 2}, dabco(BH{sub 3}){sub 2}2H{sub 2}, [dabco(BH{sub 3}){sub 2}H{sub 2}]{sub n} have been synthesized by means of interaction between dihydrochloride of 1,4-diazobicyclo[2.2.2] octane (dabco) and NaBH{sub 4} in the medium of nonaqueous solvents (glyme, diglyme, tetrahydrofuran, dimethylsulfoxide) and identified by the methods of element analysis, conductometry, {sup 1}H, {sup 11}B, {sup 14}N NMR, IR spectroscopy and thermal analysis. A mechanism is suggested and the conditions are defined for mutual transformations of the compounds studied. Their ability to bind reversibly molecular hydrogen has been revealed for the first time. 19 refs.; 3 figs.; 1 tab.

Highly efficient and enzymatic regioselective undecylenoylation of gastrodin in 2-methyltetrahydrofuran-containing systems.

Science.gov (United States)

Yang, Rongling; Liu, Xueming; Chen, Zhiyi; Yang, Chunying; Lin, Yaosheng; Wang, Siyuan

2014-01-01

Highly efficient and regioselective acylation of pharmacologically interesting gastrodin with vinyl undecylenic acid has been firstly performed through an enzymatic approach. The highest catalytic activity and regioselectivity towards the acylation of 7'-hydroxyl of gastrodin was obtained with Pseudomonas cepacia lipase. In addition, it was observed the lipase displayed higher activity in the eco-friendly solvent 2-methyltetrahydrofuran-containing systems than in other organic solvents. In the co-solvent mixture of tetrahydrofuran and 2-methyltetrahydrofuran (3/1, v/v), the reaction rate was 60.6 mM/h, substrate conversion exceeded 99%, and 7'-regioselectivity was 93%. It was also interesting that the lipase-catalyzed acylation couldn't be influenced by the benzylic alcohol in gastrodin. However, pseudomonas cepacia lipase displayed different regioselectivity towards gastrodin and arbutin.

Determination of Ivermectin in Medicated Feeds by Liquid Chromatography with Fluorescence Detection

Science.gov (United States)

2013-01-01

A labour- and time-effective analytical procedure for determination of ivermectin in medicated feed at recommended level of 2.0 mg kg−1 has been developed and validated. The analyte was extracted from grinded feed samples with acetonitrile and derivatisated with N-methylimidazole and trifluoracetic anhydride. The fluorescent derivatives were analysed by liquid chromatography method using C8 column. The isocratic conditions using acetonitrile, methanol, water, and tetrahydrofuran were applied. Fluorescence detection was performed at 365 nm (excitation) and 475 nm (emission) wavelengths. The total analysis time was 10 min. The validation results of the method (within-laboratory reproducibility 4.0% CV, mean recovery 100.1%) confirm the appropriate precision and accuracy of the developed method. PMID:24453835

Biomass pre-treatment for co-production of high-concentration C5- and C6-carbohydrates and their derivatives

Science.gov (United States)

Dumesic, James A.; Martin Alonso, David; Luterbacher, Jeremy Scott

2016-06-07

Described is a method of processing biomass to separate it into a liquid fraction enriched in solubilized C5-sugar-containing oligomers and C-5 sugar monomers and a solid fraction enriched in substantially insoluble cellulose and C6-sugar-containing oligomers. The method includes the steps of reacting biomass with a solvent system comprising water, at least one lactone, or at least one furan, or at least one cyclic ether, and at least one acid, for a time and at a temperature to yield the liquid and solid fractions. The liquid and solid fractions may then be separated. Gamma-valeroloactone is a preferred lactone for use in the solvent system. Tetrahydrofuran is a preferred furan species for use in the solvent system.

Choice of volatile component of fluoroplastics containing varnishes for the equipment of radiation protection technique

International Nuclear Information System (INIS)

Shigorina, I.I.; Egorov, B.N.; Timofeeva, L.N.

1978-01-01

The problems of choosing the volatile part (v.p.) for varnishes on the basis of different flourocopolymers are considered. Ketones, esters, freons, dimethylformamide, tetrahydrofuran, aromatic and chlorinated hydrocarbons have been used as solvents. The volatile component has been estimated by the quality of the varnish film obtained (transparency, bubbles), viscosity of the varnishes, completeness of solvent volatility, porosity degree. Besides, analyzed are such factors as kinetics of solvent evaporation, working life time of varnishes, and the degree of their inflammability. Optimum solvents and their mixtures have been found for different grades of fluorolones. The possibility of producing fluorolone lackuers with a reduced degree of inflammability and of incombustible fluorolone varnishes is shown. Fluorolone varnishes find ever increasing application for radiation-protective coating of the equipment

Effect of solution concentration on MEH-PPV thin films

Science.gov (United States)

Affendi, I. H. H.; Sarah, M. S. P.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

2018-05-01

MEH-PPV thin films were prepared with a mixture of THF (tetrahydrofuran) solution deposited by spin coating method. The surface topology of MEH-PPV thin film were characterize by atomic force microscopy (AFM) and optical properties of absorption spectra were characterized by using Ultraviolet-visible-near-infrared (UV-Vis-NIR). The MEH-PPV concentration variation affects the surface and optical properties of the thin film where 0.5 mg/ml MEH-PPV concentration have a good surface topology provided the same film also gives the highest absorption coefficient were then deposited to a TiO2 thin film forming composite layer. The composite layer then shows low current flow of short circuit current of Isc = -5.313E-7 A.

Influence of sample processing on the analysis of carotenoids in maize.

Science.gov (United States)

Rivera, Sol; Canela, Ramon

2012-09-21

We performed a number of tests with the aim to develop an effective extraction method for the analysis of carotenoid content in maize seed. Mixtures of methanol-ethyl acetate (6:4, v/v) and methanol-tetrahydrofuran (1:1, v/v) were the most effective solvent systems for carotenoid extraction from maize endosperm under the conditions assayed. In addition, we also addressed sample preparation prior to the analysis of carotenoids by liquid chromatography (LC). The LC response of extracted carotenoids and standards in several solvents was evaluated and results were related to the degree of solubility of these pigments. Three key factors were found to be important when selecting a suitable injection solvent: compatibility between the mobile phase and injection solvent, carotenoid polarity and content in the matrix.

Separation and quantitation of colour pigments of chili powder (Capsicum frutescens) by high-performance liquid chromatography-diode array detection.

Science.gov (United States)

Cserháti, T; Forgács, E; Morais, M H; Mota, T; Ramos, A

2000-10-27

The performance of reversed-phase thin-layer (RP-TLC) and reversed-phase high-performance liquid chromatography (RP-HPLC) was compared for the separation and determination of the colour pigments of chili (Capsicum frutescens) powder using a wide variety of eluent systems. No separation of pigments was achieved in RP-TLC, however, it was established that tetrahydrofuran shows an unusually high solvent strength. RP-HPLC using water-methanol-acetonitrile gradient elution separated the chili pigments in many fractions. Diode array detection (DAD) indicated that yellow pigments are eluted earlier than the red ones and chili powder contains more yellow pigments than common paprika powders. It was established that the very different absorption spectra of pigments make the use of DAD necessary.

Thermal and oxidative degradation studies of formulated C-ethers by gel-permeation chromatography

Science.gov (United States)

Jones, W. R., Jr.; Morales, W.

1982-01-01

Gel-permeation chromatography was used to analyze C-ether lubricant formulations from high-temperature bearing tests and from micro-oxidation tests. Three mu-styragel columns (one 500 and two 100 A) and a tetrahydrofuran mobile phase were found to adequately separate the C-ether degradation products. The micro-oxidation tests yielded degradation results qualitatively similar to those observed from the bearing tests. Micro-oxidation tests conducted in air yielded more degradation than did tests in nitrogen. No great differences were observed between the thermal-oxidative stabilities of the two C-ether formulations or between the catalytic degradation activities of silver and M-50 steel. C-ether formulation I did yield more degradation than did formulation II in 111- and 25-hour bearing tests, respectively.

Direct qualitative and quantitative determination of rare earths after separation by high pressure liquid chromatography (HPLC)

International Nuclear Information System (INIS)

Weuster, W.; Specker, H.

1980-01-01

The rare earths from lanthanum to erbium can be separated by means of HPLC in an eluent system containing di-isopropylether/tetrahydrofuran/nitric acid (100:30:3), and they are determined qualitatively and quantitatively after calibration. Fluorescence quenching of THF at break-through of the single elements serves as indication method. This quenching is proportional to the concentration. The calibration curve is linear within 0.2 to 0.02 moles input. Standards, ores (monazites, cerite earths, yttriae) and technical products were analysed qualitatively and quantitatively. The results obtained are in good agreement with analytical values from different methods. The relative standard deviation is 1.8-3% (N = 10). The procedure takes 50 min from dissolution of the analytical sample. (orig.) [de

ANIONIC POLYMERIZATION OF ALKYL METHACRYLATES INITIATED BY nBuCu(NCy2)Li

Institute of Scientific and Technical Information of China (English)

Bing-yong Han; Jian-guo Liang; Jian-min Lu; Feng An; Wan-tai Yang

2009-01-01

Anionic polymerization of methyl methacrylate (MMA), n-butyl methacrylate (nBMA) and glycidyl methacrylate (GMA) initiated by nBuCu(NCy2)Li (1) in tetrahydrofuran (THF) at -50℃ to -10℃ was investigated. It was found that the polymerization of MMA and nBMA initiated by 1 proceeded quantitatively in THF to afford PMMA and PBMA with polydispersity index 1.15-1.30 and nearly 100% initiator efficiencies at -10℃. The molecular weights increased linearly with the ratio of [monomer]/[1]. However, a post-polymerization experiment carried out on this system revealed a double polymer peak by GPC when fresh monomer was added after an interval of 10 rain. Polymerization of styrene could be initiated by 1, but the initiator efficiency was low.

Hydrodeoxygenation of vicinal OH groups over heterogeneous rhenium catalyst promoted by palladium and ceria support.

Science.gov (United States)

Ota, Nobuhiko; Tamura, Masazumi; Nakagawa, Yoshinao; Okumura, Kazu; Tomishige, Keiichi

2015-02-02

Heterogeneous ReOx-Pd/CeO2 catalyst showed excellent performance for simultaneous hydrodeoxygenation of vicinal OH groups. High yield (>99%), turnover frequency (300 h(-1)), and turnover number (10,000) are achieved in the reaction of 1,4-anhydroerythritol to tetrahydrofuran. This catalyst can be applied to sugar alcohols, and mono-alcohols and diols are obtained in high yields (≥85%) from substrates with even and odd numbers of OH groups, respectively. The high catalytic performance of ReOx-Pd/CeO2 can be assigned to rhenium species with +4 or +5 valence state, and the formation of this species is promoted by H2/Pd and the ceria support. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study of the solubility and stability of polystyrene wastes in a dissolution recycling process

International Nuclear Information System (INIS)

Garcia, Maria Teresa; Gracia, Ignacio; Duque, Gema; Lucas, Antonio de; Rodriguez, Juan Francisco

2009-01-01

Dissolution with suitable solvents is one of the cheapest and more efficient processes for polystyrene waste management. In this work the solubility of polystyrene foams in several solvents benzene, toluene, xylene, tetrahydrofuran, chloroform, 1,3-butanediol, 2-butanol, linalool, geraniol, d-limonene, p-cymene, terpinene, phellandrene, terpineol, menthol, eucalyptol, cinnamaldheyde, nitrobenzene, N,N-dimethylformamide and water has been determined. Experimental results have shown that to develop a 'green process' the constituents of essential oils, d-limonene, p-cymene, terpinene, phellandrene, are the most appropriate solvents. The action of these solvent does not produce any degradation of polymer chains. The solubility of the polymer in the mentioned solvents at different temperatures has been investigated. The solvent can be easily recycled by distillation.

Facile synthesis of water-soluble curcumin nanocrystals

Directory of Open Access Journals (Sweden)

Marković Zoran M.

2015-01-01

Full Text Available In this paper, facile synthesis of water soluble curcumin nanocrystals is reported. Solvent exchange method was applied to synthesize curcumin nanocrystals. Different techniques were used to characterize the structural and photophysical properties of curcumin nanocrystals. We found that nanocurcumin prepared by this method had good chemical and physical stability, could be stored in the powder form at room temperature, and was freely dispersible in water. It was established that the size of curcumin nanocrystals was varied in the range of 20-500 nm. Fourier transform infrared spectroscopy and UV-Vis analyses showed the presence of tetrahydrofuran inside the curcumin nanocrystals. Also, it was found that nanocurcumin emitted photoluminescencewith yellow-green colour. [Projekat Ministarstva nauke Republike Srbije, br. 172003

Preparation and hydrogen-deuterium exchange of alkyl and hydride bis(trimethylsilyl)amido derivatives of the actinide elements

International Nuclear Information System (INIS)

Simpson, S.J.; Turner, H.W.; Andersen, R.A.

1981-01-01

The monomeric, hydrocarbon-soluble monohydrides and monodeuterides of the actinide metals (thorium or uranium) of the type HM[N(SiMe 3 ) 2 ] 3 have been prepared. Their reaction chemistry - n-BuLi followed by MeBr yields MeM[N(SiMe 3 ) 2 ] 3 and borane in tetrahydrofuran yields BH 4 M[N(SiMe 3 ) 2 ] 3 - suggests that the hydrogen atom is hydridic. Pyrolysis of the hydrides yields the novel, four-membered ring metallacycle [(Me 3 Si) 2 N] 2 MCH 2 Si(Me) 2 NSiMe 3 where M is Th or U. These metallacycles are the key intermediates in the hydrogen-deuterium exchange reaction that yields ([CD 3 ) 3 Si] 2 N) 3 MD

Synthesis of styrene/isoprene/butadiene integrated rubber with wide glass transition temperature by reactive extrusion

Science.gov (United States)

Huang, Tianhua; Zheng, Anna; Zhan, Pengfei; Shi, Han; Li, Xiang; Guan, Yong; Wei, Dafu

2018-05-01

In this work, styrene/isoprene/butadiene integrated rubber (SIBR) was synthesized with n-butyllithium as the initiator and tetrahydrofuran as structure modifier in a co-rotating intermeshing twin-screw extruder. The content of diene in these terpolymers reached a surprising 70 wt% by feeding the monomers in two different sites of the twin-screw extruder. 1H-NMR, GPC and TEM results showed that the molecular structures of terpolymers changed with the variation of feeding site. Dynamic mechanical analysis of the vulcanized SIBR showed that the terpolymer had a wide glass transition region, which assured an excellent combination of high antiskid properties and low rolling resistance. Different from traditional solution polymerization, the present work provides a green approach to prepare the SIBR via bulk polymerization without solvent.

Tyrosinase Inhibition Type of Isolated Compounds Obtained from Pachyrhizus erosus

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Endang Lukitaningsih

2013-12-01

Full Text Available In Indonesia, Bengkoang (Phacyrhizus erosus have been used as one of cosmetics especially as sun screening and skin whitening materials. Six active compounds in Bengkoang with antioxidant and skin whitening activities have been isolated, namely daidzein, daidzin, genistin, (8,9-furanyl-pterocarpan-3-ol, 4-(2-(furane-2-ylethyl-2-methyl-2,5-dihydro-furane-3-carbaldehyde and 2-butoxy-2,5-bis(hydroxymethyl-tetrahydrofurane-3,4-diol. According to literatures, the type of their tyrosinase inhibitory activity has not yet reported. The determination of whitening activity of each compound was evaluated by the evaluation of Lineweaver-Burk plot. The result showed that five compounds had competitive inhibitory activity and 8,9-furanyl-pterocarpan-3-ol showed a non-competitive inhibition.

The combined effect of thermodynamic promoters tetrahydrofuran and cyclopentane on the kinetics of flue gas hydrate formation

DEFF Research Database (Denmark)

Daraboina, Nagu; von Solms, Nicolas

2015-01-01

) hydrate formation using a rocking cell apparatus. Hydrate formation and decomposition kinetics were investigated by constant cooling (hydrate nucleation temperature) and isothermal (hydrate nucleation time) methods. Improved (synergistic) hydrate formation kinetics (hydrate nucleation and growth) were...... of these two promoters is favorable both thermodynamically and kinetically for hydrate formation from flue gas....

Use of Cu+1 dopant and it's doping effects on polyaniline conducting system in water and tetrahydrofuran

Science.gov (United States)

Ali, Vazid; Kaur, Raminder; Kamal, Neel; Singh, Sukhmehar; Jain, S. C.; Kang, H. P. S.; Zulfequar, M.; Husain, M.

2006-04-01

The structural modification and properties of polymeric materials are of utmost importance in deciding their applications. In the present study, the synthesis of polyaniline (PANI) has been carried out via chemical oxidation in acidic medium by potassium-dichromate and the yield of synthesized polyaniline was found to be 75 80%. The copper per chlorate tetrabenzonitrile salt (CuClO4·4BN) used for chemical doping in synthesized polyaniline is stable in organic solvent like acetonitrile (AN) and benzonitrile (BN). The effect of Cu+1 oxidation state (dopant) in polyaniline has been characterized by FTIR. Electrical and dielectric measurements show the decrease in the intensity of the Cu+1 salt signal and the appearance of a radical signal due to the formation of oxidative coupled in polymeric species. Electrical and dielectric properties of doped polyaniline samples show significant changes due to the effect of dopant (CuClO4·4BN). It is observed that the conductivity is contributing both by formation of ionic complex and particularly dominated by electronic due to the mobility of charge carriers along the polyaniline chain.

Crystal structure of bis[1,3-bis(2,6-diisopropylphenylimidazol-2-ylidene]silver(I chloride tetrahydrofuran monosolvate

Directory of Open Access Journals (Sweden)

Inge Sänger

2015-05-01

Full Text Available In the title salt, [Ag(C27H36N22]Cl·C4H8O, the AgI atom is coordinated by two 1,3-bis(2,6-dimethylphenylimidazol-2-ylidene ligands. The imidazole rings are inclined to one another by 46.69 (13° and the benzene rings in each ligand are almost normal to the imdazole ring to which they are attached, with dihedral angles varying from 82.39 (13 to 88.27 (12°. There are C—H...π interactions present in the cation, involving the two ligands, and the solvent molecule is linked to the cation via a C—H...O hydrogen bond. In the crystal, molecules are linked by trifurcated C—H...(Cl,Cl,Cl hydrogen bonds, forming slabs parallel to (101. One isopropyl group is disordered over two sets of sites with an occupancy ratio of 0.447 (17:0.553 (17 and the THF molecule is disordered over two positions with an occupancy ratio of 0.589 (6:0.411 (6.

Enthalpies of solution, enthalpies of fusion and enthalpies of solvation of polyaromatic hydrocarbons: Instruments for determination of sublimation enthalpy at 298.15 K

Energy Technology Data Exchange (ETDEWEB)

Solomonov, Boris N., E-mail: boris.solomonov@ksu.ru; Varfolomeev, Mikhail A.; Nagrimanov, Ruslan N.; Mukhametzyanov, Timur A.; Novikov, Vladimir B.

2015-12-20

Graphical abstract: - Highlights: • Solution enthalpies of aromatic hydrocarbons were measured at 298.15 K. • Solution enthalpy of aromatic hydrocarbons in benzene is equal to their fusion enthalpy. • Method for calculation of solvation enthalpy of aromatic hydrocarbons was proposed. • Approach for estimation of aromatic hydrocarbons sublimation enthalpy was developed. • Obtained sublimation enthalpies coincide well with the recommended literature data. - Abstract: In this work a simple method for calculation of solvation enthalpies of polyaromatic hydrocarbons (PAHs) in various solvents at 298.15 K was proposed. According to this method the enthalpy of solvation of any polyaromatic hydrocarbon in a particular solvent can be calculated on the basis of the general formula of the compound, the solvation enthalpy of benzene in the same solvent and parameter related to the contribution of hydrogen atom into solvation enthalpy. The validity of the proposed method was confirmed by the comparison of calculated and experimentally measured values of solvation enthalpies of PAHs in benzene, tetrahydrofuran and acetonitrile. This method was used for determination of the sublimation enthalpy of PAHs at 298.15 K based on the general relationship between the enthalpy of sublimation/vaporization of the compound of interest and its enthalpies of solution and solvation in the same solvent at 298.15 K. Enthalpies of solution at infinite dilution of several PAHs were measured in acetonitrile, benzene and tetrahydrofuran at 298.15 K. It was shown that solution enthalpies of PAHs in benzene at 298.15 K are approximately equal to their fusion enthalpies at the melting temperature. Solvation enthalpies of 15 PAHs at 298.15 K calculated according to the proposed method together with corresponding fusion enthalpy values (at the melting temperature) were used to calculate the sublimation enthalpy values at 298.15 K. Comparison of the obtained results with recommended values of

A DFT study of solvation effects and NBO analysis on the tautomerism of 1-substituted hydantoin

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Meisam Shabanian

2016-09-01

Full Text Available 1-Substituted hydantoins (1-SH have been known as a benefit intermediate for producing agricultural and pharmaceuticals. The effect of solvent polarity on the tautomeric equilibria of 1-substituted hydantoin ring is studied by the density functional theory calculation (B3LYP/6–31++G(d,p level for predominant tautomeric forms of hydantoin derivatives (1-NO2, 1-CF3, 1-Br, 1-H, 1-CHCH2, 1-OH, 1-CH3 in the gas phase and selected solvents (benzene (non-polar solvent, tetrahydrofuran (THF (polar aprotic solvent and water (protic solvent. For electron withdrawing and releasing derivatives in the gas phase and solution Hy1 forms is more stable and dominant form. In addition variation of dipole moments and charges on atoms in the solvents are studied.

Time-resolved analysis of nonlinear optical limiting for laser synthesized carbon nanoparticles

Science.gov (United States)

Chen, G. X.; Hong, M. H.

2010-11-01

Nonlinear optical limiting materials have attracted much research interest in recent years. Carbon nanoparticles suspended in liquids show a strong nonlinear optical limiting function. It is important to investigate the nonlinear optical limiting process of carbon nanoparticles for further improving their nonlinear optical limiting performance. In this study, carbon nanoparticles were prepared by laser ablation of a carbon target in tetrahydrofuran (THF). Optical limiting properties of the samples were studied with 532-nm laser light, which is in the most sensitive wavelength band for human eyes. The shape of the laser pulse plays an important role for initializing the nonlinear optical limiting effect. Time-resolved analysis of laser pulses discovered 3 fluence stages of optical limiting. Theoretical simulation indicates that the optical limiting is initialized by a near-field optical enhancement effect.

4,5,7,8,17-Pentahydroxy-14,18-dimethyl-6-methylene-3,10-dioxapentacyclo[9.8.0.01,7.04,19.013,18]nonadec-14-ene-9,16-dione methanol solvate dihydrate

Directory of Open Access Journals (Sweden)

Chin Hoe Teh

2009-04-01

Full Text Available The title quassinoid compound, C20H24O9·CH3OH·2H2O, is a natural eurycomanone isolated from the roots of Eurycoma longifolia. The molecules contain a fused five-ring system, with one tetrahydrofuran ring adopting an envelope conformation, one tetrahydropyran-2-one ring in a screw boat conformation, one cyclohexenone ring in a half-chair conformation and two cyclohexane rings in chair conformations. Intramolecular C—H...O interactions generate S(5 ring motifs and an O—H...O interaction generates an S(7 ring motif. In the crystal, molecules are linked via intermolecular O—H...O interactions along the b axis and further stacked along a axis. The absolute configuration of the title compound was inferred from previously solved structures of its analogues.

Example of uranium(IV) insertion within a macrocyclic crown ether with coexistence of the metal in two oxidation states

Energy Technology Data Exchange (ETDEWEB)

Bombieri, G; De Paoli, G [Consiglio Nazionale delle Ricerche, Padua (Italy). Lab. di Chimica e Tecnologia dei Radioelementi; Immirzi, A

1978-01-01

Reaction of UCl/sub 4/ with 18-crown-6 in tetrahydrofuran yields (UCl/sub 4/)/sub 3/ (18-crown-6)/sub 2/ which on recrystallization in nitromethane, gives a partially oxidized and hydrolyzed product whose structure has been investigated by X-ray diffraction. The compound crystallizes in the orthorhombic system. The cell contains eight UCl/sub 3//sup +/ cations each inserted within a crown molecule and four (UO/sub 2/Cl/sub 3/(OH)(H/sub 2/O))/sup 2 -/anions having a pentagonal bipyramidal structure. Four solvated nitromethane molecules are also present. The compound represents one of the very few examples in which uranium exists in two oxidation states, and the first example in which its insertion within a crown macrocycle has been proved by an X-ray diffraction study.

Contributions to the analysis of nuclear raw materials

International Nuclear Information System (INIS)

Korkisch, J.; Abascal, F.; Hernandez, A.; Araico, E.

1976-01-01

A procedure to determine mg amounts of uranium in sodium diuranate samples was described. In this method the sample is dissolved in mineral acids and the uranium then determined titrimetrically after its reduction by means of ferrous sulfate in phosphoric acid solution. The titration was performed with standard potassium dichromate solution in the presence of barium diphenylamine sulphonate as indicator. This titration procedure is also very suitable for determination of uranium after its separation by means of anion exchange in a mixed aqueous-organic solvent system of 50 vol % tetrahydrofuran, 40 vol % methylglycol and 10 vol % 6 M hydrochloric acid. The method was used to determine the uranium in numerous yellow-cake samples from Mexico, uranium contents between 57 % and 71 % U 3 O 8 were found. (author)

Synthesis of selected 5-thio-substituted tetrazole derivatives and evaluation of their antibacterial and antifungal activities

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NALILU SUCHETHA KUMARI

2011-02-01

Full Text Available Several 5-thio-substituted tetrazole derivatives were efficiently synthesized by a three-step process. The substituted tetrazol-5-thiol, namely, 1-benzyl-1H-tetrazole-5-thiol (2 was prepared by refluxing commercially available benzyl isothiocyanate (1 with sodium azide in water. The second step was the synthesis of 1-benzyl-5-[(3-bromopropylthio]-1H-tetrazole (3 by thioalkylation of tetrazole-5-thiol 2 with 1,3-dibromopropane in tetrahydrofuran. Finally, the 5-thio-substituted tetrazole derivatives 4a–i were prepared by condensation of 3 with the corresponding amine or thiol. The structures of the newly synthesized compounds were characterized by NMR, LC/MS/MS, IR spectral data and elemental analysis. All the synthesized compounds were screened for their antibacterial and antifungal activities.

Highly efficient and enzymatic regioselective undecylenoylation of gastrodin in 2-methyltetrahydrofuran-containing systems.

Directory of Open Access Journals (Sweden)

Rongling Yang

Full Text Available Highly efficient and regioselective acylation of pharmacologically interesting gastrodin with vinyl undecylenic acid has been firstly performed through an enzymatic approach. The highest catalytic activity and regioselectivity towards the acylation of 7'-hydroxyl of gastrodin was obtained with Pseudomonas cepacia lipase. In addition, it was observed the lipase displayed higher activity in the eco-friendly solvent 2-methyltetrahydrofuran-containing systems than in other organic solvents. In the co-solvent mixture of tetrahydrofuran and 2-methyltetrahydrofuran (3/1, v/v, the reaction rate was 60.6 mM/h, substrate conversion exceeded 99%, and 7'-regioselectivity was 93%. It was also interesting that the lipase-catalyzed acylation couldn't be influenced by the benzylic alcohol in gastrodin. However, pseudomonas cepacia lipase displayed different regioselectivity towards gastrodin and arbutin.

Microtome Sliced Block Copolymers and Nanoporous Polymers as Masks for Nanolithography

DEFF Research Database (Denmark)

Shvets, Violetta; Schulte, Lars; Ndoni, Sokol

2014-01-01

Introduction. Block copolymers self-assembling properties are commonly used for creation of very fine nanostructures [1]. Goal of our project is to test new methods of the block-copolymer lithography mask preparation: macroscopic pieces of block-copolymers or nanoporous polymers with cross...... PDMS can be chemically etched from the PB matrix by tetrabutylammonium fluoride in tetrahydrofuran and macroscopic nanoporous PB piece is obtained. Both block-copolymer piece and nanoporous polymer piece were sliced with cryomicrotome perpendicular to the axis of cylinder alignment and flakes...... of etching patterns appear only under the certain parts of thick flakes and are not continuous. Although flakes from block copolymer are thinner and more uniform in thickness than flakes from nanoporous polymer, quality of patterns under nanoporous flakes appeared to be better than under block copolymer...

Introduction to the determination of transport numbers in electrolytic solutions. Effect of the activity coefficient in the coupled scattering and self-scattering processes. Electric mobility of the Na+ ion in water-THF mixture - Measurements of transport numbers by means of radio-tracers

International Nuclear Information System (INIS)

M'Malla

1976-01-01

Within the frame of a study of ion preferential solvation in hydro-organic media, the author reports some measurements of ionic conductivities of the Na + ion in mixtures of different proportions of water and THF (tetrahydrofuran), and more specifically the use of a recently developed method of transport number measurement. The author explains the general definition of the transport number, recalls usual measurement methods (Hittorf method, moving boundary method), describes the method principle, the measurement process, reports the assessment of corrective terms in the calculation of the transport number, and presents and comments the obtained results. A second part addresses the influence of activity coefficient gradient on the couple scattering and self-scattering phenomenon: self-scattering measurement with a tracer, theoretical aspects of coupled scattering, experimental results and discussion

Double concave cesium encapsulation by two charged sumanenyl bowls

Energy Technology Data Exchange (ETDEWEB)

Spisak, Sarah N.; Wei, Zheng; Petrukhina, Marina A. [Department of Chemistry, University at Albany, State University of New York, Albany, NY (United States); Rogachev, Andrey Yu. [Department of Chemistry, Illinois Institute of Technology, Chicago, IL (United States); Amaya, Toru [Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita (Japan); Hirao, Toshikazu [Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita (Japan); The Institute of Scientific and Industrial Research, Osaka University (Japan)

2017-03-01

The controlled reaction of Na and Cs, two alkali metals of different ionic sizes and binding abilities, with sumanene (C{sub 21}H{sub 12}) affords a novel type of organometallic sandwich [Cs(C{sub 21}H{sub 11}{sup -}){sub 2}]{sup -}, which crystallized as a solvent-separated ion pair with a [Na(18-crown-6)(THF){sub 2}]{sup +} cation (where THF=tetrahydrofuran). The unprecedented double concave encapsulation of a metal ion by two bowl-shaped sumanenyl anions in [Cs(C{sub 21}H{sub 11}{sup -}){sub 2}]{sup -} was revealed crystallographically. Evaluation of bonding and energetics of the remarkable product was accomplished computationally (B2PLYP-D/TZVP/ZORA), providing insights into its formation. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Reactions of Cp2MCl2 (M=Ti or Zr with Imine-Oxime Ligands. Formation of Metallacycles

Directory of Open Access Journals (Sweden)

C. Tripathi

2005-07-01

Full Text Available The reactions of bis(cyclopentadienyltitanium(IV/zirconium(IV dichloridewith a series of imine-oxime ligands (LH2, derived by condensing benzil-α-monoxime and2-phenylenediamine, 4-phenylenediamine, 4-methyl-2-phenylenediamine, 2,6-diamino-pyridine, have been studied in anhydrous tetrahydrofuran in the presence of base andmetallocycles of the [Cp2M(L] (M=Ti or Zr type have been isolated. Tentative structureshave been proposed for the products based on elemental analysis, electrical conductance andspectral (electronic, IR and 1H-NMR data. Proton NMR spectra indicate that on the NMRtime scale there is rapid rotation of the cyclopentadienyl ring around the metal-ring axis at25oC. Studies were conducted to assess the growth inhibiting potential of the complexessynthesized and the ligands against various bacterial strains.

Preparation of ordered silver angular nanoparticles array in block copolymer film for surface-enhanced Raman spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Svanda, J. [University of Chemistry and Technology, Department of Solid State Engineering (Czech Republic); Gromov, M. V. [University of Minnesota Duluth, Department of Chemistry and Biochemistry (United States); Kalachyova, Y. [University of Chemistry and Technology, Department of Solid State Engineering (Czech Republic); Postnikov, P. S. [Tomsk Polytechnic University, Department of Technology of Organic Substances and Polymer Materials (Russian Federation); Svorcik, V.; Lyutakov, O., E-mail: lyutakoo@vscht.cz [University of Chemistry and Technology, Department of Solid State Engineering (Czech Republic)

2016-10-15

We report a single-step method of preparation of ordered silver nanoparticles array through template-assisted nanoparticles synthesis in the semidried block copolymer film. Ordered nanoparticles were prepared on different substrates by the proper choice of solvents combination and preparation procedure. In particular, block copolymer and silver nitrate were dissolved in the mix of tetrahydrofuran, toluene, and n-methylpyrolidone. During short spin-coating procedure ordering of block copolymer, evaporation of toluene and preferential silver redistribution into poly(4-vinylpyridine) block occurred. Rapid heating of semidry film initiated silver reduction, removing of residual solvent and creation of ordered silver array. After polymer removing silver nanoparticles array was tested as a suitable candidate for subdiffraction plasmonic application–surface-enhanced Raman scattering. Enhancement factor was calculated and compared with the literature data.

Structural effects of a light emitting copolymer having perylene moieties in the side chain on the electroluminescent characteristics

International Nuclear Information System (INIS)

Lee, Chang Ho; Ryu, Seung Hoon; Jang, Hee Dong; Oh, Se Young

2004-01-01

We have synthesized a novel side chain light emitting copolymer. The side chain light emitting copolymer has a perylene moiety as an emitting unit and methylmethacrylate (MMA) as a spacer to decrease the concentration quenching of light emitting site in the polymer intrachain. These polymers are very soluble in most organic solvents such as monochlorobenzene, tetrahydrofuran, chloroform and benzene. The single-layered electroluminescent (EL) device consisting of ITO/carrier transporting copolymer and light emitting copolymer/Al was manufactured. The carrier transporting copolymer has triphenylamine moiety as a hole transporting unit and triazine moiety as an electron transporting unit in the polymer side chain. This device exhibits maximum external quantum efficiency when the MMA contents of light emitting copolymer is 30 wt.%. In particular, the device emits more blue light as MMA contents increase

2-(5-Iodo-2-oxoindolin-3-ylidenehydrazinecarbothioamide including an unknown solvate

Directory of Open Access Journals (Sweden)

Viviane Conceição Duarte de Bittencourt

2014-06-01

Full Text Available The molecule of the title compound, C9H7IN4OS, is almost planar (r.m.s. deviation = 0.0373 Å. In the molecule, N—H...N and N—H...O hydrogen bonds generate, respectively, S(5 and S(6 ring motifs. In the crystal, molecules are linked via N—H...O hydrogen bonds, forming chains propagating along [010]. These chains are linked via S...I contacts [3.4915 (16 Å], forming sheets lying parallel to (100. A region of disordered electron density, probably a disordered tetrahydrofuran solvent molecule, was treated using the SQUEEZE routine in PLATON [Spek (2009. Acta Cryst. D65, 148–155]. The formula mass and unit-cell characteristics were not taken into account during refinement.

Nanostructured oxygen sensor--using micelles to incorporate a hydrophobic platinum porphyrin.

Directory of Open Access Journals (Sweden)

Fengyu Su

Full Text Available Hydrophobic platinum(II-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorophenyl-porphyrin (PtTFPP was physically incorporated into micelles formed from poly(ε-caprolactone-block-poly(ethylene glycol to enable the application of PtTFPP in aqueous solution. Micelles were characterized using dynamic light scattering (DLS and atomic force microscopy (AFM to show an average diameter of about 140 nm. PtTFPP showed higher quantum efficiency in micellar solution than in tetrahydrofuran (THF and dichloromethane (CH₂Cl₂. PtTFPP in micelles also exhibited higher photostability than that of PtTFPP suspended in water. PtTFPP in micelles exhibited good oxygen sensitivity and response time. This study provided an efficient approach to enable the application of hydrophobic oxygen sensors in a biological environment.

A Rapid Determination of Cinnarizine in Bulk and Pharmaceutical Dosage Form by LC

Directory of Open Access Journals (Sweden)

A. A. Heda

2010-01-01

Full Text Available A simple, selective, rapid and precise reverse phase high pressure liquid chromatographic method has been developed for the estimation of cinnarizine from pharmaceutical formulation. The method was developed using MICRA-NPS C18 (length×OD×ID =33×8.0×6.0 mm, 1.5 μm column with a mobile phase consisting of acetonitrile, triethylamine buffer (adjusted to pH 4.5 with 10% w/v potassium hydroxide and tetrahydrofuran in the ratio 30:66:4 respectively, at a flow rate of 0.5 mL/min. Wavelength was fixed at 253 nm. The developed method was validated for linearity, accuracy, precision, limit of detection and limit of quantitation. The proposed method can be used for the routine estimation of cinnarizine in pharmaceutical dosage form.

Heronapyrrole D: A case of co-inspiration of natural product biosynthesis, total synthesis and biodiscovery

Directory of Open Access Journals (Sweden)

Jens Schmidt

2014-05-01

Full Text Available The heronapyrroles A–C have first been isolated from a marine-derived Streptomyces sp. (CMB-0423 in 2010. Structurally, these natural products feature an unusual nitropyrrole system to which a partially oxidized farnesyl chain is attached. The varying degree of oxidation of the sesquiterpenyl subunit in heronapyrroles A–C provoked the hypothesis that there might exist other hitherto unidentified metabolites. On biosynthetic grounds a mono-tetrahydrofuran-diol named heronapyrrole D appeared a possible candidate. We here describe a short asymmetric synthesis of heronapyrrole D, its detection in cultivations of CMB-0423 and finally the evaluation of its antibacterial activity. We thus demonstrate that biosynthetic considerations and the joint effort of synthetic and natural product chemists can result in the identification of new members of a rare class of natural products.

Gas phase radiolysis and vacuum ultraviolet photolysis of heterocyclic organic compounds. Progress report, February 1, 1974--February 1, 1975

International Nuclear Information System (INIS)

Scala, A.A.; Salomon, D.; Colon, I.; D'Angona, J.

1975-01-01

In the γ radiolysis of tetrahydrofuran there are pronounced density effects in the pressure range from 0 to 50 Torr with the most important ion-pair yields decreasing as the pressure increases. The relative product yields of the radiolysis is compared with that of xenon photolysis. Possible mechanisms to explain the results obtained are discussed. The ion-pair yields from the γ radiolysis of the heterocyclic amines, ethylenimine, azetidine, pyrrolidine, and piperidine, are determined, and the pressure effects are evaluated. Reactions mechanisms are discussed. The vacuum ultraviolet photolysis products of thietane and tetrahydrothiophene are studied and compared with the γ radiolysis products. Reaction mechanisms are discussed. The status of the construction of a photoionization mass spectrometer and the measurement of the ionization efficiencies and extinction coefficients of organic compounds is reported. (U.S.)

Modeling thermodynamic properties of propane or tetrahydrofuran mixed with carbon dioxide or methane in structure-II clathrate hydrates

NARCIS (Netherlands)

Fang, Bin; Ning, Fulong; Cao, Pinqiang; Peng, Li; Wu, Jianyang; Zhang, Zhun; Vlugt, T.J.H.; Kjelstrup, Signe

2017-01-01

A sound knowledge of thermodynamic properties of sII hydrates is of great importance to understand the stability of sII gas hydrates in petroleum pipelines and in natural settings. Here, we report direct molecular dynamics (MD) simulations of the thermal expansion coefficient, the

Excess enthalpies of the ternary mixtures: {tetrahydrofuran + 3-methylpentane + (octane or decane)} at the temperature 298.15 K

International Nuclear Information System (INIS)

Wang Zhaohui; Benson, George C.; Lu, Benjamin C.-Y.

2003-01-01

Measurements of excess molar enthalpies at the temperature 298.15 K in a flow microcalorimeter, are reported for the two ternary mixtures {X 1 C 4 H 8 O + X 2 CH 3 CH 2 CH(CH 3 )CH 2 CH 3 + (1-X 1 -X 2 )CH 3 (CH 2 ) v-2 CH 3 } with v=8 and 10. Smooth representations of the results are described and used to construct constant-enthalpy contours on Roozeboom diagrams. It is shown that useful estimates of the ternary enthalpies can be obtained from the Liebermann-Fried model, using only the physical properties of the components and their binary mixtures

Hydrogen storage in double clathrates with tert-butylamine.

Science.gov (United States)

Prasad, Pinnelli S R; Sugahara, Takeshi; Sum, Amadeu K; Sloan, E Dendy; Koh, Carolyn A

2009-06-18

The first proof-of-concept of the formation of a double tert-butylamine (t-BuNH(2)) + hydrogen (H(2)) clathrate hydrate has been demonstrated. Binary clathrate hydrates with different molar concentrations of the large guest t-BuNH(2) (0.98-9.31 mol %) were synthesized at 13.8 MPa and 250 K, and characterized by powder X-ray diffraction and Raman microscopy. A structural transformation from sVI to sII of t-BuNH(2) hydrate was clearly observed under hydrogen pressures. Raman spectroscopic data suggested that the hydrogen molecules occupied the small cages and had similar occupancy to hydrogen in the double tetrahydrofuran (THF) + H(2) clathrate hydrate. The hydrogen storage capacity in this system was approximately 0.7 H(2) wt % at the molar concentration of t-BuNH(2) close to the sII stoichiometry.

The absorption of iodine-131 on a ceramic matrix

International Nuclear Information System (INIS)

Han, H.S.; Park, U.J.; Dash, A.

2004-01-01

The retention of 131 I on ceramic rod coated with silver nitrate followed by coating with a polyurethane membrane to be applied in brachytherapy was studied. The concentration of silver nitrate (20 g/l), the volume of 131 I as a sodium iodide solution (100 μl), the pH of the reaction mixture (pH 9) etc., were optimized to get a maximum uptake on the ceramic rod. The concentration of coating solution (5%, polyurethane in tetrahydrofuran) was also optimized to obtain a minimum leaching of 131 I activity in normal saline solution. After coating with a polyurethane membrane, the 131 I absorbed on the ceramic rod exhibited low leachability (0.03%). This method can be applied for the preparation of 125 I interstitial sources to be used in eye and prostate cancer therapy. (author)

Investigation of electric conductivity, viscosity and density of LiBF4-1,3-dioxolane system in homogeneity region

International Nuclear Information System (INIS)

Plakhotnik, V.N.; Tovmash, N.F.; Mishustin, A.N.; Dam'e, V.N.

1987-01-01

Solutions of lithium tetrafluoborate in 1,3-dioxolane (DOL) in temperature range and concentrations limiting the homogeneity region from the side of salt crystallization and formation of polymer structures from -30 deg to +25 deg and from 10 -6 to 1.4 mol/l. are investigated using methods of conductometry, densimetry, viscosimetry and by measuring time of spinlattice 7 Li nuclei relaxation. The dissociation constant of LiBF 4 in DOL (pK D =4.9±0.2 at 25 deg) is determined. Comparison with systems based on 1,2-dimethoxyethane and tetrahydrofurane studied earlier is carried out. Suppositions concerning considerable contribution of ion molecular structures with participation of salt ions and solvent molecules to electric conductivity are stated, and it agrees with the data on measurements of velocities of spin-lattice relaxation of 7 Li nuclei

Investigation of electric conductivity, viscosity and density of LiBF/sub 4/-1,3-dioxolane system in homogeneity region

Energy Technology Data Exchange (ETDEWEB)

Plakhotnik, V N; Tovmash, N F; Mishustin, A N; Dam' e, V N

1987-01-01

Solutions of lithium tetrafluoborate in 1,3-dioxolane (DOL) in temperature range and concentrations limiting the homogeneity region from the side of salt crystallization and formation of polymer structures from -30 deg to +25 deg and from 10/sup -6/ to 1.4 mol/l. are investigated using methods of conductometry, densimetry, viscosimetry and by measuring time of spinlattice /sup 7/Li nuclei relaxation. The dissociation constant of LiBF/sub 4/ in DOL (pK/sub D/=4.9+-0.2 at 25 deg) is determined. Comparison with systems based on 1,2-dimethoxyethane and tetrahydrofurane studied earlier is carried out. Suppositions concerning considerable contribution of ion molecular structures with participation of salt ions and solvent molecules to electric conductivity are stated, and it agrees with the data on measurements of velocities of spin-lattice relaxation of /sup 7/Li nuclei.

Volumetric Properties of the Ionic Liquid, 1-Butyl-3-methylimidazolium Tetrafluoroborate, in Organic Solvents at T = 298.15K

Science.gov (United States)

Shekaari, Hemayat; Zafarani-Moattar, Mohammed Taghi

2008-04-01

Apparent molar volumes, V_φ , and compressibilities, kappa _φ , of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]) have been determined from precise density and speed-of-sound measurements in organic solvents, methanol (MeOH), acetonitrile (MeCN), tetrahydrofuran (THF), N, N-dimethylacetamide (DMA), and dimethylsulfoxide (DMSO) in the dilute region of the ionic liquid. Corresponding values at infinite dilution are estimated by the Redlich-Mayer and Pitzer equations. The results have been interpreted by the interaction of the [BMIm][BF4] in the organic solvents. Results show that the structure and dielectric constant of the organic solvents play an important role for the ion-solvent interactions in these mixtures. It was found that the strength of interaction between [BMIm][BF4] with the studied organic solvents has the order DMSO > DMA > MeOH > MeCN > THF.

Simple home-made sensors for potentiometric titrations

International Nuclear Information System (INIS)

Selig, W.

1982-04-01

A sensor for potentiometric titrations was prepared by coating a spectroscopic graphite rod with a solution of poly(vinyl chloride) and dioctyphthalate in tetrahydrofuran. The reference electrode was an Ag/AgCl single-junction electrode. The sensor was used in precipitation, acid-base, compleximetric, and redox titrations. Preparation of the coated-graphite sensor is simple and rapid. Moreover, it is quite inexpensive. A limitation is its applicability in aqueous media only, because organic solvents will dissolve the membrane. Various uncoated types of graphite have also been investigated as sensors, particularly in two applications of interest in the analysis of propellants: the titration of nitroform and perchlorate. Obviously, these sensors can be used also in nonaqueous, or partially nonaqueous media. These sensors may also find use in the potentiometric titration of fluoride vs La(III) or Th

Catalytic activation of molecular hydrogen in alkyne hydrogenation reactions by lanthanide metal vapor reaction products

International Nuclear Information System (INIS)

Evans, W.J.; Bloom, I.; Engerer, S.C.

1983-01-01

A rotary metal vapor was used in the synthesis of Lu, Er, Nd, Sm, Yb, and La alkyne, diene, and phosphine complexes. A typical catalytic hydrogenation experiment is described. The lanthanide metal vapor product is dissolved in tetrahydrofuran or toluene and placed in a pressure reaction vessel 3-hexyne (or another substrate) is added, the chamber attached to a high vacuum line, cooled to -196 0 C, evacuated, warmed to ambient temperature and hydrogen is added. The solution is stirred magnetically while the pressure in monitored. The reaction products were analyzed by gas chromatography. Rates and products of various systems are listed. This preliminary survey indicates that catalytic reaction chemistry is available to these metals in a wide range of coordination environments. Attempts to characterize these compounds are hampered by their paramagnetic nature and their tendency to polymerize

A facile approach to fabricate hierarchically structured poly(3-hexylthiophene-2,5-diyl) films

DEFF Research Database (Denmark)

Zhang, Weihua; Zong, Chuanyong; Xie, Jixun

2017-01-01

Microstructured surfaces have great potentials to improve the performances and efficiency of optoelectronic devices. In this work, a simple robust approach based on surface instabilities was presented to fabricate poly(3-hexylthiophene-2,5-diyl) (P3HT) films with ridge-like/wrinkled composite...... microstructures. Namely, the hierarchically patterned films were prepared by spin coating the P3HT/tetrahydrofuran (THF) solution on a polydimethylsiloxane (PDMS) substrate to form stable ridge-like structures, followed by solvent vapor swelling to create surface wrinkles with the orientation guided by the ridge......-like structures. During spin coating of the P3HT/THF solution, the ridge-like structures were generated by the in-situ template of the THF swelling-induced creasing structures on the PDMS substrate. To our knowledge, it is the first report that the creasing structures are used as a recoverable template...

Electrospun Nanocomposite Materials, A Novel Synergy of Polyurethane and Bovine Derived Hydroxyapatite

Science.gov (United States)

Bozkurt, Y.; Sahin, A.; Sunulu, A.; Aydogdu, M. O.; Altun, E.; Oktar, F. N.; Ekren, N.; Gunduz, O.

2017-04-01

Polyurethane (PU) is a synthetic polymer that is used for construction of scaffold in tissue engineering applications in order to obtain desirable mechanical, physical and chemical properties like elasticity and durability. Bovine derived hydroxyapatite (BHAp) is a ceramic based natural polymer that is used as the most preferred implant material in orthopedics and dentistry due to their chemically and biologically similarity to the mineral phase found in the human bone structure. PU and bovine derived hydroxyapatite (BHAp) solutions with different concentrations were prepared with dissolving polyurethane and BHAp in Dimethylformamide (DMF) and Tetrahydrofuran (THF) solutions. Blended PU-BHAp solutions in different concentrations were used for electrospinning technique to create nanofiber scaffolds and new biocomposite material together. SEM, FTIR and physical analysis such as viscosity, electrical conductivity, density measurement and tensile strength measurement tests were carried out after production process.

Study of the parameters solution blow spinning technique in the obtaining of mullite nanofibers; Estudo de parametros da tecnica de fiacao por sopro em solucao na obtencao de nanofibras de mulita

Energy Technology Data Exchange (ETDEWEB)

Severo, L.L.; Farias, R.M.C.; Menezes, R.R.; Santos, M.A., E-mail: lucasleite_14.1@hotmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

2016-07-01

The Solution Blow Spinning (SBS) technique which use aerodynamic forces and has a high production rate, was created for production of nanofiber with versatile way, such as electrospinning. Therefore, the objective is to analyze the process parameters in order to optimize the production of mullite nanofiber using the SBS technique to determine the influence of air pressure, the concentration of the polymer and ejection rate in the diameter of the fibers. For this, it was used PVC as polymer in spinning, tetrahydrofuran as the solvent, HCl as acidifying, aluminum nitrate nonahydrate and tetraethylorthosilicate as precursors of mullite. The nanofibers obtained were heat treated at 1100°C. From of XRD and SEM results, it was proved the achievement of mullite nanofiber, and STATISTICA 7 software revealed that only ejection rate and the concentration influence in the average diameters of the fibers. (author)

Lipophilic polyelectrolyte gel derived from phosphonium borate can absorb a wide range of organic solvents.

Science.gov (United States)

Sunaga, Sokuro; Kokado, Kenta; Sada, Kazuki

2018-01-24

Herein, we demonstrate a polyelectrolyte gel which can absorb a wide range of organic solvents from dimethylsulfoxide (DMSO, permittivity: ε = 47.0) to tetrahydrofuran (ε = 5.6). The gel consists of polystyrene chains with small amounts (∼5 mol%) of lipophilic electrolytes derived from triphenylphosphonium tetraaryl borate. The swelling ability of the polyelectrolyte gel was higher than that of the alkyl ammonium tetraaryl borate previously reported by us, and this is attributed to the higher compatibility with organic solvents, as well as the higher dissociating ability, of the triphenyl phosphonium salt. The role of the ionic moieties was additionally confirmed by post modification of the polyelectrolyte gel via a conventional Wittig reaction, resulting in a nonionic gel. Our findings introduced here will lead to a clear-cut molecular design for polyelectrolyte gels which absorb all solvents.

Analogues of the muscarinic agent 2'-methylspiro[1-azabicyclo[2.2.2]octane-3,4'-[1,3]dioxolane]: synthesis and pharmacology.

Science.gov (United States)

Nordvall, G; Sundquist, S; Glas, G; Gogoll, A; Nilvebrant, L; Hacksell, U

1992-05-01

A number of tetrahydrofuran analogues of 2'-methylspiro[1-azabicyclo[2.2.2]octane-3,4'-[1,3]dioxolane] (1) have been prepared with the aim to obtain information about the relative importance of each of the oxygens in 1 for efficacy and for selectivity. In addition, the dimethyl and desmethyl analogues of 1 were prepared. The new compounds were compared to cis- and trans-1 with regard to their ability to displace (-)-[3H]-3-quinuclidinyl benzilate ((-)-[3H]QNB) from muscarinic receptors in cerebral cortex, heart, parotid gland, and urinary bladder from guinea pigs. Functional studies were made on isolated guinea pig bladder and ileum. The new compounds exhibited both lower affinity and efficacy than cis-1. A conformational study was performed, and the effects of steric and electronic factors on the biological activity of the compounds are discussed.

Field and laboratory determination of a poly(vinyl/vinylidene chloride) additive in brick mortar.

Science.gov (United States)

Law, S L; Newman, J H; Ptak, F L

1990-02-01

A polymerized vinyl/vinylidene chloride additive, used in brick mortar during the 60s and 70s, is detected at the building site by the field method, which employs a commercially available chloride test strip. The field test results can then be verified by the laboratory methods. In one method, total chlorine in the mortar is determined by an oxygen-bomb method and the additive chloride is determined by difference after water-soluble chlorides have been determined on a separate sample. In the second method, the polymerized additive is extracted directly from the mortar with tetrahydrofuran (THF). The difference in weight before and after extraction of the additive gives the weight of additive in the mortar. Evaporation of the THF from the extract leaves a thin film of the polymer, which gives an infrared "fingerprint" spectrum characteristic of the additive polymer.

Preparation of Two-Layer Anion-Exchange Poly(ethersulfone Based Membrane: Effect of Surface Modification

Directory of Open Access Journals (Sweden)

Lucie Zarybnicka

2016-01-01

Full Text Available The present work deals with the surface modification of a commercial microfiltration poly(ethersulfone membrane by graft polymerization technique. Poly(styrene-co-divinylbenzene-co-4-vinylbenzylchloride surface layer was covalently attached onto the poly(ethersulfone support layer to improve the membrane electrochemical properties. Followed by amination, a two-layer anion-exchange membrane was prepared. The effect of surface layer treatment using the extraction in various solvents on membrane morphological and electrochemical characteristics was studied. The membranes were tested from the point of view of water content, ion-exchange capacity, specific resistance, permselectivity, FT-IR spectroscopy, and SEM analysis. It was found that the two-layer anion-exchange membranes after the extraction using tetrahydrofuran or toluene exhibited smooth and porous surface layer, which resulted in improved ion-exchange capacity, electrical resistance, and permselectivity of the membranes.

Liquid chromatographic analysis of a formulated ester from a gas-turbine engine test

Science.gov (United States)

Jones, W. R., Jr.; Morales, W.

1983-01-01

Size exclusion chromatography (SEC) utilizing mu-Bondagel and mu-Styragel columns with a tetrahydrofuran mobile phase was used to determine the chemical degradation of lubricant samples from a gas-turbine engine test. A MIL-L-27502 candidate, ester-based lubricant was run in a J57-29 engine at a bulk oil temperature of 216 C. In general, the analyses indicated a progressive loss of primary ester, additive depletion, and formation of higher molecular weight material. An oil sample taken at the conclusion of the test showed a reversal of this trend because of large additions of new oil. The high-molecular-weight product from the degraded ester absorbed strongly in the ultraviolet region at 254 nanometers. This would indicate the presence of chromophoric groups. An analysis of a similar ester lubricant from a separate high-temperature bearing test yielded qualitatively similar results.

Photostabilizing Efficiency of PVC in the Presence of Schiff Bases as Photostabilizers

Directory of Open Access Journals (Sweden)

Emad Yousif

2015-11-01

Full Text Available The photostabilization of polyvinyl chloride (PVC films by Schiff bases was investigated. Polyvinyl chloride films containing 0.5 wt % Schiff bases were produced using the same casting method as that used for additive-free PVC films from tetrahydrofuran (THF solvent. The photostabilization activities of these compounds were determined by monitoring the carbonyl, polyene and hydroxyl indices with irradiation time. The changes in viscosity average molecular weight of PVC with irradiation time were also monitored using THF as a solvent. The quantum yield of chain scission (Φcs for the studied complexes in PVC was estimated to range between 4.72 and 8.99 × 10−8. According to the experimental results, several mechanisms were suggested, depending on the structure of the additive. Ultra violet (UV absorption, peroxide decomposition and radical scavenging were suggested as the photostabilizing mechanisms.

Dip-pen nanopatterning of photosensitive conducting polymer using a monomer ink

Science.gov (United States)

Su, Ming; Aslam, Mohammed; Fu, Lei; Wu, Nianqiang; Dravid, Vinayak P.

2004-05-01

Controlled patterning of conducting polymers at a micro- or nanoscale is the first step towards the fabrication of miniaturized functional devices. Here, we introduce an approach for the nanopatterning of conducting polymers using an improved monomer "ink" in dip-pen nanolithography (DPN). The nominal monomer "ink" is converted, in situ, to its conducting solid-state polymeric form after patterned. Proof-of-concept experiments have been performed with acid-promoted polymerization of pyrrole in a less reactive environment (tetrahydrofuran). The ratios of reactants are optimized to give an appropriate rate to match the operation of DPN. A similar synthesis process for the same polymer in its bulk form shows a high conductance and crystalline structure. The miniaturized conducting polymer sensors with light detection ability are fabricated by DPN using the improved ink formula, and exhibit excellent response, recovery, and sensitivity parameters.

Dip-pen nanopatterning of photosensitive conducting polymer using a monomer ink

International Nuclear Information System (INIS)

Su Ming; Aslam, Mohammed; Fu Lei; Wu Nianqiang; Dravid, Vinayak P.

2004-01-01

Controlled patterning of conducting polymers at a micro- or nanoscale is the first step towards the fabrication of miniaturized functional devices. Here, we introduce an approach for the nanopatterning of conducting polymers using an improved monomer 'ink' in dip-pen nanolithography (DPN). The nominal monomer 'ink' is converted, in situ, to its conducting solid-state polymeric form after patterned. Proof-of-concept experiments have been performed with acid-promoted polymerization of pyrrole in a less reactive environment (tetrahydrofuran). The ratios of reactants are optimized to give an appropriate rate to match the operation of DPN. A similar synthesis process for the same polymer in its bulk form shows a high conductance and crystalline structure. The miniaturized conducting polymer sensors with light detection ability are fabricated by DPN using the improved ink formula, and exhibit excellent response, recovery, and sensitivity parameters

Highly Sensitive and Selective Gas Sensor Using Hydrophilic and Hydrophobic Graphenes

Science.gov (United States)

Some, Surajit; Xu, Yang; Kim, Youngmin; Yoon, Yeoheung; Qin, Hongyi; Kulkarni, Atul; Kim, Taesung; Lee, Hyoyoung

2013-01-01

New hydrophilic 2D graphene oxide (GO) nanosheets with various oxygen functional groups were employed to maintain high sensitivity in highly unfavorable environments (extremely high humidity, strong acidic or basic). Novel one-headed polymer optical fiber sensor arrays using hydrophilic GO and hydrophobic reduced graphene oxide (rGO) were carefully designed, leading to the selective sensing of volatile organic gases for the first time. The two physically different surfaces of GO and rGO could provide the sensing ability to distinguish between tetrahydrofuran (THF) and dichloromethane (MC), respectively, which is the most challenging issue in the area of gas sensors. The eco-friendly physical properties of GO allowed for faster sensing and higher sensitivity when compared to previous results for rGO even under extreme environments of over 90% humidity, making it the best choice for an environmentally friendly gas sensor. PMID:23736838

Acidic resin-catalysed conversion of fructose into furan derivatives in low boiling point solvents.

Science.gov (United States)

Zhu, Hong; Cao, Quan; Li, Chunhu; Mu, Xindong

2011-09-27

Conversion of fructose into furan derivatives 5-hydroxymethylfurfural (HMF) and 5-methoxymethylfurfural (MMF) is performed in tetrahydrofuran (THF) and methanol-organic solvent systems, catalysed by an acidic resin Amberlyst-15. The melted fructose can be converted into HMF on the surface of the solid resin catalyst in the presence of THF as an extracting phase, which is a good solvent for HMF and other by-products. The solid resin catalyst can be reused eleven times without losing its catalytic ability, with an average HMF yield of approximately 50%. Upon the addition of methanol, the generated HMF can further react with methanol to form MMF, and the total yield of HMF and MMF could be promoted to 65%. GC-MS analysis confirms the formation of a small amount of methyl levulinate in methanolorganic solvent system. Copyright © 2011 Elsevier Ltd. All rights reserved.

Synthetic and mechanistic aspects of titanium-mediated carbonyl olefinations

Energy Technology Data Exchange (ETDEWEB)

Petasis, N.A.; Staszewski, J.P.; Hu, Yong-Han; Lu, Shao-Po [Univ. of Southern California, Los Angeles, CA (United States)

1995-12-31

A new method for the olefination of carbonyl compounds with dimethyl titanocene, and other related bishydrocarbyl titanocene derivatives has been recently developed in the author`s laboratories. This process is experimentally convenient and works with various types of carbonyl compounds, including aldehydes, ketones, esters, lactones, carbonates, anhydrides, amides, imides, lactams, thioesters, selenoesters, and acylsilanes. More recent studies have focused on the scope and utility of this reaction, including mechanistic studies and synthetic applications. In addition to varying the reaction conditions, the authors have examined several mixed titanocene derivatives and have found ways for carrying out this type of olefination at room temperature, such as the use of tris(trimethylsilyl) titanacyclobutene. The authors have also employed this reaction in the modification of carbohydrates and cyclobutenediones. This olefination was also followed-up with subsequent transformations to produce carbocycles and heterocycles, including tetrahydrofurans and tetrahydropyrans.

Block copolymer battery separator

Science.gov (United States)

Wong, David; Balsara, Nitash Pervez

2016-04-26

The invention herein described is the use of a block copolymer/homopolymer blend for creating nanoporous materials for transport applications. Specifically, this is demonstrated by using the block copolymer poly(styrene-block-ethylene-block-styrene) (SES) and blending it with homopolymer polystyrene (PS). After blending the polymers, a film is cast, and the film is submerged in tetrahydrofuran, which removes the PS. This creates a nanoporous polymer film, whereby the holes are lined with PS. Control of morphology of the system is achieved by manipulating the amount of PS added and the relative size of the PS added. The porous nature of these films was demonstrated by measuring the ionic conductivity in a traditional battery electrolyte, 1M LiPF.sub.6 in EC/DEC (1:1 v/v) using AC impedance spectroscopy and comparing these results to commercially available battery separators.

EFSA CEF Panel (EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids), 2016 Scientific Opinion on Flavouring Group Evaluation 75, Revision 1 (FGE.75Rev1): Consideration of tetrahydrofuran derivatives evaluated by JECFA (63rd meeting) structurally related to tetrahydrofuran

DEFF Research Database (Denmark)

Beltoft, Vibe Meister; Nørby, Karin Kristiane

The Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF) of the EFSA was requested to consider evaluations of flavouring substances assessed since 2000 by the Joint FAO/WHO Expert Committee on Food Additives (the JECFA), and to decide whether further evaluation is neces......The Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF) of the EFSA was requested to consider evaluations of flavouring substances assessed since 2000 by the Joint FAO/WHO Expert Committee on Food Additives (the JECFA), and to decide whether further evaluation...... for anhydrolinalool oxide (5) [FL-no: 13.097]. The substances were evaluated through a stepwise approach that integrates information on structure-activity relationships, intake from current uses, toxicological threshold of concern, and available data on metabolism and toxicity. The JECFA concluded all the 11...... with the JECFA conclusion ‘No safety concern at estimated level of intake as flavouring substances’ based on the maximised survey-derived daily intake (MSDI) approach. The specifications for the materials of commerce have also been considered and for all 11 substances, the information is adequate....

Resonance energy transfer from quinolinone modified polystyrene-block-poly(styrene-alt-maleic anhydride) copolymer to terbium(III) metal ions

Energy Technology Data Exchange (ETDEWEB)

Výprachtický, Drahomír, E-mail: vyprachticky@imc.cas.cz [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovský Sq. 2, 162 06 Prague 6 (Czech Republic); Mikeš, František [New York University Polytechnic School of Engineering, Polymer Research Institute, 6 MetroTech Center, Brooklyn, NY 11201 (United States); Lokaj, Jan; Pokorná, Veronika; Cimrová, Věra [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovský Sq. 2, 162 06 Prague 6 (Czech Republic)

2015-04-15

Polystyrene-block-poly(styrene-alt-maleic anhydride) was synthesized by nitroxide mediated radical polymerization and modified with 7-amino-4-methylquinolin-2(1H)-one (I) and methanol. The formed block polymer ligand contained a quinolinone fluorophore (Ω) and carboxyl (III) or sodium carboxylate (IV) binding sites. The ligand-to-metal resonance energy transfer (RET) and ligand binding properties of [III–Tb{sup 3+}] and [IV–Tb{sup 3+}] complexes were investigated by steady-state and time-resolved luminescence spectroscopy in tetrahydrofuran/methanol and/or tetrahydrofuran/deuterated methanol mixtures and compared with those of a low-molecular-weight model ligand, i.e. the sodium salt of N-(4-methyl-2-oxo-1,2-dihydroquinolin-7-yl)succinamic acid (II). The long-lived emission intensities of Tb{sup 3+} at 490, 545, 585, and 620 nm corresponding to the {sup 5}D{sub 4}→{sup 7}F{sub 6}, {sup 5}D{sub 4}→{sup 7}F{sub 5}, {sup 5}D{sub 4}→{sup 7}F{sub 4}, and {sup 5}D{sub 4}→{sup 7}F{sub 3} transitions, respectively, were strongly increased by the addition of ligands in the order [II-Tb{sup 3+}]⪡[III-Tb{sup 3+}]<[IV-Tb{sup 3+}]. The efficiency of energy transfer (E) was evaluated from the emission intensity of the donor (Ω) in the presence or absence of the acceptor (Tb{sup 3+}) depending on the acceptor concentration and ligand neutralization. It was concluded that the macromolecular ligand structural properties (polymer coil and supramolecular structures, e.g. micelles) were responsible for the increase in RET. The time-resolved luminescence measurements revealed that the binding affinity of the ligands II, III, and IV increased in the order II

Thermodynamics of a post combustion hydrate-based carbon dioxide capture process

International Nuclear Information System (INIS)

Ben Attouche Sfaxi, I.

2011-07-01

Hydrates selectivity towards carbon dioxide is offering a promising route for carbon dioxide removal from flue gases. Hydrate-based CO 2 capture process could substitute amine facilities widely implemented in gas treatment plants but suffering from oxidative degradation problems and high energy demand. In the framework of this thesis, we focus on phase equilibria that are involved in such process. Experimental dissociation conditions for clathrate hydrates of carbon dioxide and nitrogen, in the presence of some promoting molecules (Tetrahydrofuran, Tetrabutyl ammonium bromide and Tetrabutyl ammonium Fluoride ) are reported in the experimental section of this work. The data generated in this work along with literature data are compared to the model predictions. The developed model is based on the Cubic Plus Association (CPA) equation of state (EoS) for fluid phases combined to the van der Waals and Platteeuw's theory for the hydrate phase. (author)

Solvent effects on the adsorption and self-organization of Mn12 on Au(111).

Science.gov (United States)

Pineider, Francesco; Mannini, Matteo; Sessoli, Roberta; Caneschi, Andrea; Barreca, Davide; Armelao, Lidia; Cornia, Andrea; Tondello, Eugenio; Gatteschi, Dante

2007-11-06

A sulfur-containing single molecule magnet, [Mn12O12(O2CC6H4SCH3)16(H2O)4], was assembled from solution on a Au(111) surface affording both submonolayer and monolayer coverages. The adsorbate morphology and the degree of coverage were inspected by scanning tunneling microscopy (STM), while X-ray photoelectron spectroscopy (XPS) allowed the determination of the chemical nature of the adsorbate on a qualitative and quantitative basis. The properties of the adsorbates were found to be strongly dependent on the solvent used to dissolve the magnetic complex. In particular, systems prepared from tetrahydrofuran solutions gave arrays of isolated and partially ordered clusters on the gold substrate, while samples prepared from dichloromethane exhibited a homogeneous monolayer coverage of the whole Au(111) surface. These findings are relevant to the optimization of magnetic addressing of single molecule magnets on surfaces.

Hydrogen-deuterium exchange of the anionic group 6B transition-metal hydrides. Convenient, in-situ-deuterium transfer reagents

International Nuclear Information System (INIS)

Gaus, P.L.; Kao, S.C.; Darensbourg, M.Y.; Arndt, L.W.

1984-01-01

The facile exchange of hydrogen for detuerium in the anionic group 6B carbonyl hydrides HM(CO) 4 L - (M = Cr, W; L = CO P(OMe) 3 ) has been studied in THF 4 (tetrahydrofuran) with CH 3 OD, D 2 O, and CH 3 CO 2 D. This has provided a synthesis of the deuterides, DM(CO) 4 L - , as well as a convenient in situ source of deuteride reducing reagents for organic halides. A number of such reductions are described, using 2 H NMR to demonstrate both selectivity and stereospecificity for certain systems. The carbonyl region of the infrared spectra of the hydrides is not affected by deuteration of the hydrides, suggesting that the M-H or M-D vibrational modes are not coupled significantly to CO vibrations in these hydrides. The mechanism of the H/D exchange and of a related H 2 elimination reaction is discussed

Electrical and spectroscopic characterization of polyaniline-polyvinyl chloride (PANI-PVC) blends doped with sodium thiosulphate

International Nuclear Information System (INIS)

Ameen, Sadia; Ali, Vazid; Zulfequar, M.; Mazharul Haq, M.; Husain, M.

2008-01-01

Polyaniline is doped with sodium thiosulphate in aqueous tetrahydrofuran (THF) and the blended films have been prepared by changing the amount of doped polyaniline (PANI) in the fixed amount of polyvinyl chloride (PVC). The electrical conductivity of various samples of polyaniline-polyvinyl chloride (PANI-PVC) blends has been studied to see the effect of dopant in the temperature range 300-400 K. Mott's parameters are used to explain the conduction mechanism. Different parameters such as pre-exponential factor (σ 0 ), activation energy (ΔE) and T 0 have also been calculated to see the effect of chemical doping. The crystallinity of the blends is explained on the basis of T 0 . The calculated values of T 0 show that crystallinity increases with an increase of doped PANI in PANI-PVC blends. Fourier transform-infrared (FTIR) spectroscopy is done to explore the nature and interaction of dopant into the polymeric chain

New methods for the evaluation and analysis of organoleptic qualities of foodstuffs and for the forecast of their changes. 9

International Nuclear Information System (INIS)

Herrmann, J.; Grigorova, St.; Grigorov, L.

1976-01-01

It has been found that the irradiation flavour is attributable to low-boiling substances which appear already in the first fraction if the modified MICKO distillation is performed. Tetrahydrofuran (THF) has been identified as the key substance in irradiation flavour. As further evidence may be quoted the similarity of the intensity of off-flavour which was observed also by gaschromatography at the same times of retention, and the removal of the irradiation flavour by means of a THF-specific agent (mercury acetate). The dependence of the intensity of irradiation flavour on the THF concentration and the gamma radiation dose, respectively, obeyed an exponential function. Thus, it has been possible to calculate the amounts of THF formed by radiation doses varying from 0.64 to 2.55 Mrad. The minimum radiation dose for 12% apple juice and 67% apple concentrate at which the irradiation flavour is first perceived was determined. (author)

Investigation on the effect of THF on Nitrogen Hydrate formation under isobaric condition

Science.gov (United States)

Jamil, N.; Husin, H.; Aman, Z.; Hassan, Z.

2018-03-01

In this paper, we studied nitrogen (N2) hydrate formation in the presence of tetrahydrofuran (THF) under 3 different conditions; different concentration of THF (0, 3 and 30 %(v/v), different temperature setting (room temperature and induced temperature) and different water content (15, 35 and 55 mL) in an isobaric condition. We found that in the presence of THF which acting as an enhancer, hydrate formation kinetic is highly influenced by these parameters. We observed a striking contrast in hydrate formation behaviour observed at room temperature (RT) and induced temperature (IT) with and without the presence of THF under similar operating conditions. At the presence of 30 %(v/v) of THF in 15 mL water, it can be seen that, hydrate tend to form faster than other samples. Visual observation of N2hydrates are also conducted at 30 %(v/v) of THF in 15 mL water.

Development and Characterization of Novel Polyurethane Films Impregnated with Tolfenamic Acid for Therapeutic Applications

Directory of Open Access Journals (Sweden)

Hilal Istanbullu

2013-01-01

Full Text Available The present study deals with the preparation of polyurethane (PU films impregnated with a nonsteroidal anti-inflammatory drug, tolfenamic acid (TA. Solvent evaporation technique has been employed for the preparation of TA-PU films in two different ratios of 1 : 2 and 1 : 5 in Tetrahydrofuran (THF or THF-ethanol mixtures. The prepared films were characterized using X-Ray Diffraction (XRD, Differential Scanning Calorimetry (DSC, Fourier Transform Infrared Spectroscopy (FTIR, Scanning Electron Microscopy (SEM, and release studies. The results indicate transformation of crystalline TA to its amorphous form. The degree of crystallinity changes both by increasing the polymer concentration and solvent used for the film preparations. The release profiles of TA were also found to be affected, showing a decrease from approximately 50% to 25% from 1 : 2 to 1 : 5 ratios, respectively.

Novel method for quantitative estimation of biofilms

DEFF Research Database (Denmark)

Syal, Kirtimaan

2017-01-01

Biofilm protects bacteria from stress and hostile environment. Crystal violet (CV) assay is the most popular method for biofilm determination adopted by different laboratories so far. However, biofilm layer formed at the liquid-air interphase known as pellicle is extremely sensitive to its washing...... and staining steps. Early phase biofilms are also prone to damage by the latter steps. In bacteria like mycobacteria, biofilm formation occurs largely at the liquid-air interphase which is susceptible to loss. In the proposed protocol, loss of such biofilm layer was prevented. In place of inverting...... and discarding the media which can lead to the loss of the aerobic biofilm layer in CV assay, media was removed from the formed biofilm with the help of a syringe and biofilm layer was allowed to dry. The staining and washing steps were avoided, and an organic solvent-tetrahydrofuran (THF) was deployed...

Evaluation of dosimetric characteristics of graphene oxide/PVC nanocomposite for gamma radiation applications

Energy Technology Data Exchange (ETDEWEB)

Feizi, Shahzad; Malekie, Shahryar; Ziaie, Farhood [Nuclear Science and Technology Research Institute (NSTRI), Karaj (Iran, Islamic Republic of). Radiation Application Research School; Rahighi, Reza; Tayyebi, Ahmad [Univ. of Technology, Tehran (Iran, Islamic Republic of). Dept. of Physics

2017-04-01

Graphene oxide-polyvinyl chloride composite was prepared using tetrahydrofuran solvent-assisted dispersion of characterized nano flakes of graphene oxide in polymer matrix. Electrical percolation threshold of GO/PVC nanocomposite was determined via a finite element simulation method with a 2D model and compared with experimental results. A conductive cell with two silver coated walls was designed and fabricated for exploring dosimetric properties of the composite. Some characteristics of the new nanocomposite such as linearity of dose response, repeatability, sensitivity and angular dependence are investigated. According to 2D proposed method, obtained data associated to electrical conductivity of the GO/polymer composite for PVC matrix plotted in different GO weight percentages and had good compatibility (validity) with experimental data. The dose response is linear in the 17-51 mGy dose range and it can be introduced for gamma radiation dosimetry in diagnostic activities.

Effects of dope extrusion rate on the morphology and gas separation performance of asymmetric polysulfone hollow fiber membranes for O2/N2 separation

Directory of Open Access Journals (Sweden)

Ahmad Fausi Ismail

2002-11-01

Full Text Available The objective of this study was to investigate the influence of dope extrusion rates on morphology and gas separation performance of asymmetric polysulfone hollow fiber membranes. Asymmetric polysulfone hollow fiber membranes for gas separation were prepared from a solution consisting of 26.0 wt. % of polysulfone, 30.4 wt. % of N, N-dimethylacetamide, 30.4 wt. % of tetrahydrofuran and 13.2 wt. % ethanol. The dry/wet phase separation process was applied to a dry/wet spinning process. Fibers were spun at various dope extrusion rates (DER ranging from 1.5 - 3.0 cm3/min and hence at different levels of shear. The results suggest that as the dope extrusion rate is increased, the selectivity will increase until a critical level of shear is reached, beyond which the membrane performance deteriorates. Pressure-normalized-fluxes and selectivities were evaluated by using pure oxygen and nitrogen as test gases.

Photophysical, Photochemical, and BQ Quenching Properties of Zinc Phthalocyanines with Fused or Interrupted Extended Conjugation

Directory of Open Access Journals (Sweden)

Gülşah Gümrükçü

2014-01-01

Full Text Available The effects of substituents and solvents on the photophysical and photochemical parameters of zinc(II phthalocyanines containing four Schiff’s base substituents attached directly and through phenyleneoxy-bridges on peripheral positions are reported. The group effects on peripheral position and the continual and intermittent conjugation of the phthalocyanine molecules on the photophysical and photochemical properties are also investigated. General trends are described for photodegradation, singlet oxygen, and fluorescence quantum yields of these compounds in dimethylsulfoxide (DMSO, dimethylformamide (DMF, and tetrahydrofurane (THF. Among the different substituents, phthalocyanines with cinnamaldimine moieties (1c and 2c have the highest singlet oxygen quantum yields (ΦΔ and those with nitro groups (1a and 2a have the highest fluorescence quantum yields in all the solvents used. The fluorescence of the substituted zinc(II phthalocyanine complexes is effectively quenched by 1,4-benzoquinone (BQ in these solvents.

Studies of the analytical and preparatory separation of the lanthanide series by means of high-pressure-liquid-chromatography

International Nuclear Information System (INIS)

Weuster, W.

1980-01-01

With the Elution-system di-iso-propylether/tetrahydrofurane/di-(2-ethylhexyl)-phosphate/nitric acid all lanthanide series elements can be separated. To optimize the separation, these reactions are studied as a function of sorbent, composition, velocity and temperature of eluting agents. The rare earth elements are detected by observation of the extinguishing fluorescence, excited at a wavelength of 240 nm, with a detection limit of 2.5 μg rare earth material per ml of eluate. The method has been used for the determination of rare earth concentrations in minerals and technical products, for chemical separation of rare earths (i.e. Eu/Gd in mg quantities with a 1:10 quantity ratio) and for the separation of rare earth elements from uranium and fission products. In addition the possibility of isotope enrichment has been demonstrated in the case of 144 Sm/ 154 Sm. (DG) [de

Investigation of static and dynamic wetting transitions of UV responsive tunable wetting surfaces

International Nuclear Information System (INIS)

Pant, Reeta; Singha, Subhash; Bandyopadhyay, Aritra; Khare, Krishnacharya

2014-01-01

Ultraviolet (UV) radiation responsive surfaces, with tunable wetting properties, are fabricated by spin casting polystyrene/titania nanocomposite dispersion in tetrahydrofuran on silicon substrates. The prepared samples are found hydrophilic due to the presence of the water miscible solvent. Upon annealing, as the solvent evaporates, samples become superhydrophobic due to presence of hydrophobic polystyrene and formation of nano and micro scale surface roughness due to titania nanoparticles. Effect of different annealing temperatures and time on resulting wettability is investigated. Photocatalytic property of titania is exploited to make transition from superhydrophobic to hydrophilic state upon UV exposure. Subsequently, upon annealing again at elevated temperatures for sufficient time, the UV exposed hydrophilic samples recover their superhydrophobicity showing transition from hydrophilic to superhydrophobic state. Detailed static and dynamic study of these reversible transitions, between superhydrophobic and hydrophilic states, due to UV exposure and annealing is presented in this article.

The intake of carotenoids in Denmark

DEFF Research Database (Denmark)

Leth, Torben; Jakobsen, Jette; Andersen, N. L.

2000-01-01

To estimate the intake of carotenoids in the Danish population Danish fruits and vegetables were screened with an HPLC method consisting of extraction with ethanol:tetrahydrofuran, separation by reversed phase HPLC with the mobile phase acetonitril:methanol:dichlormethan, triethylamin, BHT...... in the foods the mean intake and intake distribution of the carotenoids were calculated. Carrots and tomatoes have both high contents of carotenoids (8,450 mu g/100 g alpha- + beta-carotene and 4,790 mu g/100 g lycopene, respectively) and high intakes (19 and 15 g/day, respectively) and were responsible for 47......% and 32%, respectively, of the mean intake of carotenoids of 4.8 mg/day A median value of 4.1 mg/day was found indicating skewed intake distributions. The difference between men and women was 0.4 mg/day (p carotenoids, alpha-carotene, beta-carotene, lutein and lycopene, contributed...

Metathesis Polymerization Reactions Induced by the Bimetallic Complex (Ph4P2[W2(μ-Br3Br6

Directory of Open Access Journals (Sweden)

Despoina Chriti

2015-12-01

Full Text Available The reactivity of the bimetallic complex (Ph4P2[W2(μ-Br3Br6] ({W 2.5 W}7+, a′2e3 towards ring opening metathesis polymerization (ROMP of norbornene (NBE and some of its derivatives, as well as the mechanistically related metathesis polymerization of phenylacetylene (PA, is presented. Our results show that addition of a silver salt (AgBF4 is necessary for the activation of the ditungsten complex. Polymerization of PA proceeds smoothly in tetrahydrofuran (THF producing polyphenylacetylene (PPA in high yields. On the other hand, the ROMP of NBE and its derivatives is more efficient in CH2Cl2, providing high yields of polymers. 13C Cross Polarization Magic Angle Spinning (CPMAS spectra of insoluble polynorbornadiene (PNBD and polydicyclopentadiene (PDCPD revealed the operation of two mechanisms (metathetic and radical for cross-linking, with the metathesis pathway prevailing.

(Liquid + liquid) equilibria of binary systems containing hyperbranched polymer Boltorn (registered) H2004 - Experimental study and modelling in terms of lattice-cluster theory

International Nuclear Information System (INIS)

Domanska, Urszula; Paduszynski, Kamil; Zolek-Tryznowska, Zuzanna

2011-01-01

(Liquid + liquid) phase equilibria (LLE) of binary mixtures containing hyperbranched polymer Boltorn (registered) H2004 and n-alkanes (n-hexane, n-heptane, n-octane, and n-decane) were studied over the temperature range from about (260 up to 360) K. The polymer is partially miscible with n-alkanes and the solubility decreases with an increase of the chain length of the solvent. Corresponding LLE phase diagrams including spinodal and binodal (liquid + liquid) coexistence curves were calculated in terms of the statistical mechanics - based on the lattice-cluster theory, based only on the upper critical solution temperature, and the polymer chain architecture. The results show semi-qualitative agreement of predicted and experimental equilibrium compositions and temperatures. Boltorn (registered) H2004 reveals complete miscibility in the liquid phase with alcohols (C 1 -C 8 ), aromatic hydrocarbons (benzene, toluene, and thiophene), and ethers (methyl tetra-butyl ether, ethyl tetra-butyl ether, and tetrahydrofurane).

The use of galactose oxidase in lipid labeling

International Nuclear Information System (INIS)

Radin, N.S.; Evangelatos, G.P.

1981-01-01

Galactose oxidase can be used to oxidize the terminal carbon atom of lipids containing galactose or N-acetylgalactosamine, and the resultant aldehyde group can be reduced back to the original carbinol with radioactive borohydride. The efficiency of the first reaction has been investigated systematically by using [6- 3 H]galactosyl ceramide as substrate and measuring the amount of radioactive water formed. This enabled us to establish that the addition of catalase and peroxidase greatly speeded the oxidation, that phosphate and PIPES buffers were the best among those tested, that the reaction continued for 24 hr without a second addition of galactose oxidase, and that the optimum concentration of organic solvent (tetrahydrofuran) was 50%. The suggestion if made that a similar set of variables be studied for each lipid or nonlipid by the same basic technique: labeling by the oxidase/borohydride method and use of the resultant compound as substrate

Computing the Absorption and Emission Spectra of 5-Methylcytidine in Different Solvents: A Test-Case for Different Solvation Models.

Science.gov (United States)

Martínez-Fernández, L; Pepino, A J; Segarra-Martí, J; Banyasz, A; Garavelli, M; Improta, R

2016-09-13

The optical spectra of 5-methylcytidine in three different solvents (tetrahydrofuran, acetonitrile, and water) is measured, showing that both the absorption and the emission maximum in water are significantly blue-shifted (0.08 eV). The absorption spectra are simulated based on CAM-B3LYP/TD-DFT calculations but including solvent effects with three different approaches: (i) a hybrid implicit/explicit full quantum mechanical approach, (ii) a mixed QM/MM static approach, and (iii) a QM/MM method exploiting the structures issuing from molecular dynamics classical simulations. Ab-initio Molecular dynamics simulations based on CAM-B3LYP functionals have also been performed. The adopted approaches all reproduce the main features of the experimental spectra, giving insights on the chemical-physical effects responsible for the solvent shifts in the spectra of 5-methylcytidine and providing the basis for discussing advantages and limitations of the adopted solvation models.

Photochemistry of 2,2',4,4',5,5'-hexabde (BDE-153) in THF and adsorbed on SiO2: first observation of OH reactivity of BDEs on aerosol

Energy Technology Data Exchange (ETDEWEB)

Zetzsch, C.; Krueger, H.U. [Forschungsstelle Atmosphaerische Chemie, Univ. Bayreuth (Germany); Palm, W.U. [Inst. fuer Oekologie und Umweltchemie, Univ. Lueneburg (Germany)

2004-09-15

BDE-153 (2,2',4,4',5,5'-hexabromo diphenylether) is a component of the flame retardant mixtures penta- and octaBDE and a trace constituent of decaBDE. Furthermore, it may occur as a minor intermediate in the photolysis of decaBDE. We have previously studied the UV spectrum and quantum yield for the photolysis of BDE-153 in tetrahydrofuran (THF) solution3, and we now present a comparison of the photolytic degradation pathways of this symmetrical molecule in solution and adsorbed at sub-monlayer thickness on aerosol particles, made of fused silica (Aerosil 380), in an aerosol smog chamber facility. Furthermore, the aerosol smog chamber technique allows us to expose aerosol-borne compounds to OH radicals, which are known to clean the atmosphere efficiently from air pollutants. Atmospheric residence times of air pollutants can then be assessed from the rate constants for the reaction with OH radicals, and a first, preliminary result on BDE-153 + OH will be presented.

Six cytotoxic annonaceous acetogenins from Annona squamosa seeds.

Science.gov (United States)

Chen, Yong; Chen, Jian-Wei; Wang, Yu; Xu, Sha-Sha; Li, Xiang

2012-12-01

Custard apple (Annona squamosa L.) is an edible tropical fruit, and its seeds had been used in south China as a folk medicine to treat "malignant sore" (cancer) and as an insecticide. Phytochemical investigation of the ethanol fraction of custard apple seeds led to the isolation of six new annonaceous acetogenins: annosquacins A-D (1-4), annosquatin A (5) and annosquatin B (6). Their structures were elucidated by spectroscopic analysis. Compounds 1-4 are adjacent bistetrahydrofuran annonaceous acetogenins. Compounds 5 and 6 are non-adjacent bistetrahydrofuran annonaceous acetogenins and the first examples in which the tetrahydrofuran ring system is located between C-9 and C-20. The absolute configurations of 1-6 were defined by the application of the Mosher method. Compounds 1-6 exhibited potent cytotoxic activity in vitro against five human tumour cell lines. Compounds 5 and 6 showed a high selectivity toward the MCF-7 and A-549 cell line respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

Syntheses of cytotoxic novel arctigenin derivatives bearing halogen and alkyl groups on aromatic rings.

Science.gov (United States)

Yamauchi, Satoshi; Wukirsari, Tuti; Ochi, Yoshiaki; Nishiwaki, Hisashi; Nishi, Kosuke; Sugahara, Takuya; Akiyama, Koichi; Kishida, Taro

2017-09-01

The new lignano-9,9'-lactones (α,β-dibenzyl-γ-butyrolactone lignans), which showed the higher cytotoxicity than arctigenin, were synthesized. The well-known cytotoxic arctigenin showed activity against HL-60 cells (EC 50 =12μM), however, it was inactive against HeLa cells (EC 50 >100μM). The synthesized (3,4-dichloro, 2'-butoxy)-derivative 55 and (3,4-dichloro, 4'-butyl)-derivative 66 bearing the lignano-9,9'-lactone structures showed the EC 50 values of 10μM and 9.4μM against HL-60 cells, respectively. Against HeLa cells, the EC 50 value of the derivative 66 was 27μM. By comparing the activities with the corresponding 9,9'-epoxy structure (tetrahydrofuran compounds), the importance of the lactone structure of 55 and 66 for the higher activities was shown. The substituents on the aromatic ring of the lignano-9,9'-lactones affected the cytotoxicity level, observing more than 10-fold difference. Copyright © 2017. Published by Elsevier Ltd.

Manipulating the Morphology of P3HT–PCBM Bulk Heterojunction Blends with Solvent Vapor Annealing

KAUST Repository

Verploegen, Eric; Miller, Chad E.; Schmidt, Kristin; Bao, Zhenan; Toney, Michael F.

2012-01-01

Using grazing incidence X-ray scattering, we observe the effects of solvent vapors upon the morphology of poly(3-hexylthiophene)-phenyl-C 61-butyric acid methyl ester (P3HT-PCBM) bulk heterojunction thin film blends in real time; allowing us to observe morphological rearrangements that occur during this process as a function of solvent. We detail the swelling of the P3HT crystallites upon the introduction of solvent and the resulting changes in the P3HT crystallite morphology. We also demonstrate the ability for tetrahydrofuran vapor to induce crystallinity in PCBM domains. Additionally, we measure the nanoscale phase segregated domain size as a function of solvent vapor annealing and correlate this to the changes observed in the crystallite morphology of each component. Finally, we discuss the implications of the morphological changes induced by solvent vapor annealing on the device properties of BHJ solar cells. © 2012 American Chemical Society.

Assay of common sunscreen agents in suncare products by high-performance liquid chromatography on a cyanopropyl-bonded silica column.

Science.gov (United States)

Simeoni, Silvia; Tursilli, Rosanna; Bianchi, Anna; Scalia, Santo

2005-06-15

A rapid high-performance liquid chromatographic method was developed for the simultaneous assay of eight of the most common sunscreen agents (octyl-methoxycinnamate, oxybenzone, butyl-methoxydibenzoylmethane, octyl-salicilate, methylbenzylidene camphor, octyl-dimethylamminobenzoate, phenylbenzimidazole sulphonic acid and octocrylene) in sun protection products. Evaluation of the influence of different stationary phases and eluents on the separation selectivity showed that optimal resolution was obtained on a cyanopropyl-silica column eluted with methanol-acetonitrile-tetrahydrofuran-aqueous acetic acid. A small adjustment of the proposed chromatographic system (reduction in the aqueous content of the mobile phase) permitted also the determination of the extremely hydrophobic UV filter, methylene bis-benzotriazolyl tetramethylbutylphenol along with three other sunscreen agents, octyl-methoxycinnamate, oxybenzone, butyl-methoxydibenzoylmethane. Recoveries of the UV filters from the spiked formulation were between 95.7 and 103.7% and the precision of the method was better than 6.1% relative standard deviation. The developed HPLC procedure is suitable for quality control and photostability analyses of commercial suncare products.

Organic chemicals in the environment

International Nuclear Information System (INIS)

Anderson, T.A.; Beauchamp, J.J.; Walton, B.T.

1991-01-01

Disappearance of 15 volatile and semivolatile organic compounds was determined in a mixture added to two different soil types using experimental procedures to distinguish abiotic losses from biological degradation over a 7-d period. Losses due to volatilization were quantified and mass balances were calculated for each compound. The compounds (methyl ethyl ketone; tetrahydrofuran; chlorobenzene; benzene; chloroform; carbon tetrachloride; p-xylene; 1,2-dichlorobenzene; cis-1,4-dich-loro-2-butene; 1,2,3-trichloropropane; 2-chloronaphthalene; ethylene dibromide; hexachlorobenzene; nitrobenzene; and toluene) were applied to the soil in a mixture such that the concentration of each chemical was 100 mg/kg soil (dry wt.). Apparent half-lives for the 15 organic compounds ranged from 14 C-toluene, were unsuccessful. Nonreversible sorption and preanalysis storage conditions were considered as contributors to this inability to achieve a mass balance. On the basis of these results, the authors strongly advise positive accounting for all test compounds and degradation products at the conclusion of studies involving volatile and semivolatile compounds

Synthesis, photophysical and photochemical properties of zinc phthalocyanines bearing fluoro-functionalized substituents

International Nuclear Information System (INIS)

Aktaş, Ayşe; Pişkin, Mehmet; Durmuş, Mahmut; Bıyıklıoğlu, Zekeriya

2014-01-01

In this study, the synthesis of phthalonitrile derivatives bearing fluoro-functionalized groups and their peripherally-tetra substituted zinc phthalocyanine complexes were reported. The phthalonitrile derivatives 2a–5a were prepared by nucleophilic substitution of 4-nitrophthalonitrile with 2-[3-(trifluoromethyl)phenoxy]ethanol, 2-{2-[3-(trifluoromethyl) phenoxy]ethoxy}ethanol, 2-(2,3,5,6-tetrafluorophenoxy)ethanol, 2-[2-(2,3,5,6-tetrafluorophenoxy)ethoxy]ethanol, respectively. Zinc phthalocyanines bearing fluoro-functionalized groups (2b–5b) were obtained from the corresponding phthalonitrile derivatives. The newly synthesized phthalocyanines displayed good solubility in organic solvents such as chloroform (CHCl 3 ), dichloromethane (DCM), tetrahydrofuran (THF), toluene, dimethylformamide (DMF) and dimethylsulfoxide (DMSO). On the other hand, the singlet oxygen, photodegradation, fluorescence quantum yields and fluorescence lifetime of these complexes were determined in DMSO. The effects of the substitution with fluoro-functionalized groups on these parameters were also compared. -- Highlights: • Synthesis of peripherally substituted zinc phthalocyanines. • Photophysical and photochemical properties in DMSO for phthalocyanines. • Photodynamic therapy studies

Thin-film composite crosslinked polythiosemicarbazide membranes for organic solvent nanofiltration (OSN)

KAUST Repository

Aburabie, Jamaliah

2015-01-01

In this work we report a new class of solvent stable thin-film composite (TFC) membrane fabricated on crosslinked polythiosemicarbazide (PTSC) as substrate that exhibits superior stability compared with other solvent stable polymeric membranes reported up to now. Integrally skinned asymmetric PTSC membranes were prepared by the phase inversion process and crosslinked with an aromatic bifunctional crosslinker to improve the solvent stability. TFC membranes were obtained via interfacial polymerization using trimesoyl chloride (TMC) and diaminopiperazine (DAP) monomers. The membranes were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and contact angle measurement.The membranes exhibited high fluxes toward solvents like tetrahydrofuran (THF), dimethylformamide (DMF) and dimethylsulfoxide (DMSO) ranging around 20L/m2 h at 5bar with a molecular weight cut off (MWCO) of around 1000g/mol. The PTSC-based thin-film composite membranes are very stable toward polar aprotic solvents and they have potential applications in the petrochemical and pharmaceutical industry.

Reactive phase inversion for manufacture of asymmetric poly (ether imide sulfone) membranes

KAUST Repository

Jalal, Taghreed; Charry Prada, Iran David; Tayouo Djinsu, Russell; Giannelis, Emmanuel P.; Nunes, Suzana Pereira

2014-01-01

Poly (ether imide sulfone) membranes were manufactured by combining phase inversion and functionalization reaction between epoxy groups and amine modified polyether oligomers (Jeffamine) or TiO2 nanoparticles. Polysilsesquioxanes containing epoxy functionalities were in-situ grown in the casting solution and made available for further reaction with amines in the coagulation/annealing baths. The membranes were characterized by field emission scanning electron microscopy, porosimetry and water flux measurements. Water permeances up to 1500 l m-2 h-1 bar-1 were obtained with sharp pore size distribution and a pore diameter peak at 66 nm, confirmed by porosimetry, which allowed 99.2% rejection of γ-globulin. Water flux recovery of 77.5% was achieved after filtration with proteins. The membranes were stable in 50:50 dimethylformamide/water, 50:50 N-methyl pyrrolidone/water and 100% tetrahydrofuran. The possibility of using similar concept for homogeneous and stable attachment of nanoparticles on the membrane surface was demonstrated.

Spectral characterization of a newly synthesized fluorescent semicarbazone derivative and its usage as a selective fiber optic sensor for copper(II).

Science.gov (United States)

Oter, Ozlem; Ertekin, Kadriye; Kirilmis, Cumhur; Koca, Murat

2007-02-19

In this work photoluminescent properties of highly Cu(2+) selective organic fluoroionophore, semicarbazone derivative; bis(naphtho[2,1-b]furan-2-yl)methanone semicarbazone (BNF) was investigated in different solvents (dichloromethane, tetrahydrofuran, toluene and ethanol) and in polymer matrices of polyvinylchloride (PVC) and ethyl cellulose (EC) by absorption and emission spectrometry. The BNF derivative displayed enhanced fluorescence emission quantum yield, Q(f)=6.1 x 10(-2) and molar extinction coefficient, epsilon=29,000+/-65 cm(-1)M(-1) in immobilized PVC matrix, compared to 2.6 x 10(-3) and 24,573+/-115 in ethanol solution. The offered sensor exhibited remarkable fluorescence intensity quenching upon exposure to Cu(2+) ions at pH 4.0 in the concentration range of 1.0 x 10(-9) to 3.0 x 10(-4)M [Cu(2+)] while the effects of the responding ions (Ca(2+), Hg(+), Pb(2+), Al(3+), Cr(3+), Mn(2+), Mg(2+), Sn(2+), Cd(2+), Co(2+) and Ni(2+)) were less pronounced.

Synthesis, photophysical and photochemical properties of zinc phthalocyanines bearing fluoro-functionalized substituents

Energy Technology Data Exchange (ETDEWEB)

Aktaş, Ayşe [Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey); Pişkin, Mehmet [Marmara University, Faculty of Art and Science, Department of Chemistry, 34722 Kadikoy-Istanbul (Turkey); Durmuş, Mahmut [Gebze Institute of Technology, Department of Chemistry, PO Box 141, Gebze 41400, Kocaeli (Turkey); Bıyıklıoğlu, Zekeriya, E-mail: zekeriya_61@yahoo.com [Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey)

2014-01-15

In this study, the synthesis of phthalonitrile derivatives bearing fluoro-functionalized groups and their peripherally-tetra substituted zinc phthalocyanine complexes were reported. The phthalonitrile derivatives 2a–5a were prepared by nucleophilic substitution of 4-nitrophthalonitrile with 2-[3-(trifluoromethyl)phenoxy]ethanol, 2-{2-[3-(trifluoromethyl) phenoxy]ethoxy}ethanol, 2-(2,3,5,6-tetrafluorophenoxy)ethanol, 2-[2-(2,3,5,6-tetrafluorophenoxy)ethoxy]ethanol, respectively. Zinc phthalocyanines bearing fluoro-functionalized groups (2b–5b) were obtained from the corresponding phthalonitrile derivatives. The newly synthesized phthalocyanines displayed good solubility in organic solvents such as chloroform (CHCl{sub 3}), dichloromethane (DCM), tetrahydrofuran (THF), toluene, dimethylformamide (DMF) and dimethylsulfoxide (DMSO). On the other hand, the singlet oxygen, photodegradation, fluorescence quantum yields and fluorescence lifetime of these complexes were determined in DMSO. The effects of the substitution with fluoro-functionalized groups on these parameters were also compared. -- Highlights: • Synthesis of peripherally substituted zinc phthalocyanines. • Photophysical and photochemical properties in DMSO for phthalocyanines. • Photodynamic therapy studies.

Novel cleavage and oligomerization reactions of nickel (o) complexes. Application to homogeneous deoxygenation and desulfurization

International Nuclear Information System (INIS)

Eisch, J.J.; Im, K.R.

1979-01-01

The ease of interaction of Ni(0) complexes with organic substrates has been shown to depend upon both the ligands on nickel and the solvent. The presence of α,α'-bipyridyl with the Ni(0) complex and the alkyne led to the isolation of a nickelacyclopropene, an observation in accord with the recently proposed metallocyclic pathway for the Ni(0)-catalyzed trimerization of alkynes. Allylic and benzylic ethers and epoxides have been observed to undergo oxidative insertion of Ni(0) into their C-O bonds with solvent (TMEDA > THF (tetrahydrofuran) > Et 2 O > C 6 H 6 ) and ligand (Et 3 P (tripthyl phosphine) > Ph 3 P (triphenyl phosphine); α,α'-bipy > COD) effects consistent with an electron-transfer attack by Ni(0). With such sulfur heterocycles as dibenzothiophene, phenoxathiin, phenothiazine, and thianthrene, a 1:1 admixture of (COD) 2 Ni with α,α'-bipyridyl gave as the principal product the desulfurized, ring-contracted cyclic product

Liquid chromatographic determination with fluorescence detection of B6 vitamers and riboflavin in milk and pharmaceuticals

International Nuclear Information System (INIS)

Gatti, R.; Gioia, M.G.

2005-01-01

A simple, reliable and selective high performance liquid chromatographic method with fluorescence detection at different programmed wavelengths has been developed for the simultaneous analysis of B 6 vitamers (pyridoxal 5'-phosphate, 4-pyridoxic acid, pyridoxal, pyridoxine and pyridoxamine) and Vitamin B 2 in commercial vitaminized milk and in woman milk. The chromatographic separations were performed on a reversed phase octyl column by using a mobile phase consisting of sodium pentanesulfonate in 1% acetic acid-methanol-tetrahydrofuran under gradient elution conditions. The fluorescence intensity of pyridoxal 5'-phosphate was enhanced by post-column photochemical conversion, giving significantly different fluorescence spectra by a on-line photoreactor switched OFF and ON under irradiation at 254 nm. In addition, a simple and rapid method in isocratic conditions without the need of photochemical conversion was proposed for the analysis of Vitamin B 6 and Vitamin B 2 in pharmaceuticals. Linearity, precision, recovery, selectivity and sensitivity were found satisfactory for each analysed compound. Quantitation limits ranged from 26 to 240 fmol

Solubilization of meso-carbon microbeads by potassium- or dibutylzinc-promoted butylation and structural analysis of the butylated products; Mesocarbon microbeads no butyl ka ni yoru kayoka to erareta butyl kabutsu no kozo kaiseki

Energy Technology Data Exchange (ETDEWEB)

Murata, S.; Zhang, Y.; Kidena, K.; Nomura, M. [Osaka University, Osaka (Japan). Faculty of Engineering

1996-10-28

Tetrahydrofuran (THF) solubility and structure of the butylated products of meso-carbon microbeads (MCMB) were studied experimentally. In experiment, MCMB-A and MCMB-B obtained from two kinds of coal-tar pitch were used as specimens. MCMBs were butylated by BZ method using dibutylzinc-butyl iodide and KT method using K-butyl iodide-THF, and the butylated products were successfully obtained. The butylated products were investigated through THF solubility test, {sup 13}C-NMR measurement and gel permeation chromatography (GPC) measurement. As the experimental result, a BZ method produced the butylated products at a yield of nearly 170%, while a KT method produced them at a yield of nearly 130%. The THF solubility was estimated to be 89-97%. As the study result of molecular weight distributions by GPC measurement of solvent solubles, the molecular weight of raw material MCMB was estimated to be 590-770 in terms of polystyrene. 6 refs., 2 figs., 1 tab.

Field Emission Property of Double-walled Carbon Nanotubes Related to Purification and Transmittance

International Nuclear Information System (INIS)

Ahn, KiTae; Jang, HyunChul; Hong, Wanshick; Park, Kyoungwan; Sok, Junghyun; Lyu, SeungChul; Lee, Hansung; Lee, Naesung; Han, Moonsup; Park, Yunsun

2011-01-01

Double-walled carbon nanotubes (DWCNTs) with high purity were produced by the catalytic decomposition of tetrahydrofuran (THF) using a Fe-Mo/MgO catalyst at 800°C. The as-synthesized DWCNTs typically have catalytic impurities and amorphous carbon, which were removed by a two-step purification process consisting of acid treatment and oxidation. In the acid treatment, metallic catalysts were removed in HCl at room temperature for 5 hr with magnetic stirring. Subsequently, the oxidation, using air at 380°C for 5 hr in the a vertical-type furnace, was used to remove the amorphous carbon particles. The DWCNT suspension was prepared by dispersing the purified DWCNTs in the aqueous sodium dodecyl sulfate solution with horn-type sonication. This was then air-sprayed on ITO glass to fabricate DWCNT field emitters. The field emission properties of DWCNT films related to transmittance were studied. This study provides the possibility of the application of large-area transparent CNT field emission cathodes.

Glycyrrhiza glabra (Linn.) and Lavandula officinalis (L.) cell suspension cultures-based biotransformation of β-artemether.

Science.gov (United States)

Patel, Suman; Gaur, Rashmi; Upadhyaya, Mohita; Mathur, Archana; Mathur, Ajay K; Bhakuni, Rajendra S

2011-07-01

The biotransformation of β-artemether (1) by cell suspension cultures of Glycyrrhiza glabra and Lavandula officinalis is reported here for the first time. The major biotransformed product appeared as a grayish-blue color spot on thin-layer chromatography (TLC) with transparent crystal-like texture. Based on its infrared (IR) and (1)H nuclear magnetic resonance (NMR) spectra, the product was characterized as a tetrahydrofuran (THF)-acetate derivative (2). The highest conversion efficiencies of 57 and 60% were obtained when 8-9-day-old cell suspensions of G. glabra and L. officinalis were respectively fed with 4-7 mg of compound 1 in 40 ml of medium per culture and the cells were harvested after 2-5 days of incubation. The addition of compound 1 at the beginning of the culture cycle caused severe growth depression in a dose-dependent manner, resulting in poor bioconversion efficiency of ~25% at 2-5 mg/culture dose only.

Electrocatalytic properties of carbon-supported Pt-Ru catalysts with the high alloying degree for formic acid electrooxidation

Energy Technology Data Exchange (ETDEWEB)

Chen, Yu.; Zhou, Yiming; Tang, Yawen; Lu, Tianhong [College of Chemistry and Environmental Science, Nanjing Normal University, Nanjing 210097 (China)

2010-07-01

A series of carbon-supported bimetallic Pt-Ru catalysts with high alloying degree and different Pt/Ru atomic ratio have been prepared by a chemical reduction method in the H{sub 2}O/ethanol/tetrahydrofuran (THF) mixture solvent. The structural and electronic properties of catalysts are characterized using X-ray reflection (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM). The electrooxidation of formic acid on these Pt-Ru nanoparticles are investigated by using cyclic voltammetry, chronoamperometry and CO-stripping measurements. The results of electrochemical measurements illustrate that the alloying degree and Pt/Ru atomic ratio of Pt-Ru catalyst play an important role in the electrocatalytic activity of the Pt-Ru/C catalyst for formic acid electrooxidation due to the bifunctional mechanism and the electronic effect. Since formic acid is an intermediate in the methanol electrooxidation on Pt electrode in acidic electrolyte, the observation provides an additional fundamental understanding of the structure-activity relationship of Pt-Ru catalyst for methanol electrooxidation. (author)

Hydroperoxide Traces in Common Cyclic Ethers as Initiators for Controlled RAFT Polymerizations.

Science.gov (United States)

Eggers, Steffen; Abetz, Volker

2018-04-01

Herein, a reversible addition-fragmentation chain transfer (RAFT) polymerization is introduced for reactive monomers like N-acryloylpyrrolidine or N,N-dimethylacrylamide working without a conventional radical initiator. As a very straightforward proof of principle, the method takes advantage of the usually inconvenient radical-generating hydroperoxide contaminations in cyclic ethers like tetrahydrofuran or 1,4-dioxane, which are very common solvents in polymer sciences. The polymerizations are surprisingly well controlled and the polymers can be extended with a second block, indicating their high livingness. "Solvent-initiated" RAFT polymerizations hence prove to be a feasible access to tailored materials with minimal experimental effort and standard laboratory equipment, only requiring the following ingredients: hydroperoxide-contaminated solvent, monomer, and RAFT agent. In other respects, however, the potential coinitiating ability of the used solvent is to be considered when investigating the kinetics of RAFT polymerizations or aiming for the synthesis of high-livingness polymers, e.g., multiblock copolymers. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Growth response of microorganisms to different molecular fractions of lignite

Energy Technology Data Exchange (ETDEWEB)

Polman, J.K.; Breckenridge, C.R.; Dugan, P.R.; Quigley, D.R.

1990-01-01

Our research is primarily concerned with isolating and characterizing microbes which are able to dissimilate coal and convert it to other useful chemicals. This quarter, general growth responses of microorganisms cultivated in the presence of different molecular weight fractions of lignite coal were examined. Aerobic and anaerobic environmental samples from a variety of ecological niches were used as inocula. Growth of the microorganisms in these samples on the following types of media was tested: COAL medium, containing alkali-solubilized whole coal; THFI medium, containing the alkali-solubilized, tetrahydrofuran-insoluble, macromolecular portion of whole coal; THFS medium, containing the THF-soluble, low molecular weight portion of whole coal; and CON medium, void of any coal constituent. Overall results indicated that the presence of the THF-soluble, low molecular weight coal fraction enhanced the growth yield and the variety of aerobic microorganisms compared to the other coal fractions or the control medium. Conversely, anaerobic microbes grew best on media which contained the macromolecular fraction. 12 refs., 5 tabs.

Bis{bis[1-methoxy-2-(2-methoxyethoxyethane-κ3O,O′,O′′]sodium} 1,1,2,2-tetraphenylethane-1,2-diide

Directory of Open Access Journals (Sweden)

Mikhail E. Minyaev

2014-07-01

Full Text Available Crystals of the title salt, [Na(C6H14O32]2(C26H20, were grown from a tetrahydrofuran/diglyme/Et2O solvent mixture [diglyme is 1-methoxy-2-(2-methoxyethoxyethane]. The cations and dianion are separated in the crystal structure, unlike in the other three structurally characterized dialkali metal tetraphenylethylene salts. The asymmetric unit contains one [Na(diglyme2]+ cation and one half of the [Ph2CCPh2]2− dianion. The latter lies on a twofold rotation axis. C—C bond-length redistribution displays that excessive electron density of the dianion is predominantly located at the C atoms of a former double bond and at all eight ortho positions. The studied crystal was a twin, with the ratio of two major components being 0.2143 (9:0.7857 (9. The twin operation is a twofold rotation around the a axis.

Reactive phase inversion for manufacture of asymmetric poly (ether imide sulfone) membranes

KAUST Repository

Jalal, Taghreed

2014-12-01

Poly (ether imide sulfone) membranes were manufactured by combining phase inversion and functionalization reaction between epoxy groups and amine modified polyether oligomers (Jeffamine) or TiO2 nanoparticles. Polysilsesquioxanes containing epoxy functionalities were in-situ grown in the casting solution and made available for further reaction with amines in the coagulation/annealing baths. The membranes were characterized by field emission scanning electron microscopy, porosimetry and water flux measurements. Water permeances up to 1500 l m-2 h-1 bar-1 were obtained with sharp pore size distribution and a pore diameter peak at 66 nm, confirmed by porosimetry, which allowed 99.2% rejection of γ-globulin. Water flux recovery of 77.5% was achieved after filtration with proteins. The membranes were stable in 50:50 dimethylformamide/water, 50:50 N-methyl pyrrolidone/water and 100% tetrahydrofuran. The possibility of using similar concept for homogeneous and stable attachment of nanoparticles on the membrane surface was demonstrated.

Manipulating the Morphology of P3HT–PCBM Bulk Heterojunction Blends with Solvent Vapor Annealing

KAUST Repository

Verploegen, Eric

2012-10-23

Using grazing incidence X-ray scattering, we observe the effects of solvent vapors upon the morphology of poly(3-hexylthiophene)-phenyl-C 61-butyric acid methyl ester (P3HT-PCBM) bulk heterojunction thin film blends in real time; allowing us to observe morphological rearrangements that occur during this process as a function of solvent. We detail the swelling of the P3HT crystallites upon the introduction of solvent and the resulting changes in the P3HT crystallite morphology. We also demonstrate the ability for tetrahydrofuran vapor to induce crystallinity in PCBM domains. Additionally, we measure the nanoscale phase segregated domain size as a function of solvent vapor annealing and correlate this to the changes observed in the crystallite morphology of each component. Finally, we discuss the implications of the morphological changes induced by solvent vapor annealing on the device properties of BHJ solar cells. © 2012 American Chemical Society.

[Studies on origin of illicit methamphetamine. I. The relationship of enantiomeric compositions between methamphetamine and its raw material (ephedrine)].

Science.gov (United States)

Kikura, R; Shimamine, M; Nakahara, Y; Terao, T

1992-01-01

In order to elucidate the relationship of enantiomeric compositions between methamphetamine (MA) and its raw materials, ephedrine (EP) enantiomers, commercial EP samples and MA samples prepared from them were analyzed by HPLC using GITC-prelabeling. The GITC derivatives were separated on ODS column using methanol-water-acetic acid (45:54:1) at a flow rate of 1.2 ml/min for EP and tetrahydrofuran-water-acetic acid (29:70:1) at a flow rate of 1 ml/min for MA. The chromatographic conditions resulted in such a good separation of four EP and two MA enantiomers that 1/1000 enantiomeric impurities could be detected and discriminated from the major enantiomer with good reproducibility. Moreover, it was demonstrated that the asymmetric center at alpha-position of amino group was entirely retained throughout the reductive reaction of the EP samples, and that the MA samples inherited the enantiomeric character from the EP samples used. This method was applied to discriminative analysis of MA samples seized in Japan.

Gas hydrate formation process for pre-combustion capture of carbon dioxide

International Nuclear Information System (INIS)

Lee, Hyun Ju; Lee, Ju Dong; Linga, Praveen; Englezos, Peter; Kim, Young Seok; Lee, Man Sig; Kim, Yang Do

2010-01-01

In this study, gas hydrate from CO 2 /H 2 gas mixtures with the addition of tetrahydrofuran (THF) was formed in a semi-batch stirred vessel at various pressures and temperatures to investigate the CO 2 separation/recovery properties. This mixture is of interest to CO 2 separation and recovery from Integrated Gasification Combine Cycle (IGCC) power plants. During hydrate formation the gas uptake was determined and composition changes in the gas phase were obtained by gas chromatography. The impact of THF on hydrate formation from the CO 2 /H 2 was observed. The addition of THF significantly reduced the equilibrium formation conditions. 1.0 mol% THF was found to be the optimum concentration for CO 2 capture based on kinetic experiments. The present study illustrates the concept and provides thermodynamic and kinetic data for the separation/recovery of CO 2 (pre-combustion capture) from a fuel gas (CO 2 /H 2 ) mixture.

Standard partial molar volumes of some electrolytes in ethylene carbonate based mixtures

International Nuclear Information System (INIS)

Zhao, Yang; Wang, Jianji.; Lu, Hui; Lin, Ruisen

2004-01-01

Apparent molar volumes V 2,phi and standard partial molar volumes V 2,phi 0 of LiClO 4 , LiBr and three symmetrical tetraalkylammonium bromides R 4 NBr (R=ethyl, propyl, butyl) have been determined at 298.15 K from precise density measurements in solvent mixtures of ethylene carbonate with tetrahydrofuran (THF), acetonitrile (AN), ethyl acetate (EA) and dimethoxyethane (DME). It is shown that the V 2,phi 0 values of LiClO 4 and LiBr are dependent strongly on the nature of the solvents, whereas the contribution of CH 2 group to the partial molar volume of the tetraalkylammonium salts has nothing to do with the nature of the solvents and the composition of the solvent mixtures. This provided a helpful evidence for the unsolvation of large tetraalkylammonium cations in organic solvents. The results have been discussed from ion-solvent interactions and the dielectric effect of the solvents

Bioactive Constituents of Zanthoxylum rhetsa Bark and Its Cytotoxic Potential against B16-F10 Melanoma Cancer and Normal Human Dermal Fibroblast (HDF Cell Lines

Directory of Open Access Journals (Sweden)

Ramesh Kumar Santhanam

2016-05-01

Full Text Available Zanthoxylum rhetsa is an aromatic tree, known vernacularly as “Indian Prickly Ash”. It has been predominantly used by Indian tribes for the treatment of many infirmities like diabetes, inflammation, rheumatism, toothache and diarrhea. In this study, we identified major volatile constituents present in different solvent fractions of Z. rhetsa bark using GC-MS analysis and isolated two tetrahydrofuran lignans (yangambin and kobusin, a berberine alkaloid (columbamine and a triterpenoid (lupeol from the bioactive chloroform fraction. The solvent fractions and purified compounds were tested for their cytotoxic potential against human dermal fibroblasts (HDF and mouse melanoma (B16-F10 cells, using the MTT assay. All the solvent fractions and purified compounds were found to be non-cytotoxic to HDF cells. However, the chloroform fraction and kobusin exhibited cytotoxic effect against B16-F10 melanoma cells. The presence of bioactive lignans and alkaloids were suggested to be responsible for the cytotoxic property of Z. rhetsa bark against B16-F10 cells.

Cambios histomorfológicos en el ovario del pez capitán, Eremophilus mutisii Humboldt 1805 (Pisces: Trichomyteridae, durante el ciclo reproductivo anual,en la laguna del Muña, sistema río Bogotá, Colombia

Directory of Open Access Journals (Sweden)

Plutarco Cala Cala

1982-01-01

Full Text Available The principal aim of this investigation was to study the anual morpho-histological changes in the ovary of the fish capitan, Eremophilus mutisii, in the Rio Bogota basin in Colombia, with regard to the reproductive cycle, size of the mature fishes and seasonal changes in the environment. The fibs material was collected monthly. The gonads were fixed in Bouin's fixative. Subsequently they were washed several times in 70% ethanol. Transversal sections of about 5 cm in length, each of which produced 10 slides with 10 or so sections per slide, were taken from the center to the anterior portion of the right ovary of each fish, since no macroscopic significant differencie was observed in the oogenic process in the anterior, central and posterior portion of the ovary. The sections were dehydrated in tetrahydrofuran and embedded in paraffin. Sections were cut at 6 microns and stained with haematoxylin and eosin (H & E. The gonosomatic index (GSI or maturity index (MIl was calculated.

Group type analysis of asphalt by column liquid chromatography

Energy Technology Data Exchange (ETDEWEB)

Zhang, C.; Yang, J.; Xue, Y.; Li, Y. [Chinese Academy of Science, Taiyuan (China)

2008-07-01

An improved analysis method for characterization of asphalt was established. The method is based on column chromatography technique. The asphalts were separated into four groups: saturates, aromatics, resins, and asphaltenes, quantitatively. About 0.1 g of sample was required in each analysis. About 20 mL of n-heptanes was used to separate out saturates first. Then about 35 mL of n-heptanes/dichloromethane (.5, v/v) mixture was used to separate out aromatics. About 30 mL of dichloromethane/tetrahydrofuran (1/3, v/v) mixture was used to separate out resin. The quality of the separation was confirmed by infrared spectra (IR) and {sup 1}H NMR analysis. The model compounds, tetracosan for saturates, dibenz(o)anthracen for aromatics, and acetanilide for resins were used for verification. The IR and {sup 1}H NMR analysis of the prepared fractions from the column liquid chromatography were in good agreement that of pure reagents.

Fiber reinforced silicon-containing arylacetylene resin composites

Directory of Open Access Journals (Sweden)

2007-12-01

Full Text Available A silicon-containing arylacetylene resin (SAR, a poly(dimethylsilyleneethynylene phenyleneethynylene (PMSEPE, was synthesized. The PMSEPE is a solid resin at ambient temperature with a softening temperature about 60°C and soluble in some solvents like tetrahydrofuran. The melt viscosity of the PMSEPE resin is less than 1 Pa•s. The resin could cure at the temperature of lower than 200°C. Fiber reinforced PMSEPE composites were prepared from prepregs which were made by the impregnation of fibers in PMSEPE resin solution. The composites exhibit good mechanical properties at room temperature and 250°C. The observation on fracture surfaces of the composites reinforced by glass fibers and carbon fibers demonstrates that the adhesion between the fibers and resin is good. The results from an oxyacetylene flame test show that the composites have good ablation performance and XRD analyses indicate that SiC forms in the residues during the ablation of the composites.

Ultrafast charge transfer and radiationless relaxations from higher excited state (S2) of directly linked Zn-porphyrin (ZP)-acceptor dyads: investigations into fundamental problems of exciplex chemistry

International Nuclear Information System (INIS)

Mataga, Noboru; Taniguchi, Seiji; Chosrowjan, Haik; Osuka, Atsuhiro; Yoshida, Naoya

2003-01-01

We have investigated photoinduced electron transfer and related processes from the higher excited electronic state (S 2 ) of Zn-porphyrin-imide acceptor directly linked supramolecular systems (ZP-I) designed especially for the critical studies of the energy gap law (EGL) of the charge separation (CS) from the S 2 state and solvent effects upon EGL. We have confirmed the modification of the EGL by change of solvent polarity from acetonitrile (ACN), tetrahydrofuran (THF) to toluene (Tol) and methyl-cyclohexane (MCH), from rather typical bell-shaped one in ACN to that with less prominent normal region and prominent inverted region with moderate slope extending over wider range of -ΔG CS values in nonpolar solvent MCH. We have demonstrated that these solvent effects upon EGL affect delicately various radiationless relaxation processes from S 2 state. We have examined also effects of the hydrogen bonding solvent ethanol (EtOH) on the EGL for CS and found very specific effect controlling the CS reaction and related processes

Pd/NbOPO₄ multifunctional catalyst for the direct production of liquid alkanes from aldol adducts of furans.

Science.gov (United States)

Xia, Qi-Neng; Cuan, Qian; Liu, Xiao-Hui; Gong, Xue-Qing; Lu, Guan-Zhong; Wang, Yan-Qin

2014-09-08

Great efforts have been made to convert renewable biomass into transportation fuels. Herein, we report the novel properties of NbO(x)-based catalysts in the hydrodeoxygenation of furan-derived adducts to liquid alkanes. Excellent activity and stability were observed with almost no decrease in octane yield (>90% throughout) in a 256 h time-on-stream test. Experimental and theoretical studies showed that NbO(x) species play the key role in C-O bond cleavage. As a multifunctional catalyst, Pd/NbOPO4 plays three roles in the conversion of aldol adducts into alkanes: 1) The noble metal (in this case Pd) is the active center for hydrogenation; 2) NbO(x) species help to cleave the C-O bond, especially of the tetrahydrofuran ring; and 3) a niobium-based solid acid catalyzes the dehydration, thus enabling the quantitative conversion of furan-derived adducts into alkanes under mild conditions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Differential cross sections for intermediate-energy electron scattering from α-tetrahydrofurfuryl alcohol: Excitation of electronic-states

Energy Technology Data Exchange (ETDEWEB)

Chiari, L.; Jones, D. B.; Thorn, P. A.; Pettifer, Z. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Duque, H. V. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG (Brazil); Silva, G. B. da [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Universidade Federal de Mato Grosso, Barra do Garças, Mato Grosso (Brazil); Limão-Vieira, P. [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Duflot, D. [Laboratoire de Physique des Lasers, Atomes et Molécules, UMR CNRS 8523, Université Lille, F-59655 Villeneuve d’Ascq Cedex (France); Hubin-Franskin, M.-J.; Delwiche, J. [Départment de Chimie, Université de Liège, Institut de Chimie-Bât. B6C, B-4000 Liège 1 (Belgium); Blanco, F. [Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, Madrid E-28040 (Spain); García, G. [Instituto de Física Fundamental, CSIC, Madrid E-28006 (Spain); and others

2014-07-14

We report on measurements of differential cross sections (DCSs) for electron impact excitation of a series of Rydberg electronic-states in α-tetrahydrofurfuryl alcohol (THFA). The energy range of these experiments was 20–50 eV, while the scattered electron was detected in the 10°–90° angular range. There are currently no other experimental data or theoretical computations against which we can directly compare the present measured results. Nonetheless, we are able to compare our THFA DCSs with earlier cross section measurements for Rydberg-state electronic excitation for tetrahydrofuran, a similar cyclic ether, from Do et al. [J. Chem. Phys. 134, 144302 (2011)]. In addition, “rotationally averaged” elastic DCSs, calculated using our independent atom model with screened additivity rule correction approach are also reported. Those latter results give integral cross sections consistent with the optical theorem, and supercede those from the only previous study of Milosavljević et al. [Eur. Phys. J. D 40, 107 (2006)].

Molecular Design of Soluble Biopolyimide with High Rigidity

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Sumant Dwivedi

2018-03-01

Full Text Available New soluble biopolyimides were prepared from a diamine derived from an exotic amino acid (4-aminocinnamic acid with several kinds of tetracarboxylic dianhydride. The biopolyimide molecular structural flexibility was tailored by modifying the tetracarboxylic dianhydride moiety. The obtained polyimides were soluble in various solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, and even tetrahydrofuran. It was observed that the biopolyimide solubility was greatly dependent upon the structural flexibility (torsion energy. Flexible structure facilitated greater solubility. The synthesized biopolyimides were largely amorphous and had number-average molecular weight (Mn in the range (5–8 × 105. The glass transition temperatures (Tg of the polymers ranged from 259–294 °C. These polymers exhibited good thermal stability without significant weight loss up to 410 °C. The temperatures at 10% weight loss (Td10 for synthesized biopolyimide ranged from 375–397 °C.

Radiation synthesis of the water-soluble, temperature sensitive polymer, copolymer and study on their properties

International Nuclear Information System (INIS)

Zhai Maolin; Yin Min; Ha Hongfei

1994-01-01

In order to obtain the water-soluble, temperature sensitive polymer and activated copolymer, the radiation polymerization of N-isopropylacrylamide (NIPAAm), radiation copolymerization of NIPAAm and N-acryloxysuccide (NASI) in aqueous solution or in buffer solution (PBS pH = 7.4) have been carried out by γ-rays from 60 Co source at room temperature. The optimum dose range (1-7 kGy), dose rate (>40 Gy/min) and monomer concentration (1%) were chosen through determining the monomer conversion yield and molecular weight (M w = 6.8 x 10 5 ) of product. Synthesis of the reversible linear polymer was performed in tetrahydrofuran (THF) as well. In this way a white powder product could be obtained which possesses of thermally reversible property too, when it was dissolved in water or PBS. The only disadvantages of this method is that the molecular weight of the polymer produced in THF was much lower than that in aqueous solution

Liquid chromatographic determination of aniline and derivatives in environmental waters at nanogram per litre levels using fluorescamine pre-column derivatization

Energy Technology Data Exchange (ETDEWEB)

Djozan, D. [Univ. of Tabriz (Iran, Islamic Republic of). Dept. of Analytical Chemistry; Faraj-Zadeh, M.A. [Univ. of Tabriz (Iran, Islamic Republic of). Dept. of Analytical Chemistry

1995-11-01

Fluorescamine (fluram) has been used as a fluorogenic compound for pre-column derivatization of aniline and some derivatives. Anilines were derivatized with fluram in citrate buffer media (pH 5.5) to form pyrrolinones. The highly fluorescence pyrrolinones were isolated and pre-concentrated by solid phase extraction. A reversed phase, Spherisorb RP-8 column and tetrahydrofuran: Water:formic acid (42:56:2) mobile phase was used for separation. Detection method was by a sensitive fluorimetric method and quantitation was at 395 and 495 nm. The various parameters such as reaction conditions between anilines and fluram, solid phase extraction and chromatographic separation were optimized. Calibrations were linear over the range considered with excellent correlation coefficients (r>0.999). Relative standard deviations are less than 2.5% and detection limits for aniline, p-toluidine, 4-chloroaniline and 4-bromoaniline were 6, 30, 6 and 8 ng L{sup -1}, respectively. This method has been used successfully for the determination of anilines in environmental waters. (orig.)

Electrochemical Properties and Speciation in Mg(HMDS)2-Based Electrolytes for Magnesium Batteries as a Function of Ethereal Solvent Type and Temperature.

Science.gov (United States)

Merrill, Laura C; Schaefer, Jennifer L

2017-09-19

Magnesium batteries are a promising alternative to lithium-ion batteries due to the widespread abundance of magnesium and its high specific volumetric energy capacity. Ethereal solvents such as tetrahydrofuran (THF) are commonly used for magnesium-ion electrolytes due to their chemical compatibility with magnesium metal, but the volatile nature of THF is a concern for practical application. Herein, we investigate magnesium bis(hexamethyldisilazide) plus aluminum chloride (Mg(HMDS) 2 -AlCl 3 ) electrolytes in THF, diglyme, and tetraglyme at varying temperature. We find that, despite the higher thermal stability of the glyme-based electrolytes, THF-based electrolytes have better reversibility at room temperature. Deposition/stripping efficiency is found to be a strong function of temperature. Diglyme-based Mg(HMDS) 2 -AlCl 3 electrolytes are found to not exchange as quickly as THF and tetraglyme, stabilizing AlCl 2 + and facilitating undesired aluminum deposition. Raman spectroscopy, 27 Al NMR, and mass spectrometry are used to identify solution speciation.

Turn-on fluorescence chemosensor for fluoride ions and its applicability in imaging of living cells

Energy Technology Data Exchange (ETDEWEB)

Ponnuvel, Kandasamy; Padmini, Vediappen, E-mail: padimini_tamilenthi@yahoo.co.in

2016-01-15

The study was easy to prepare fluorescent chemosensor, the urea based triphenylamine conjugated ligand and structurally simple anion probes displayed great selectivity for the fluoride anion over other anions in an aqueous tetrahydrofuran solution. The probe was characterized using NMR spectroscopy, UV–visible, emission spectroscopy and mass spectrometry. The sensor showed spectral shifts and intensity changes in the presence of fluoride anions. The Job’s plot analysis indicates that the binding stoichiometry to be 1:1. Furthermore, by means of confocal fluorescent microscopy experiments, it has been demonstrated that it can be used as a fluorescent probe for monitoring fluoride ions in the living cells. - Highlights: • A novel fluorescent chemosensor for the detection of F{sup −} anions. • Detection of F{sup −} anions can be performed in water at pH=7.4. • The chemosensor could be efficiently delivered to live cells for bioimaging of F{sup −}.

Groundwater Monitoring and Tritium-Tracking Plan for the 200 Area State-Approved Land Disposal Site

Energy Technology Data Exchange (ETDEWEB)

Barnett, D. Brent

2000-08-31

The 200 Area State-Approved Land Disposal Site (SALDS) is a drainfield which receives treated wastewater, occasionally containing high levels of tritium from treatment of Hanford Site liquid wastes. Only the SALDS proximal wells (699-48-77A, 699-48-77C, and 699-48-77D) have been affected by tritium from the facility thus far; the highest activity observed (2.1E+6 pCi/L) occurred in well 699-48-77D in February 1998. Analytical results of groundwater geochemistry since groundwater monitoring began at the SALDS indicate that all constituents with permit enforcement limits have been below those limits with the exception of one measurement of total dissolved solids (TDS) in 1996. The revised groundwater monitoring sampling and analysis plan eliminates chloroform, acetone, tetrahydrofuran, benzene, and ammonia as constituents. Replicate field measurements will replace laboratory measurements of pH for compliance purposes. A deep companion well to well 699-51-75 will be monitored for tritium deeper in the uppermost aquifer.

Bioinspired total synthesis of tetrahydrofuran lignans by tandem nucleophilic addition/redox isomerization/oxidative coupling and cycloetherification reactions as key steps

Czech Academy of Sciences Publication Activity Database

Jagtap, Pratap; Císařová, I.; Jahn, Ullrich

2018-01-01

Roč. 16, č. 5 (2018), s. 750-755 ISSN 1477-0520 R&D Projects: GA ČR GA203/09/1936 Institutional support: RVO:61388963 Keywords : oxygenated benzylic alcohols * transition metal complexes * allylic alcohols Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 3.564, year: 2016 http://pubs.rsc.org/en/content/articlehtml/2018/ob/c7ob02848b

Synthesis, characterization and biological activity of ring-substituted 6-benzylamino-9-tetrahydropyran-2-yl and 9-tetrahydrofuran-2-ylpurine derivatives

Czech Academy of Sciences Publication Activity Database

Szüčová, Lucie; Spíchal, Lukáš; Doležal, Karel; Zatloukal, Marek; Greplová, Jarmila; Galuszka, P.; Kryštof, Vladimír; Voller, Jiří; Popa, Igor; Massino, F.J.; Jorgensen, J.E.; Strnad, Miroslav

2009-01-01

Roč. 17, č. 5 (2009), s. 1938-1947 ISSN 0968-0896 R&D Projects: GA MŠk 1M06030; GA ČR GA522/09/1576; GA ČR(CZ) GA522/08/0920 Institutional research plan: CEZ:AV0Z50380511 Keywords : Cytokinins * Antisenescence * Receptor Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.822, year: 2009

Uranium(iii) complexes supported by hydrobis(mercaptoimidazolyl)borates: synthesis and oxidation chemistry.

Science.gov (United States)

Maria, Leonor; Santos, Isabel C; Santos, Isabel

2018-05-23

The reaction of [UI3(thf)4] with the sodium or lithium salts of hydrobis(2-mercapto-1-methylimidazolyl)borate ligands ([H(R)B(timMe)2]-) in a 1 : 2 ratio, in tetrahydrofuran, gave the U(iii) complexes [UI{κ3-H,S,S'-H(R)B(timMe)2}2(thf)2] (R = H (1), Ph (2)) in good yields. Crystals of [UI{κ3-H,S,S'-H(Ph)B(timMe)2}2(thf)2] (2) were obtained by recrystallization from a tetrahydrofuran/acetonitrile solution, and the ion-separated uranium complex [U{κ3-H,S,S'-H(Ph)B(timMe)2}2(CH3CN)3][I] (3-I) was obtained by dissolution of 2 in acetonitrile followed by recrystallization. One-electron oxidation of 2 with AgBPh4 or I2 resulted in the formation of the cationic U(iv) complexes [U{κ3-H,S,S'-H(Ph)B(timMe)2}3][X] (X = BPh4 (6-BPh4), I (6-I)), due to a ligand redistribution process. These complexes are the first examples of homoleptic poly(azolyl)borate U(iv) complexes. Treatment of complex 2 with azobenzene led to the isolation of crystals of the U(iv) compound [UI{κ3-H(Ph)B(timMe)2}2(κ2-timMe)] (7). Treatment of 2 with pyridine-N oxide (pyNO) led to the formation of the uranyl complex [UO2{κ2-S,S'-H(Ph)B(timMe)2}2] (8) and of complex 6-I, while from the reaction of [U{κ3-H(Ph)B(timMe)2}2(thf)3][BPh4] (5) with pyNO, the oxo-bridged U(iv) complex [{U{κ3-H(Ph)B(timMe)2}2(pyNO)}2(μ-O)][BPh4]2 (9) was also obtained. In the U(iii) and U(iv) complexes, the bis(azolyl)borate ligands bind to the uranium center in a κ3-H,S,S' coordination mode, while in the U(vi) complex the ligands bind to the metal in a κ2-S,S' mode. The presence of UH-B interactions in the solid-state, for the nine-coordinate complexes 1, 2, 3, 6 and 7 and for the eight-coordinate complex 9, was supported by IR spectroscopy and/or X-ray diffraction analysis.

3,5-Bis[1-acetyl-5-(4-chlorophenyl-4,5-dihydro-1H-pyrazol-3-yl]-2,6-dimethylpyridine tetrahydrofuran solvate

Directory of Open Access Journals (Sweden)

Qun Qian

2008-07-01

Full Text Available In the title compound, C29H27Cl2N5O2·C4H8O, the polycyclic system is composed of three parts: one central pyridine ring substituted by two functionalized pyrazoline rings. The dihedral angles between the central pyridine plane and pyrazoline planes are 5.11 (1 and 13.99 (1°, whereas the dihedral angles between each chlorophenyl plane and the attached pyrazoline planes are 88.65 (1 and 83.87 (1°. Molecules are linked by intermolecular C—H...O hydrogen bonds, forming a three-dimensional network.

Non-aqueous capillary electrophoresis with red light emitting diode absorbance detection for the analysis of basic dyes.

Science.gov (United States)

Fakhari, Ali Reza; Breadmore, Michael C; Macka, Miroslav; Haddad, Paul R

2006-11-24

Non-aqueous capillary electrophoresis was evaluated for the separation of five hydrophobic basic blue dyes for application in forensic dye analysis. The use of a red light emitting diode as a high intensity, low-noise light source provided sensitive detection of the blue dyes while also allowing the evaluation of solvents that absorb strongly in the UV region. Excellent peak shapes and separation selectivity were obtained in methanol, ethanol, acetonitrile and dimethylsulfoxide, however water, tetrahydrofuran, dimethylformamide and acetone were unsuitable as solvents due to poor peak shapes and a lack of sensitivity, most likely due to adsorption onto the capillary wall. Due to the known compatibility of methanol with capillary electrophoresis-mass spectrometry, this solvent was examined further with the relative acidity/basicity of the electrolyte being optimised with an artificial neural network. The optimised method was examined for the separation of ink samples from 6 fibre tip and 2 ball point blue or black pens and showed that a unique migration time for the main dye component in seven of the eight pens could be obtained.

Reduction of Furfural to Furfuryl Alcohol in Liquid Phase over a Biochar-Supported Platinum Catalyst

Directory of Open Access Journals (Sweden)

Ariadna Fuente-Hernández

2017-02-01

Full Text Available In this work, the liquid phase hydrogenation of furfural has been studied using a biochar-supported platinum catalyst in a batch reactor. Reactions were performed between 170 °C and 320 °C, using 3 wt % and 5 wt % of Pt supported on a maple-based biochar under hydrogen pressure varying from 500 psi to 1500 psi for reaction times between 1 h and 6 h in various solvents. Under all reactive conditions, furfural conversion was significant, whilst under specific conditions furfuryl alcohol (FA was obtained in most cases as the main product showing a selectivity around 80%. Other products as methylfuran (MF, furan, and trace of tetrahydrofuran (THF were detected. Results showed that the most efficient reaction conditions involved a 3% Pt load on biochar and operations for 2 h at 210 °C and 1500 psi using toluene as solvent. When used repetitively, the catalyst showed deactivation although only a slight variation in selectivity toward FA at the optimal experimental conditions was observed.

Tris(2,2'-bipyridyl) ruthenium(II)-bisoprolol-based electrochemiluminescence coupled with capillary zone electrophoresis

Energy Technology Data Exchange (ETDEWEB)

Wang Jingwu [Department of Chemistry, Nanchang University, Nanchang 330031 (China)], E-mail: wangjingwu@ncu.edu.cn; Zhang Xiaojun; Pi Fangfang [Department of Chemistry, Nanchang University, Nanchang 330031 (China); Wang Xiaoxia [Graduate School of Engineering, University of Fukui, Fukui 910-8507 (Japan); Yang Nianjun [Diamond Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Central 2-13, 1-1-1 Umezono, Tsukuba 305-8568 (Japan)], E-mail: nianjun.yang@iaf.fraunhofer.de

2009-03-01

Capillary zone electrophoresis (CZE) coupled with tris(2,2'-bipyridyl) ruthenium(II)-based end-column electrogenerated chemiluminescence (ECL) has been utilized to detect bisoprolol in drugs and tablets after its separation from metoprolol. Tetrahydrofuran was used as an additive in the running buffer to obtain the absolute ECL peak of bisoprolol. Bisoprolol reacts as a co-reactant in tris(2,2'-bipyridyl) ruthenium(II) ECL system. Under the optimized experimental conditions, bisoprolol was separated successfully and efficiently from metoprolol and other co-existed materials in tablets and urine samples. The ECL intensity of tris(2,2'-bipyridyl) ruthenium(II)-bisoprolol-based system is linear with the concentration of bisoprolol from 1.5 {mu}M to 0.3 mM with a detection limit of 0.3 {mu}M. Relative standard derivations of the ECL intensity are 2.58% for the detection of 15 {mu}M bisoprolol. This method is a simple, rapid, selective, and sensitive. It was applied successfully for the monitoring of bisoprolol in market available tablets and human urine samples.

SYNTHESIS OF TETRA-p-PROPENYLTETRAESTERCALIX[4]ARENE AND TETRA-p-PROPENYLTETRACARBOXYLICACIDCALIX[4]ARENE FROM p-t-BUTYLPHENOL

Directory of Open Access Journals (Sweden)

Triana Kusumaningsih

2010-06-01

Full Text Available A research has been conducted to synthesize tetra-p-propenyltetraestercalix[4]arene and tetra-p-propenyltetracarboxylicacidcalix[4] arene using p-t-butylphenol as a starting material. The synthesis was carried out in following stages, i.e (1 synthesis of p-t-butylcalix[4]arene from p-t-butylphenol, (2 debutylation of p-t-butylcalix[4]arene, (3 tetraallilation of 25,26,27,28-tetrahydroxycalix[4]arene with NaH and allilbromida in dry tetrahydrofuran, (4 Claissen rearrangement of 25,26,27,28-tetrapropenyloxycalix[4]arene, (5 esterification of tetra-p-propenyltetrahydroxycalix[4]arene, (6 hydrolisis of tetra-p-propenyltetraestercalix[4]arene. The all structures of products were observed by means of melting point, FTIR, and 1H-NMR spectrometers. Tetra-p-propenyltetraestercalix[4]arene compound was obtained as yellow liquid product in 55.08% yield. Tetra-p-propenyltetracarboxylicacidcalix[4]arene compound was obtained as white solid product with the melting point 135-137 °C at decomposed and in 70.05% yield.   Keywords: calix[4]arene, Claissen rearrangement, esterification, hydrolisis

Density functional theory study of chemical sensing on surfaces of single-layer MoS2 and graphene

International Nuclear Information System (INIS)

Mehmood, F.; Pachter, R.

2014-01-01

In this work, density functional theory (DFT) calculations have been used to investigate chemical sensing on surfaces of single-layer MoS 2 and graphene, considering the adsorption of the chemical compounds triethylamine, acetone, tetrahydrofuran, methanol, 2,4,6-trinitrotoluene, o-nitrotoluene, o-dichlorobenzene, and 1,5-dicholoropentane. Physisorption of the adsorbates on free-standing surfaces was analyzed in detail for optimized material structures, considering various possible adsorption sites. Similar adsorption characteristics for the two surface types were demonstrated, where inclusion of a correction to the DFT functional for London dispersion was shown to be important to capture interactions at the interface of molecular adsorbate and surface. Charge transfer analyses for adsorbed free-standing surfaces generally demonstrated very small effects. However, charge transfer upon inclusion of the underlying SiO 2 substrate rationalized experimental observations for some of the adsorbates considered. A larger intrinsic response for the electron-donor triethylamine adsorbed on MoS 2 as compared to graphene was demonstrated, which may assist in devising chemical sensors for improved sensitivity

Supercritical gas extracts from low-quality coals. On the search of new precursors for carbon materials

Energy Technology Data Exchange (ETDEWEB)

Garcia, Roberto; Arenillas, Ana; Rubiera, Fernando; Moinelo, Sabino R. [Instituto Nacional del Carbon INCAR, CSIC, Apartado 73, 33080, Oviedo (Spain)

2004-11-25

This paper studies the chemical composition of several supercritical gas (SCG) extracts and its influence on the thermal behaviour under carbonisation conditions. The extracts were obtained from a Spanish lignite (Mequinenza), a low-quality coal from the point of view of energy applications. The lignite was treated with toluene, ethanol (EtOH) and tetrahydrofuran (THF) as solvents under different supercritical temperature and pressure conditions. The extracts display high aliphatic nature and enhanced concentrations of oxygen functional groups, aided by the contribution of hydrogenation and oxygen incorporation reactions occurring in the SCG extraction with EtOH and THF. Thiophenic compounds are also present in great concentrations derived from the exceptionally high organic sulphur content of the parent coal. The carbonisation of the extracts renders anisotropic material with fine mosaic texture, as a consequence of the significant thermal reactivity inferred by the aliphatic and oxygenated groups. The size of the mosaic increases with the temperature of the SCG extraction and varies with the supercritical solvent in the order: toluene

Organic molecules based on dithienyl-2,1,3-benzothiadiazole as new donor materials for solution-processed organic photovoltaic cells

Energy Technology Data Exchange (ETDEWEB)

Wu, Zhonglian; Fan, Benhu; Ouyang, Jianyong [Department of Materials Science and Engineering, National University of Singapore, Singapore 117574 (Singapore); Xue, Feng [Department of Chemistry, National University of Singapore, Singapore 117573 (Singapore); Adachi, Chihaya [Center for Future Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan)

2010-12-15

Polymers based on dithienyl-2,1,3-benzothiadiazole (TBT) have received strong attention as the donor materials of polymer photovoltaic cells (PVs), since they can have a low band gap. But soluble small organic molecules based on TBT have been rarely studied. This paper reports the synthesis of two small organic molecules based on TBT and their application as the donor materials of solution-processed bulk heterojunction organic photovoltaic cells (OPVs). These compounds were soluble in common organic solvents, such as chloroform, chlorobenzene and tetrahydrofuran. They have band gaps comparable to poly(3-hexylthiophene) (P3HT) and lower HOMO and LUMO (HOMO: highest occupied molecular orbital, LUMO: lowest unoccupied molecular orbital) levels than P3HT. These molecules and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) were used as the donors and acceptor to fabricate bulk heterojunction OPVs through solution processing. After optimization of the experimental conditions, power conversion efficiency (PCE) of 0.66% was achieved on the solution-processed OPVs under AM 1.5G, 100 mW cm{sup -2} illumination. (author)

Evolution of the Copper Surface in the Course of Oxidation by CCl4-L (L=THF, Dmf, Dmso): Scanning Probe Microscope Study

Science.gov (United States)

Panteleev, S. V.; Maslennikov, S. V.; Ignatov, S. K.; Spirina, I. V.; Kruglova, M. V.; Gribkov, B. A.; Vdovichev, S. N.

2013-04-01

The evolution of compact surface of the 100 nm copper film deposited on the glass-ceramics doped with vanadium coating in the course of the oxidation by the CCl4-L (L = dimethylformamide (DMF), tetrahydrofuran (THF), dimethylsulfoxide (DMSO), CCl4 concentration ≈ 1 mol/L) was studied by atomic force microscopy (AFM) in contact mode. The dynamics of active centers formation and destruction was investigated in the course of the oxidation process. The metallic sample dissolution rate was estimated as a function of the coordinating solvent nature. The development of the metal surface oxidation was established to lead to a significant increase of surface roughness. This phenomenon can be explained by the fact that different parts of the surface react at different rates. Further course of the reaction leads to a significant decrease of the surface roughness of copper films. The amount of the metal reacted has an almost linear dependence on the reaction time. AFM scans indicate that there is the same mechanism of the reaction between copper and carbon tetrachloride for all solvents.

Crosslinked copolyazoles with a zwitterionic structure for organic solvent resistant membranes

KAUST Repository

Chisca, Stefan

2015-01-01

The preparation of crosslinked membranes with a zwitterionic structure based on a facile reaction between a newly synthesized copolyazole with free OH groups and (3-glycidyloxypropyl)trimethoxysilane (GPTMS) is reported. The new OH-functionalized copolyazole is soluble in common organic solvents, such as tetrahydrofuran (THF), dimethylsulfoxide (DMSO), N,N′-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP) and can be easily processed by phase inversion. After crosslinking with GPTMS, the membranes acquire high solvent resistance. We show the membrane performance and the influence of the crosslinking reaction conditions on the thermal stability, surface polarity, pore morphology, and solvent resistance. By using UV-spectroscopy we monitored the solvent resistance of the membranes in four aggressive solvents (THF, DMSO, DMF and NMP) for 30 days. After this time, only minor changes (less than 2%) were detected for membranes subjected to a crosslinking reaction for 6 hours or longer. Our data suggest that the novel crosslinked membranes can be used for industrial applications in wide harsh environments in the presence of organic solvents.

A fast response hafnium selective polymeric membrane electrode based on N,N'-bis(α-methyl-salicylidene)-dipropylenetriamine as a neutral carrier

International Nuclear Information System (INIS)

Rezaei, B.; Meghdadi, S.; Zarandi, R. Fazel

2008-01-01

In this study a new hafnium selective sensor was fabricated from polyvinylchloride (PVC) matrix membrane containing neutral carrier N,N'-bis(α-methyl-salicylidene)-dipropylenetriamine (Mesaldpt) as a new ionophore, sodium tetraphenyl borate (NaTPB) as anionic discriminator and dioctyl phthalate (DOP) as plasticizing solvent mediator in tetrahydrofuran solvent. The electrode exhibits Nernstian response for Hf 4+ (Hafnium(IV)) over a wide concentration range (2.0 x 10 -7 to 1.0 x 10 -1 M) with the determination coefficient of 0.9966 and slope of 15.1 ± 0.1 mV decades -1 . The limit of detection is 1.9 x 10 -7 M. The electrode has a fast response time of 18 s and a working pH range of 4-8. The proposed membrane shows excellent discriminating ability towards Hf 4+ ion with regard to several alkali, alkaline earth transition and heavy metal ions. It can be used over a period of 1.5 months with good reproducibility. It is successfully applied for direct determination of Hf 4+ in solutions by standard addition method for real sample analysis

Mechanical polishing as an improved surface treatment for platinum screen-printed electrodes

Directory of Open Access Journals (Sweden)

Junqiao Lee

2016-07-01

Full Text Available The viability of mechanical polishing as a surface pre-treatment method for commercially available platinum screen-printed electrodes (SPEs was investigated and compared to a range of other pre-treatment methods (UV-Ozone treatment, soaking in N,N-dimethylformamide, soaking and anodizing in aqueous NaOH solution, and ultrasonication in tetrahydrofuran. Conventional electrochemical activation of platinum SPEs in 0.5 M H2SO4 solution was ineffective for the removal of contaminants found to be passivating the screen-printed surfaces. However, mechanical polishing showed a significant improvement in hydrogen adsorption and in electrochemically active surface areas (probed by two different redox couples due to the effective removal of surface contaminants. Results are also presented that suggest that SPEs are highly susceptible to degradation by strong acidic or caustic solutions, and could potentially lead to instability in long-term applications due to continual etching of the binding materials. The ability of SPEs to be polished effectively extends the reusability of these traditionally “single-use” devices. Keywords: Screen-printed electrodes, Polishing, Platinum, Activation, Pre-treatment, Cyclic voltammetry

Tin Oxide Nanoparticles: Synthesis, Characterization and Study their Particle Size at Different Current Density

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Karzan A. Omar

2013-11-01

Full Text Available Tin oxide nanoparticles are prepared by electrochemical reduction method using tetrapropylammonium bromide (TPAB and tetrabutylammonium bromide (TBAB as structure directing agent in an organic medium viz. tetrahydrofuran (THF and acetonitrile (ACN in 4:1 ratio by optimizing current density and molar concentration of the ligand. The reduction process takes place under an inert atmosphere of nitrogen over a period of 2 h. Such nanoparticles are prepared by using a simple electrolysis cell in which the sacrificial anode as a commercially available in tin metal sheet and platinum (inert sheet act as a cathode. The parameters such as current density, solvent polarity, distance between electrodes and concentration of stabilizers are used to control the size of nanoparticles. The synthesized tin oxide nanoparticles are characterized by using UV–Visible, FT-IR and SEM–EDS analysis techniques. UV-Visible spectroscopy has revealed the optical band gap to be 4.13, 4.16 and 4.24 ev for (8, 10 and 12 mA/cm2 and the effect of current density on theirs particle size, respectively.

Solvent Influences on the Molecular Aggregation of Magnesium Aryloxides

Energy Technology Data Exchange (ETDEWEB)

ZECHMANN,CECILIA A.; BOYLE,TIMOTHY J.; RODRIGUEZ,MARK A.; KEMP,RICHARD A.

2000-07-14

Magnesium aryloxides were prepared in a variety of solvents through the reaction of dibutyl magnesium with sterically varied aryl alcohols: 2,6-dimethylphenol (H-DMP), 2,6-diisopropylphenol (H-DIP), and 2,4,6-trichlorophenol (H-TCP). Upon using a sufficiently strong Lewis-basic solvent, the monomeric species Mg(DMP){sub 2}(py){sub 3} (1, py = pyridine), Mg(DIP){sub 2}(THF){sub 3}, (2a, THF = tetrahydrofuran) Mg(TCP){sub 2}(THF){sub 3} (3) were isolated. Each of these complexes possesses a five-coordinate magnesium that adopts a trigonal bipyramidal geometry. In the absence of a Lewis base, the reaction with H-DIP yields a soluble trinuclear complex, [Mg(DIP){sub 2}]{sub 3} (2b). The Mg metal centers in 2b adopt a linear arrangement with a four-coordinate central metal while the outer metal centers are reduced to just three-coordinate. Solution spectroscopic methods suggest that while 2b remains intact, the monomeric species (1, 2a, and 3) are involved in equilibria, which facilitate intermolecular ligand transfer.

Mesoporous activated carbons with metal-oxide particles prepared from Morwell coal; Morwell tan wo genryo to shita kinzoku sankabutsu tanji kasseitan no saiko kozo

Energy Technology Data Exchange (ETDEWEB)

Yoshizawa, N.; Yamada, Y.; Shiraishi, M. [National Institute for Resources and Environment, Tsukuba (Japan); Kojima, S.; Tamai, H.; Yasuda, H. [Hiroshima University, Hiroshima (Japan). Faculty of Engineering

1996-10-28

The metal dependence of mesoporous activated carbons with various metal acetylacetonate (acac) particles prepared from Morwell coal was studied. In experiment, the mixture of Morwell coal and acac metal complexes were dissipated into tetrahydrofuran, and after agitation in Ar atmosphere, the solvent was removed by vacuum distillation. Coal specimens with Fe(acac)3, Ni(acac)2 and Co(acac)2 as acac complexes were activated by exchanging flow gas with water vapor after heat treatment in N2 gas flow at 900{degree}C. The pore sizes of the specimens were obtained from N2 adsorption isotherms by BET method and BJH method. Conditions of pores and metals in the specimens were examined by XRD measurement and TEM observation. The relation between the above conditions and pore characteristics obtained from adsorption experiment was also examined. As a result, the difference in mesopore ratio between the specimens and blank specimens was larger in the order of Fe, Co and Ni, and the effect of added metal complexes was also larger in this order. 3 refs., 3 figs., 3 tabs.

Exploiting hidden symmetry in natural products: total syntheses of amphidinolides C and F.

Science.gov (United States)

Mahapatra, Subham; Carter, Rich G

2013-07-24

The total synthesis of amphidinolide C and a second-generation synthesis of amphidinolide F have been accomplished through the use of a common intermediate to access both the C1-C8 and the C18-C25 sections. The development of a Ag-catalyzed cyclization of a propargyl benzoate diol is described to access both trans-tetrahydrofuran rings. The evolution of a Felkin-controlled, 2-lithio-1,3-dienyl addition strategy to incorporate C9-C11 diene as well as C8 stereocenter is detailed. Key controlling aspects in the sulfone alkylation/oxidative desulfurization to join the major subunits, including the exploration of the optimum masking group for the C18 carbonyl motif, are discussed. A Trost asymmetric alkynylation and a stereoselective cuprate addition to an alkynoate have been developed for the rapid construction of the C26-C34 subunit. A Tamura/Vedejs olefination to introduce the C26 side arm of amphidnolides C and F is employed. The late-stage incorporation of the C15, C18 diketone motif proved critical to the successful competition of the total syntheses.

[6-chloro-3-pyridylmethyl-3H]neonicotinoids as high-affinity radioligands for the nicotinic acetylcholine receptor: preparation using NaB3H4 and LiB3H4

International Nuclear Information System (INIS)

Latli, Bachir; Casida, J.E.

1996-01-01

NaB 3 H 4 and LiB 3 H 4 at 78% and 97% isotopic enrichments, respectively, were used in the synthesis of 3 H-labeled 1-(6-chloro-3-pyridyl)-methyl-2-nitromethyleneimidazolidine (CH-IMI) and N'-[(6-chloro-3-pyridyl)methyl]-n''-cyano-n'-methylacetamidine (acetamiprid) (two very potent insecticides) and of 1-(6-chloro-3-pyridyl)methyl-2-iminoimidazolidine (desnitro-IMI) (a metabolite of the commercial insecticides imidacloprid). 6-Chloronicotinoyl chloride was treated with either NaB 3 H 4 in methanol or LiB 3 H 4 in tetrahydrofuran and the resulting alcohol transformed to 2-chloro-5-chloromethylpyridine, which was then coupled to N-cyano-N'-methylacetamidine to give [ 3 H] acetamiprid (45 Ci/mmol). 2-Chloro-5-chloro[ 3 H]methylpyridine was also reacted with ethylenediamine and the product was either refluxed in absolute ethanol with 1,1-bis(methylthio)-2-nitro-ethylene to provide [ 3 H]CH-IMI or reacted in toluene with a solution of cyanogen bromide to produce [ 3 H] desnitro-IMI (each 55 Ci/mmol. (author)

Direct functionalization of pristine single-walled carbon nanotubes by diazonium-based method with various five-membered S- or N- heteroaromatic amines

International Nuclear Information System (INIS)

Leinonen, Heli; Lajunen, Marja

2012-01-01

Reactivity of five-membered, variously substituted, heteroaromatic diazonium salts was studied toward pristine single-walled carbon nanotubes (SWCNTs), prepared by high-pressure CO conversion (HiPCO) method. Average size range of individual HiPCO SWCNTs was 0.8–1.2 nm (diameter) and 100–1,000 nm (length). Functionalizations were performed by a one-pot diazotization–dediazotization method with methyl-2-aminothiophene-3-carboxylate, 2-aminothiophene-3-carbonitrile, 2-aminoimidazole sulfate, or 3-aminopyrazole in acetic acid using sodium nitrite at room temperature or by heating. According to Raman and Fourier transform infrared spectroscopy, all used heterocyclic diazonium salts formed a covalent bond with SWCNTs and yielded new kinds of five-membered heterocycle-functionalized SWCNTs. Methyl-2-thiophenyl-3-carboxylate-functionalized SWCNTs formed a highly soluble, stable dispersion in tetrahydrofuran (THF), 3-pyrazoyl-functionalized SWCNTs in ethanol, and 2-imidazoyl- or 2-thiophenyl-3-carbonitrile-functionalized SWCNTs in ethanol and THF. The thermogravimetric analysis as well as energy-filtered transmission electron microscopy imaging of the products confirmed the successful functionalization of SWCNTs.

Direct functionalization of pristine single-walled carbon nanotubes by diazonium-based method with various five-membered S- or N- heteroaromatic amines

Energy Technology Data Exchange (ETDEWEB)

Leinonen, Heli; Lajunen, Marja, E-mail: marja.lajunen@oulu.fi [University of Oulu, Department of Chemistry (Finland)

2012-09-15

Reactivity of five-membered, variously substituted, heteroaromatic diazonium salts was studied toward pristine single-walled carbon nanotubes (SWCNTs), prepared by high-pressure CO conversion (HiPCO) method. Average size range of individual HiPCO SWCNTs was 0.8-1.2 nm (diameter) and 100-1,000 nm (length). Functionalizations were performed by a one-pot diazotization-dediazotization method with methyl-2-aminothiophene-3-carboxylate, 2-aminothiophene-3-carbonitrile, 2-aminoimidazole sulfate, or 3-aminopyrazole in acetic acid using sodium nitrite at room temperature or by heating. According to Raman and Fourier transform infrared spectroscopy, all used heterocyclic diazonium salts formed a covalent bond with SWCNTs and yielded new kinds of five-membered heterocycle-functionalized SWCNTs. Methyl-2-thiophenyl-3-carboxylate-functionalized SWCNTs formed a highly soluble, stable dispersion in tetrahydrofuran (THF), 3-pyrazoyl-functionalized SWCNTs in ethanol, and 2-imidazoyl- or 2-thiophenyl-3-carbonitrile-functionalized SWCNTs in ethanol and THF. The thermogravimetric analysis as well as energy-filtered transmission electron microscopy imaging of the products confirmed the successful functionalization of SWCNTs.

Direct functionalization of pristine single-walled carbon nanotubes by diazonium-based method with various five-membered S- or N- heteroaromatic amines

Science.gov (United States)

Leinonen, Heli; Lajunen, Marja

2012-09-01

Reactivity of five-membered, variously substituted, heteroaromatic diazonium salts was studied toward pristine single-walled carbon nanotubes (SWCNTs), prepared by high-pressure CO conversion (HiPCO) method. Average size range of individual HiPCO SWCNTs was 0.8-1.2 nm (diameter) and 100-1,000 nm (length). Functionalizations were performed by a one-pot diazotization-dediazotization method with methyl-2-aminothiophene-3-carboxylate, 2-aminothiophene-3-carbonitrile, 2-aminoimidazole sulfate, or 3-aminopyrazole in acetic acid using sodium nitrite at room temperature or by heating. According to Raman and Fourier transform infrared spectroscopy, all used heterocyclic diazonium salts formed a covalent bond with SWCNTs and yielded new kinds of five-membered heterocycle-functionalized SWCNTs. Methyl-2-thiophenyl-3-carboxylate-functionalized SWCNTs formed a highly soluble, stable dispersion in tetrahydrofuran (THF), 3-pyrazoyl-functionalized SWCNTs in ethanol, and 2-imidazoyl- or 2-thiophenyl-3-carbonitrile-functionalized SWCNTs in ethanol and THF. The thermogravimetric analysis as well as energy-filtered transmission electron microscopy imaging of the products confirmed the successful functionalization of SWCNTs.

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level

KAUST Repository

Habuchi, Satoshi

2016-09-26

We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single molecule level. An electrostatic self-assembly and covalent fixation (ESA-CF) process is used for the synthesis of the cyclic poly(tetrahydrofuran) (poly(THF)). The diffusive motion of individual cyclic polymer chains in a melt state is visualized using single molecule fluorescence imaging by incorporating a fluorophore unit in the cyclic chains. The diffusive motion of the chains is quantitatively characterized by means of a combination of mean-squared displacement (MSD) analysis and a cumulative distribution function (CDF) analysis. The cyclic polymer exhibits multiple-mode diffusion which is distinct from its linear counterpart. The results demonstrate that the diffusional heterogeneity of polymers that is often hidden behind ensemble averaging can be revealed by the efficient synthesis of the cyclic polymers using the ESA-CF process and the quantitative analysis of the diffusive motion at the single molecule level using the MSD and CDF analyses.

Fabrication of band gap engineered nanostructured tri-metallic (Mn-Co-Ti) oxide thin films

Science.gov (United States)

Mansoor, Muhammad Adil; Yusof, Farazila Binti; Nay-Ming, Huang

2018-04-01

In continuation of our previous studies on photoelectrochemical (PEC) properties of titanium based composite oxide thin films, an effort is made to develop thin films of 1:1:2 manganese-cobalt-titanium oxide composite, Mn2O3-Co2O3-4TiO2 (MCT), using Co(OAc)2 and a bimetallic manganese-titanium complex, [Mn2Ti4(TFA)8(THF)6(OH)4(O)2].0.4THF (1), where OAc = acetato, TFA = trifluoroacetato and THF = tetrahydrofuran, via aerosol-assisted chemical vapour deposition (AACVD) technique. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopic analyses confirmed formation of thin film of Mn2O3-Co2O3-4TiO2 composite material with uniformly distributed agglomerated particles. The average size of 39.5 nm, of the particles embedded inside agglomerates, was estimated by Scherer's equation. Further, UV-Vis spectroscopy was used to estimate the band gap of 2.62 eV for MCT composite thin film.

Mössbauer spectroscopy of reduced forms of a Fe-tetraphenylporphyrine complex

Directory of Open Access Journals (Sweden)

Kaczmarzyk Tomasz

2015-03-01

Full Text Available Molecular and electronic structure changes during successive reduction of a Fe-tetraphenylporphyrin chloride [Fe(III(TPP:Cl] complex are reported on the basis of Mössbauer spectroscopy and DFT calculations. It is established that the attachment of additional electrons to a neutral Fe(III(TPP:Cl molecule leads to significant shortening of Fe-N distances at the first stage of the reduction Fe(III(TPP:Cl → Fe(II(TPP and lengthening of these bonds at the second stage Fe(II(TPP → Fe(I(TPP. Changes of other bond lengths of the porphyrin ring also appear but in less degree. Interaction of Fe(II and Fe(I(TPP with tetrahydrofuran (THF solvent is considered. Electron configuration of Fe(II(TPP corresponds to intermediate-spin (S = 1 state and in the case of Fe(I(TPP low-spin state (S = ½ is observed. Electron density distribution in Fe(II- and Fe(I(TPP complexes, in association with Mössbauer data, is analyzed. Good correlation between experimental and theoretical results was obtained.

Determination of descriptors for polycyclic aromatic hydrocarbons and related compounds by chromatographic methods and liquid-liquid partition in totally organic biphasic systems.

Science.gov (United States)

Ariyasena, Thiloka C; Poole, Colin F

2014-09-26

Retention factors on several columns and at various temperatures using gas chromatography and from reversed-phase liquid chromatography on a SunFire C18 column with various mobile phase compositions containing acetonitrile, methanol and tetrahydrofuran as strength adjusting solvents are combined with liquid-liquid partition coefficients in totally organic biphasic systems to calculate descriptors for 23 polycyclic aromatic hydrocarbons and eighteen related compounds of environmental interest. The use of a consistent protocol for the above measurements provides descriptors that are more self consistent for the estimation of physicochemical properties (octanol-water, air-octanol, air-water, aqueous solubility, and subcooled liquid vapor pressure). The descriptor in this report tend to have smaller values for the L and E descriptors and random differences in the B and S descriptors compared with literature sources. A simple atom fragment constant model is proposed for the estimation of descriptors from structure for polycyclic aromatic hydrocarbons. The new descriptors show no bias in the prediction of the air-water partition coefficient for polycyclic aromatic hydrocarbons unlike the literature values. Copyright © 2014 Elsevier B.V. All rights reserved.

Febuxostat-Minoxidil Salt Solvates: Crystal Structures, Characterization, Interconversion and Solubility Performance

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Li-Yang Li

2018-02-01

Full Text Available Three febuxostat-minoxidil salt solvates with acetone (ACE, tetrahydrofuran (THF and isopropanol (IPA are synthesized by solvent-assisted grinding and characterized by infrared (IR, nuclear magnetic resonance (1H-NMR, single crystal and powder X-ray diffraction (PXRD, thermogravimetry (TG and differential scanning calorimetry (DSC. These febuxostat-minoxidil salt solvates feature isostructural with the same stoichiometries (1:1:1 molecule ratio. The proton transfers from the carboxylic group of febuxostat (FEB to imino N atom of minoxidil (MIN, which forms the motif with combined R 2 2 (9 R 4 2 (8 R 2 2 (9 graph set in the three solvates. The solvents occupy the different positions related to the motif, which results in the apparent differences in PXRD patterns before/after desolvation although they are isostructures. The FEB-MIN·THF was more thermostable than FEB-MIN·ACE and FEB-MIN·IPA relative to solvent removal from DSC patterns, which is different from the results from the solvent-exchange experiments in chemical kinetics. All three salt solvates exhibit increased equilibrium solubility compared to FEB in aqueous medium.

Kerogen chemistry 5. Anhydride formation in, solvent swelling of, and loss of organics on demineralization of Kimmeridge shales

International Nuclear Information System (INIS)

Larsen, John W.; Flores, Carlos Islas

2008-01-01

The results of three short and related, but experimentally independent, studies of 4 Kimmeridge shales and their kerogens are reported. Differential scanning calorimeter (DSC) studies of the kerogens reveal that three of the four show evidence of anhydride formation when heated at 20 C/min between 50 C and 180 C. There is no regular rank dependence of anhydride formation. After solvent swelling in tetrahydrofuran (THF), extracted organics were isolated from the THF and the recovered kerogens were swollen a second time in fresh THF. The second solvent swelling ratios were slightly larger than the first because the presence of the extracts in the original THF lowers solvent activity thus reducing swelling. The shales were demineralized in the usual way except that methylene chloride was added to dissolve any organics that were liberated from the rock as a consequence of mineral dissolution. Small amounts of organics were found in the methylene chloride supporting Price and Clayton's conclusion that organics are expelled from the kerogen and are present in lacunae in the minerals. (author)

Influence of Odd and Even Alkyl Chains on Supramolecular Nanoarchitecture via Self-Assembly of Tetraphenylethylene-Based AIEgens

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Mina Salimimarand

2017-10-01

Full Text Available The Tetraphenylethylene (TPE based dumbbell shaped molecules TPE-Pi, TPE-Su, TPE-Az, and TPE-Se were synthesised bearing odd-even alkyl chains containing 7, 8, 9 and 10 carbons respectively. These molecules reveal typical Aggregation Induced Emission (AIE behaviour. The influence of the odd or even alkyl chain length was shown by studying the morphology of self-assembled nanostructures formed in a range of tetrahydrofuran (THF/water solvent systems. For example, with a water fraction of 80%, TPE derivatives with odd alkyl chains (TPE-Pi and TPE-Az self-assembled into nanosphere structures, while TPE-Su with 8 alkyl chains formed microbelts and TPE-Se with 10 alkyl chains aggregated into flower-like superstructures. These TPE derivatives also revealed interesting mechanochromic properties upon grinding, fuming and heating, which reveal the importance of molecular stacking in the crystal structure to the luminescent properties of the aggregates .The mechanochromic properties of TPE-Pi, TPE-Su, and TPE-Az were also demonstrated by the process of grounding, fuming, and heating.

1,3,4-Tri-O-acetyl-2-N-(trifluoroacetyl-β-l-fucose

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David C. McCutcheon

2014-02-01

Full Text Available The title compound, C14H18F3NO8, was produced through conjugation of 1,3,4-tri-O-acetyl-2-azidodeoxy-α,β-l-fucose with trifluoroacetyl chloride in the presence of bis(diphenylphosphinoethane in tetrahydrofuran at room temperature. The X-ray crystal structure reveals that the β-anomer of the product mixture crystallizes from ethyl acetate/hexanes. The compound exists in a typical chair conformation with the maximum possible number of substituents, four out of five, located in the sterically preferred equatorial positions. The major directional force facilitating packing of the molecules are N—H...O hydrogen bonds involving the amide moieties of neighboring molecules, which connect molecules stacked along the a-axis direction into infinite strands with a C11(4 graph-set motif. Formation of the strands is assisted by a number of weaker C—H...O interactions involving the methine and methyl H atoms. These strands are connected through further C—H...O and C—H...F interactions into a three dimensional network

Buckminsterfullerene's (C60) octanol-water partition coefficient (Kow) and aqueous solubility.

Science.gov (United States)

Jafvert, Chad T; Kulkarni, Pradnya P

2008-08-15

To assess the risk and fate of fullerene C60 in the environment, its water solubility and partition coefficients in various systems are useful. In this study, the log Kow of C60 was measured to be 6.67, and the toluene-water partition coefficient was measured at log Ktw = 8.44. From these values and the respective solubilities of C60 in water-saturated octanol and water-saturated toluene, C60's aqueous solubility was calculated at 7.96 ng/L(1.11 x 10(-11) M) for the organic solvent-saturated aqueous phase. Additionally, the solubility of C60 was measured in mixtures of ethanol-water and tetrahydrofuran-water and modeled with Wohl's equation to confirm the accuracy of the calculated solubility value. Results of a generator column experiment strongly support the hypothesis that clusters form at aqueous concentrations below or near this calculated solubility. The Kow value is compared to those of other hydrophobic organic compounds, and bioconcentration factors for C60 were estimated on the basis of Kow.

RP TLC-based lipophilicity assessment of some natural and synthetic coumarins

Energy Technology Data Exchange (ETDEWEB)

Rabtti, El Hadi M.A.; Natic, Maja M.; Milojkovic-Opsenica, Dusanka M.; Trifkovic, Jelena D.; Vuckovic, Ivan M.; Tesic, Zivoslav Lj., E-mail: ztesic@chem.bg.ac.rs [Faculty of Chemistry, University of Belgrade, Belgrade (Serbia); Vajs, Vlatka E. [Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Belgrade (Serbia)

2012-03-15

The lipophilic character of twelve coumarins was investigated by reversed-phase thin-layer chromatography (RP TLC) on RP-18 silica. The three different binary solvent systems composed of water and organic modifier (methanol, tetrahydrofuran or acetonitrile) were used in order to determine retention parameter (R{sub M}{sup 0}) and octanol-water partition coefficient (log P{sub OW})as a measure of the lipophilicity of the tested compounds. Lipophilicity parameter (log P{sub OW}) was experimentally determined using eight standard solutes with known log P{sub OW} values which were analyzed under the same chromatographic conditions as the target substances. Lipophilicity parameters together with 2D molecular descriptors were subjected to the multivariate statistical analysis (principal component analysis (PCA) and partial least square (PLS) regression) in order to reveal the most influential factors governing the retention, i.e., lipophilicity of the investigated compounds. The quantitative structure-retention relationship models reveal the importance of descriptors which describe the size and the shape of the molecule as well as their polar properties. (author)

Assessment of Blend PVDF Membranes, and the Effect of Polymer Concentration and Blend Composition

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Imtiaz Ali

2018-03-01

Full Text Available In this work, PVDF homopolymer was blended with PVDF-co-HFP copolymer and studied in terms of morphology, porosity, pore size, hydrophobicity, permeability, and mechanical properties. Different solvents, namely N-Methyl-2 pyrrolidone (NMP, Tetrahydrofuran (THF, and Dimethylformamide (DMF solvents, were used to fabricate blended PVDF flat sheet membranes without the introduction of any pore forming agent, through a non-solvent induced phase separation (NIPS technique. Furthermore, the performance of the fabricated membranes was investigated for pressure and thermal driven applications. The porosity of the membranes was slightly increased with the increase in the overall content of PVDF and by the inclusion of PVDF copolymer. Total PVDF content, copolymer content, and mixed-solvent have a positive effect on mechanical properties. The addition of copolymer increased the hydrophobicity when the total PVDF content was 20%. At 25% and with the inclusion of mixed-solvent, the hydrophobicity was adversely affected. The permeability of the membranes increased with the increase in the overall content of PVDF. Mixed-solvents significantly improved permeability.

Green hypergolic combination: Diethylenetriamine-based fuel and hydrogen peroxide

Science.gov (United States)

Kang, Hongjae; Kwon, Sejin

2017-08-01

The present research dealt with the concept of green hypergolic combination to replace the toxic hypergolic combinations. Hydrogen peroxide was selected as a green oxidizer. A novel recipe for the non-toxic hypergolic fuel (Stock 3) was suggested. Sodium borohydride was blended into the mixture of energetic hydrocarbon solvents as an ignition source for hypergolic ignition. The main ingredient of the mixture was diethylenetriamine. By mixing some amount of tetrahydrofuran with diethylenetriamine, the mixture became more flammable and volatile. The mixture of Stock 3 fuel remained stable for four months in the lab scale storability test. Through a simple drop test, the hypergolicity of the green hypergolic combination was verified. Comparing to the toxic hypergolic combination MMH/NTO as the reference, the theoretical performance of the green hypergolic combination would be achieved about 96.7% of the equilibrium specific impulse and about 105.7% of the density specific impulse. The applicability of the green hypergolic combination was successfully confirmed through the static hot-fire tests using 500 N scale hypergolic thruster.

Solvent Effect, Photochemical and Photophysical Properties of Phthalocyanines with Different Metallic Nuclei

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Charles Biral Silva

2017-12-01

Full Text Available Photophysical and photochemical properties of lithium phthalocyanine (1, gallium(III phthalocyanine chloride (2, titanium(IV phthalocyanine dichloride (3 and iron(II phthalocyanine (4 were investigated in dimethyl sulfoxide (DMSO, tetrahydrofuran (THF and DMSO-THF mixtures. The influence of the central metal on these properties was analyzed according to solvent type, axial ligands and their paramagnetic and diamagnetic effect. Fluorescence lifetimes were recorded using a time correlated single photon counting setup (TCSPC technique. In order to demonstrate the generation of reactive oxygen species under light irradiation, the indirect method (applying 1,3-diphenylisobenzofuran (DPBF as chemical suppressor and the direct method (analyzing the phosphorescence decay curves of singlete oxygen at 1270 nm were employed. Compounds 1, 2 and 3 showed a monomeric behavior in all media while compound 4 presented low aggregation in DMSO, but a very pronounced aggregation behavior in THF. Steady-state fluorescence anisotropy was compared with emission spectra and complex 4 presented values beyond the expected limits. DOI: http://dx.doi.org/10.17807/orbital.v9i5.1047 

Assessment of Blend PVDF Membranes, and the Effect of Polymer Concentration and Blend Composition.

Science.gov (United States)

Ali, Imtiaz; Bamaga, Omar A; Gzara, Lassaad; Bassyouni, M; Abdel-Aziz, M H; Soliman, M F; Drioli, Enrico; Albeirutty, Mohammed

2018-03-05

In this work, PVDF homopolymer was blended with PVDF-co-HFP copolymer and studied in terms of morphology, porosity, pore size, hydrophobicity, permeability, and mechanical properties. Different solvents, namely N-Methyl-2 pyrrolidone (NMP), Tetrahydrofuran (THF), and Dimethylformamide (DMF) solvents, were used to fabricate blended PVDF flat sheet membranes without the introduction of any pore forming agent, through a non-solvent induced phase separation (NIPS) technique. Furthermore, the performance of the fabricated membranes was investigated for pressure and thermal driven applications. The porosity of the membranes was slightly increased with the increase in the overall content of PVDF and by the inclusion of PVDF copolymer. Total PVDF content, copolymer content, and mixed-solvent have a positive effect on mechanical properties. The addition of copolymer increased the hydrophobicity when the total PVDF content was 20%. At 25% and with the inclusion of mixed-solvent, the hydrophobicity was adversely affected. The permeability of the membranes increased with the increase in the overall content of PVDF. Mixed-solvents significantly improved permeability.

Viscometric investigation of compatibilization of the poly(vinyl chloride)/poly(ethylene-co-vinyl acetate) blends by terpolymer of maleic anhydride styrene vinyl acetate

Science.gov (United States)

İmren, Dilek; Boztuğ, Ali; Yılmaz, Ersen; Zengin, H. Bayram

2008-11-01

In this study, a blend of poly(vinyl chloride) (PVC)/ethylene-co-vinyl acetate (EVA) was compatibilized by terpolymer of maleic anhydride-styrene-vinyl acetate (MAStVA) used as a compatibilizer. It was prepared the blends of 50/50 PVC/EVA containing 2-10% of the terpolymer. The compatibility experiences of these blends were investigated by using viscometric method in the range of concentrations (0.5-2.0 g dL -1) where tetrahydrofuran (THF) is the solvent. The interaction parameter (Δ b) was used to study the miscibility and compatibility of polymer blend in solution, obtained from the modified Krigbaum and Wall theory. Turbidity and FTIR measurements were also used to investigate the miscibility of this pair of polymers. The values of the relative viscosities of the each polymer solution and their blends were measured by a Cannon-Fenske type viscometer. In consequence of the study, it was observed that a considerable improvement was achieved in the miscibility of PVC/EVA blends by adding among 5 and 10 wt% of compatibilizer.

Solution Construction of Multigeometry Nanoparticles and Multicompartment Superstructures from Block Copolymer Mixtures

Science.gov (United States)

Zhu, Jiahua; Zhang, Shiyi; Wooley, Karen; Pochan, Darrin

2013-03-01

Novel soft objects with both compositional and geometric complexity at nanoscale have been constructed through solution supramolecular assembly from block copolymer mixtures due to their non-ergodic character. The mixture is composed of two block copolymers with distinctive hydrophobic blocks but the same poly(acrylic acid) hydrophilic block. First, multigeometry nanoparticles, due to segregation of unlike block copolymer molecules into multiple subdomains trapped within the same micelle-like structures, have been assembled in tetrahydrofuran/water solution. Through carefully designed molecular architecture, mixing ratio and pathway kinetics, both size and shape of subdomains can be controlled to produce a novel class of multigeometry nanoparticles, including sphere-sphere, sphere-cylinder, cylinder-cylinder, cylinder-disk, and sphere-disk hybrid nanoparticles. Second, hierarchical multicompartment superstructures including particle chains, rings and other nano to micro cluster formations, have been built up from pre-formed multigeometry nanoparticles by taking advantage of their surface anisotropy and the controlled particle-particle association. The interparticle association can be achieved via either covalent or non-covalent bindings due to different post-polymerization chemical modifications with hydroxyethyl acrylate or crown ether functionalities, respectively.

Preparation and characterization of rubbery epoxy/multiwall carbon nanotubes composites using amino acid salt assisted dispersion technique

Directory of Open Access Journals (Sweden)

S. B. Jagtap

2013-04-01

Full Text Available Epoxy/multiwall carbon nanotubes (MWCNT composites were prepared using sodium salt of 6-aminohexanoic acid (SAHA modified MWCNT and its effect properties of related composites were investigated. The composite prepared using a polar solvent, tetrahydrofuran exhibits better mechanical properties compared to those prepared using less polar solvent and without using solvent. The tensile properties and dynamic storage modulus was found to be increased as a result of modification of MWCNT with SAHA. This improvement in the tensile properties and dynamic mechanical properties of epoxy/MWCNT composite is a combined effect of cation-π interaction and chemical bonding. Fourier transform infrared spectroscopy (FTIR and Raman spectroscopy were used to explain cation-π interaction between SAHA with MWCNT and chemical bonding of SAHA with epoxy resin. The effect of modification of MWCNT on morphology of a nanocomposite was confirmed by using scanning electron microscopy (SEM and transmission electron microscopy (TEM. The present approach does not disturb the ! electron clouds of MWCNT as opposed to chemical functionalization strategy.

Synthesis, properties, and assimilation methods of aluminium hydride

International Nuclear Information System (INIS)

Mirsaidov, U.M.

2013-01-01

We have discovered a new source of aluminium hydride-conversion of tetrahydrofurane under influence of halogenous alkyls. We have proposed the chlorbenzene method of synthesis of AlH 3 , which excludes adhesion and ensure high quality of the product with respect to its purity, thermal stability, habits of crystals (round shape), and granulometric composition. We determined capability of benzyl chloride to fix AlH 4 -groups by the way of complexes formation. This allows increasing efficient concentration of AlH 3 solutions and their productivity. We have carried out 'direct' crystallization of aluminium hydride in one stage using interaction of binary metal hydride with aluminium chloride in the medium of ether-toluene at 60-100 d ig C a nd using solvent distillation. In the reaction of Li H with AlCl 3 , we achieved output of pure crystal AlH 3 of hexagonal modification, which was close to quantitative. We have discovered the assimilation methods of aluminium hydride in carrying out of solid-phase chemical reactions. (author)

Suppression of Protonated Organic Solvents in NMR Spectroscopy Using a Perfect Echo Low-Pass Filtration Pulse Sequence.

Science.gov (United States)

Howe, Peter W A

2018-04-03

Proton NMR spectra are usually acquired using deuterated solvents, but in many cases it is necessary to obtain spectra on samples in protonated solvents. In these cases, the intense resonances of the protonated solvents need to be suppressed to maximize sensitivity and spectral quality. A wide range of highly effective solvent suppression methods have been developed, but additional measures are needed to suppress the 13 C satellites of the solvent. Because the satellites represent 1.1% of the original solvent signal, they remain problematic if unsuppressed. The recently proposed DISPEL pulse sequences suppress 13 C satellites extremely effectively, and this Technical Note demonstrates that combining DISPEL and presaturation results in exceptionally effective solvent suppression. An important element in the effectiveness is volume selection, which is inherent within the DISPEL sequence. Spectra acquired in protonated dimethlysulfoxide and tetrahydrofuran show that optimum results are obtained by modifying the phase cycle, cycling the pulse-field gradients, and using broadband 13 C inversion pulses to reduce the effects of radiofrequency offset and inhomogeneity.

Carbon nanofibers extracted from soot as a sorbent for the determination of aromatic amines from wastewater effluent samples.

Science.gov (United States)

Vadukumpully, Sajini; Basheer, Chanbasha; Jeng, Cheng Suh; Valiyaveettil, Suresh

2011-06-10

The isolation and characterization of carbon nanofibers from soot obtained by burning natural oil is reported. The fibers were extracted from the soot with tetrahydrofuran followed by sonication. The carbon nanofibers were mixed with poly(vinyl alcohol) and electrospun to get the nanofiber mat. The extraction ability of electrospun nanofibers for the separation and preconcentration of aromatic compounds such as 3-nitroaniline, 4-chloroaniline, 4-bromoaniline and 3,4-dichloroaniline were tested and efficiently evaluated using high performance liquid chromatography. Under optimized conditions, the method showed good linearity in a range of 0.5-50 μg L⁻¹ with correlation coefficient ranging from 0.989 to 0.998. High precision of the extraction with RSD values of 4.5-5.8% and low LOD value in a range of 0.009-0.081μg L⁻¹ for all aniline compounds were achieved. The proposed microextraction method offers advantages such as easy operation, high recovery, fast extraction, minimal use of organic solvent and elimination of tedious solvent evaporation and reconstitution steps. Copyright © 2011 Elsevier B.V. All rights reserved.

Changing the Mechanism for CO ₂ Hydrogenation Using Solvent-Dependent Thermodynamics

Energy Technology Data Exchange (ETDEWEB)

Burgess, Samantha A. [Catalysis Science Group, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Appel, Aaron M. [Catalysis Science Group, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Linehan, John C. [Catalysis Science Group, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Wiedner, Eric S. [Catalysis Science Group, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA

2017-10-23

A critical scientific challenge for utilization of CO2 is the development of catalyst systems that do not depend upon expensive or environmentally unfriendly reagents, such as precious metals, strong organic bases, and organic solvents. We have used thermodynamic insights to predict and demonstrate that the HCoI(dmpe)2 catalyst system, previously described for use in organic solvents, can hydrogenate CO2 to formate in water with bicarbonate as the only added reagent. Replacing tetrahydrofuran as the solvent with water changes the mechanism for catalysis by altering the thermodynamics for hydride transfer to CO2 from a key dihydride intermediate. The need for a strong organic base was eliminated by performing catalysis in water due to the change in mechanism. These studies demonstrate that the solvent plays a pivotal role in determining the reaction thermodynamics and thereby catalytic mechanism and activity. The research was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.

Exploration and characterization of new synthesis methods for C60 colloidal suspensions in water

Science.gov (United States)

Hilburn, Martha E.

Buckminsterfullerene, C60, has been used in the production of several commercial products from badminton racquets and lubricants for their mechanical properties to cosmetics and even dietary supplements for their "antioxidant" properties. Multi-ton production of C60 began in 2003 encouraging serious consideration of its fate in the environment in the case of an accidental release or improper disposal. Although C60 is practically insoluble in water, it readily forms stable aqueous colloidal suspensions (termed nC60) through solvent exchange methods or long-term vigorous stirring in water. Two new solvent exchange methods for synthesizing nC60 are presented. These methods combine key advantages of multiple existing synthesis methods including high yield, narrow particle size distribution, short synthesis time, and an absence of solvents such as tetrahydrofuran that have historically caused problems in laboratory synthesized aggregates. The resulting samples are attractive candidates for use in controlled environmental impact, biological, and toxicity studies. An improved method for quantifying residual solvents in nC60 samples utilizing solid phase micro extraction gas chromatography mass spectrometry (SPME-GC-MS) is also discussed.

SODIUM DI-N-DODECYL PHOSPHATE VESICLES IN AQUEOUS-SOLUTION - EFFECTS OF ETHANOL, PROPANOL, AND TETRAHYDROFURAN ON THE GEL TO LIQUID-PHASE TRANSITION

NARCIS (Netherlands)

BLANDAMER, MJ; BRIGGS, B; BUTT, MD; WATERS, M; CULLIS, PM; ENGBERTS, JBFN; HOEKSTRA, D; MOHANTY, RK

1994-01-01

For aqueous solutions containing vesicles formed by sodium di-n-dodecyl phosphate, the gel to liquid-crystal transition occurs near 35 degrees C, the temperature T-m. When ethanol is added, T-m decreases, but the scan shows evidence of several transitions as more alcohol is added. The effect of

Assessing two different peroxidases´ potential for application in recalcitrant organic compound bioremediation

Directory of Open Access Journals (Sweden)

Nelson Caicedo

2001-07-01

Full Text Available This work shows the promising future presented by the following enzymes: Chloroperoxidase (CPO from Caldariomyces fumago and royal palm peroxidase (Roystonea regia, PPR. These peroxidases were obtained from different sources (microbial and vegetable and used as biocatalysts for applicating them in bioremediation of recalcitrant organic compounds. Each one of the enzymes' peroxidase catalytic activity was evaluated in organic phase systems, using different model compounds such as: PAHs (pyrene and anthracene, organic-nitrogenated compounds (diphenylamine, monoaromatic phenolic molecules (guayacol and dyes (methyl orange and ABTS. The reaction systems were composed of mono-phase water mixtures and organic miscible solvent (methanol, ethanol, isopropanol, acetonitrile, tetrahydrofuran, dimethyl sulfoxide and dimethyl formamide, on which both peroxidases' catalytic activity was evaluated. The two enzymes' catalytic activity was observed on the evaluated substrates in most of these assays. However, PPR did not show biocatalytic oxidation for methyl orange dye and some PAHs. This enzyme did show the best tolerance to the evaluated solvents. Its catalytic activity was appreciably enhanced when low hydrophobic solvents were used. The kcat was calculated from this experimental data (as kinetic parameter leading to each enzyme's biocatalytic performance on substrates being compared.

Solvent effects on polymer sorting of carbon nanotubes with applications in printed electronics.

Science.gov (United States)

Wang, Huiliang; Hsieh, Bing; Jiménez-Osés, Gonzalo; Liu, Peng; Tassone, Christopher J; Diao, Ying; Lei, Ting; Houk, Kendall N; Bao, Zhenan

2015-01-07

Regioregular poly(3-alkylthiophene) (P3AT) polymers have been previously reported for the selective, high-yield dispersion of semiconducting single-walled carbon nanotubes (SWCNTs) in toluene. Here, five alternative solvents are investigated, namely, tetrahydrofuran, decalin, tetralin, m-xylene, and o-xylene, for the dispersion of SWCNTs by poly(3-dodecylthiophene) P3DDT. The dispersion yield could be increased to over 40% using decalin or o-xylene as the solvents while maintaining high selectivity towards semiconducting SWCNTs. Molecular dynamics (MD) simulations in explicit solvents are used to explain the improved sorting yield. In addition, a general mechanism is proposed to explain the selective dispersion of semiconducting SWCNTs by conjugated polymers. The possibility to perform selective sorting of semiconducting SWCNTs using various solvents provides a greater diversity of semiconducting SWCNT ink properties, such as boiling point, viscosity, and surface tension as well as toxicity. The efficacy of these new semiconducting SWCNT inks is demonstrated by using the high boiling point and high viscosity solvent tetralin for inkjet-printed transistors, where solvent properties are more compatible with the inkjet printing head and improved droplet formation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of Low Energy Gap and Fully Regioregular Polythienylenevinylene Derivative

Directory of Open Access Journals (Sweden)

Tanya M. S. David

2014-01-01

Full Text Available Low energy gap and fully regioregular conjugated polymers find its wide use in solar energy conversion applications. This paper will first briefly review this type of polymers and also report synthesis and characterization of a specific example new polymer, a low energy gap, fully regioregular, terminal functionalized, and processable conjugated polymer poly-(3-dodecyloxy-2,5-thienylene vinylene or PDDTV. The polymer exhibited an optical energy gap of 1.46 eV based on the UV-vis-NIR absorption spectrum. The electrochemically measured highest occupied molecular orbital (HOMO level is −4.79 eV, resulting in the lowest unoccupied molecular orbital (LUMO level of −3.33 eV based on optical energy gap. The polymer was synthesized via Horner-Emmons condensation and is fairly soluble in common organic solvents such as tetrahydrofuran and chloroform with gentle heating. DSC showed two endothermic peaks at 67°C and 227°C that can be attributed to transitions between crystalline and liquid states. The polymer is thermally stable up to about 300°C. This polymer appears very promising for cost-effective solar cell applications.

Total cross section of furfural by electron impact: Experiment and theory

Science.gov (United States)

Traoré Dubuis, A.; Verkhovtsev, A.; Ellis-Gibbings, L.; Krupa, K.; Blanco, F.; Jones, D. B.; Brunger, M. J.; García, G.

2017-08-01

We present experimental total cross sections for electron scattering from furfural in the energy range from 10 to 1000 eV, as measured using a double electrostatic analyzer gas cell electron transmission experiment. These results are compared to theoretical data for furfural, as well as to experimental and theoretical values for the structurally similar molecules furan and tetrahydrofuran. The measured total cross section is in agreement with the theoretical results obtained by means of the independent-atom model with screening corrected additivity rule including interference method. In the region of higher electron energies, from 500 eV to 10 keV, the total electron scattering cross section is also estimated using a semi-empirical model based on the number of electrons and dipole polarizabilities of the molecular targets. Together with the recently measured differential and integral cross sections, and the furfural energy-loss spectra, the present total cross section data nearly complete the data set that is required for numerical simulation of low-energy electron processes in furfural, covering the range of projectile energies from a few electron volts up to 10 keV.

Novel hydrophobic PDVB/R-SiO2 for adsorption of volatile organic compounds from highly humid gas stream.

Science.gov (United States)

Lu, Han-feng; Cao, Jie-jing; Zhou, Ying; Zhan, De-li; Chen, Yin-fei

2013-11-15

A novel organic-inorganic hydrophobic polydivinylbenzene-silica adsorbent (PDVB/R-SiO2) was successfully prepared by introducing a specific amount of divinylbenzene and solvent (i.e., tetrahydrofuran) to SiO2pores and initiating polymerization under solvothermal conditions. New smaller structures and surface areas were formed in the SiO2 pores. The PDVB/R-SiO2-0.5 samples exhibited a bimodal pore size distribution with both SiO2 micropores/mesopores (0.5-2.0 nm) and mesopores (2.0-5.0 nm). The surface areas increased from 116 m(2)/g (SiO2) to 246 m(2)/g. The breakthrough curves of toluene adsorption indicated that the amount adsorbed on PDVB/R-SiO2-0.5 was 12 times higher than that on SiO2. The highly humid environment exhibited no effect on adsorption because the surface of PDVB was functionalized. The adsorbed toluene was easily desorbed in hot N2 stream at 100 °C. After 10 adsorption-desorption cycles, PDVB/R-SiO2-0.5 continued exhibiting excellent adsorption, indicating superior structural and regeneration abilities. Copyright © 2013 Elsevier B.V. All rights reserved.

Effects of basic nitrogen poisoning on adsorption of hydrogen on a hydrotreatment catalyst

International Nuclear Information System (INIS)

Entz, R.W.; Seapan, M.

1985-01-01

Activity of a hydrotreatment catalyst depends on the hydrogen adsorption characteristics of the catalyst. In this work, the adsorption of hydrogen on a Ni-Mo/Al/sub 2/O/sub 3/ catalyst (shell 324) has been studied using a TGA at 1 atm pressure and 200-400 0 C temperature. Hydrogen adsorption on a calcined catalyst was shown to be of activated type with a sudden increase in hydrogen adsorption around 350 0 C. When the catalyst is extracted with Tetrahydrofuran (THF), the hydrogen adsorption increases gradually as the temperature is increased, approaching a monolayer coverage of the catalyst surface. It is shown that solvent extraction of catalyst changes its hydrogen adsorption characteristics significantly. Indeed, at 400 0 C, an extracted catalyst adsorbs about four times more hydrogen than an unextracted catalyst. Adsorption of basic nitrogen compounds on the catalyst interferes with the hydrogen adsorption. The adsorption of pyridine, piperidine, n-pentylamine, and ammonia were studied at 400 0 C. It is shown that the strength of adsorption of piperidine and n-pentylamine are relatively similar, however their adsorption strength is higher than pyridine. Ammonia is the weakest adsorbing compound studied. These observations are in agreement with other studies

Deuterium isotope fractionation between ortho-alkyl substituted phenols and t-butylthiol in oxygen bases

International Nuclear Information System (INIS)

Wawer, A.; Jelenska-Kazimierczuk, M.; Szydlowski, J.

1998-01-01

Equilibrium isotope effect in the exchange reaction of deuterium between phenol(P), 2-isopropyl phenol (IPP), 2,6-diisopropyl phenol (DIPP), 2,6-diterbutyl phenol (DTBP) and tertbutylthiol (TBT) has been studied in 296 K. The fractionation factors (α) have been measured in cyclohexane and carbon tetrachloride solutions and in a few oxygen bases: acetone, 1,4-dioxane, ethyl formate, ethyl ether, tetrahydrofurane, N,N-dimethylformamide, dimethylsulfoxide and hexamethylphosphoramide. Using chemical shifts of phenol OH protons, the thermodynamic parameters of complex formation with the oxygen bases have been determined. The experimental data show that lnα correlates with the formation enthalpy of the phenol-oxygen base complex in DIPP-TBT-base system but there is no simple correlation in IPP-TBT-base system. Furthermore, it was found that in DTBT-TBT-base system lnα depends linearly on the basicity of the solvent (DN parameters). On the other hand, lnα correlates with acidic parameters of the solvents (AN) in IPP-TBT-base and P-TBT-base systems. All above correlations are explained by taking into account two competition processes: self association of phenol molecules and their solvation by oxygen bases. (author)

Computation-Assisted Molecularly Imprinted Polymer Synthesis for Extraction of Naltrexone from Urine Using Experimental Design and Determination by UPLC-DAD.

Science.gov (United States)

Rahmani, Mahdiyeh Ebrahimi; Ansari, Mehdi; Nateghi, Mohammadreza; Kazemipour, Maryam

2017-05-01

To design a molecularly imprinted polymer (MIP) for naltrexone, calculations were performed using Gaussian 03 software, and the interaction energy (ΔE) of template-monomer complexes was estimated using the density functional theory method with the B3LYP function and 6-311G (d) basis set. The effect of different solvents in the polymerization process was studied using the polarizable continuum model. It was shown that five molecules of methacrylic acid gave the largest ΔE with tetrahydrofuran as the polymerization solvent. Effective factors of the removal efficiency of naltrexone by the MIP were selected using a central composite design, and thereafter, the optimization of significant factors was performed by response surface methodology. The results predicted through these models showed good agreement with experimental values. The adsorption amount, selectivity distribution coefficient, and selectivity coefficient were found to be 11.60 mg/g, 35.31, and 2.27, respectively. Experiments of naltrexone adsorption onto the MIP were in accordance with the first-order and Langmuir-Freundlich adsorption models. By applying the data to the Scatchard equation, the KD and Qmax were determined as 526.31 mg/L and 19.47 mg/g, respectively.

Coal liquefaction process streams characterization and evaluation: Application of liquid chromatographic separation methods to THF-soluble portions of integrated two-stage coal liquefaction resids

Energy Technology Data Exchange (ETDEWEB)

Green, J.B.; Pearson, C.D.; Young, L.L.; Green, J.A. [National Inst. for Petroleum and Energy Research, Bartlesville, OK (United States)

1992-05-01

This study demonstrated the feasibility of using non-aqueous ion exchange liquid chromatography (NIELC) for the examination of the tetrahydrofuran (THF)-soluble distillation resids and THF-soluble whole oils derived from direct coal liquefaction. The technique can be used to separate the material into a number of acid, base, and neutral fractions. Each of the fractions obtained by NIELC was analyzed and then further fractionated by high-performance liquid chromatography (HPLC). The separation and analysis schemes are given in the accompanying report. With this approach, differences can be distinguished among samples obtained from different process streams in the liquefaction plant and among samples obtained at the same sampling location, but produced from different feed coals. HPLC was directly applied to one THF-soluble whole process oil without the NIELC preparation, with limited success. The direct HPLC technique used was directed toward the elution of the acid species into defined classes. The non-retained neutral and basic components of the oil were not analyzable by the direct HPLC method because of solubility limitations. Sample solubility is a major concern in the application of these techniques.

A fast response hafnium selective polymeric membrane electrode based on N,N'-bis({alpha}-methyl-salicylidene)-dipropylenetriamine as a neutral carrier

Energy Technology Data Exchange (ETDEWEB)

Rezaei, B. [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)], E-mail: rezaei@cc.iut.ac.ir; Meghdadi, S.; Zarandi, R. Fazel [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

2008-08-30

In this study a new hafnium selective sensor was fabricated from polyvinylchloride (PVC) matrix membrane containing neutral carrier N,N'-bis({alpha}-methyl-salicylidene)-dipropylenetriamine (Mesaldpt) as a new ionophore, sodium tetraphenyl borate (NaTPB) as anionic discriminator and dioctyl phthalate (DOP) as plasticizing solvent mediator in tetrahydrofuran solvent. The electrode exhibits Nernstian response for Hf{sup 4+} (Hafnium(IV)) over a wide concentration range (2.0 x 10{sup -7} to 1.0 x 10{sup -1} M) with the determination coefficient of 0.9966 and slope of 15.1 {+-} 0.1 mV decades{sup -1}. The limit of detection is 1.9 x 10{sup -7} M. The electrode has a fast response time of 18 s and a working pH range of 4-8. The proposed membrane shows excellent discriminating ability towards Hf{sup 4+} ion with regard to several alkali, alkaline earth transition and heavy metal ions. It can be used over a period of 1.5 months with good reproducibility. It is successfully applied for direct determination of Hf{sup 4+} in solutions by standard addition method for real sample analysis.

Study of temperature dependence and angular distribution of poly(9,9-dioctylfluorene) polymer films deposited by matrix-assisted pulsed laser evaporation (MAPLE)

International Nuclear Information System (INIS)

Caricato, A.P.; Anni, M.; Manera, M.G.; Martino, M.; Rella, R.; Romano, F.; Tunno, T.; Valerini, D.

2009-01-01

Poly(9,9-dioctylfluorene) (PFO) polymer films were deposited by matrix-assisted pulsed laser evaporation (MAPLE) technique. The polymer was diluted (0.5 wt%) in tetrahydrofuran and, once cooled to liquid nitrogen temperature, it was irradiated with a KrF excimer laser. 10,000 laser pulses were used to deposit PFO films on Si substrates at different temperatures (-16, 30, 50 and 70 deg. C). One PFO film was deposited with 16,000 laser pulses at a substrate temperature of 50 deg. C. The morphology, optical and structural properties of the films were investigated by SEM, AFM, PL and FTIR spectroscopy. SEM inspection showed different characteristic features on the film surface, like deflated balloons, droplets and entangled polymer filaments. The roughness of the films was, at least partially, controlled by substrate heating, which however had the effect to reduce the deposition rate. The increase of the laser pulse number modified the target composition and increased the surface roughness. The angular distribution of the material ejected from the target confirmed the forward ejection of the target material. PFO films presented negligible modification of the chemical structure respect to the bulk material.

Effect of Piper betle on Giardia intestinalis infection in vivo.

Science.gov (United States)

Pecková, Radka; Doležal, Karel; Sak, Bohumil; Květoňová, Dana; Kváč, Martin; Nurcahyo, Wisnu; Foitová, Ivona

2018-01-01

Piper betle has been used as a medicinal plant in traditional medical systems throughout South and South East Asia. Experimental studies have revealed its wide and diverse biological and pharmacological effects. In this study, antigiardial activity of Piper betle was tested using experimental infections of Giardia intestinalis, the most common cause of protozoal diarrhoea worldwide, in Mongolian gerbils. Plants were extracted in water, methanol and methanol:tetrahydrofuran. Gerbils were treated for ten days intragastrically twice a day, with the dose of 40 mg of the extract per 100 g of body weight. Drug metronidazole was used as a negative control. Gerbils' faeces were taken every day and examined by flotation method, the number of shed cysts were counted using a haemocytometer. After gerbils' sacrifice and dissection, their duodena were then processed for examination using histological sectioning and scanning electron microscopy. The antigiardial activity was evaluated by the course of cyst shedding throughout the entire experiment. A significant decline in cyst shedding, evaluated by linear regression was found in gerbils treated with the aqueous extract. Our results indicate that the aqueous extract of P. betle shows giardicidal effects. Copyright © 2017 Elsevier Inc. All rights reserved.

Pressure effect of the 1H NMR spectra of organic compounds in the presence of lanthanide shift reagents. A formally associative process characterized by volume expansion

International Nuclear Information System (INIS)

Schulman, E.M.; Cheung, C.K.; Merbach, A.E.; Yamada, H.; le Noble, W.J.

1987-01-01

Following the successful application of hydrostatic pressure in mechanistic investigations of organic reactions, chemists have launched a vigorous effort to apply this tool to substitution reactions of coordination compounds. The authors began to study pressure effects in the NMR spectra of keton-lanthanide combination with the hope that the increase shifts anticipated might enhance the utility of the method, perhaps even expand its applicability to new classes of compounds. 5-Phenyl- and 5-tert-butyladamantan-2-one, piperidine, tetrahydrofuran, and cyclopentanol exhibited pressure-reduced lanthanide-induced shifts with Eu(fod) 3 ; Yb(fob) 3 and the shielding reagent Pr(fod) 3 showed the same effect with adamantanone. Solvent variations (CD 2 Cl 2 , CCl 4 ) caused minor changes in the magnitude of these shifts but did not reverse any. With the objective of learning whether these effects are due to a suppressed equilibrium population or to a reduction in the bound shift of the complex, they measured the spectra for a series or equimolar solutions of adamantanone and Eu(fod) 3 in CDCl 3 and used the Bouquant-Chuche equation to calculate both. Reasonable agreement with known atmosphere pressure data was obtained

Seed oil triglyceride profiling of thirty-two hybrid grape varieties.

Science.gov (United States)

De Marchi, Fabiola; Seraglia, Roberta; Molin, Laura; Traldi, Pietro; De Rosso, Mirko; Panighel, Annarita; Dalla Vedova, Antonio; Gardiman, Massimo; Giust, Mirella; Flamini, Riccardo

2012-09-01

Triglyceride profile of seed oil samples from 32 hybrid grape varieties not studied before was investigated. A new method for the analysis of triacylglycerols (TAGs) has been developed based on the direct infusion in the electrospray ionization (ESI) source and employing tetrahydrofuran/methanol/water (85:10:5 v|v|v) as solvent; the formation of [M + Na](+) ions in high yield has been observed. TAGs were identified by ESI-tandem mass spectrometry analysis, and the matrix-assisted-laser-desorption-ionization and time-of-flight profile of samples was determined. Six were the principal TAGs identified in seed oil: trilinolein (LLL) was the most abundant (43%), followed by dilinoleoyl-oleoylglycerol (LOL, 23%), and dilinoleoyl-palmitoylglycerol (LPL, 15%). Compounds present in lower concentration were LSL and LOO (11%), LOP (6%), and LSP (2%). Compared with seed oils produced from V. Vinifera grapes, some significant differences in the relative abundances of TAGs were found, in particular hybrid grape seed oils showed higher LOL and lower LPL content, respectively. Among the samples studied, a particularly high content of LLL (rich in unsaturated fatty acids) was found in seed oils from two red varieties. Copyright © 2012 John Wiley & Sons, Ltd.

[6-chloro-3-pyridylmethyl-{sup 3}H]neonicotinoids as high-affinity radioligands for the nicotinic acetylcholine receptor: preparation using NaB{sup 3}H{sub 4} and LiB{sup 3}H{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Latli, Bachir; Casida, J.E. [California Univ., Berkeley, CA (United States). Dept. of Environmental Science Policy and Management; Chit Than; Morimoto, Hiromi; Williams, P.G. [Lawrence Berkeley National Lab., CA (United States)

1996-11-01

NaB{sup 3}H{sub 4} and LiB{sup 3}H{sub 4} at 78% and 97% isotopic enrichments, respectively, were used in the synthesis of {sup 3}H-labeled 1-(6-chloro-3-pyridyl)-methyl-2-nitromethyleneimidazolidine (CH-IMI) and N`-[(6-chloro-3-pyridyl)methyl]-n``-cyano-n`-methylacetamidine (acetamiprid) (two very potent insecticides) and of 1-(6-chloro-3-pyridyl)methyl-2-iminoimidazolidine (desnitro-IMI) (a metabolite of the commercial insecticides imidacloprid). 6-Chloronicotinoyl chloride was treated with either NaB{sup 3}H{sub 4} in methanol or LiB{sup 3}H{sub 4} in tetrahydrofuran and the resulting alcohol transformed to 2-chloro-5-chloromethylpyridine, which was then coupled to N-cyano-N`-methylacetamidine to give [{sup 3}H] acetamiprid (45 Ci/mmol). 2-Chloro-5-chloro[{sup 3}H]methylpyridine was also reacted with ethylenediamine and the product was either refluxed in absolute ethanol with 1,1-bis(methylthio)-2-nitro-ethylene to provide [{sup 3}H]CH-IMI or reacted in toluene with a solution of cyanogen bromide to produce [{sup 3}H] desnitro-IMI (each 55 Ci/mmol). (author).

Mechanism of the palladium-catalyzed hydrothiolation of alkynes to thioethers: a DFT study.

Science.gov (United States)

Zhang, Xing-hui; Geng, Zhi-yuan; Wang, Ke-tai; Li, Shan-shan

2014-09-01

The mechanisms of the palladium-catalyzed hydrothiolation of alkynes with thiols were investigated using density functional theory at the B3LYP/6-31G(d, p) (SDD for Pd) level. Solvent effects on these reactions were explored using the polarizable continuum model (PCM) for the solvent tetrahydrofuran (THF). Markovnikov-type vinyl sulfides or cis-configured anti-Markovnikov-type products were formed by three possible pathways. Our calculation results suggested the following: (1) the first step of the cycle is a proton-transfer process from thiols onto the palladium atom to form a palladium-thiolate intermediate. The palladium-thiolate species is attacked on alkynes to obtain an elimination product, liberating the catalyst. (2) The higher activation energies for the alkyne into the palladium-thiolate bond indicate that this step is the rate-determining step. The Markovnikov-type vinyl sulfide product is favored. However, for the aromatic alkyne, the cis-configured anti-Markovnikov-type product is favored. (3) The activation energy would reduce when thiols are substituted with an aromatic group. Our calculated results are consistent with the experimental observations of Frech and colleagues for the palladium-catalyzed hydrothiolation of alkynes to thiols.

High performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry for V and Ni quantification as tetrapyrroles

Science.gov (United States)

Duyck, Christiane Béatrice; Saint'Pierre, Tatiana Dillenburg; Miekeley, Norbert; da Fonseca, Teresa Cristina Oliveira; Szatmari, Peter

2011-05-01

A method was developed for the determination of V and Ni as tetrapyrroles by High Performance Liquid Chromatography hyphenated to Inductively Coupled Plasma Mass Spectrometry (HPLC-ICP-MS) using reversed phase and elution gradient. Chlorinated solvents and tetrahydrofuran were investigated as regard to separation time and ICP-MS detection efficiencies. The final elution gradient program started from pure methanol to a mixture of 20:80 (v/v) chloroform:methanol. External quantification of V and Ni with inorganic standards by flow injection ICP-MS, used online with HPLC, resulted in 95% of recoveries. The Limits of Detection for V during methanol elution and for Ni during the 20% chloroform gradient elution were evaluated by their minimum detectable concentrations, which were, respectively, 5 μg L - 1 and 8 μg L - 1 . The methodology was applied to polar and resin fractions separated from a Brazilian crude oil and a sediment extract from an oil-polluted area in the Guanabara Bay, Rio de Janeiro, Brazil. Vanadium as tetrapyrroles represented the totality of V content in the polar fraction, whereas Ni was in different polar forms in the resin and sediment extract.

Total cross section of furfural by electron impact: Experiment and theory.

Science.gov (United States)

Traoré Dubuis, A; Verkhovtsev, A; Ellis-Gibbings, L; Krupa, K; Blanco, F; Jones, D B; Brunger, M J; García, G

2017-08-07

We present experimental total cross sections for electron scattering from furfural in the energy range from 10 to 1000 eV, as measured using a double electrostatic analyzer gas cell electron transmission experiment. These results are compared to theoretical data for furfural, as well as to experimental and theoretical values for the structurally similar molecules furan and tetrahydrofuran. The measured total cross section is in agreement with the theoretical results obtained by means of the independent-atom model with screening corrected additivity rule including interference method. In the region of higher electron energies, from 500 eV to 10 keV, the total electron scattering cross section is also estimated using a semi-empirical model based on the number of electrons and dipole polarizabilities of the molecular targets. Together with the recently measured differential and integral cross sections, and the furfural energy-loss spectra, the present total cross section data nearly complete the data set that is required for numerical simulation of low-energy electron processes in furfural, covering the range of projectile energies from a few electron volts up to 10 keV.

Photoluminescence behavior of riboflavin and lumiflavin in liquid solutions and solid films

Energy Technology Data Exchange (ETDEWEB)

Penzkofer, A., E-mail: alfons.penzkofer@physik.uni-regensburg.de [Fakultaet fuer Physik, Universitaet Regensburg, Universitaetsstrasse 31, D-93053 Regensburg (Germany)

2012-05-25

Highlights: Black-Right-Pointing-Pointer Delayed fluorescence and phosphorescence spectra of flavins in starch films measured. Black-Right-Pointing-Pointer Quantum yield of singlet-triplet intersystem determined with a new approach. Black-Right-Pointing-Pointer Theory developed for determination of luminescence quantum yields of films. Black-Right-Pointing-Pointer Delayed fluorescence and phosphorescence lifetimes of flavins in starch films measured. Black-Right-Pointing-Pointer Singlet and triplet relevant parameters of riboflavin and lumiflavin determined. - Abstract: The absorption and emission behavior of riboflavin and lumiflavin in water, tetrahydrofuran (THF), water-starch, THF-polystyrene, starch films, and polystyrene films was studied at room temperature. Absorption cross-section spectra, fluorescence quantum distributions, and fluorescence quantum yields were determined. For the starch films additionally phosphorescence and delayed fluorescence spectra as well as phosphorescence lifetimes and delayed fluorescence lifetimes were measured and their quantum yields of intersystem-crossing, intrinsic triplet-based phosphorescence quantum yields, T{sub 1}-S{sub 0} radiative lifetimes, and S{sub 0}-T{sub 1} absorption strengths were calculated. A method of absolute intrinsic luminescence quantum distribution and quantum yield determination for dye doped films on transparent plates with a fluorimeter is described.

Ionic liquids as entrainers for water + ethanol, water + 2-propanol, and water + THF systems: A quantum chemical approach

Energy Technology Data Exchange (ETDEWEB)

Verma, Vijay Kumar [Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781 039, Assam (India); Banerjee, Tamal, E-mail: tamalb@iitg.ernet.i [Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781 039, Assam (India)

2010-07-15

Ionic liquids (ILs) are used as entrainers in azeotropic systems such as water + ethanol, water + 2-propanol, and water + tetrahydrofuran (THF). Ionic liquids consisting of a cation and an anion has limitless combinations, thereby making experimentation expensive and time taking. For the prediction of the liquid phase nonidealities resulting from molecular interactions, 'COnductor-like Screening MOdel for Real Solvents' (COSMO-RS) approach is used in this work for the screening of potential ionic liquids. Initially benchmarking has been done on 12 reported isobaric IL based ternary systems with an absolute average deviation of 4.63% in vapor phase mole fraction and 1.07% in temperature. After successful benchmarking, ternary vapor + liquid equilibria for the azeotropic mixture of (a) ethanol + water, (b) 2-propanol + water, and (c) THF + water with combinations involving 10 cations (imidazolium, pyridinium, quinolium) and 24 anions were predicted. The VLE prediction, which gave the relative volatility, showed that the imidazolium based ionic liquid were the best entrainer for the separation of the three systems at their azeotropic point. ILs with [MMIM] cation in combination with acetate [OAc], chloride [Cl], and bromide [Br] anion gave the highest relative volatility.

Estimating thermal diffusivity and specific heat from needle probe thermal conductivity data

Science.gov (United States)

Waite, W.F.; Gilbert, L.Y.; Winters, W.J.; Mason, D.H.

2006-01-01

Thermal diffusivity and specific heat can be estimated from thermal conductivity measurements made using a standard needle probe and a suitably high data acquisition rate. Thermal properties are calculated from the measured temperature change in a sample subjected to heating by a needle probe. Accurate thermal conductivity measurements are obtained from a linear fit to many tens or hundreds of temperature change data points. In contrast, thermal diffusivity calculations require a nonlinear fit to the measured temperature change occurring in the first few tenths of a second of the measurement, resulting in a lower accuracy than that obtained for thermal conductivity. Specific heat is calculated from the ratio of thermal conductivity to diffusivity, and thus can have an uncertainty no better than that of the diffusivity estimate. Our thermal conductivity measurements of ice Ih and of tetrahydrofuran (THF) hydrate, made using a 1.6 mm outer diameter needle probe and a data acquisition rate of 18.2 pointss, agree with published results. Our thermal diffusivity and specific heat results reproduce published results within 25% for ice Ih and 3% for THF hydrate. ?? 2006 American Institute of Physics.

A new potentiometric method for the estimation of the rare earth elements

International Nuclear Information System (INIS)

Selig, W.S.

1988-01-01

Chinese workers recently described a new potentiometric method for lead using sodium tetraphenylborate (NaTPB) as a titrant. Based on a previous Chinese publication, the authors have recently developed a method for the estimation of the alkaline earth metals by sequential titration with NaTPB. In the present work, the authors report a similar method for the estimation of the rare earth elements, including Sc and Y. The sensing electrode is a spectrographic graphite rod, coated with a solution of poly(vinyl chloride) and dioctylphthalate in tetrahydrofuran as previously described. The reference electrode was a double-junction Ag/AgCl electrode. The titration system is controlled by a Tektronix 4051 graphics computer system. Single cations or mixtures up to 0.5 mequiv are determined by potentiometric titration with 0.05 N NaTPB, after formation of the oxonium cations by reaction with an aqueous solution of poly(ethylene glycol) (PEG). Best results are obtained with PEGs of molecular weights from 8,000 to 20,000. Sequential estimation of Pb + Ba, Sr, and Ca, and the sum of the rare earth elements is also reported, plus possible applications to Al, Ga, and anions precipitated by lead

The effect of host relaxation and dynamics on guest molecule dynamics in H2/tetrahydrofuranhydrate.

Science.gov (United States)

Peterson, Vanessa K; Shoko, Elvis; Kearley, Gordon J

2011-01-01

We use ab initio molecular dynamics simulations to obtain classically the effects of H2O cage motions on the potential-energy surface (PES) of encapsulated H2 in the H2/tetrahydrofuran-hydrate system. The significant differences between the PES for the H2 in rigid and flexible cages that we find will influence calculation of the quantum dynamics of the H2. Part of these differences arises from the relaxation of the H2O cage around the classical H2, with a second part arising from the coupling of both translational and rotational motions of H2 with the H20 cage. We find that isotopic substitution of 2H for 1H of the H2O cage affects the coupling, which has implications for experiments that require the use of 2H2O, including inelastic neutron scattering that uses 2H2O cages in order to focus on the H2 guest dynamics. Overall, this work emphasizes the importance of taking into account cage dynamics in any approach used to understand the dynamics of H2 guests in porous framework materials.

Development and validation of a fast RP-HPLC method for determination of methotrexate entrapment efficiency in polymeric nanocapsules.

Science.gov (United States)

Sartori, Tatiane; Seigi Murakami, Fabio; Pinheiro Cruz, Ariane; Machado de Campos, Angela

2008-07-01

A rapid and effective isocratic chromatographic procedure is successfully developed to determinate methotrexate (MTX) entrapment efficiency (EE) in polymeric nanocapsules using reversed-phase high-performance liquid chromatography. The method employed a RP-C(18) Shimadzu Shim-pack CLC-ODS (150 mm x 4.6 mm, 5 microm) column with mobile phase constituted by a mixture of water-acetonitrile-tetrahydrofuran (65:30:5 v/v/v; pH 3.0) at a flow rate of 0.8 mL/min. The eluate is monitored with a UV detector set at 313 nm. The parameters used in the validation process are: linearity, specificity, precision, accuracy, and limit of quantitation (LOQ). The linearity is evaluated by a calibration curve in the concentration range of 10-50 microg/mL and presented a correlation coefficient of 0.9998. The polymers (PLA or PLA-PEG), oil, and surfactants used in the nanocapsule formulation did not interfere with analysis and the recovery was quantitative. The intra and inter-day assay relative standard deviation were less than 0.72%. Results are satisfactory, and the method proved to be adequate for the determination of methotrexate in nanocapsules formulations.

Volatile production during preignition heating. Final technical report, 15 September 1980-30 September 1982

Energy Technology Data Exchange (ETDEWEB)

Ballantyne, A.; Chou, H.; Flusberg, A.; Neoh, K.; Orozco, N.; Stickler, D.

1983-10-01

Pulverized coal particles, in a flowing inert nitrogen stream, have been heated by high power Carbon Dioxide Laser. The consequence of such an irradiation have proved to be both novel and surprising as a result of the rapid quenching of primary coal products. It ahs been found that the gas phase yield from such heating (typically, temperatures in excess of 1400 K at rates approx. 2 x 10/sup 5/ K/s) is very small (< 0.2 percent of coal carbon and hydrogen). Analysis of the solid residue has shown the presence of fine lacy particulate chains of material of 0.1 ..mu..m diameter, which appears to be soluble in tetrahydrofuran. The yields of solute were significantly much higher than for raw coals. Molecular weight of the solute material was high, being in the range of 600 to 3000. The above and substantiating evidence point to a new mechanism of high heating rate pyrolysis in which only tar-like materials are produced as primary products from the coal. It is hypothesized that gas phase products are primarily the result of secondary reactions of these primary products in the hot gas environments usually employed by other heating techniques.

Synchrotron X-ray scattering characterization of the molecular structures of star polystyrenes with varying numbers of arms.

Science.gov (United States)

Jin, Sangwoo; Higashihara, Tomoya; Jin, Kyeong Sik; Yoon, Jinhwan; Rho, Yecheol; Ahn, Byungcheol; Kim, Jehan; Hirao, Akira; Ree, Moonhor

2010-05-20

We have synthesized well-defined multiarmed star polystyrenes, with 6, 9, 17, 33, and 57 arms, and studied their molecular shapes and structural characteristics in a good solvent (tetrahydrofuran at 25 degrees C) and in a theta (Theta) solvent (cyclohexane at 35 degrees C) by small-angle X-ray scattering (SAXS) using a synchrotron radiation source. Analysis of the SAXS data provided a detailed characterization of the molecular shapes, including the contributions of the blob morphology of the arms, the radius of gyration, the paired distance distribution, the radial electron density distribution, and the Zimm-Stockmayer and Roovers g-factor, for the multiarmed star polystyrenes. In particular, the molecular shapes of the star polystyrenes were found to change from a fuzzy ellipsoid, for the 6-armed polystyrene, to a fuzzy sphere, for the 57-armed polystyrene, with an increasing number of arms. The ellipsoidal character of the star polystyrenes with fewer arms may originate from the extended anisotropically branched architecture at the center of the molecule. The arms of the star polystyrenes were found to be more extended than those of the linear polystyrenes. Furthermore, the degree of chain extension in the arms increased with the number of arms.

Crosslinked polytriazole membranes for organophilic filtration

KAUST Repository

Chisca, Stefan

2016-12-30

We report the preparation of crosslinked membranes for organophilic filtration, by reacting a new polytriazole with free OH groups, using non-toxic poly (ethylene glycol) diglycidyl ether (PEGDE). The OH-functionalized polymer was obtained by converting the oxadiazole to triazole rings with high yield (98%). The maximum degree of crosslinking is achieved after 6 h of reaction. The crosslinked polytriazole membranes are stable in a wide range of organic solvents and show high creep recovery, indicating the robustness of crosslinked membranes. The influence of different casting solutions and different crosslinking time on the membrane morphology and membrane performance was investigated. The membranes performance was studied in dimethylformamide (DMF) and (tetrahydrofuran) THF. We achieved a permeance for THF of 49 L m−2 h−1 bar−1 for membranes with molecular weight cut off (MWCO) of 7 kg mol−1 and a permeance for THF of 17.5 L m−2 h−1 bar−1 for membranes with MWCO of 3 kg mol−1. Our data indicate that by using the new polytriazole is possible to adjust the pore dimensions of the membranes to have a MWCO, which covers ultra- and nanofiltration range.

The use of in situ Fourier-transform infrared spectroscopy for the study of surface phenomena on electrodes in selected lithium battery electrolyte solutions

Science.gov (United States)

Aurbach, D.; Chusid, O.

This paper presents some examples of surface studies of noble metals and Li electrodes in Li battery electrolyte solutions using in situ FT-IR spectroscopic techniques. These examples include the study of a mixture of solvents, the role of the reduction of salt in the build-up of surface films on the electrodes and the impact of contaminants such as traces of oxgen and water. The techniques included multiple and single internal reflectance modes and external reflectance (SNIFTIRS-type) mode. The following conclusions were drawn from this study: (i) salts containing the -SO 2CF 3 group are much more reactive on Li than LiAsF 6. Their reduction dominates the surface chemistry developed on Li in ethereal solutions; (ii) water reduction on Li in wet 1,3-dioxolane solution may not form stable LiOH films due to the further reaction of the hydroxy group with the solvent; (iii) in spite of its low solubility, oxygen dissolved in propylene carbonate and tetrahydrofuran solutions has some impact on the surface chemistry developed on Li in these solutions (probably due to Li 2O formation).

Deuteration of benzen derivatives and condensed aromatics

International Nuclear Information System (INIS)

Ichikawa, Masaru.

1970-01-01

A process for the deuteration of aromatic compounds (benzene derivatives having one or more cyano, halogeno, nitro or other electron attractive groups, and condensed ring aromatics) is provided. The process comprises reducing said aromatic compound with an alkali metal (preferably K, Rb or Cs) in a solvent (dimethoxyethane, tetrahydrofuran, etc.) to provide an electron-acceptor-donor complex, which is followed by introducing gaseous deuterium into the solution. The deuteration takes place selectively at the position of highest electron density in accordance with nature of the substituent, regardless of steric hindrance. The process is applicable to a wide variety of aromatics to give deuterated compounds in high yields. In one example, 5x10 -3 mole of anthracene (An) was reacted with 2g of metallic potassium in 80cc of dimethoxyethane in a N 2 atmosphere. Into the resulting solution of An=2K + was introduced D 2 gas (30 cmHg) at 25 0 C. After decomposition with air and washing with alcohol, the precipitate was recrystallized from benzene. Yield of recovered AN: more than 90%. Yield of deuteration: 100%. Position of deuteration: 9 and 10 (revealed by NMR and mass spectroscopy). (Kaichi, S.)

The synthesis and properties of linear A-π-D-π-A type organic small molecule containing diketopyrrolopyrrole terminal units

Science.gov (United States)

Zhang, Shanshan; Niu, Qingfen; Sun, Tao; Li, Yang; Li, Tianduo; Liu, Haixia

2017-08-01

A novel linear A-π-D-π-A-type organic small molecule Ph2(PDPP)2 consisting diketopyrrolopyrrole (DPP) as acceptor unit, biphenylene as donor unit and acetylene unit as π-linkage has been successfully designed and synthesized. Its corresponding thermal, photophysical and electrochemical properties as well as the photoinduced charge-separation process were investigated. Ph2(PDPP)2 exhibits high thermal stability and it can be soluble in common organic solvents such as chloroform and tetrahydrofuran. The photophysical properties show that DPP2Ph2 harvests sunlight over the entire visible spectrum range in the thin-film state (300-800 nm). DPP2Ph2 has lower band gaps and appropriate energy levels to satisfy the requirement of solution-processable organic solar cells. The efficient photoinduced charge separation process was clearly observed between DPP2Ph2 with PC61BM and the Ksv value was found to be as high as 2.13 × 104 M- 1. Therefore, these excellent properties demonstrate that the designed A-π-D-π-A-type small molecule Ph2(PDPP)2 is the prospective candidate as donor material for organic photovoltaic material.

Stability and Unimolecular Reactivity of Palladate(II) Complexes [Ln PdR3 ]- (L=Phosphine, R=Organyl, n=0 and 1).

Science.gov (United States)

Kolter, Marlene; Koszinowski, Konrad

2016-10-24

The reduction of Pd II precatalysts to catalytically active Pd 0 species is a key step in many palladium-mediated cross-coupling reactions. Besides phosphines, the stoichiometrically used organometallic reagents can afford this reduction, but do so in a poorly understood way. To elucidate the mechanism of this reaction, we have treated solutions of Pd(OAc) 2 and a phosphine ligand L in tetrahydrofuran with RMgCl (R=Ph, Bn, Bu) as well as other organometallic reagents. Analysis of these model systems by electrospray- ionization mass spectrometry found palladate(II) complexes [L n PdR 3 ] - (n=0 and 1), thus pointing to the occurrence of transmetallation reactions. Upon gas-phase fragmentation, the [L n PdR 3 ] - anions preferentially underwent a reductive elimination to yield Pd 0 species. The sequence of the transmetallation and reductive elimination, thus, constitutes a feasible mechanism for the reduction of the Pd(OAc) 2 precatalyst. Other species of interest observed include the Pd IV complex [PdBn 5 ] - , which did not fragment via a reductive elimination but lost BnH instead. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Understanding and controlling the rest potential of carbon nanotube-based supercapacitors for energy density enhancement

Science.gov (United States)

Yoo, Young-Eun; Park, Jinwoo; Kim, Woong

2018-03-01

We present a novel method for enhancing the energy density of an electrical double layer capacitor (EDLC). Surface modification of single-walled carbon nanotube (SWNT) electrodes significantly affects the rest potential (E0) of EDLCs; acid treatment and polyethyleneimine (PEI) coating of SWNTs shift E0 toward more positive and more negative values, respectively. Adjusting E0 towards the center of the electrolyte stability window can increase the cell voltage and hence the energy density. PEI coating on SWNTs increases the cell voltage from 0.8 V to 1.7 V in tetrabutylammonium perchlorate (TBAP)/tetrahydrofuran (THF) electrolyte, and from 2.5 V to 3.1 V in tetraethylammonium tetrafluoroborate (TEABF4)/3-cyanopropionic acid methyl ester (CPAME), respectively. Moreover, PEI-SWNT EDLCs exhibit excellent cycling stability (92% of capacitance retention over 10000 cycles). We attribute the shift in E0 to a change in the Fermi level of SWNTs owing to the surface charge modification. Injection of electrical charge into PEI-SWNTs consistently yielded similar trends and thus validated our hypothesis. Our results may help to push various electrolytes that have been overlooked so far to new frontiers for obtaining high energy-density supercapacitors.

Stability optimisation of molecular electronic devices based on  nanoelectrode–nanoparticle bridge platform in air and different storage liquids

International Nuclear Information System (INIS)

Jafri, S. H. M.; Blom, T.; Wallner, A.; Ottosson, H.; Leifer, K.

2014-01-01

The long-term stability of metal nanoparticle–molecule junctions in molecular electronic devices based on nanoelectrodes (NEL) is a major challenge in the effort to bring related molecular electronic devices to application. To optimize the reproducibility of molecular electronic nanodevices, the time-dependent modification of such junctions as exposed to different media needs to be known. Here, we have studied (1) the stability of Au-NEL and (2) the electrical stability of molecule–Au nanoparticle (AuNP) junctions themselves with the molecule being  1,8-octanedithiol (ODT). Both the NELs only and the junctions were exposed to air and liquids such as deionized water, tetrahydrofuran, toluene and tetramethylethylenediamine (TMEDA) over a period of 1 month. The nanogaps remained stable in width when stored in either deionized water or toluene, whereas the current through 1,8-octanedithiol–NP junctions remained most stable when stored in TMEDA as compared to other solvents. Although it is difficult to follow the chemical processes in such devices in the 10-nm range with analytical methods, the behavior can be interpreted from known interactions of solvent molecules with electrodes and ODT

Thermodynamic properties of hyperbranched polymer, Boltorn U3000, using inverse gas chromatography.

Science.gov (United States)

Domańska, Urszula; Zołek-Tryznowska, Zuzanna

2009-11-19

Mass-fraction activity coefficients at infinite dilution (Omega13(infinity)) of alkanes (C5-C10), cycloalkanes (C5-C8), alkenes (C5-C8), alkynes (C5-C8), aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-, m-, p-xylene, thiophene), alcohols (C1-C5), water, ethers (tetrahydrofuran (THF), methyl-tert-butylether (MTBE), diethyl-, di-n-propyl-, di-n-butyl ether), and ketones (propanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, cyclopentanone) in the hyperbranched polymer, Boltorn U3000 (B-U3000), have been determined by inverse gas chromatography (IGC) using the polymer as the stationary phase. The measurements were carried out at different temperatures between 308.15 and 348.15 K. The density and thermophysical properties of polymer were described. The specific retention volume (V(g)), the Flory-Huggins interaction parameter (chi13(infinity)), the molar enthalpy of sorption (the partial molar enthalpies of solute dissolution) (Delta(s)H), the partial molar excess enthalpy at infinite dilution of the solute and polymer (DeltaH1(E,infinity)), the partial molar Gibbs excess energy at infinite dilution (DeltaG1(E,infinity)), and the solubility parameter (delta3) were calculated.

Preparation of Carbon-Chitosan-Polyvinyl Chloride (CC-PVC) Material and its Application to Electrochemical Degradation of Methylene Blue in Sodium Chloride Solution

Science.gov (United States)

Riyanto; Prawidha, A. D.

2018-01-01

Electrochemical degradation of methylene blue using Carbon-Chitosan-Polyvinyl Chloride (CC-PVC) electrode in sodium chloride have been done. The aim of this work was to degradation of methylene blue using Carbon-Chitosan-Polyvinyl Chloride (CC-PVC). Carbon chitosan composite electrode was preparing by Carbon and Chitosan powder and PVC in 4 mL tetrahydrofuran (THF) solvent and swirled flatly to homogeneous followed by drying in an oven at 100 °C for 3 h. The mixture was placed in stainless steel mould and pressed at 10 ton/cm2. Sodium chloride was used electrolyte solution. The effects of the current and electrolysis time were investigated using spectrophotometer UV-Visible. The experimental results showed that the carbon-chitosan composite electrode have higher effect in the electrochemical degradation of methylene blue in sodium chloride. Based on UV-visible spectra analysis shows current and electrolysis time has high effect to degradation of methylene blue in sodium chloride. Chitosan and polyvinyl chloride can strengthen the bond between the carbons so that the material has the high stability and conductivity. As conclusions is Carbon-Chitosan-Polyvinyl Chloride (CC-PVC) electrode have a high electrochemical activity for degradation of methylene blue in sodium chloride.

Study of equivalent retention among different polymer-solvent systems in thermal field-flow fractionation

International Nuclear Information System (INIS)

Kim, Won Suk; Park, Young Hun; Lee, Dai Woon; Moon, Myeong Hee; Yu, Euy Kyung

1998-01-01

An equivalent retention has been experimentally observed in thermal field-flow fractionation (ThFF) for different polymer-solvent systems. It is shown that iso-retention between two sets of polymer-solvent systems can be obtained by adjusting the temperature difference (ΔT) according to the difference in the ration of ordinary diffusion coefficient to thermal diffusion coefficient. This method uses a compensation of field strength (ΔT) in ThFFF at a fixed condition of cold wall temperature. It is applied for the calculation of molecular weight of polymers based on a calibration run of different standards obtained at an adjusted ΔT. The polymer standards used in this study are polystyrene (PS), polymethylmethacrylate (PMMA), and polytetrahydrofuran (PTHF). Three carrier solvents, tetrahydrofuran (THF), methylethylketone (MEK) and ethylacetate (ETAc) were employed. Though the accuracy in the calculation of molecular weight is dependent on the difference in the slope of log λ vs. log M which is related to Mark-Houwink constant a, it shows reasonable agreement within about 6% of relative error in molecular weight calculation for the polymer-solvent systems having similar a value

Spectral and thermodynamic properties for the exciplexes of N-alkyl carbazoles with dicyanobenzenes in THF

Science.gov (United States)

Asim, Sadia; Mansha, Asim; Landgraf, Stephan; Grampp, Günter; Zahid, Muhammad; Bhatti, Haq Nawaz

2014-01-01

The exciplex emission spectra of N-ethylcarbazole with 1,2-dicyanobenzene (NEC/1,2-DCB), N-methylcarbazole with 1,2-dicyanobenzene (NMC/1,2-DCB), 1,3-dicyanobenzene (NMC/1,3-DCB), and 1,4-dicyanobenzene (NMC/1,4-DCB) are studied in tetrahydrofuran (THF) for the temperature range starting from 253 K to 334 K. Thermochromic shifts along with the spectral properties including change in peak intensities and the ratio of exciplex peak intensity to fluorophore peak intensity are studied. Effect of temperature on the energy of zero-zero transitions hνo‧, Huang-Rhys factor (S), Gauss broadening of vibronic level (σ) and the dominant high-frequency vibration (hνν) are also part of investigation. Enthalpy of exciplex formation (ΔHEX∗) calculated by the model proposed by A. Weller and the Gibb's energy of electron transfer (ΔGet∗) for all exciplex systems are also discussed in the present paper. All the exciplexes under study were observed to be dipolar in nature. The exciplex of the N-methylcarbazole/1,4-dicyanobenzene was found to be the most stable and the N-methylcarbazole/1,3-dicyanobenzene was the weakest exciplex system.

Exciplex formation of copper(II) octaethylporphyrin revealed by pulsed x-rays

International Nuclear Information System (INIS)

Chen, L.X.; Shaw, G.B.; Liu, T.; Jennings, G.; Attenkofer, K.

2004-01-01

The triplet excited structures of Cu(II) octaethylporphyrin (CuOEP) in toluene and in 1:1 mixture of toluene and tetrahydrofuran (THF) were investigated by time-domain laser pulse pump, X-ray pulse probe X-ray absorption spectroscopy (pump-probe XAS) at room temperature using X-rays from a third generation synchrotron source with 100-ps time resolution. The transient optical absorption measurements indicate a strong solvent dependency of the triplet excited state lifetime due to the presence of oxygen-containing solvent molecules. While the ground state CuOEP molecules remain square-planar in both solvents, the attenuation of a peak attributed to the 1s → 4p z transition at the Cu K-edge for the laser excited CuOEP in the THF/toluene mixture revealed the penta-coordinated exciplex formation which is responsible for the shortening of the triplet excited state lifetime. Meanwhile, the average Cu-N distance in the triplet excited state is lengthened by 0.03 (angstrom) due to ligation with a THF solvent molecule, which agrees with a domed coordination structure for copper in the penta-coordinated exciplex.

Exciplex formation in bimolecular photoinduced electron-transfer investigated by ultrafast time-resolved infrared spectroscopy.

Science.gov (United States)

Koch, Marius; Letrun, Romain; Vauthey, Eric

2014-03-12

The dynamics of bimolecular photoinduced electron-transfer reactions has been investigated with three donor/acceptor (D/A) pairs in tetrahydrofuran (THF) and acetonitrile (ACN) using a combination of ultrafast spectroscopic techniques, including time-resolved infrared absorption. For the D/A pairs with the highest driving force of electron transfer, all transient spectroscopic features can be unambiguously assigned to the excited reactant and the ionic products. For the pair with the lowest driving force, three additional transient infrared bands, more intense in THF than in ACN, with a time dependence that differs from those of the other bands are observed. From their frequency and solvent dependence, these bands can be assigned to an exciplex. Moreover, polarization-resolved measurements point to a relatively well-defined mutual orientation of the constituents and to a slower reorientational time compared to those of the individual reactants. Thanks to the minimal overlap of the infrared signature of all transient species in THF, a detailed reaction scheme including the relevant kinetic and thermodynamic parameters could be deduced for this pair. This analysis reveals that the formation and recombination of the ion pair occur almost exclusively via the exciplex.

Microstructure of natural hydrate host sediments

International Nuclear Information System (INIS)

Jones, K.W.; Kerkar, P.B.; Mahajan, D.; Lindquist, W.B.; Feng, H.

2007-01-01

There is worldwide interest in the study of natural gas hydrate because of its potential impact on world energy resources, control on seafloor stability, significance as a drilling hazard and probable impact on climate as a reservoir of a major greenhouse gas. Gas hydrates can (a) be free floating in the sediment matrix (b) contact, but do not cement, existing sediment grains, or (c) actually cement and stiffen the bulk sediment. Seismic surveys, often used to prospect for hydrates over a large area, can provide knowledge of the location of large hydrate concentrations because the hydrates within the sediment pores modify seismic properties. The ability to image a sample at the grain scale and to determine the porosity, permeability and seismic profile is of great interest since these parameters can help in determining the location of hydrates with certainty. We report here on an investigation of the structure of methane hydrate sediments at the grain-size scale using the synchrotron radiation-based computed microtomography (CMT) technique. Work has started on the measurements of the changes occurring as tetrahydrofuran hydrate, a surrogate for methane hydrate, is formed in the sediment

Using Photosensitive Dye To Improve Multi Walled Carbon Nanotubes Dispersion

Energy Technology Data Exchange (ETDEWEB)

Diaz Costanzo, Guadalupe; Goyanes, Silvia [Laboratorio de PolImeros y Materiales Compuestos, Dpto. de Fisica, FCEyN, Universidad de Buenos Aires (Argentina) (Argentina); Ledesma, Silvia, E-mail: ledesma@df.uba.ar [Laboratorio de Procesado de Imagenes, Dpto. de Fisica, FCEyN, Universidad de Buenos Aires (Argentina) (Argentina)

2011-01-01

As already well-known, the outstanding mechanical and electrical properties of carbon nanotubes (CNT) are partially lost when CNT aggregate. The fact that CNT tend to aggregate makes difficult to put them into a host matrix, for example. Until now, achieving stable dispersions of CNT is still a challenge. In the present work, we show that the addition of an azobenzene derivative, Disperse Orange 3 (DO3) to dispersions of multi walled carbon nanotubes (MWCNT) in the organic solvent tetrahydrofuran (THF) efficiently helps debundling MWCNT and makes dispersions stable for days. We report UV-Vis optical absorption experiments that suggest an interaction between MWCNT and DO3 molecules following the behavior qualitatively observed. Dispersions with MWCNT and DO3 in THF were observed qualitatively over time. Successful suspensions (for the higher DO3 concentrations studied) were stable for several days. Also, we prepared polymeric films doped with MWCNT non-covalent functionalized with DO3 in one of the proper DO3/MWCNT weight relation where stable supensions were obtained. In this study we show preliminary results where the optical response of these samples was also measured.

Polar aprotic solvent-water mixture as the medium for catalytic production of hydroxymethylfurfural (HMF) from bread waste.

Science.gov (United States)

Yu, Iris K M; Tsang, Daniel C W; Chen, Season S; Wang, Lei; Hunt, Andrew J; Sherwood, James; De Oliveira Vigier, Karine; Jérôme, François; Ok, Yong Sik; Poon, Chi Sun

2017-12-01

Valorisation of bread waste for hydroxymethylfurfural (HMF) synthesis was examined in dimethyl sulfoxide (DMSO)-, tetrahydrofuran (THF)-, acetonitrile (ACN)-, and acetone-water (1:1v/v), under heating at 140°C with SnCl 4 as the catalyst. The overall rate of the process was the fastest in ACN/H 2 O and acetone/H 2 O, followed by DMSO/H 2 O and THF/H 2 O due to the rate-limiting glucose isomerisation. However, the formation of levulinic acid (via rehydration) and humins (via polymerisation) was more significant in ACN/H 2 O and acetone/H 2 O. The constant HMF maxima (26-27mol%) in ACN/H 2 O, acetone/H 2 O, and DMSO/H 2 O indicated that the rates of desirable reactions (starch hydrolysis, glucose isomerisation, and fructose dehydration) relative to undesirable pathways (HMF rehydration and polymerisation) were comparable among these mediums. They also demonstrated higher selectivity towards HMF production over the side reactions than THF/H 2 O. This study differentiated the effects of polar aprotic solvent-water mediums on simultaneous pathways during biomass conversion. Copyright © 2017 Elsevier Ltd. All rights reserved.

Crosslinked polytriazole membranes for organophilic filtration

KAUST Repository

Chisca, Stefan; Falca, Gheorghe; Musteata, Valentina-Elena; Boi, Cristiana; Nunes, Suzana Pereira

2016-01-01

We report the preparation of crosslinked membranes for organophilic filtration, by reacting a new polytriazole with free OH groups, using non-toxic poly (ethylene glycol) diglycidyl ether (PEGDE). The OH-functionalized polymer was obtained by converting the oxadiazole to triazole rings with high yield (98%). The maximum degree of crosslinking is achieved after 6 h of reaction. The crosslinked polytriazole membranes are stable in a wide range of organic solvents and show high creep recovery, indicating the robustness of crosslinked membranes. The influence of different casting solutions and different crosslinking time on the membrane morphology and membrane performance was investigated. The membranes performance was studied in dimethylformamide (DMF) and (tetrahydrofuran) THF. We achieved a permeance for THF of 49 L m−2 h−1 bar−1 for membranes with molecular weight cut off (MWCO) of 7 kg mol−1 and a permeance for THF of 17.5 L m−2 h−1 bar−1 for membranes with MWCO of 3 kg mol−1. Our data indicate that by using the new polytriazole is possible to adjust the pore dimensions of the membranes to have a MWCO, which covers ultra- and nanofiltration range.

Exploration of spectroscopic properties of solvated tris(thenoyltrifluoroacetonate)(2,2′-bipyridine)europium(III)red hybrid organic complex for solution processed OLEDs and displays

International Nuclear Information System (INIS)

Chitnis, Dipti; Thejokalyani, N.; Dhoble, S.J.

2017-01-01

In order to explore the spectroscopic properties of a novel europium activated hybrid organic tris(thenoyltrifluoroacetonate)(2,2′-bipyridine)europium(III), Eu(TTA) 3 bipy phosphor in various solvents at different pH and molar concentrations, UV–vis optical absorption and photoluminescence spectra were carried out. With a variation in the solvent from basic (chloroform, toluene, tetrahydrofuran) to acidic (acetic acid, formic acid) media, staggering differences in optical absorptions and optical densities were noticed with hypsochromic shift in the absorption peaks. The optical density was found to be maximum for the complex with pH= 7.0 and the intensity as well as optical density gradually decreased when pH is lowered to 6.0 or raised to 8.0 (at an interval of 0.5), proving that the complex is pH sensitive. It's optical energy gap and stokes shift values in various organic solvents were also calculated on the basis of Lippert-Mataga plot. The exploration of spectroscopic properties of solvated Eu(TTA) 3 bipy complex demonstrates its prospective for solution processed OLEDs and display devices. - Graphical abstract: Pictorial depiction of photoluminescence in solvated Eu(TTA) 3 bipy complex under UV light.

Lithium alkyl anions of uranium(IV) and uranium(V)

International Nuclear Information System (INIS)

Sigurdson, E.R.; Wilkinson, G.

1977-01-01

Organouranium compounds with six or eight uranium-to-carbon sigma-bonds have been synthesized for the first time. The interaction of uranium tetrachloride with lithium alkyls in diethyl ether leads to the isolation of unstable lithium alkyluranate(IV) compounds of stoicheiometry Li 2 UR 6 .8Et 2 0 (R = Me, CH 2 SiMe 3 . Ph, and o-Me 2 NCH 2 C 6 H 4 ). These lithium salts can also be obtained with other donor solvents, such as tetrahydrofuran or NNN'N'-tetramethylethylenediamine. From uranium pentaethoxide similar lithium salts of stoicheiometry Li 3 UR 8 .3 dioxan (R = Me, CH 2 CMe 3 , and CH 2 SiMe 3 ) can be obtained. The interaction of uranium(VI) hexaisopropoxide with lithium, magnesium, or aluminium alkyls does not give compounds containing U-C bonds, but green oils, e.g. U(OPrsup(i)) 6 (MgMe 2 ) 3 , that appear to be adducts in which the oxygen atom of the isopropoxide group bound to uranium is acting as a donor. I.r. and n.m.r. spectroscopy and analytical data for the new compounds are presented. (author)

Radiation-induced copolymerization of methyl trifluoroacrylate with α-olefins

International Nuclear Information System (INIS)

Matsuda, O.; Watanabe, T.; Tabata, Y.; Machi, S.

1978-01-01

Paper describes the radiation-induced bulk copolymerization of methyl trifluoroacrylate with various α olefins; propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and isobutylene. MTFA (purity above 98%) was synthesized by method described in literature. Reagent grade α-olefins were used. An equimolar mixture of MTFA and α-olefin was charged into the reactor. Trace amounts of oxygen were purged by the freeze-thaw technique. Irradiation was carried out with gamma rays from a 60 Co source under vapor pressure of the monomers at 25 0 C. The product was precipitated and washed with methanol to remove unreacted monomers, and dried under vacuum at 60 0 C. Infrared spectra of the copolymers were measured; compositions were determined from elemental analysis. Reactivity of the α-olefins appears to be related to the electron density at the double bond. All copolymers were found to have almost equimolar compositions and were soluble in polar solvents such as tetrahydrofuran and acetone. Copolymerization was inhibited completely by the addition of 1,1-diphenyl-2-picrihydrazil, but not by water, indicating that the copolymerization proceeds via a radical mechanism. 1 table; 2 figures

Micro-Tomographic Investigation of Ice and Clathrate Formation and Decomposition under Thermodynamic Monitoring

Directory of Open Access Journals (Sweden)

Stefan Arzbacher

2016-08-01

Full Text Available Clathrate hydrates are inclusion compounds in which guest molecules are trapped in a host lattice formed by water molecules. They are considered an interesting option for future energy supply and storage technologies. In the current paper, time lapse 3D micro computed tomographic (µCT imaging with ice and tetrahydrofuran (THF clathrate hydrate particles is carried out in conjunction with an accurate temperature control and pressure monitoring. µCT imaging reveals similar behavior of the ice and the THF clathrate hydrate at low temperatures while at higher temperatures (3 K below the melting point, significant differences can be observed. Strong indications for micropores are found in the ice as well as the THF clathrate hydrate. They are stable in the ice while unstable in the clathrate hydrate at temperatures slightly below the melting point. Significant transformations in surface and bulk structure can be observed within the full temperature range investigated in both the ice and the THF clathrate hydrate. Additionally, our results point towards an uptake of molecular nitrogen in the THF clathrate hydrate at ambient pressures and temperatures from 230 K to 271 K.

Production of Biodiesel from Waste Vegetable Oil via KM Micromixer

Directory of Open Access Journals (Sweden)

M. F. Elkady

2015-01-01

Full Text Available The production of biodiesel from waste vegetable oils through its pretreatment followed by transesterification process in presence of methanol was investigated using a KM micromixer reactor. The parameters affecting biodiesel production process such as alcohol to oil molar ratio, catalyst concentration, the presence of tetrahydrofuran (THF as a cosolvent, and the volumetric flow rates of inlet fluids were optimized. The properties of the produced biodiesel were compared with its parent waste oil through different characterization techniques. The presence of methyl ester groups at the produced biodiesel was confirmed using both the gas chromatography-mass spectrometry (GC-MS and the infrared spectroscopy (FT-IR. Moreover, the thermal analysis of the produced biodiesel and the comparable waste oil indicated that the product after the transesterification process began to vaporize at 120°C which makes it lighter than its parent oil which started to vaporize at around 300°C. The maximum biodiesel production yield of 97% was recorded using 12 : 1 methanol to oil molar ratio in presence of both 1% NaOH and THF/methanol volume ratio 0.3 at 60 mL/h flow rate.

CCDC 873769: Experimental Crystal Structure Determination : (1,3-bis(2,6-Di-isopropylphenyl)imidazol-2-ylidene)-(formato-O)-hydrido-(tricyclohexylphosphine)-palladium tetrahydrofuran solvate

KAUST Repository

Broggi, Julie; Jurčí k, Vá clav; Songis, Olivier; Poater, Albert; Cavallo, Luigi; Slawin, Alexandra M. Z.; Cazin, Catherine S. J.

2014-01-01

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

2,3,4,6-Tetra-O-acetyl-β-d-galactopyranosyl 2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl disulfide tetrahydrofuran solvate

Directory of Open Access Journals (Sweden)

Matías López-Rodríguez

2008-12-01

Full Text Available The asymmetric unit of title compound, C28H38O18S2·C4H8O, comprises one disulfide-bridged sugar molecule and one solvent molecule. No significant differences in structural parameters are found between the present structure and the previously determined unsolvated form [Brito, López-Rodríguez, Bényei & Szilagyi (2006. Carbohydr. Res. 341, 2967–2972]. The compounds are characterized by a compact structure with spatial proximity of the two pyranosyl rings. One of the carbonyl atoms is disordered over two sites [site occupancy = 0.69 (7 for major component] and the displacement parameters for the THF species are unsually large.