Sample records for acetonitrile

  1. Acetonitrile in the air over Europe

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    Hamm, S.; Helas, G.; Warneck, P.


    A gas chromatographic technique was developed to measure acetonitrile mixing ratios in air samples collected during three aircraft flights over Europe. Uniform mixing ratios were observed in the troposphere independent of altitude, with an average of 144+-26 pptv for the first two flights, and 194+-7 pptv for the third. /copyright/ American Geophysical Union 1989

  2. Acetonitrile in the air over Europe (United States)

    Hamm, S.; Helas, G.; Warneck, P.


    A gas chromatographic technique was developed to measure acetonitrile mixing ratios in air samples collected during three aircraft flights over Europe. Uniform mixing ratios were observed in the troposphere, independent of altitude, with an average of 144 + or - 26 pptv for the first two flights and 194 + or - 7 pptv for the third.

  3. Iodidotris(triphenylphosphinecopper(I acetonitrile solvate

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    Frank R. Fronczek


    Full Text Available The title compound, [CuI(C18H15P3]·C2H3N, was obtained from the reaction of triphenylphosphine and copper(I iodide in acetonitrile. The monomeric form of the complex has slightly distorted coordination of Cu by the I atom and three P atoms. The crystal structure is stabilized by C—H...π interactions between phenyl H atoms and phenyl rings. In addition, the complex molecules exhibit C—H...N hydrogen bonds between phenyl H atoms and acetonitrile N atoms. The crystal used was an inversion twin, with nearly equal component populations of 0.522 (8 and 0.478 (8.

  4. Tris(acetonitrile-κNdichlorido(triphenylphosphane-κPruthenium(II acetonitrile monosolvate

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    Xiao-Feng Yin


    Full Text Available In the title complex, [RuCl2(CH3CN3(C18H15P]·CH3CN, the coordination geometry of the RuII atom is distorted octahedral, defined by one P atom from a triphenylphosphane ligand, three N atoms from three acetonitrile ligands and two Cl atoms. The three acetronitile ligands linearly bind to the RuII atom, with Ru—N—C angles of 172.6 (2, 179.9 (2 and 171.4 (2°.

  5. Hexakis(acetonitrile-κNruthenium(II bis(hexabromocarbadodecaborate acetonitrile solvate

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    Anna Larsen


    Full Text Available The title compound, [Ru(NCCH36](CH6B11Br62·CH3CN, consists of the 'naked' ruthenium(II cation surrounded by six acetonitrile molecules, each coordinated via the nitrogen atoms in a linear or nearly-linear fashion in a typical octahedral over-all arrangement. The cation is balanced by the two hexa-bromocarborane cage anionic fragments [CB11H6Br6]. Weak C—H...Br and B—H...Br interactions link neighboring anions.

  6. Intermolecular forces in acetonitrile + ethanol binary liquid mixtures (United States)

    Elangovan, A.; Shanmugam, R.; Arivazhagan, G.; Mahendraprabu, A.; Karthick, N. K.


    FTIR spectral measurements have been carried out on the binary mixtures of acetonitrile with ethanol at 1:0 (acetonitrile:ethanol), 1:1, 1:2, 1:3 and 0:1 at room temperature. DFT and isosurface calculations have been performed. The acetonitrile + ethanol binary mixtures consist of 1:1, 1:2, 1:3 and 1:4 complexes formed through both the red and blue shifting H-bonds. Inter as well as intra molecular forces are found to exist in 1:3 and 1:4 complexes.

  7. Acetonitrile Ion Suppression in Atmospheric Pressure Ionization Mass Spectrometry (United States)

    Colizza, Kevin; Mahoney, Keira E.; Yevdokimov, Alexander V.; Smith, James L.; Oxley, Jimmie C.


    Efforts to analyze trace levels of cyclic peroxides by liquid chromatography/mass spectrometry gave evidence that acetonitrile suppressed ion formation. Further investigations extended this discovery to ketones, linear peroxides, esters, and possibly many other types of compounds, including triazole and menadione. Direct ionization suppression caused by acetonitrile was observed for multiple adduct types in both electrospray ionization and atmospheric pressure chemical ionization. The addition of only 2% acetonitrile significantly decreased the sensitivity of analyte response. Efforts to identify the mechanism were made using various nitriles. The ion suppression was reduced by substitution of an acetonitrile hydrogen with an electron-withdrawing group, but was exacerbated by electron-donating or steric groups adjacent to the nitrile. Although current theory does not explain this phenomenon, we propose that polar interactions between the various functionalities and the nitrile may be forming neutral aggregates that manifest as ionization suppression.

  8. Inhalation developmental toxicology studies: Acetonitrile in rats. Final report

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    Mast, T.J.; Weigel, R.J.; Westerberg, R.B.; Boyd, P.J.; Hayden, B.K.; Evanoff, J.J.; Rommereim, R.L.


    The potential for acetonitrile to cause developmental toxicity was assessed in Sprague-Dawley rats exposed to 0, 100, 400, or 1200 ppM acetonitrile, 6 hours/day, 7 days/week. Exposure of rats to these concentrations of acetonitrile resulted in mortality in the 1200 ppM group (2/33 pregnant females; 1/10 non-pregnant females). However, there were no treatment-related effects upon body weights or reproduction indices at any exposure level, nor was there a significant increase in the incidence of fetal malformations or variations. The only effect observed in the fetuses was a slight, but not statiscally significant, exposure-correlated increase in the incidence of supernumerary ribs. Determination of acetonitrile and cyanide concentrations in maternal rat blood showed that acetonitrile concentration in the blood increased with exposure concentration for all exposed maternal rats. Detectable amounts of cyanide in the blood were found only in the rats exposed to 1200 ppM acetonitrile ({approximately}2 {mu}g cyanide/g of blood).

  9. Laser synthesis and spectroscopy of acetonitrile/silver nanoparticles (United States)

    Akin, S. T.; Liu, X.; Duncan, M. A.


    Silver nanoparticles with acetonitrile ligands are produced in a laser ablation flow reactor. Excimer laser ablation produces gas phase metal clusters which are thermalized with helium or argon collisions in the flowtube, and reactions with acetonitrile vapor coordinate this ligand to the particle surface. The gaseous mixture is captured in a cryogenic trap; warming produces a solution of excess ligand and coated particles. TEM images reveal particle sizes of 10-30 nm diameter. UV-vis absorption and fluorescence spectra are compared to those of standard silver nanoparticles with surfactant coatings. Deep-UV ligand absorption is strongly enhanced by nanoparticle adsorption.

  10. (Acetonitrile-κNiodidobis(triphenylphosphane-κPcopper(I

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    Yupa Wattanakanjana


    Full Text Available In the mononuclear title complex, [CuI(CH3CN(C18H15P2], the CuI ion is in a distorted tetrahedral geometry, coordinated by two P atoms of two triphenylphosphane ligands, one N atom of an acetonitrile ligand and one iodide anion. The acetonitrile ligand is disordered over two sets of sites in a 0.629 (15: 0.371 (15 ratio. In the crystal, weak C—H...I hydrogen bonds link the molecules, forming a chain along [100].

  11. Study of the cerium(IV)-picrate system in acetonitrile. (United States)

    Kratochvil, B; Tipler, M; McKay, B


    A potentiometric and spectrophotometric study has been made of the reaction between hexanitratocerate and picrate in dry acetonitrile. Several cerium(IV)-picrate complexes are formed; the formation constant for the first is estimated to be 4 from spectrophotometric measurements. The catalytic effect of picrate on hydroquinone oxidation by nitratocerate is postulated to be due to more rapid electron transfer by cerium picrate complexes.

  12. Detection of amino acetonitrile in Sgr B2(N)

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    Belloche, A; Comito, C; Müller, H S P; Schilke, P; Ott, J; Thorwirth, S; Hieret, C


    Amino acids are building blocks of proteins and therefore key ingredients for the origin of life. The simplest amino acid, glycine, has long been searched for in the interstellar medium but has not been unambiguously detected so far. Since the search for glycine has turned out to be extremely difficult, we aimed at detecting a chemically related species (possibly a direct precursor), amino acetonitrile. With the IRAM 30m telescope we carried out a complete line survey of the hot core regions Sgr B2(N) and (M) in the 3 mm range, plus partial surveys at 2 and 1.3 mm. We analyzed our 30m line survey in the LTE approximation and modeled the emission of all known molecules simultaneously. We identified spectral features at the frequencies predicted for amino acetonitrile lines having intensities compatible with a unique rotation temperature. We also used the VLA to look for cold, extended emission from amino acetonitrile. We detected amino acetonitrile in Sgr B2(N) in our 30m telescope line survey and conducted co...

  13. Determination of Acetonitrile Volume Fraction in Mobile Phase by HPLC

    Institute of Scientific and Technical Information of China (English)

    WU Yi; WANG Zhi-wu; GU Jing-kai; WANG Ying-wu


    This paper reports the development and validation of an assay for the determination of acetonitrile in the recycled mobile phase using high performance liquid chromatography(HPLC).The method is based on that the retention in reversed-phase liquid chromatography increases with decreasing concentration of organic phase in the mobile phase.The natural logarithm of the capacity ratio for a given solute is linearly related to the volume fraction of the organic modifier in the mobile phase.For dimethylphthalate and diethylphthalate,the linearity range is 30%--60%,and for biphenyl and terphenyl,the range is 60%-95%.Precision values(RSD) were both <1% and the accuracy(RE) was in the range of ±1%.The assay was successfully applied to the determination of acetonitrile concentration of recycled mobile phase after the distillation of the column eluent in our laboratory.

  14. Heat capacities of the mixtures of ionic liquids with acetonitrile

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    Waliszewski, Dariusz, E-mail: waliszew@uni.lodz.p [Department of Physical Chemistry, University of Lodz, Pomorska 165, PL-90 236 Lodz (Poland); Piekarski, Henryk [Department of Physical Chemistry, University of Lodz, Pomorska 165, PL-90 236 Lodz (Poland)


    Isobaric specific heat capacities were measured for left brace1-hexyl-3-methylimidazolium tetrafluoroborate (HMIMBF{sub 4}) + acetonitrile (MeCN)right brace and left brace1-methyl-3-octylimidazolium tetrafluoroborate (OMIMBF{sub 4}) + acetonitrileright brace within the whole range of composition and temperatures from (283.15 to 323.15) K. The excess molar heat capacities were calculated from the experimental results and satisfactorily fitted to Redlich-Kister type polynomials for several selected temperatures. Negative deviations from the additivity of molar heat capacities were observed within the whole composition range of (HMIBMF{sub 4} + MeCN) and (OMIMBF{sub 4} + MeCN). The results obtained have been interpreted in terms of interactions between ionic liquids and acetonitrile.

  15. (Acetonitrile[bis(2-pyridylmethylamine]bis(perchloratocopper(II

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    Ray J. Butcher


    Full Text Available In the title compound, [Cu(ClO42(C12H13N3(C2H3N], the CuII atom is six-coordinate in a Jahn–Teller distorted octahedral geometry, with coordination by the tridentate chelating ligand, an acetonitrile molecule, and two axial perchlorate anions. The tridentate ligand bis(2-pyridylmethylamine chelates meridionally and equatorially while an acetonitrile molecule is coordinated at the fourth equatorial site. The two perchlorate anions are disordered with site occupancy factors of 0.72/0.28. The amine H is involved in intramolecular hydrogen bonding to the perchlorate O atoms and there are extensive but weak intermolecular C—H...O interactions.

  16. Antioxidant and antibacterial activities of acetonitrile and hexane extracts of Lentinus tigrinus and Pleurotus djamour (United States)

    This paper highlighted the antioxidant and antibacterial activities of Lentinus tigrinus and Pleurotus djamour. Extracts of mushroom fruiting bodies were obtained using hexane and acetonitrile solvents. Acetonitrile extracts of both mushrooms exhibited higher biological activities than hexane extrac...

  17. Breath testing and personal exposure--SIFT-MS detection of breath acetonitrile for exposure monitoring. (United States)

    Storer, Malina; Curry, Kirsty; Squire, Marie; Kingham, Simon; Epton, Michael


    Breath testing has potential for the rapid assessment of the source and impact of exposure to air pollutants. During the development of a breath test for acetonitrile using selected ion flow tube mass spectrometry (SIFT-MS) raised acetonitrile concentrations in the breath of volunteers were observed that could not be explained by known sources of exposure. Workplace/laboratory exposure to acetonitrile was proposed since this was common to the volunteers with increased breath concentrations. SIFT-MS measurements of acetonitrile in breath and air were used to confirm that an academic chemistry laboratory was the source of exposure to acetonitrile, and quantify the changes that occurred to exhaled acetonitrile after exposure. High concentrations of acetonitrile were detected in the air of the chemistry laboratory. However, concentrations in the offices were not significantly different across the campus. There was a significant difference in the exhaled acetonitrile concentrations of people who worked in the chemistry laboratories (exposed) and those who did not (non-exposed). SIFT-MS testing of air and breath made it possible to determine that occupational exposure to acetonitrile in the chemistry laboratory was the cause of increased exhaled acetonitrile. Additionally, the sensitivity was adequate to measure the changes to exhaled amounts and found that breath concentrations increased quickly with short exposure and remained increased even after periods of non-exposure. There is potential to add acetonitrile to a suite of VOCs to investigate source and impact of poor air quality.

  18. Monocrotophos Molecularly Imprinted Microspheres Prepared by Precipitation Polymerization in Acetonitrile

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    Shoulei Yan; Zhixian Gao; Yanjun Fang; Yiyong Cheng


    Molecularly imprinted microspheres (MIP) for monocrotophos have been prepared by precipitation polymerization in acetonitrile (CAN) 60℃, 24 h, using methacrylic acid (MAA), ethylene glycol dimethacrylate (EGDMA) and 2,2-azobisiobutyronitrile (AIBN) as functional monomer, cross-linker and initiator, respectively. The recognition mechanism was elucidated by UV-vis spectra and computer modeling. Equilibrium binding experiment was employed to investigate the rebinding properties, Scatchard analysis showed that specific binding sites formed in the imprinted microspheres, and there were two kinds of binding sites, one was high binding sites, the other was low binding sites. This microspheres can be useful affinity absorbent used for organophosphorus pesticides separation and purification in food and environmental analysis.

  19. Photodegradation of Oryzalin in aqueous isopropanol and acetonitrile. (United States)

    Pramanik, Sukhendu Kumar; Joarder, Soumen; Das, Saktipada; Roy, Sankhajit; Bhattacharyya, Anjan


    The phototransformation of Oryzalin was studied under UV light (λmax ≥ 290 nm) and sunlight (λmax ≥ 250 nm) in aqueous isopropanol and acetonitrile solution in absence and presence of TiO2 as sensitizer. The rate of photodegradation of Oryzalin in different solvent system followed first-order kinetics, and calculated half-lives were found to be in the range of 23.52-53.75 h for UV light and 41.23-61.43 h for sunlight. From this study, total 12 photoproducts were identified and characterized on the basis of column chromatography and Q-Tof micromass spectral data. The plausible mechanism of phototransformation involved was hydrolysis, breaking of sulfonic bond, and loss of amino and sulfonic acid group.

  20. Determination of NO chemical affinities of benzyl nitrite in acetonitrile

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    Xin LI; Xiaoqing ZHU; Jinpei CHENG


    There is an increasing interest in the study of NO chemical affinities of organic nitrites, for the bio-logical and physiological effects of organic nitrites seem to be due to their ability to release NO. In this paper, NO chemical affinities of ten substituted benzyl nitrites were determined by titration calorimetry combined with a ther-modynamic cycle in acetonitrile solution. The results show that ΔHhet(O-NO)s of benzyl nitrites are substan-tially larger than the corresponding ΔHhomo(O-NO)s, suggesting that these O-nitroso compounds much more easily release NO radicals by the O-NO bond homolytic cleavage. It is believed that the structural and energetic information disclosed in this work should be useful in understanding chemical and biological functions of organic nitrites.

  1. Bis{2-[(Triphenylmethylamino]phenyl} diselenide acetonitrile monosolvate

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    Adam Neuba


    Full Text Available The molecular structure of the title compound, C50H40N2Se2·C2H3N, shows a syn conformation of the benzene rings bound to the Se atoms, with an Se—Se bond length of 2.3529 (6 Å and a C—Se—Se—C torsion angle of 93.53 (14°. The two Se-bonded aromatic ring planes make a dihedral angle of 18.42 (16°. Intramolecular N—H...Se hydrogen bonds are noted. Intermolecular C—H...Se interactions give rise to supramolecular chains extended along [100]. One severely disordered acetonitrile solvent molecule per asymmetric unit was treated with SQUEEZE in PLATON [Spek (2009. Acta Cryst. D65, 148–155]; the crystal data take the presence of this molecule into account.

  2. Excess molar volume of the acetonitrile + alcohol systems at 298.15 K. Part I: Density measurements for acetonitrile + methanol, + ethanol systems

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    Full Text Available The excess molar volume VE of the binary liquid systems acetonitrile + methanol and acetonitrile + ethanol has been evaluated from density measurements at 298.15 K and at atmospheric pressure over the entire composition range. A vibrating tube densimeter, type Anton Paar DMA 55, was applied for these measurements. The Redlich–Kister equation was used to fit the experimental VE data.

  3. Acetonitrile in the troposphere - Residence time due to rainout and uptake by the ocean (United States)

    Hamm, S.; Hahn, J.; Helas, G.; Warneck, P.


    Henry's law coefficients for the binary system acetonitrile-water are reported as a function of temperature from 279-303 K. The results are used to estimate the tropospheric residence time of acetonitrile due to wet precipitation (3 + or - 1.5 years) and the dry deposition velocity over the ocean (0.5 cm/s).

  4. Photocatalytic oxidation of acetonitrile in aqueous suspension of titanium dioxide irradiated by sunlight

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    Augugliaro, V.; Bianco Prevot, A.; Caceres Vazquez, J.; Garcia-Lopez, E.; Irico, A.; Loddo, V.; Malato Rodriguez, S.; Marci, G.; Palmisano, L.; Pramauro, E.


    The photocatalytic oxidation of acetonitrile (CH{sub 3}CN) was carried out in aqueous suspensions of polycrystalline UiO{sub 2} P25 Degussa irradiated by sunlight. A plus flow photoreactor in a total recycle loop was used for carrying out reactivity experiments in which the concentrations of acetonitrile, of its intermediate oxidation products and of not-purgeable organic carbon (NPOC) were monitored. The influence of the presence of strong oxidant species (H{sub 2}O{sub 2}, S{sub 2}O{sub 8}, CIO) on the process rate was studied. The dependence of acetonitrile photo-oxidation rate on the substrate concentration and on the catalyst amount was also investigated. The photodegradation rate of substrate and NPOC follows a first order kinetics with respect to acetonitrile and NPOC concentrations, respectively. The presence of S{sub {sup O}8}''2- and solar irradiation determines the occurrence of homogeneous degradation of acetonitrile and NPOC. In the presence of irradiated catalyst, a significant synergetic effect is observed for NPOC degradation while for the acetonitrile oxidation this effect is not evident. H{sub 2}O{sub 2} does not effect the process while CIO negatively affects the acetonitrile oxidation rate and it seems to inhibit the NPOC degradation. (Author) 20 refs.

  5. Laboratory investigations of irradiated acetonitrile-containing ices on an interstellar dust analog

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    Abdulgalil, Ali G. M.; Marchione, Demian; Rosu-Finsen, Alexander; Collings, Mark P.; McCoustra, Martin R. S. [School of Engineering and Physical Sciences, Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS (United Kingdom)


    Reflection-absorption infrared spectroscopy is used to study the impact of low-energy electron irradiation of acetonitrile-containing ices, under conditions close to those in the dense star-forming regions in the interstellar medium. Both the incident electron energy and the surface coverage were varied. The experiments reveal that solid acetonitrile is desorbed from its ultrathin solid films with a cross section of the order of 10{sup -17} cm{sup 2}. Evidence is presented for a significantly larger desorption cross section for acetonitrile molecules at the water-ice interface, similar to that previously observed for the benzene-water system.


    Institute of Scientific and Technical Information of China (English)

    YU Qingsong; YE Mu; LU Lizhen; CHEN Jie; WANG Fosong; Yoshihito Osada


    Plasma polymerization of acetonitrile was carried out by a capacitively coupled RF plasma apparatus with external electrodes under some different reaction conditions such as discharge power. By investigating the informations provided by the polymer deposition regularities, IR spectra and elementary analysis results,the polymerization mechanism of acetonitrile in glow discharge have been investigated. The results show that acetonitrile polymerized in glow discharge mainly through hydrogen detachment for initiation at lower energy levels and the role that opening C = N triple bond played in polymerization became more important at higher energy levels.


    An efficient microwave-assisted expoxidation of olefins is described over hydrotalcite catalysts in the presence of hydrogen peroxide and acetonitrile. This general and selective protocol is extremely fast and is applicable to a wide variety of subtrates.

  8. Crystal structure of cis-anti-cis-dicyclohexane-18-crown-6 acetonitrile disolvate

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    Alexander Nazarenko


    Full Text Available The title compound (systematic name: cis-anti-cis-2,5,8,15,18,21-hexaoxatricyclo[,14]hexacosane acetonitrile disolvate, C20H36O6·2CH3CN, crystallizes from an acetonitrile solution of dicyclohexane-18-crown-6 on evaporation. The molecule is arranged around a center of symmetry with half the crown ether molecule and one molecule of acetonitrile symmetry independent. All O—C—C—O torsion angles are gauche while all C—O—C—C angles are trans. The sequence of torsion angles is [(tg+t(tg−t]3; the geometry of oxygen atoms is close to pseudo-D3d with three atoms below and three atoms above the mean plane, with an average deviation of ±0.16 (1 Å from the mean plane. This geometry is identical to that observed in metal ion complexes of dicyclohexane-18-crown-6 but differs significantly from the conformation of a free unsolvated molecule. Each acetonitrile molecule connects to a crown ether molecule via two of its methyl group H atoms (C—H...O. Weaker interactions exist between the third H atom of the acetonitrile methyl group and an O atom of a neighbouring crown ether molecule (C—H...O; and between the N atom of the acetonitrile molecule and a H atom of another neighbouring crown ether molecule. All these intermolecular interactions create a three-dimensional network stabilizing the disolvate.

  9. [Effect of Acetonitrile and n-hexane on the Immunoassay of Environmental Representative Pollutants]. (United States)

    Lou, Xue-ning; Zhou, Li-ping; Song, Dan; Yang, Rong; Long, Feng


    Based on indirect competitive immunoassay mechanism, bisphenol A (BPA) was detected by the evanescent wave all-fiber immunosensor previously developed with the detection limit of 0.2 microg x L(-1) and the linear detection range of 0.3-33.4 microg x L(-1). The effects of two commonly used organic solvents, including acetonitrile and n-hexane, on the immunosensing assay of BPA were investigated. The influence mechanism of organic solvents on immunosensing assay was discussed. The experimental results showed that the effect of n-hexane on immunosensing assay was negligible even at a high concentration of up to 10%, whereas the effect of acetonitrile on the immunosensing assay was relatively great. BPA could be detected in solutions containing a low concentration of acetonitrile. However, the specific binding reaction between antibody and antigen in homogeneous solution was completely inhibited by high concentrations of acetonitrile, and the quantitative analysis of BPA was not achieved. This might result from the changes of antibody conformation or binding capability between antibody and antigen because acetonitrile replaced a part of the water molecules on the antibody surface.

  10. Aqueous Two-Phase Systems formed by Biocompatible and Biodegradable Polysaccharides and Acetonitrile. (United States)

    de Brito Cardoso, Gustavo; Souza, Isabela Nascimento; Pereira, Matheus M; Freire, Mara G; Soares, Cleide Mara Faria; Lima, Álvaro Silva


    In this work, it is shown that novel aqueous two-phase systems can be formed by the combination of acetonitrile and polysaccharides, namely dextran. Several ternary phase diagrams were determined at 25 °C for the systems composed of water + acetonitrile + dextran. The effect of the dextran molecular weight (6,000, 40,000 and 100,000 g.mol(-1)) was ascertained toward their ability to undergo liquid-liquid demixing. An increase in the dextran molecular weight favors the phase separation. Furthermore, the effect of temperature (25, 35 and 45 °C) was evaluated for the system constituted by the dextran of higher molecular weight. Lower temperatures are favorable for phase separation since lower amounts of dextran and acetonitrile are required for the creation of aqueous two-phase systems. In general, acetonitrile is enriched in the top phase while dextran is majorly concentrated in the bottom phase. The applicability of this new type of two-phase systems as liquid-liquid extraction approaches was also evaluated by the study of the partition behavior of a well-known antioxidant - vanillin - and used here as a model biomolecule. The optimized conditions led to an extraction efficiency of vanillin of 95% at the acetonitrile-rich phase.

  11. High-yield acetonitrile | water triple phase boundary electrolysis at platinised Teflon electrodes

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    Watkins, John D.; MacDonald, Stuart M.; Fordred, Paul S.; Bull, Steven D. [Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Gu, Yunfeng; Yunus, Kamran; Fisher, Adrian C. [Department of Chemical Engineering, University of Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA (United Kingdom); Bulman-Page, Philip C. [School of Chemistry, University of East Anglia, Norwich, Norfolk NR4 7TJ (United Kingdom); Marken, Frank [Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom)], E-mail:


    A dynamic acetonitrile | aqueous electrolyte phase boundary in contact with platinised Teflon working electrodes is investigated. High concentrations of salt in the aqueous phase (2 M NaCl and 0.1 M NaClO{sub 4}) ensure immiscibility and the polar nature of acetonitrile aids the formation of a well-behaved triple phase boundary reaction zone. The one-electron oxidation of tert-butylferrocene in the organic phase without intentionally added electrolyte is studied. The limiting current for the flowing triple phase boundary process is shown to be essentially volume flow rate independent. The process is accompanied by the transfer of perchlorate from the aqueous into the organic phase and the flux of anions is shown to be approximately constant along the dynamic acetonitrile | aqueous electrolyte | platinum line interface. A high rate of conversion (close to 100%) is achieved at slow volume flow rates and at longer platinum electrodes.

  12. The methyl torsional levels of solid acetonitrile (CH3CN)—A neutron scattering study (United States)

    Trevino, S. F.; Choi, C. S.; Neumann, D. A.


    Neutron powder diffraction has been used to obtain the thermal parameters for the deuterium atoms and to confirm the crystal structure of acetonitrile-d3 at 4 K. Inelastic neutron scattering from both isotopic species is used to determine the energies of the first and second rotational levels of the methyl group. These four levels are reasonably reproduced by a threefold potential with V3=125 meV. The activation energy derived from this potential is in agreement with that previously obtained from the temperature dependence of T1 in proton magnetic resonance measurements.

  13. Hydrogen-bonding interactions between [BMIM][BF4] and acetonitrile. (United States)

    Zheng, Yan-Zhen; Wang, Nan-Nan; Luo, Jun-Jie; Zhou, Yu; Yu, Zhi-Wu


    In this work, the interactions between a representative imidazolium-based ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) and acetonitrile (CH3CN) were investigated in detail using attenuated total reflection infrared spectroscopy (ATR-IR), hydrogen nuclear magnetic resonance ((1)H NMR), and density functional theory calculations. The main conclusions are: (1) a number of species in the [BMIM][BF4]-CH3CN mixtures were identified with the help of excess infrared spectroscopy and quantum chemical calculations. The dilution process of the ionic liquid by acetonitrile was found to be the transformation from ion clusters to ion pairs. (2) The solvent molecules cannot break apart the strong Coulombic interaction between [BMIM](+) and [BF4](-) but can break apart the ion cluster into an ion pair within the concentration range investigated. The strength of hydrogen bonds between the C-Hs of [BMIM](+) and the N of acetonitrile is enhanced during the dilution process. (3) The methyl group of CH3CN locates above/below the imidazolium ring in the solution. These in-depth studies on the properties of the ionic liquid-acetonitrile mixed solvents may shed light on exploring their applications as reaction media in electrochemistry and chemical synthesis.

  14. An alternative pathway for production of acetonitrile: ruthenium catalysed aerobic dehydrogenation of ethylamine

    DEFF Research Database (Denmark)

    Corker, Emily; Mentzel, Uffe Vie; Mielby, Jerrik Jørgen;


    The oxidative synthesis of acetonitrile from ethylamine was studied using a supported ruthenium catalyst. The reaction was conducted in both batch and flow processes and high conversions (over 85%) were achieved in both cases. Selectivity of both reactions was improved by optimisation of reaction...

  15. Theoretical studies on the anionic association of phenol and its derivatives in acetonitrile (United States)

    Wiśniewska, Marta; Makowski, Mariusz


    The potentials of mean force (PMF) were determined for homoconjugated systems of anionic complexes composed of phenol and its derivatives with their conjugate anionic bases in acetonitrile (ACN). For each acid-base pair studied, a series of umbrella-sampling molecular dynamics simulations using the AMBER force field with explicit solvent was carried out; the respective PMF was calculated using the Weighted Histogram Analysis Method (WHAM). Subsequently, association equilibrium constants were calculated by numerical integration of the PMF profiles. The PMF curves had a typical shape, i.e., a very deep and narrow contact-minimum, a desolvation maximum, and a shallow solvent-separated minimum. All pairs formed complexes in solution, which was confirmed by the presence of contact minima corresponding to the existence of hydrogen bonds in the PMF curves. The calculated association constants in acetonitrile were subsequently compared with experimentally obtained values for the same solvent. Ab initio methods at the RHF level (utilizing the Gaussian 6-31++G** basis set) enabled the in vacuo calculation of energies and Gibbs free energies of interaction for each phenol derivative and anionic base pair along with a molecule of acetonitrile; this allowed the contribution of the solvent molecule to the PMF to be assessed. It was found that the interaction energies of anionic bases in acetonitrile are stronger than their related neutral phenol derivatives.

  16. Liquid / liquid biphasic electrochemistry in ultra-turrax dispersed acetonitrile / aqueous electrolyte systems

    Energy Technology Data Exchange (ETDEWEB)

    Watkins, John D. [Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY (United Kingdom); Amemiya, Fumihiro; Atobe, Mahito [Tokyo Institute of Technology, Department of Electronic Chemistry, Yokohama, Kanagawa 2268502 (Japan); Bulman-Page, Philip C. [School of Chemistry, University of East Anglia, Norwich, Norfolk NR4 7TJ (United Kingdom); Marken, Frank, E-mail: [Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY (United Kingdom)


    Unstable acetonitrile | aqueous emulsions generated in situ with ultra-turrax agitation are investigated for applications in dual-phase electrochemistry. Three modes of operation for liquid / liquid aqueous-organic electrochemical processes are demonstrated with no intentionally added electrolyte in the organic phase based on (i) the formation of a water-soluble product in the aqueous phase in the presence of the organic phase, (ii) the formation of a product and ion transfer at the liquid / liquid-electrode triple phase boundary, and (iii) the formation of a water-insoluble product in the aqueous phase which then transfers into the organic phase. A three-electrode electrolysis cell with ultra-turrax agitator is employed and characterised for acetonitrile / aqueous 2 M NaCl two phase electrolyte. Three redox systems are employed in order to quantify the electrolysis cell performance. The one-electron reduction of Ru(NH{sub 3}){sub 6}{sup 3+} in the aqueous phase is employed to determine the rate of mass transport towards the electrode surface and the effect of the presence of the acetonitrile phase. The one-electron oxidation of n-butylferrocene in acetonitrile is employed to study triple phase boundary processes. Finally, the one-electron reduction of cobalticenium cations in the aqueous phase is employed to demonstrate the product transfer from the electrode surface into the organic phase. Potential applications in biphasic electrosynthesis are discussed.

  17. Structure of water + acetonitrile solutions from acoustic and positron annihilation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Jerie, Kazimierz [Institute of Experimental Physics, University of WrocIaw, WrocIaw (Poland); Baranowski, Andrzej [Institute of Experimental Physics, University of WrocIaw, WrocIaw (Poland); Koziol, Stan [Waters Corp., 34 Maple St., Milford, MA 01757 (United States); Glinski, Jacek [Faculty of Chemistry, University of WrocIaw, WrocIaw (Poland)]. E-mail:; Burakowski, Andrzej [Faculty of Chemistry, University of WrocIaw, WrocIaw (Poland)


    We report the results of acoustic and positron annihilation measurements in aqueous solutions of acetonitrile (CH{sub 3}CN). Hydrophobicity of the solute is discussed, as well as the possibility of describing the title system in terms of hydrophobic solvation. A new method of calculating the 'ideal' positronium lifetimes is proposed, based on the mean volume of cavities (holes) in liquid structure available for positronium pseudoatom. The results are almost identical with those obtained from molar volumes using the concept of Levay et al. On the other hand, the same calculations performed using the 'bubble' model of annihilation yield very different results. It seems that either acetonitrile forms with water clathrate-like hydrates of untypical architecture, or it is too weak hydrophobic agent to form clathrate-like hydrates at all. The former interpretation seems to be more probable.

  18. Structure of Aqueous Solutions of Acetonitrile Investigated by Acoustic and Positron Annihilation Measurements (United States)

    Jerie, K.; Baranowski, A.; Koziol, S.; Burakowski, A.


    We report the results of acoustic and positron annihilation measurements in aqueous solutions of acetonitrile (CH3CN). Hydrophobicity of the solute is discussed, as well as the possibility of describing the title system in terms of hydrophobic solvation. The concept of Levay et al. of calculating the "ideal positronium lifetimes is applied, basing on the mean volume of cavities (holes) in liquid structure available for positronium pseudoatom. The same calculations performed using the Tao model of annihilation yield very different results. It can be concluded that either acetonitrile forms with water clathrate-like hydrates of untypical architecture, or it is too weak hydrophobic agent to form clathrate-like hydrates at all. The former interpretation seems to be more probable.

  19. Structure of water + acetonitrile solutions from acoustic and positron annihilation measurements (United States)

    Jerie, Kazimierz; Baranowski, Andrzej; Koziol, Stan; Gliński, Jacek; Burakowski, Andrzej


    We report the results of acoustic and positron annihilation measurements in aqueous solutions of acetonitrile (CH 3CN). Hydrophobicity of the solute is discussed, as well as the possibility of describing the title system in terms of hydrophobic solvation. A new method of calculating the "ideal" positronium lifetimes is proposed, based on the mean volume of cavities (holes) in liquid structure available for positronium pseudoatom. The results are almost identical with those obtained from molar volumes using the concept of Levay et al. On the other hand, the same calculations performed using the "bubble" model of annihilation yield very different results. It seems that either acetonitrile forms with water clathrate-like hydrates of untypical architecture, or it is too weak hydrophobic agent to form clathrate-like hydrates at all. The former interpretation seems to be more probable.

  20. Spectrophotometric determination of acidity constants of some macrolides in acetonitrile-water binary mixtures. (United States)

    Sanli, Senem; Sanli, Nurullah; Alsancak, Güleren


    The acidity constants of eight macrolides (erythromycin, roxithromycin, oleandomycin, azithromycin, josamycin, tylosin tartrate, tilmicosin and spiramycin) have been determined in acetonitrile-water binary mixtures (30%, 40% and 50% (v/v)) by spectrophotometric method. The pKa's available in literature determined by various methods are compiled in comparison with the value of this work. These results are expected to essentially facilitate the research on occurrence, fate and effects, analysis method development, and control of antibiotics in various treatment occurrences.

  1. Sorption of adamantane phenylamide derivatives on hyper-cross-linked polystyrene from water-acetonitrile eluents (United States)

    Shafigulin, R. V.; Konstantinov, A. V.; Bulanova, A. V.; Il'in, M. M.; Davankov, V. A.


    Study of the main physicochemical features of the sorption of phenylamide adamantane derivatives on hyper-cross-linked polystyrene from water-acetonitrile solutions shows that both hydrophobic and electronic interactions make a large contribution to retention, especially for a chlorine-containing derivative in which there are π- p and π- d interactions between the outer-shell electrons of the chlorine atom in addition to π- π interactions between aromatic fragments of the sorbate and sorbent.

  2. Sorption of substituted indoles on highly cross-linked polystyrene from water-acetonitrile solutions (United States)

    Shafigulin, R. V.; Myakishev, A. A.; Il'Ina, E. A.; Il'in, M. M.; Davankov, V. A.; Bulanova, A. V.


    The sorption of first synthesized indole derivatives by highly cross-linked polystyrenes from water-acetonitrile solutions was studied by high-performance liquid chromatography. The retention factors and differences in the Gibbs energy of adsorption from infinite diluted solutions were calculated, and the applicability of the Snyder-Soczewinski and Scott-Kucera models for describing the chromatographic retention of sorbates on a polymer network of highly cross-linked polystyrene was shown.

  3. Competitive solvation of (bis)(trifluoromethanesulfonyl)imide anion by acetonitrile and water

    DEFF Research Database (Denmark)

    Chaban, Vitaly


    Competitive solvation of an ion by two or more solvents is one of the key phenomena determining the identity of our world. Solvation in polar solvents frequently originates from non-additive non-covalent interactions. Pre-parametrized potentials poorly capture these interactions, unless the force...... and temperature coupling. Using a competitive solvation of (bis)(trifluoromethanesulfonyl)imide anion in acetonitrile and water, the work demonstrates efficiency and robustness of PM7-MD. (C) 2014 Elsevier B.V. All rights reserved....

  4. Computer simulation of acetonitrile and methanol with ab initio-based pair potentials (United States)

    Hloucha, M.; Sum, A. K.; Sandler, S. I.


    This study address the adequacy of ab initio pair interaction energy potentials for the prediction of macroscopic properties. Recently, Bukowski et al. [J. Phys. Chem. A 103, 7322 (1999)] performed a comprehensive study of the potential energy surfaces for several pairs of molecules using symmetry-adapted perturbation theory. These ab initio energies were then fit to an appropriate site-site potential form. In an attempt to bridge the gap between ab initio interaction energy information and macroscopic properties prediction, we performed Gibbs ensemble Monte Carlo (GEMC) simulations using their developed pair potentials for acetonitrile and methanol. The simulations results show that the phase behavior of acetonitrile is well described by just the pair interaction potential. For methanol, on the other hand, pair interactions are insufficient to properly predict its vapor-liquid phase behavior, and its saturated liquid density. We also explored simplified forms for representing the ab initio interaction energies by refitting a selected range of the data to a site-site Lennard-Jones and to a modified Buckingham (exponential-6) potentials plus Coulombic interactions. These were also used in GEMC simulations in order to evaluate the quality and computational efficiency of these different potential forms. It was found that the phase behavior prediction for acetonitrile and methanol are highly dependent on the details of the interaction potentials developed.

  5. Interaction of counterions with subtilisin in acetonitrile: insights from molecular dynamics simulations. (United States)

    Lousa, Diana; Cianci, Michele; Helliwell, John R; Halling, Peter J; Baptista, António M; Soares, Cláudio M


    A recent X-ray structure has enabled the location of chloride and cesium ions on the surface of subtilisin Carlsberg in acetonitrile soaked crystals. (1) To complement the previous study and analyze the system in solution, molecular dynamics (MD) simulations, in acetonitrile, were performed using this structure. Additionally, Cl(-) and Cs(+) ions were docked on the protein surface and this system was also simulated. Our results indicate that chloride ions tend to stay close to the protein, whereas cesium ions frequently migrate to the solvent. The distribution of the ions around the enzyme surface is not strongly biased by their initial locations. Replacing cesium by sodium ions showed that the distribution of the two cations is similar, indicating that Cs(+) can be used to find the binding sites of cations like Na(+) and K(+), which, unlike Cs(+), have physiological and biotechnological roles. The Na(+)Cl(-) is more stable than the Cs(+)Cl(-) ion pair, decreasing the probability of interaction between Cl(-) and subtilisin. The comparison of water and acetonitrile simulations indicates that the solvent influences the distribution of the ions. This work provides an extensive theoretical analysis of the interaction between ions and the model enzyme subtilisin in a nonaqueous medium.

  6. A time-resolved resonance Raman study of chlorine dioxide photochemistry in water and acetonitrile

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, S.C.; Philpott, M.P.; Mayer, S.G.; Reid, P.J. [Univ. of Washington, Seattle, WA (United States). Dept. of Chemistry


    The photochemistry of chlorine dioxide (OClO) has attracted much interest due to its participation in the atmospheric chlorine reservoir as well as its potential role in stratospheric ozone depletion. Since the environmental impact of OClO arises from its ability to produce atomic chlorine, understanding this phase-dependent reactivity is essential if models capable of predicting the environmental impact of OClO in both homogeneous and heterogeneous settings are to be obtained. The photochemistry of chlorine dioxide (OClO) in water and acetonitrile is investigated using time-resolved resonance Raman spectroscopy. Stokes and anti-Stokes spectra are measured as a function of time following photoexcitation using degenerate pump and probe wavelengths of 390 nm. For aqueous OClO, the time-dependent Stokes intensities are found to be consistent with the re-formation of ground-state OClO by subpicosecond geminate recombination of the primary ClO and O photofragments. This represents the first unequivocal demonstration of primary-photoproduct geminate recombination in the condensed-phase photochemistry of OClO. Anti-Stokes intensity corresponding to the OClO symmetric stretch is observed demonstrating that, following geminate recombination, excess vibrational energy is deposited along this coordinate. Analysis of the anti-Stokes decay kinetics demonstrates that, in water, intermolecular vibrational relaxation occurs with a time constant of {approximately}9 ps. For OClO dissolved in acetonitrile, the Stokes scattering intensities are consistent with a significant reduction in the geminate-recombination quantum yield relative to water. Comparison of the OClO anti-Stokes decay kinetics in acetonitrile and water demonstrates that the rate of intermolecular vibrational relaxation is {approximately}4 times smaller in acetonitrile. Finally, in both solvents the appearance of symmetric-stretch anti-Stokes intensity is significantly delayed relative to geminate recombination. This

  7. Acetonitrile shortage: use of isopropanol as an alternative elution system for ultra/high performance liquid chromatography† (United States)

    Desai, Ankur M.; Andreae, Mark; Mullen, Douglas G.; Holl, Mark M. Banaszak; Baker, James R.


    Acetonitrile is a choice of solvent for almost all chromatographic separations. In recent years, researchers around the globe have faced an acetonitrile shortage that affected routine analytical operations. Researchers have tried to counter this shortage by applying many innovative solutions, including using ultra performance liquid chromatography (UPLC) columns that are shorter and smaller in diameter than traditional high performance liquid chromatography (HPLC) columns, thus significantly decreasing the volume of eluent required. Although utilizing UPLC in place of HPLC can alleviate the solvent demand to some extent, acetonitrile is generally thought of as the solvent of choice due to its versatility. In the following communication, we describe an alternative eluent system that uses isopropanol in place of acetonitrile as an organic modifier for routine chromatographic separations. We report here the development of an isopropanol based UPLC protocol for G5 PAMAM dendrimer based conjugates that was transferred to semi-preparative applications. PMID:21572563

  8. The alcoholysis of acetonitrile prompted by Br(o)nsted acidic ionic liquid [HSO3-pmim]HSO4

    Institute of Scientific and Technical Information of China (English)

    Dong Jiang; Yuan Yuan Wang; Ming Tu; Li Yi Dai


    Br(o)nsted acidic ionic liquids based on imidazolium cation were employed as a series of environmentally benign catalysts and mediums in the alcoholysis of acetonitrile to synthesize ester. The results showed that Br(o)nsted acidic ionic liquid [HSO3-pmim]HSO4 was an efficient catalyst and medium for the alcoholysis of acetonitrile which could be recycled easily without obvious decline in catalytic activity, the highest yield could reach 85%.

  9. Strategies for the hyperpolarization of acetonitrile and related ligands by SABRE. (United States)

    Mewis, Ryan E; Green, Richard A; Cockett, Martin C R; Cowley, Michael J; Duckett, Simon B; Green, Gary G R; John, Richard O; Rayner, Peter J; Williamson, David C


    We report on a strategy for using SABRE (signal amplification by reversible exchange) for polarizing (1)H and (13)C nuclei of weakly interacting ligands which possess biologically relevant and nonaromatic motifs. We first demonstrate this via the polarization of acetonitrile, using Ir(IMes)(COD)Cl as the catalyst precursor, and confirm that the route to hyperpolarization transfer is via the J-coupling network. We extend this work to the polarization of propionitrile, benzylnitrile, benzonitrile, and trans-3-hexenedinitrile in order to assess its generality. In the (1)H NMR spectrum, the signal for acetonitrile is enhanced 8-fold over its thermal counterpart when [Ir(H)2(IMes)(MeCN)3](+) is the catalyst. Upon addition of pyridine or pyridine-d5, the active catalyst changes to [Ir(H)2(IMes)(py)2(MeCN)](+) and the resulting acetonitrile (1)H signal enhancement increases to 20- and 60-fold, respectively. In (13)C NMR studies, polarization transfers optimally to the quaternary (13)C nucleus of MeCN while the methyl (13)C is hardly polarized. Transfer to (13)C is shown to occur first via the (1)H-(1)H coupling between the hydrides and the methyl protons and then via either the (2)J or (1)J couplings to the respective (13)Cs, of which the (2)J route is more efficient. These experimental results are rationalized through a theoretical treatment which shows excellent agreement with experiment. In the case of MeCN, longitudinal two-spin orders between pairs of (1)H nuclei in the three-spin methyl group are created. Two-spin order states, between the (1)H and (13)C nuclei, are also created, and their existence is confirmed for Me(13)CN in both the (1)H and (13)C NMR spectra using the Only Parahydrogen Spectroscopy protocol.

  10. Assembly of an allenylidene ligand, a terminal alkyne, and an acetonitrile molecule: formation of osmacyclopentapyrrole derivatives. (United States)

    Bolaño, Tamara; Castarlenas, Ricardo; Esteruelas, Miguel A; Oñate, Enrique


    Treatment in acetonitrile at -30 C of the hydride-alkenylcarbyne complex [OsH([triple bond]CCH=CPh2)(CH3CN)2(P(i)Pr3)2][BF4]2 (1) with (t)BuOK produces the selective deprotonation of the alkenyl substituent of the carbyne and the formation of the bis-solvento hydride-allenylidene derivative [OsH(=C=C=CPh2)(CH3CN)2(P(i)Pr3)2]BF4 (2), which under carbon monoxide atmosphere is converted into [Os(CH=C=CPh2)(CO)(CH3CN)2(P(i)Pr3)2]BF4 (3). When the treatment of 1 with (t)BuOK is carried out in dichloromethane at room temperature, the fluoro-alkenylcarbyne [OsHF([triple bond]CCH=CPh2)(CH3CN)(P(i)Pr3)2]BF4 (4) is isolated. Complex 2 reacts with terminal alkynes. The reactions with phenylacetylene and cyclohexylacetylene afford [Os[(E)-CH=CHR](=C=C=CPh2)(CH3CN)2(P(i)Pr3)2]BF4 (R = Ph (5), Cy (6)), containing an alkenyl ligand beside the allenylidene, while the reaction with acetylene in dichloromethane at -20 degrees C gives the hydride-allenylidene-pi-alkyne [OsH(=C=C=CPh2)(eta2-HC[triple bond]CH)(P(i)Pr3)2]BF4 (7), with the alkyne acting as a four-electron donor ligand. In acetonitrile under reflux, complexes 5 and 6 are transformed into the osmacyclopentapyrrole compounds [Os[C=C(CPh2CR=CH)CMe=NH](CH3CN)2]BF4 (R = Ph (8), Cy (9)), as a result of the assembly of the allenylidene ligand, the alkenyl group, and an acetonitrile molecule. The X-ray structures of 2, 5, and 8 are also reported.

  11. Effects of organic solvents and substrate binding on trypsin in acetonitrile and hexane media. (United States)

    Meng, Yanyan; Yuan, Yuan; Zhu, Yanyan; Guo, Yanzhi; Li, Menglong; Wang, Zhimeng; Pu, Xuemei; Jiang, Lin


    In this work, we used molecular dynamic (MD) simulation to study trypsin with and without a six-amino-acid peptide bound in three different solvents (water, acetonitrile and hexane) in order to provide molecular information for well understanding the structure and function of enzymes in non-aqueous media. The results show that the enzyme is more compact and less native-like in hexane than in the other two polar solvents. The substrate could stabilize the native protein structure in the two polar media, but not in the non-polar hexane. There are no significant differences in the conformation of the S1 pocket upon the substrate binding in water and acetonitrile media while a reverse behavior is observed in hexane media, implying a possible induced fit binding mechanism in the non-polar media. The substrate binding enhances the stability of catalytic H-bond network since it could expel the solvent molecules from the active site. The enzyme and the substrate appear to be more appropriate to the reactive conformation in the organic solvents compared with aqueous solution. There is much greater substrate binding strength in hexane media than the water and acetonitrile ones since the polar solvent significantly weakens electrostatic interactions, which are observed to be the main driving force to the binding. In addition, some residues of the S1 pocket could remain favorable contribution to the binding despite the solvent change, but with differences in the contribution extent, the number and the type of residues between the three media.

  12. Acetonitrile and N-Chloroacetamide Formation from the Reaction of Acetaldehyde and Monochloramine. (United States)

    Kimura, Susana Y; Vu, Trang Nha; Komaki, Yukako; Plewa, Michael J; Mariñas, Benito J


    Nitriles and amides are two classes of nitrogenous disinfection byproducts (DBPs) associated with chloramination that are more cytotoxic and genotoxic than regulated DBPs. Monochloramine reacts with acetaldehyde, a common ozone and free chlorine disinfection byproduct, to form 1-(chloroamino)ethanol. Equilibrium (K1) and forward and reverse rate (k1,k-1) constants for the reaction between initial reactants and 1-(chloroamino)ethanol were determined between 2 and 30 °C. Activation energies for k1 and k-1 were 3.04 and 45.2 kJ·mol(-1), respectively, and enthalpy change for K1 was -42.1 kJ·mol(-1). In parallel reactions, 1-(chloroamino)ethanol (1) slowly dehydrated (k2) to (chloroimino)ethane that further decomposed to acetonitrile and (2) was oxidized (k3) by monochloramine to produce N-chloroacetamide. Both reactions were acid/base catalyzed, and rate constants were characterized at 10, 18, and 25 °C. Modeling for drinking water distribution system conditions showed that N-chloroacetamide and acetonitrile concentrations were 5-9 times higher at pH 9.0 compared to 7.8. Furthermore, acetonitrile concentration was found to form 7-10 times higher than N-chloroacetamide under typical monochloramine and acetaldehyde concentrations. N-chloroacetamide cytotoxicity (LC50 = 1.78 × 10(-3) M) was comparable to dichloroacetamide and trichloroacetamide, but less potent than N,2-dichloroacetamide and chloroacetamide. While N-chloroacetamide was not found to be genotoxic, N,2-dichloroacetamide genotoxic potency (5.19 × 10(-3) M) was on the same order of magnitude as chloroacetamide and trichloroacetamide.

  13. Intermolecular orientations in liquid acetonitrile: new insights based on diffraction measurements and all-atom simulations

    CERN Document Server

    Pothoczki, Szilvia


    Intermolecular correlations in liquid acetonitrile (CH3CN) have been revisited by calculating orientational correlation functions. In the present approach, hydrogen atoms are included, so that a concept applicable for molecules of (nearly) tetrahedral shape can be exploited. In this way molecular arrangements are elucidated not only for closest neighbours but also extending well beyond the first coordination sphere. Thus a complementary viewpoint is provided to the more popular dipole-dipole correlations. Our calculations are based on large structural models that were obtained by applying diffraction data and partial radial distribution functions from potential-based (all-atom) molecular dynamics simulation simultaneously, within the framework of the Reverse Monte Carlo method.

  14. Elemental step thermodynamics of various analogues of indazolium alkaloids to obtaining hydride in acetonitrile. (United States)

    Lei, Nan-Ping; Fu, Yan-Hua; Zhu, Xiao-Qing


    A series of analogues of indazolium alkaloids were designed and synthesized. The thermodynamic driving forces of the 6 elemental steps for the analogues of indazolium alkaloids to obtain hydride in acetonitrile were determined using an isothermal titration calorimeter (ITC) and electrochemical methods, respectively. The effects of molecular structure and substituents on the thermodynamic driving forces of the 6 steps were examined. Meanwhile, the oxidation mechanism of NADH coenzyme by indazolium alkaloids was examined using the chemical mimic method. The result shows that the oxidation of NADH coenzyme by indazolium alkaloids in vivo takes place by one-step concerted hydride transfer mechanism.

  15. Ultrasonic Investigations of Molecular Interaction in Binary Mixtures of Benzyl Benzoate with Acetonitrile and Benzonitrile

    Directory of Open Access Journals (Sweden)

    N. Jaya Madhuri


    Full Text Available Ultrasonic velocity, density and viscosity have been measured in the binary mixtures of benzyl benzoate with acetonitrile, benzonitrile at three temperatures 30, 40 and 50 °C. From the experimental data, thermodynamic parameters like adiabatic compressibility, internal pressure, enthalpy, activation energy etc., were computed and the molecular interactions were predicted based on the variation of excess parameters in the mixture. Also theoretical evaluation of velocities was made employing the standard theories. CFT and NOMOTO were found to have an edge. All the three mixtures have shown out strong intermolecular interactions between the unlike molecules and endothermic type of chemical reaction.

  16. Chlorido(1,3-dimethylthiourea-κSbis(triphenylphosphine-κPcopper(I acetonitrile hemisolvate

    Directory of Open Access Journals (Sweden)

    Brian W. Skelton


    Full Text Available The title compound, [CuCl(C3H8N2S(C18H15P2]·0.5CH3CN, was prepared by the reaction of copper(I chloride with 1,3-dimethylthiourea (dmtu and triphenylphosphine (PPh3 in acetonitrile. The CuI atom has a distorted tetrahedral environment formed by two P atoms from triphenylphosphine, one S atom from the dmtu ligand and one Cl atom. In addition, the molecules exhibit intra- and intermolecular N—H...Cl interactions.

  17. A tetranuclear cadmium(II) complex based on the 2-(quinolin-8-yloxy)acetonitrile ligand. (United States)

    Liu, Ming-Liang; Ye, Qiong


    The hydrothermal reaction of 2-(quinolin-8-yloxy)acetonitrile and Cd(ClO(4))(2) yielded the noncentrosymmetric coordination complex tetrakis[μ-2-(quinolin-8-yloxy)acetato]tetrakis[μ-2-(quinolin-8-yloxy)acetonitrile]tetracadmium tetrakis(perchlorate) dihydrate, [Cd(4)(C(11)H(8)NO(3))(4)(C(11)H(8)N(2)O)(4)](ClO(4))(4)·2H(2)O. The local coordination environment around the Cd(II) cation can be best described as a capped octahedron defined by two N atoms and five O atoms from three ligands. The Cd(II) cations are linked by the ligands with Cd-O-Cd and Cd-O-C-C-O-Cd bridges, forming tetranuclear units, there being two independent tertranuclear units in the structure. The fourfold rotoinversion centre sits at the centre of each Cd(4) core. The two perchlorate anions in the asymmetric unit are linked by the water molecule through O-H...O hydrogen bonds.

  18. Infrared electroabsorption spectroscopy of N,N-dimethyl-p-nitroaniline in acetonitrile/C2Cl4: solvation of the solute and self-association of acetonitrile. (United States)

    Wang, Wei-Chieh; Shigeto, Shinsuke


    Solvated structures of N,N-dimethyl-p-nitroaniline (DMPNA), an analog of p-nitroaniline (PNA), and self-associated structures of acetonitrile (ACN) in mixed solvents of ACN and C(2)Cl(4) were studied using infrared (IR) electroabsorption and FTIR spectroscopies. IR electroabsorption spectroscopy measures changes in IR absorption intensity upon application of external electric field modulation, which are a sensitive probe for permanent dipole moments. In ACN/CCl(4), PNA has been shown to occur as two distinct solvated forms, namely, 1:1 and 1:2 forms, which have one and two ACN molecule(s), respectively, associated with PNA. The IR electroabsorption and FTIR measurements on DMPNA show that, unlike PNA, DMPNA occurs as a monomer in ACN/C(2)Cl(4) rather than as specific solvated structures analogous to the 1:1 and 1:2 forms because of the substitution effect. Not only does the N,N-dimethyl substitution in DMPNA hamper solvation of ACN at the N(CH(3))(2) group, but it also indirectly blocks strong interactions with ACN at the NO(2) group. Furthermore, by using the ΔA signal of DMPNA as an internal intensity standard, it was found that the dipole moment of ACN in the DMPNA/ACN/C(2)Cl(4) system is about 1.5 times larger than that of the ACN monomer in dilute CCl(4) solution. This large value of the dipole moment in the solution studied here is attributable to the formation of a head-to-tail linear dimer of ACN, whereas the antiparallel dimer is energetically more favorable in the gas phase.

  19. Interaction of acetonitrile with Na-zeolites: adsorption modes and vibrational dynamics in the zeolite channels and cavities. (United States)

    Nachtigallová, Dana; Vrbka, L; Bludský, O; Nachtigall, P


    The interaction of acetonitrile with the extra-framework Na(+) cations in zeolites, namely Na-LTA and Na-FER, was investigated. The relative stabilities of possible types of adsorption complexes were calculated at the periodic DFT level. Individual effects on the complex stability and on the vibrational dynamics of adsorbed acetonitrile were qualitatively analysed on various cluster models. The acetonitrile primarily interacts with the Na(+) cation (via the N end), and the complex stability is modulated by the interaction of the methyl group with the framework oxygen atoms, which has a partial hydrogen-bond character. In line with the results of recent analyses of CO interactions with metal-exchanged zeolites [D. Nachtigallová, O. Bludský, C. O. Areán, R. Bulanek and P. Nachtigall, Phys. Chem. Chem. Phys., 2006, 8, 4849], two types of effects should be taken into consideration for acetonitrile complexes in Na-zeolites: (i) the effects from the bottom, reflecting the accessibility and coordination of the primary metal cation, to which the acetonitrile molecule is bonded via the N atom; and (ii) the effects from the top, including H-bond formation (stabilising effect) or repulsion due to the secondary metal cation. The effect from the bottom results in a blue shift of nu(CN) while the effect from the top (H-bond formation) results in a red shift in both nu(CN) and nu(CH).

  20. Electrochemical study of 7{alpha},12,20-O-trimethyl-conacytone in acetonitrile

    Energy Technology Data Exchange (ETDEWEB)

    Frontana, Carlos; Frontana-Uribe, Bernardo A.; Gonzalez, Ignacio


    An electrochemical study of the electroreduction in anhydrous acetonitrile of 7{alpha},12,20-O-trimethyl-conacytone, an abietane quinoid diterpene derivative from the natural product 7{alpha}-O-methyl-conacytone, showed two reduction signals. At the first reduction step, fast chemical reactions involving the loss of the methoxyl group located at C-7 with simultaneous regeneration of the quinoid moiety were observed. This electrogenerated quinone is reduced again, at the same potential used with the former quinone, resulting in a two-electron peak. These results were obtained by cyclic voltammetry and double-step chronoamperometry experiments. The electrolysis under methylating conditions of 7{alpha}-O-methyl-conacytone, at potential values of the second electron transfer, generates as major products, methoxy-hydroquinone, where the methoxy group at C-7 is lost, which is in agreement with the proposed mechanism. Therefore, the second reduction signal was attributed to the reduction of semiquinone intermediates by a mechanism not elucidated.

  1. Solid form of indapamide recrystallized from acetonitrile/diethyl ether solvent mixture (United States)

    Rus, Lucia M.; Kacso, Irina; Borodi, Gheorghe; Aluas, Mihaela; Tomuta, Ioan; Iuga, Cristina; Simon, Simion; Bratu, Ioan; Bojita, Marius


    Indapamide (IDP) is a non-thiazide sulphonamide diuretic drug generally used for the treatment of essential hypertension. The aim of this work was to obtain and to characterize new solid forms of IDP. In this respect, the recrystallization of IDP from different solvent or solvent mixtures was carried out. Thermoanalytical techniques (differential scanning calorimetry (DSC) and thermogravimetry (TG)), X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR), solid state nuclear magnetic resonance (NMR) spectroscopy and scanning electron microscopy (SEM) were used for structural characterization of the new obtained solid forms. Based on the results of these techniques we can conclude that IDP recrystallized from acetonitrile+ diethyl ether solvent mixture presents a different structure and physical properties as compared with the starting IDP.

  2. Di-μ-perchlorato-bis{μ-2-[(2-pyridylmethylaminomethyl]phenolatodicopper(II acetonitrile disolvate

    Directory of Open Access Journals (Sweden)

    Gervas E. Assey


    Full Text Available In the crystal of the dinuclear title compound, [Cu2(C13H13N2O2(ClO42]·2CH3CN, the two bridging perchlorate ions chelate to the two CuII atoms in a μ-O:O′ fashion on opposite sides of the equatorial plane. The CuII ions display a distorted octahedral coordination geometry (in the usual 4 + 2 Jahn–Teller arrangement, each being coordinated by two O atoms from the two perchlorate ligands, and two N and O atoms from the reduced Schiff base ligand. The asymmetric unit contains two acetonitrile solvent molecules. In the crystal structure, in addition to N—H...O hydrogen bonds, there are weak C—H...O interactions between the perchlorate O atoms and the reduced Schiff base ligand. C—H...N interactions are also present.

  3. Heterolytic and Homolytic N-NO Bond Dissociation Energies of N-Nitroso-benzenesulfonylmethylamines in Acetonitrile

    Institute of Scientific and Technical Information of China (English)

    HAO Wei-Fang; Tang Hui; ZHU Xiao-Qing; CHENG Jin-Pei


    @@ Great interests have been accumulated in recent years in the chemistry and biochemistry of nitric oxide (NO) since the remarkable discoveries of its key roles in a wide range of human physiological processes. To elucidate the mechanistic details of NO migration from its donor to its acceptor, it is necessary to determine the Y-NO bind energy that registers the thermodynamic driving force for NO release and capture. In this paper the heterolytic and homolytic N-NO bond dissociation energies [ i. e., △Hhet(N-NO) and △Hhomo(N-NO)] for ten N-nitroso-p-substituted-benzensulfonyl methylamines in acetonitrile are offered, which were obtained from titration calorimetry and thermodynamic cycles, respectively (Scheme 1).

  4. Vibrational Relaxation of the Aqueous Proton in Acetonitrile: Ultrafast Cluster Cooling and Vibrational Predissociation. (United States)

    Ottosson, N; Liu, L; Bakker, H J


    We study the ultrafast O-H stretch vibrational relaxation dynamics of protonated water clusters embedded in a matrix of deuterated acetonitrile, using polarization-resolved mid-IR femtosecond spectroscopy. The clusters are produced by mixing triflic (trifluoromethanesulfonic) acid and H2O in molar ratios of 1:1, 1:2, and 1:3, thus varying the degree of hydration of the proton. At all hydration levels the excited O-H stretch vibration of the hydrated proton shows an ultrafast vibrational relaxation with a time constant T1 cooling of the clusters reveals a long-living, underlying transient absorption change with high anisotropy. We argue that this feature stems from the vibrational predissociation of a small fraction of the proton hydration structures, directly following the ultrafast infrared excitation.

  5. Transient IR spectroscopy and ab initio calculations on ESIPT in 3-hydroxyflavone solvated in acetonitrile. (United States)

    Chevalier, Katharina; Wolf, Matthias M N; Funk, Andreas; Andres, Marko; Gerhards, Markus; Diller, Rolf


    Femtosecond polarization resolved UV/Vis and mid-infrared spectroscopy was used to thoroughly identify and characterize the relevant elementary chemical and physical processes in the photocycle of 3-hydroxyflavone (3-HF) in solution. In one set of experiments with the polar aprotic solvent acetonitrile-d(3), for the first time excited state intramolecular proton transfer (ESIPT), vibrational cooling/relaxation and rotational diffusion could be separated, and furthermore mid IR vibrational spectra of 3-HF excited states in solution phase were obtained. UV/Vis transient absorption data yield the time constant τ(Rot) = 22 ps for rotational diffusion and the time constant τ(VR) = 8.5 ps for vibrational cooling/relaxation in the tautomer excited state (S(1)'). Biphasic ESIPT with τ ps as well as slow ground state recovery with τ > 500 ps was found. The time resolved mid IR data yield a time constant of ≈3.4 ps for the slow ESIPT step as well as the vibrational frequencies of S(0,) S(1)' and, in particular those of the short lived excited state S(1). Via quantum chemical calculations, structural parameters of these states are obtained. Various models were used, namely for the isolated molecule, aggregates with solvent as well as a polarizable continuum, that allow us to correlate the two ESIPT components with two mechanisms. Results are compared to those from previously published gas-phase experiments and indicate that the observed slow ESIPT is mediated by solute-solvent interaction via a hydrogen bond with the hydroxyl group of 3-HF.

  6. New method for the photo-chemiluminometric determination of benzoylurea insecticides based on acetonitrile chemiluminescence. (United States)

    Gil García, M D; Martínez Galera, M; Santiago Valverde, R


    The viability of tandem photochemical reaction-chemiluminescence detection has been studied for the determination of five benzoylurea insecticides, namely, diflubenzuron, triflumuron, hexaflumuron, lufenuron and flufenoxuron. The 'on-line' photochemical reaction of benzoylurea pesticides provides an enhanced chemiluminescence response of the pesticides during their oxidation by potassium hexacyanoferrate(III) and sodium hydroxide, whose signal increases with the percentage of acetonitrile in the reaction medium. The determination was performed using a photoreactor consisting of a PFA (perfluoroalkoxy) tube reactor coil (5 mx1.6-mm O.D. and 0.8-mm I.D.) and an 8-W xenon lamp. As the yield of the photoderivatization process and the chemiluminescent signals depend on the percentage of acetonitrile, the chromatographic column (a Gemini C18, Phenomenex 150 mmx4.6 mm, 5-microm particle size) was chosen with the aim of using high percentages of this organic solvent in the mobile phase. Previous studies showed that the rate of the chemiluminescent reaction was very fast. Therefore, a modification was carried out in the detector in order to mix the analytes and reactants as near as possible to the measure cell. The optimised method was validated with respect to linearity, precision, limits of detection and quantification accuracy. Under the optimised conditions, linear working range extends three orders of magnitude with the relative standard deviation of intra-day precision below 10% and detection limits between 0.012 and 0.18 microg mL-1, according to the compound. The proposed method has been successfully applied to the determination of benzoylureas in cucumber with good results.

  7. Direct Electrochemical Evidence of the Dissociation and Adsorption Behavior of Acetonitrile at Gold Electrodes by Ultrafast Voltammetry

    Institute of Scientific and Technical Information of China (English)


    Ultrafast cyclic voltammetry was used to study the redox behavior of a gold electrode in acetonitrile. The direct electrochemical evidence of the dissociation and adsorption behavior of acetonitrile at gold electrodes was found. It could be stated that two consecutive redox paths are involved, each with a special adsorption state acting as the reaction intermediate. The mean value,obtained of the electron-transfer rate constant of the second path, was 1.3 × 105 s-1 with a standard deviation of 0.24 × 105 s-1.

  8. Diacetonitrile[N,N′-bis(2,6-diisopropylphenylethane-1,2-diimine]dichloridochromium(II acetonitrile solvate

    Directory of Open Access Journals (Sweden)

    Stephan Peitz


    Full Text Available The title compound, [CrCl2(CH3CN2(C26H36N2]·CH3CN, was synthesized by the reaction of CrCl2(THF2 with N,N′-bis(2,6-diisopropylphenylethane-1,2-diimine in dichloromethane/acetonitrile. The chromium center is coordinated by two N atoms of the chelating diimine ligand, two chloride ions in a trans configuration with respect to each other, and by two N atoms of two acetonitrile molecules in a distorted octahedral geometry.

  9. Determination of the Dissociation Constant of Some Substituted Phenols by Potentiometric Method in Acetonitrile-Water Mixtures


    Ertokuş, Güzide Pekcan; Ahmet Hakan AKTAŞ


    Abstract: The dissociation constants of phenol, 2−methylphenol, 3−methylphenol, 4−methylphenol, and 4−ethylphenol have been determined by potentiometric titration in a electrochemical cell with glass electrode at 25 oC in water and in the mixtures of acetonitrile and water where the following volume fractions (before mixing) of acetonitrile were used: 0.10, 0.20, and 0.30. The ionic strength of the solutions was adjusted to be 0.1 mol dm−3 using KCl. The dissociation constants were ...

  10. A New Look at the Stability of Dimethyl Sulfoxide and Acetonitrile in Li-O2 Batteries

    DEFF Research Database (Denmark)

    Younesi, Reza; Norby, Poul; Vegge, Tejs


    Dimethyl sulfoxide (DMSO) and acetonitrile (MeCN) have recently been highlighted as promising electrolyte solvents for Li-O2 batteries. Possible reactions between these two solvents and Li2O2 are here discussed using X-ray photoelectron spectroscopy to analyze surface of the Li2O2 powder after...

  11. Theoretical analysis of co-solvent effect on the proton transfer reaction of glycine in a water-acetonitrile mixture. (United States)

    Kasai, Yukako; Yoshida, Norio; Nakano, Haruyuki


    The co-solvent effect on the proton transfer reaction of glycine in a water-acetonitrile mixture was examined using the reference interaction-site model self-consistent field theory. The free energy profiles of the proton transfer reaction of glycine between the carboxyl oxygen and amino nitrogen were computed in a water-acetonitrile mixture solvent at various molar fractions. Two types of reactions, the intramolecular proton transfer and water-mediated proton transfer, were considered. In both types of the reactions, a similar tendency was observed. In the pure water solvent, the zwitterionic form, where the carboxyl oxygen is deprotonated while the amino nitrogen is protonated, is more stable than the neutral form. The reaction free energy is -10.6 kcal mol(-1). On the other hand, in the pure acetonitrile solvent, glycine takes only the neutral form. The reaction free energy from the neutral to zwitterionic form gradually increases with increasing acetonitrile concentration, and in an equally mixed solvent, the zwitterionic and neutral forms are almost isoenergetic, with a difference of only 0.3 kcal mol(-1). The free energy component analysis based on the thermodynamic cycle of the reaction also revealed that the free energy change of the neutral form is insensitive to the change of solvent environment but the zwitterionic form shows drastic changes. In particular, the excess chemical potential, one of the components of the solvation free energy, is dominant and contributes to the stabilization of the zwitterionic form.

  12. Effect of the physicochemical parameters of benzimidazole molecules on their retention by a nonpolar sorbent from an aqueous acetonitrile solution (United States)

    Shafigulin, R. V.; Safonova, I. A.; Bulanova, A. V.


    The effect of the structure of benzimidazoles on their chromatographic retention on octadecyl silica gel from an aqueous acetonitrile eluent was studied. One- and many-parameter correlation equations were obtained by linear regression analysis, and their prognostic potential in determining the retention factors of benzimidazoles under study was analyzed.

  13. Isolation and identification of the acetonitrile-degrading Pseudomonas from the Ab-anbar-e Ganjali Khan in Kerman

    Directory of Open Access Journals (Sweden)

    Narjes Ramezani–pour


    Full Text Available Introduction: Nitriles are toxic and hazardous compounds for all organisms which are produced enormously by human being and cause environment pollution. Biodegradation is the best method for Nitrile elimination in sewage. The aim of this study was isolation and identification of native bacteria Acetonitrile-degrading from the sewage of the city of Kerman. Materials and methods: The enrichment and screening of Acetonitrile degrading bacteria was performed in a specific medium containing 1 % Acetonitrile as sole carbon and nitrogen source. Enzyme activity and ammonium production was determined in growth medium using a modification of the phenol/hypochlorite method. Identification of the isolates was undertaken using microbial - biochemical and molecular tests. The optimization of enzyme production was examined. The amount of nitrile and acid were also determined by gas chromatography. Results: Among three isolated nitrile hydrolyzing producing species (FA3, FA8 and AB19, FA8 isolate showed maximum enzyme productivity. The results of characteristic tests showed that these bacteria belonged to the Pseudomonas sp. Moreover, 16S rRNA sequencing and phylogenetic analyses exhibited that FA11, FA8 and AB19 strains were similar to Pseudomonas Otitidis and Pseudomonas geniculate with 99, 100% homology, respectively. Results of medium optimization of Pseudomonas FA8 strain showed that glucose (10 gL-1 and yeast extract (5 gL-1 in neutral medium strongly supported enzyme production. Gas chromatography results showed that FA8 produced 58% acetic acid at 48 h of incubation. Discussion and conclusion: The results demonstrated that Pseudomonas FA8 isolated bacterium is a suitable candidate for degradation of Acetonitrile. This bacterium could be used for treatment of industrial wastewater and sites that contaminated with Acetonitrile.

  14. A novel liquid/liquid extraction process composed of surfactant and acetonitrile for purification of polygalacturonase enzyme from Durio zibethinus. (United States)

    Amid, Mehrnoush; Manap, Yazid; Azmira, Farhana; Hussin, Muhaini; Sarker, Zaidul Islam


    Polygalacturonase is one of the important enzymes used in various industries such as food, detergent, pharmaceutical, textile, pulp and paper. A novel liquid/liquid extraction process composed of surfactant and acetonitrile was employed for the first time to purify polygalacturonase from Durio zibethinus. The influences of different parameters such as type and concentration of surfactants, concentrations of acetonitrile and composition of surfactant/acetonitrile on partitioning behavior and recovery of polygalacturonase was investigated. Moreover, the effect of pH of system and crude load on purification fold and yield of purified polygalacturonase were studied. The results of the experiment indicated the polygalacturonase was partitioned into surfactant top rich phase with impurities being partitioned into acetonitrile bottom rich phase in the novel method of liquid/liquid process composed of 23% (w/w) Triton X-100 and 19% (w/w) acetonitrile, at 55.6% of TLL (tie line length) crude load of 25% (w/w) at pH 6.0. Recovery and recycling of components also was measured in each successive step of liquid/liquid extraction process. The enzyme was successfully recovered by the method with a high purification factor of 14.3 and yield of 97.3% while phase components were also recovered and recycled above 95%. This study demonstrated that the novel method of liquid/liquid extraction process can be used as an efficient and economical extraction method rather than the traditional methods of extraction for the purification and recovery of the valuable enzyme.

  15. Speciation of La(III) chloride complexes in water and acetonitrile: a density functional study. (United States)

    Bühl, Michael; Sieffert, Nicolas; Partouche, Aurélie; Chaumont, Alain; Wipff, Georges


    Car-Parrinello molecular dynamics (CMPD) simulations and static computations are reported at the BLYP level of density functional theory (DFT) for mixed [LaCl(x)(H(2)O)(y)(MeCN)(z)](3-x) complexes in aqueous and nonaqueous solution (acetonitrile). Both methodologies predict coordination numbers (i.e., x + y + z) that are successively lower than nine as the Cl content increases from x = 0 to 3. While the static DFT method with implicit solvation through a polarizable continuum model overestimates the binding strength of chloride and erroneously predicts [LaCl(2)(H(2)O)(5)](+) as global free-energy minimum, constrained CPMD simulations with explicit solvent and thermodynamic integration reproduce the weak binding of chloride in water reasonably well. Special attention is called to the dipole moments of coordinated water molecules as function of coligands and solvent, evaluated through maximally localized Wannier function centers along the CPMD trajectories. Cooperative polarization of these water ligands by the metal cation and the surrounding solvent is remarkably sensitive to fluctuations of the La-O distances and, to a lesser extent, on the La-water tilt angles. The mean dipole moment of water ligands is rather insensitive to the other coligands, oscillating around 3.2 D, 3.5 D, and 3.3 D in MeCN, water, and [dmim]Cl solution, respectively, the latter being an archetypical ionic liquid.

  16. DFT simulation, quantum chemical electronic structure, spectroscopic and structure-activity investigations of 2-benzothiazole acetonitrile (United States)

    Arjunan, V.; Thillai Govindaraja, S.; Jose, Sujin P.; Mohan, S.


    The Fourier transform infrared and FT-Raman spectra of 2-benzothiazole acetonitrile (BTAN) have been recorded in the range 4000-450 and 4000-100 cm-1 respectively. The conformational analysis of the compound has been carried out to obtain the stable geometry of the compound. The complete vibrational assignment and analysis of the fundamental modes of the compound are carried out using the experimental FTIR and FT-Raman data and quantum chemical studies. The experimental vibrational frequencies are compared with the wavenumbers derived theoretically by B3LYP gradient calculations employing the standard 6-31G**, high level 6-311++G** and cc-pVTZ basis sets. The structural parameters, thermodynamic properties and vibrational frequencies of the normal modes obtained from the B3LYP methods are in good agreement with the experimental data. The 1H (400 MHz; CDCl3) and 13C (100 MHz; CDCl3) nuclear magnetic resonance (NMR) spectra are also recorded. The electronic properties, the energies of the highest occupied and lowest unoccupied molecular orbitals are measured by DFT approach. The kinetic stability of the molecule has been determined from the frontier molecular orbital energy gap. The charges of the atoms and the structure-chemical reactivity relations of the compound are determined by its chemical potential, global hardness, global softness, electronegativity, electrophilicity and local reactivity descriptors by conceptual DFT methods. The non-linear optical properties of the compound have been discussed by measuring the polarisability and hyperpolarisability tensors.

  17. Evaluating the Thermodynamics of Electrocatalytic N 2 Reduction in Acetonitrile

    Energy Technology Data Exchange (ETDEWEB)

    Lindley, Brian M.; Appel, Aaron M.; Krogh-Jespersen, Karsten; Mayer, James M.; Miller, Alexander J. M.


    The synthesis of ammonia by proton-coupled electroreduction of dinitrogen (N2) represents a sustainable alternative to currently practiced hydrogenation methods. Developments in this area require knowledge of the standard reduction potentials that describe the thermodynamics of N2 reduction. The first collection of N2 reduction standard potentials in organic solvent are reported here. The potentials for reduction of N2 to ammonia (NH3), hydrazine (N2H4), and diazene (N2H2) in acetonitrile (MeCN) solution are derived using thermochemical cycles. Ammonia is the thermodynamically favored product, with a 0.43 V difference between NH3 and N2H4 and a 1.26 V difference between NH3 and N2H2. The thermodynamics for reduction of N2 to the protonated products ammonium (NH4+) and hydrazinium (N2H5+) under strongly acidic conditions are also presented. Comparison with previously determined values for the H+/H2 potential in MeCN reveals a 63 mV thermodynamic preference for N2 reduction to NH3 over H2 production. Combined with knowledge of the kinetics of electrode-catalyzed H2 evolution, a wide working region is identified to guide future electrocatalytic studies.

  18. Early-Lanthanide(III) Acetonitrile-Solvento Adducts with Iodide and Noncoordinating Anions. (United States)

    Brown, Jessie L; Davis, Benjamin L; Scott, Brian L; Gaunt, Andrew J


    Dissolution of LnI3 (Ln = La, Ce) in acetonitrile (MeCN) results in the highly soluble solvates LnI3(MeCN)5 [Ln = La (1), Ce (2)] in good yield. The ionic complex [La(MeCN)9][LaI6] (4), containing a rare homoleptic La(3+) cation and anion, was also isolated as a minor product. Extending this chemistry to NdI3 results in the consistent formation of the complex ionic structure [Nd(MeCN)9]2[NdI5(MeCN)][NdI6][I] (3), which contains an unprecedented pentaiodide lanthanoid anion. Also described is the synthesis, isolation, and structural characterization of several homoleptic early-lanthanide MeCN solvates with noncoordinating anions, namely, [Ln(MeCN)9][AlCl4]3 [Ln = La (5), Ce (6), Nd (7)]. Notably, complex 6 is the first homoleptic cerium MeCN solvate reported to date. All reported complexes were structurally characterized by X-ray crystallography, as well as by IR spectroscopy and CHN elemental analysis. Complexes 1-3 were also characterized by thermogravimetric analysis coupled with mass spectrometry to further elucidate their bulk composition in the solid-state.

  19. Electrical conductivity and dielectric relaxation of 2-(antipyrin-4-ylhydrazono)-2-(4-nitrophenyl)acetonitrile

    Energy Technology Data Exchange (ETDEWEB)

    El-Menyawy, E.M., E-mail: [Solid State Electronics Laboratory, Solid State Physics Department, Physics Division, National Research Center, Dokki, Cairo 12311 (Egypt); Zedan, I.T. [Basic Science Department, High Institute of Engineering and Technology, El-Arish, North Sinai (Egypt); Nawar, H.H. [Department of Chemistry, Faculty of Education, Al Jabal Al Gharbi University (Libya)


    The electrical and dielectric properties of the synthesized 2-(antipyrin-4-ylhydrazono)-2-(4-nitrophenyl)acetonitrile (AHNA) have been studied. The direct and alternating current (DC and AC) conductivities and complex dielectric constant were investigated in temperature range 303–403 K. The AC conductivity and dielectric properties of AHNA were investigated over frequency range 100 Hz–5 MHz. From DC and AC measurements, electrical conduction is found to be a thermally activated process. The frequency-dependent AC conductivity obeys Jonscher's universal power law in which the frequency exponent decreases with increasing temperature. The correlated barrier hopping (CBH) is the predominant model for describing the charge carrier transport in which the electrical parameters are evaluated. The activation energy is found to decrease with increasing frequency. The behaviors of dielectric and dielectric loss are discussed in terms of a polarization mechanism. The dielectric loss shows frequency power law from which the maximum barrier height is determined as 0.19 eV in terms of the Guintini model.

  20. Structure and dynamics of 1-N-alkyl-3-N-methylimidazolium tetrafluoroborate + acetonitrile mixtures. (United States)

    Stoppa, Alexander; Hunger, Johannes; Hefter, Glenn; Buchner, Richard


    A detailed investigation of the binary mixtures of the ionic liquids (ILs) 1-N-R-3-N-methylimidazolium tetrafluoroborate (R = ethyl, n-butyl, n-hexyl) with the important molecular solvent acetonitrile (AN) over the entire composition range has been made at 25 °C using broadband dielectric spectroscopy. All spectra showed two modes: a Cole-Cole (CC) mode centered at ~2 GHz and a Debye mode centered at ~50 GHz. However, detailed analysis indicated both relaxations were composites. The Debye mode arises from the rotational diffusion of free AN molecules with contributions from ultrafast vibrations and librations of the ILs. The CC mode corresponds to the jump rotation of the imidazolium cations and the hindered rotational diffusion of "slow" AN molecules solvating them. At very low IL concentrations 1:1 contact ion pairs are dominant. Overall, these IL + AN mixtures can be divided into two broad regions: at IL mole fraction (x(IL)) ≲ 0.2 the IL behaves as a rather weakly associated conventional electrolyte while at x(IL) ≳ 0.2 it takes on its IL characteristics, "lubricated" by the AN.

  1. Substituent effects in the 13C NMR chemical shifts of alpha-mono-substituted acetonitriles. (United States)

    Reis, Adriana K C A; Rittner, Roberto


    13C chemical shifts empirical calculations, through a very simple additivity relationship, for the alpha-methylene carbon of some alpha-mono-substituted acetonitriles, Y-CH(2)-CN (Y=H, F, Cl, Br, I, OMe, OEt, SMe, SEt, NMe(2), NEt(2), Me and Et), lead to similar, or even better, results in comparison to the reported values obtained through Quantum Mechanics methods. The observed deviations, for some substituents, are very similar for both approaches. This divergence between experimental and calculated, either empirically or theoretically, values are smaller than for the corresponding acetones, amides, acetic acids and methyl esters, which had been named non-additivity effects (or intramolecular interaction chemical shifts, ICS) and attributed to some orbital interactions. Here, these orbital interactions do not seem to be the main reason for the non-additivity effects in the empirical calculations, which must be due solely to the magnetic anisotropy of the heavy atom present in the substituent. These deviations, which were also observed in the theoretical calculations, were attributed in that case to the non-inclusion of relativistic effects and spin-orbit coupling in the Hamiltonian. Some divergence is also observed for the cyano carbon chemical shifts, probably due to the same reasons.

  2. Structures of the ozonolysis products and ozonolysis pathway of aflatoxin B1 in acetonitrile solution. (United States)

    Diao, Enjie; Shan, Changpo; Hou, Hanxue; Wang, Shanshan; Li, Minghua; Dong, Haizhou


    The ozonolysis of aflatoxin B(1) (400 μg/mL) in acetonitrile solution was conducted with an ozone concentration of 6.28 mg/L at the flow rate of 60 mL/min for different times. The results showed that ozone was an effective detoxification agent because of its powerful oxidative role. Thin-layer chromatography and liquid chromatography-quadrupole time-of-flight mass spectra were applied to confirm and identify the ozonolysis products of aflatoxin B(1). A total of 13 products were identified, and 6 of them were main products. The structural identification of these products provided effective information for understanding the ozonolysis pathway of aflatoxin B(1). Two ozonolysis pathways were proposed on the basis of the accurate mass and molecular formulas of these product ions. Nine ozonolysis products came from the first oxidative pathway based on the Criegee mechanism, and the other four products were produced from the second pathway based on the oxidative and electrophilic reactions of ozone. According to the toxicity mechanism of aflatoxin B(1) to animals, the toxicity of aflatoxin B(1) was significantly reduced because of the disappearance of the double bond on the terminal furan ring or the lactone moiety on the benzene ring.

  3. Polymerization of Acetonitrile via a Hydrogen Transfer Reaction from CH3 to CN under Extreme Conditions. (United States)

    Zheng, Haiyan; Li, Kuo; Cody, George D; Tulk, Christopher A; Dong, Xiao; Gao, Guoying; Molaison, Jamie J; Liu, Zhenxian; Feygenson, Mikhail; Yang, Wenge; Ivanov, Ilia N; Basile, Leonardo; Idrobo, Juan-Carlos; Guthrie, Malcolm; Mao, Ho-Kwang


    Acetonitrile (CH3 CN) is the simplest and one of the most stable nitriles. Reactions usually occur on the C≡N triple bond, while the C-H bond is very inert and can only be activated by a very strong base or a metal catalyst. It is demonstrated that C-H bonds can be activated by the cyano group under high pressure, but at room temperature. The hydrogen atom transfers from the CH3 to CN along the CH⋅⋅⋅N hydrogen bond, which produces an amino group and initiates polymerization to form a dimer, 1D chain, and 2D nanoribbon with mixed sp(2) and sp(3) bonded carbon. Finally, it transforms into a graphitic polymer by eliminating ammonia. This study shows that applying pressure can induce a distinctive reaction which is guided by the structure of the molecular crystal. It highlights the fact that very inert C-H can be activated by high pressure, even at room temperature and without a catalyst.

  4. The impact of highly correlated potential energy surfaces on the anharmonically corrected IR spectrum of acetonitrile (United States)

    Lutz, Oliver M. D.; Rode, Bernd M.; Bonn, Günther K.; Huck, Christian W.


    This paper discusses the quality and feasibility of highly correlated ab initio techniques in a vibrational self-consistent field (VSCF) approach using acetonitrile as a model system. The topical renormalized coupled-cluster technique exploiting the similarity-transformed Hamiltonian's left eigenstates (i.e. CR-CC(2,3)) is investigated alongside the well-known Hartree-Fock (HF), Møller-Plesset second-order perturbation theory (MP2) and coupled cluster (CCSD(T)) methods. The inclusion of mode triple interactions is discussed and it is found that the use of an effective core potential (ECP) serves as a viable compromise during the highly demanding task of computing such contributions, thus enabling a grid-based evaluation of three mode interaction terms with coupled cluster techniques also for larger molecules. In this context, a previously proposed reduced coupling scheme [1] is investigated, confirming the applicability of this technique to a system exhibiting a rather complex electronic structure. A combination of Ahlrichs' triple-ζ valence polarized (TZVP) basis set with Dunning's set of core-valence correlation functions is found to deliver results in good agreement with experiment while being computationally very feasible. Since CH3CN exhibits four degenerate vibrational degrees of freedom, it serves as an ideal model system for critically assessing the qualities of the degenerate second-order perturbation theory corrected (DPT2) VSCF technique. Besides fundamental vibrations, a thorough investigation of overtone transitions and combination bands is conducted by means of comparing the results to both available and newly recorded experimental data.

  5. Spectroscopic investigation of europium benzoate in acetonitrile: Luminescence enhancement and complexation studies

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Satendra; Maji, S. [Materials Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Joseph, M. [Fuel Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Sankaran, K., E-mail: [Materials Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)


    Luminescence from Eu{sup 3+} complexed with benzoic acid (BA) has been studied using acetonitrile (MeCN) as solvent. More than two orders luminescence enhancement is found as compared to Eu{sup 3+}–BA complex in aqueous medium. The lifetime of Eu{sup 3+} in this complex is 900 μs which is much higher as compared to 118 μs in aqueous medium, suggesting the luminescence enhancement is a result of reduction in non-radiative decay channels in MeCN medium. Luminescence spectroscopy along with UV–vis spectroscopy is used to study the complexation behavior of Eu{sup 3+}–BA in this medium. In contrary to aqueous medium where Eu{sup 3+}–BA forms ML and ML{sub 2} type species, spectroscopic data reveal formation of only ML{sub 3} complex with composition Eu(BA){sub 3}(MeCN){sub 6} in MeCN medium. Absorbance, luminescence lifetimes and the ratio of areas of 615–592 nm peaks are used in HypSpec computation program to determine the log β for the ML{sub 3} complex. - Highlights: • Luminescence and complexation of Eu{sup 3+}–BA have been studied in MeCN. • The luminescence intensity of Eu{sup 3+}–BA is 320 times more in MeCN compared to aqueous medium. • Luminescence enhancement is a result of sensitization and reduction in non-radiative decay channels in MeCN. • Eu{sup 3+} forms only ML{sub 3} type complex with BA in MeCN contrary to aqueous medium where it forms ML and ML{sub 2} type species.

  6. Freeze-out extraction of monocarboxylic acids from water into acetonitrile under the action of centrifugal forces (United States)

    Bekhterev, V. N.


    It is established that the efficiency of the freezing-out extraction of monocarboxylic acids C3-C;8 and sorbic acid from water into acetonitrile increases under the action of centrifugal forces. The linear growth of the partition coefficient in the homologous series of C2-C8 acids with an increase in molecule length, and the difference between the efficiency of extracting sorbic and hexanoic acid, are discussed using a theoretical model proposed earlier and based on the adsorption-desorption equilibrium of the partition of dissolved organic compounds between the resulting surface of ice and the liquid phase of the extract. The advantages of the proposed technique with respect to the degree of concentration over the method of low-temperature liquid-liquid extraction are explained in light of the phase diagram for the water-acetonitrile mixture.

  7. Photochemical oxidation of thiophene by O2 in an oil/acetonitrile two-phase extraction system. (United States)

    Li, Fa-Tang; Zhao, Di-Shun; Li, Hong-Xia; Liu, Rui-Hong


    Photochemical oxidation of thiophene in an n-octane/acetonitrile extraction system using O(2) as oxidant was studied. Results obtained here can be used as a reference for desulfurization of gasoline, because thiophene is one of the main components containing sulfur in fluid catalytic cracking gasoline. A 500-W high-pressure mercury lamp was used as a light source for irradiation, and air was introduced by a gas pump to supply O(2). Thiophene dissolved in nopolar n-octane solvent was photodecomposed and removed into the polar acetonitrile phase. The desulfurization rate of thiophene in n-octane was 65.2% under photoirradiation for 5 h under the conditions of air flow at 150 mL min(-1), and V(n-octane):V(acetonitrile) = 1:1. This can be improved to 96.5% by adding 0.15 g Na-ZSM-5 zeolite into the 100-mL reaction system, which is the absorbent for O(2) and thiophene. Under such conditions, the photooxidation kinetics of thiophene with O(2) and Na-ZSM-5 zeolite is first-order with an apparent rate constant of 0.6297 h(-1) and half-time of 1.10 h. The sulfur content can be reduced from 800 microL L(-1) to 28 microL L(-1).

  8. Adsorption characteristics of acetone, chloroform and acetonitrile on sludge-derived adsorbent, commercial granular activated carbon and activated carbon fibers. (United States)

    Tsai, Jiun-Horng; Chiang, Hsiu-Mei; Huang, Guan-Yinag; Chiang, Hung-Lung


    The adsorption characteristics of chloroform, acetone, and acetonitrile on commercial activated carbon (C1), two types of activated carbon fibers (F1 and F2), and sludge adsorbent (S1) was investigated. The chloroform influent concentration ranged from 90 to 7800 ppm and the acetone concentration from 80 to 6900 ppm; the sequence of the adsorption capacity of chloroform and acetone on adsorbents was F2>F1 approximately C1 approximately S1. The adsorption capacity of acetonitrile ranged from 4 to 100 mg/g, corresponding to the influent range from 43 to 2700 ppm for C1, S1, and F1. The acetonitrile adsorption capacity of F2 was approximately 20% higher than that of the other adsorbents at temperaturescarbon fibers is higher than that of the other adsorbents due to their smaller fiber diameter and higher surface area. The micropore diffusion coefficient of VOC on activated carbon and sludge adsorbent was approximately 10(-4) cm2 s(-1). The diffusion coefficient of VOC on carbon fibers ranged from 10(-8) to 10(-7) cm2 s(-1). The small carbon fiber pore size corresponds to a smaller diffusion coefficient.

  9. Experimental FTIR and theoretical studies of gallic acid-acetonitrile clusters (United States)

    Hirun, Namon; Dokmaisrijan, Supaporn; Tantishaiyakul, Vimon


    Gallic acid (3,4,5-trihydroxybenzoic acid, GA) has many possible conformers depending on the orientations of its three OH and COOH groups. The biological activity of polyphenolic compounds has been demonstrated to depend on their conformational characteristics. Therefore, experimental FTIR and theoretical studies of the GA-solvent clusters were performed to investigate the possible most favored conformation of GA. Acetonitrile (ACN) was selected as the solvent since its spectrum did not interfere with the OH stretching bands of GA. Also of importance was that these OH groups, in addition to the carboxyl group, of the GA are the most likely groups to interact with receptors. The solution of GA in the ACN solution was measured and the complex OH bands were deconvoluted to four component bands. These component bands corresponded to the three OH bands on the benzene ring and a broad band which is a combination band of mainly the OH of the COOH group and the inter- and intramolecular H-bonds from the OH groups on the ring. The conformations, relative stabilities and vibrational analysis of the GA monomers and the GA-ACN clusters were investigated using the B3LYP/6-311++G(2d,2p) method. Conformational analysis of the GA monomer yielded four most possible conformers, GA-I, GA-II, GA-III and GA-IV. These conformers were subsequently used for the study of the GA:ACN clusters at the 1:1, 1:2 and 1:4 mole ratios. The IR spectra of the most stable structures of these clusters were simulated and the vibrational wavenumbers of the OH and C dbnd O groups were compared with those from the experiment. The FTIR component bands were comparable to the computed OH bands of the GA-I-(ACN) 2, GA-IV-(ACN) 2 and GA-I-(ACN) 4 clusters. Furthermore, the C dbnd O stretching bands and the bands in the regions of 1800-1000 cm -1 obtained by computing and the experiment were similar for these clusters. Thus, GA-I and GA-IV are the most preferable conformations of GA in ACN and perhaps in the

  10. Pyrazolylamidino ligands from coupling of acetonitrile and pyrazoles: a systematic study. (United States)

    Gómez-Iglesias, Patricia; Arroyo, Marta; Bajo, Sonia; Strohmann, Carsten; Miguel, Daniel; Villafañe, Fernando


    Mixed pyrazole-acetonitrile complexes, both neutral fac-[ReBr(CO)3(NCMe)(pz*H)] (pz*H = pzH, pyrazole; dmpzH, 3,5-dimethylpyrazole; or indzH, indazole) and cationic fac-[Re(CO)3(NCMe)(pz*H)2]A (A = BF4, ClO4, or OTf), are described. Their role as the only starting products to obtain final pyrazolylamidino complexes fac-[ReBr(CO)3(NH═C(Me)pz*-κ(2)N,N)] and fac-[Re(CO)3(pz*H)(NH═C(Me)pz*-κ(2)N,N)]A, respectively, is examined. Other products involved in the processes, such as fac-[ReBr(CO)3(pz*H)2], fac-[Re(CO)3(NCMe)(NH═C(Me)pz*-κ(2)N,N)]A, and fac-[Re(CO)3(pz*H)2(OTf)] are also described. Warming CD3CN solutions of fac-[Re(CO)3(NCMe)(pz*H)2]A at 40 °C gives cleanly the pyrazolylamidino complexes [Re(CO)3(pz*H)(NH═C(Me)pz*-κ(2)N,N)]A as the only products, pointing to an intramolecular process. This is confirmed by carrying out reactions in the presence of one equivalent of a pyrazole different from that coordinated, which affords complexes where the pyrazolylamidino ligand contains only the pyrazole previously coordinated. When the reactions lead to an equilibrium mixture of the final and starting products, the reverse reaction gives the same equilibrium mixture, which indicates that the coupling reaction of pyrazoles and nitriles to obtain pyrazolylamidino ligands is a reversible intramolecular process. A systematic study of the possible factors which may affect the reaction gives the following results: (a) the yields of the direct reactions are higher for lower temperatures; (b) the tendency of the pyrazoles to give pyrazolylamidino complexes follows the sequence indzH > pzH > dmpzH; and (c) the reaction rates do not depend on the nature of the anion even when a large excess is added. The presence of a small amount of aqueous solution of NaOH catalyzes the reaction. Thus, addition of 0.5-1% of NaOH (aq) to solutions of fac-[ReBr(CO)3(NCMe)(pz*H)] (in CD3CN) or fac-[Re(CO)3(NCMe)(pz*H)2]A (in CD3CN, CD3NO2 or (CD3)2CO) allowed the syntheses of the

  11. 含钠碱选择性催化乙腈环三聚反应%Selective Cyclotrimerization of Acetonitrile Catalyzed by Sodium-Based Alkali

    Institute of Scientific and Technical Information of China (English)

    陶晓春; 陶辉; 刘涛平; 钱延龙


    4-amino-pyrimidine not only has important biological activity[1], but also is the intermediate for some medicines. It can be prepared by cyclotrimerization of nitriles. Meyer[2] found that acetonitrile could be cyclotrimerized to 4-amino-2,6-dimethyl-pyrimidine in the presence of sodium. Excess sodium methoxide or potassium methoxide reacts with acetonitrile to give this product in a sealed equipment at 140 ℃ for 5 h with 70%~80% yield[3,4].

  12. catena-Poly[[[bis(thiourea-κScopper(I]-μ-thiourea-κ2S:S] iodide acetonitrile hemisolvate

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    Da-Cheng Li


    Full Text Available The title complex, {[Cu(CH4N2S3]I·0.5CH3CN}n, was formed by the reaction of CuI and thiourea in acetonitrile. There are two independent CuI ions in the asymmetric unit which are coordinated by two terminal and two bridging thiourea ligands to form a one-dimensional helical chain structure progagating in the a-axis direction. Each CuI ion is in a distorted tetrahedral coordination environment. The crystal structure is stabilized by weak N—H...S and N—H...I hydrogen bonds.

  13. Bis(μ2-diphenylphosphinamide-κ2O:Obis[bis(diphenylphosphinamide-κOlithium] dichloride acetonitrile disolvate

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    Ai-Hong Li


    Full Text Available The asymmetric unit of the title compound, [Li2(C12H12NOP6]Cl2·2CH3CN, contains one-half of the centrosymmetric dication, one chloride anion and one acetonitrile solvent molecule. Each Li atom is coordinated by four O atoms [Li—O 1.891 (3 and 2.025 (3 Å] from the four diphenylphosphinamide ligands in a distorted tetrahedral geometry. In the crystal, weak N—H...Cl hydrogen bonds link the anions and dications into columns extending along [100].

  14. Stacking and Analysis of Melamine in Milk Products with Acetonitrile-Salt Stacking Technique in Capillary Electrophoresis (United States)

    Wei, Chong; Hou, Zhanwu; Wang, Zilong; Yuan, Jiaqiang; Yu, Jiang; Zhao, Yongxi; Tang, Yuhai; Gao, Meili


    Melamine was measured in real milk products with capillary electrophoresis (CE) based on acetonitrile-salt stacking (ASS) method. Real milk samples were deproteinized with acetonitrile at a final concentration of 60% (v/v) and then injected hydrodynamically at 50 mBar for 40.0 s. The optimized buffer contains 80.0 mmol/L pH 2.8 phosphates. Melamine could be detected within 20.0 min at +10 kV with a low limit of detection (LOD) of 0.03 μmol/L. Satisfactory reproducibility (inter- and intraday RSD% both for migration time and peak area was lower than 5.0%) and a wide linearity range of 0.05 μmol/L ~ 10.0 μmol/L were achieved. The proposed method was suitable for routine assay of MEL in real milk samples that was subjected to a simple treatment step. PMID:25197612

  15. Crystal structure of catena-poly[[[trans-bis(acetonitrile-κNdiaquacobalt(II]-μ-pyrazine-κ2N:N′] dinitrate

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    Chen Liu


    Full Text Available The central structural motif of the title coordination polymer, [Co(NO32(C4H4N2(CH3CN2(H2O2]n, is a chain composed of CoII ions linked by bis-monodentate bridging pyrazine ligands through their N atoms. The CoII ion is located on an inversion center and is additionally coordinated by two O atoms of water molecules and two N atoms of acetonitrile molecules. The resultant N4O2 coordination sphere is distorted octahedral. The linear cationic chains extend parallel to the a axis and are aligned into layers parallel to the ac plane. Nitrate anions are situated in the space between the CoII chains and form O—H...O hydrogen bonds with the coordinating water molecules, leading to a three-dimensional network structure. Weak C—H...O hydrogen bonds are also present between pyrazine or acetonitrile molecules and the nitrate anions.

  16. Stacking and Analysis of Melamine in Milk Products with Acetonitrile-Salt Stacking Technique in Capillary Electrophoresis

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    Yu Kong


    Full Text Available Melamine was measured in real milk products with capillary electrophoresis (CE based on acetonitrile-salt stacking (ASS method. Real milk samples were deproteinized with acetonitrile at a final concentration of 60% (v/v and then injected hydrodynamically at 50 mBar for 40.0 s. The optimized buffer contains 80.0 mmol/L pH 2.8 phosphates. Melamine could be detected within 20.0 min at +10 kV with a low limit of detection (LOD of 0.03 μmol/L. Satisfactory reproducibility (inter- and intraday RSD% both for migration time and peak area was lower than 5.0% and a wide linearity range of 0.05 μmol/L ~ 10.0 μmol/L were achieved. The proposed method was suitable for routine assay of MEL in real milk samples that was subjected to a simple treatment step.

  17. Hydrogen bonding interactions in ethanol and acetonitrile binary system: A near and mid-infrared spectroscopic study (United States)

    Zhou, Yu; Zheng, Yan-Zhen; Sun, Hai-Yuan; Deng, Geng; Yu, Zhi-Wu


    The hydrogen bond interactions in C2H5OHsbnd CH3CN binary system have been studied in detail by near-infrared spectroscopy (NIR), attenuated total reflection (ATR) mid-infrared spectroscopy (mid-IR), and density functional theory (DFT) calculations. The collected spectra were analyzed with excess spectroscopy and two-dimensional correlation spectroscopy (2D-COS) including moving-window 2D-COS. The main conclusions are: (1) A number of species, namely multimer, trimmer, and dimer of C2H5OH, and C2H5OH⋯CD3CN hydrogen bonding complex, have been identified in the binary system C2H5OHsbnd CH3CN experimentally. The linear relationship between the observed and calculated wavenumbers of the concerned species assisted us in doing the assignments. (2) Adding acetonitrile, the hydrogen bonds in C2H5OH are weakened and C2H5OH multimers dissociate. Meanwhile, C2H5OH dimers and C2H5OH⋯CD3CN hydrogen bonding complex form, and the former also transform to the latter. The dissociation of C2H5OH multimers slows down gradually during the dilution process and at the mole fraction 0.7 of acetonitrile, all the C2H5OH multimers have dissociated.

  18. On-column nitrosation of amines observed in liquid chromatography impurity separations employing ammonium hydroxide and acetonitrile as mobile phase. (United States)

    Myers, David P; Hetrick, Evan M; Liang, Zhongming; Hadden, Chad E; Bandy, Steven; Kemp, Craig A; Harris, Thomas M; Baertschi, Steven W


    The availability of high performance liquid chromatography (HPLC) columns capable of operation at pH values up to 12 has allowed a greater selectivity space to be explored for method development in pharmaceutical analysis. Ammonium hydroxide is of particular value in the mobile phase because it is compatible with direct interfacing to electrospray mass spectrometers. This paper reports an unexpected N-nitrosation reaction that occurs with analytes containing primary and secondary amines when ammonium hydroxide is used to achieve the high pH and acetonitrile is used as the organic modifier. The nitrosation reaction has generality. It has been observed on multiple columns from different vendors and with multiple amine-containing analytes. Ammonia was established to be the source of the nitroso nitrogen. The stainless steel column frit and metal ablated from the frit have been shown to be the sites of the reactions. The process is initiated by removal of the chromium oxide protective film from the stainless steel by acetonitrile. It is hypothesized that the highly active, freshly exposed metals catalyze room temperature oxidation of ammonia to NO but that the actual nitrosating agent is likely N(2)O(3).

  19. Studies on the Hydrogenation of Acetonitrile over Fresh Mo2C/γ-Al2O3 Catalyst by In-situ IR Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Zhang Jing; Wu Weicheng; Liu Chuang; Ding Xiaoguang; Chu Gang; Zhang Jianguo


    The adsorption of acetonitrile, the co-adsorption of acetonitrile with CO, and hydrogenation of acetonitrile on fresh Mo2C/γ-Al2O3 catalyst were studied by in situ IR spectroscopy. It was found out that CH3CN exhibited strong interac-tion with the fresh Mo2C/γ-Al2O3 catalyst and was adsorbed mainly on Moδ+sites of fresh Mo2C/γ-Al2O3 catalyst. Moreover, CH3CN could affect the shifting of IR spectra for CO adsorption towards a lower wave number. The IR spectroscopic study on acetonitrile hydrogenation showed that CH3CN could be easily hydrogenated in the presence of H2 on the Mo2C/γ-Al2O3 catalyst. Furthermore, it was observed that CH3CN could be selectively hydrogenated to imines on fresh Mo2C/γ-Al2O3 catalyst. Additionally, the active sites of fresh Mo2C/γ-Al2O3 catalyst might be covered with coke during the hydrogenation reaction of acetonitrile. The treatment of catalyst with hydrogen at 673 K could not completely remove coke deposits on the surface of the Mo2C/γ-Al2O3 catalyst.

  20. Distribution of pesticides in n-hexane/water and n-hexane/acetonitrile systems and estimation of possibilities of their extraction isolation and preconcentration from various matrices. (United States)

    Zayats, M F; Leschev, S M; Petrashkevich, N V; Zayats, M A; Kadenczki, L; Szitás, R; Szemán Dobrik, H; Keresztény, N


    Distribution of 150 most widely used pesticides of different chemical classes (amides, anilinopirimidines, aromatics, benzenesulfonates, carbamates, dicarboximides, organophosphorus compounds, phenyl esters, phenylureas, pyrazoles, pyrethroids, pyrimidines, strobilurins, sulfamides, triazines, triazoles, etc.) in n-hexane/water and n-hexane/acetonitrile systems was investigated at 25°C. Distribution constants of pesticides (P) have been calculated as ratio of pesticide concentration in n-hexane to its concentration in water or acetonitrile phase. HPLC and GC methods were used for pesticides determination in phases. It was found that the overwhelming majority of pesticides are hydrophobic, i.e. in n-hexane/water system LgP≫0, and the difference in LgP values can reach 9.1 units. Replacement of water for acetonitrile leads to dramatic fall of LgP values reaching 9.5 units. The majority of LgP values in this case are negative and their differences is strongly leveled in comparison with a hexane/water system. Thus, maximal difference in pesticides LgP values for n-hexane/acetonitrile system is 3.2 units. It is shown that n-hexane can be used for selective and efficient extraction and preconcentration of pesticides from water matrices. On the other hand, acetonitrile is effective for the isolation and preconcentration of pesticides from hydrocarbon and vegetable oil matrices. The distribution constants described in the paper may be effectively used for the estimation of possibilities of extraction isolation, preconcentration and separation of pesticides.

  1. A Study of Acid-Base Equilibria in Acetonitrile Systems of 2-Halo(Cl,Br,I-4-nitropicoline(3,5,6 N-oxides

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    Lech Chmurzynski


    Full Text Available An attempt has been made to determine potentiometrically (1 acid dissociation constants of cations obtained by protonation of nine trisubstituted pyridine N-oxides, namely 2-halo(Cl, Br and I-4-nitropicoline N-oxides with the methyl group at positions 3, 5, and 6, as well as (2 the cationic homoconjugation constants of these cationic acids with conjugated N-oxides in acetonitrile. On the basis of the substitution effect, variations of the acid dissociation constants of the trisubstituted pyridine N-oxide cations are discussed. The determined pKa values of the protonated 2-halo-4-nitropicoline N-oxides are compared with the previously determined equilibrium constants of the cationic acids conjugated with the mono- and disubstituted pyridine N-oxides in acetonitrile. Further, based on the pKa values of the protonated 2-halo-4-nitropicoline N-oxides in acetonitrile, supplemented with correlations between pKa’s of the protonated mono- and disubstituted pyridine N-oxides in acetonitrile and water, the pKa's of the acids conjugated with the trisubstituted N-oxides studied in aqueous solutions have been estimated. Moreover, it has been concluded that the cationic homoconjugation constants cannot be determined by potentiometric titration in acetonitrile solutions of the 2-halo-4-nitropicoline N-oxide systems.

  2. Solvation of fluoro-acetonitrile in water by 2D-IR spectroscopy: A combined experimental-computational study

    Energy Technology Data Exchange (ETDEWEB)

    Cazade, Pierre-André; Das, Akshaya K. [Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel (Switzerland); Tran, Halina; Kläsi, Felix; Hamm, Peter [Department of Chemistry, University of Zurich, Winterthurerstr. 190, 8057 Zurich (Switzerland); Bereau, Tristan [Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz (Germany); Meuwly, Markus, E-mail: [Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel (Switzerland); Department of Chemistry, Brown University, Providence, Rhode Island 02912 (United States)


    The solvent dynamics around fluorinated acetonitrile is characterized by 2-dimensional infrared spectroscopy and atomistic simulations. The lineshape of the linear infrared spectrum is better captured by semiempirical (density functional tight binding) mixed quantum mechanical/molecular mechanics simulations, whereas force field simulations with multipolar interactions yield lineshapes that are significantly too narrow. For the solvent dynamics, a relatively slow time scale of 2 ps is found from the experiments and supported by the mixed quantum mechanical/molecular mechanics simulations. With multipolar force fields fitted to the available thermodynamical data, the time scale is considerably faster—on the 0.5 ps time scale. The simulations provide evidence for a well established CF–HOH hydrogen bond (population of 25%) which is found from the radial distribution function g(r) from both, force field and quantum mechanics/molecular mechanics simulations.

  3. Salting-out effect of ionic liquids on isobaric vapor-liquid equilibrium of acetonitrile-water system☆

    Institute of Scientific and Technical Information of China (English)

    Jing Fang; Rui Zhao; Hui Wang; Chunli Li; Jing Liu


    This paper presents the vapor–liquid equilibrium (VLE) data of acetonitrile–water system containing ionic liquids (ILs) at atmospheric pressure (101.3 kPa). Since ionic liquids dissociate into anions and cations, the VLE data for the acetonitrile+water+ILs systems are correlated by salt effect models, Furter model and improved Furter model. The overall average relative deviation of Furter model and improved Furter model is 5.43%and 4.68%, respectively. Thus the salt effect models are applicable for the correlation of IL containing systems. The salting-out effect theory can be used to explain the change of relative volatility of acetonitrile–water system.

  4. A pooled analysis of the efficacy of monepantel, an amino-acetonitrile derivative against gastrointestinal nematodes of sheep. (United States)

    Hosking, Barry C; Kaminsky, Ronald; Sager, Heinz; Rolfe, Peter F; Seewald, Wolfgang


    Monepantel is the first compound from the amino-acetonitrile derivative class of anthelmintics to be developed for the control of gastrointestinal nematodes of sheep. An analysis of pooled data from a series of controlled studies is reported providing a single point of efficacy (+/- 95% confidence interval) for each gastrointestinal nematode tested at the fourth larval and/or adult stages. For most nematode species, the pooled efficacy was greater than 99%, and for the remaining few species, efficacy was greater than 90%. These data are well supported by field studies conducted across five countries, where the pooled efficacy (on the basis of fecal worm egg count reduction) was in most cases, greater than 99% (depending on the calculation used). Monepantel is highly effective when administered to sheep at 2.5 mg/kg, and its introduction as a new anthelmintic for sheep is timely, given the problems with anthelmintic resistance that the world's sheep farmers are now experiencing.

  5. Aquachloridobis(2-ethoxy-6-formylphenolato-κ2O1,O6chromium(III acetonitrile hemisolvate

    Directory of Open Access Journals (Sweden)

    Reza Kia


    Full Text Available In the mononuclear complex molecule of the title compound, [Cr(C9H9O32Cl(H2O]·0.5CH3CN, the CrIII atom displays an elongated octahedral coordination geometry. The dihedral angle between the benzene rings is 12.27 (11°. Adjacent complex molecules are linked into dimers by O—H...O hydrogen bonds, generating rings of R12(6 and R12(5 graph-set motifs, and by aromatic π–π stacking interactions, with a centroid–centroid distance of 3.812 (2 Å. The crystal packing is further stabilized by intermolecular C—H...N hydrogen bonds. The C and N atoms of the acetonitrile solvent molecule are located on a crystallographic twofold axis.

  6. Comparison of methanol and acetonitrile as solvents for the separation of sertindole and its major metabolites by capillary zone electrophoresis. (United States)

    Subirats, Xavier; Reinstadler, Sigrun; Porras, Simo P; Raggi, Maria Augusta; Kenndler, Ernst


    Sertindole (1-[2-[4-[5-chloro-1-(4-fluorophenyl)-1H-indol-3-yl]-1-piperidinyl]ethyl]-2-imidazolidinone), an atypical antipsychotic drug, was separated by capillary electrophoresis from its two main metabolites norsertindole and dehydrosertindole. The low solubility of the analytes in water (octanol-water partition coefficient is about 10(5)) is overcome by the use of methanol (MeOH) and acetonitrile (ACN) as solvents for the background electrolyte (BGE). Mobilities were measured in BGEs with defined pH in a broad range. It was found that in MeOH the mobility of the analytes is mainly governed by acid-base equilibria, whereas in ACN other reactions like ion pairing and homo-conjugation play a pronounced role and lead to a complex pattern of the mobility as function of the pH. However, separation can be obtained in less than 10 min in both solvent systems.

  7. Bis(acetonitrile-κN(1,10-phenanthroline-κ2N,N′platinum(II bis(perchlorate

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    Kwang Ha


    Full Text Available The asymmetric unit of the title compound, [Pt(CH3CN2(C12H8N2](ClO42, contains one half of a cationic PtII complex and pair of half perchlorate anions, one of which is disordered over two sites in a 0.53 (3:0.47 (3 ratio. The complex and anions are disposed about a crystallographic mirror plane parallel to the ac plane passing through the Pt and Cl atoms. In the complex, the PtII ion lies in a distorted square-planar environment defined by four N atoms of the chelating 1,10-phenanthroline ligand and two distinct acetonitrile molecules. The component ions interact by means of intermolecular C—H...O hydrogen bonds.

  8. 2-{[2-Methyl-3-(2-methylphenyl-4-oxo-3,4-dihydroquinazolin-8-yl]oxy}acetonitrile

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    Adel S. El-Azab


    Full Text Available In the title compound, C18H15N3O2, the fused ring system is almost planar [the dihedral angle between the six-membered rings is 1.81 (6°]. The 2-tolyl ring is approximately orthogonal to this plane [dihedral angle = 83.03 (7°] as is the acetonitrile group [C—O—C—C torsion angle = 79.24 (14°] which is also syn to the methyl substituent of the tolyl group. In the crystal, supramolecular layers are formed in the bc plane mediated by C—H...O, C—H...N and C—H...π interactions. The tolyl group is disordered over two positions in a 0.852 (3:0.148 (3 ratio.

  9. Low-temperature growth of nitrogen-doped carbon nanofibers by acetonitrile catalytic CVD using Ni-based catalysts

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    Tomohiro Iwasaki


    Full Text Available Abstract To synthesize nitrogen-doped carbon nanofibers (N-CNFs at high growth rates and low temperatures less than 673 K, nickel species (metallic nickel and nickel oxide supported on alumina particles were used as the catalysts for an acetonitrile catalytic chemical vapor deposition (CVD process. The nickel:alumina mass ratio in the catalysts was fixed at 0.05:1. The catalyst precursors were prepared from various nickel salts (nitrate, chloride, sulfate, acetate, and lactate and then calcined at 1073 K for 1 h in oxidative (air, reductive (hydrogen-containing argon, or inert (pure argon atmospheres to activate the nickel-based catalysts. The effects of precursors and calcination atmosphere on the catalyst activity at low temperatures were studied. We found that the catalysts derived from nickel nitrate had relatively small crystallite sizes of nickel species and provided N-CNFs at high growth rates of 57 ± 4 g-CNF/g-Ni/h at 673 K in the CVD process using 10 vol% hydrogen-containing argon as the carrier gas of acetonitrile vapor, which were approximately 4 times larger than that of a conventional CVD process. The obtained results reveal that nitrate ions in the catalyst precursor and hydrogen in the carrier gas can contribute effectively to the activation of catalysts in low-temperature CVD. The fiber diameter and nitrogen content of N-CNFs synthesized at high growth rates were several tens of nanometers and 3.5 ± 0.3 at.%, respectively. Our catalysts and CVD process may lead to cost reductions in the production of N-CNFs.

  10. Low-temperature growth of nitrogen-doped carbon nanofibers by acetonitrile catalytic CVD using Ni-based catalysts (United States)

    Iwasaki, Tomohiro; Makino, Yuri; Fukukawa, Makoto; Nakamura, Hideya; Watano, Satoru


    To synthesize nitrogen-doped carbon nanofibers (N-CNFs) at high growth rates and low temperatures less than 673 K, nickel species (metallic nickel and nickel oxide) supported on alumina particles were used as the catalysts for an acetonitrile catalytic chemical vapor deposition (CVD) process. The nickel:alumina mass ratio in the catalysts was fixed at 0.05:1. The catalyst precursors were prepared from various nickel salts (nitrate, chloride, sulfate, acetate, and lactate) and then calcined at 1073 K for 1 h in oxidative (air), reductive (hydrogen-containing argon), or inert (pure argon) atmospheres to activate the nickel-based catalysts. The effects of precursors and calcination atmosphere on the catalyst activity at low temperatures were studied. We found that the catalysts derived from nickel nitrate had relatively small crystallite sizes of nickel species and provided N-CNFs at high growth rates of 57 ± 4 g-CNF/g-Ni/h at 673 K in the CVD process using 10 vol% hydrogen-containing argon as the carrier gas of acetonitrile vapor, which were approximately 4 times larger than that of a conventional CVD process. The obtained results reveal that nitrate ions in the catalyst precursor and hydrogen in the carrier gas can contribute effectively to the activation of catalysts in low-temperature CVD. The fiber diameter and nitrogen content of N-CNFs synthesized at high growth rates were several tens of nanometers and 3.5 ± 0.3 at.%, respectively. Our catalysts and CVD process may lead to cost reductions in the production of N-CNFs.

  11. Thermodynamics of various F420 coenzyme models as sources of electrons, hydride ions, hydrogen atoms and protons in acetonitrile. (United States)

    Xia, Ke; Shen, Guang-Bin; Zhu, Xiao-Qing


    32 F420 coenzyme models with alkylation of the three different N atoms (N1, N3 and N10) in the core structure (XFH(-)) were designed and synthesized and the thermodynamic driving forces (defined in terms of the molar enthalpy changes or the standard redox potentials in this work) of the 32 XFH(-) releasing hydride ions, hydrogen atoms and electrons, the thermodynamic driving forces of the 32 XFH˙ releasing protons and hydrogen atoms and the thermodynamic driving forces of XF(-)˙ releasing electrons in acetonitrile were determined using titration calorimetry and electrochemical methods. The effects of the methyl group at N1, N3 and N10 and a negative charge on N1 and N10 atoms on the six thermodynamic driving forces of the F420 coenzyme models and their related reaction intermediates were examined; the results show that seating arrangements of the methyl group and the negative charge have remarkably different effects on the thermodynamic properties of the F420 coenzyme models and their related reaction intermediates. The effects of the substituents at C7 and C8 on the six thermodynamic driving forces of the F420 coenzyme models and their related reaction intermediates were also examined; the results show that the substituents at C7 and C8 have good Hammett linear free energy relationships with the six thermodynamic parameters. Meanwhile, a reasonable determination of possible reactions between members of the F420 family and NADH family in vivo was given according to a thermodynamic analysis platform constructed using the elementary step thermodynamic parameter of F420 coenzyme model 2FH(-) and NADH model MNAH releasing hydride ions in acetonitrile. The information disclosed in this work can not only fill a gap in the chemical thermodynamics of F420 coenzyme models as a class of very important organic sources of electrons, hydride ions, hydrogen atoms and protons, but also strongly promote the fast development of the chemistry and applications of F420 coenzyme.

  12. Factors influencing high voltage performance of coconut char derived carbon based electrical double layer capacitor made using acetonitrile and propylene carbonate based electrolytes (United States)

    Hu, Changzheng; Qu, Weiguo; Rajagopalan, Ramakrishnan; Randall, Clive


    Symmetric EDLCs made using high purity carbon electrodes derived from coconut char were tested using 1 M Tetraethylammonium hexafluorophosphate dissolved in two different solvents namely acetonitrile and propylene carbonate. The cell voltage of the capacitor made using propylene carbonate can be extended to 3.5 V and it exhibited good cycling and thermal stability upto 70 °C while the voltage was limited to below 3.0 V in acetonitrile. XPS analysis of the positive and negative electrodes of EDLCs post cycling showed that the primary degradation products were related to ring opening reactions in propylene carbonate based electrolytes while water played a key role in degradation of acetonitrile based EDLCs.

  13. Automatized sspKa measurements of dihydrogen phosphate and Tris(hydroxymethyl) aminomethane in acetonitrile/water mixtures from 20 to 60°C. (United States)

    Acquaviva, A; Tascon, M; Padró, J M; Gagliardi, L G; Castells, C B


    We measured pKa values of Tris(hydroxymethyl)aminomethane and dihydrogen phosphate; both are commonly used to prepare buffers for reverse-phase liquid chromatography (RPLC), in acetonitrile/water mixtures from 0% to 70% (v/v) (64.6% (w/w)) acetonitrile and at 20, 30, 40, 50, and 60°C. The procedure is based on potentiometric measurements of pH of buffer solutions of variable solvent compositions using a glass electrode and a novel automated system. The method consists in the controlled additions of small volumes of a thermostated solution from an automatic buret into another isothermal solution containing exactly the same buffer-component concentrations, but a different solvent composition. The continuous changes in the solvent composition induce changes in the potentials. Thus, only two sequences of additions are needed: increasing the amount of acetonitrile from pure water and decreasing the content of acetonitrile from 70% (v/v) (64.6% (w/w)). In the procedure with homemade apparatus, times for additions, stirring, homogenization, and data acquisition are entirely controlled by software programmed for this specific routine. This rapid, fully automated method was applied to acquire more than 40 potential data covering the whole composition range (at each temperature) in about two hours and allowed a systematic study of the effect of temperature and acetonitrile composition on acid-base equilibria of two widely used substances to control pH close to 7. The experimental pKa results were fitted to empirical functions between pKa and temperature and acetonitrile composition. These equations allowed predictions of pKa to estimate the pH of mixtures at any composition and temperature, which would be very useful, for instance, during chromatographic method development.

  14. Study of the mechanism of acetonitrile stacking and its application for directly combining liquid-phase microextraction with micellar electrokinetic chromatography. (United States)

    Sun, Jingru; Feng, Jing; Shi, Ludi; Liu, Laping; He, Hui; Fan, Yingying; Hu, Shibin; Liu, Shuhui


    Acetonitrile stacking is an online concentration method that is distinctive due to its inclusion of a high proportion of organic solvent in sample matrices. We previously designed a universal methodology for the combination of liquid-phase microextraction (LPME) and capillary electrophoresis (CE) using acetonitrile stacking and micellar electrokinetic chromatography (MEKC) mode, thereby achieving large-volume injection of the diluted LPME extractant and the online concentration. In this report, the methodology was extended to the analysis of highly substituted hydrophobic chlorophenols in wines using diethyl carbonate as the extractant. Additionally, the mechanism of acetonitrile stacking was studied. The results indicated that the combination of LPME and MEKC exhibited good analytical performance: with ∼40-fold concentration by LPME, a 20-cm (33% of the total length) sample plug injection of an eight-fold dilution of diethyl carbonate with the organic solvent-saline solution produced enrichments higher by a factor of 260-791. Limits of qualification ranged from 5.5 to 16.0ng/mL. Acceptable reproducibilities of lower than 1.8% for migration time and 8.6% for peak areas were obtained. A dual stacking mechanism of acetonitrile stacking was revealed, involving transient isotachophoresis plus pH-junction stacking. The latter was associated with a pH shift induced by the presence of acetonitrile. The pseudo-stationary phase (Brij-35) played an important role in reducing the CE running time by weakening the isotachophoretic migration of the analyte ions following Cl(-) ions. The combination of acetonitrile stacking and nonionic micelle-based MEKC appears to be a perfect match for introducing water-immiscible LPME extractants into an aqueous CE system and can thus significantly expand the application of LPME-CE in green analytical chemistry.

  15. Diacetonitrile[N,N′-bis(2,6-diisopropyl­phenyl)ethane-1,2-diimine]dichloridochromium(II) acetonitrile solvate (United States)

    Peitz, Stephan; Peulecke, Normen; Müller, Bernd H.; Spannenberg, Anke; Rosenthal, Uwe


    The title compound, [CrCl2(CH3CN)2(C26H36N2)]·CH3CN, was synthesized by the reaction of CrCl2(THF)2 with N,N′-bis­(2,6-diisopropyl­phen­yl)ethane-1,2-diimine in dichloro­methane/acetonitrile. The chromium center is coordinated by two N atoms of the chelating diimine ligand, two chloride ions in a trans configuration with respect to each other, and by two N atoms of two acetonitrile mol­ecules in a distorted octa­hedral geometry. PMID:21578093

  16. 3,6-Dihydroxy-2′-[(2-hydroxy-1-naphthylmethyleneamino]xanthene-9-spiro-1′-isoindolin-3′-one acetonitrile solvate

    Directory of Open Access Journals (Sweden)

    Gen-Hua Wu


    Full Text Available The title compound, C31H20N2O5·C2H3N, was synthesized by the reaction of fluorescein hydrazide and excess 2-hydroxy-1-naphthaldehyde in acetonitrile. The spirolactam ring is planar and is nearly at right angles to the two benzene rings of the xanthene system. The dihedral angle between the two benzene rings of the xanthene system is 9.92 (4°. In the crystal structure, the molecules are linked into extended two-dimensional networks by intermolecular hydrogen bonding. Acetonitrile molecules are located in the voids between the two-dimensional networks.

  17. Spectrophotometric study on the proton transfer reaction between 2-amino-4-methylpyridine with 2,6-dichloro-4-nitrophenol in methanol, acetonitrile and the binary mixture 50% methanol + 50% acetonitrile (United States)

    Al-Ahmary, Khairia M.; Habeeb, Moustafa M.; Al-Obidan, Areej H.


    Proton transfer reaction between 2-amino-4-methylpyridine (2AMP) as the proton acceptor with 2,6-dichloro-4-nitrophenol (DCNP) as the proton donor has been investigated spectrophotometrically in methanol (MeOH), acetonitrile (AN) and a binary mixture composed of 50% MeOH and 50% AN (AN-Me). The composition of the complex has been investigated utilizing Job's and photometric titration methods to be 1:1. Minimum-maximum absorbance equation has been applied to estimate the formation constant of the proton transfer reaction (KPT) where it reached high values in the investigated solvent confirming its high stability. The formation constant recorded higher value in AN compared with MeOH and mixture of AN-Me. Based on the formation of stable proton transfer complex, a sensitive spectrophotometric method was suggested for quantitative determination of 2AMP. The Lambert-Beer's law was obeyed in the concentration range 0.5-8 μg mL- 1 with small values of limits of detection and quantification. The solid complex between 2AMP with DCNP has been synthesized and characterized by elemental analysis to be 1:1 in concordant with the molecular stoichiometry in solution. Further analysis of the solid complex was carried out using infrared and 1H NMR spectroscopy.

  18. The effect of glassy carbon surface oxides in non-aqueous voltammetry: the case of quinones in acetonitrile. (United States)

    Staley, Patrick A; Newell, Christina M; Pullman, David P; Smith, Diane K


    Glassy carbon (GC) electrodes are well-known to contain oxygenated functional groups such as phenols, carbonyls, and carboxylic acids on their surface. The effects of these groups on voltammetry in aqueous solution are well-studied, but there has been little discussion of their possible effects in nonaqueous solution. In this study, we show that the acidic functional groups, particularly phenols, are likely causes of anomalous features often seen in the voltammetry of quinones in nonaqueous solution. These features, a too small second cyclic voltammetric wave and extra current between the two waves that sometimes appears to be a small, broad third voltammetric wave, have previously been attributed to different types of dimerization. In this work, concentration-dependent voltammetry in acetonitrile rules out dimerization with a series of alkyl-benzoquinones because the anomalous features get larger as the concentration decreases. At low concentrations, solution bimolecular reactions will be relatively less important than reactions with surface groups. Addition of substoichiometric amounts of naphthol at higher quinone concentrations produces almost identical behavior as seen at low quinone concentrations with no added naphthol. This implicates hydrogen bonding and proton transfer from the surface phenolic groups as the cause of the anomalous features in quinone voltammetry at GC electrodes. This conclusion is supported by the perturbation of surface oxide coverage on GC electrodes through different electrode pretreatments.

  19. Rate theory of solvent exchange and kinetics of Li(+) - BF4 (-)/PF6 (-) ion pairs in acetonitrile. (United States)

    Dang, Liem X; Chang, Tsun-Mei


    In this paper, we describe our efforts to apply rate theories in studies of solvent exchange around Li(+) and the kinetics of ion pairings in lithium-ion batteries (LIBs). We report one of the first computer simulations of the exchange dynamics around solvated Li(+) in acetonitrile (ACN), which is a common solvent used in LIBs. We also provide details of the ion-pairing kinetics of Li(+)-[BF4] and Li(+)-[PF6] in ACN. Using our polarizable force-field models and employing classical rate theories of chemical reactions, we examine the ACN exchange process between the first and second solvation shells around Li(+). We calculate exchange rates using transition state theory and weighted them with the transmission coefficients determined by the reactive flux, Impey, Madden, and McDonald approaches, and Grote-Hynes theory. We found the relaxation times changed from 180 ps to 4600 ps and from 30 ps to 280 ps for Li(+)-[BF4] and Li(+)-[PF6] ion pairs, respectively. These results confirm that the solvent response to the kinetics of ion pairing is significant. Our results also show that, in addition to affecting the free energy of solvation into ACN, the anion type also should significantly influence the kinetics of ion pairing. These results will increase our understanding of the thermodynamic and kinetic properties of LIB systems.

  20. Protective effects of 6-hydroxy-1-methylindole-3-acetonitrile on cisplatin-induced oxidative nephrotoxicity via Nrf2 inactivation. (United States)

    Moon, Ji Hee; Shin, Ji-Sun; Kim, Jong-Bin; Baek, Nam-In; Cho, Young-Wuk; Lee, Yong Sup; Kay, Hee Yeon; Kim, Soo-dong; Lee, Kyung-Tae


    We previously demonstrated the ethanol extract of the roots of Brassica rapa protects against cisplatin-induced nephrotoxicity by attenuating oxidative stress. Here, we investigated the nephroprotective effects of 6-hydroxy-1-methylindole-3-acetonitrile (6-HMA), which was isolated from the roots of B. rapa, on cisplatin-induced toxicity in renal epithelial LLC-PK1 cells and in rats with acute renal injury. Pretreatment of LLC-PK1 cells with 6-HMA ameliorated cisplatin-induced cytotoxicity caused by oxidative stress, as was demonstrated by reductions in the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) and increased levels of glutathione (GSH). In addition, 6-HMA inhibited cisplatin-induced heme oxygenase-1 (HO-1) expression, possibly due to the suppression of the nuclear translocation and binding activity of NF-E2-related factor 2 (Nrf2). Furthermore, 6-HMA administered rats showed lower levels of blood urea nitrogen (BUN), creatinine, and urinary lactate dehydrogenase (LDH) than cisplatin alone-treated rats in cisplatin-induced renal injury model. Moreover, 6-HMA inhibited the cisplatin-induced formation of MDA and GSH depletion and increased the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GR). Taken together, these findings indicate 6-HMA is a major active constituent from the roots of B. rapa to have a protective effect against cisplatin-induced nephrotoxicity by attenuating oxidative stress.

  1. Spectroscopic studies and molecular orbital calculations of charge transfer complexation between 3,5-dimethylpyrazole with DDQ in acetonitrile. (United States)

    Habeeb, Moustafa M; Al-Attas, Amirah S; Al-Raimi, Doaa S


    Charge transfer (CT) interaction between 3,5-dimethylpyrazole (DMP) with the π-acceptor 2,3-dichloro-5,6-dicyano-p-benzoquinon (DDQ) has been investigated spectrophotometrically in acetonitrile (AN). Simultaneous reddish brown color has been observed upon mixing donor with acceptor solutions attributing to CT complex formation. The electronic spectra of the formed complex exhibited multi-charge transfer bands at 429, 447, 506, 542 and 589nm, respectively. Job(')s method of continuous variations and spectrophotometric titration methods confirmed the formation of the studied complex in 1:2 ratio between DMP and DDQ. Benesi-Hildebrand equation has been applied to calculate the stability constant of the formed complex where it recorded high value supporting formation of stable complex. Molecular orbital calculations using MM2 method and GAMESS (General Atomic and Molecular Electronic Structure System) interface computations as a package of ChemBio3D Ultra12 software were carried out for more analysis of the formed complex in the gas phase. The computational analysis included energy minimisation, stabilisation energy, molecular geometry, Mullikan charges, molecular electrostatic potential (MEP) surfaces of reactants and complex as well as characterization of the higher occupied molecular orbitals (HOMO) and lower unoccupied molecular orbitals (LUMO) surfaces of the complex. A good consistency between experimental and theoretical results has been recorded.

  2. Stability improvement of gel-state dye-sensitized solar cells by utilization the co-solvent effect of propionitrile/acetonitrile and 3-methoxypropionitrile/acetonitrile with poly(acrylonitrile-co-vinyl acetate) (United States)

    Venkatesan, Shanmugam; Su, Song-Chuan; Kao, Shon-Chen; Teng, Hsisheng; Lee, Yuh-Lang


    Propionitrile (PPN) or 3-methoxypropionitrile (MPN) is mixed with acetonitrile (ACN) to prepare ACN/PPN and ACN/MPN co-solvents and used to fabricate polymer gel electrolytes (PGEs) of dye-sensitized solar cells (DSSCs), aiming at improving the stability of gel-state DSSCs. Co-solvents with various ratios are utilized to prepare PGEs using poly(acrylonitrile-co-vinyl acetate) (PAN-VA) as the gelator. The ratio effects of the co-solvents on the properties of PGEs and the performances of the corresponding DSSCs are studied. The results show that in-situ gelation of the gel-electrolytes can still be performed at the presence of 40% PPN or 30% MPN. However, increasing the composition of PPN and MPN in the co-solvents triggers a decrease in the diffusivity and conductivity of the PGEs, but an increase in the viscosity. Therefore, the energy conversion efficiencies of the cells decrease as a result. However, the introduction of PPN and MPN elevates the gel-to-liquid transition temperature (Tp) of the PGEs which significantly increases the stability of the gel-state DSSCs. Comparing between the effects of the two co-solvents, PPN and MPN have similar effect on elevation of Tp, but the conductivity of PGEs and the corresponding cell efficiency are higher for the ACN/PPN system, attributed to its lower viscosity compared with ACN/MPN system. By using the ACN/PPN (60/40) co-solvent at the presence of TiO2 fillers, gel-state cell with an efficiency of 8.3% can be achieved, which is even higher than that obtained by the liquid state cell (8%). After 500 h test at 60 °C, the cell can retain 95.4% of its initial efficiency.

  3. Europium, uranyl, and thorium-phenanthroline amide complexes in acetonitrile solution: an ESI-MS and DFT combined investigation. (United States)

    Xiao, Cheng-Liang; Wang, Cong-Zhi; Mei, Lei; Zhang, Xin-Rui; Wall, Nathalie; Zhao, Yu-Liang; Chai, Zhi-Fang; Shi, Wei-Qun


    The tetradentate N,N'-diethyl-N,N'-ditolyl-2,9-diamide-1,10-phenanthroline (Et-Tol-DAPhen) ligand with hard-soft donor atoms has been demonstrated to be promising for the group separation of actinides from highly acidic nuclear wastes. To identify the formed complexes of this ligand with actinides and lanthanides, electrospray ionization mass spectrometry (ESI-MS) combined with density functional theory (DFT) calculations was used to probe the possible complexation processes. The 1 : 2 Eu-L species ([EuL2(NO3)](2+)) can be observed in ESI-MS at low metal-to-ligand ([M]/[L]) ratios, whereas the 1 : 1 Eu-L species ([EuL(NO3)2](+)) can be observed when the [M]/[L] ratio is higher than 1.0. However, ([UO2L(NO3)](+)) is the only detected species for the uranyl complexes. The [ThL2(NO3)2](2+) species can be observed at low [M]/[L] ratios; the 1 : 2 species ([ThL2(NO3)](3+)) and a new 1 : 1 species ([ThL(NO3)3](+)) can be detected at high [M]/[L] ratios. Collision-induced dissociation (CID) results showed that Et-Tol-DAPhen ligands can coordinate strongly with metal ions, and the coordination moieties remain intact under CID conditions. Natural bond orbital (NBO), molecular electrostatic potential (MEP), electron localization function (ELF), atoms in molecules (AIM) and molecular orbital (MO) analyses indicated that the metal-ligand bonds of the actinide complexes exhibited more covalent character than those of the lanthanide complexes. In addition, according to thermodynamic analysis, the stable cationic M-L complexes in acetonitrile are found to be in good agreement with the ESI-MS results.

  4. Acetonitrile extraction and dual-layer solid phase extraction clean-up for pesticide residue analysis in propolis. (United States)

    Oellig, Claudia


    Propolis is a very complex mixture of substances that is produced by honey bees and is known to be a rather challenging matrix for residue analysis. Besides resins, flavonoids and phenols, high amount of wax is co-extracted resulting in immense matrix effects. Therefore a suitable clean-up is crucial and indispensable. In this study, a reliable solid phase extraction (SPE) clean-up was developed for pesticide residue analysis in propolis. The clean-up success was quickly and easily monitored by high-performance thin-layer chromatography with different detection possibilities. The final method consists of the extraction of propolis with acetonitrile according to the QuEChERS method followed by an effective extract purification on dual-layer SPE cartridges with spherical hydrophobic polystyrene-divinylbenzene resin/primary secondary amine as sorbent and a mixture of toluene/acetone (95:5, v/v) for elution. Besides fat-soluble components like waxes, flavonoids, and terpenoids, more polar compounds like organic acids, fatty acids, sugars and anthocyanins were also removed to large extent. Method performance was assessed by recovery experiments at spiking levels of 0.5 and 1mg/kg (n=5) for fourteen pesticides that are relevant for propolis. Mean recoveries determined by HPLC-MS against solvent standards were between 40 and 101%, while calculation against matrix-matched standards provided recoveries of 79-104%. Precision of recovery, assessed by relative standard deviations, were below 9%. Thus, the developed dual-layer SPE clean-up enables the reliable pesticide residue analysis in propolis and provides a suitable alternative to time-consuming clean-up procedures proposed in literature.

  5. The response behavior of PPy-DB18C6 electrode to terbium(III in acetonitrile and its thermodynamic application

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein Arbab Zavar


    Full Text Available Polypyrrole modified electrode prepared by electropolymerization of pyrrole in the presence of a complexing ligand, dibenzo-18-crown-6(DB18C6, was prepared and investigated as a Tb3+-selective electrode in acetonitrile. The potentiometric response of the electrode was linear within the Tb3+ concentration range 1 × 10−5–1 × 10−2 M with a Nernstian slope of 20.9 mVdecade−1 in AN. The electrode was applied to study the complexation of the terbium(III ion in acetonitrile with such other basic aprotic solvent molecules (D as dimethyl sulfoxide, N,N-dimethyl formamide, propylene carbonate and pyridine. The successive complex formation constant (βi and Gibbs energies of transfer (ΔGtr of Tb3+ in AN in relation to such D were obtained.

  6. Effect of ZnI2 cosolute on quality and performance of γ-CuI ultrafast scintillation crystal grown via evaporation method in acetonitrile solvent (United States)

    Yue, Shuangqiang; Gu, Mu; Liu, Xiaolin; Zhang, Juannan; Huang, Shiming; Liu, Bo; Ni, Chen


    γ-CuI single crystal was grown via evaporation method in ZnI2 acetonitrile solvent. The ZnI2 plays a unique role which can not only increase the solubility of CuI in acetonitrile but also introduce the Zn and I ions in the crystal. The γ-CuI crystal grown in ZnI2 acetonitrile is regular and transparent. Its size reaches up to 18 × 11 × 2 mm3 which is larger than that of the crystal grown in pure acetonitrile. In terms of the photoluminescence, the intensity of the emission at 411 nm of the crystal grown with ZnI2 as a cosolute is much higher than that of the crystal grown without ZnI2, which implies that the crystallinity of the crystal can be improved by ZnI2 doping. The X-ray excited luminescence of the crystal shows that the emission at 435 nm can be significantly enhanced and the emission near 680 nm can be suppressed by introducing Zn and I in the natural non-stoichiometry γ-CuI crystal. The nature of the phenomena is discussed. The decay time of the emission at 435 nm similar to that of the emission at 411 nm is faster than the detection limit of the instrument, i.e. less than 1 ns, and the average decay time of the emission near 680 nm is about 183 ns. The results can provide a useful guide to optimize the scintillation properties of γ-CuI single crystal.

  7. Influence of solvents on species crossover and capacity decay in non-aqueous vanadium redox flow batteries: Characterization of acetonitrile and 1, 3 dioxolane solvent mixture (United States)

    Bamgbopa, Musbaudeen O.; Almheiri, Saif


    The importance of the choice of solvent in a non-aqueous redox flow battery (NARFB) cannot be overemphasized. Several studies demonstrated the influence of the solvent on electrolyte performance in terms of reaction rates, energy/power densities, and efficiencies. In this work, we investigate capacity decay as a direct consequence of varying reactant crossover rates through membranes in different solvent environments. Specifically, we demonstrate the superiority of an 84/16 vol% acetonitrile/1,3 dioxolane solvent mixture over pure acetonitrile in terms of energy efficiency (up to 89%) and capacity retention for vanadium NARFBs - while incorporating a Nafion 115 membrane. The permeability of Nafion to the vanadium acetylacetonate active species is an order of magnitude lower when pure acetonitrile is replaced by the solvent mixture. A method to estimate relative membrane permeability is formulated from numerical analysis of self-discharge experimental data. Furthermore, tests on a modified Nafion/SiO2 membrane, which generally offered low species permeability, also show that different solvents alter membrane permeability. Elemental and morphological analyses of cycled Nafion and NafionSi membranes in different solvent environments indicate that different crossover rates induced by the choice of solvent during cycling are due to changes in the membrane microstructure, intrinsic permeability, swelling rates, and chemical stability.

  8. High performance liquid chromatography for the simultaneous analysis of penicillin residues in beef and milk using ion-paired extraction and binary water-acetonitrile mixture. (United States)

    Kukusamude, Chunyapuk; Burakham, Rodjana; Chailapakul, Orawon; Srijaranai, Supalax


    An ion-paired extraction (IPE) has been developed for the analysis of penicillin antibiotics (penicillin G, oxacillin and cloxacillin) in beef and milk samples using tetrabutylammonium bromide (TBABr) as ion-pairing agent and binary water-acetonitrile as extractant. The factors affecting the IPE efficiency were optimized including solution pH, volume of acetonitrile (ACN), concentration of TBABr and electrolyte salt (NH(4))(2)SO(4). The optimum IPE conditions were 10 mmol L(-1) phosphate buffer pH 8, 2 mL of ACN, 6 mmol L(-1) of TBABr and 2.5 mL of saturated ammonium sulfate. Under the HPLC condition: an Xbridge™ C18 reversed-phase column, isocratic elution of 5 mmol L(-1) phosphate buffer (pH 6.6) and acetonitrile (75:25, v/v) and a flow rate of 1 mL min(-1), with UV detection at 215 nm, the separation of three penicillins was achieved within 10 min. Under the selected optimum conditions, the enhancement of 21-53 folds compared to that without preconcentration and limits of detection (LODs) of 1-2 ng mL(-1) were obtained. Good reproducibility was achieved with RSDpenicillin residues in beef and milk with LOD lower than the maximum residue limits.

  9. Association of ionic liquids in solution: a combined dielectric and conductivity study of [bmim][Cl] in water and in acetonitrile. (United States)

    Bešter-Rogač, Marija; Stoppa, Alexander; Hunger, Johannes; Hefter, Glenn; Buchner, Richard


    Ion association of the ionic liquid [bmim][Cl] in acetonitrile and in water was studied by dielectric spectroscopy for salt concentrations c ≤ 1.3 M at 298.15 K and by measurement of molar electrical conductivities, Λ, of dilute solutions (c ≤ 0.006 M) in the temperature range 273.15 ≲ T/K ≤ 313.15. Whilst acetonitrile solutions of [bmim][Cl] exhibit moderate ion pairing, with an association constant of K°(A) ≈ 60 M(-1) and increasing with temperature, [bmim][Cl] is only weakly associated in water (K°(A) ≈ 6 M(-1)) and ion pairing decreases with rising temperature. Only contact ion pairs were detected in both solvents. Standard-state enthalpy, entropy and heat capacity changes of ion association were derived, as well as the activation enthalpy of charge transport and the limiting conductivity of the cation, λ(∞) ([bmim](+)). These data, in conjunction with effective solvation numbers obtained from the dielectric spectra, suggest that the solvation of [bmim](+) is much weaker in water than in acetonitrile.

  10. Determination of strobilurin fungicides in cotton seed by combination of acetonitrile extraction and dispersive liquid-liquid microextraction coupled with gas chromatography. (United States)

    Xue, Jiaying; Li, Huichen; Liu, Fengmao; Jiang, Wenqing; Chen, Xiaochu


    The simultaneous determination of four strobilurin fungicides (picoxystrobin, kresoxim-methyl, trifloxystrobin, and azoxystrobin) in cotton seed by combining acetonitrile extraction and dispersive liquid-liquid microextraction was developed prior to GC with electron capture detection. Several factors, including the type and volume of the extraction and dispersive solvents, extraction condition and time, and salt addition, were optimized. The analytes were extracted with acetonitrile from cotton seed and the clean-up was carried out by primary secondary amine. Afterwards, 60 μL of n-hexane/toluene (1:1, v/v) with a lower density than water was mixed with 1 mL of the acetonitrile extract, then the mixture was injected into 7 mL of distilled water. A 0.1 mL pipette was used to collect a few microliters of n-hexane/toluene from the top of the aqueous solution. The enrichment factors of the analytes ranged from 36 to 67. The LODs were in the range of 0.1 × 10(-3) -2 × 10(-3) mg/kg. The relative recoveries varied from 87.7 to 95.2% with RSDs of 4.1-8.5% for the four fungicides. The good performance of the method, compared with the conventional pretreatments, has demonstrated it is suitable for determining low concentrations of strobilurin fungicide residues in cotton seed.

  11. Determination of multiresidues in rapeseed, rapeseed oil, and rapeseed meal by acetonitrile extraction, low-temperature cleanup, and detection by liquid chromatography with tandem mass spectrometry. (United States)

    Jiang, Yaping; Li, Yanjie; Jiang, Yuting; Li, Jianguo; Pan, Canping


    A multiresidue method for determining pesticides in rapeseed, rapeseed oil, and rapeseed meal by use of liquid chromatography-tandem mass spectrometry is developed. Samples were extracted with acetonitrile or acidified acetonitrile and cleaned up by a 12 h freezing step. The recovery data were obtained by spiking blank samples at three concentration levels. The recoveries of 27 selected pesticides in rapeseed, rapeseed oil, and rapeseed meal were in the range of 70-118%, at the concentration level of 10 μg kg(-1), with intraday and interday precisions of lower than 22 and 27%, respectively. Linearity was studied between 2 and 500 μg L(-1) with determination coefficients (R(2)) of higher than 0.98 for all compounds in the three matrices. The limits of quantitation (LOQs) of pesticides in rapeseed, rapeseed oil, and rapeseed meal ranged from 0.3 to 18 μg kg(-1). The n-octanol-water partition coefficient showed more influence than water solubility in extracting pesticides by acetonitrile from matrices of high fat content. This method was successfully applied for routine analysis in commercial products.

  12. A novel strategy for acetonitrile wastewater treatment by using a recombinant bacterium with biofilm-forming and nitrile-degrading capability. (United States)

    Li, Chunyan; Yue, Zhenlei; Feng, Fengzhao; Xi, Chuanwu; Zang, Hailian; An, Xuejiao; Liu, Keran


    There is a great need for efficient acetonitrile removal technology in wastewater treatment to reduce the discharge of this pollutant in untreated wastewater. In this study, a nitrilase gene (nit) isolated from a nitrile-degrading bacterium (Rhodococcus rhodochrous BX2) was cloned and transformed into a biofilm-forming bacterium (Bacillus subtilis N4) that expressed the recombinant protein upon isopropylthio-β-galactoside (IPTG) induction. The recombinant bacterium (B. subtilis N4-pHT01-nit) formed strong biofilms and had nitrile-degrading capability. Further testing demonstrated that biofilms formed by B. subtilis N4-pHT01-nit were highly resistant to loading shock from acetonitrile and almost completely degraded the initial concentration of acetonitrile (800 mg L(-1)) within 24 h in a moving bed biofilm reactor (MBBR) after operation for 35 d. The bacterial composition of the biofilm, identified by high-throughput sequencing, in a reactor in which the B. subtilis N4-pHT01-nit bacterium was introduced indicated that the engineered bacterium was successfully immobilized in the reactor and became dominant genus. This work demonstrates that an engineered bacterium with nitrile-degrading and biofilm-forming capacity can improve the degradation of contaminants in wastewater. This approach offers a novel strategy for enhancing the biological oxidation of toxic pollutants in wastewater.

  13. Thermodynamic diagnosis of the properties and mechanism of dihydropyridine-type compounds as hydride source in acetonitrile with "Molecule ID Card". (United States)

    Zhu, Xiao-Qing; Tan, Yue; Cao, Chao-Tun


    A series of 45 dihydropyridine-type organic compounds as hydride source were designed and synthesized. The thermodynamic driving forces (defined as enthalpy changes or redox potentials in this work) of the dihydropyridines to release hydride anions, hydrogen atoms (hydrogen for short), and electrons in acetonitrile, the thermodynamic driving forces of the radical cations of the dihydropyridines to release protons and hydrogens in acetonitrile, and the thermodynamic driving forces of the neutral pyridine-type radicals of the dihydropyridines to release electron in acetonitrile were determined by using titration calorimetry and electrochemical methods. The rates and activation parameters of hydride transfer from the dihydropyridines to acridinium perclorate, a well-known hydride acceptor, were determined by using UV-vis absorption spectroscopy technique. The relationship between the thermodynamic driving forces and kinetic rate of the hydride transfer was examined. Thermodynamic characteristic graph (TCG) of the dihydropyridines as an efficient "Molecule ID Card" was introduced. The TCG can be used to quantitatively diagnose or predict the characteristic chemical properties of the dihydropyridines and their various reaction intermediates. The mechanism of hydride transfer from the dihydropyridines to acridinium perclorate was diagnosed and elucidated by using the determined thermodynamic parameters and the activation parameters.

  14. Modulation of intra- and inter-sheet interactions in short peptide self-assembly by acetonitrile in aqueous solution (United States)

    Deng, Li; Zhao, Yurong; Zhou, Peng; Xu, Hai; Wang, Yanting


    Besides our previous experimental discovery (Zhao Y R, et al. 2015 Langmuir, 31, 12975) that acetonitrile (ACN) can tune the morphological features of nanostructures self-assembled by short peptides KIIIIK (KI4K) in aqueous solution, further experiments reported in this work demonstrate that ACN can also tune the mass of the self-assembled nanostructures. To understand the microscopic mechanism how ACN molecules interfere peptide self-assembly process, we conducted a series of molecular dynamics simulations on a monomer, a cross-β sheet structure, and a proto-fibril of KI4K in pure water, pure ACN, and ACN-water mixtures, respectively. The simulation results indicate that ACN enhances the intra-sheet interaction dominated by the hydrogen bonding (H-bonding) interactions between peptide backbones, but weakens the inter-sheet interaction dominated by the interactions between hydrophobic side chains. Through analyzing the correlations between different groups of solvent and peptides and the solvent behaviors around the proto-fibril, we have found that both the polar and nonpolar groups of ACN play significant roles in causing the opposite effects on intermolecular interactions among peptides. The weaker correlation of the polar group of ACN than water molecule with the peptide backbone enhances H-bonding interactions between peptides in the proto-fibril. The stronger correlation of the nonpolar group of ACN than water molecule with the peptide side chain leads to the accumulation of ACN molecules around the proto-fibril with their hydrophilic groups exposed to water, which in turn allows more water molecules close to the proto-fibril surface and weakens the inter-sheet interactions. The two opposite effects caused by ACN form a microscopic mechanism clearly explaining our experimental observations. Project supported by the National Basic Research Program of China (Grant No. 2013CB932804), the National Natural Science Foundation of China (Grant Nos. 91227115, 11421063

  15. Separation of methanol-acetonitrile by extractive distillation%萃取精馏分离甲醇-乙腈的研究

    Institute of Scientific and Technical Information of China (English)

    于洋; 白鹏; 庄琼红


    为了分离甲醇-乙腈共沸混合物,研究了萃取精馏在甲醇-乙腈共沸物系中的应用.通过溶剂极性比较初选出萃取精馏溶剂,由ChemCAD软件模拟和气液平衡实验验证选定出合适的溶剂用于萃取精馏分离甲醇-乙腈共沸混合物,通过萃取精馏实验考察了所选萃取精馏溶剂的效果.结果表明:N,N-二甲基甲酰胺(DMF)能够消除甲醇-乙腈共沸物系的共沸.采用Wilson模型对常压下甲醇-乙腈物系和加入溶剂N,N-二甲基甲酰胺的汽液平衡进行模拟,模拟数据与实验结果吻合较好.采用有33块理论板,其中净化回收段填料层3块理论板,萃取精馏段填料层30块理论板的填料塔进行间歇萃取精馏实验分离甲醇-乙腈共沸混合物,回流比为4,溶剂质量比为3∶1时在塔顶得到产品甲醇质量分数为95.76%.说明N,N-二甲基甲酰胺作为溶剂的萃取精馏分离甲醇-乙腈共沸混合物是可行的.%In order to separate methanol-acetonitrile azeotropic mixture, the application of extractive distillation to separation of methanol-acetonitrile was researched.By comparing solvent polarity, the simulation by ChemCAD software and VLE experiment were used to select the suitable solvent for the separation of methanol-acetonitrile azeotropic mixture by extractive distillation.The effectiveness of the solvent selected was investigated by the extractive distillation experiments.The results show that N,N-dimethyfformamide (DMF) as solvent can break the azeotrope ot methanol-acetonitrile system.Wilson model was used in the simulation of the VLE of methanol-acetonitrile system as well as when DMF was added under atmospheric pressure.The simulation data agree well with the experimental results.The experiment of separation of azeotropic mixture of methanol and acetonitrile by batch extractive distillation was carried out in a packed column of 33 theoretical plates.The purification and recovery section has 3 theoretical plates and

  16. Intramolecular charge transfer with crystal violet lactone in acetonitrile as a function of temperature: reaction is not solvent-controlled. (United States)

    Druzhinin, Sergey I; Demeter, Attila; Zachariasse, Klaas A


    Intramolecular charge transfer (ICT) with crystal violet lactone (CVL) in the excited singlet state takes place in solvents more polar than n-hexane, such as ethyl acetate, tetrahydrofuran, and acetonitrile (MeCN). In these solvents, the fluorescence spectrum of CVL consists of two emission bands, from a locally excited (LE) and an ICT state. The dominant deactivation channel of the lowest excited singlet state is internal conversion, as the quantum yields of fluorescence (0.007) and intersystem crossing (0.015) in MeCN at 25 °C are very small. CVL is a weakly coupled electron donor/acceptor (D/A) molecule, similar to an exciplex (1)(A(-)D(+)). A solvatochromic treatment of the LE and ICT emission maxima results in the dipole moments μe(LE) = 17 D and μe(ICT) = 33 D, much larger than those previously reported. This discrepancy is attributed to different Onsager radii and spectral fluorimeter calibration. The LE and ICT fluorescence decays of CVL in MeCN are double exponential. As determined by global analysis, the LE and ICT decays at 25 °C have the times τ2 = 9.2 ps and τ1 = 1180 ps, with an amplitude ratio of 35.3 for LE. From these parameters, the rate constants ka = 106 × 10(9) s(-1) and kd = 3.0 × 10(9) s(-1) of the forward and backward reaction in the LE ⇄ ICT equilibrium are calculated, resulting in a free enthalpy difference ΔG of -8.9 kJ/mol. The amplitude ratio of the ICT fluorescence decay equals -1.0, which signifies that the ICT state is not prepared by light absorption in the S0 ground state, but originates exclusively from the directly excited LE precursor. From the temperature dependence of the fluorescence decays of CVL in MeCN (-45 to 75 °C), activation energies E(a) = 3.9 kJ/mol (LE → ICT) and E(d) = 23.6 kJ/mol (ICT → LE) are obtained, giving an enthalpy difference ΔH (= E(a) - E(d)) of -19.7 kJ/mol, and an entropy difference ΔS = -35.5 J mol(-1) K(-1). These data show that the ICT reaction of CVL in MeCN is not barrierless

  17. 高纯乙腈连续精馏过程建模与分析%Modeling and analyzing of continuous process for rectifying high purity acetonitrile

    Institute of Scientific and Technical Information of China (English)

    曾涵卫; 孙小方; 蔡亦军; 夏陆岳; 周猛飞; 潘海天


    Based on the deep analysis of continuous process of rectifying high purity acetonitrile and its mechanics, with rational assumptions dynamic mathematical models of multi - tower for rectifying high purity acetonitrile were established by material balance, energy balance, environmental impact and hydraulic analysis, considering the character of multi-stage cascade and the difficulty of operating conditions optimization. Furthermore, the dynamic simulation and analysis were carried out respectively to the dealcoholization tower, vacuum tower and pressure tower. Simultaneously, investigating the tower pressure and steam heating effect on the separation process, and finding the further relative dynamic data of acetonitrile could provide a good foundation for the research of system integration optimization and control.%针对高纯乙腈连续精馏过程多塔串级及操作条件优化困难等特点,在深入分析乙腈连续精馏工艺流程及机理基础上,通过物料衡算、能量衡算、环境影响衡算和水力学分析等原理,结合必要的合理假设,建立乙腈连续精馏多塔的动态数学模型,对脱醇塔、减压塔和加压塔分别进行动态模拟和分析,考察塔内压力、加热蒸汽量等对分离过程的影响,并进一步寻找这些因素对出料乙腈的动态变化数据,为实施系统的集成优化与控制提供了良好基础.

  18. Dichlorido(4′-ferrocenyl-2,2′:6′,2′′-terpyridine-κ3N,N′,N′′zinc acetonitrile monosolvate

    Directory of Open Access Journals (Sweden)

    Si-Ping Tang


    Full Text Available The title complex, [FeZn(C5H5Cl2(C20H14N3]·CH3CN, is composed of one ZnII atom, one 4′-ferrocenyl-2,2′:6′,2′′-terpyridine (fctpy ligand, two Cl atoms and one acetonitrile solvent molecule. The ZnII atom is five-coordinated in a trigonal–bipyramidal geometry by the tridentate chelating fctpy ligand and two Cl atoms.

  19. Oxygen transfer from an intramolecularly coordinated diaryltellurium oxide to acetonitrile. Formation and combined AIM and ELI-D analysis of a novel diaryltellurium acetimidate. (United States)

    Mallow, Ole; Bolsinger, Jens; Finke, Pamela; Hesse, Malte; Chen, Yu-Sheng; Duthie, Andrew; Grabowsky, Simon; Luger, Peter; Mebs, Stefan; Beckmann, Jens


    The reaction of the intramolecularly coordinated diaryltellurium(IV) oxide (8-Me2NC10H6)2TeO with acetonitrile proceeds with oxygen transfer and gives rise to the formation of the novel zwitterionic diaryltelluronium(IV) acetimidate (8-Me2NC10H6)2TeNC(O)CH3 (1) in 57% yield. Hydrolysis of 1 with hydrochloric acid affords acetamide and the previously known diarylhydroxytelluronium(IV) chloride [(8-Me2NC10H6)2Te(OH)]Cl.

  20. Determination of diflubenzuron and chlorbenzuron in fruits by combining acetonitrile-based extraction with dispersive liquid-liquid microextraction followed by high-performance liquid chromatography. (United States)

    Ruan, Chunqiang; Zhao, Xiang; Liu, Chenglan


    In this study, a simple and low-organic-solvent-consuming method combining an acetonitrile-partitioning extraction procedure followed by "quick, easy, cheap, effective, rugged and safe" cleanup with ionic-liquid-based dispersive liquid-liquid microextraction and high-performance liquid chromatography with diode array detection was developed for the determination of diflubenzuron and chlorbenzuron in grapes and pears. Ionic-liquid-based dispersive liquid-liquid microextraction was performed using the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate as the extractive solvent and acetonitrile extract as the dispersive solvent. The main factors influencing the efficiency of the dispersive liquid-liquid microextraction were evaluated, including the extractive solvent type and volume and the dispersive solvent volume. The validation parameters indicated the suitability of the method for routine analyses of benzoylurea insecticides in a large number of samples. The relative recoveries at three spiked levels ranged between 98.6 and 109.3% with relative standard deviations of less than 5.2%. The limit of detection was 0.005 mg/kg for the two insecticides. The proposed method was successfully used for the rapid determination of diflubenzuron and chlorbenzuron residues in real fruit samples.

  1. Structural and spectroscopic characterization of methyl isocyanate, methyl cyanate, methyl fulminate, and acetonitrile N-oxide using highly correlated ab initio methods (United States)

    Dalbouha, S.; Senent, M. L.; Komiha, N.; Domínguez-Gómez, R.


    Various astrophysical relevant molecules obeying the empirical formula C2H3NO are characterized using explicitly correlated coupled cluster methods (CCSD(T)-F12). Rotational and rovibrational parameters are provided for four isomers: methyl isocyanate (CH3NCO), methyl cyanate (CH3OCN), methyl fulminate (CH3ONC), and acetonitrile N-oxide (CH3CNO). A CH3CON transition state is inspected. A variational procedure is employed to explore the far infrared region because some species present non-rigidity. Second order perturbation theory is used for the determination of anharmonic frequencies, rovibrational constants, and to predict Fermi resonances. Three species, methyl cyanate, methyl fulminate, and CH3CON, show a unique methyl torsion hindered by energy barriers. In methyl isocyanate, the methyl group barrier is so low that the internal top can be considered a free rotor. On the other hand, acetonitrile N-oxide presents a linear skeleton, C3v symmetry, and free internal rotation. Its equilibrium geometry depends strongly on electron correlation. The remaining isomers present a bend skeleton. Divergences between theoretical rotational constants and previous parameters fitted from observed lines for methyl isocyanate are discussed on the basis of the relevant rovibrational interaction and the quasi-linearity of the molecular skeleton.

  2. Thermal Thiocyanate Ligand Substitution Kinetics of the Solar Cell Dye N719 by Acetonitrile, 3-Methoxypropionitrile, and 4-tert-Butylpyridine

    DEFF Research Database (Denmark)

    Nguyen, Thai Hoang; Minh, Ha; Lund, Torben


    the same products as occur in the homogenous solutions; however, the reactions are approximately 10 times faster. For the reaction of a colloidal mixture of N719-dyed TiO2 particles in acetonitrile containing 0.5 M 4-TBP, a t1/2(het) of 120 h was calculated at 85°C. The N719-based DSSC cells...... in both homogenous solutions and colloidal mixtures of N719-dyed TiO2 nanocrystalline particles. Thiocyanate ligand substitution by the solvents (S) acetonitrile or 3-methoxypropionitrile in homogeneous solutions occurs at elevated temperatures (80-110°C) by means of a simple slow pseudo......-first-order reaction leading to the formation of the product [RuL2(NCS)(S)]+ with a half life time t1/2  ~ 2000 h of N719 at 80 ºC. If tert-butylpyridine (0.5 M) is added, the end product instead becomes [RuL2(NCS)(4-TBP)]+  with a t1/2 ~1000 h. When N719 is bound to TiO2 particles, the reactions with S and 4-TBP give...

  3. catena-Poly[[[iodidocopper(I]-{μ-N-[(pyridin-2-yl-κNmethylidene]pyridin-3-amine-κ2N3:N1}] acetonitrile hemisolvate

    Directory of Open Access Journals (Sweden)

    Ali Mahmoudi


    Full Text Available In the asymmetric unit of the title polymeric complex, {[CuI(C11H9N3]·0.5CH3CN}n, there are two CuI atoms, two N-[(pyridin-2-yl-κNmethylidene]pyridin-3-amine (PyPy ligands and two I atoms. Both CuI atoms have a distorted tetrahedral geometry, each being coordinated by one I atom, two N atoms of one PyPy ligand and one N atom from an adjacent PyPy ligand. In the crystal, infinite helical chains of [Cu2(PyPy2]n are formed propagating along the b axis. These chains are linked via weak C—H...I hydrogen bonds and π–π stacking interactions [shortest centroid–centroid distance = 3.2727 (14 Å]. During the refinement, electron-density peaks were located that were believed to be highly disordered solvent molecules (possibly acetonitrile. The SQUEEZE option in PLATON [Spek (2009. Acta Cryst. D65, 148–155] indicated there were solvent cavities with a total volume of 196 Å3 containing approximately 60 electrons per unit cell, which equated to one molecule of acetonitrile per asymmetric unit.

  4. μ-Hexa-thio-metadiphosphato-bis-[(1,4,7,10,13,16-hexa-oxa-cyclo-octa-decane-κ(6) O)rubidium] aceto-nitrile disolvate. (United States)

    Gjikaj, Mimoza; Pook, Niels-Patrick; Qarri, Flora


    The asymmetric unit of the title compound, [Rb2(P2S6)(C12H24O6)2]·2CH3CN, contains one half of an [Rb(18-crown-6)2]2[P2S6] unit and one aceto-nitrile solvent mol-ecule. The [Rb(18-crown-6)]2[P2S6] unit is completed by inversion symmetry. Its Rb(+) ion is situated near the centre of the macrocyclic cavity, but is displaced by 0.8972 (1) Å from the O atoms of the crown in the direction of the [P2S6](2-) moiety. The overall coordination number of the cation is eight, defined by the six crown ether O atoms and by two terminal S atoms of the [P2S6](2-) anion. The hexa-thio-metadiphosphate anion is built up from two tetra-hedral PS4 units joined together by a common edge. The crystal structure is characterized by alternating layers of [Rb(18-crown-6)]2[P2S6] and aceto-nitrile solvent mol-ecules stacked along [010].

  5. Liquid-chromatographic assay of urinary vanillylmandelic acid and homovanillic acid, with clean-up by on-column injection of acetonitrile or methanol. (United States)

    Kodama, K; Yamanaka, K; Nakata, T; Aoyama, M


    To separately measure vanillylmandelic acid (VMA) and homovanillic acid (HVA) in urine, the sample is diluted 10-fold with 50 mmol/L phosphoric acid, then exactly 5 microL is injected directly onto a 50 X 4.6 mm column of Nucleosil 3C18. Samples can be injected at 5-min intervals because all peaks after these compounds of interest are washed away. VMA is eluted from the column after 2.8 min with 50 mmol/L phosphate buffer, pH 2.2, and measured by electrochemical detection. All peaks eluting after VMA are washed away together, by injection of 50 microL of acetonitrile onto the column. HVA is eluted from the column after 3.3 min with a 100/10 (by vol) mixture of the phosphate buffer and acetonitrile. All later-eluting peaks are washed away together, by injection of 50 microL of methanol onto the column. Analytical recoveries of VMA and HVA were 98.5% and 100.6%, respectively; the CVs for various concentrations of either in urine were about 3%.

  6. Atomistic simulations of a solid/liquid interface: a combined force field and first principles approach to the structure and dynamics of acetonitrile near an anatase surface

    Energy Technology Data Exchange (ETDEWEB)

    Schiffmann, Florian; Hutter, Juerg; VandeVondele, Joost [Physical Chemistry Institute, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich (Switzerland)


    The acetonitrile/anatase(101) interface can be considered a prototypical interface between an oxide and a polar aprotic liquid, and is common in dye sensitized solar cells. Using first principles molecular dynamics simulations of a slab of TiO{sub 2} in contact with neat acetonitrile (MeCN), the liquid structure near this interface has been characterized. Furthermore, in order to investigate properties that require extensive sampling, a classical force field to describe the MeCN/TiO{sub 2} interaction has been optimized, and we show that this force field accurately describes the structure near the interface. We find a surprisingly strong interaction of MeCN with TiO{sub 2}, which leads to an ordered first MeCN layer displaying a significantly enhanced molecular dipole. The strong dipolar interactions between solvent molecules lead to pronounced layering further away from the interface, each successive layer having an alternate orientation of the molecular dipoles. At least seven distinct solvent layers (approximately 12 A) can be discerned in the orientational distribution function. The observed structure also strongly suppresses diffusion parallel to the interface in the first nanometer of the liquid. These results show that the properties of the liquid near the interface differ from those in the bulk, which suggests that solvation near the interface will be distinctly different from solvation in the bulk.

  7. Conductometric Studies of Thermodynamics of Complexation of Co2+, Ni2+, Cu2+, and Zn2+ Cations with Aza-18-crown-6 in Binary Acetonitrile-Methanol Mixtures

    Directory of Open Access Journals (Sweden)

    Mehdi Taghdiri


    Full Text Available The complexation reactions between aza-18-crown-6 (A18C6 and Co2+, Ni2+, Cu2+, and Zn2+ ions were studied conductometrically in different acetonitrile-methanol mixtures at various temperatures. The formation constants of the resulting 1 : 1 complexes were calculated from the computer fitting of the molar conductance-mole ratio data at different temperatures. Selectivity of A18C6 for Co2+, Ni2+, Cu2+, and Zn2+ cations is sensitive to the solvent composition. At 20°C and in acetonitrile solvent, the stability of the resulting complexes varied in the order but the order was reversed byadding 20% methanol. The enthalpy and entropy changes of the complexation reactions were evaluated from the temperature dependence of formation constants. It was found that the stability of the resulting complexes decreased with increasing methanol in the solvent mixture. The TΔS° versus ΔH° plot of thermodynamic data obtained shows a fairly good linear correlation indicating the existence of enthalpy-entropy compensation in the complexation reactions. In addition, binding energies of Ni2+, Cu2+, and Zn2+ complexes with A18C6 were calculated at B3LYP/6-31G level of theory.

  8. Diaqua-μ3-oxido-hexakis(μ2-trichloroacetato-κ2O:O′(trichloroacetato-κOtrichromium(III acetonitrile trisolvate

    Directory of Open Access Journals (Sweden)

    Seik Weng Ng


    Full Text Available In the crystal structure of the title compound, [Cr3(C2Cl3O27O(H2O2]·3CH3CN, the trinuclear [Cr3O(H2O2(Cl3CCO27] molecule has an oxide O atom that is connected to one monodentate trichloroacetate-coordinated and two water-coordinated CrIII atoms, the three metal atoms forming the points of an equilateral triangle. Each of the six remaining carboxylate groups bridges a Cr–O–Cr fragment. The cluster interacts with the three solvent molecules through water–acetonitrile O—H...N hydrogen bonds. Adjacent clusters are linked by a water–carboxylate O—H...O hydrogen bond to give a helical chain. One of the CCl3 groups was found to be disordered over two positions, with the major component having a site-occupancy factor of 0.64 (1.

  9. [A Simultaneous Determination Method with Acetonitrile-n-Hexane Partitioning and Solid-Phase Extraction for Pesticide Residues in Livestock and Marine Products by GC-MS]. (United States)

    Yoshizaki, Mayuko; Kobayashi, Yukari; Shimizu, Masanori; Maruyama, Kouichi


    A simultaneous determination method was examined for 312 pesticides (including isomers) in muscle of livestock and marine products by GC-MS. The pesticide residues extracted from samples with acetone and n-hexane were purified by acetonitrile-n-hexane partitioning, and C18 and SAX/PSA solid-phase extraction without using GPC. Matrix components such as cholesterol were effectively removed. In recovery tests performed by this method using pork, beef, chicken and shrimp, 237-257 pesticides showed recoveries within the range of 70-120% in each sample. Validity was confirmed for 214 of the target pesticides by means of a validation test using pork. In comparison with the Japanese official method using GPC, the treatment time of samples and the quantity of solvent were reduced substantially.

  10. One-pot Reductive Amination of Carbonyl Compounds with NaBH₄-B(OSO₃H)₃/SiO₂ in Acetonitrile and in Solvent-free Condition

    Indian Academy of Sciences (India)



    An efficient one-pot procedure for the direct reductive amination of aldehyde and ketones was achieved in the presence of sodium borohydride by using B(OSO₃H)₃/SiO₂(SBSA) as the reusable solid catalyst in acetonitrile and solvent-free conditions. Both aromatic and aliphatic aldehyde reacted well to give the corresponding amines in excellent yields. All the products are known and well-characterized. The catalyst is recoverable and could be easily recycled by filtration and reused several times without any significant loss of its activity. SBSA acts as a dual Brønsted/Lewis acid that is an air-stable and cost-effective solid acid.

  11. Influence of activated carbon porosity and surface oxygen functionalities' presence on adsorption of acetonitrile as a simple polar volatile organic compound. (United States)

    Furmaniak, Sylwester


    Based on series of porous carbon models, systematic Monte Carlo studies on the adsorption of acetonitrile (as a simple representative of polar volatile organic compounds) were performed. The influence of porosity and chemical composition of the carbon surface on CH3CN adsorption was studied and it was shown that both the factors influenced the adsorption mechanism. A decrease in the pore size and the introduction of oxygen surface groups led to a rise in adsorption energy and to an increase in the filling of accessible volume in the low-pressure part of the isotherm. However, from a practical point of view, it is easier to increase the adsorption by introducing polar groups on the carbon surface than by modifying the porosity.

  12. Polyethylene Glycols as Efficient Catalysts for the Oxidation of Xanthine Alkaloids by Ceric Ammonium Nitrate in Acetonitrile: A Kinetic and Mechanistic Approach

    Directory of Open Access Journals (Sweden)

    S. Shylaja


    Full Text Available Kinetics of oxidation of xanthine alkaloids, such as Xanthine (XAN, hypoxanthine (HXAN, caffeine (CAF, theophylline (TPL, and theobromine (TBR, have been studied with ceric ammonium nitrate (CAN using poly ethylene glycols (PEG as catalysts. Reaction obeyed first order kinetics in both [CAN] and [Xanthine alkaloid]. Highly sluggish CAN-xanthine alkaloid reactions (in acetonitrile media even at elevated temperatures are enhanced in presence PEGs (PEG-200, -300, -400, -600. An increase in [PEG] increased the rate of oxidation linearly. This observation coupled with a change in absorption of CAN in presence of PEG, [H–(OCH2–CH2n–O–NH4Ce(NO34(CH3CN] (PEG bound CAN species, is considered to be more reactive than CAN. The mechanism of oxidation in PEG media has been explained by Menger-Portnoy’s enzymatic model.

  13. Nanosolvation by acetonitrile and 18-crown-6 ether induce strongly different effects on the electron-capture induced dissociation of aromatic tripeptide cations in the gas phase

    DEFF Research Database (Denmark)

    MacLot, S.; Rangama, J.; Nielsen, Steen Brøndsted;


    , acetonitrile and 18-crown-6 ether (CE), to these tripeptide cations on the relative probabilities of their main fragmentation channels (H loss, NH3 loss and N — Cα bond cleavage) after electron capture from sodium atoms. First, we recorded the spectra of bare peptide ions, and found that N — Cα bond cleavage......-terminal ammonium group. Besides, this experimental result is consistent with our DFT calculations, which suggest a lower abundance of N terminally-protonated [KWK+2H]2+(CE)2 compared to bare tripeptide cations. Extracting the H-loss contribution from ECID data had never been done for tripeptides nanosolvated by CE....... This allowed us to observe the enhancement of H loss from KWK and KYK nanosolvated by two CE, but surprisingly, not by one. This peculiar behavior might be due to H transfer from the reduced radical NH3 group to CE, followed by loss of the [CE+H] radical....

  14. Isomeric [RuCl2(dmso)2(indazole)2] complexes: ruthenium(II)-mediated coupling reaction of acetonitrile with 1H-indazole. (United States)

    Reisner, Erwin; Arion, Vladimir B; Rufińska, Anna; Chiorescu, Ion; Schmid, Wolfgang F; Keppler, Bernhard K


    Reaction of the antitumor complex trans-[Ru(III)Cl4(Hind)2]- (Hind = indazole) with an excess of dimethyl sulfoxide (dmso) in acetone afforded the complex trans,trans,trans-[Ru(II)Cl2(dmso)2(Hind)2] (1). Two other isomeric compounds trans,cis,cis-[Ru(II)Cl2(dmso)2(Hind)2] (2) and cis,cis,cis-[Ru(II)Cl2(dmso)2(Hind)2] (3) have been obtained on refluxing cis-[Ru(II)Cl(2)(dmso)(4)] with 2 equiv. of indazole in ethanol and methanol, respectively. Isomers 1 and 2 react with acetonitrile yielding the complexes trans-[Ru(II)Cl2(dmso)(Hind){HN=C(Me)ind}].CH3CN (4.CH3CN) and trans,cis-[Ru(II)Cl2(dmso)2{HN=C(Me)ind}].H2O (5.H2O), respectively, containing a cyclic amidine ligand resulting from insertion of the acetonitrile C triple bond N group in the N1-H bond of the N2-coordinated indazole ligand in the nomenclature used for 1H-indazole. These are the first examples of the metal-assisted iminoacylation of indazole. The products isolated have been characterized by elemental analysis, IR spectroscopy, UV-vis spectroscopy, electrospray mass-spectrometry, thermogravimetry, differential scanning calorimetry, 1H NMR spectroscopy, and solid-state 13C CP MAS NMR spectroscopy. The isomeric structures of 1-3 and the presence of a chelating amidine ligand in 4 and 5 have been confirmed by X-ray crystallography. The electrochemical behavior of 1-5 and the formation of 5 have been studied by cyclic voltammetry.

  15. (Acetonitrile{2-[bis(pyridin-2-ylmethyl-κ2Namino-κN]-N-(2,6-dimethylphenylacetamide-κO}(perchlorato-κOzinc (acetonitrile{2-[bis(pyridin-2-ylmethyl-κ2Namino-κN]-N-(2,6-dimethylphenylacetamide-κO}zinc tris(perchlorate

    Directory of Open Access Journals (Sweden)

    Ove Alexander Høgmoen Åstrand


    Full Text Available In the title salt, [Zn(C22H24N4O(CH3CN][Zn(ClO4(C22H24N4O(CH3CN](ClO43, two differently coordinated zinc cations occur. In the first complex, the metal ion is coordinated by the N,N′,N′′,O-tetradentate acetamide ligand and an acetonitrile N atom, generating an approximate trigonal–bipyramidal coordination geometry, with the O atom in an equatorial site and the acetonitrile N atom in an axial site. In the second complex ion, a perchlorate ion is also bonded to the zinc ion, generating a distorted trans-ZnO2N4 octahedron. Of the uncoordinating perchlorate ions, one lies on a crystallographic twofold axis and one lies close to a twofold axis and has a site occupancy of 0.5. N—H...O and N—H...(O,O hydrogen bonds are observed in the crystal. Disordered solvent molecules occupy about 11% of the unit-cell volume; their contribution to the scattering was removed with the SQUEEZE routine of the PLATON program [Spek (2009. Acta Cryst. D65, 148–155.].

  16. Retention of ionisable compounds on high-performance liquid chromatography XVIII: pH variation in mobile phases containing formic acid, piperazine, tris, boric acid or carbonate as buffering systems and acetonitrile as organic modifier. (United States)

    Subirats, Xavier; Bosch, Elisabeth; Rosés, Martí


    In the present work dissociation constants of commonly used buffering species, formic acid, piperazine, tris(hydroxymethyl)-aminomethane, boric acid and carbonate, have been determined for several acetonitrile-water mixtures. From these pK(a) values a previous model has been successfully evaluated to estimate pH values in acetonitrile-aqueous buffer mobile phases from the aqueous pH and concentration of the above mentioned buffers up to 60% of acetonitrile, and aqueous buffer concentrations between 0.005 (0.001 mol L(-1) for formic acid-formate) and 0.1 mol L(-1). The relationships derived for the presently studied buffers, together with those established for previously considered buffering systems, allow a general prediction of the pH variation of the most commonly used HPLC buffers when the composition of the acetonitrile-water mobile phase changes during the chromatographic process, such as in gradient elution. Thus, they are an interesting tool that can be easily implemented in general retention models to predict retention of acid-base analytes and optimize chromatographic separations.

  17. Structure-retention and mobile phase-retention relationships for reversed-phase high-performance liquid chromatography of several hydroxythioxanthone derivatives in binary acetonitrile-water mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Amiri, Ali Asghar; Hemmateenejad, Bahram; Safavi, Afsaneh; Sharghi, Hashem; Beni, Ali Reza Salimi [Department of Chemistry, Shiraz University, Shiraz (Iran, Islamic Republic of); Shamsipur, Mojtaba [Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of)], E-mail:


    The reversed-phase high-performance liquid chromatographic (RP-HPLC) behavior of some newly synthesized hydroxythioxanthone derivatives using binary acetonitrile-water mixtures as mobile phase has been examined. First, the variation in the retention time of each molecule as a function of mobile phase properties was studied by Kamlet-Taft solvatochromic equations. Then, the influences of molecular structure of the hydroxythioxanthone derivatives on their retention time in various mobile phase mixtures were investigated by quantitative structure-property relationship (QSPR) analysis. Finally, a unified model containing both the molecular structure parameters and mobile phase properties was developed to describe the chromatographic behavior of the systems studied. Among the solvent properties, polarity/polarizability parameter ({pi}{sup *}) and hydrogen-bond basicity ({beta}), and among the solute properties, the most positive local charge (MPC), the sum of positive charges on hydrogen atoms contributing in hydrogen bonding (SPCH) and lipophilicity index (log P) were identified as controlling factors in the RP-HPLC behavior of hydroxythioxanthone derivatives in actonitrile-water binary solvents.

  18. Localization of double bonds in wax esters by high-performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry utilizing the fragmentation of acetonitrile-related adducts. (United States)

    Vrkoslav, Vladimír; Háková, Martina; Pecková, Karolina; Urbanová, Klára; Cvačka, Josef


    Unsaturated wax esters (WEs) provided molecular adducts with C(3)H(5)N ([M + 55](+•)) in APCI sources in the presence of acetonitrile. CID MS/MS of [M + 55](+•) yielded fragments allowing the localization of double bond(s) in the hydrocarbon chains of the WEs. These fragments were formed by a cleavage on each side of the double bond. In methylene-interrupted polyunsaturated WEs, diagnostic fragments related to each double bond were detected; the most abundant were those corresponding to the cleavage of the C-C bond next to the first and the last double bond. To differentiate between those fragments differing in their structure or origin, a simple nomenclature based on α and ω ions has been introduced. Fragmentation of the α-type ions (fragments containing an ester bond) provided information on the occurrence of a double bond in the acid or alcohol part of the WEs. While no significant differences between the spectra of the WEs differing by cis/trans isomerism were found, the isomers were separated chromatographically. A data-dependent HPLC/APCI-MS(2) method for the comprehensive characterization of WEs in their complex mixtures has been developed and applied to natural mixtures of WEs isolated from jojoba oil and beeswax. More than 50 WE molecular species were completely identified, including the information on the acid and alcohol chain length and the position of the double bonds.

  19. Catalytic role of TiO(2) terminal oxygen atoms in liquid-phase photocatalytic reactions: oxidation of aromatic compounds in anhydrous acetonitrile. (United States)

    Montoya, Juan F; Bahnemann, Detlef W; Peral, José; Salvador, Pedro


    On the basis of experiments carried out with controlled amounts of residual oxygen and water, or by using oxygen-isotope-labeled Ti(18) O2 as the photocatalyst, we demonstrate that (18) Os atoms behave as real catalytic species in the photo-oxidation of acetonitrile-dissolved aromatic compounds such as benzene, phenol, and benzaldehyde with TiO2 . The experimental evidence allows a terminal-oxygen indirect electron-transfer (TOIET) mechanism to be proposed, which is a new pathway that involves the trapping of free photogenerated valence-band holes at Os species and their incorporation into the reaction products, with simultaneous generation of oxygen vacancies at the TiO2 surface and their subsequent healing with oxygen atoms from either O2 or H2 O molecules that are dissolved in the liquid phase. According to the TOIET mechanism, the TiO2 surface is not considered to remain stable, but is continuously changing in the course of the photocatalytic reaction, challenging earlier interpretations of TiO2 photocatalytic phenomena.

  20. 乙腈加氢制乙胺的合成过程研究%The Study of Acetonitrile Synthesizing Ethylamine by Hydrogenation under the Help of Catalyst

    Institute of Scientific and Technical Information of China (English)



    以乙腈和氢气为原料,在催化剂和过量氨的作用下催化反应合成乙胺,优化的操作条件为:反应温度140~180℃,反应压力为2.0~2.5 MPa,乙腈的进料量为5.64 g/h,同时考察了Ni-La/γ-Al2 O3复合型催化剂对反应结果的影响,在该催化条件下体系的转化率可达到96.75%,总收率达到96.04%,选择性为99.27%。%Acetonitrile and hydrogen were used as raw materials to synthesizing ethylamine under the function of an excess of ammonia and the catalyst.The optimal operating conditions as follows:temperature was 100~140℃, pressure was 2.0~3.0 MPa, the feedstock rate of ethylamine was 5.64 g/h, Ni-La/γ-Al2 O3 was used as catalyst.The reaction results showed that the conversion rate was 93.16%, the total yield was 92.99%, the selectivity was 98.95%.

  1. Interaction of nickelocene with pentacarbonylchlororhenium and tris(acetonitrile)tricarbonylmolybdenum. Molecular structure of the tetracarbonylchlororhenium dimer and refinement of the determination of the structure of dicarbonyltris(cyclopentadienylnickel)

    Energy Technology Data Exchange (ETDEWEB)

    Pasynskii, A.A.; Shaposhnikova, A.D.; Skripkin, Yu.V.; Zalmanovich, V.R.; Eremenko, I.L.; Antsyshkina, A.S. Bel' skii, V.K.


    The reaction of nickelocene Cp/sub 2/Ni (I) with ClRe(CO)/sub 5/ in toluene gives the corresponding of polynuclear complexes (ClRe(CO)/sub 4/)/sub 2/ (II) and Cp/sub 3/Ni/sub 3/(CO)/sub 2/ (III). Complex III is also produced when nickelocene (I) is reacted with (MeCn)/sub 3/Mo(CO)/sub 3/ in acetonitrile. An x-ray diffraction investigation of complexes II and III has been carried out. Complex II is a dimer; the rhenium atoms, which are separated by a nonbonding Re...Re distance equal to 3.809 (3) A, each have four terminal CO groups. The mean values of the ReClRe and ClReCl angles are 98.6 and 81.4/sup 0/. In complex III the nickel atoms form an equilateral triangle with Ni-Ni-distances equal to 2.387(1) A and NiNiNi angles equal to 60/sup 0/. The Ni-C(Cp)/sub av/ distance is 2.10 A. The molecule has high symmetry corresponding to the C/sub 3h/ group.

  2. Synthesis of Polypyrrole Inverse Opal in [bmim]PF6- Containing Acetonitrile and the Application of the Inverse Opal in Cell Prototype

    Directory of Open Access Journals (Sweden)

    Wei Yan


    Full Text Available Most primary cells use Zn or Li as the anode, a metallic oxide as the cathode, and an acidic or alkaline solution or moist past as the electrolytic solution. In this paper, highly ordered polypyrrole (PPy inverse opals have been successfully synthesized in the acetonitrile solution containing [bmim]PF6. PPy films were prepared under the same experimental conditions. Cyclic voltammograms of the PPy film and the PPy inverse opal in neutral phosphate buffer solution (PBS were recorded. X-ray photoelectron spectroscopy technique was used to investigate the structural surface of the PPy films and the PPy inverse opals. It is found that the PF6- anions kept dedoping from the PPy films during the potential scanning process, resulting in the electrochemical inactivity. Although PF6- anions also kept dedoping from the PPy inverse opals, the PO43- anions from PBS could dope into the inverse opal, explaining why the PPy inverse opals kept their electrochemical activity. An environmental friendly cell prototype was constructed, using the PPy inverse opal as the anode. The electrolytes in both the cathodic and anodic half-cells were neutral PBSs. The open-circuit potential of the cell prototype reached 0.487 V and showed a stable output over several hundred hours.

  3. fac-[1,2-Bis(pyridin-4-ylethane-κN]tricarbonyl(1,10-phenanthroline-κ2N,N′rhenium(I hexafluoridophosphate acetonitrile monosolvate

    Directory of Open Access Journals (Sweden)

    Silvana Guilardi


    Full Text Available The asymmetric unit of the title compound, [Re(C12H8N2(C12H12N2(CO3]PF6.·CH3CN, contains one cation, one hexafluoridophosphate anion and one acetonitrile solvent molecule. The ReI ion is coordinated by two N atoms from the 1,10-phenanthroline ligand and one N atom from the 1,2-bis(pyridin-4-ylethane ligand [mean Re—N = 2.191 (15 Å] and by three carbonyl ligands [mean Re—C = 1.926 (3 Å] in a distorted octahedral geometry. The electrostatic forces and weak C—H...F(O hydrogen bonds pack cations and anions into the crystal with voids of 82 Å3, which are filled by solvent molecules. The crystal packing exhibits short intermolecular O...O distance of 2.795 (5 Å between two cations related by inversion.

  4. Non-ideality in Born-free energy of solvation in alcohol-water and dimethylsulfoxide-acetonitrile mixtures: Solvent size ratio and ion size dependence

    Indian Academy of Sciences (India)

    Hemant K Kashyap; Ranjit Biswas


    Recent extension of mean spherical approximation (MSA) for electrolyte solution has been employed to investigate the non-ideality in Born-free energy of solvation of a rigid, mono-positive ion in binary dipolar mixtures of associating (ethanol-water) and non-associating (dimethylsulfoxide-acetonitrile) solvents. In addition to the dipole moments, the solvent size ratio and ion size have been treated in a consistent manner in this extended MSA theory for the first time. The solvent-solvent size ratio is found to play an important role in determining the non-ideality in these binary mixtures. Smaller ions such as Li+ and Na+ show stronger non-ideality in such mixtures compared to bigger ions (for example, Cs+ and Bu4N+). The partial solvent polarization densities around smaller ions in tertiary butanol (TBA)-water mixture is found to be very different from that in other alcohol-water mixtures as well as to that for larger ions in aqueous solutions of TBA. Non-ideality is weaker in mixtures consisting of solvent species possessing nearly equal diameters and dipole moments and is reflected in the mole fraction dependent partial solvent polarization densities.

  5. Hydride, hydrogen, proton, and electron affinities of imines and their reaction intermediates in acetonitrile and construction of thermodynamic characteristic graphs (TCGs) of imines as a "molecule ID card". (United States)

    Zhu, Xiao-Qing; Liu, Qiao-Yun; Chen, Qiang; Mei, Lian-Rui


    A series of 61 imines with various typical structures were synthesized, and the thermodynamic affinities (defined as enthalpy changes or redox potentials in this work) of the imines to abstract hydride anions, hydrogen atoms, and electrons, the thermodynamic affinities of the radical anions of the imines to abstract hydrogen atoms and protons, and the thermodynamic affinities of the hydrogen adducts of the imines to abstract electrons in acetonitrile were determined by using titration calorimetry and electrochemical methods. The pure heterolytic and homolytic dissociation energies of the C=N pi-bond in the imines were estimated. The polarity of the C=N double bond in the imines was examined using a linear free-energy relationship. The idea of a thermodynamic characteristic graph (TCG) of imines as an efficient "Molecule ID Card" was introduced. The TCG can be used to quantitatively diagnose and predict the characteristic chemical properties of imines and their various reaction intermediates as well as the reduction mechanism of the imines. The information disclosed in this work could not only supply a gap of thermodynamics for the chemistry of imines but also strongly promote the fast development of the applications of imines.

  6. High-throughput salting-out-assisted homogeneous liquid-liquid extraction with acetonitrile for determination of baicalin in rat plasma with high-performance liquid chromatography. (United States)

    Li, Tingting; Zhang, Lei; Tong, Ling; Liao, Qiongfeng


    Baicalin is the main indicator for qualitative and quantitative analysis of Scutellaria baicalensis Georgi and its prescription in vivo and in vitro. Owing to its insolubility and instability, the analysis of baicalin in biological samples is analytically challenging. Although there have been many pharmacokinetic or metabolism studies on baicalin, the current reported sample pretreatment methods are not the optimal choice with regard to absolute recovery and operation procedure. Here we report a high-throughput salting-out-assisted homogeneous liquid-liquid extraction method with acetonitrile and ammonium sulfate. Eight kinds of commonly used salts, preferred salt concentration and auxiliary solvents were investigated. The extraction efficiency in the presence of ammonium salt and auxiliary solvent (methanol) in comparison to that from the salt-free aqueous increased to above 90%. The performance of the developed pretreatment method was further evaluated through testing specificity, linearity, precision, accuracy, extraction recovery and stability. In particular, the stability investigation results proved that the operation at low temperature would no longer necessary be for salting-out-assisted homogeneous liquid-liquid extraction compared with protein precipitation, and the pretreatment method would be valuable if the compounds were unstable within matrices.

  7. Application of the Kirkwood-Buff theory of solutions to acetonitrile + amide binary mixtures by using inversion procedure and regular solution theory

    Indian Academy of Sciences (India)

    Anil Kumar Nain


    The Kirkwood-Buff (K-B) integrals play an important role in characterizing the intermolecular interactions in liquid mixtures. These are represented by the K-B parameters, AA, BB, and AB, which reflect correlation between like-like and like-unlike species in the mixture. The K-B integrals of binary mixtures of acetonitrile (ACN) with formamide (FA), N,N-dimethylformamide (DMF), N-methylacetamide (NMA) and N,N-dimethylacetamide (DMA) at 298.15 K and at atmospheric pressure have been computed from the experimental data of ultrasonic speed and density. We have used the similar inverse procedure (as proposed by Ben-Naim) to compute the K-B Parameters of the mixtures, in which thermodynamic information on mixtures such as partial molar volumes, isothermal compressibility, and experimental data of partial vapour pressures are used. A new route has been incorporated by using regular solution theory in the computation of excess free energy for obtaining the partial vapour pressures of binary liquid mixtures. The low values of excess entropy ( ≈ 0) obtained for these mixtures indicate the applicability of regular solution theory to these mixtures. The results obtained regarding intermolecular interaction in all the four mixtures under study from this new procedure are in good agreement with those obtained from the trends exhibited by the excess functions of these mixtures.

  8. Greening pharmaceutical applications of liquid chromatography through using propylene carbonate-ethanol mixtures instead of acetonitrile as organic modifier in the mobile phases. (United States)

    Tache, Florentin; Udrescu, Stefan; Albu, Florin; Micăle, Florina; Medvedovici, Andrei


    Substitution of acetonitrile (ACN) as organic modifier in mobile phases for liquid chromatography by mixtures of propylene carbonate (PC) and ethanol (EtOH) may be considered a greener approach for pharmaceutical applications. Such a replacement is achievable without any major compromise in terms of elution order, chromatographic retention, efficiency and peak symmetry. This has been equally demonstrated for reverse phase (RP), ion pair formation (IP) and hydrophilic interaction liquid chromatography (HILIC) separation modes. The impact on the sensitivity induced by the replacement between these organic solvents is discussed for UV-vis and mass spectrometric detection. A comparison between Van Deemter plots obtained under elution conditions based on ACN and PC/EtOH is presented. The alternative elution modes were also compared in terms of thermodynamic parameters, such as standard enthalpy (ΔH⁰) and entropic contributions to the partition between the mobile and the stationary phases, for some model compounds. Van't Hoff plots demonstrated that differences between the thermodynamic parameters are minor when shifting from ACN/water to PC/EtOH/water elution on an octadecyl chemically modified silicagel stationary phase. As long as large volume injection (LVI) of diluents non-miscible with the mobile phase is a recently developed topic having a high potential of greening the sample preparation procedures through elimination of the solvent evaporation stage, this feature was also assessed in the case of ACN replacement by PC/EtOH.

  9. Dichlorido(2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline-κ2N,N′mercury(II acetonitrile hemisolvate

    Directory of Open Access Journals (Sweden)

    Vahid Amani


    Full Text Available The asymmetric unit of the title compound, [HgCl2(C26H20N2]·0.5CH3CN, contains two crystallographically independent [HgCl2(C26H20N2] molecules and one acetonitrile solvent molecule. The HgII atoms are four-coordinated in distorted tetrahedral configurations by two N atoms from 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline ligands and two Cl atoms. The ligand ring systems are not planar. The phenyl rings are oriented at dihedral angles of 74.61 (3 and 66.00 (3° in the two molecules. In the crystal structure, π–π contacts between phenanthroline rings [centroid–centroid distances = 3.809 (1, 3.686 (1, 3.986 (1, 3.877 (1, 3.697 (1, 3.789 (1, 3.745 (1, 3.797 (1 and 3.638 (1 Å] may stabilize the structure.

  10. Increasing the energy density of the non-aqueous vanadium redox flow battery with the acetonitrile-1,3-dioxolane-dimethyl sulfoxide solvent mixture (United States)

    Herr, T.; Fischer, P.; Tübke, J.; Pinkwart, K.; Elsner, P.


    Different solvent mixtures were investigated for non-aqueous vanadium acetylacetonate (V(acac)3) redox flow batteries with tetrabutylammonium hexafluorophosphate as the supporting electrolyte. The aim of this study was to increase the energy density of the non-aqueous redox flow battery. A mixture of acetonitrile, dimethyl sulfoxide and 1-3-dioxolane nearly doubles the solubility of the active species. The proposed electrolyte system was characterized by Raman and FT-IR spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy and charge-discharge set-up. Spectroscopic methods were applied to understand the interactions between the solvents used and their impact on the solubility. The potential difference between oxidation and reduction of V(acac)3 measured by cyclic voltammetry was about 2.2 V. Impedance spectroscopy showed an electrolyte resistance of about 2400 Ω cm2. Experiments in a charge-discharge test cell achieved coulombic and energy efficiencies of ∼95% and ∼27% respectively. The highest discharge power density was 0.25 mW cm-2.

  11. Conductance Studies on Complex Formation between c-Methylcalix[4]resorcinarene and Titanium (III in Acetonitrile-H2O Binary Solutions

    Directory of Open Access Journals (Sweden)

    Naghmeh Saadati


    Full Text Available Calixresorcinarenes have proved to be unique molecules for molecular recognition via hydrogen bonding, hydrophobic and ionic interactions with suitable substrates such as cations. The study of the interactions involved in the complexation of different cations with calixresorcinarenes in solvent mixtures is important for a better understanding of the mechanism of biological transport, molecular recognition, and other analytical applications. This article summarizes different aspects of the complexes of the Ti3+ metal cation with c-methylcalix[4]resorcinarene (CMCR as studied by conductometry in acetonitrile (AN–water (H2O binary mixtures at different temperatures. Conductance data show that the metal cation/ligand (ML stoichiometry of the complexes in solution is 1:1 in all cases. Non-linear behaviour was observed for the variation of logKf of the complexes vs. the composition of the binary solvent mixtures. Selectivity of CMCR for the Ti3+ cation is sensitive to solvent composition; in some cases and at certain compositions of the mixed solvent systems, the selectivity order is changed. Values of thermodynamic parameters (, for formation of the CMCR–Ti3+ complexes in AN–H2O binary systems were obtained from the temperature dependence of stability constants, and the results show that the thermodynamics of complexation reactions are affected by the nature and composition of the mixed solvents.

  12. Direct observation of metal nanoparticles as heterogeneous nuclei for the condensation of supersaturated organic vapors: nucleation of size-selected aluminum nanoparticles in acetonitrile and n-hexane vapors. (United States)

    Abdelsayed, Victor; El-Shall, M Samy


    This work reports the direct observation and separation of size-selected aluminum nanoparticles acting as heterogeneous nuclei for the condensation of supersaturated vapors of both polar and nonpolar molecules. In the experiment, we study the condensation of supersaturated acetonitrile and n-hexane vapors on charged and neutral Al nanoparticles by activation of the metal nanoparticles to act as heterogeneous nuclei for the condensation of the organic vapor. Aluminum seed nanoparticles with diameters of 1 and 2 nm are capable of acting as heterogeneous nuclei for the condensation of supersaturated acetonitrile and hexane vapors. The comparison between the Kelvin and Fletcher diameters indicates that for the heterogeneous nucleation of both acetonitrile and hexane vapors, particles are activated at significantly smaller sizes than predicted by the Kelvin equation. The activation of the Al nanoparticles occurs at nearly 40% and 65% of the onset of homogeneous nucleation of acetonitrile and hexane supersaturated vapors, respectively. The lower activation of the charged Al nanoparticles in acetonitrile vapor is due to the charge-dipole interaction which results in rapid condensation of the highly polar acetonitrile molecules on the charged Al nanoparticles. The charge-dipole interaction decreases with increasing the size of the Al nanoparticles and therefore at low supersaturations, most of the heterogeneous nucleation events are occurring on neutral nanoparticles. No sign effect has been observed for the condensation of the organic vapors on the positively and negatively charged Al nanoparticles. The present approach of generating metal nanoparticles by pulsed laser vaporization within a supersaturated organic vapor allows for efficient separation between nucleation and growth of the metal nanoparticles and, consequently controls the average particle size, particle density, and particle size distribution within the liquid droplets of the condensing vapor. Strong

  13. Cluster-continuum quasichemical theory calculation of the lithium ion solvation in water, acetonitrile and dimethyl sulfoxide: an absolute single-ion solvation free energy scale. (United States)

    Carvalho, Nathalia F; Pliego, Josefredo R


    Absolute single-ion solvation free energy is a very useful property for understanding solution phase chemistry. The real solvation free energy of an ion depends on its interaction with the solvent molecules and on the net potential inside the solute cavity. The tetraphenyl arsonium-tetraphenyl borate (TATB) assumption as well as the cluster-continuum quasichemical theory (CC-QCT) approach for Li(+) solvation allows access to a solvation scale excluding the net potential. We have determined this free energy scale investigating the solvation of the lithium ion in water (H2O), acetonitrile (CH3CN) and dimethyl sulfoxide (DMSO) solvents via the CC-QCT approach. Our calculations at the MP2 and MP4 levels with basis sets up to the QZVPP+diff quality, and including solvation of the clusters and solvent molecules by the dielectric continuum SMD method, predict the solvation free energy of Li(+) as -116.1, -120.6 and -123.6 kcal mol(-1) in H2O, CH3CN and DMSO solvents, respectively (1 mol L(-1) standard state). These values are compatible with the solvation free energy of the proton of -253.4, -253.2 and -261.1 kcal mol(-1) in H2O, CH3CN and DMSO solvents, respectively. Deviations from the experimental TATB scale are only 1.3 kcal mol(-1) in H2O and 1.8 kcal mol(-1) in DMSO solvents. However, in the case of CH3CN, the deviation reaches a value of 9.2 kcal mol(-1). The present study suggests that the experimental TATB scale is inconsistent for CH3CN. A total of 125 values of the solvation free energy of ions in these three solvents were obtained. These new data should be useful for the development of theoretical solvation models.

  14. The mixed-valent copper thiolate complex hexakis{μ3-2-[(1,3-dimethylimidazolideneamino]benzenethiolato}dicopper(IItetracopper(I bis(hexafluoridophosphate acetonitrile disolvate dichloromethane disolvate

    Directory of Open Access Journals (Sweden)

    Adam Neuba


    Full Text Available The molecular structure of the title compound, [Cu4ICu2II(C11H14N3S6](PF62·2CH3CN·2CH2Cl2, shows a mixed-valent copper(I/II thiolate complex with a distorted tetrahedral coordination of the CuI and CuII cations by one guanidine N atom and three S atoms each. Characteristic features of the Cu6S6 skeleton are a total of six chemically identical μ3-thiolate bridges and almost planar Cu2S2 units with a maximum deviation of 0.110 (1 Å from the best plane. Each Cu2S2 unit then shares common Cu–S edges with a neighbouring unit; the enclosed dihedral angle is 60.14 (2°. The geometric centre of the Cu6S6 cation lies on a crystallographic inversion centre. Cu—S bond lengths range from 2.294 (1 to 2.457 (1 Å, Cu—N bond lengths from 2.005 (3 to 2.018 (3 Å and the non-bonding Cu...Cu distances from 2.5743 (7 to 2.5892 (6 Å. C—H...F hydrogen-bond interactions occur between the PF6− anion and the complex molecule and between the PF6− anion and the acetonitrile solvent molecule.

  15. Effects of ionic liquid [bmim][PF6] on absorption spectra and reaction kinetics of the duroquinone triplet state in acetonitrile. (United States)

    Zhu, Guanglai; Wu, Guozhong; Sha, Maolin; Long, Dewu; Yao, Side


    The transient absorption spectra and photoinduced electron-transfer process of duroquinone (DQ) in mixed binary solutions of ionic liquid (IL) [bmim][PF6] and acetonitrile (MeCN) have been investigated by laser photolysis at an excitation wavelength of 355 nm. A spectral blue shift of 3DQ* was observed in the IL/MeCN mixtures compared to MeCN. At lower VIL(volume fraction of IL), the interaction between DQ and the solvent is dominant, and the decay rate constant (kobs) of 3DQ* increases steadily with the increasing of VIL; to the contrary, at higher VIL, the network structures due to the hydrogen bond and viscosity are dominant, and the decay rate constant decreases obviously with increasing VIL. A critical point (turnover) was observed at VIL = approximately 0.30. The dependence of the observed growth rate (kgr) of the photoinduced electron-transfer (PET) products on VIL is complex and shows a special change; kgr first decreases with increasing VIL, then increases, and finally decreases slowly with further increasing of VIL. It is speculated that the PET process in the mixture can be affected by factors including the local structure and the reorganization energy of the solvent and salt and cage effects. The change of local structure of [bmim][PF6]/MeCN is supported by following the steady-state fluorescence behavior of the mixture, in combination with the molecular dynamics simulation of the thermodynamic property. The results revealed that the degree of self-aggregation of monomeric cations (bmim+) to associated forms increases with increasing VIL. This is in good agreement with the laser photolysis results for the same solutions.

  16. A salting out-acetonitrile homogeneous extraction coupled with gas chromatography-mass spectrometry method for the simultaneous determination of thirteen N-nitrosamines in skin care cosmetics. (United States)

    Dong, Hao; Guo, Xindong; Xian, Yanping; Luo, Haiying; Wang, Bin; Wu, Yuluan


    A sensitive gas chromatography-mass spectrometry method was established for the simultaneous determination of thirteen N-nitrosamines (NAs) in skin care cosmetics. The cosmetics samples were firstly dispersed by water and subsequently extracted and purified using salting out-acetonitrile homogeneous extraction method. Finally, the extracting solution was concentrated by slow nitrogen gas blowing. All of the samples were separated by INNOWAX capillary chromatographic column, and detected by selected ion monitoring (SIM) mode of gas chromatography-mass spectrometry (GC-MS) and quantified by isotope internal standard method. The method was validated for linearity and range, accuracy, precision and sensitivity. Under the optimized condition, the calibration curves were linear over the selected concentration ranges of 2-500μg/L for all the thirteen analytes, with calculated coefficients of determination (R(2)) of greater than 0.996. The limits of detection (LODs) and the limits of quantitation (LOQs) of the method were 3-15μg/kg and 10-50μg/kg, respectively. Recoveries were calculated at three levels of concentration spiked in two kinds of cosmetics (skin care cream and water). The values were found between 93.8% and 121.0% with relative standard deviation (RSD) values of 2.5-7.2% for intra-day precision (n=6) and 3.3-6.7% for inter-day precision (n=5). The method was successfully applied to analyze twenty-two cosmetics samples and N-nitrosodimethylamine (NDMA) was detected in one sample with the concentration of 207μg/kg.

  17. Synthesis and Crystal Structure of cis-[1,2-Bis(phenyl-thiomethyl)benzene]dichloroplatinum( Ⅱ )·0.5acetonitrile

    Institute of Scientific and Technical Information of China (English)

    郑艳; 李建荣; 邹如强; 陈久桐; 卜显和


    The title complex was prepared from the reaction of 1,2-bis(phenylthiomethyl)-benzene L with K2PtCl4 at room temperature and its structure has been determined by single-crystal X-ray diffraction. There exist two independent cis-[1,2-bis(phenylthiomethyl)benzene]dichloroplatinum(Ⅱ) [PtCl2L] molecules without significant structural difference and a molecule of acetonitrile in one crystallographic asymmetric unit. Crystallographic data: triclinic, space group P1-, a = 11.010(3), b = 12.080(3), c = 16.095(4)(A), α = 94.728(5),β = 90.129(5), γ = 99.274(5)°,C2oH18Cl2NPtS2@0.5CH3CN, Mr = 608.98, V = 2105(1) (A)3, Z = 4, Dc = 1.921 g/cm3, μ(Mo-Kα) =7.122 mm-1, F(000) = 1172, R = 0.0503 and wR = 0.0848 for 3929 observed reflections with Ⅰ>2σ(Ⅰ). The title complex is a neutral molecule in which the central Pt(Ⅱ) ion is four-coordinated with two S-donors of the ligand and two Cl- anions, forming a distorted square planar geometry. In the crystal, there exist two kinds of molecular packing patterns. One [PtCl2L] molecule is connected to the other one through the weak interactions of Pt…Pt, Pt…S and Pt…C1, forming a supramolecular quasi-dimer. The other one complex molecule is connected with the CH3CN molecule by weak Cl…N interaction.

  18. Dispersive liquid-liquid microextraction for the determination of phenols by acetonitrile stacking coupled with sweeping-micellar electrokinetic chromatography with large-volume injection. (United States)

    He, Hui; Liu, Shuhui; Meng, Zhaofu; Hu, Shibing


    The current routes to couple dispersive liquid-liquid microextraction (DLLME) with capillary electrophoresis (CE) are evaporation of water immiscible extractants and backextraction of analytes. The former is not applicable to extractants with high boiling points, the latter being effective only for acidic or basic analytes, both of which limit the further application of DLLME-CE. In this study, with 1-octanol as a model DLLME extractant and six phenols as model analytes, a novel method based on acetonitrile stacking and sweeping is proposed to accomplish large-volume injection of 1-octanol diluted with a solvent-saline mixture before micellar electrokinetic chromatography. Brij-35 and β-cyclodextrin were employed as pseudostationary phases for sweeping and also for improving the compatibility of sample zone and aqueous running buffer. A short solvent-saline plug was used to offset the adverse effect of the water immiscible extractant on focusing efficiency. The key parameters affecting separation and concentration were systematically optimized; the effect of Brij-35 and 1-octanol on focusing mechanism was discussed. Under the optimized conditions, with ∼ 30-fold concentration enrichment by DLLME, the diluted extractant (8×) was then injected into the capillary with a length of 21 cm (42% of the total length), which yielded the overall improvements in sensitivity of 170-460. Limits of detection and qualification ranged from 0.2 to 1.0 ng/mL and 1.0 to 3.4 g/mL, respectively. Acceptable repeatability lower than 3.0% for migration time and 9.0% for peak areas were obtained. The developed method was successfully applied for analysis of the phenol pollutants in real water samples.

  19. Identification and separation of the organic compounds in coal-gasification condensate waters. [5,5 dimethyl hydantoin, dihydroxy benzenes, acetonitrile

    Energy Technology Data Exchange (ETDEWEB)

    Mohr, D.H. Jr.; King, C.J.


    A substantial fraction of the organic solutes in condensate waters from low-temperature coal-gasification processes are not identified by commonly employed analytical techniques, have low distriution coefficients (K/sub C/) into diisopropyl ether (DIPE) or methyl isobutyl ketone (MIBK), and are resistant to biological oxidation. These compounds represent an important wastewater-treatment problem. Analytical techniques were developed to detect these polar compounds, and the liquid-liquid phase equilibria were measured with several solvents. A high-performance liquid - chromatography (HPLC) technique was employed to analyze four condensate-water samples from a slagging fixed-bed gasifier. A novel sample-preparation technique, consisting of an azeotropic distillation with isopropanol, allowed identification of compounds in the HPLC eluant by combined gas chromatography and mass spectrometry. 5,5-dimethyl hydantoin and related compounds were identified in condensate waters for the first time, and they account for 1 to 6% of the chemical oxygen demand (COD). Dimethyl hydatoin has a K/sub D/ of 2.6 into tributyl phosphate (TBP) and much lower K/sub D/ values into six other solvents. It is also resistant to biological oxidation. Phenols (59 to 76% of the COD), dihydroxy benzenes (0.02 to 9.5% of the COD), and methanol, acetonitrile, and acetone (15% of the COD in one sample) were also detected. Extraction with MIBK removed about 90% of the COD. MIBK has much higher K/sub D/ values than DIPE for dihydroxy benzenes. Chemical reactions occurred during storage of condensate-water samples. The reaction products had low K/sub D/ values into MIBK. About 10% of the COD had a K/sub D/ of nearly zero into MIBK. These compounds were not extracted by MIBK over a wide range of pH. 73 references, 6 figures, 35 tables.

  20. Active and Recyclable Catalytic Synthesis of Indoles by Reductive Cyclization of 2-(2-Nitroaryl)acetonitriles in the Presence of Co-Rh Heterobimetallic Nanoparticles with Atmospheric Hydrogen under Mild Conditions. (United States)

    Choi, Isaac; Chung, Hyunho; Park, Jang Won; Chung, Young Keun


    A cobalt-rhodium heterobimetallic nanoparticle-catalyzed reductive cyclization of 2-(2-nitroaryl)acetonitriles to indoles has been achieved. The tandem reaction proceeds without any additives under the mild conditions (1 atm H2 and 25 °C). This procedure could be scaled up to the gram scale. The catalytic system is significantly stable under these reaction conditions and could be reused more than ten times without loss of catalytic activity.

  1. Electrochemistry in Near-Critical and Supercritical Fluids. 8. Methyl Viologen, Decamethylferrocene, Os(bpy)3(2+) and Ferrocene in Acetonitrile and the Effect of Pressure on Diffusion Coefficients under Supercritical Conditions (United States)


    Electroanalytical Chemistry The Univeristy of Texas at Austin _rCTEDepartment of Chemistry OT1 isAustin, Texas 78712 0 C T July 20, 1989 Reproduction in whole or...correlated to values calculated by the Stokes- Einstein relation.(’ : (end of abstract) -I--- IM~t I I Submitted to the Journal of Electroanalytical ... Chemistry June 1989 2 INTRODUCTION We report here further studies of electrode reactions in near-critical and supercritical acetonitrile (MeCN). We

  2. Multiresidue pesticide analysis of ginseng powders using acetonitrile- or acetone-based extraction, solid-phase extraction cleanup, and gas chromatography-mass spectrometry/selective ion monitoring (GC-MS/SIM) or -tandem mass spectrometry (GC-MS/MS). (United States)

    Wong, Jon W; Zhang, Kai; Tech, Katherine; Hayward, Douglas G; Krynitsky, Alexander J; Cassias, Irene; Schenck, Frank J; Banerjee, Kaushik; Dasgupta, Soma; Brown, Don


    A multiresidue method for the analysis of 168 pesticides in dried powdered ginseng has been developed using acetonitrile or acetone mixture (acetone/cyclohexane/ethyl acetate, 2:1:1 v/v/v) extraction, solid-phase extraction (SPE) cleanup with octyl-bonded silica (C(8)), graphitized carbon black/primary-secondary amine (GCB/PSA) sorbents and toluene, and capillary gas chromatography-mass spectrometry/selective ion monitoring (GC-MS/SIM) or -tandem mass spectrometry (GC-MS/MS). The geometric mean limits of quantitation (LOQs) were 53 and 6 microg/kg for the acetonitrile extraction and 48 and 7 microg/kg for the acetone-based extraction for GC-MS/SIM and GC-MS/MS, respectively. Mean percent recoveries and standard deviations from the ginseng fortified at 25, 100, and 500 microg/kg using GC-MS/SIM were 87 +/- 10, 88 +/- 8, and 86 +/- 10% from acetonitrile extracts and 88 +/- 13, 88 +/- 12, and 88 +/- 14% from acetone mixture extracts, respectively. The mean percent recoveries from the ginseng at the 25, 100, and 500 microg/kg levels using GC-MS/MS were 83 +/- 19, 90 +/- 13, and 89 +/- 11% from acetonitrile extracts and 98 +/- 20, 91 +/- 13, and 88 +/- 14% from acetone extracts, respectively. Twelve dried ginseng products were found to contain one or more of the following pesticides and their metabolites: BHCs (benzene hexachlorides, alpha-, beta-, gamma-, and delta-), chlorothalonil, chlorpyrifos, DDT (dichlorodiphenyl trichloroethane), dacthal, diazinon, iprodione, quintozene, and procymidone ranging from 4000 microg/kg. No significant differences were found between the two extraction solvents, and GC-MS/MS was found to be more specific and sensitive than GC-MS/SIM. The procedures described were shown to be effective in screening, identifying, confirming, and quantitating pesticides in commercial ginseng products.

  3. 丁二酮肟重量法测定双乙腈二氯化钯中钯的含量%Determination of palladium Content in Bis (acetonitrile) Palladium (Ⅱ)Chloride by Dimethylglyoxime Gravimetry Method

    Institute of Scientific and Technical Information of China (English)



    试样经盐酸-硝酸混合酸溶解,高氯酸冒烟,于盐酸体系中用丁二酮肟沉淀剂与溶液中的钯络合,形成沉淀,计算样品双乙腈二氯化钯中钯的质量分数。对样品的预处理和检测方法进行了研究和对比。试验证明,本方法准确、简便、有效,适用于双乙腈二氯化钯中钯含量的检测。%The analytic method of determining the content of palladium content by dimethylglyoxime gravimetry method in 5%(v/v) hydrochloric acid was used, with hydrochloric acid, nitric acid-perchloric acid melting, bis(acetonitrile)palladium(Ⅱ)chloride in the electric heating plate. The concentration of palladium content in solution was deposited by dimethylglyoxime gravimetry in order to calculate the sample mass fraction of palladium in bis(acetonitrile)palladium(Ⅱ)chloride. The methods for sample pretreatment and determination were studied and contrasted. The experiment proved that the accuracy of this method, this method is convenient and rapid, especially suitable for determining the content of palladium in bis(acetonitrile)palladium(Ⅱ)chloride.

  4. Unusual solvent effect on a SN2 reaction. A quantum-mechanical and kinetic study of the Menshutkin reaction between 2-amino-1-methylbenzimidazole and iodomethane in the gas phase and in acetonitrile. (United States)

    Melo, André; Alfaia, António J I; Reis, João Carlos R; Calado, António R T


    The quaternization reaction between 2-amino-1-methylbenzimidazole and iodomethane was investigated in the gas phase and in liquid acetonitrile. Both experimental and theoretical techniques were used in this study. In the experimental part of this work, accurate second-order rate constants were obtained for this reaction in acetonitrile from conductivity data in the 293-323 K temperature range and at ambient pressure. From two different empirical equations describing the effect of temperature on reaction rates, thermodynamic functions of activation were calculated. In the theoretical part of this work, the mechanism of this reaction was investigated in the gas phase and in acetonitrile. Two different quantum levels (B3LYP/[6-311++G(3df,3pd)/LanL2DZ]//B3LYP/[6-31G(d)/LanL2DZ] and B3LYP/[6-311++G(3df,3pd)/LanL2DZ]//B3LYP/[6-31+G(d)/LanL2DZ]) were used in the calculations, and the acetonitrile environment was modeled using the polarized continuum model (PCM). In addition, an atoms in molecules (AIM) analysis was made aiming to characterize possible hydrogen bonding. The results obtained by both techniques are in excellent agreement and lead to new insight into the mechanism of the reaction under examination. These include the identification and thermodynamic characterization of the relevant stationary species, the rationalization of the mechanistic role played by the solvent and the amine group adjacent to the nucleophile nitrogen atom, the proposal of alternative paths on the modeled potential energy surfaces, and the origin of the marked non-Arrhenius behavior of the kinetic data in solvent acetonitrile. In particular, the AIM analysis confirmed the operation of intermolecular hydrogen bonds between reactants and between products, both in the gas phase and in solution. It is also concluded that the unusual solvent effect on this Menshutkin reaction stems from the conjunction of a nucleophile possessing a relatively complex chemical structure with a dipolar aprotic

  5. Dynamics of ultrafast intramolecular charge transfer with 1-tert-butyl-6-cyano-1,2,3,4-tetrahydroquinoline (NTC6) in n-hexane and acetonitrile. (United States)

    Druzhinin, Sergey I; Kovalenko, Sergey A; Senyushkina, Tamara; Zachariasse, Klaas A


    The intramolecular charge transfer (ICT) reaction of 1-tert-butyl-6-cyano-1,2,3,4-tetrahydroquinoline (NTC6) in n-hexane and acetonitrile (MeCN) is investigated by picosecond fluorescence experiments as a function of temperature and by femtosecond transient absorption measurements at room temperature. NTC6 in n-hexane is dual fluorescent from a locally excited (LE) and an ICT state, with a quantum yield ratio Phi'(ICT)/Phi(LE) of 0.35 at +25 degrees C and 0.67 at -95 degrees C, whereas in MeCN mainly an ICT emission is observed. From the temperature dependence of Phi'(ICT)/Phi(LE) for NTC6 in n-hexane, an LE/ICT enthalpy difference DeltaH of -2.4 kJ/mol is determined. For comparison, 1-isopropyl-6-cyano-1,2,3,4-tetrahydroquinoline (NIC6) is also investigated. This molecule does not undergo an ICT reaction, because of its larger energy gap DeltaE(S1,S2). From the molar absorption coefficient epsilonmax of NTC6 as compared with other aminobenzonitriles, a ground-state amino twist angle theta of approximately 22 degrees is deduced. The increase of epsilonmax between n-hexane and MeCN indicates that theta decreases when the solvent polarity becomes larger. Whereas single-exponential LE fluorescence decays are obtained for NIC6 in n-hexane and MeCN, the LE and ICT decays of NTC6 in these solvents are double exponential. For NTC6 in n-hexane at -95 degrees C, with a shortest decay time of 20 ps, the forward (ka=2.5x10(10) s(-1)) and backward (kd=2.7x10(10) s(-1)) rate constants for the LEICT reaction are determined from the time-resolved LE and ICT fluorescence spectra. For NTC6 in n-hexane and MeCN, the excited-state absorption (ESA) spectrum at 200 fs after excitation is similar to the LE(ESA) spectra of NIC6 and 4-(dimethylamino)benzonitrile (DMABN), showing that LE is the initially excited state for NTC6. These results indicate that the LE states of NTC6, NIC6, and DMABN have a comparable molecular structure. The ICT(ESA) spectrum of NTC6 in n-hexane and Me

  6. Spectrophotometric Study of Adduct Formation Between [Co(Salen)PPh3]ClO4.H2O and [Co(7,7'-Dimethylsalen)PPh3]ClO4.H2O with Amines Donors in Acetonitrile



    The equilibrium quotient of the adduct formation of [Co(Salen)PPh3]ClO4.H2O and [Co(7,7'-dimethylSalen)PPh3]ClO4.H2O, as acceptor with amines donors are studied by spectrophotometer. Thermodynamics of these pentacoordinate cobalt(III) Schiff-base complexes have been examined with n-butylamine, sec-butylamine, tert-butylamine, benzylamine and diethylamine in constant ionic strength of 0.1 M sodium perchlorate and acetonitrile solvent at room temperature. We aimed to investigate the effects of ...

  7. Aqua(μ-cone-26,28-dibutoxy-25,27-bis{N-[5-(dimethylaminonaphthalene-1-sulfonyl]carbamoylmethoxy}-5,11,17,23-tetrakis(1,1-dimethylethylcalix[4]arene(2−disodium acetonitrile tetrasolvate

    Directory of Open Access Journals (Sweden)

    Pogisego Dinake


    Full Text Available The structure of the title complex, [Na2(C80H98N4O10S2(H2O]·4CH3CN, obtained after crystallization from acetonitrile, contains two formula units in the asymmetric unit (Z′ = 2 and an estimated four molecules of acetonitrile per calixarene moiety. It is unusual for two Na+ ions to occupy the lower rims of the cone calix[4]arene, as in this case, with one Na+ ion forming two O→ Na+ coordinate bonds with the two butoxy groups and four such bonds with the two N-dansyl carboxamide groups, forming six dative bonds between Na+ and O. On the other hand, the other Na+ ion forms only five O→Na+ coordinate bonds on the far end of the calix[4]arene lower rim, bringing the two dansyl groups in close proximity with each other. There also appears to be an O→Na+ coordination coming from a dangling water molecule. The structure contained both resolved and poorly resolved solvent molecules. The latter were treated using the SQUEEZE routine in PLATON [Spek (2009. Acta Cryst. D65, 148–155].

  8. Rhodococcus sp.BX2菌对乙腈的降解特性及降解途径研究%Characteristics and pathway of acetonitrile degradation by Rhodococcus sp.BX2

    Institute of Scientific and Technical Information of China (English)

    孙晶; 熊明华; 成小松; 李悦; 臧海莲; 李春艳


    对Rhodococcus sp.BX2菌降解乙腈的特性及其降解途径进行了研究.结果显示,在底物浓度为800mg·L-1,接种量为1.0%,培养温度为35℃,环境pH为7.5的条件下,16h时Rhodococcus sp.BX2菌对乙腈的降解率为95.98%;添加葡萄糖可在培养初期加快Rhodococcus sp.BX2菌的生长和对乙腈的降解,蔗糖、乙酰胺和尿素对其影响不大.将BX2菌接种到含有高乙腈浓度(25000mg·L-1)的合成废水中,培养180h后,乙腈降解率可达88.59%.在催化反应60min后,Rhodococcus sp.BX2腈水合酶与腈水解酶的总酶活可达到422.81U·mL-1,对其相关基因序列的分析结果表明,Rhodococcus sp.BX2中同时存在腈水解酶基因和腈水合酶基因,因此,确定乙腈的降解主要由腈水合酶途径完成,可能同时存在腈水解酶的降解途径.%The characteristics and pathway of acetonitrile degradation by Rhodococcus sp.BX2 were investigated in this study. Results showed that with the initial acetonitrile concentration of 800 mg · L-1, the degradation rate was 95.98% in 16 hours under the condition of inoculum 1.0%, 35 ℃ and pH value 7.5.Glucose could accelerate the degradation of acetonitrile in the initial period, while sucrose, acetamide and urea had slight impact. The degradation rate could reach 88.59% when BX2 was cultured in the synthetic wastewater with high concentration of acetonitrile (25000 mg · L-1) for 180 hours. Total enzyme activities was 422.81 U · mL-1 when incubated for 60 minutes. The results of related genes sequence showed that Rhodococcus sp BX2 had both nitrile hydrolase gene and nitrile hydratase gene. The degradation pathway of acetonitrile by Rhodococcus sp. BX2 was mainly nitrile hydratase (NHase), with possible pathway of the nitrile hydrolase.

  9. Spectrophotometric study of interaction of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone with diaza-18-crown-6 and diaza-15-crown-5 in acetonitrile and chloroform solutions (United States)

    Hasani, Masoumeh; Shamsipur, Mojtaba


    Interactions of diaza-18-crown-6 and diaza-15-crown-5, as electron donors, with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), as an electron acceptor, have been investigated spectrophotometrically in acetonitrile and chloroform solutions. The results indicated immediate formation of an electron donor-electron acceptor complex DA: D+A ⇌fastKDA which is followed by two relatively slow consecutive reactions: DA⟶kDA⟶kProduct The pseudo-first-order rate constants for the formation of the ionic intermediate and the final product have been evaluated at various temperatures by computer fitting of the absorbance time data to appropriate equations. The formation constants of the resulting DA complexes have also been determined. The influences of both the azacrown's structure and the solvent properties on the formation of DA complexes and the rates of subsequent reactions are discussed.

  10. Discussion on Determination Methods of Impurity Content in Acetonitrile at the Top of Vacuum Azeotropic Tower%减压共沸塔顶乙腈杂质含量测定方法探讨

    Institute of Scientific and Technical Information of China (English)

    崔凤艳; 王慧


      建立气相色谱法测定乙腈装置减压共沸塔顶(T202顶)粗乙腈杂质含量的分析方法。采用DB-FFAP毛细管色谱柱、氢火焰检测器,带范围校正归一化法定量。通过实验选择最佳分析操作条件,成功分析出粗乙腈中微量丙烯腈、丙酮、唑、丙腈等杂质含量。解决了填充柱在分析此样品时,主要杂质丙烯腈与未知杂质色噁谱峰重叠的问题。测定的相对标准偏差均小于5.0%,各组分加标回收率在97%~102%之间,能满足分析要求。%  A gas chromatography analysis method for determining impurity content in acetonitrile at the top of vacuum azeotropic tower was established through adopting capillary column DB-FFAP, flame ionization detector and correcting the area with normalization. The best analysis conditions were obtained through experiments, and impurity content in acetonitrile was successfully analyzed, such as trace acrylonitrile,acetone , oxazole , propionitrile and so on. The problem of overlapping chromatographic peaks in chromatography analysis with the packed column was solved. The relative standard deviation was less than 5.0%, the recovery rates of components were in the range of 97%~102%,so the method can satisfy the analysis requirement.

  11. 以苯胺为溶剂间歇萃取精馏分离甲醇-乙腈%Separation of methanol-acetonitrile by batch extractive distillation with aniline as solvent

    Institute of Scientific and Technical Information of China (English)

    于洋; 白鹏; 李广忠; 尹琨; 庄琼红


    提出和研究了以苯胺作为溶剂的甲醇-乙腈间歇萃取精馏分离工艺。根据溶剂极性相似相溶原理,结合ChemCAD软件模拟汽液平衡和汽液平衡实验确定苯胺为合适的溶剂。结果表明,不仅苯胺能够消除甲醇-乙腈物系的共沸现象,效果优于N,N-二甲基甲酰胺(DMF),而且可以采用Wilson模型对苯胺作为溶剂的甲醇-乙腈共沸物系汽液平衡进行模拟。通过实验考察了间歇萃取精馏的分离效果。采用有33块理论板的填料塔进行间歇萃取精馏甲醇-乙腈共沸混合物分离实验,其中净化回收段填料层3块理论板,萃取精馏段填料层30块理论板,回流比为4,苯胺作为溶剂,溶剂质量比为2.5∶1时,在塔顶得到产品甲醇质量分数为98.97%,高于DMF作为溶剂时的95.76%;表明苯胺更加适合作为萃取精馏分离甲醇-乙腈共沸物系的溶剂。%In this paper,aniline was proposed as the solvent for the separation of the azeotrope methanol-acetonitrile by batch extractive distillation and the process was studied.Aniline was selected as the suitable solvent on the basis of the law of similarity and dissolvability,combined with VLE simulation by ChemCAD software and the VLE experiments.The results show that aniline as the solvent could break the azeotrope and the effects of aniline were better than N,N-dimethylformamide(DMF).The Wilson model was used in VLE simulation.The experiment on the separation of the azeotrope methanol and acetonitrile by batch extractive distillation was carried out with a packed column with 33 theoretical plates among which 3 theoretical plates are in rectifying and recovery section and 30 theoretical plates in extractive distillation section.With the reflux ratio of 4,and the solvent mass ratio of 2.5∶1,the product purity of methanol reaches 98.97%,which is higher than the value of 95.76% when DMF was used as the solvent.It indicates that the extractive distillation with aniline as

  12. Structure, solvation, and dynamics of Mg{sup 2+}, Ca{sup 2+}, Sr{sup 2+}, and Ba{sup 2+} complexes with 3-hydroxyflavone and perchlorate anion in acetonitrile medium: A molecular dynamics simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Agieienko, Vira N.; Kolesnik, Yaroslav V.; Kalugin, Oleg N., E-mail: [Department of Inorganic Chemistry, V. N. Karazin Kharkiv National University, Kharkiv 61022 (Ukraine)


    Molecular dynamics simulations of complexes of Mg{sup 2+}, Ca{sup 2+}, Sr{sup 2+}, and Ba{sup 2+} with 3-hydroxyflavone (flavonol, 3HF) and ClO {sub 4}{sup −} in acetonitrile were performed. The united atoms force field model was proposed for the 3HF molecule using the results of DFT quantum chemical calculations. 3HF was interpreted as a rigid molecule with two internal degrees of freedom, i.e., rotation of the phenyl ring and of the OH group with respect to the chromone moiety. The interatomic radial distribution functions showed that interaction of the cations with flavonol occurs via the carbonyl group of 3HF and it is accompanied with substitution of one of the acetonitrile molecules in the cations’ first solvation shells. Formation of the cation–3HF complexes does not have significant impact on the rotation of the phenyl ring with respect to the chromone moiety. However, the orientation of the flavonol's OH-group is more sensitive to the interaction with doubly charged cations. When complex with Mg{sup 2+} is formed, the OH-group turns out of the plane of the chromone moiety that leads to rupture of intramolecular H-bond in the ligand molecule. Complexation of Ca{sup 2+}, Sr{sup 2+}, and BaClO {sub 4}{sup +} with 3HF produces two structures with different OH-positions, as in the free flavonol with the intramolecular H-bond and as in the complex with Mg{sup 2+} with disrupted H-bonding. It was shown that additional stabilization of the [MgClO{sub 4}(3HF)]{sup +} and [BaClO{sub 4}(3HF)]{sup +} complexes is determined by strong affinity of perchlorate anion to interact with flavonol via intracomplex hydrogen bond between an oxygen atom of the anion and the hydrogen atom of the 3-hydroxyl group. Noticeable difference in the values of the self-diffusion coefficients for Kt{sup 2+} from one side and ClO {sub 4}{sup −}, 3HF, and AN in the cations’ coordination shell from another side implies quite weak interaction between cation, anion, and ligands in

  13. Implementation of a statistically supported heuristic approach to alternating current voltammetric harmonic component analysis: re-evaluation of the macrodisk glassy carbon electrode kinetics for oxidation of ferrocene in acetonitrile. (United States)

    Mashkina, Elena; Bond, Alan M


    Sinusoidal large amplitude ac voltammetric techniques gene-rate very large data sets. When analyzed in the frequency domain, using a Fourier transform (FT)-band filtering- inverse FT sequence, the data may be resolved into the aperiodic dc, fundamental, second, and higher order ac harmonics. Each of these components exhibit a different level of sensitivity to electrode kinetics, uncompensated resistance and capacitance. Detailed simulations illustrate how the heuristic approach for evaluation of each data subset may be implemented and exploited in the assessment of the electrode kinetics for the fast Fc [symbol:see text] Fc(+) + e (Fc = ferrocene) oxidation process at a glassy carbon macrodisk electrode. The simulations presented in this study are based on the Butler-Volmer model and incorporate consideration of the uncompensated resistance (R(u)), double-layer capacitance (C(dl)), rate constant (k(0)), and charge transfer coefficient (α). Error analysis of the heuristically evaluated simulation-experiment comparison is used to assist in establishing the best fit of data for each harmonic. The result of the heuristic pattern recognition type approach for analysis of the oxidation of ferrocene (0.499, 0.999, and 5.00 mM) at a glassy carbon macrodisk electrode in acetonitrile (0.1 M Bu(4)NPF(6)) implies that k(0) ≥ 0.25 cm s(-1) on the basis of analysis of the first 4 harmonics and plausibly lies in the range of 0.25-0.5 cm s(-1) with α = 0.25-0.75 when analysis of the next four harmonics is undertaken. The k(0) value is significantly faster then indicated in most literature reports based on use of dc cyclic voltammetry under transient conditions at glassy carbon macrodisk electrode. The data analysis with a sinusoidal amplitude of 80 mV is conducted at very low frequency experiments of 9 Hz to minimize contribution from electrode heterogeneity, frequency dispersion, and adsorption, all of which can complicate the response for the oxidation of Fc in acetonitrile

  14. A validated liquid chromatographic method for the determination of polycyclic aromatic hydrocarbons in honey after homogeneous liquid-liquid extraction using hydrophilic acetonitrile and sodium chloride as mass separating agent. (United States)

    Koltsakidou, Anastasia; Zacharis, Constantinos K; Fytianos, Konstantinos


    In the present report, a simple and cost-effective method for the determination of twelve US EPA priority polycyclic aromatic hydrocarbons (PAHs) in honey samples after salting-assisted liquid-liquid extraction and UHPLC with fluorescence detection is proposed. The sample treatment is based on the usage of hydrophilic acetonitrile as extraction solvent and its phase separation under high salinity conditions. Due to the high sugar content of the samples the phase separation is promoted effortlessly. Several parameters affecting the extraction efficiency and method sensitivity including the concentration of the honey samples, the type and volume of the extraction solvent, the type and quantity of the inorganic salt, extraction time and centrifugation time was systematically investigated. The method was validated in-house according to the Commission Decision 2002/657/EC guidelines. The limit of detection (LOD) of the method lay between 0.02 and 0.04ngmL(-1) (corresponding to 0.08 and 0.16ngg(-1)) which are close to the quality criteria established by European Regulation (EC) 836/2011 concerning the PAHs in foodstuffs. The mean analytical bias (expressed as relative recoveries) in all spiking levels was acceptable being in the range of 54-118% while the relative standard deviation (RSD) was lower than 19%. The proposed method has been satisfactorily applied for the analysis of the selected PAHs residues in various honey samples obtained from Greek region.

  15. Evidence for a catalytic six-membered cyclic transition state in aminolysis of 4-nitrophenyl 3,5-dinitrobenzoate in acetonitrile: comparative brønsted-type plot, entropy of activation, and deuterium kinetic isotope effects. (United States)

    Um, Ik-Hwan; Kim, Min-Young; Bae, Ae-Ri; Dust, Julian M; Buncel, Erwin


    A kinetic study for reactions of 4-nitrophenyl 3,5-dinitrobenzoate (1a) with a series of cyclic secondary amines in acetonitrile is reported. Plots of the pseudo-first-order rate constant (kobsd) vs [amine] curve upward, while those of kobsd /[amine] vs [amine] exhibit excellent linear correlations with positive intercepts, indicating that the reaction proceeds through both uncatalyzed and catalyzed routes. Brønsted-type plots for uncatalyzed and catalyzed reactions are linear with βnuc = 1.03 and 0.69, respectively. The ΔH(⧧) and ΔS(⧧) values measured for the catalytic reaction with morpholine are -0.80 kcal/mol and -61.7 cal/(mol K), respectively. The negative ΔH(⧧) with a large negative ΔS(⧧) suggests that the reaction proceeds through a highly ordered transition state (i.e., a six-membered cyclic transition state, which includes a second amine molecule that accepts a proton from the aminium moiety of the zwitterionic tetrahedral intermediate and simultaneously donates a proton to the aryloxyl oxygen of the nucleofuge with concomitant C-OAr bond scission). This proposal is consistent with the smaller βnuc value for the catalyzed reaction as compared to the uncatalyzed reaction. An inverse deuterium kinetic isotope effect (DKIE) value of 0.93 and a contrasting normal primary DKIE value of 3.23 for the uncatalyzed and catalyzed routes, respectively, also support the proposed cyclic transition state.

  16. Crystal structure of tetrakis[μ2-2-(dimethylaminoethanolato-κ3N,O:O]di-μ3-hydroxido-dithiocyanato-κ2N-dichromium(IIIdilead(II dithiocyanate acetonitrile monosolvate

    Directory of Open Access Journals (Sweden)

    Julia A. Rusanova


    Full Text Available The tetranuclear complex cation of the title compound, [Cr2Pb2(NCS2(OH2(C4H10NO4](SCN2·CH3CN, lies on an inversion centre. The main structural feature of the cation is a distorted seco-norcubane Pb2Cr2O6 cage with a central four-membered Cr2O2 ring. The CrIII ion is coordinated in a distorted octahedron, which involves two N atoms of one bidentate ligand and one thiocyanate anion, two μ2-O atoms of 2-(dimethylaminoethanolate ligands and two μ3-O atoms of hydroxide ions. The coordination geometry of the PbII ion is a distorted disphenoid, which involves one N atom, two μ2-O atoms and one μ3-O atom. In addition, weak Pb...S interactions involving the coordinating and non-coordinating thiocyanate anions are observed. In the crystal, the complex cations are linked through the thiocyanate anions via the Pb...S interactions and O—H...N hydrogen bonds into chains along the c axis. The chains are further linked together via S...S contacts. The contribution of the disordered solvent acetonitrile molecule was removed with the SQUEEZE [Spek (2015. Acta Cryst. C71, 9–18] procedure in PLATON. The solvent is included in the reported molecular formula, weight and density.

  17. High-throughput salting-out assisted liquid-liquid extraction with acetonitrile for the determination of anandamide in plasma of hemodialysis patients with liquid chromatography tandem mass spectrometry. (United States)

    Xiong, Xin; Zhang, Lei; Cheng, Litao; Mao, Wei


    Anandamide (AEA) is an endocannabinoid present in human plasma that is associated with several physiological functions and disease states. However, low AEA plasma levels pose challenges in terms of analytical characterization. Classical liquid-based lipid extraction and solid-phase extraction require complicated procedures and the drying down of relatively large volumes of solvents, making them unsuitable for high-throughput analysis. Here a high-throughput salting-out assisted liquid-liquid extraction (SALLE) method with acetonitrile and mass spectrometry compatible salts for liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of AEA in human plasma has been developed and validated. The seamless interface of SALLE and LC-MS eliminated the drying-down step, only 100 μL of plasma is required and minimal volumes of organic solvent are used. Good reproducibility, accuracy and precision were demonstrated during the method validation. The method is linear up to 10 ng/mL with a lower limit of quantitation of 0.1 ng/mL for AEA, the accuracy for AEA was from 93.3 to 96.7% and the precision was <8.57%. This new methodology was successfully applied to analysis of clinical samples from maintenance hemodialysis patients.

  18. Retention of ionisable compounds on high-performance liquid chromatography. XV. Estimation of the pH variation of aqueous buffers with the change of the acetonitrile fraction of the mobile phase. (United States)

    Subirats, Xavier; Bosch, Elisabeth; Rosés, Martí


    The most commonly used mobile phases in reversed-phase high-performance liquid chromatography (RP-HPLC) are hydro-organic mixtures of an aqueous buffer and an organic modifier. The addition of this organic solvent to buffered aqueous solutions involves a variation of the buffer properties (pH and buffer capacity). In this paper, the pH variation is studied for acetic acid-acetate, phosphoric acid-dihydrogenphosphate-hydrogenphosphate, citric acid-dihydrogencitrate-citrate, and ammonium-ammonia buffers. The proposed equations allow pH estimation of acetonitrile-water buffered mobile phases up to 60% (v/v) of organic modifier and initial aqueous buffer concentrations between 0.001 and 0.1 mol L(-1), from the initial aqueous pH. The estimated pH variation of the mobile phase and the pKa variation of the analytes allow us to predict the degree of ionisation of the analytes and from this and analyte hydrophobicities, to interpret the relative retention and separation of analyte mixtures.

  19. Retention of ionisable compounds on high-performance liquid chromatography XVI. Estimation of retention with acetonitrile/water mobile phases from aqueous buffer pH and analyte pKa. (United States)

    Subirats, Xavier; Bosch, Elisabeth; Rosés, Martí


    In agreement with our previous studies and those of other authors, it is shown that much better fits of retention time as a function of pH are obtained for acid-base analytes when pH is measured in the mobile phase, than when pH is measured in the aqueous buffer when buffers of different nature are used. However, in some instances it may be more practical to measure the pH in the aqueous buffer before addition of the organic modifier. Thus, an open methodology is presented that allows prediction of chromatographic retention of acid-base analytes from the pH measured in the aqueous buffer. The model presented estimates the pH of the buffer and the pKa of the analyte in a particular acetonitrile/water mobile phase from the pH and pKa values in water. The retention of the analyte can be easily estimated, at a buffer pH close to the solute pKa, from these values and from the retentions of the pure acidic and basic forms of the analyte. Since in many instances, the analyte pKa values in water are not known, the methodology has been also tested by using Internet software, at reach of many chemists, which calculates analyte pKa values from chemical structure. The approach is successfully tested for some pharmaceutical drugs.

  20. Novel recombinant insulin analogue with flexible C-terminus in B chain. NMR structure of biosynthetic engineered A22G-B31K-B32R human insulin monomer in water/acetonitrile solution. (United States)

    Borowicz, Piotr; Bocian, Wojciech; Sitkowski, Jerzy; Bednarek, Elżbieta; Mikiewicz-Syguła, Diana; Błażej-Sosnowska, Sylwia; Bogiel, Monika; Rusek, Dorota; Kurzynoga, Dariusz; Kozerski, Lech


    A tertiary structure of recombinant A22(G)-B31(K)-B32(R)-human insulin monomer (insulin GKR) has been characterized by (1)H, (13)C NMR at natural isotopic abundance using NOESY, TOCSY, (1)H/(13)C-GHSQC, and (1)H/(13)C-GHSQC-TOCSY spectra. Translational diffusion studies indicate the monomer structure in water/acetonitrile (65/35vol.%). CSI analysis confirms existence of secondary structure motifs present in human insulin standard (HIS). Both techniques allow to establish that in this solvent recombinant insulin GKR exists as a monomer. Starting from structures calculated by the program CYANA, two different refinement protocols used molecular dynamics simulated annealing with the program AMBER; in vacuum (AMBER_VC), and including a generalized Born solvent model (AMBER_GB). From these calculations an ensemble of 20 structures of lowest energy was chosen which represents the tertiary structure of studied insulin. Here we present novel insulin with added A22(G) amino acid which interacts with β-turn environment resulting in high flexibility of B chain C-terminus.

  1. Rate theory of solvent exchange and kinetics of Li+ - BF4-/PF6- ion pairs in acetonitrile

    Energy Technology Data Exchange (ETDEWEB)

    Dang, Liem X. [Physical Science Division, Pacific Northwest National Laboratory, Richland, Washington 93352, USA; Chang, Tsun-Mei [Department of Chemistry, University of Wisconsin - Parkside, Kenosha, Wisconsin 53141, USA


    In this paper, we describe our efforts to apply rate theories in studies of solvent exchange around Li+(aq) and the kinetics of ion pairings in lithium-ion batteries (LIB). We report one of the first computer simulations of the exchange dynamics around hydrated Li+ in acetonitrile (ACN), which is common solvent used in LIBs. We also provide details of the ion-pairing kinetics of Li+-[BF4] and Li+-[PF6] in ACN. Using our polarizable force-field models and employing classical rate theories of chemical reactions, we examine the ACN exchange process between the first and second solvation shells around Li+(aq). We calculate exchange rates using transition state theory and weighted them with transmission coefficients determined by the reactive flux and Impey, Madden, and McDonald approaches and Grote-Hynes theory. We found the relaxation times changed from 180 ps to 4600 ps and from 30 ps to 280 ps for Li+-[BF4] and Li+-[PF6] ion pairs, respectively. These results confirm that the solvent response to the kinetics of ion pairing is significant. Our results also show that, in addition to affecting the free energy of solvation into ACN, the anion type also should significantly influence the kinetics of ion pairing. These results will increase our understanding of the thermodynamic and kinetic properties of LIB systems.

  2. NMR structure of biosynthetic engineered human insulin monomer B31(Lys)-B32(Arg) in water/acetonitrile solution. Comparison with the solution structure of native human insulin monomer. (United States)

    Bocian, Wojciech; Borowicz, Piotr; Mikołajczyk, Jerzy; Sitkowski, Jerzy; Tarnowska, Anna; Bednarek, Elzbieta; Głabski, Tadeusz; Tejchman-Małecka, Bozena; Bogiel, Monika; Kozerski, Lech


    A solution NMR-derived structure of a new long -acting, B31(Lys)-B32(Arg) (LysArg), engineered human insulin monomer, in H(2)O/CD(3)CN, 65/35 vol %, pH 3.6, is presented and compared with the available X-ray structure of a monomer that forms part of a hexamer (Smith, et al., Acta Crystallogr D 2003, 59, 474) and with NMR structure of human insulin in the same solvent (Bocian, et al., J Biomol NMR 2008, 40, 55-64). Detailed analysis using PFGSE NMR (Pulsed Field Gradient Spin Echo NMR) in dilution experiments and CSI analysis prove that the structure is monomeric in the concentration range 0.1-3 mM. The presence of long-range interstrand NOEs in a studied structure, relevant to the distances found in the crystal structure of the monomer, provides the evidence for conservation of the tertiary structure. Therefore the results suggest that this solvent system is a suitable medium for studying the native conformation of the protein, especially in situations (as found for insulins) in which extensive aggregation renders structure elucidations in water difficult or impossible. Starting from the structures calculated by the program CYANA, two different molecular dynamics (MD) simulated annealing refinement protocols were applied, either using the program AMBER in vacuum (AMBER_VC), or including a generalized Born solvent model (AMBER_GB). Here we present another independent evidence to the one presented recently by us (Bocian et al., J Biomol NMR 2008, 40, 55-64), that in water/acetonitrile solvent detailed structural and dynamic information can be obtained for important proteins that are naturally present as oligomers under native conditions.

  3. Isobaric Vapor-Liquid Equilibria ofAcetonitrile-Propan-1-ol-N, N-Dimethyl Formamide Systems%乙腈-正丙醇-N,N-二甲基甲酰胺体系的等压汽液平衡

    Institute of Scientific and Technical Information of China (English)

    曾红; 姚舜; 刘其松; 朱堂峰


    Isobaric vapor-liquid equilibrium (VLE) data of acetonitrile-Propan-l-ol, acetonitrile-N,N-dimethylformamide (DMF), Propan-1-ol-N,N-dimethylformamide (DMF) and acetonitrile-Propan-l-ol-N,N-dimethylformamide (DMF) systems were measured at 101.3 kPa by using an improved Rose still, and the VLE data of the binary systems were examined and pass the thermodynamic consistency test. Wilson and NRTL models were applied to correlate the VLE data for the three binary systems and the model parameters were obtained. The obtained Wilson and NRTL interaction parameters for the three binary systems were used to predict the VLE data of the ternary system. The predicted values agree well with the experimental results, and the average absolute deviations of the predicted vapor-phase molar fraction of acetonitrile, Propan-l-o1 and N,N-dimethylformamide (DMF) are less than 0.0124, 0.0146 and 0.0134, respectively, and the average absolute deviation of the equilibrium temperature is less than 1.00 K. The study results provide essential data for developing distill separation process of acetonitrile and Propan-l-ol with DMF.%用改进Rose釜测定了101.3 kPa下乙腈-正丙醇、乙腈- N,N-二甲基甲酰胺(DMF)、正丙醇-N,N-二甲基甲酰胺(DMF)、乙腈-正丙醇- N,N- 二甲基甲酰胺(DMF)体系的等压汽液平衡数据,并通过了热力学一致性检验,用Wilson、NRTL模型对三个二元体系的汽液平衡数据进行关联,效果良好.由关联得到的三个二元体系的Wilson、NRTL 模型参数预测部分三元体系的汽液平衡数据,乙腈、正丙醇及N,N-二甲基甲酰胺(DMF)汽相组成的平均绝对偏差分别小于0.0124、0.0146、0.0134,温度的平均绝对偏差小于1.00K.研究结果为加入DMF的萃取精馏分离乙腈和正丙醇混合物提供了重要的基础数据.

  4. Crystal structure of (2,11-diaza[3.3](2,6pyridinophane-κ4N,N′,N′′,N′′′(1,6,7,12-tetraazaperylene-κ2N1,N12ruthenium(II bis(hexafluoridophosphate acetonitrile 1.422-solvate

    Directory of Open Access Journals (Sweden)

    Thomas Brietzke


    Full Text Available In the title compound, [Ru(C14H16N4(C16H8N4](PF62·1.422CH3CN, discrete dimers of complex cations, [Ru(L–N4H2tape]2+ are formed {L–N4H2 = 2,11-diaza[3.3](2,6pyridinophane; tape = 1,6,7,12-tetraazaperylene}, held together by π–π stacking interactions via the tape ligand moieties with a centroid–centroid distance of 3.49 (2 Å, assisted by hydrogen bonds between the non-coordinating tape ligand α,α′-diimine unit and the amine proton of a 2,11-diaza[3.3](2,6-pyridinophane ligand of the opposite complex cation. The combination of these interactions leads to an unusual nearly face-to-face π–π stacking mode. Additional weak C—H...N, C—H...F, N—H...F and P—F...π-ring (tape, py (with F...centroid distances of 2.925–3.984 Å interactions are found, leading to a three-dimensional architecture. The RuII atom is coordinated in a distorted octahedral geometry, particularly manifested by the Namine—Ru—Namine angle of 153.79 (10°. The counter-charge is provided by two hexafluoridophosphate anions and the asymmetric unit is completed by acetonitrile solvent molecules of crystallization. Disorder was observed for both the hexafluoridophosphate anions as well as the acetonitrile solvate molecules, with occupancies for the major moieties of 0.801 (6 for one of the PF6 anions, and a shared occupancy of 0.9215 (17 for the second PF6 anion and a partially occupied acetonitrile molecule. A second CH3CN molecule is fully occupied, but 1:1 disordered across a crystallographic inversion center.

  5. Acilação de Friedel-Crafts do 2-metoxinaftaleno usando o ácido dodecafosfotúngstico suportado em sílica (HPW/SiO2 como catalisador e acetonitrila como solvente Friedel-Crafts acylation of the 2-methoxynaphthalene using the silica-supported dodecatungstophosphoric acid (HPW/SiO2 as catalyst and acetonitrile as solvent

    Directory of Open Access Journals (Sweden)

    Gil Luciano Guedes dos Santos


    Full Text Available The synthesis of fine chemicals intermediates using Friedel-Crafts acylation is one of the most important methods in chemical technology. In this work, the acylation of 2-methoxynaphthalene with acetic anhydride using a silica-supported dodecatungstophosphoric acid catalyst (HPW/SiO2 and acetonitrila as solvent was studied, showing that this reaction is a feasible alternative to produce intermediaries to replace the current methods of production. The reactions using acetonitrile solvent showed yields greater than or equal to the reactions using traditional solvents such as nitrobenzene and dichloroethane. Finally, the modified Eley-Rideal mechanism was proposed to elucidate the experimental data obtained.

  6. [μ2-trans-1,2-Bis(pyridin-4-ylethene-κ2N:N′]bis{[1,2-bis(pyridin-4-ylethene-κN]bis[N-(2-hydroxyethyl-N-isopropyldithiocarbamato-κ2S,S′]cadmium} acetonitrile tetrasolvate: crystal structure and Hirshfeld surface analysis

    Directory of Open Access Journals (Sweden)

    Mukesh M. Jotani


    Full Text Available The asymmetric unit of the title compound, [Cd2(C12H10N23(C6H12NOS24]·4C2H3N, comprises a CdII atom, two dithiocarbamate (dtc anions, one and a half trans-1,2-dipyridin-4-ylethylene (bpe molecules and two acetonitrile solvent molecules. The full binuclear complex is generated by the application of a centre of inversion. The dtc ligands are chelating, one bpe molecule coordinates in a monodentate mode while the other is bidentate bridging. The resulting cis-N2S4 coordination geometry is based on an octahedron. Supramolecular layers, sustained by hydroxy-O—H...O(hydroxy and hydroxy-O—H...N(bpe hydrogen bonding, interpenetrate to form a three-dimensional architecture; voids in this arrangement are occupied by the acetonitrile solvent molecules. Additional intermolecular interactions falling within the specified framework have been analysed by Hirshfeld surface analysis, including π–π interactions.

  7. (1,6,7,12-Tetraazaperylene-κ2N,N′bis(4,4′,5,5′-tetramethyl-2,2′-bipyridyl-κ2N,N′ruthenium(II bis(hexafluoridophosphate acetonitrile trisolvate

    Directory of Open Access Journals (Sweden)

    Thomas Brietzke


    Full Text Available In the title compound, rac-[Ru(C14H16N22(C16H8N4](PF62·3C2H3N, discrete dimers of complex cations, [Ru(tmbpy2tape]2+, of opposite chirality are formed (tmbpy = tetramethylbipyridine; tape = tetraazaperylene, held together by π–π stacking interactions between the tetraazaperylene moieties with centroid–centroid distances in the range 3.563 (3–3.837 (3 Å. These interactions exhibit a parallel displaced π–π stacking mode. Additional weak C—H...π-ring and C—H...N and C—H...F interactions are found, leading to a three-dimensional architecture. The RuII atom is coordinated in a distorted octahedral geometry. The counter-charge is provided by two hexafluoridophosphate anions and the asymmetric unit is completed by three acetonitrile solvent molecules of crystallization. Four F atoms of one PF6− anion are disordered over three sets of sites with occupancies of 0.517 (3:0.244 (3:0.239 (3. Two acetonitrile solvent molecules are highly disordered and their estimated scattering contribution was subtracted from the observed diffraction data using the SQUEEZE option in PLATON [Spek (2009. Acta Cryst. D65, 148–155].

  8. Vapor-Liquid Equilibrium for Methanol-Acetonitrile-1-Butyl-3-Methylimidazolium Tetrafluoroborate Ternary System%甲醇-乙腈-1-丁基-3-甲基咪唑四氟硼酸盐三组分物系的汽液平衡

    Institute of Scientific and Technical Information of China (English)

    李群生; 王海川; 冉晓萌; 朱炜; 付永泉; 王宝华


    在101.32 kPa下,用CE-2型Othmer汽液平衡釜测定了甲醇-乙腈-1-丁基-3-甲基咪唑四氟硼酸盐([bmim]BF4)三组分物系的等压汽液平衡数据;采用UNIFAC方程对实验数据进行了关联.实验结果表明,与未加入[bmim]BF4相比,加入[bmim]BF4后甲醇-乙腈二组分物系的汽液平衡线产生偏离,[bmim]BF4含量越高,偏离程度越大;[bmim]BF4具有明显的盐析效应,当[bmim]BF4的含量为10%(x)时,甲醇-乙腈物系的共沸点消失;UNIFAC方程可用于预测甲醇-乙腈-[bmim]BF4三组分物系的汽液平衡.%Isobaric vapor-liquid equilibrium for methanol-acetonitrile-1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4) ternary system was measured at 101.32 kPa using CE-2 Othmer vapor-liquid equilibrium still. UNIFAC equations were used to correlate the experimental data. The experimental results indicated that the vapor-liquid equilibrium curves of the methanol-acetonitrile-. [bmim]BF4 system deviated from that of the [bmim]BF4-free system and the deviation increased with the increase of the [bmim]BF4 dosage. The ionic liquid [bmim]BF4 exhibited notable salt-out effect which could enhance the relative volatility. When the mole fraction of [bmim]BF4 amounted to 10%, the azeotropic point disappeared. UNIFAC equation can be used to predict the equilibrium of methanol-acetonitrile- [bmim]BF4 system.

  9. Crystal structure of (2,11-di-aza-[3.3](2,6)pyridino-phane-κ (4) N,N',N'',N''')(1,6,7,12-tetra-aza-perylene-κ (2) N (1),N (12))ruthenium(II) bis-(hexa-fluorido-phosphate) aceto-nitrile 1.422-solvate. (United States)

    Brietzke, Thomas; Rottke, Falko Otto; Kelling, Alexandra; Schilde, Uwe; Holdt, Hans-Jürgen


    In the title compound, [Ru(C14H16N4)(C16H8N4)](PF6)2·1.422CH3CN, discrete dimers of complex cations, [Ru(L-N4H2)tape](2+) are formed {L-N4H2 = 2,11-di-aza-[3.3](2,6)pyridino-phane; tape = 1,6,7,12-tetra-aza-perylene}, held together by π-π stacking inter-actions via the tape ligand moieties with a centroid-centroid distance of 3.49 (2) Å, assisted by hydrogen bonds between the non-coordinating tape ligand α,α'-di-imine unit and the amine proton of a 2,11-di-aza-[3.3](2,6)-pyridino-phane ligand of the opposite complex cation. The combination of these inter-actions leads to an unusual nearly face-to-face π-π stacking mode. Additional weak C-H⋯N, C-H⋯F, N-H⋯F and P-F⋯π-ring (tape, py) (with F⋯centroid distances of 2.925-3.984 Å) inter-actions are found, leading to a three-dimensional architecture. The Ru(II) atom is coordinated in a distorted octa-hedral geometry, particularly manifested by the Namine-Ru-Namine angle of 153.79 (10)°. The counter-charge is provided by two hexa-fluorido-phosphate anions and the asymmetric unit is completed by aceto-nitrile solvent mol-ecules of crystallization. Disorder was observed for both the hexa-fluorido-phosphate anions as well as the aceto-nitrile solvate mol-ecules, with occupancies for the major moieties of 0.801 (6) for one of the PF6 anions, and a shared occupancy of 0.9215 (17) for the second PF6 anion and a partially occupied aceto-nitrile mol-ecule. A second CH3CN mol-ecule is fully occupied, but 1:1 disordered across a crystallographic inversion center.

  10. 乙腈-NaCl-H2O双水相萃取ICP-AES测定食盐中的铜和铅%Development of Acetonitrile-NaCl-H2O Two-Phase Extraction Combined with ICP-AES for Determination of Copper and Lead in Salt

    Institute of Scientific and Technical Information of China (English)

    高福凯; 贾风燕; 陈璐思; 李桂芝; 刘振波; 刘永明


    In this study, a simple and efficient acetonitrile-sodium-H2O chloride aqueous two-phase system ( ATPS) is developed coupled with inductively coupled plasma atomic emission spectrometry (ICP-AES) for the extraction and the determination of cooper and lead in salt. Samples are pretreated by ATPS with 1-Pyrrolidinecar-bodithioic acid ammonium salt ( APDC) used as complex agent. The phase separation conditions and extraction efficiency factors, such as pH value and mass fraction of acetonitrile are investigated and optimized. The recoveries of copper and lead are 106. 0% and 96. 2% , RSD are 0. 76% and 0. 83% , and limits of detection are 5. 0 × 10-4 mg·kg-1 and 2. 3 ×10-2mg·kg-1 .respectively. The proposed method can be successfully applied for the pretreat-ment and determination of copper and lead in real salt samples. The results show that the interference of salt matrix with Cu and Pb determination using ICP-AES can be removed by the suggested method.%研究了乙腈-NaCl-H2O双水相体系的分相条件及在吡咯烷二硫代氨基甲酸铵(APDC)做络合剂时对铜和铅的萃取行为,并结合电感耦合等离子体原子发射光谱仪(ICP-AES)建立了一种测定食盐中铜和铅的方法.该方法在萃取Cu和Pb的同时去除了大量的NaCl基体,从而在ICP-AES测定食盐中痕量Cu、Pb时,去除了高盐的基体干扰.实验中铜和铅的平均回收率分别可以达到106.0%和96.2%,RSD为0.76%和0.83%,计算得出检出限分别为5.0×10-4 mg·kg-1和2.3 × 10-2 mg·kg-1,结果令人满意.该方法为高盐样品中金属离子的检测提供了一种新思路.

  11. 乙腈-硫酸铵-水双水相萃取-高效液相色谱法测定地下水中苯并(a)芘和苯并(e)芘%Extraction and Detection of Benzo(a) pyrene and Benzo(e) pyrene in Groundwater Using Acetonitrile-(NH4)2 SO4-Water System Coupled with Liquid Chromatography

    Institute of Scientific and Technical Information of China (English)

    王磊; 安彩秀; 朱裕穗; 肖凡; 刘金巍


    传统的液液萃取技术主要采用与水不相溶的有机溶剂作萃取剂,这种异相萃取的传质速率一般较低,需反复振荡或多次萃取.本文建立了以乙腈-硫酸铵-水的双水相萃取体系高效液相色谱法测定地下水中苯并(a)芘和苯并(e)芘的方法,以密度比水小的乙腈为萃取剂,将其与水样混合(互溶)获得乙腈-水体系,然后加入硫酸铵,溶液澄清、分相后取上层有机相(乙腈)进样分析.考察了萃取剂的选择、双水相的形成条件、离子强度以及pH等对测定结果的影响.两种化合物线性范围为2.00~ 400.00 ng/mL,相关系数大于0.999.方法检出限为0.012~0.020 ng/mL,平均回收率为94.6%~97.3%,相对标准偏差为1.3% ~2.5%.与传统萃取方法相比,该方法具有操作流程简单、快速的特点,可实现对野外环境水样进行原地样品前处理.%Conventional liquid-liquid extraction (LLE) methods usually use water immiscible organic solvents as the extraction solvents and achieve phase separation through repeated shock or multiple extractions. In this paper, a new method for the determination of benzo( a) pyrene and benzo (e) pyrene in groundwater by High Performance Liquid Chromatography ( HPLC ) with acetonitrile-( NH4 )2 SO4-water extraction system is described. In the proposed extraction procedure, a low-density extraction solvent (acetonitrile) was injected into a water sample to form the acetonitrile-water system. A salt (ammonium sulfate) was then injected into the acetonitrile-water solution to separate the system into two phases. The upper organic phase ( acetonitrile) was collected and analyzed by HPLC. All the parameters, such as the selection of extraction agent, aqueous two phase formation conditions, ionic strength and pH, are discussed and optimized. The two kinds of compound are linear and in the range of 2. 00 -400.00 ng/mL, and the correlation coefficient (R2) is greater than 0.999. The detection

  12. Adsorption of Dibenzothiophene in Acetonitrile on Fe3 +/Cu2 +/Ag+-Modified Activated Carbons with High Specific Surface Area%Fe3+/Cu2+/Ag+改性高比表面活性炭对乙腈中二苯并噻吩的吸附

    Institute of Scientific and Technical Information of China (English)

    李忠; 张红; 夏启斌; 张伟; 余谟鑫


    应用浸渍法,采用Fe3+、Cu2+和Ag+对高比表面活性炭(AC)进行改性,制备出3种改性的AC(Fe3 +/AC、Cu2 +/AC和Ag+/AC).采用静态吸附法测定改性AC吸附乙腈溶液中二苯并噻吩(DBT)的吸附等温线,应用程序升温脱附法(TPD)测定DBT在未改性AC及3种改性AC上的脱附峰面积,并采用Boehm滴定法测定这4种吸附剂的表面总酸性基团含量.结果表明:与未改性的AC相比,Fe3+/AC、Cu2+/AC和Ag+/AC表面的总酸性基团含量增加,其对乙腈溶液中DBT的吸附容量也增大;各吸附剂表面的总酸性基团含量顺序为Fea+/AC>Cu2+/AC>Ag+/AC>未改性AC,它们对乙腈溶液中DBT的吸附能力在298K下分别提高了30%、20%、14%.以上结果表明AC类吸附剂的吸附容量与其表面的酸性基团含量成正比;应用浸渍法可提高吸附剂表面的酸性基团含量,从而增加吸附剂表面吸附乙腈溶液中DBT的吸附活性位,提高对DBT的吸附能力.%In this paper, first, activated carbon ( AC) with high specific surface area was modified with metal ions Fe 3+ , Cu1 + and Ag+ through an impregnation process, and three kinds of modified AC, namely, Fe3 + /AC, Cu2 + / AC and Ag + /AC, were prepared. Next, the products were used to adsorb the dibenzothiophene (DBT) in acetonitrile solution, and the corresponding isotherms were obtained by means of the static adsorption method. Then, the desorption peak areas of DBT desorbed from the AC before and after the modification were measured through temperature-programmed desorption (TPD) experiments. Finally, the total amount of acidic functional groups on the surfaces of these four kinds of AC was measured via the Boehm titration. The results show that, after the modification , both the total amount of acidic functional groups and the adsorption capacity for DBT increase, that the total amount of acidic functional groups follows the order of Fe3 + /AC > Cu2 + /AC > Ag+ /AC > AC, with the adsorption capacity

  13. Synthesis and Characterization of 2- [ 4- ( 4,6-Dimethoxypyrimidin-2-yloxy ) -2-methylphenyl ] -2- ( substituted phenylamino ) acetonitrile Derivatives%2-[4-(4,6-二甲氧基嘧啶-2-氧基)-2-甲基苯基]-2-(取代苯胺)乙腈类衍生物的合成与表征

    Institute of Scientific and Technical Information of China (English)

    晏小红; 王育园; 李元祥


    为了寻求具有除草活性的化合物,以3-甲基苯酚为起始原料,通过酰化反应及取代反应合成了中间体4-(4,6-二甲氧基嘧啶-2-氧基)-2-甲基苯甲醛(Ⅲ),运用中间体(Ⅲ)通过三组分一锅法合成了12个2-[4-(4,6-二甲氧基嘧啶-2-氧基)-2-甲基苯基]-2-(取代苯胺)乙腈类衍生物,三组分反应具有良好的收率,为64%~96%.所合成化合物的结构经核磁共振氢谱、质谱和元素分析进行了表征.%In order to find out the molecular structures of a type of compounds with herbicidal activities, intermediate 4-( 4, 6-dimethoxypyrimidin-2-yloxy )-2-methylbenzaldehyde ( Ⅲ ) was synthesized usingm-cresol as starting material by acylation reaction and substitution reaction. Twelve 2-[4-(4, 6-dimethoxypyrimidin-2-yloxy )-2-methylphenyl ]-2-( substituted phenylamino ) acetonitrile derivative compounds have been synthesized using intermediate ( Ⅲ ) via three-component-one-pot reaction, and the yields were 64% ~ 96%. The structures of all synthesized compounds were confirmed by 1HNMR.MS and elemental analysis techniques.

  14. Bis{(E-3-[2-(hydroxyiminopropanamido]-2,2-dimethylpropan-1-aminium} bis[μ-(E-N-(3-amino-2,2-dimethylpropyl-2-(hydroxyiminopropanamido(2−]bis{[(E-N-(3-amino-2,2-dimethylpropyl-2-(hydroxyiminopropanamide]copper(II} bis((E-{3-[2-(hydroxyiminopropanamido]-2,2-dimethylpropyl}carbamate acetonitrile disolvate

    Directory of Open Access Journals (Sweden)

    Andrii I. Buvailo


    Full Text Available The reaction between copper(II nitrate and (E-N-(3-amino-2,2-dimethylpropyl-2-(hydroxyiminopropanamide led to the formation of the dinuclear centrosymmetric copper(II title complex, (C8H18N3O22[Cu2(C8H15N3O22(C8H17N3O22](C9H16N3O42·2CH3CN, in which an inversion center is located at the midpoint of the Cu2 unit in the center of the neutral [Cu2(C8H15N3O22(C8H17N3O22] complex fragment. The Cu2+ ions are connected by two N—O bridging groups [Cu...Cu separation = 4.0608 (5 Å] while the CuII ions are five-coordinated in a square-pyramidal N4O coordination environment. The complex molecule co-crystallizes with two molecules of acetonitrile, two molecules of the protonated ligand (E-3-[2-(hydroxyiminopropanamido]-2,2-dimethylpropan-1-aminium and two negatively charged (E-{3-[2-(hydroxyiminopropanamido]-2,2-dimethylpropyl}carbamate anions, which were probably formed as a result of condensation between (E-N-(3-amino-2,2-dimethylpropyl-2-(hydroxyiminopropanamide and hydrogencarbonate anions. In the crystal, the complex fragment [Cu2(C8H15N3O22(C8H17N3O22] and the ion pair C8H18N3O2+.C9H16N3O4− are connected via an extended system of hydrogen bonds.

  15. Crystal structure of tetra-kis-[μ2-2-(di-methyl-amino)-ethano-lato-κ(3) N,O:O]di-μ3-hydroxido-di-thio-cyanato-κ(2) N-dichromium(III)dilead(II) di-thio-cyanate aceto-nitrile monosolvate. (United States)

    Rusanova, Julia A; Semenaka, Valentyna V; Omelchenko, Irina V


    The tetra-nuclear complex cation of the title compound, [Cr2Pb2(NCS)2(OH)2(C4H10NO)4](SCN)2·CH3CN, lies on an inversion centre. The main structural feature of the cation is a distorted seco-norcubane Pb2Cr2O6 cage with a central four-membered Cr2O2 ring. The Cr(III) ion is coordinated in a distorted octa-hedron, which involves two N atoms of one bidentate ligand and one thio-cyanate anion, two μ2-O atoms of 2-(di-methyl-amino)-ethano-late ligands and two μ3-O atoms of hydroxide ions. The coordination geometry of the Pb(II) ion is a distorted disphenoid, which involves one N atom, two μ2-O atoms and one μ3-O atom. In addition, weak Pb⋯S inter-actions involving the coordinating and non-coordinating thio-cyanate anions are observed. In the crystal, the complex cations are linked through the thio-cyanate anions via the Pb⋯S inter-actions and O-H⋯N hydrogen bonds into chains along the c axis. The chains are further linked together via S⋯S contacts. The contribution of the disordered solvent aceto-nitrile mol-ecule was removed with the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] procedure in PLATON. The solvent is included in the reported mol-ecular formula, weight and density.

  16. Bis-{(E)-3-[2-(hy-droxy-imino)-propan-amido]-2,2-dimethyl-propan-1-aminium} bis[μ-(E)-N-(3-amino-2,2-dimethyl-prop-yl)-2-(hy-droxy-imino)-propanamido-(2-)]bis-{[(E)-N-(3-amino-2,2-dimethyl-prop-yl)-2-(hy-droxy-imino)-propanamide]-copper(II)} bis-((E)-{3-[2-(hy-droxy-imino)-propanamido]-2,2-dimethyl-prop-yl}carbamate) acetonitrile disolvate. (United States)

    Buvailo, Andrii I; Pavlishchuk, Anna V; Penkova, Larysa V; Kotova, Natalia V; Haukka, Matti


    The reaction between copper(II) nitrate and (E)-N-(3-amino-2,2-dimethyl-prop-yl)-2-(hy-droxy-imino)-propanamide led to the formation of the dinuclear centrosymmetric copper(II) title complex, (C8H18N3O2)2[Cu2(C8H15N3O2)2(C8H17N3O2)2](C9H16N3O4)2·2CH3CN, in which an inversion center is located at the midpoint of the Cu2 unit in the center of the neutral [Cu2(C8H15N3O2)2(C8H17N3O2)2] complex fragment. The Cu(2+) ions are connected by two N-O bridging groups [Cu⋯Cu separation = 4.0608 (5) Å] while the Cu(II) ions are five-coordinated in a square-pyramidal N4O coordination environment. The complex mol-ecule co-crystallizes with two mol-ecules of acetonitrile, two mol-ecules of the protonated ligand (E)-3-[2-(hy-droxy-imino)-propanamido]-2,2-dimethyl-propan-1-aminium and two negatively charged (E)-{3-[2-(hy-droxy-imino)-propanamido]-2,2-dimethyl-prop-yl}carbamate anions, which were probably formed as a result of condensation between (E)-N-(3-amino-2,2-dimethyl-prop-yl)-2-(hy-droxy-imino)-propanamide and hydro-gencarbonate anions. In the crystal, the complex fragment [Cu2(C8H15N3O2)2(C8H17N3O2)2] and the ion pair C8H18N3O2(+.)C9H16N3O4(-) are connected via an extended system of hydrogen bonds.

  17. An acetonitrile solvatomorph of dichlorido(1,10-phenanthroline-5,6-dioneplatinum(II

    Directory of Open Access Journals (Sweden)

    Amanda Hamala


    Full Text Available In the title complex, [PtCl2(C12H6N2O2]·CH3CN, the PtII atom lies in a slightly distorted square-planar arrangement defined by an N2Cl2 donor set. In the packed structure, columns of complex moieties are stacked such that the neighboring units are oriented at 180° and laterally displaced with respect to each other. This prevents any overlap of the phenanthroline rings and thus there is no possibility of any π–π interactions between aromatic rings.

  18. Bis{S-benzyl 3-[(phenyl(pyridin-2-ylmethylidene]dithiocarbazato}zinc acetonitrile monosolvate

    Directory of Open Access Journals (Sweden)

    Thahira B. S. A. Ravoof


    Full Text Available In the title compound, [Zn(C20H16N3S22]·CH3CN, two different Schiff base moieties coordinate to the central ZnII ion as tridentate N,N′,S-chelating ligands, creating a distorted octahedral environment [the smallest angle being 73.24 (6° and the widest angle being 155.73 (7°], with the two S atoms in cis positions. The dihedral angle between the mean planes of the two coordinating ligands is 83.65 (5°. The crystal packing is consolidated by weak C—H...N hydrogen-bonding interactions.

  19. Rhenium-mediated coupling of acetonitrile and pyrazoles. New molecular clefts for anion binding. (United States)

    Arroyo, Marta; Miguel, Daniel; Villafañe, Fernando; Nieto, Sonia; Pérez, Julio; Riera, Lucía


    The reaction of fac-[ReBr(CO)3(NCMe)2] (1) with either pyrazole (Hpz) or 3,5-dimethylpyrazole (Hdmpz) in a 1:2 Re/pyrazole ratio affords the known complexes fac-[ReBr(CO)3(Hpz)2] (2) and [ReBr(CO)3(Hdmpz)2] (3). Using a 1:1 ratio, MeCN as solvent, and longer reaction times led to a mixture in which the major components are the pyrazolylamidino complexes fac-[ReBr(CO)3(HN=C(CH3)pz-kappa2N,N)] (4) and fac-[ReBr(CO)3(HN=C(CH3)dmpz-kappa2N,N)] (5). The complexes fac-[ReBr(CO)3(Hpz)(NCMe)] (6) and fac-[ReBr(CO)3(Hdmpz)(NCMe)] (7) (along with 2 and 3) were found to be minor components of these reactions. Analogous reactions of fac-[Re(OClO3)(CO)3(NCMe)2] yielded fac-[Re(NCCH3)(CO)3(HN=C(CH3)pz-kappa2N,N)]ClO4 (8), fac-[Re(NCCH3)(CO)3(HN=C(CH3)dmpz-kappa2N,N)]ClO4 (9), fac-[Re(Hpz)(CO)3(HN=C(CH3)pz-kappa2N,N)]ClO4 (10), and fac-[Re(Hdmpz)(CO)3(HN=C(CH3)dmpz-kappa2N,N)]ClO4 (11). The X-ray structure of 11 showed the perchlorate anion to be hydrogen-bonded by the N-H groups of the pyrazole and pyrazolylamidino ligands. The behavior of the compound fac-[Re(Hdmpz)(CO)3(HN=C(CH3)dmpz-kappa2N,N)]BAr'4 (13) (synthesized by reaction of [ReBr(CO)3(Hdmpz)2] (3) with (i) AgOTf and (ii) NaBAr'(4)/MeCN) as an anion receptor has been studied in CD3CN solution. In addition, the structure of the supramolecular adduct fac-[Re(CO)3(Hdmpz)(HN=C(CH3)dmpz-kappa2N,N)].Cl (14), featuring chloride binding by the two N-H groups, was determined by X-ray diffraction.

  20. 78 FR 14241 - Acetonitrile; Community Right-to-Know Toxic Chemical Release Reporting (United States)


    ..., confusion, hyperpnea, dyspnea, rapid pulse, unconsciousness, and convulsions (Ref. 9). Cyanide was detected... convulsions in various studies (Ref. 9). 2. Effects of Subchronic and Chronic Exposure Subchronic inhalation... week. Ataxia, abnormal posture, and clonic convulsions occurred in the 1,600 ppm males that died....

  1. Bis­{(E)-3-[2-(hy­droxy­imino)­propan­amido]-2,2-dimethyl­propan-1-aminium} bis[μ-(E)-N-(3-amino-2,2-dimethyl­prop­yl)-2-(hy­droxy­imino)­propanamido­(2−)]bis­{[(E)-N-(3-amino-2,2-dimethyl­prop­yl)-2-(hy­droxy­imino)­propanamide]­copper(II)} bis­((E)-{3-[2-(hy­droxy­imino)­propanamido]-2,2-dimethyl­prop­yl}carbamate) acetonitrile disolvate (United States)

    Buvailo, Andrii I.; Pavlishchuk, Anna V.; Penkova, Larysa V.; Kotova, Natalia V.; Haukka, Matti


    The reaction between copper(II) nitrate and (E)-N-(3-amino-2,2-dimethyl­prop­yl)-2-(hy­droxy­imino)­propanamide led to the formation of the dinuclear centrosymmetric copper(II) title complex, (C8H18N3O2)2[Cu2(C8H15N3O2)2(C8H17N3O2)2](C9H16N3O4)2·2CH3CN, in which an inversion center is located at the midpoint of the Cu2 unit in the center of the neutral [Cu2(C8H15N3O2)2(C8H17N3O2)2] complex fragment. The Cu2+ ions are connected by two N—O bridging groups [Cu⋯Cu separation = 4.0608 (5) Å] while the CuII ions are five-coordinated in a square-pyramidal N4O coordination environment. The complex mol­ecule co-crystallizes with two mol­ecules of acetonitrile, two mol­ecules of the protonated ligand (E)-3-[2-(hy­droxy­imino)­propanamido]-2,2-dimethyl­propan-1-aminium and two negatively charged (E)-{3-[2-(hy­droxy­imino)­propanamido]-2,2-dimethyl­prop­yl}carbamate anions, which were probably formed as a result of condensation between (E)-N-(3-amino-2,2-dimethyl­prop­yl)-2-(hy­droxy­imino)­propanamide and hydro­gencarbonate anions. In the crystal, the complex fragment [Cu2(C8H15N3O2)2(C8H17N3O2)2] and the ion pair C8H18N3O2 +.C9H16N3O4 − are connected via an extended system of hydrogen bonds. PMID:23468704

  2. Effect of Growth Temperature on Bamboo-shaped Carbon–Nitrogen (C–N Nanotubes Synthesized Using Ferrocene Acetonitrile Precursor

    Directory of Open Access Journals (Sweden)

    Dobal PramodSingh


    Full Text Available Abstract This investigation deals with the effect of growth temperature on the microstructure, nitrogen content, and crystallinity of C–N nanotubes. The X-ray photoelectron spectroscopic (XPS study reveals that the atomic percentage of nitrogen content in nanotubes decreases with an increase in growth temperature. Transmission electron microscopic investigations indicate that the bamboo compartment distance increases with an increase in growth temperature. The diameter of the nanotubes also increases with increasing growth temperature. Raman modes sharpen while the normalized intensity of the defect mode decreases almost linearly with increasing growth temperature. These changes are attributed to the reduction of defect concentration due to an increase in crystal planar domain sizes in graphite sheets with increasing temperature. Both XPS and Raman spectral observations indicate that the C–N nanotubes grown at lower temperatures possess higher degree of disorder and higher N incorporation.

  3. Synthesis and Crystal Structure of Bis(μ-bis(diphenyl-phosphino)methane)(μ-benzenethiolate)(acetonitrile)Dicopper(I) Perchlorate Diethylether Solvate

    Institute of Scientific and Technical Information of China (English)

    陈燕丹; 张礼仪; 陈忠宁


    The reaction between [Cu2(μ-dppm)2(MeCN)4](ClO4)2(dppm=bis(diphenylphos-phino)methane) and [Zn(PhS)2(bpy)] (bpy=2,2'-bipyridine,PhS=benzenethiolate) gave the complex [Cu2(μ-dppm)2(μ-PhS)(MeCN)]ClO4·0.5(Et2O)(C58H52ClNO4P4SCu2·0.5Et2O) which was determined by X-ray single-crystal diffraction.The crystal is of orthorhombic,space group P212121 with a=13.6157(3),b=20.8022(6),c=21.3299(6)A,V=6041.4(3) A3,Mr=1182.54,Dc=1.300 g/cm3,F(000)=2444,μ=0.934 mm-1 and Z=4.The final R=0.0773 and wR=0.1843 for 7744 observed reflections (I>2σ(I)).The dicopper atoms are doubly bridged by dppm as well as one S donor from benzenethiolate.One copper atom is in a distorted trigonal bipyramidal environ- ment,whereas the other adopts a distorted tetrahedral geometry.

  4. Spectroscopic characterization of phenazinium dye aggregates in water and acetonitrile media: effect of methyl substitution on the aggregation phenomenon. (United States)

    Sarkar, Deboleena; Das, Paramita; Girigoswami, Agnishwar; Chattopadhyay, Nitin


    Absorption, fluorescence, and fluorescence excitation spectral studies of two planar, cationic phenazinium dyes, namely, phenosafranin (PSF) and safranin-T (ST), have been performed in protic and aprotic polar solvents. The studies reveal the formation of both J- and H-aggregates in concentrated solutions. The planarity of the phenazinium skeleton and the presence of a positive charge are attributed to be the driving force for this aggregation behavior. The aggregates are established to be dimers only. The positive inductive effect of the methyl substituents in safranin-T augments the aggregation process. The experiments reveal that for both dyes, the polar protic solvent favors the aggregation process more than the aprotic solvent.

  5. Phosphorescent Chemosensor Based on Iridium(III) Complex for the Selective Detection of Cu(II) Ion in Aqueous Acetonitrile

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyebin; Li, Yinan; Hyun, Myungho [Pusan National Univ., Busan (Korea, Republic of)


    Iridium(III) complex 1 containing two cyclo-metalating 2-phenylpyridine (ppy) ligands and one 2,2'-bipyridine ligand tethered with two DPA moieties by a methylene linker was prepared. Iridium(III) complex 1 was found to form 1:2 complex selectively with Cu(II) ion with the Stern-Volmer constant of 5.8 Χ 10{sup 4} M{sup -1}. Cu(II) ion has two sides. In one side, Cu(II) ion is an important cofactor in nearly 20 metalloenzymes and an essential micronutrient for all living systems. But, in other side, Cu(II) ion is one of significant metal pollutants and toxic to living cells if present in slightly high concentrations, causing neurodegenerative diseases such as Menkes and Wilson's disease. In this instance, the selective detection of Cu(II) ion in environment and in living systems is very important. Consequently, various fluorescent chemosensors for the highly sensitive and selective detection of Cu (II) ion have been developed.

  6. Bis[μ-1-(3,5-dichloropyridin-2-yl-2-(pyridin-3-ylmethylidenehydrazine]bis[(nitrato-κOsilver(I] acetonitrile disolvate

    Directory of Open Access Journals (Sweden)

    Ying Guo


    Full Text Available In the centrosymmetric binuclear title complex, [Ag2(NO32(C11H8Cl2N42]·2CH3CN, the AgI atom is four-coordinated and exhibits a highly distorted tetrahedral coordination sphere defined by three N atoms from two 1-(3,5-dichloropyridin-2-yl-2-(pyridin-3-ylmethylidenehydrazine ligands and one O atom from a nitrate anion. Intermolecular N—H...O hydrogen bonds link the complex molecules, resulting in a two-dimensional supramolecular structure parallel to (001.

  7. Electrochemistry in Near-Critical and Supercritical Fluids. 6. The Electrochemistry of Ferrocene and Phenazine in Acetonitrile between 25C and 300C. (United States)


    Prepared for Publication SD in Journal of Electroanalytical Chemistry The University of Texas at Austin Department of Chemistry Austin, Texas 78712...IS S,.PPLEMEINTARY NCTES Prepared for publication in the Journal of Electroanalytical Chemistry IS. K LY WORDS (Continue on reverse side if neceeesar...Journal of Electroanalytical Chemistry July 1987 2 I NTRODUCTI ON Previous reports from this laboratory have demonstrated that inorganic supercritical

  8. On the formation of radical dications of protonated amino acids in a "microsolution" of water or acetonitrile and their reactivity towards the solvent

    DEFF Research Database (Denmark)

    Sørensen, M; Forster, JS; Hvelplund, P


    in detail for A=Tyr and find that the first two reactions are unfavorable whereas the third one is favorable. However, energy is required for the formation of Tyr+* and SH+ from TyrH2+*(S) to overcome the Coulomb barrier, which renders the complex observable with a life-time larger than 5 micros...

  9. Crystal structure of bis[μ-bis(diphenylphosphanylmethane-κ2P:P′]-μ-chlorido-chlorido-1κCl-(1-phenylthiourea-2κSdisilver acetonitrile hemisolvate

    Directory of Open Access Journals (Sweden)

    Arunpatcha Nimthong-Roldán


    Full Text Available In the dinuclear title complex, [Ag2Cl2(C7H8N2S(C25H22P22]·0.5CH3CN, each AgI ion displays a distorted tetrahedral coordination geometry with two P atoms from two bis(diphenylphosphanylmethane (dppm ligands, one bridging chloride ion, one terminal chloride ion and one terminal S atom from the N,N′-phenylthiourea (ptu ligand. The dppm ligands and the bridging chloride ion force the two Ag atoms into close proximity, with a short Ag...Ag separation of 3.2064 (2 Å. In the crystal, complex molecules are linked by N—H...Cl hydrogen bonds forming a dimer. The dimers are linked via weak C— H...Cl hydrogen bonds forming a two-dimensional supramolecular architecture in the yz plane. In addition, an intramolecular N—H...Cl hydrogen bond is observed.

  10. Tetrakis[μ-2-(methoxycarbonylbenzoato-κ2O1:O1′]bis[(acetonitrile-κNcopper(II](Cu—Cu

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    Jing-lin Wang


    Full Text Available In the binuclear copper(II title complex, [Cu2(C9H7O44(C2H3N2], an inversion centre is situtated at the mid-point of the Cu—Cu bond. The CuII atom together with its four coordinated O atoms are in a distorted planar square arrangement while the nitrogen and the other CuII atom are located in apical positions. The whole molecule looks like a paddle-wheel. In the crystal, chains are assembled along the b axis through C—H...O hydrogen bonds and slipped π–π interactions between the benzene rings of neighbouring molecules [centroid–centroid distance = 3.6929 (3 Å and slippage = 0.641 (1 Å].

  11. Electronic, infrared, mass, 1H NMR spectral studies of the charge-transfer complexes of sulphonamide drugs with π-acceptors in acetonitrile (United States)

    Frag, Eman Y.; Mohamed, Gehad G.


    The rapid interaction between sulphonamides (sulphamethoxazole (SMZ), sulphaguanidine (SGD), sulphaquinoxaline sodium (SQX) and sulphadimidine sodium (SDD)) as n-electron donors with the 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid, p-CLA) as π-acceptors resulted in the formation of 1:1 charge-transfer complexes as the final products with the formula [(drug) (acceptor)]. The final products of the reactions have been isolated and characterized using FT-IR, 1H NMR, mass spectroscopy and elemental analyses as well as photometric measurements and thermogravimetric analysis (TG). The stoichiometry and apparent formation constants of the complexes formed were determined by applying the conventional spectrophotometric molar ratio method.

  12. 间歇萃取精馏分离乙腈-甲苯共沸体系%Separation of Acetonitrile-Toluene Mixture by Batch Extractive Distillation

    Institute of Scientific and Technical Information of China (English)

    崔现宝; 周金波; 张宾山; 冯天扬; 杨志才



  13. Separation of Acetonitrile-Water Mixture by Batch Extractive Distillation%间歇萃取精馏分离乙腈-水体系

    Institute of Scientific and Technical Information of China (English)

    周金波; 崔现宝; 董炳利; 王艳飞; 程中克


    选择乙二醇为分离乙腈-水体系的萃取剂,在压力0.101 MPa条件下,测定了乙腈-乙二醇物系的汽液平衡数据.采用Wilson模型对试验数据进行关联,得到Wilson模型参数,α1=5 683.6,α1,3=576.4(下标1代表乙腈,3代表乙二醇),关联的计算结果和试验结果的最大偏差为0.0157.测定了乙二醇存在下乙腈-水物系的汽液平衡数据,试验结果表明乙二醇做萃取剂能够消除乙腈-水物系的共沸点.进行了乙腈-水物系的间歇萃取精馏试验,回流比为2.0,萃取剂流量与回流量之比(溶剂比)为4.1,塔顶产品中乙腈的摩尔分数x达到0.988,乙腈的回收率为75%.应用Chemcad软件考察溶剂比和回流比对产品纯度及塔顶产品量的影响,确定适宜溶剂比为3.0,其回流比值在0.5~2.0之间.

  14. Crystal Structure of catena-[(Tetrakis-μ2-acetato-μ2-4,4'-bipyridine) dicopper(Ⅱ)] Acetonitrile Solvate

    Institute of Scientific and Technical Information of China (English)

    WEN Yi-Hang; HE Yin-Hua; FENG Yun-Long; NG Seik Weng


    The title compound,[Cu2(CH3COO)4(C8H10N2)]n·nCH3CN1 (C8H10N2,4,4'-bipy = 4,4'-bipyridine),has been solvothermally synthesized in CH3CN and characterized by X-ray diffraction.The crystal is of monoclinic,space group Cc with a = 22.626(6),b = 14.012(4),c =15.106(4) (A),β = 107.610(3)°,V = 4565(2) (A)3,C20H23Cu2N3O8,Mr = 560.49,Z = 8,Dc = 1.631 g/cm3,μ = 1.914 mm-1,Flack parameter = 0.48(1),F(000) = 2288,R = 0.042 and wR = 0.)98 for 8887 observed reflections (I > 2σ(I)).It consists of nearly linear one-dimensional chains [Cu2(CH3COO)4(C8H10N2)]n derived from paddle-wheel [Cu2(CH3COO)4] unit linked by 4,4'-bipy,and CH3CN as guest molecule regularly decorates between the chains.

  15. Characterization of p-Type CdTe Electrodes in Acetonitrile/Electrolyte Solutions. Nearly Ideal Behavior from Reductive Surface Pretreatments. (United States)


    spectra were obtained by interfacing a PAR Model 6001 photoacoustic spectrmter with a potentiostat. The photoacoustic sample cell was replaced by a single...underlying (bulk) CdTe; deconvolution of this rather broad (FHM -1.8 eV) set of bands yields two sets of bands separated by -1 eV, the difference... Code 413 Attn: Mr. Joe McCartney 800 North Quincy Street San Diego, California 92152 Arlington, Virginia 22217 2 Naval Weapons Center ONR Pasadena

  16. Vitamin D analysis in plasma by high performance liquid chromatography (HPLC) with C30 reversed phase column and UV detection - easy and acetonitrile-free

    DEFF Research Database (Denmark)

    Hymøller, Lone; Jensen, Søren Krogh


    Two physiologically important forms of vitamin D exist: vitamin D2 and vitamin D3, which by liver based hydroxylase enzymes are converted to 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3, respectively. These hydroxylated metabolites of vitamin D are measured in plasma to assess the vtamin D status...... detection at 265nm for quantifying vitamin D2, vitamin D3, 25-hydroxyvitamin D2, and 25-hydroxyvitamin D3. The method proved versatile with respect to plasma lipid content, sample amount, and plasma concentration of the vitamin D metabolites as it was tested using plasma from six different species: cattle...... material® 972 “Vitamin D in human serum” from the National Institute of Standards and Technology (NIST) (Gaithersburg, USA) the results for 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 concentrations were within the boundaries provided by NIST, reflected by Z-scores between 0.1 and 0.9....

  17. Trichlorido[4-methoxy-2,6-bis(2-pyrimidin-2-yl-κNphenyl-κC1]platinum(IV acetonitrile monosolvate

    Directory of Open Access Journals (Sweden)

    Yang Wu


    Full Text Available In the title complex, [Pt(C15H11N4OCl3]·CH3CN, the PtIV ion adopts a distorted octahedral coordination geometry defined by a tridentate cyclometalated NCN ligand and three Cl atoms. In the crystal, individual molecules are aggregated into a three-dimensional network by C—H...Cl hydrogen-bonding interactions and π–π stacking interactions between the tridentate ligands, the shortest ring centroid–centroid distance being 3.613 Å.

  18. 75 FR 53867 - Additions to Listing of Exempt Chemical Mixtures (United States)


    ...% acetonitrile), dimethylformamide, ethylene glycol, isopropanol, methanol, methanol/water (50:50), methanol..., acetonitrile, acetonitrile: water (>= 50% acetonitrile), dimethylformamide, ethylene glycol, isopropanol...), dimethylformamide, ethylene glycol, isopropanol, methanol, methanol/water (50:50), methanol/dimethyl sulfoxide...

  19. 乙腈体系中2'-萘乙酮激发三重态性质的激光光解研究%Laser- flash photolysis studies of 2'-acetonaphthone in acetonitrile solution

    Institute of Scientific and Technical Information of China (English)



  20. β-胡萝卜素在乙腈体系中的激光光解研究%The Triplet Properties of β-Carotene in Acetonitrile Solution: A Laser Flash Photolysis Study

    Institute of Scientific and Technical Information of China (English)

    张兆霞; 赵红卫; 朱红平; 郝淑梅; 王文锋; 李文新; Suppiah Navaratnam


    利用纳秒级激光光解瞬态吸收光谱装置,研究了以乙腈作为溶剂,以2-萘乙酮作为敏化剂的体系在355nm激光作用下敏化产生β-胡萝卜素激发三重态的机制,并进一步研究了β-胡萝卜素激发三重态的性质.研究显示2-萘乙酮和β-胡萝卜素的二元体系在355 nm激光作用下,2-萘乙酮首先被激发为其激发三重态(420 nm),2-萘乙酮激发三重态与β-胡萝卜素发生激发能转移,产生β-胡萝卜素激发三重态(510 nm).通过激发能转移的方法测得了β-胡萝卜素激发三重态在最大吸收波长510 nm处的摩尔消光系数为23 000 L·mol-1·cm-1.改变β-胡萝卜素的浓度测得了其激发三重态在乙腈体系中的衰变反应速率常数6.5×104s-1,其在乙腈体系中的三重态寿命为15.6μs.同时获得了激发态2-萘乙酮与β-胡萝卜素之间激发能转移反应的速率常数1-5×1010L·mol-1·s-1.

  1. Kinetic study on Michael-type reactions of β-nitrostyrenes with cyclic secondary amines in acetonitrile: transition-state structures and reaction mechanism deduced from negative enthalpy of activation and analyses of LFERs. (United States)

    Um, Ik-Hwan; Kang, Ji-Sun; Park, Jong-Yoon


    A kinetic study is reported for the Michael-type reactions of X-substituted β-nitrostyrenes (1a-j) with a series of cyclic secondary amines in MeCN. The plots of pseudo-first-order rate constant k(obsd) vs [amine] curve upward, indicating that the reactions proceed through catalyzed and uncatalyzed routes. The dissection of k(obsd) into Kk2 and Kk3 (i.e., the rate constants for the uncatalyzed and catalyzed routes, respectively) revealed that Kk3 is much larger than Kk2, implying that the reactions proceed mainly through the catalyzed route when [amine] > 0.01 M. Strikingly, the reactivity of β-nitrostyrene (1g) toward piperidine decreases as the reaction temperature increases. Consequently, a negative enthalpy of activation is obtained, indicating that the reaction proceeds through a relatively stable intermediate. The Brønsted-type plots for the reactions of 1g are linear with β(nuc) = 0.51 and 0.61, and the Hammett plots for the reactions of 1a-j are also linear with ρX = 0.84 and 2.10 for the uncatalyzed and catalyzed routes, respectively. The reactions are concluded to proceed through six-membered cyclic transition states for both the catalyzed and uncatalyzed routes. The effects of the substituent X on reactivity and factors influencing β(nuc) and ρX obtained in this study are discussed.

  2. Crystal structure of tris(μ-bis{4-[(pyridin-2-ylmethylideneamino]phenyl}methane-κ4N,N′:N′′,N′′′dizinc tetrakis(tetrafluoridoborate acetonitrile trisolvate

    Directory of Open Access Journals (Sweden)

    Maria-Gabriela Alexandru


    Full Text Available The asymmetric unit of the title compound, [Zn2(C25H20N43](BF44·3CH3CN, consists of one dinuclear ZnII complex cation with a triple-helical [Zn2L3]4+ motif (L is bis{4-[(pyridin-2-ylmethylideneamino]phenyl}methane, four BF4− anions and three CH3CN solvent molecules. The Zn...Zn separation is 11.3893 (14 Å and the ligands wrap around the two ZnII atoms, forming a triple helix as defined by the Zn—N—N—Zn torsion angles of 104.05 (18, 99.06 (19 and 101.40 (19°. The Zn—N(pyridyl distances in the octahedral ZnN6 coordination sphere are in the range 2.128 (5–2.190 (5 Å and the Zn—N(imine distances are in the range 2.157 (5–2.277 (5 Å.

  3. Study on the conductivity and viscosity of [Bmim]PF6 in methanol or acetonitrile%[Bmim] PF6在甲醇和乙腈中的电导率和黏度研究

    Institute of Scientific and Technical Information of China (English)

    章国栋; 沈尧; 许映杰


    测定了298.15K条件下1-丁基-3-甲基眯唑六氟磷酸盐离子液体([Bmim]PF6)在甲醇和乙腈中的电导率和黏度,讨论了[Bmim]PF6/甲醇和[Bmim]PF6/乙腈体系的溶液性质.结果表明,在0~0.3mol/L的浓度范围内,[Bmim]PF6/甲醇和[Bmim]PF6/乙腈体系的电导率随[Bmim]PF6浓度的增加而增加,并且[Bmim]PF6在甲醇中的电导率高于在乙腈中的电导率,说明[Bmim]PF6在甲醇中更容易电离;[Bmim]PF6/甲醇和[Bmim]PF6/乙腈体系的摩尔电导率随浓度的增加而降低,采用Kohlrausch公式计算回归了[Bmim]PF6在甲醇以及乙腈中的无限稀释摩尔电导率(∧wm),其值分别为156.96和153.83 s·cm2·mol-1.由Jones-Dole方程计算回归了[Bmim]PF6在甲醇和乙腈中黏度B系数,其值分别为0.36813和0.63248,表明[Bmim]PF6在甲醇中的黏度小于在乙腈中的黏度,这与电导率实验的结果是一致的.

  4. Acid/base and hydrogen bonding effects on the proton-coupled electron transfer of quinones and hydroquinones in acetonitrile: Mechanistic investigation by voltammetry, {sup 1}H NMR and computation

    Energy Technology Data Exchange (ETDEWEB)

    Alligrant, Timothy M. [Department of Chemistry, Virginia Commonwealth University, 1001 West Main St., P.O. Box 842006, Richmond, VA 23284 (United States); Hackett, John C. [Institute for Structural Biology and Drug Discovery, Virginia Commonwealth University, P.O. Box 980133, Richmond, VA 23219 (United States); Alvarez, Julio C., E-mail: jcalvarez2@vcu.ed [Department of Chemistry, Virginia Commonwealth University, 1001 West Main St., P.O. Box 842006, Richmond, VA 23284 (United States)


    This report seeks to address the role of hydrogen bonding with Bronsted acids and bases in proton-coupled electron transfer (PCET) as it pertains to concerted or stepwise pathways of quinone (Q) and hydroquinone (QH{sub 2}) electrochemistry. This study was performed using a series of techniques that included cyclic voltammetry (CV), digital simulations, computational chemistry and {sup 1}H NMR. Hydrogen bonding was inferred by a decrease in diffusion coefficient (D) values measured using a pulsed gradient echo- (PGE-) {sup 1}H NMR technique. Changes of 40.8% and 37.9% in D values were only noted after the addition of two equivalents of acetate to 1,4-hydroquinone (1,4-QH{sub 2}) and catechol (1,2-QH{sub 2}), respectively. In contrast, the D values for the addition of selected amines (pyridine, N,N-diisopropylethylamine and triethylamine) changed only 3.2% on average. Quantum mechanical calculations were conducted to determine the pK{sub a} of all quinoid species to serve as a starting point for the determination of equilibrium constants in voltammetric simulations. Simulations indicate that 1,4-benzoquinone undergoes stepwise electron-proton transfer upon addition of acetic acid, N-ethyldiisopropylammonium perchlorate and pyridinium nitrate and were simulated without the presence of hydrogen bonds. The QH{sub 2} compounds show stepwise proton-electron transfers after addition of the both the conjugate amines and acetate.

  5. [3,3′-Bis(1-naphthylmethyl-1,1′-(2,2′-oxydiethylenebis(imidazol-2-ylidene]mercury(II bis(hexafluoridophosphate acetonitrile solvate

    Directory of Open Access Journals (Sweden)

    Gui-Ying Dong


    Full Text Available In the title compound, [Hg(C32H30N4O](PF62·CH3CN, the mercury(II ion is coordinated by two carbene C atoms [Hg—C = 2.060 (6 and 2.066 (6 Å] and one ether O atom [Hg—O = 2.561 (5 Å] in a distorted T-shaped geometry with a C—Hg—C angle of 166.3 (3°. One hexafluoridophosphate anion is rotationally disordered between two orientations with an approximate ratio of 2:1. The crystal packing exhibits weak intermolecular C—H...F and C—H...N interactions.

  6. {3,3′-Bis[(anthracen-9-ylmethyl]-1,1′-[(ethane-1,2-diyldioxybis(ethane-1,2-diyl]bis(imidazol-2-ylidene}mercury(II bis(hexafluoridophosphate acetonitrile disolvate

    Directory of Open Access Journals (Sweden)

    Di-Si Bai


    Full Text Available In the title compound, [Hg(C42H38N4O2](PF62·2CH3CN, the HgII cation lies on a twofold axis which is also the internal symmetry element of the complete cationic complex. The HgII cation is coordinated by two symmetry-related C(carbene atoms [Hg—C = 2.058 (9 Å] in a nearly linear geometry, with a C—Hg—C angle of 175.8 (5°. There are weak intermolecular C—H...F interactions in the crystal packing between an F atom of a hexafluoridophosphate anion and a –CH2– group of the bis-N-heterocyclic carbene ligand.

  7. (μ-4-Bromo-3,5-dimethylpyrazolato-κ2N1:N2-μ-chlorido-bis[bis(4-bromo-3,5-dimethylpyrazole-κN2chloridocopper(II] acetonitrile monosolvate

    Directory of Open Access Journals (Sweden)

    Yanhui Xu


    Full Text Available In the title dinuclear complex, [Cu2(C5H6BrN2Cl3(C5H7BrN24]·CH3CN, both CuII ions are in slightly distorted square-pyramidal coordination geometries. The basal planes are defined by three N atoms from three 4-bromo-3,5-dimethylpyrazolate ligands, one of which is bridging, and one Cl ligand. A bridging Cl ligand forms the apical site for both CuII ions. In the crystal, N—H...Cl hydrogen bonds connect complex molecules into chains along [100]. Intramolecular N—H...Cl hydrogen bonds are also observed.

  8. (4′-Ferrocenyl-2,2′:6′,2′′-terpyridine-κ3N1,N1′,N1′′(1,10-phenanthroline-κ2N,N′zinc(II bis(perchlorate acetonitrile monosolvate

    Directory of Open Access Journals (Sweden)

    Si-Ping Tang


    Full Text Available In the title complex, [FeZn(C5H5(C20H14N3(C12H8N2](ClO42·CH3CN, the ZnII atom is five-coordinated by a tridentate chelating 4′-ferrocenyl-2,2′:6′,2′′-terpyridine (fctpy ligand and a bidentate chelating 1,10-phenanthroline (phen ligand in a distorted square-pyramidal environment with a phen N atom located at the apical position [Zn—N = 2.259 (4 Å]. The terpyridyl motif in each fctpy ligand is coplanar, but the cyclopentadienyl ring is twisted by 9.5 (2° out of coplanarity with each central pyridine. The two cyclopentadienyl rings of the ferrocenyl group are almost eclipsed with a deviation of 4.5 (1°. In addition, intermolecular π–π interactions [centroid–centroid distance 3.753 (2 Å] are present between the cyclopentadienyl and outer pyridyl rings of the fctpy ligands. One of the perchlorate anions is equally disordered over two positions.

  9. 室温离子液体[Bmim]PF6的合成及其与乙腈体系的过量摩尔体积的研究%Synthesis of room-temperature ionic liquid [Bmim]PF6 and study on excess molar volumes of [Bmim]PF6 with acetonitrile

    Institute of Scientific and Technical Information of China (English)

    许映杰; 沈剑锋; 王奇伟; 林会


    合成了1-丁基-3-甲基六氟磷酸盐离子液体([Bmim]PF6),并用傅里叶红外光谱仪表征其结构.在25 ℃下,测定[Bmim]PF6-乙腈体系在全浓度范围内的过量摩尔体积(VE).二元混合体系的VE实验测定值为负值,表明[Bmim]PF6与乙腈之间以弱化学作用占主导;并且当[Bmim]PF6的摩尔分数x1=0.25时,VE出现极值,表明此时两者相互作用最大.

  10. Crystal structures of tris[1-oxopyridine-2-olato(1−]silicon(IV chloride chloroform-d1 disolvate, tris[1-oxopyridine-2-olato(1−]silicon(IV chloride acetonitrile unquantified solvate, and fac-tris[1-oxopyridine-2-thiolato(1−]silicon(IV chloride chloroform-d1 disolvate

    Directory of Open Access Journals (Sweden)

    Bradley M. Kraft


    Full Text Available The cations in the title salts, [Si(OPO3]Cl·2CDCl3, (I, [Si(OPO3]Cl·xCH3CN, (II, and fac-[Si(OPTO3]Cl·2CDCl3, (III (OPO = 1-oxo-2-pyridinone, C5H4NO2, and OPTO = 1-oxo-2-pyridinethione, C5H4NOS, have distorted octahedral coordination spheres. The first two structures contain the same cation and anion, but different solvents of crystallization led to different solvates and packing arrangements. In structures (I and (III, the silicon complex cations and chloride anions are well separated, while in (II, there are two C—H...Cl distances that fall just within the sum of the van der Waals radii of the C and Cl atoms. The pyridine portions of the OPO ligands in (I and (II are modeled as disordered with the planar flips of themselves [(I: 0.574 (15:0.426 (15, 0.696 (15:0.304 (15, and 0.621 (15:0.379 (15; (II: 0.555 (13:0.445 (13, 0.604 (14:0.396 (14 and 0.611 (13:0.389 (13], demonstrating that both fac and mer isomers are co-crystallized. In (II, highly disordered solvent, located in two independent channels along [100], was unable to be modeled. Reflection contributions from this solvent were fixed and added to the calculated structure factors using the SQUEEZE [Spek (2015. Acta Cryst. C71, 9–18] function of program PLATON, which determined there to be 54 electrons in 225 Å3 accounted for per unit cell (25 electrons in 109 Å3 in one channel, and 29 electrons in 115 Å3 in the other. In (I and (II, all species lie on general positions. In (III, all species are located along crystallographic threefold axes.

  11. Crystal structures of tris-[1-oxo-pyridine-2-olato(1-)]silicon(IV) chloride chloro-form-d 1 disolvate, tris-[1-oxo-pyridine-2-olato(1-)]silicon(IV) chloride aceto-nitrile unqu-anti-fied solvate, and fac-tris-[1-oxo-pyridine-2-thiol-ato(1-)]silicon(IV) chloride chloro-form-d 1 disolvate. (United States)

    Kraft, Bradley M; Brennessel, William W; Ryan, Amy E; Benjamin, Candace K


    The cations in the title salts, [Si(OPO)3]Cl·2CDCl3, (I), [Si(OPO)3]Cl·xCH3CN, (II), and fac-[Si(OPTO)3]Cl·2CDCl3, (III) (OPO = 1-oxo-2-pyridin-one, C5H4NO2, and OPTO = 1-oxo-2-pyridine-thione, C5H4NOS), have distorted octa-hedral coordination spheres. The first two structures contain the same cation and anion, but different solvents of crystallization led to different solvates and packing arrangements. In structures (I) and (III), the silicon complex cations and chloride anions are well separated, while in (II), there are two C-H⋯Cl distances that fall just within the sum of the van der Waals radii of the C and Cl atoms. The pyridine portions of the OPO ligands in (I) and (II) are modeled as disordered with the planar flips of themselves [(I): 0.574 (15):0.426 (15), 0.696 (15):0.304 (15), and 0.621 (15):0.379 (15); (II): 0.555 (13):0.445 (13), 0.604 (14):0.396 (14) and 0.611 (13):0.389 (13)], demonstrating that both fac and mer isomers are co-crystallized. In (II), highly disordered solvent, located in two independent channels along [100], was unable to be modeled. Reflection contributions from this solvent were fixed and added to the calculated structure factors using the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] function of program PLATON, which determined there to be 54 electrons in 225 Å(3) accounted for per unit cell (25 electrons in 109 Å(3) in one channel, and 29 electrons in 115 Å(3) in the other). In (I) and (II), all species lie on general positions. In (III), all species are located along crystallographic threefold axes.

  12. Formation of CTC by 2-chloro-5-methoxyl-p-benzoquinone and tertiary amines in acetonitrile%胺与2-氯-5-甲氧基对苯醌在乙腈中形成电荷转移络合物的研究

    Institute of Scientific and Technical Information of China (English)

    郭洪玲; 郭小永; 严宝珍



  13. Trifluoromethanesulfonic acid promoted Dakin-West reaction: An efficient and convenient synthesis of -acetamido ketones

    Indian Academy of Sciences (India)

    Ravindra M Kumbhare; Madabhushi Sridhar


    Trifluoromethanesulfonic acid promoted efficient condensation of an aromatic aldehyde with an acetophenone and acetonitrile in the presence of acetylchloride as an activator producing -acetamido carbonyl compounds is described.

  14. Organometallic Trinuclear Niobium Cluster Complex in Aqueous Solution: Synthesis and Characterization of Niobium Complexes Containing Nb-3(mu-eta(2):eta(2) (perpendicular to)-NCCH3)(mu(2)-O)(3)(6+) Cluster Core

    DEFF Research Database (Denmark)

    Joensen, H.A.N.; Hansson, G. K.; Kozlova, S.G.


    The synthesis and characterization of an organometallic trinuclear oxo-bridged niobium cluster complex with perpendicularly coordinated mu(3)eta(2):eta(2)(perpendicular to)-acetonitrile ligand in aqueous solution is reported. Reaction of NbCl5 in acetonitrile with aluminum under argon followed by...

  15. Infrared Study of Solvent-Solute Interactions of 1-Substituted 2-Pyrrolidinones and Related Compounds

    NARCIS (Netherlands)

    Perjéssy, A.; Engberts, J.B.F.N.


    The wavenumbers of the carbonyl stretching vibrations of 2-pyrrolidinone (P), 1-methyl-2-pyrrolidinone (MP), 1-isopropyl-2-pyrrolidinone (IPP), 1-(2-hydroxyethyl)-2-pyrrolidinone (HEP), 2-oxobenzothiazole (OBT), and 3-octyl-2-oxobenzothiazole (OOBT) were measured in n-hexane/CDCl3, acetonitrile/D2O,

  16. The Solvent Mixture Sensitivity of Carbonyl Stretching Frequencies of 2-Pyrrolidinones and Related Compounds

    NARCIS (Netherlands)

    Perjessy, A.; Engberts, J.B.F.N.; Blandamer, M.J.


    The carbonyl stretching frequencies of 1-substituted 2-pyrrolidinones and related compounds were measured in binary mixtures of hexane-CDCl3 and acetonitrile-D2O and plotted against the mole fraction of the less polar co-solvent The v(C=O) vs. mole fraction correlations enabled to recognize and assi

  17. Spectrally resolved femtosecond photon echo spectroscopy of astaxanthin (United States)

    Kumar, Ajitesh; Karthick Kumar, S. K.; Gupta, Aditya; Goswami, Debabrata


    We have studied the coherence and population dynamics of Astaxanthin solution in methanol and acetonitrile by spectrally resolving their photon echo signals. Our experiments indicate that methanol has a much stronger interaction with the ultrafast dynamics of Astaxanthin in comparison to that of acetonitrile.

  18. Polyphenols are responsible for the proapoptotic properties of pomegranate juice on leukemia cell lines. (United States)

    Dahlawi, Haytham; Jordan-Mahy, Nicola; Clench, Malcolm; McDougall, Gordon J; Maitre, Christine Lyn


    Pomegranates have shown great promise as anti-cancer agents in a number of cancers including clinical trials in prostate cancer. We have previously shown pomegranate juice (PGJ) induced apoptosis and preferentially alters the cell cycle in leukemia cell lines compared with nontumor control cells. However, the agents responsible have not yet been fully elucidated. Treatment of four leukemia cell lines with five fractions obtained from PGJ by solid phase extraction demonstrated that only the acetonitrile fractions decreased adenosine triphosphate (ATP) levels in all leukemia cell lines. Acetonitrile fractions also significantly activated caspase-3 and induced nuclear morphology characteristic of apoptosis. S phase arrest was induced by acetonitrile fractions which matched S phase arrest seen previously following whole PGJ treatments. The acetonitrile fractions contained higher phenol content than whole PGJ whereas only low levels of phenols were seen in any other fraction. Liquid chromatography mass spectrometry (LC-MS) analysis demonstrated that acetonitrile fractions were enriched in ellagitannins, ellagic acid, and hydroxycinnamic acid derivatives but depleted in anthocyanins. Individual treatments with identified compounds demonstrated that the ellagitannin: punicalagin was the most active and mimicked the responses seen following acetonitrile fraction treatment. Bioactive components within pomegranate were confined to the acetonitrile fraction of PGJ. The enrichment in ellagitannins and hydroxycinnamic acids suggest these may provide the majority of the bioactivities of PGJ. Individual treatments with compounds identified demonstrated that the ellagitannin: punicalagin was the most active agent, highlighting this compound as a key bioactive agent in PGJ.

  19. Morphology Control over the Organic Nanoparticles of 1,3-Diphenyl-5-(9-anthryl)-2-pyrazoline

    Institute of Scientific and Technical Information of China (English)

    奚璐; 肖德宝; 杨文胜; 姚建年; 张宝文


    The organic nanoparticles of a blue-light-emitting molecule, 1,3-diphenyl-5-(9-anthryl)-2-pyrazuline, were prepared by reprecipitation method using acetonitrile as the solvent for the molecular precursor. Three morphologies, spherical, doughnut-shaped and cubic, could be observed on the silicon substrate forthe nanoparfides by the volume-controlled addition of acetonitrile. The evolution of particle morphology as a function of acetonitrile addition was attributed to the variation of the growth habits of the particles in the different environment. The nanoparticles exhibit the novel photoluminescence spectra as compared to those of monomer and the bulk crystals.

  20. Utility of 4-formylantipyrine in heterocyclic synthesis

    Directory of Open Access Journals (Sweden)

    Abdou O. Abdelhamid


    Full Text Available Pyrrolo[3,4-c]pyrazole-4,6(1H,5H-dione, pyrano[2,3-c]pyrazole-5-carbonitrile, pyrano[2,3-d]4-imidazolines, pyrido[2,1-b]benzimidazole, pyrido[2,1-b][1,3]benzoxazole, pyrido[2,1-b][1,3]benzothiazole and pyrido[2,1-b]quinazoline were synthesised from antipyrine derivatives with appropriate reagents such as maleimides, malononitrile, ethyl cyanoacetate, benzimidazole-2-acetonitrile, benzothiazole-2-acetonitrile, benzoxazol-2-acetonitrile, benzoylacetonitrile and other reagents. The newly synthesised compounds were established by elemental analysis, spectral data, and alternative synthetic routes whenever possible.

  1. A New Method of Separation of Four Benzodiazepines by RP-CEC

    Institute of Scientific and Technical Information of China (English)

    Jin Lan ZHANG; Tong Hui ZHOU


    A new method to separate diazepam, nitrazepam, estazolam, alprazolam was established on both C18 and C8 CEC columns.The influence of separation voltage, Tris concentration, column temperature and the percentage of acetonitrile on the resolution and retention behavior of four benzodiazepines was investigated.The results showed that the percentage of acetonitrile had the largest effect on the resolution and retention behavior of the four benzodiazepines.Other separation conditions had also effects on the resolution and retention behavior, but smaller than the concentration of acetonitrile.Optimum separation conditions were obtained to separate four benzodiazepines on C18 and C8 CEC columns.

  2. Development of a UPLC–MS/MS method for determining ɣ-hydroxybutyric acid (GHB) and GHB glucuronide concentrations in hair and application to forensic cases

    DEFF Research Database (Denmark)

    Wang, Xin; Johansen, Sys Stybe; Linnet, Kristian


    We present a series of forensic cases measuring concentrations in hair of γ-hydroxybutyric acid (GHB) and its glucuronide. The compounds were extracted from hair by incubation for 1.5 h in a 25:25:50 (v/v/v) mixture of methanol/acetonitrile/2 mM ammonium formate (8 % acetonitrile, pH 5.3). The co......We present a series of forensic cases measuring concentrations in hair of γ-hydroxybutyric acid (GHB) and its glucuronide. The compounds were extracted from hair by incubation for 1.5 h in a 25:25:50 (v/v/v) mixture of methanol/acetonitrile/2 mM ammonium formate (8 % acetonitrile, pH 5...

  3. Yttrium (III chloride catalyzed Mannich reaction: An efficient procedure for the synthesis of β-amino carbonyl compounds

    Directory of Open Access Journals (Sweden)

    Venkateswarlu Yekkirala


    Full Text Available Yttrium (III chloride catalyzed Mannich reaction of aldehydes with ketones and amines in acetonitrile at reflux temperature to give various β-amino carbonyl compounds in very good yields.

  4. DABCO-promoted facile and convenient synthesis of novel isoxazolyl-1H-2,3-pyrrole dicarboxylates

    Institute of Scientific and Technical Information of China (English)

    Rajanarendar Eligeti; Kishore Baireddy; Ramakrishna Saini


    Synthesis of isoxazolyl-1H-2,3-pyrrole dicarboxylate (4) was simply achieved by one-pot three component reaction of isoxazole amine (1) with diethyl acetylenedicarboxylate (DEAD) (2),and glyoxal (3),in acetonitrile catalyzed by diazabicyclo octane (DABCO).

  5. Electrolyte Effects on the Cyclic Voltammetry of TCNQ (Tetracyanoquinodimethane) and TCNE (Tetracyanoethylene). (United States)


    to form two radical anions. In this note we report a study by cyclic voltammetry of the reductions of TCNQ and TCNE to their radical anions and dianions at platinum and glassy carbon electrodes in acetonitrile.

  6. Bithiophene radical cation: Resonance Raman spectroscopy and molecular orbital calculations

    DEFF Research Database (Denmark)

    Grage, M.M.-L.; Keszthelyi, T.; Offersgaard, J.F.


    The resonance Raman spectrum of the photogenerated radical cation of bithiophene is reported. The bithiophene radical cation was produced via a photoinduced electron transfer reaction between excited bithiophene and the electron acceptor fumaronitrile in a room temperature acetonitrile solution a...

  7. Effect of some organic solvents on oxidative phosphorylation in rat liver mitochondria

    DEFF Research Database (Denmark)

    Syed, Muzeeb; Skonberg, Christian; Hansen, Steen Honoré


    The effect of acetone, acetonitrile, dimethyl sulfoxide (DMSO), ethanol and methanol on oxidative phosphorylation (ATP synthesis) in rat liver mitochondria has been studied. All the organic solvents inhibited the oxidative phosphorylation in a concentration dependent manner, but with differences...... in potencies. Among the tested organic solvents, acetonitrile and acetone were more potent than ethanol, methanol, and DMSO. There was no significant difference in oxidative phosphorylation, compared to controls, when the concentrations of acetone was below 1% (v/v), of acetonitrile below 2% (v/v), of DMSO...... below 10% (v/v), of ethanol below 5% or of methanol below 2%, respectively. There was complete inhibition of oxidative phosphorylation at 50% (v/v) of acetone, acetonitrile and ethanol. But in the case of DMSO and methanol there were some residual activities observed at the 50% concentration level. DMSO...

  8. Solvation Effects on Electronic Transitions

    DEFF Research Database (Denmark)

    Schwabe, Tobias; Olsen, Jógvan Magnus Haugaard; Sneskov, Kristian;


    The polarizable embedding (PE) approach, which combines quantum mechanics (QM) and molecular mechanics (MM), is applied to predict solvatochromic effects on excitation energies of several representative molecules in aqueous, methanol, acetonitrile, and carbon tetrachloride solutions. Good agreeme...

  9. Deprotection of oximes using urea nitrate under microwave irradiation

    Indian Academy of Sciences (India)

    P T Perumal; M Anniyappan; D Muralidharan


    A new mild and efficient method for the cleavage of oximes to carbonyl compounds using readily available urea nitrate in acetonitrile-water (95 : 5), under microwave irradiation within 2 min, in good yields is reported.

  10. Detailed insights into the retention mechanism of caffeine metabolites on the amide stationary phase in hydrophilic interaction chromatography. (United States)

    Guo, Yong; Shah, Rajan


    The amide phase was investigated using a wide range of acetonitrile content in the mobile phase in both the HILIC and RPLC modes. Using caffeine metabolites as the model compounds, the retention, thermodynamic and kinetic data was obtained under various mobile phase conditions and supported the previous postulation that there might be a transition of the predominant retention mechanism in relation to the acetonitrile content in HILIC. On the amide phase, hydrophilic partitioning seemed to be the predominant retention mechanism below 85% acetonitrile; and a different retention mechanism (presumably surface adsorption) made more and more significant contributions to the overall retention when the acetonitrile content reached above 85%. This study also provided more direct evidences to explain the effect of salt concentration on the retention of non-charged solutes in HILIC. In addition, the retention, thermodynamic and kinetic data suggest that the amide phase behaved very differently from the conventional C18 phase in the RPLC mode.

  11. Influence of salt ions on binding to molecularly imprinted polymers.


    Kempe, Henrik; Kempe, Maria


    Salt ions were found to have an influence on template binding to two model molecularly imprinted polymers (MIPs), targeted to penicillin G and propranolol, respectively, in water-acetonitrile mixtures. Water was detrimental to rebinding of penicillin G whereas propranolol bound in the entire water-acetonitrile range tested. In 100% aqueous solution, 3-M salt solutions augmented the binding of both templates. The effects followed the Hofmeister series with kosmotropic ions promoting the larges...

  12. Determination of resveratrol and its sulfate and glucuronide metabolites in plasma by LC-MS/MS and their pharmacokinetics in dogs


    Muzzio, Miguel; Huang, Zhihua; Hu, Shu-Chieh; Johnson, William D.; McCormick, David L.; Kapetanovic, Izet M.


    An analytical approach for the determination of trans-resveratrol (3,5,4′-trihydroxy-trans-stilbene) and its glucuronide and sulfate conjugates in dog plasma by LC-MS/MS (without enzymatic hydrolysis of the conjugates) was validated to support pre-clinical toxicological and pharmacological studies. The approach required two independent sample extractions and consequent instrument runs. Samples for resveratrol determination were prepared by protein precipitation with acetonitrile; acetonitrile...

  13. Low-temperature liquid-liquid extraction of phenols from aqueous solutions with hydrophilic mixtures of extractants (United States)

    Rudakov, O. B.; Khorokhordina, E. A.; Preobrazhenskii, M. A.; Rudakova, L. V.


    The volume ratios in acetonitrile-ethyl acetate (90 : 10, 95 : 5), acetonitrile-isopropanol-ethyl acetate (70 : 15 : 15, 80 : 5 : 15), and isopropanol-1-butanol (50 : 50) mixtures were determined. Their mixing with water (1 : 1) and storage at-10°C led to partitioning into two immiscible liquid phases without formation of the ice phase. The mixtures were shown to be useful as hydrophilic extractants in low-temperature liquidliquid extraction of phenol from aqueous solutions.

  14. 78 FR 40175 - Exempt Chemical Preparations Under the Controlled Substances Act (United States)


    ... 0.1 Glass vial: 1 mL........ 11/30/2012 mg/mL in Methanol (as free base). LGC Limited Iso-LSD... Acetonitrile. LGC Limited LSD (Lysergic Acid Glass vial: 1 mL........ 11/30/2012 Diethylamide) 0.025 mg/mL in Acetonitrile. LGC Limited LSD-D3 (Lysergic Acid Glass vial: 1 mL........ 11/30/2012 Diethylamide-D3) 0.025...

  15. 40 CFR Appendix II to Part 258 - List of Hazardous Inorganic and Organic Constituents (United States)


    ... Acenaphthylene Acetone 67-64-1 2-Propanone Acetonitrile; Methyl cyanide 75-05-8 Acetonitrile Acetophenone 98-86-2...)- beta-BHC 319-85-7 Cyclohexane, 1,2,3,4,5,6-hexachloro-,(1α,2β,3α,4β,5α,6β)- delta-BHC 319-86-8... 258—List of Hazardous Inorganic and Organic Constituents Common name 1 CAS RN 2 Chemical...

  16. A New Strategy for the Synthesis of 3-Acyl-coumarin Using Mesoporous Molecular Sieve MCM-41 as a Novel and Efficient Catalyst

    Institute of Scientific and Technical Information of China (English)



    3-Acyl-coumarins were obtained in high yields from ortho-hydroxybenzaldehydes and ethyl acetoacetate or ethyl benzoylacetate in acetonitrile in the presence of a catalytic amount of mesoporous molecular sieve MCM-41. 3-Acyl-coumarins were obtained in high yields from ortho-hydroxybenzaldehydes and ethyl acetoacetate or ethyl benzoylacetate in acetonitrile in the presence of a catalytic amount of mesoporous molecular sieve MCM-41.

  17. Feasibility of using gravimetry to measure excess adsorption effects of a binary solvent system in a reversed-phase high-performance liquid chromatography column. (United States)

    Loeser, Eric; Babiak, Stanislaw; Liu, Zhaoxia; Girgis, Michael; Drumm, Patrick


    A modified method for weighing HPLC columns filled with solvent is described. The method prevents the loss of traces of solvent from within the threads of the column. The method was tested by obtaining the weights of a C18 column filled with 10 different organic solvents, showing a standard deviation on the order of 0.1%. A plot of gross column weight versus solvent density showed excellent linearity. The method was then used to weigh a column filled with several acetonitrile-water mixtures. The gross column weights were lower than would have been predicted from the density of the acetonitrile-water mixtures. A likely explanation is the existence of an adsorbed acetonitrile-rich liquid on the surface of the C18 adsorbent, which caused the lower than expected weights due to the lower density of pure acetonitrile relative to the bulk mixtures. The volume of pure acetonitrile required for the observed weight discrepancy was calculated. Based on the surface area of the column adsorbent, values of micromoles acetonitrile per square meter of surface area were determined. The values showed reasonable agreement with values obtained from published adsorption isotherm studies. This suggests that pycnometry may be a useful technique for adsorption studies. The limitations of the technique are discussed.

  18. Modelling of the effect of solute structure and mobile phase pH and composition on the retention of phenoxy acid herbicides in reversed-phase high-performance liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Aschi, Massimiliano [Dipartimento di Chimica, Ingegneria Chimica e Materiali, Universita degli Studi di L' Aquila, Via Vetoio, 67010 Coppito, L' Aquila (Italy); D' Archivio, Angelo Antonio [Dipartimento di Chimica, Ingegneria Chimica e Materiali, Universita degli Studi di L' Aquila, Via Vetoio, 67010 Coppito, L' Aquila (Italy)], E-mail:; Mazzeo, Pietro; Pierabella, Mirko; Ruggieri, Fabrizio [Dipartimento di Chimica, Ingegneria Chimica e Materiali, Universita degli Studi di L' Aquila, Via Vetoio, 67010 Coppito, L' Aquila (Italy)


    A feed-forward artificial neural network (ANN) learned by error back-propagation is used to generate a retention predictive model for phenoxy acid herbicides in isocratic reversed-phase high-performance liquid chromatography. The investigated solutes (18 compounds), apart from the most common herbicides of this class, include some derivatives of benzoic acid and phenylacetic acid structurally related to phenoxy acids, as a whole covering a pK{sub a} range between 2.3 and 4.3. A mixed model in terms of both solute descriptors and eluent attributes is built with the aim of predicting retention in water-acetonitrile mobile phases within a large range of composition (acetonitrile from 30% to 70%, v/v) and acidity (pH of water before mixing with acetonitrile ranging between 2 and 5). The set of input variables consists of solute pK{sub a} and quantum chemical molecular descriptors of both the neutral and dissociated form, %v/v of acetonitrile in the mobile phase and pH of aqueous phase before mixing with acetonitrile. After elimination of redundant variables, a nine-dimensional model is identified and its prediction ability is evaluated by external validation based on three solutes not involved in model generation and by cross-validation. A multilinear counterpart in terms of the same descriptors is seen to provide a noticeably poorer retention prediction.

  19. Spectroscopic, thermodynamic, kinetic studies and oxidase/antioxidant biomimetic catalytic activities of tris(3,5-dimethylpyrazolyl)borate Cu(II) complexes. (United States)

    Shaban, Shaban Y; Ramadan, Abd El-Motaleb M; Ibrahim, Mohamed M; Mohamed, Mahmoud A; van Eldik, Rudi


    A series of copper(ii) complexes, viz. [Tp(MeMe)Cu(Cl)(H2O)] (), [Tp(MeMe)Cu(OAc)(H2O)] (), [Tp(MeMe)Cu(NO3)] () and [Tp(MeMe)Cu(ClO4)] () containing tris(3,5-dimethylpyrazolyl)borate (KTp(MeMe)), have been synthesized and fully characterized. The substitution reaction of with thiourea was studied under pseudo-first-order conditions as a function of concentration, temperature and pressure in methanol and acetonitrile as solvents. Two reaction steps that both depended on the nucleophile concentration were observed for both solvents. Substitution of coordinated methanol is about 40 times faster than the substitution of chloride. In acetonitrile, the rate constant for the displacement of coordinated acetonitrile was more than 20 times faster than the substitution of chloride. The reported activation parameters indicate that both reaction steps follow a dissociative mechanism in both solvents. On going from methanol to acetonitrile, the rate constant for the displacement of the solvent becomes more than 200 times faster due to the more labile acetonitrile, but the substitution mechanism remained to have a dissociative character. The antioxidant activities of were evaluated for superoxide dismutase (SOD), glutathione-s-transferase (GST0 and glutathione reduced (GSH-Rd) activity. and were found to show (p reaction rate depended linearly on the complex concentration, indicating a first-order dependence on the catalyst concentration.

  20. The use of molecular probes for the characterization of dispersions of functionalized silica nanoparticles. (United States)

    Arce, Valeria B; Bertolotti, Sonia G; Oliveira, Fernando J V E; Airoldi, Claudio; Gonzalez, Mónica C; Allegretti, Patricia E; Mártire, Daniel O


    Butoxylated silica nanoparticles (BSN) were prepared by esterification of the silanol groups of fumed silica nanoparticles with butanol and characterized by 13C and 29Si NMR and thermogravimetry. The molecular probes benzophenone (BP) and safranine-T were used to investigate the BSN suspensions in water:acetonitrile. Laser flash-photolysis experiments at lambda(exc)=266 nm performed with BSN suspended in acetonitrile:aqueous phosphate buffer supported previous results of our group obtained by time-resolved phosphorescence experiments and showed that only free and adsorbed excited triplet states of BP and diphenylketyl radicals contribute to the signals. The UV-vis spectroscopic and photophysical properties of safranine-T are strongly solvent-dependent. Thus, the analysis of the emission spectra and fluorescence lifetimes yielded information on the localization of this probe molecule in suspensions of BSN and of the bare silica nanoparticles. The values of the equilibrium constant for the adsorption of the ground-state safranine-T on the particles were found to be (9.2+/-0.8)x10(4), (7.2+/-0.8)x10(5), and (3.0+/-0.1)x10(4) for the BSN in 1:1 acetonitrile:water, SiO2 in 1:1 acetonitrile:water, and SiO2 in acetonitrile, respectively.

  1. Synthesis, characterization, and reactivity of furan- and thiophene-functionalized bis(n-heterocyclic carbene) complexes of iron(II)

    KAUST Repository

    Rieb, Julia


    The synthesis of iron(II) complexes bearing new heteroatom-functionalized methylene-bridged bis(N-heterocyclic carbene) ligands is reported. All complexes are characterized by single-crystal X-ray diffraction (SC-XRD), nuclear magnetic resonance (NMR) spectroscopy, and elemental analysis. Tetrakis(acetonitrile)-cis-[bis(o-imidazol-2-ylidenefuran)methane]iron(II) hexafluorophosphate (2a) and tetrakis(acetonitrile)-cis-[bis(o-imidazol-2-ylidenethiophene)methane]iron(II) hexafluorophosphate (2b) were obtained by aminolysis of [Fe{N(SiMe3)2}2(THF)] with furan- and thiophene-functionalized bis(imidazolium) salts 1a and 1b in acetonitrile. The SC-XRD structures of 2a and 2b show coordination of the bis(carbene) ligand in a bidentate fashion instead of a possible tetradentate coordination. The four other coordination sites of these distorted octahedral complexes are occupied by acetonitrile ligands. Crystallization of 2a in an acetone solution by the slow diffusion of Et2O led to the formation of cisdiacetonitriledi[ bis(o-imidazol-2-ylidenefuran)methane]iron(II) hexafluorophosphate (3a) with two bis(carbene) ligands coordinated in a bidentate manner and two cis-positioned acetonitrile molecules. Compounds 2a and 2b are the first reported iron(II) carbene complexes with four coordination sites occupied by solvent molecules, and it was demonstrated that those solvent ligands can undergo ligand-exchange reactions.

  2. Simultaneous determination of selected eicosanoids by reversed-phase HPLC method using fluorescence detection and application to rat and human plasma, and rat heart and kidney samples. (United States)

    Aghazadeh-Habashi, Ali; Asghar, Waheed; Jamali, Fakhreddin


    Eicosanoids are biologically active lipid-derived oxidative metabolites of arachidonic acid. We, herein, present an improved sensitive, selective and robust high performance liquid chromatography (HPLC)-fluorescence assay for simultaneous quantification of eicosanoids in human plasma and rat tissues. Aliquots of 200 μL of plasma or 30 mg of heart or kidney tissues were spiked with 16-hydroxydecanoic acid as internal standard, and extracted with anhydrous acetonitrile using solid phase cartridges. The eluted samples were dried, reconstituted in anhydrous acetonitrile and labeled with 2-(2,3-naphthalimino)ethyl-trifluoromethanesulphonate in the presence of saturated potassium fluoride solution in anhydrous acetonitrile and N,N-diiospropylethylamine as catalyst. The derivatized eicosanoids were extracted with anhydrous acetonitrile using solid phase cartridges. Chromatographic separation was achieved on a C18 reversed phase column using gradient mobile phase of 0.05% of formic acid:acetonitrile:water at 0.8 mL/min flow rate. The analytes were detected at excitation and emission wavelength of 260 and 396 nm, respectively. The assay was linear (r(2)≥ 0.98) in the concentration range of 0.01-2.5 μg/mL. The intra-day and inter-day coefficients variation was less than 19.8%. Using this assay, we were able to quantify arachidonic acid metabolites simultaneously in human and rat biological samples.

  3. Volatile compounds from leaves of the African spider plant (Gynandropsis gynandra) with bioactivity against spider mite (Tetranychus urticae)

    DEFF Research Database (Denmark)

    Nyalala, Samuel Odeyo; Petersen, Mikael Agerlin; Grout, Brian William Wilson


    Previous studies have demonstrated that Gynandropsis gynandra emits acetonitrile as a foliar volatile from intact plants and isolated leaves, and that this compound is an effective spider mite repellent. This study has used gas chromatography–mass spectrometry to investigate volatile compounds...... emitted from homogenised G. gynandra leaves to evaluate their tissue acetonitrile content and to look for other compounds that might be exploited for the management of spider mites. Acetonitrile was absent from the homogenised tissues of five lines of G. gynandra, studied over two seasons. Thirteen......, and a high constitutive content of them in roses may be of value in targeted plant breeding for enhanced insect resistance. The range of isothiocyanates found in G. gynandra accounts for the bitter taste of the leaves when used as a traditional vegetable in Eastern Africa and provides a target...

  4. Effects of acid concentration on intramolecular charge transfer reaction of 4-(azetidinyl) benzonitrile in solution

    Indian Academy of Sciences (India)

    Biswajit Guchhait; Tuhin Pradhan; Ranjit Biswas


    Effects of acid concentration on excited state intramolecular charge transfer reaction of 4-(azetidinyl) benzonitrile (P4C) in aprotic (acetonitrile and ethyl acetate) and protic (ethanol) solvents have been studied by means of steady state absorption and fluorescence, and time resolved fluorescence spectroscopic techniques. While absorption and fluorescence bands of P4C have been found to be shifted towards higher energy with increasing acid concentration in acetonitrile and ethyl acetate, no significant dependence has been observed in ethanolic solutions. Reaction rate becomes increasingly slower with acid concentration in acetonitrile and ethyl acetate. In contrast, acid in ethanolic solutions does not produce such an effect on reaction rate. Time-dependent density functional theory calculations have been performed to understand the observed spectroscopic results.

  5. Direct-immersion solid-phase microextraction coupled to fast gas chromatography mass spectrometry as a purification step for polycyclic aromatic hydrocarbons determination in olive oil. (United States)

    Purcaro, Giorgia; Picardo, Massimo; Barp, Laura; Moret, Sabrina; Conte, Lanfranco S


    The aim of the present work was to optimize a preparation step for polycyclic aromatic hydrocarbons in a fatty extract. Solid-phase microextraction is an easy preparation technique, which allows to minimize solvent consumption and reduce sample manipulation. A Carbopack Z/polydimethylsiloxane fiber, particularly suitable for extraction of planar compounds, was employed to extract polycyclic aromatic hydrocarbons from a hexane solution obtained after a previous extraction with acetonitrile from oil, followed by a liquid-liquid partition between acetonitrile and hexane. The proposed method was a rapid and sensitive solution to reduce the interference of triglycerides saving the column life and avoiding frequent cleaning of the mass spectrometer ion source. Despite the non-quantitative extraction of polycyclic aromatic hydrocarbons from oil using acetonitrile, the signal-to-noise ratio was significantly improved obtaining a limit of detection largely below the performance criteria required by the European Union legislation.

  6. Purification of human brain metallothionein by organic and reversed-phase high-performance liquid chromatography under acidic conditions. (United States)

    Cartel, N J


    A simplified high-performance liquid chromatographic method for the detection of metallothioneins, notably metallothionein-III, has been developed. In order to purify metallothionein, differential acetone precipitation at 50% (v/v) and at 80% (v/v) was employed on a 20% normal human brain homogenate. The reconstituted pellet was injected into a C18 microbore reversed-phase HPLC column, equilibrated with 0.1% trifluoroacetic acid, and developed at a flow-rate of 800 microliter/min with a linear gradient from 0% to 60% acetonitrile in 0.094% trifluoroacetic acid for 60 min. Western blots indicated that metallothioneins-I and II eluted at 16% acetonitrile and metallothionein-III eluted at 37% acetonitrile.

  7. Validação de método analítico livre de acetonitrila para análise de microcistinas por cromatografia líquida de alta eficiência

    Directory of Open Access Journals (Sweden)

    Sérvio Túlio Alves Cassini


    Full Text Available Blooms of cyanobacteria represent a public health risk due to their cyanotoxins such as microcystins. Liquid chromatography techniques to separate and quantify microcystins invariably use acetonitrile as the organic component of the mobile phase. The price and availability of acetonitrile together with its elevated toxicity encourage the validation of acetonitrile-free methods of microcystin analysis. In this work, methanol was employed as the organic solvent of the mobile phase and the validation method was performed with different environmental water samples. The method showed limits of detection between 0.17 and 0.25 µg/L and of quantification between 0.55 and 0.82 µg/L for the microcystin variants: -RR, -YR, -LR, -LA.

  8. Polymer Conformation near the Critical Demixing Point of a Binary Solution (United States)

    He, Lilin; Cheng, Gang; Melnichenko, Yuri


    We have used Contrast Matching Small Angle Neutron Scattering (CMSANS) to probe directly the conformation change of polyethylene glycerol (PEO) chains in the critical demixing region of Acetonitrile-d3 in (D2O + H2O) at concentration of the components corresponding to zero-average contrast condition. The d-PEO and h-PEO were mixed to match the scattering length density (SLD) of the critical liquid solution, which allowed us to extract single-chain dimension of polymer molecules in the aggregates near the critical point of the solvent. A non-monotonic variation of Rg was detected as temperature approached the critical temperature of phase demixing of acetonitrile- water solution, which was attributed to the interaction asymmetry of the solvent molecules with polymers predicted by Brochard and de Gennes two decades ago. To our best knowledge, this is the first direct experimental evidence supporting this prediction.

  9. The examination of berberine excited state by laser flash photolysis (United States)

    Cheng, Lingli; Wang, Mei; Zhao, Ping; Zhu, Hui; Zhu, Rongrong; Sun, Xiaoyu; Yao, Side; Wang, Shilong


    The property of the excited triplet state of berberine (BBR) was investigated by using time-resolved laser flash photolysis of 355 nm in acetonitrile. The transient absorption spectra of the excited triplet BBR were obtained in acetonitrile, which have an absorption maximum at 420 nm. And the ratio of excitation to ionization of BBR in acetonitrile solvent was calculated. The self-decay and self-quenching rate constants, and the absorption coefficient of 3BBR* were investigated and the excited state quantum yield was determined. Furthermore utilizing the benzophenone (BEN) as a triplet sensitizer, and the β-carotene (Car) as an excited energy transfer acceptor, the assignment of 3BBR* was further confirmed and the related energy transfer rate constants were also determined.

  10. Effect of some organic solvents on oxidative phosphorylation in rat liver mitochondria: Choice of organic solvents. (United States)

    Syed, Muzeeb; Skonberg, Christian; Hansen, Steen Honoré


    The effect of acetone, acetonitrile, dimethyl sulfoxide (DMSO), ethanol and methanol on oxidative phosphorylation (ATP synthesis) in rat liver mitochondria has been studied. All the organic solvents inhibited the oxidative phosphorylation in a concentration dependent manner, but with differences in potencies. Among the tested organic solvents, acetonitrile and acetone were more potent than ethanol, methanol, and DMSO. There was no significant difference in oxidative phosphorylation, compared to controls, when the concentrations of acetone was below 1% (v/v), of acetonitrile below 2% (v/v), of DMSO below 10% (v/v), of ethanol below 5% or of methanol below 2%, respectively. There was complete inhibition of oxidative phosphorylation at 50% (v/v) of acetone, acetonitrile and ethanol. But in the case of DMSO and methanol there were some residual activities observed at the 50% concentration level. DMSO showed least effect on oxidative phosphorylation with an IC50 value of 13.3±1.1% (v/v), followed by methanol (IC50 value 8.3±1.0), ethanol (IC50 value 4.6±1.1), acetone (IC50 value 4.3±1.0) and finally acetonitrile (IC50 value 2.1±1.0). All the organic solvents showed modulatory effects on 2,4-dinitrophenol (DNP) mediated inhibition of oxidative phosphorylation with potentiation of the action of DNP. Acetonitrile showed the highest potentiation effect followed by acetone, ethanol, methanol, and DMSO in presence of DNP. The use of organic solvents for investigation of the effects of compounds on oxidative phosphorylation in mitochondria should therefore include the use of relevant concentrations of the organic solvent in order to validate the contribution.

  11. Stable Isotope-Assisted Evaluation of Different Extraction Solvents for Untargeted Metabolomics of Plants

    Directory of Open Access Journals (Sweden)

    Maria Doppler


    Full Text Available The evaluation of extraction protocols for untargeted metabolomics approaches is still difficult. We have applied a novel stable isotope-assisted workflow for untargeted LC-HRMS-based plant metabolomics , which allows for the first time every detected feature to be considered for method evaluation. The efficiency and complementarity of commonly used extraction solvents, namely 1 + 3 (v/v mixtures of water and selected organic solvents (methanol, acetonitrile or methanol/acetonitrile 1 + 1 (v/v, with and without the addition of 0.1% (v/v formic acid were compared. Four different wheat organs were sampled, extracted and analysed by LC-HRMS. Data evaluation was performed with the in-house-developed MetExtract II software and R. With all tested solvents a total of 871 metabolites were extracted in ear, 785 in stem, 733 in leaf and 517 in root samples, respectively. Between 48% (stem and 57% (ear of the metabolites detected in a particular organ were found with all extraction mixtures, and 127 of 996 metabolites were consistently shared between all extraction agent/organ combinations. In aqueous methanol, acidification with formic acid led to pronounced pH dependency regarding the precision of metabolite abundance and the number of detectable metabolites, whereas extracts of acetonitrile-containing mixtures were less affected. Moreover, methanol and acetonitrile have been found to be complementary with respect to extraction efficiency. Interestingly, the beneficial properties of both solvents can be combined by the use of a water-methanol-acetonitrile mixture for global metabolite extraction instead of aqueous methanol or aqueous acetonitrile alone.

  12. Development of liquid chromatographic method for the analysis of dabigatran etexilate mesilate and its ten impurities supported by quality-by-design methodology. (United States)

    Pantović, Jasmina; Malenović, Anđelija; Vemić, Ana; Kostić, Nađa; Medenica, Mirjana


    In this paper, the development of reversed-phase liquid chromatographic method for the analysis of dabigatran etexilate mesilate and its ten impurities supported by quality by design (QbD) approach is presented. The defined analytical target profile (ATP) was the efficient baseline separation and the accurate determination of the investigated analytes. The selected critical quality attributes (CQAs) were the separation criterions between the critical peak pairs because the mixture complexity imposed a gradient elution mode. The critical process parameters (CPPs) studied in this research were acetonitrile content at the beginning of gradient program, acetonitrile content at the end of gradient program and the gradient time. Plan of experiments was defined by Box-Behnken design. The experimental domains of the three selected factors x1--content of the acetonitrile at the start of linear gradient, x2--content of the acetonitrile at the end of linear gradient and x3--gradient time (tG) were [10%, 30%], [48%, 60%] and [8 min, 15 min], respectively. In order to define the design space (DS) as a zone where the desired quality criteria is met providing also the quality assurance, Monte Carlo simulations were performed. The uniform error distribution equal to the calculated standard error was added to the model coefficient estimates. Monte Carlo simulation included 5000 iterations in each of 3969 defined grid points and the region having the probability π ≥ 95% to achieve satisfactory values of all defined CQAs was computed. As a working point, following chromatographic conditions suited in the middle of the DS were chosen: 22% acetonitrile at the start of gradient program, 55.5% acetonitrile at the end of gradient program end and the gradient time of 11.5 min. The developed method was validated in order to prove its reliability.

  13. "Determination of mycophenolic acid in human plasma by high-performance liquid chromatography"


    "Mehdi Ahadi Barzoki; Mohammadreza Rouini; Kheirolla Gholami; Mahboob Lessan-Pezeshki; Saeed Rezaee


    A simple, sensitive and reproducible HPLC method is presented for determination of mycophenolic acid(MPA) in human plasma. Samples were prepared after precipitation of the plasma protein by addition of acetonitrile and naproxen was used as internal standard (I.S.). Separation was performed by reversedphase HPLC, using a Hamilton PRP-C18 Column, 51% acetonitrile and 49% potassium phosphate buffer (20 mM) at pH 3.0 as mobile phase, flow rate of 1.0 ml/min, and UV detection at 215 nm. MPA and I....

  14. Estimation of Chlorpyriphos in its Formulation (Paraban 20% EC by Reversed-Phase HPLC

    Directory of Open Access Journals (Sweden)

    Deepti Joshi


    Full Text Available A method has been developed for estimation of active ingredient in chlorpyriphos formulation (Paraban 20% EC. The formulation was extracted in chloroform, dried and resuspended in acetonitrile. The cleanup was performed using C18 SPE cartridge. The active ingredient was estimated using 5 μm ODS-II column, mobile phase was acetonitrile: water (75:25 v/v and detection at 229nm. The efficiency of clean up method was found to be 95% and minimum limit of detection < 2.5ng. The detector response was linear with in concentration range 2.5ng – 50ng at RSD 1.42%.

  15. Simultaneous screening and quantification of 52 common pharmaceuticals and drugs of abuse in hair using UPLC-TOF-MS

    DEFF Research Database (Denmark)

    Nielsen, Marie Katrine Klose; Johansen, Sys Stybe; Dalsgaard, Petur Weihe


    An UPLC-TOF-MS method for simultaneous screening and quantification of 52 drugs in hair was developed and validated. The selected drugs represent the most common classes of pharmaceuticals and drugs of abuse such as amphetamines, analgesics, antidepressants, antipsychotics, benzodiazepines, cocaine......, ketamine and opioids. Hair samples were extracted with methanol:acetonitrile:ammonium formate (2 mM, 8% acetonitrile, pH 5.3) overnight at 37 degrees C. The target drugs were separated and quantified using a Waters ACQUITY UPLC coupled to a Waters Micromass LCT Premier XE Time-of-Flight mass spectrometer...

  16. Resorcarene-based receptor: versatile behavior in its interaction with heavy and soft metal cations. (United States)

    Danil de Namor, Angela F; Chaaban, Jinane K; Piro, Oscar E; Castellano, Eduardo E


    Standard solution Gibbs energies, DeltasG degrees, of the resorcarene-based receptor 5,11,17,23-ethylthiomethylated calix[4]resorcarene, (characterized by 1H NMR and X-ray diffraction studies) in its monomeric state (established through partition experiments) in various solvents are for the first time reported in the area of resorcarene chemistry. Transfer Gibbs energies of from hexane (reference solvent) to other medium are calculated. Agreement between DeltatG degrees (referred to the pure solvents) and standard partition Gibbs energies, DeltapG degrees (solvent mutually saturated) is found. Cation-ligand interactions were investigated through 1H NMR (CD3CN and CD3OD) and conductometric titrations in acetonitrile and methanol. 1H NMR data revealed the sites of interaction of with the metal cation. The composition of the metal-ion complexes (Ag+ and Pb2+ in acetonitrile and Ag+ and Cu2+ in methanol) was established through conductometric titrations. Thus, complexes of 1:1 stoichiometry were formed between and Ag+ and Pb2+ in acetonitrile and Cu2+ in methanol. However, in moving from acetonitrile to methanol, the composition of the silver complex was altered. Thus, two metal cations are hosted by a unit of the ligand. As far as Cu2+ and in acetonitrile is concerned, conductance data suggest that metalates are formed in which up to four units of Cu2+ are taken up per unit of resorcarene. The contrasting behavior of with Cu2+ in acetonitrile relative to methanol is discussed. As far as mercury (II) is concerned, the unusual jump in conductance observed in the titration of Hg2+ with in acetonitrile and methanol after the formation of a multicharged complex (undefined composition) is attributed to the presence of highly charged smaller units (higher mobility) resulting from the departure of pendant arms from the resorcarene backbone. Isolation of these species followed by X-ray diffraction studies corroborated this statement. The thermodynamic characterization of metal

  17. Detailed analytical study of radiolysis products of simple organic compounds as a methodological approach to investigate prebiotic chemistry-Part 1

    Energy Technology Data Exchange (ETDEWEB)

    Dondi, D., E-mail: dondi@unipv.i [Department of General Chemistry, University of Pavia, Via Taramelli 12, Pavia 27100 (Italy); Merli, D. [Department of General Chemistry, University of Pavia, Via Taramelli 12, Pavia 27100 (Italy); Pretali, L. [Department of Organic Chemistry, University of Pavia, Via Taramelli 10, Pavia 27100 (Italy); Buttafava, A.; Faucitano, A. [Department of General Chemistry, University of Pavia, Via Taramelli 12, Pavia 27100 (Italy)


    Aqueous solutions of simple organic C1 compounds (methanol and acetonitrile) and ammonia, presumably present on primordial Earth, were subjected to {sup 60}Co gamma irradiation (total dose 800 kGy). The irradiation gave a complex mixture of organic compounds leading interestingly to a positive balance of synthesis vs. degradation reactions. In particular, if acetonitrile was used, nucleobase analogues could be detected among products. Highly sensitive and powerful analytical techniques (e.g. GC-MS, HPLC-MS) made this investigation feasible at a reasonable cost in terms of time and results. Plausible reaction pathways leading to major compounds were proposed, supported by literature data.

  18. Formation of Oxazoles from Elusive Gold(I) α-Oxocarbenes: A Mechanistic Study. (United States)

    Schulz, Jiří; Jašík, Juraj; Gray, Andrew; Roithová, Jana


    The gold(I) catalyzed reaction between phenylacetylene, pyridine N-oxide and acetonitrile leading, via a putative gold-α-oxocarbene intermediate, towards an oxazole product has been investigated. A novel mass spectrometric method called "delayed reactant labeling" is used to track consecutive and parallel reactions. It clearly shows that the intramolecular formation of a pyridine adduct of gold-α-oxocarbene is in competition with the formation of the oxazole product. The reaction mechanism most probably corresponds to competition between acetonitrile and pyridine in an almost barrierless reaction with putative gold-α-oxocarbene within the solvent cage. The detected ionic species have been characterized by helium tagging infrared photodissociation spectroscopy.

  19. Laser Flash Photolysis Studies on Gallic Acid

    Institute of Scientific and Technical Information of China (English)

    ZHU Hong-Ping; ZHAO Hong-Wei; ZHANG Zhao-Xia; WANG Wen-Feng; YAO Si-De


    The transient species of gallic acid (GA) have been studied by 266 nm nanosecond laser flash photolysis in aqueous solution and acetonitrile. The intermediate with absorption at 320 nm was identified as excited triplet state (3GA*), the decay rates of which were obtained in aqueous solution and acetonitrile respectively. Energy transfer from 3GA* to β-carotene was observed and the energy transfer rate constant kent was determined to be 2.2 × 109 mol-1·L·s-1. GA underwent photoionization during photolysis and the quantum yield of photoionization was determined to be 0.12 at room temperature with KI as a reference.

  20. Rapid and simultaneous determination of imidazolium and pyridinium ionic liquid cations by ion-pair chromatography using a monolithic column

    Institute of Scientific and Technical Information of China (English)

    Xu Huang; Hong Yu; Ying Jie Dong


    A method for rapid and simultaneous determination of imidazolium and pyridinium ionic liquid cations by ion-pair chromatography with ultraviolet detection was developed.Chromatographic separations were performed on a reversed-phase silica-based monolithic column using 1-heptanesulfonic acid sodium-acetonitrile as mobile phase.The effects of ion-pair reagent and acetonitrile concentration on retention of the cations were investigated.The retention times of the cations accord with carbon number rule.The method has been successfully applied to the determination of four ionic liquids synthesized by organic chemistry laboratory.

  1. Synthesis and characterization of an iron complex bearing a cyclic tetra-N-heterocyclic carbene ligand: An artifical heme analogue?

    KAUST Repository

    Anneser, Markus R.


    An iron(II) complex with a cyclic tetradentate ligand containing four N-heterocyclic carbenes was synthesized and characterized by means of NMR and IR spectroscopies, as well as by single-crystal X-ray structure analysis. The iron center exhibits an octahedral coordination geometry with two acetonitrile ligands in axial positions, showing structural analogies with porphyrine-ligated iron complexes. The acetonitrile ligands can readily be substituted by other ligands, for instance, dimethyl sulfoxide, carbon monoxide, and nitric oxide. Cyclic voltammetry was used to examine the electronic properties of the synthesized compounds. © 2015 American Chemical Society.

  2. HPLC-UV determination of metformin in human plasma for application in pharmacokinetics and bioequivalence studies. (United States)

    Porta, Valentina; Schramm, Simone Grigoleto; Kano, Eunice Kazue; Koono, Eunice Emiko; Armando, Yara Popst; Fukuda, Kazuo; Serra, Cristina Helena Dos Reis


    In this study, a simple, rapid and sensitive HPLC method with UV detection is described for determination of metformin in plasma samples from bioequivalence assays. Sample preparation was accomplished through protein precipitation with acetonitrile and chromatographic separation was performed on a reversed-phase phenyl column at 40 degrees C. Mobile phase consisted of a mixture of phosphate buffer and acetonitrile at flow rate of 1.0 ml/min. Wavelength was set at 236 nm. The method was applied to a bioequivalence study of two drug products containing metformin, and allowed determination of metformin at low concentrations with a higher throughput than previously described methods.

  3. Determining water content in activated carbon for double-layer capacitor electrodes (United States)

    Egashira, Minato; Izumi, Takuma; Yoshimoto, Nobuko; Morita, Masayuki


    Karl-Fisher titration is used to estimate water contents in activated carbon and the distribution of impurity-level water in an activated carbon-solvent system. Normalization of the water content of activated carbon is attempted using vacuum drying after immersion in water was controlled. Although vacuum drying at 473 K and 24 h can remove large amounts of water, a substantial amount of water remains in the activated carbon. The water release to propylene carbonate is less than that to acetonitrile. The degradation of capacitor cell capacitance for activated carbon with some amount of water differs according to the electrolyte solvent type: acetonitrile promotes greater degradation than propylene carbonate does.

  4. Room-temperature phosphonium ionic liquids for supercapacitor application (United States)

    Frackowiak, Elzbieta; Lota, Grzegorz; Pernak, Juliusz


    Ionic liquids (ILs) have been used as electrolytes for supercapacitors. Two phosphonium salts such as trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide (IL1) and trihexyl(tetradecyl) phosphonium dicyanamide (IL2) have been selected for this target. To decrease the viscosity of ILs, a small amount of acetonitrile (from 5 to 25 wt %) was added. Supercapacitor based on activated carbon (AC) as electrodes and IL1 with 25 wt % of acetonitrile supplied capacitance values of 100F/g at a high operating voltage of 3.4 V. Such a supercapacitor reached a high energy of ˜40Wh/kg and a good cyclability.

  5. Electrochemical reduction of carbon fluorine bond in 4-fluorobenzonitrile Mechanistic analysis employing Marcus Hush quadratic activation-driving force relation (United States)

    Muthukrishnan, A.; Sangaranarayanan, M. V.


    The reduction of carbon-fluorine bond in 4-fluorobenzonitrile in acetonitrile as the solvent, is analyzed using convolution potential sweep voltammetry and the dependence of the transfer coefficient on potential is investigated within the framework of Marcus-Hush quadratic activation-driving force theory. The validity of stepwise mechanism is inferred from solvent reorganization energy estimates as well as bond length calculations using B3LYP/6-31g(d) method. A novel method of estimating the standard reduction potential of the 4-fluorobenzonitrile in acetonitrile is proposed.

  6. The electrochemical oxidation of dimethyl disulfide-Anodic methylsulfanylation of phenols and aromatic ethers

    Energy Technology Data Exchange (ETDEWEB)

    Quang Tho Do [Laboratoire d' Electrochimie et Environnement, CEREA, Universite Catholique de l' Ouest, BP 10808, 49008 ANGERS Cedex 01 (France); Elothmani, Driss [Laboratoire GRAPPE, Ecole Superieure d' Agriculture d' Angers, BP 30748, 49007 ANGERS Cedex 01 (France); Simonet, Jacques [Laboratoire d' Electrochimie Moleculaire (UMR CNRS 6510), Universite de RENNES 1, 35042 RENNES Cedex (France); Guillanton, Georges Le [Laboratoire d' Electrochimie et Environnement, CEREA, Universite Catholique de l' Ouest, BP 10808, 49008 ANGERS Cedex 01 (France)]. E-mail:


    The electrochemical oxidation of dimethyl disulfide was investigated in acetonitrile and dichloromethane. The nature of the oxidation strongly depends on the nucleophilicity of the solvent. In acetonitrile a one-electron oxidation is observed and the consecutive species did not exhibit any reactivity towards aromatic compounds subject to electrophile substitution. On the contrary, the oxidation of dimethyl disulfide in methylene chloride afforded a two-electron process with the formation of a species consistent with CH{sub 3} -S{sup +}. Its reactivity towards phenols and aromatic ethers was confirmed and showed a selective monomethylsulfanylation in most of the cases.

  7. Comparison of concentration pulse and tracer pulse chromatography: experimental determination of eluent uptake by bridged-ethylene hybrid ultra high performance liquid chromatography packings (United States)

    Excess volume isotherms of acetonitrile and methanol sorbed on a C18 BEH UHPLC packing were determined over a range of pressure, temperature, flow rate and eluent composition. The isotherm measurements were carried out by two independent experimental methods, viz., concentration pulse and tracer pul...

  8. Reversible Tailoring of Mechanical Properties of Carbon Nanotube Forests by Immersing in Solvents (United States)


    in Fig. 9c,d respectively. Maxi - mum harmonic stiffness for these three tests on a short CNT forest using acetonitrile, a tall CNT forest relatively weak in the transverse direction and, therefore, have lower stiffness in this direction. To investigate the signif- icance of this effect

  9. A Novel Catalytic Method for the Oxidation of Sulfides to Sulfoxides with Silica Sulfuric Acid and Sodium Nitrite in the Presence of KBr and/or NaBr as Catalyst

    Institute of Scientific and Technical Information of China (English)



    Highly efficient selective oxidation of sulfides to sulfoxides by NaNO2 and silica sulfuric acid catalyzed with KBr or NaBr has been reported.This oxidation was carried out in the presence of wet SiO2(50% w/w)in acetonitrile at room temperature with good to excellent yields.

  10. Synthesis and electrochemistry of 6 nm ferrocenated indium-tin oxide nanoparticles. (United States)

    Roberts, Joseph J P; Vuong, Kim T; Murray, Royce W


    Indium-tin oxide (ITO) nanoparticles, 6.1 ± 0.8 nm in diameter, were synthesized using a hot injection method. After reaction with 3-aminopropyldimethylethoxysilane to replace the initial oleylamine and oleic acid capping ligands, the aminated nanoparticles were rendered electroactive by functionalization with ferrocenoyl chloride. The nanoparticle color changed from blue-green to light brown, and the nanoparticles became more soluble in polar solvents, notably acetonitrile. The nanoparticle diffusion coefficient (D = 1.0 × 10(-6) cm(2)/s) and effective ferrocene concentration (C = 0.60 mM) in acetonitrile solutions were determined using ratios of DC and D(1/2)C data measured by microdisk voltammetry and chronoamperometry. The D result compares favorably to an Einstein-Stokes estimate (2.1 × 10(-6) cm(2)/s), assuming an 8 nm hydrodynamic diameter in acetonitrile (6 nm for the ITO core plus 2 nm for the ligand shell). The ferrocene concentration result is lower than anticipated (ca. 1.60 mM) based on a potentiometric titration of the ferrocene sites with Cu(II) in acetonitrile. Cyclic voltammetric data indicate tendency of the ferrocenated nanoparticles to adsorb on the Pt working electrode.

  11. Explicit solvent DRF INDOs/CIS computations of charge transfer state energetics in a pyrenyldeoxyuridine nucleoside model

    NARCIS (Netherlands)

    Van Duijnen, PT; Netzel, TL


    In this work we present calculated absorption and emission spectra in acetonitrile (MeCN) solution of N-acetyl-1-aminopyrene (PAAc, a spectroscopic model compound) and N-(1-pyrenyl)-1-methyluracil-5-carboxamide (PAU(Me), a computational model for 5-(N-carboxyl-1-aminopyrenyl)-2'-deoxyuridine (PAdU))

  12. Room-Temperature Ionic Liquids for Electrochemical Capacitors (United States)

    Fireman, Heather; Yowell, Leonard; Moloney, Padraig G.; Arepalli, Sivaram; Nikolaev, P.; Huffman, C.; Ready, Jud; Higgins, C.D.; Turano, S. P.; Kohl, P.A.; Kim, K.


    A document discusses room-temperature ionic liquids (RTILs) used as electrolytes in carbon-nanotube-based, electrochemical, double-layer capacitors. Unlike the previous electrolyte (EtNB4 in acetonitrile), the RTIL used here does not produce cyanide upon thermal decomposition and does not have a moisture sensitivity.

  13. New analogues of epiboxidine incorporating the 4,5-dihydroisoxazole nucleus

    DEFF Research Database (Denmark)

    Dallanoce, Clelia; Magrone, Pietro; Bazza, Paola;


    A group of novel 4,5-dihydro-3-methylisoxazolyl derivatives, structurally related to epiboxidine (=(1R,4S,6S)-6-(3-methylisoxazol-5-yl)-7-azabicyclo[2.2.1]heptane), was prepared via 1,3-dipolar cycloaddition of acetonitrile oxide to different olefins. Target compounds 1a and 1b, 2a and 2b, 3, 4, ...

  14. Isonitrile iron(II) complexes with chiral N2P2 macrocycles in the enantioselective transfer hydrogenation of ketones. (United States)

    Bigler, Raphael; Mezzetti, Antonio


    Bis(isonitrile) iron(II) complexes bearing a C2-symmetric N2P2 macrocyclic ligand, which are easily prepared from the corresponding bis(acetonitrile) analogue, catalyze the asymmetric transfer hydrogenation (ATH) of a broad scope of ketones in excellent yields (up to 98%) and with high enantioselectivity (up to 91% ee).

  15. Crown ether activation of cross-linked subtilisin Carlsberg crystals in organic solvents

    NARCIS (Netherlands)

    Unen, van Dirk-Jan; Sakodinskaya, Inna K.; Engbersen, Johan F.J.; Reinhoudt, David N.


    The activity of cross-linked subtilisin Carlsberg crystals in the catalysis of peptide bond formation can be significantly enhanced by pretreatment of the enzyme crystals with crown ethers. Soaking of the enzyme crystals in a solution of crown ether in acetonitrile followed by evaporation of the sol

  16. Cycloadditions in mixed aqueous solvents : the role of the water concentration

    NARCIS (Netherlands)

    Rispens, T; Engberts, JBFN


    We examined the kinetics of a series of cycloaddition reactions in mixtures of water with methanol, acetonitrile and poly(ethylene glycol) (MW 1000). The reactions include the Diels-Alder (DA) reaction between cyclopentadiene and N-n-butylmaleimide or acridizinium bromide, the retro-Diels-Alder (RDA

  17. Structural dynamics in water probed by heterodyne-detected photon echo

    NARCIS (Netherlands)

    Yeremenko, S; Pshenichnikov, MS; Wiersma, DA; Miller, DR; Murnane, MM; Scherer, NF; Weiner, AM


    Results of heterodyne-detected photon echo experiments on the OH stretching mode of HDO molecule in heavy water and acetonitrile are reported and discussed. Two vibrational dynamical processes with time constants of 130 A and 900 fs were identified. The former is attributed to bond breaking dynamics

  18. Enthalpy of mixing of methacrylic acid with organic solvents at 293 K (United States)

    Sergeev, V. V.


    The enthalpies of mixing of binary systems of methacrylic acid with acetonitrile, benzene, hexane, 1,2-dichloroethane, and acetic acid are measured calorimetrically at 293 K and atmospheric pressure. The enthalpy of mixing of all the studied binary systems is positive over the range of concentrations.


    A Sn-doped hydrotalcite (Sn/HT) catalyst prepared by ion-exchange is found to be an active and selective catalyst for the liquid phase Baeyer-Villiger (BV) oxidation of cyclic ketones in acetonitrile using hydrogen peroxide (H2O2) as oxidant. Different reaction perameters such as...

  20. Ferric Perchlorate Catalyzed One-pot Synthesis of 1,2,3,4-Tetrahydro-2-pyrimidinones and -thiones:an Expedient Protocol for the Biginelli Reaction

    Institute of Scientific and Technical Information of China (English)

    HERAVI,Majid Momahed; BEHBAHANI,Farahnaz Kargar OSKOOIE; Hossien Abdi


    An efficient synthesis of 1,2,3,4-tetrahydro-2-pyrimidinones and -thiones using ferric perchlorate as the catalyst from an aldehyde, ethyl acetoacetate, and urea or thiourea in acetonitrile was described. Compared to the classical Biginelli reaction conditions, this new method consistently has the advantage of full catalysis, good yields and short reaction time.


    NARCIS (Netherlands)



    Reactions of (NPCl2)3 with NaNCO in the presence of aliphatic alcohols have been investigated. Using an equimolar amount of NaNCO in refluxing acetonitrile, high yields of mono(urethane) derivatives N3P3Cl5(NHCO2R) were obtained. Disubstitution is mainly non-geminal. Reactions of (NPCl2)3 with AgNCO

  2. Influence of microwave heating on liquid-liquid phase inversion and temperature rates for immiscible mixtures. (United States)

    Kennedy, Alvin; Tadesse, Solomon; Nunes, Janine; Reznik, Aron


    Time dependencies of component temperatures for mixtures of immiscible liquids during microwave heating were studied for acetonitrile-cyclohexane and water-toluene. For the first time, we report microwave induced liquid-liquid phase inversion for acetonitrile-cyclohexane mixture: acetonitrile layer was initially at the bottom of the mixture, after 10 sec of microwave heating its density decreased and it inverted to the top of the mixture for the remainder of the microwave heating. This phase inversion could not be achieved by conventional radiant heating. The maximum rate of temperature growth for the polar component of the mixtures was 2 - 5 times larger than for the non-polar component. This suggests that microwave energy is absorbed by polar liquids (water or acetonitrile) and heat is transferred into the non-polar liquid (toluene or cyclohexane) in the mixture by conduction (in case of cyclohexane) or conduction and convection (in case of toluene). Comparison between experimental data and semi-empirical mathematical models, proposed in [Kennedy et at., 2009] showed good correlation. Average relative error between theoretical and experimental results did not exceed 7%. These results can be used to model the temperature kinetics of components for other multiphase mixtures.

  3. Zn(NO_3)_2·6H_2O/2,4,6-trichloro-1,3,5-triazine(TCT) a mild and selective system for nitration of phenols

    Institute of Scientific and Technical Information of China (English)

    Firouzeh; Nemati; Hossein; Kiani


    Certain phenols and naphthols were nitrated regioselectively with Zn(NO_3)_2·6H_2O/TCT in acetonitrile as solvent at room temperature and short reaction time in good yields.The reaction condition was mild.TCT is a cheap and commercially available reagent.It performed as an acid catalyst in this transformation.

  4. Electrochemical properties of pyridine and dihydropyridine derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Abou-Elenien, G.; Rieser, J.; Ismail, N.; Wallenfels, K.


    The electrochemical oxidation and reduction properties of different dihydropyridines and pyridines have been investigated in non aqueous solvent as benzonitrile and acetonitrile with tetra-n-butylammonium perchlorate as supporting electrolyte at platinum electrodes using DC-voltametry, cycl. voltametry and coulometry. Possible redox-mechanisms are discussed.

  5. Iron-Promoted Practical One-Pot Synthesis of 2,5-Disubstituted Oxazoles

    Institute of Scientific and Technical Information of China (English)

    陈松辉; 白东虎; 时锋; 李健; 李春举; 贾学顺


    A practical one-pot protocol for the synthesis of 2,5-disubstituted oxazoles from 1-aryl-2-nitroethanones was reported. In the presence of iron/AcOH in acetonitrile, the reaction of 1-aryl-2-nitroethanones with trimethyl orthoacetate or trimethyl orthobenzoate delivered the corresponding 2,5-disubstituted oxazoles in moderate to good yields.

  6. A Novel Organic-Inorganic Complex: Synthesis and Crystal Structure of [Ca(DMSO)5(H2O)]2SiMo12O40

    Institute of Scientific and Technical Information of China (English)


    A novel organic-inorganic complex [Ca(DMSO)5(H2O)]2SiMo12O40 was synthesized from CaCl2, DMSO and H4SiMo12O40(nH2O in mixed solvent of acetonitrile and water. Its structure was characterized with elemental analysis, IR and X-ray diffraction analysis.

  7. SBA-15-Pr-SO3H: An efficient, environment friendly and recyclable heterogeneous nanoreactor catalyst for the one-pot multicomponent synthesis of -acetamido ketones

    Indian Academy of Sciences (India)

    Kiumars Bahrami; Mohammad M Khodaei; Peyman Fattahpour


    SBA-15-Pr-SO3H catalyzes the multi-component condensation of aromatic aldehydes, ketones and acetonitrile in the presence of acetyl chloride at 80°C to afford -acetamido ketones in excellent yields. The catalyst can be recovered and recycled for subsequent reactions without any appreciable loss of efficiency.

  8. [Multi-residue method for determination of veterinary drugs and feed additives in meats by HPLC]. (United States)

    Chonan, Takao; Fujimoto, Toru; Ueno, Ken-Ichi; Tazawa, Teijiro; Ogawa, Hiroshi


    A simple and rapid multi-residue method was developed for the determination of 28 kinds of veterinary drugs and feed additives (drugs) in muscle of cattle, pig and chicken. The drugs were extracted with acetonitrile-water (95:5) in a homogenizer and ultrasonic generator. The extracted solution was poured into an alumina column and the drugs were eluted with acetonitrile-water (90:10). The eluate was washed with n-hexane saturated with acetonitrile and then evaporated. The drugs were separated on a Inertsil ODS-3V column (4.6 mm i.d. x 250 mm) with a gradient system of 0.1% phosphoric acid-acetonitrile as the mobile phase, with monitoring at 280 and 340 nm. The recoveries of the 26 kinds of drugs were over 60% from the meats fortified at 0.1 microg/g, and the quantification limits of most drugs were 0.01 microg/g. This proposed method was found to be effective and suitable for the screening of the above drugs in meats.

  9. Liquid chromatographic method for nicarbazin in broiler feeds and premixtures: development, validation and interlaboratory study

    NARCIS (Netherlands)

    Jong, de J.; Tomassen, M.J.H.; Driessen, J.J.M.; Putzka, H.A.; Brambilla, G.


    A reversed-phase liquid chromatography method for nicarbazin in broiler feeds and premixtures was developed, validated, and interlaboratory studied. The extraction solvent was an acetonitrile-methanol (1 + 1) mixture. For feedingstuffs, water was also added. The 4,4'-dinitrocarbanilide moiety of nic

  10. An autocatalytic radical chain pathway in formation of an iron(IV)-oxo complex by oxidation of an iron(II) complex with dioxygen and isopropanol. (United States)

    Morimoto, Yuma; Lee, Yong-Min; Nam, Wonwoo; Fukuzumi, Shunichi


    Evidence of an autocatalytic radical chain pathway has been reported in formation of a non-heme iron(IV)-oxo complex by oxidation of an iron(II) complex with dioxygen and isopropanol in acetonitrile at 298 K. The radical chain reaction is initiated by hydrogen abstraction from isopropanol by the iron(IV)-oxo complex.

  11. Oxygenated compounds in aged biomass burning plumes over the Eastern Mediterranean: evidence for strong secondary production of methanol and acetone

    Directory of Open Access Journals (Sweden)

    R. Holzinger


    Full Text Available Airborne measurements of acetone, methanol, PAN, acetonitrile (by Proton Transfer Reaction Mass Spectrometry, and CO (by Tunable Diode Laser Absorption Spectroscopy have been performed during the Mediterranean Intensive Oxidants Study (MINOS, August 2001. In the course of the campaign 10 biomass burning plumes, identified by strongly elevated acetonitrile mixing ratios, were found. The characteristic biomass burning signatures obtained from these plumes reveal secondary production of acetone and methanol, while CO photochemically declines in the plumes. Mean excess mixing ratios – normalized to CO – of 1.8%, 0.20%, 3.8%, and 0.65% for acetone, acetonitrile, methanol, and PAN, respectively, were found in the plumes. By scaling to an assumed global annual source of 663–807 Tg CO, biomass burning emissions of 25–31 and 29–35 Tg/yr for acetone and methanol are estimated, respectively. Our measurements suggest that the present biomass burning contributions of acetone and methanol are significantly underestimated due to the neglect of secondary formation. Median acetonitrile mixing ratios throughout the troposphere were around 150 pmol/mol; this is in accord with current biomass burning inventories and an atmospheric lifetime of ~6 months.

  12. Protection of Hydroxyl Groups as a Trimethylsilyl Ether by1,1,1,3,3,3-Hexamethyldisilazane Promoted by Aspartic Acid as an Efficient Organocatalyst%Protection of Hydroxyl Groups as a Trimethylsilyl Ether by 1,1,1,3,3,3-Hexamethyldisilazane Promoted by Aspartic Acid as an Efficient Organocatalyst

    Institute of Scientific and Technical Information of China (English)



    A wide variety of alcohols and phenols were protected as trimethylsilyl ethers using 1,1,1,3,3,3-hexamethyl disilazane catalyzed by aspartic acid as a non-toxic, metal-free, and green organocatalyst at room temperature in acetonitrile under mild and heterogeneous conditions. The procedure is operationally simple and the silylated product was obtained in high yield and purity.

  13. Prediction of Molar Extinction Coefficients of Proteins and Peptides Using UV Absorption of the Constituent Amino Acids at 214 nm To Enable Quantitative Reverse Phase High-Performance Liquid Chromatography-Mass Spectrometry Analysis

    NARCIS (Netherlands)

    Kuipers, B.J.H.; Gruppen, H.


    The molar extinction coefficients of 20 amino acids and the peptide bond were measured at 214 nm in the presence of acetonitrile and formic acid to enable quantitative comparison of peptides eluting from reversed-phase high-performance liquid chromatography, once identified with mass spectrometry (R

  14. A fast and simple method for quantitative determination of fat-derived medium and low-volatile compounds in cheese

    NARCIS (Netherlands)

    Alewijn, M.; Sliwinski, E.L.; Wouters, J.T.M.


    Cheese flavour is a mixture of many (volatile) compounds, mostly formed during ripening. The current method was developed to qualify and quantify fat-derived compounds in cheese. Cheese samples were extracted with acetonitrile, which led to a concentrated solution of potential favour compounds, main

  15. Synthesis and reactivity of trigonal copper(I) compounds, crystal structure of bis(tetrahydropyrimidine-2-thione)copper(I) bromide

    NARCIS (Netherlands)

    Akrivos, PD; Karagiannidis, P; Herrema, J; Luic, M; KojicProdic, B


    Reaction of monovalent copper halides with excess tetrahydropyrimidine-2-thione (thpmtH(2)) in acetonitrile results in the formation of three-coordinate monomer products of formula Cu(thpmtH(2))(2)X. The crystal and molecular structure of the bromo complex is reported and discussed with respect to a


    An efficient ultrasound-assisted epoxidation of olefins and a,B-unsaturated ketones over hydrotacite catalysts in the presence of hydrogen peroxide and acetonitrile is described. This general and selective protocol is relatively fast and is applicable to a wide variety of substra...

  17. 4-Hydroxy-1-naphthaldehydes: proton transfer or deprotonation

    DEFF Research Database (Denmark)

    Manolova, Y; Kurteva, V; Antonov, L


    . For 4-hydroxy-3-(piperidin-1-ylmethyl)-1-naphthaldehyde (a Mannich base) an intramolecular proton transfer involving the OH group and the piperidine nitrogen occurs. In acetonitrile the equilibrium is predominantly at the OH-form, whereas in methanol the proton transferred tautomer is the preferred form...

  18. The Construction and Behaviour of Ultramicroelectrodes: Investigations of Novel Electrochemical Systems. (United States)


    equivalent circuit is simplified. Fig is an illustration of the cyclic voltametry of the ferricyanide/ferrocyanide couple at a thin ring electrode of...5.d radius in solid acetonitrile. Fit. 9 Cyclic voltammogram of 10 mM potassium ferrocyanide In o.1K 10H at the gold ring electrode; sep rate 100 mV


    NARCIS (Netherlands)



    Liquid chromatography-ionspray mass spectrometry was used to elucidate the structures of the decomposition products of salbutamol. The best sensitivity in mass spectrometry was achieved by using a mixture of acetonitrile and ammonium formate (10 mM, pH 3.3) as the mobile phase in liquid chromatograp

  20. CrCl3·6H2O/Hydrogenated Bis-Schiff Base as a New Efficient Catalyst System for Synthesis of Bis(indoly) Methane%CrCl3·6H2O/Hydrogenated Bis-Schiff Base as a New Efficient Catalyst System for Synthesis of Bis(indoly) Methane

    Institute of Scientific and Technical Information of China (English)

    杨永磊; 解正峰; 王吉德


    CrCl3·6H2O/hydrogenated bis-Schiff base is found to be an effective catalyst system for synthesis of bis(indoly) methane via electrophilic addition reaction of indoles with aldehydes using acetonitrile as the solvent. The yields of isolated products are from good to excellent.

  1. 2-(1 H-Benzotriazole-1-yl)-1,1,3,3-Tetramethyluronium Tetrafluoro Borate (TBTU) as an Efficient Coupling Reagent for the Esterification of Carboxylic acids with Alcohols and Phenols at Room Temperature

    Institute of Scientific and Technical Information of China (English)



    Esterification of carboxylic acids with alcohols and phenols by using 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate (TBTU) in the presence of triethylamine as a base proceeded smoothly under mild conditions to afford the corresponding esters in good to high yields in acetonitrile at room temperature.

  2. Cu catalyzed oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran and 2,5-furandicarboxylic acid under benign reaction conditions

    DEFF Research Database (Denmark)

    Hansen, Thomas S.; Sádaba, Irantzu; Garcia, Eduardo;


    containing promoters (NCPs) to obtain excellent yields. In acetonitrile a 95% DFF yield was obtained after 24h with ambient pressure of dioxygen at room temperature in the presence of different NCPs, which – to our knowledge – is the best result reported thus far for this reaction. The use of NCPs made...

  3. Photophysics of trioxatriangulenium ion. Electrophilic reactivity in the ground state and excited singlet state

    DEFF Research Database (Denmark)

    Reynisson, J.; Wilbrandt, R.; Brinck, V.


    of the long wavelength absorption band. A strong fluorescence is observed at 520 nm (tau(n) = 14.6 ns, phi(n) = 0.12 in deaerated acetonitrile). The fluorescence is quenched by 10 aromatic electron donors predominantly via a dynamic charge transfer mechanism, but ground state complexation is shown...

  4. Excited state proton transfer in the Cinchona alkaloid cupreidine

    NARCIS (Netherlands)

    J. Qian; A.M. Brouwer


    Photophysical properties of the organocatalyst cupreidine (CPD) and its chromophoric building block 6-hydroxyquinoline (6HQ) in protic and nonprotic polar solvents (methanol and acetonitrile) were investigated by means of UV-vis absorption, and steady state and time resolved fluorescence spectroscop

  5. Using a Combination of Experimental and Mathematical Method to Explore Critical Micelle Concentration of a Cationic Surfactant (United States)

    Goronja, Jelena; Pejic´, Natas?a; Lez?aic´, Aleksandra Janos?evic´; Stanisavljev, Dragomir; Malenovic, Andelija


    An undergraduate electrical conductivity measurement experiment in a physical chemistry lab and basic fitting procedures are presented that allow a characterization of micellar system of hexadecyltrimethylammonium bromide (cetyltrimethylammonium bromide, CTAB) in binary mixture of water and acetonitrile (ACN) as a cosolvent (10%, v/v) at 30.0 °C.…

  6. Rapid screening of oxytetracycline residue in catfish muscle by dispersive liquid-liquid microextraction and europium-sensitized luminescence (United States)

    Oxytetracycline (OTC) residue in catfish muscle was screened by dispersive liquid-liquid microextraction (DLLME) and europium-sensitized luminescence (ESL). After extraction in EDTA, HCl, and acetonitrile, cleanup was carried out by DLLME, and ESL was measured at microgram = 385 nm and wavelength = ...

  7. Luminescence screening of enrofloxacin and ciprofloxacin residues in swine liver after dispersive liquid - liquid microextraction cleanup (United States)

    A rapid luminescence method was developed to screen residues of enrofloxacin (ENRO) and its metabolite, ciprofloxacin (CIPRO), in swine liver. Target analytes were extracted in acetonitrile-2.5% trifluoroacetic acid-NaCl, cleaned up by dispersive liquid-liquid microextraction (DLLME), and finally de...

  8. The Synthesis of Novel 3-Substituted Poly(pyrroles) Bearing Crown-ether Moieties and a Study of their Electrochemical Properties

    DEFF Research Database (Denmark)

    Guernion, Nicolas J.L.; Blencowe, A.; Hayes, Wayne;


    A series of fourteen novel pyrrole monomers substituted at the 3-position with aliphatic and aromatic crown-ether moieties have been synthesised in good yield and characterised extensively. Several of those compounds were electropolymerised successfully in acetonitrile, using both potentiostatic ...

  9. Morita–Baylis–Hillman reaction of acrylamide with isatin derivatives

    Directory of Open Access Journals (Sweden)

    Radhey M. Singh


    Full Text Available The Morita–Baylis–Hillman reaction of acrylamide, as an activated alkene, has seen little development due to its low reactivity. We have developed the reaction using isatin derivatives with acrylamide, DABCO as a promoter and phenol as an additive in acetonitrile. The corresponding aza version with acrylate and acrylonitrile has also been developed resulting in high product yields.

  10. Formation of Diffusion Layers by Anode Plasma Electrolytic Nitrocarburizing of Low-Carbon Steel (United States)

    Kusmanov, S. A.; Kusmanova, Yu. V.; Naumov, A. R.; Belkin, P. N.


    The structure of the low-carbon steel after plasma electrolytic nitrocarburizing in the electrolyte containing acetonitrile was investigated. The cross-sectional microstructure, composition, and phase constituents of a modified layer under different processing conditions were characterized. It is shown that the electrolyte that contained ammonium chloride and acetonitrile provides the saturation of steel with nitrogen and carbon and the formation of the Fe4N and FeN0.05 nitrides, Fe4C carbide and other phases. The nitrogen diffusion decreases the austenitization temperature and results in the formation of martensite after the sample cooling in the electrolyte. The formation of a carbon and nitrogen source in a vapor-gas envelope (VGE) is investigated. The proposed mechanism includes evaporation of acetonitrile in the VGE, its adsorption on an anode with the following thermal decomposition, and also the acetonitrile reduction to amine with subsequent hydrolysis to ethanol that is determined with the use of chromatographic method. The aqueous solution that contained 10 wt.% NH4Cl and 10 wt.% CH3CN allows one to obtain the nitrocarburized layer with the thickness of 0.22 mm and microhardness up to 740 HV during 10 min at 850 °C. This treatment regime leads to the decrease in the surface roughness of steel R a from 1.01 μm to 0.17 μm.



    Jacobson, Kenneth A.; FURLANO, DAVID C.; KIRK, KENNETH L.


    Fluoride ion as the tetrabutylammonium salt displaces bromide in para-substituted benzyl bromides in acetonitrile or dimethylformamide. The p-bromomethyl benzoyl (BMB) group has been coupled to amino groups, including peptide amino groups, via its N-hydroxysuccinimide ester. In a subsequent step, the facile displacement of bromide by fluoride occurred under conditions compatible for use with 18F radiotracers.

  12. Regularities of the sorption of 1,2,3,4-tetrahydroquinoline derivatives under conditions of reversed phase HPLC (United States)

    Nekrasova, N. A.; Kurbatova, S. V.; Zemtsova, M. N.


    Regularities of the sorption of 1,2,3,4-tetrahydroquinoline derivatives on octadecylsilyl silica gel and porous graphitic carbon from aqueous acetonitrile solutions were investigated. The effect the molecular structure and physicochemical parameters of the sorbates have on their retention characteristics under conditions of reversed phase HPLC are analyzed.

  13. The micro-flow reaction system featured the liquid-liquid interface created with ternary mixed carrier solvents in a capillary tube. (United States)

    Masuhara, Yuji; Jinno, Naoya; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko


    A micro-flow reaction system was developed in which liquid-liquid interface was created based on the tube radial distribution of ternary mixed carrier solvents. The system was constructed from double capillary tubes having different inner diameters (100 and 250 µm i.d.). The smaller tube was inserted into the larger one through a T-type joint. The reaction of a protein with a fluorescence derivatizing reagent was adopted as a model. A water-acetonitrile mixture (3:1 volume ratio) including bovine serum albumin (hydrophilic) was delivered into the large tube from the inside through the small tube and an acetonitrile-ethyl acetate mixture (7:4 volume ratio) containing fluorescamine (hydrophobic) as a derivatizing reagent was delivered from the outside through the joint. Solutions were mixed through the double capillary tubes to promote ternary mixed carrier solvents (water-acetonitrile-ethyl acetate; 1:2:1 volume ratio). The liquid-liquid interface was created based on the tube radial distribution of ternary solvents in the larger tube. The derivatization reaction was performed in the larger, or reaction, tube in the micro-flow system. The fluorescence intensity of the fluorescamine-derivatized bovine serum albumin obtained by the system, which specifically included the kinetic liquid-liquid interface in the tube, was greater than that obtained through a batch reaction using a homogeneous solution of water-acetonitrile (1:2 volume ratio).

  14. Experimental interstellar organic chemistry - Preliminary findings (United States)

    Khare, B. N.; Sagan, C.


    Review of the results of some explicit experimental simulation of interstellar organic chemistry consisting in low-temperature high-vacuum UV irradiation of condensed simple gases known or suspected to be present in the interstellar medium. The results include the finding that acetonitrile may be present in the interstellar medium. The implication of this and other findings are discussed.

  15. Flash and Continuous Photolysis Studies of the Thionitrosyl Complex Cr(CH3CN)5(NS)2+ and the Nitric Oxide Analogs. Reactions of Nitrogen Monosulfide in Solution

    DEFF Research Database (Denmark)

    Dethlefsen, Johannes Wied; Hedegård, Erik; Rimmer, R. Dale


    Photolysis of the thionitrosyl complex Cr(CH3CN)5(NS)2+ (1) in acetonitrile solution leads to the dissociation of nitrogen monosulfide (NS).  In deaerated solution, this reaction is reversible, and flash photolysis studies demonstrate that NS reacts with Cr(CH3CN)62+ according to the rate law d[1...

  16. High chemiluminescence activity of an Fe(III)-TAML activator in aqueous-organic media and its use in the determination of organic peroxides. (United States)

    Demiyanova, Alexandra S; Sakharov, Ivan Yu


    High activity of Fe(III)-TAML, peroxidase mimic, upon the catalytic oxidation of luminol in aqueous-organic media (ethanol, isopropanol and acetonitrile) was determined. Using Fe(III)-TAML the sensitive chemiluminescence assays for the determination of benzoyl peroxide and tert-butyl hydroperoxide in the presence of organic solvents were performed.

  17. Phenylboronic acid catalysed synthesis of 1,5-benzodiazepines via cyclocondensation of -phenylenediamine and ketones

    Indian Academy of Sciences (India)

    Santosh V Goswami; Prashant B Thorat; Sudhakar R Bhusare


    Phenylboronic acid has been found to be an efficient catalyst for the synthesis of 1,5-benzodiazepine derivatives via cyclocondensation of -phenylenediamine and various ketones in good to excellent yields (82-91%) using acetonitrile as solvent at reflux condition. The remarkable advantages offered by this method are easy mild reaction condition, experimental work up and good to excellent yields of products.

  18. Impact of the nature and composition of the mobile phase on the mass transfer mechanism in chiral reversed phase liquid chromatography. Application to the minimization of the solvent cost in chiral separations. (United States)

    Gritti, Fabrice; Guiochon, Georges


    The mechanism of mass transfer was studied on a cellulose-based chiral stationary phase (CSP, Lux Cellulose-1) using aqueous mixtures of acetonitrile (50/50-90/10, v/v) or methanol (90/10 and 100/0, v/v) as the mobile phase. An experimental protocol validated in RPLC and HILIC chromatography and recently extended to chiral RPLC was applied. The five mass-transfer contributions (longitudinal diffusion, short-range and long-range eddy dispersion, solid-liquid mass transfer resistances due to finite intra-particle diffusivity and slow adsorption-desorption) to the reduced height equivalent to a theoretical plate (HETP) were measured. The experimental results show that the adsorption rate constants kads of trans-stilbene enantiomers onto the CSP are three times larger with acetonitrile than with methanol as the organic modifier. This is correlated to the decrease of enantioselectivity from 1.4 (in methanol) to only 1.1 (in acetonitrile). The amount of solvent needed to achieve a separation factor of exactly 2.0 was determined. This showed that analysis cost could be reduced seven times by selecting pure methanol as the eluent for a 5cm long column rather than an acetonitrile-water mixture for a longer (20-45cm) column.

  19. Characterization and screening of pyrrolizidine alkaloids and N-oxides from various parts of many botanicals and dietary supplements using liquid chromatography high resolution mass spectrometry (United States)

    The UHPLC-QToF-MS analysis of pyrrolizidine alkaloids from various parts of 37 botanicals and 7 dietary supplements was performed. A separation by LC was achieved using a reversed-phase column and a gradient of water/acetonitrile each containing formic acid as the mobile phase. MS-MS detection was u...

  20. Coupled electron and proton transfer processes in 4-dimethylamino-2-hydroxy-benzaldehyde. (United States)

    Zgierski, Marek Z; Fujiwara, Takashige; Lim, Edward C


    TDDFT calculations, picosecond transient absorption, and time-resolved fluorescence studies of 4-dimethylamino-2-hydroxy-benzaldehyde (DMAHBA) have been carried out to study the electron and proton transfer processes in polar (acetonitrile) and nonpolar (n-hexane) solvents. In n-hexane, the transient absorption (TA) as well as the fluorescence originate from the ππ* state of the keto form (with the carbonyl group in the benzaldehyde ring), which is produced by an intramolecular proton transfer from the initially excited ππ* state of the enol form (OH group in the ring). The decay rate of TA and fluorescence are essentially identical in n-hexane. In acetonitrile, on the other hand, the TA exhibits features that can be assigned to the highly polar twisted intramolecular charge transfer (TICT) states of enol forms, as evidenced by the similarity of the absorption to the TICT-state absorption spectra of the closely related 4-dimethylaminobenzaldehyde (DMABA). As expected, the decay rate of the TICT-state of DMAHBA is different from the fluorescence lifetime of the ππ* state of the keto form. The occurrence of the proton and electron transfers in acetonitrile is in good agreement with the predictions of the TDDFT calculations. The very short-lived (∼1 ps) fluorescence from the ππ* state of the enol form has been observed at about 380 nm in n-hexane and at about 400 nm in acetonitrile.

  1. Synthesis and application of epoxy starch derivatives

    NARCIS (Netherlands)

    Huijbrechts, A.M.L.; Haar, ter R.; Schols, H.A.; Franssen, M.C.R.; Boeriu, C.G.; Sudhölter, E.J.R.


    Epoxy starch derivatives were synthesized by epoxidation of allylated starch. The reaction was performed with low substituted 1-allyloxy-2-hydroxypropyl-waxy maize starch (AHP-WMS; degree of substitution (DS) of 0.23) using hydrogen peroxide and acetonitrile Via a two step spectrophotometric assay,

  2. Cobalt(II chloride catalyzed one-pot synthesis of α-aminonitriles

    Directory of Open Access Journals (Sweden)

    De Surya K


    Full Text Available Abstract A simple and efficient method has been developed for the synthesis of α-aminonitriles by a one-pot three- component condensation of aldehydes, amines, and potassium cyanide in acetonitrile in the presence of a catalytic amount of CoCl2 at room temperature.

  3. Cobalt(II) chloride catalyzed one-pot synthesis of α-aminonitriles


    De, Surya K.


    Abstract A simple and efficient method has been developed for the synthesis of α-aminonitriles by a one-pot three- component condensation of aldehydes, amines, and potassium cyanide in acetonitrile in the presence of a catalytic amount of CoCl2 at room temperature.

  4. Understanding the complexation of Eu3+ with three diglycolamide-functionalized calix{4]arenes: spectroscopic and DFT studies

    NARCIS (Netherlands)

    Ansari, S.A.; Mohapatra, P.K.; Ali, S.M.; Sengupta, A; Bhattacharyya, A.; Verboom, W.


    Complexation of Eu3+ with three diglycolamide-functionalized calix[4]arene (C4DGA) ligands was investigated by UV-Vis and luminescence spectroscopy measurements in acetonitrile medium. The complexation thermodynamics was studied by micro-calorimetry while structural information was obtained from DFT

  5. Experimental Gas-Phase Thermochemistry for Alkane Reductive Elimination from Pt(IV)

    NARCIS (Netherlands)

    Couzijn, Erik P. A.; Kobylianskii, Ilia J.; Moret, Marc-Etienne; Chen, Peter


    The gas-phase reactivity of the [(NN)(PtMe3)-Me-IV](+) (NN = alpha-diimine) complex 1 and its acetonitrile adduct has been investigated by tandem mass spectrometry. The only observed reaction from the octahedral d(6) complex 1 center dot MeCN is the simple dissociation of the coordinated solvent mol

  6. Gated Photochromic System of Diarylethene with a Photon-Working Key. (United States)

    Mahvidi, Sadegh; Takeuchi, Sakiko; Kusumoto, Sara; Sato, Hiroyasu; Nakagawa, Tetsuya; Yokoyama, Yasushi


    Upon visible light irradiation, a thermally reversible photochromic acid generator merocyanine dye gives a proton to the dimethylamino group of a non-photochromic diarylethene in acetonitrile. The protonation rendered the non-photochromic diarylethene photochromic. Thus, the thermally irreversible photochromic nature of the diarylethene is activated without any physical contact or addition of any compound but only by photoirradiation to the merocyanine dye.

  7. Supported -pyrrolidine-2-carboxylic acid-4-hydrogen sulphate on silica gel as an economical and efficient catalyst for the one-pot preparation of -acetamido ketones via a four-component condensation reaction

    Indian Academy of Sciences (India)

    Arash Ghorbani-Choghamarani; Parisa Zamani


    An efficient, one-pot, four-component condensation of aldehydes, acetophenone (or propiophenone), acetyl chloride and acetonitrile in the presence of catalytic amounts of -pyrrolidine-2-carboxylic acid-4-hydrogen sulphate (supported on silica gel), a green and non-toxic catalyst, is described for the preparation of -acetamido ketones in good to excellent yields.

  8. A Mild and Highly Efficient Catalyst for Beckmann Rearrangement, BF3·OEt2

    Institute of Scientific and Technical Information of China (English)

    An Na; Pi Hongjun; Liu Lifeng; Du Wenting; Deng Weiping


    BF3·OEt2 (Boron trifluoride etherate), an inexpensive and commercially easily available Lewis acid stoichiometrically employed for Beckamann rearrangement in general, was now found to efficiently catalyze Beckmann rearrangement of ketoximes into their corresponding amides (up to 99% yield) in anhydrous acetonitrile under reflux temperature.

  9. Solvent-dependent regioselective oxidation of trans-chalcones using aqueous hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Wang; Jiabin, Yang; Lushen, Li, E-mail: [Southeast University, Nanjing (China). School of Biological Science and Medical Engineering; Jin, Cai; Chunlong, Sun; Min, Ji [Southeast University, Nanjing (China). School of Chemistry and Chemical Engineering


    A novel method for regioselective oxidation of trans-chalcones with hydrogen peroxide in acetonitrile to afford cinnamic acids is reported. Only trans-b-arylacrylic acids were observed. A wide range of functionalized products can be effectively produced from various chalcones in good to excellent yields. (author)

  10. Rapid sample preparation method for LC-MS/MS or GC-MS analysis of acrylamide in various food matrices. (United States)

    Mastovska, Katerina; Lehotay, Steven J


    A fast and easy sample preparation procedure for analysis of acrylamide in various food matrices was developed and optimized. In its first step, deuterated acrylamide internal standard is added to 1 g of homogenized sample together with 5 mL of hexane, 10 mL of water, 10 mL of acetonitrile, 4 g of MgSO4, and 0.5 g of NaCl. Water facilitates the extraction of acrylamide; hexane serves for sample defatting; and the salt combination induces separation of water and acetonitrile layers and forces the majority of acrylamide into the acetonitrile layer. After vigorous shaking of the extraction mixture for 1 min and centrifugation, the upper hexane layer is discarded and a 1 mL aliquot of the acetonitrile extract is cleaned up by dispersive solid-phase extraction using 50 mg of primary secondary amine sorbent and 150 mg of anhydrous MgSO4. The final extract is analyzed either by liquid chromatography-tandem mass spectrometry or by gas chromatography-mass spectrometry (in positive chemical ionization mode) using the direct sample introduction technique for rugged large-volume injection.

  11. Highly selective enrichment of phosphorylated peptides using titanium dioxide

    DEFF Research Database (Denmark)

    Thingholm, Tine; Jørgensen, Thomas J D; Jensen, Ole N


    a protocol for selective phosphopeptide enrichment using titanium dioxide (TiO2) chromatography. The selectivity toward phosphopeptides is obtained by loading the sample in a 2,5-dihydroxybenzoic acid (DHB) or phthalic acid solution containing acetonitrile and trifluoroacetic acid (TFA) onto a TiO2 micro...

  12. Photodimerization and photooxygenation of 9-vinylcarbazole catalyzed by titanium dioxide and magnesium perchlorate

    Institute of Scientific and Technical Information of China (English)

    Hajime; Maeda; Mio; Yamamoto; Hideyuki; Nakagawa; Kazuhiko; Mizuno


    Photoreaction of 9-vinylcarbazole in acetonitrile in the presence of titanium dioxide and a catalytic amount of magnesium perchlorate gave 3,6-di(9-carbazolyl)-1,2-dioxane as a photooxygenated product via photodimerization of 9-vinylcarbazole.The photoreaction proceeds via an electron transfer mechanism,where magnesium perchlorate accelerated formation of the photo-oxygenated product.

  13. Development and validation of a novel RP-HPLC method for simultaneous determination of paracetamol, phenylephrine hydrochloride, caffeine, cetirizine and nimesulide in tablet formulation

    Directory of Open Access Journals (Sweden)

    A.P. Dewani


    Full Text Available The present work describes development and validation of a high-performance liquid chromatography–diode array detection (HPLC–DAD procedure for the analysis of phenylephrine hydrochloride (PHE, paracetamol (PAR, caffeine anhydrous (CAF, cetirizine Dihydrochloride (CET, nimesulide (NIM in pharmaceutical mixture. Effective chromatographic separation of PHE, PAR, CAF, CET and NIM was achieved using a Kinetex-C18 (4.6 mm, 150 mm, 5 mm column with gradient elution of the mobile phase composed of 10 mM phosphate buffer (pH 3.3 and acetonitrile. The elution was a three step gradient elution program step-1 started initially with 2% (by volume acetonitrile and 98% phosphate buffer (pH 3.3 for first 2 min. In step-2 acetonitrile concentration changed linearly to 20% up to 12 min the analysis was concluded by step-3 changing acetonitrile to 2% up to 20 min. The proposed HPLC method was statistically validated with respect to linearity, ranges, precision, accuracy, selectivity and robustness. Calibration curves were linear in the ranges of 5–100, 100–1000 and 10–200 mg/mL for PHE, PAR, CAF, CET and NIM respectively, with correlation coefficients >0.9996. The HPLC method was applied to tablet dosage form in which the analytes were successfully quantified with good recovery values with no interfering peaks from the excipients.

  14. {Fe6O2}-Based Assembly of a Tetradecanuclear Iron Nanocluster

    Directory of Open Access Journals (Sweden)

    Svetlana G. Baca


    Full Text Available The tetradecanuclear FeIII pivalate nanocluster [Fe14O10(OH4(Piv18], comprising a new type of metal oxide framework, has been solvothermally synthesized from a hexanuclear iron pivalate precursor in dichlormethane/acetonitrile solution. Magnetic measurements indicate the presence of very strong antiferromagnetic interactions in the cluster core.

  15. Reactivity of β-Stannylketones. Elimination vs. Substitution

    Directory of Open Access Journals (Sweden)

    Ana Paula Murray


    Full Text Available In the present work we report the results obtained in the reaction of β-stannylketones (I with t-BuONa in dimethylsulfoxide (DMSO and acetonitrile (ACN as solvents. The reaction mechanisms probably involved are proposed.

  16. An ultra performance liquid chromatography-time-of-flight-mass spectrometric method for fast analysis of ginsenosides in Panax ginseng root

    NARCIS (Netherlands)

    Hu, C.; Kong, H.; Zhu, C.; Wei, H.; Hankemeier, T.; Greef, J. van der; Wang, M.; Xu, G.


    A method for fast analysis of ginsenosides in Panax ginseng roots was developed using ultra performance liquid chromatography-time-of-flight-mass spectrometry (UPLC-TOF-MS). The column used was HSS T3 (100 mm × 2.1 mm, 1.8 µm). The mobile phase consisted of 15 mmol/L ammonium formate and acetonitril

  17. Cosolvent Effect on the Tautomerism of Ethyl Acetoacetate in Supercritical CO2

    Institute of Scientific and Technical Information of China (English)


    The effect of cosolvent cyclohexane, chloroform, and acetonitrile on the keto-enol tautomeric equilibrium of ethyl acetoacetate in supercritical CO2 was studied by UV-Vis spectroscopy over the pressure range from 76 to 110 bar at 308.15 K. It was found that the equilibrium constant decreases with increasing polarity of the cosolvents.

  18. Biocatalytic synthesis of (R)-(-)-mandelic acid from racemic mandelonitrile by a newly isolated nitrilase-producer Alcaligenes sp. ECU0401

    Institute of Scientific and Technical Information of China (English)

    Yu Cai He; Jian He Xu; Yi Xu; Li Ming Ouyang; Jiang Pan


    By using acetonitrile as the sole nitrogen source, a microbial strain with high nitrilase activity, named as Alcaligenes sp.ECU0401, was newly isolated from soil, which could enantioselectively transform racemic mandelonitrile into (R)-(-)-mandelic acid, with an enantiomeric excess of>99.9%.

  19. Solvent selection for solid-to-solid synthesis

    NARCIS (Netherlands)

    Ulijn, R.V.; Martin, de L.; Gardossi, L.; Janssen, A.E.M.; Moore, B.D.; Halling, P.J.


    Thermolysin catalyzed solid-to-solid synthesis of the model peptide Z-L-Phe-L-Leu-NH2 is practically feasible in water and a range of organic solvents with different physicochemical properties. Excellent overall conversions were obtained in acetonitrile, ethyl acetate, n-hexane, methanol, 2-propanol

  20. 40 CFR 795.70 - Indirect photolysis screening test: Sunlight photolysis in waters containing dissolved humic... (United States)


    ... mobile phase is 2 percent acetic acid, 50 percent acetonitrile and 48 percent water (2 mL/min flow rate... of sunlight actinometers.” Environmental Science and Technology, 6:815. (1982). (6) Haag H.R., Hoigne... Science and Technology, 11:359. (1977). (20) Zepp, R.G., Wolfe N.L., Baughman G.L., Hollis R.C....

  1. An easy assembled fluorescent sensor for dicarboxylates and acidic amino acids

    Directory of Open Access Journals (Sweden)

    Albert W. M. Lee


    Full Text Available Two mesitylene based neutral receptors 1 and 2 bearing two thiourea binding sites were constructed as fluorescent probes for sensing dicarboxylates. Their binding affinities toward dicarboxylates, aspartate and glutamate have been investigated in acetonitrile solution by fluorescence titration experiments. Both fluorescent sensors exhibited some ability to discriminate the antipodal forms of aspartate and glutamate.

  2. Waste Water Handling Proof of Concepts at McMurdo Station, Antarctica (United States)


    2-Chlorotoluene Diisopropyl ether trans-1,3-Dichloropropene 2-Hexanone Ethyl acetate Trichloroethene 4-Ethyltoluene Ethylbenzene...Trichlorofluoromethane 4-Methyl-2-pentanone Ethyl tert-butyl ether Trichlorotrifluoroethane Acetone Heptane Vinyl acetate Acetonitrile Hexachlorobutadiene Vinyl... production at the runway was limited before the start of these projects and was estimated to determine proper sizing of the two methods used. During

  3. 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


    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 betwee

  4. Solvent-dependent regioselective oxidation of trans-chalcones using aqueous hydrogen peroxide



    A novel method for regioselective oxidation of trans-chalcones with hydrogen peroxide in acetonitrile to afford cinnamic acids is reported. Only trans-b-arylacrylic acids were observed. A wide range of functionalized products can be effectively produced from various chalcones in good to excellent yields.

  5. 293.15K时乙腈+水+[Hmim]Cl三元系统及其二元系统的折光率测定与关联%efractive Indices for Acetonitrile+Water+[Hmim]Cl and Its Binary Systems at 293.15 K

    Institute of Scientific and Technical Information of China (English)

    金胜哲; 郑叶玲; 何昌春; 彭昌军; 刘洪来


    主要通过折光率来研究离子液体对乙腈+水系统物理性质的影响。采用折光仪测定了乙腈+水+[Hmim]Cl(1-己基-3-甲基咪唑氯盐)三元系统及相应的乙腈+水、水+[Hmim]Cl、乙腈+[Hmim]Cl二元系统在293.15 K时的折光率,并获得了这些系统的过量折光率,建立了折光率与组成间的经验关系。结果表明,在全部浓度范围内过量折光率均为正值,且乙腈+水的折光率随组成变化出现极大值,而水+[Hmim]Cl、乙腈+[Hmim]Cl的折光率均随离子液体组成的增加而增加。用Redlich-Kister、Cibulka模型和Singh模型分别关联了二元和三元系统的过量折光率,证实可采用Kohler方程估算三元系统的折光率。%This work investigated the effect of ionic liquid on the physical properties of acetonitrile + water with the refractive indices,which were measured for the ternary system(acetonitrile + water + Cl(1-hexyl-3-methylimidazolium chloride)) and its binary systems(acetonitrile + water,water + Cl and acetonitrile + Cl) at 293.15 K by a refractometer.The excess refractive indices of the mixtures were obtained and the relationship of refractive indices with mole fractions was established with an empirical model.It was shown that the excess refractive indices were positive over the whole range of compositions,and there was a maximum for the refractive indices over the range of the investigated mole fraction in acetonitrile + water and the refractive indices in water + Cl and acetonitrile + Cl increased as the mole fraction of the ionic liquid increased.Furthermore,the excess refractive indices for the binary and ternary systems were fitted to the Redlich-Kister,Cibulka and Singh equations,respectively.As a result,the Kohler equation can successfully predict the refractive indices for the ternary system.

  6. Separation and identification of highly fluorescent compounds derived from trans-resveratrol in the leaves of Vitis vinifera infected by Plasmopara viticola. (United States)

    Tříska, Jan; Vrchotová, Naděžda; Olejníčková, Julie; Jílek, Rudolf; Sotolář, Radek


    A method for identification of highly fluorescent compounds in vine leaves infected by Plasmopara viticola was developed using reversed phase liquid chromatography with simultaneous diode array and fluorometric detection. Fluorescent compounds were extracted from leaves with a methanol-water mixture (70:30). Separation by HPLC was performed using a C(18) column and gradient elution with water-acetonitrile mixtures (20-80% of acetonitrile). The main unknown fluorescent compound was identified by line spectral comparison with a standard obtained by UV photoisomerization of trans-resveratrol glucoside, and its structure was confirmed by liquid chromatography-mass spectrometry. Identification and structural elucidation of the fluorescent compound in the leaves of Vitis vinifera allows early detection of Plasmopara viticola invasion.

  7. A kinetic study of the electron-transfer in the reaction of tribenzylchlorotin with [COW12O40]5-

    Institute of Scientific and Technical Information of China (English)

    Fatemeh F. Bamoharram; Mohammad M. Heravi; Touran Ardalan; Pouran Ardalan


    A kinetic study of the electron-transfer in the reaction of tribenzylchlorotin with potassium 12-tungsto cobalt (Ⅲ) ate ion, K5[CoW12O40], abbreviated as Co(Ⅲ)W, has been performed in different solvents. The studies were carried out in methanol, ethanol, acetonitrile and acetic acid/water. The rate constants, reaction rates and activation parameters were calculated. Our findings show that the rate of disappearance of the Co(Ⅲ) is pseudo-first order. The kinetic data is strongly affected by used solvents. The maximum and minimum rate constants were achieved in the ethanol and acetic acid/water (70/30) as a solvent, respectively. In all of the used solvents, negative value of activation entropies was observed, but negative activation enthalpies are observed in methanol, ethanol and acetonitrile. The reaction rate is increased with increase of Co(Ⅲ) concentration.

  8. How solvent modulates hydroxyl radical reactivity in hydrogen atom abstractions. (United States)

    Mitroka, Susan; Zimmeck, Stephanie; Troya, Diego; Tanko, James M


    The hydroxyl radical (HO*) is a highly reactive oxygen-centered radical whose bimolecular rate constants for reaction with organic compounds (hydrogen atom abstraction) approach the diffusion-controlled limit in aqueous solution. The results reported herein show that hydroxyl radical is considerably less reactive in dipolar, aprotic solvents such as acetonitrile. This diminished reactivity is explained on the basis of a polarized transition state for hydrogen abstraction, in which the oxygen of the hydroxyl radical becomes highly negative and can serve as a hydrogen bond acceptor. Because acetonitrile cannot participate as a hydrogen bond donor, the transition state cannot be stabilized by hydrogen bonding, and the reaction rate is lower; the opposite is true when water is the solvent. This hypothesis explains hydroxyl radical reactivity both in solution and in the gas phase and may be the basis for a "containment strategy" used by Nature when hydroxyl radical is produced endogenously.

  9. On the importance of vibrational contributions to small-angle optical rotation: Fluoro-oxirane in gas phase and solution (United States)

    Pedersen, Thomas Bondo; Kongsted, Jacob; Crawford, T. Daniel; Ruud, Kenneth


    The specific optical rotation of (S)-fluoro-oxirane in gas phase and solution is predicted using time-dependent density functional theory (B3LYP functional) and coupled cluster linear response theory. Upon vibrational averaging, the coupled cluster singles and doubles model predicts the gas phase specific optical rotation to be 8.1° (dm g/cm3)-1 at 355 nm at room temperature. This is an order of magnitude smaller than the B3LYP result of 68.4° (dm g/cm3)-1. The main source of this discrepancy is the electronic contribution at the equilibrium geometry. The effects of cyclohexane and acetonitrile solvents are calculated for both the electronic and vibrational contributions with the B3LYP functional. The specific optical rotation is estimated to change significantly depending on the polarity of the solvent, increasing in cyclohexane and decreasing in acetonitrile.

  10. Iron(III) porphyrin-catalysed oxidation reactions by -chloroperbenzoic acid: Nature of reactive intermediates

    Indian Academy of Sciences (India)

    A Agarwala; V Bagchi; D Bandyopadhyay


    The reaction of -chloroperbenzoic (-CPBA) acid with meso-tetrakis (pentafluorophenyl) porphynatoiron(III) chloride (F20TPPFe(III)Cl) has been studied in dichloromethane and acetonitrile medium at 25 ± 1° C. The reactive intermediates formed in this reaction have been quantitatively trapped by 2,4,6-tri -butylphenol (TTBP) in both the solvents. It has been observed that the kinetic plots of the formation of TTBP$^{\\bullet}$ radical in dichloromethane are all multiexponential, supporting the formation of more than one reactive intermediate in this solvent. In acetonitrile solvent the formation of TTBP$^{\\bullet}$ radical was however observed to be distinctly single exponential. Different kinds of reactive intermediates are proposed in these two solvents.

  11. Self-assembling monolayers of helical oligopeptides with applications in molecular electronics

    CERN Document Server

    Strong, A E


    prepared. Transformation of the two (Trt)Cys residues of the resin-bound peptide to the intramolecular disulphide by iodine was achieved in acetonitrile but not in DMF. CD suggested that the conformation of this peptide was a mixture of helix and random coil. Films of the peptide-disulphide and the peptide-dithiol adsorbed from protic solvents were characterised as multilayers by ellipsometry. However CV and ellipsometry showed that a monolayer was successfully prepared from acetonitrile. Future targets for improving and extending this method to form monolayers of linked disulphides are presented. The aim of this project was to develop a generic method of preparing a 'molecular architecture' containing functional groups on a surface at predetermined relative positions several nm apart. This would be of great utility in molecular electronics, chemical sensors and other fields. It was proposed that such an architecture could be prepared on gold using linked, helical oligopeptides that contained the components o...

  12. Synthesis of Some New Anils: Part 1. Reaction of 2-Hydroxy-benzaldehyde and 2-Hydroxynaphthaldehyde with 2-Aminopyridene and 2-Aminopyrazine

    Directory of Open Access Journals (Sweden)

    Khadija O. Badahdah


    Full Text Available New Schiff bases derived from 2-aminopyridene and 2-aminopyrazine have been synthesized. The UV-Visible spectra of the compounds have been investigated in acetonitrile and toluene. The compounds were in tautomeric equilibrium (enol-imine O– H···N, keto-amine O···H–N forms in polar and nonpolar solvents. For some derivatives the keto-amine form was observed in both toluene and acetonitrile. 1H-NMR and IR results showed that all Schiff bases studied favor the enol-imine form over the keto form in a weakly polar solvent such as deuterochloroform.

  13. Avaliação de solventes de extração por ultrassom usando-se cromatografia líquida de alta eficiência para a determinação de hidrocarbonetos policíclicos aromáticos em solos contaminados Evaluation of solvent extraction by ultrasound by using high performance liquid chromatography for the determination of polycyclic aromatic hydrocarbons in contaminated soils

    Directory of Open Access Journals (Sweden)

    Jussara Aparecida Oliveira Cotta


    Full Text Available A method using ultrasonication extraction for the determination of 17 polycyclic aromatic hydrocarbons (PAHs, selected by the USEPA and NIOSH as "consent decree" priority pollutants, in soil by High Performance Liquid Chromatography (HPLC was studied. Separation and detection were completed in 20 min with a C18 columm, acetonitrile-water gradient elution and ultraviolet absorption and fluorescence detections. The detection limits, for a 10 µL of solution injection, were less than 9,917 ng/g in UV detection and less than 1,866 ng/g in fluorescence detection. Several organic solvents were tested for extraction of the 17 PAHs from soils. Acetone was the best solvent among the three solvents tested, and the order of the extraction efficiencies was: acetone>methanol>acetonitrile. Ultrasonication using acetone as solvent extraction was used to evaluate the biodegradation of those compounds in contaminated soil during a vermicomposting process.

  14. Simultaneous Quantification of Antidiabetic Agents in Human Plasma by a UPLC–QToF-MS Method (United States)

    Fachi, Mariana Millan; Cerqueira, Letícia Bonancio; Leonart, Letícia Paula; de Francisco, Thais Martins Guimarães


    An ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry method for the simultaneous quantification of chlorpropamide, glibenclamide, gliclazide, glimepiride, metformin, nateglinide, pioglitazone, rosiglitazone, and vildagliptin in human plasma was developed and validated, using isoniazid and sulfaquinoxaline as internal standards. Following plasma protein precipitation using acetonitrile with 1% formic acid, chromatographic separation was performed on a cyano column using gradient elution with water and acetonitrile, both containing 0.1% formic acid. Detection was performed in a quadrupole time-of-flight analyzer, using electrospray ionization operated in the positive mode. Data from validation studies demonstrated that the new method is highly sensitive, selective, precise (RSD 0.99), free of matrix and has no residual effects. The developed method was successfully applied to volunteers’ plasma samples. Hence, this method was demonstrated to be appropriate for clinical monitoring of antidiabetic agents. PMID:27930700

  15. Molecular dynamics study of solvation effects on acid dissociation in aprotic media

    CERN Document Server

    Laria, D; Estrin, D A; Ciccotti, G; Laria, Daniel; Kapral, Raymond; Estrin, Dario; Ciccotti, Giovanni


    Acid ionization in aprotic media is studied using Molecular Dynamics techniques. In particular, models for HCl ionization in acetonitrile and dimethylsulfoxide are investigated. The proton is treated quantum mechanically using Feynman path integral methods and the remaining molecules are treated classically. Quantum effects are shown to be essential for the proper treatment of the ionization. The potential of mean force is computed as a function of the ion pair separation and the local solvent structure is examined. The computed dissociation constants in both solvents differ by several orders of magnitude which are in reasonable agreement with experimental results. Solvent separated ion pairs are found to exist in dimethylsulfoxide but not in acetonitrile. Dissociation mechanisms in small clusters are also investigated. Solvent separated ion pairs persist even in aggregates composed of rather few molecules, for instance, as few as thirty molecules. For smaller clusters or for large ion pair separations cluste...

  16. The Effects of Solvent and Added Bases on the Protection of Benzylamines with Carbon Dioxide

    Directory of Open Access Journals (Sweden)

    Amy L. Ethier


    Full Text Available The introduction and removal of protecting groups is ubiquitous in multi-step synthetic schemes. From a green chemistry standpoint, however, alternative strategies that employ in situ and reversible protection and deprotection sequences would be attractive. The reversible reactions of CO2 with amines could provide a possible vehicle for realizing this strategy. Herein, we present (1 the products of reaction of benzylamines with CO2 in a variety of solvents with and without the presence of basic additives; (2 new adducts associated with CO2 protected benzylamine in acetonitrile containing 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU; and (3 the intermolecular competitive acylation of benzylamine and benzyl alcohol and the intramolecular competitive acylation of (4-aminomethylphenyl methanol with isopropenyl acetate in acetonitrile containing DBU in the absence and presence of CO2.

  17. Novel Monomeric Phenanthroline—Thallium(Ⅲ) Complexes Multinuclear NMR Characterization in Organic Solvents

    Institute of Scientific and Technical Information of China (English)

    GuiBinMA; JuliusGLASER


    A novel complex of monomeric thallium (Ⅲ) with the nitrogen donor ligand phenanthroline (phen) has been prepared and characterized by multimuclear NMR(1H,13C,205Tl). The three complexes exist in equilibria in DMSO and acetonitrile solution, which was proved by the 205Tl NMR spectra. The 1H and 13C NMR spectra of tris-phen T1(Ⅲ) complex have been measured, where the spin-spin coupling between T1(I=1/2) and 13C or 1H signals were observed with the 1H and 13C NMR spectroscopy in acetonitrile. The coupling constants are presented and the chemical shifts of complexes are discussed in detail.

  18. Novel Monomeric Phenanthroline - Thallium(Ⅲ) Complexes Multinuclear NMR Characterization in Organic Solvents

    Institute of Scientific and Technical Information of China (English)


    A novel complex of monomeric thallium(III) with the nitrogen donor ligand phenanthrolinc (phen) has been prepared and characterized by multinuclear NMR (1H, 13C, 205T1).The three complexes exist in equilibria in DMSO and acetonitrile solution, which was proved by the 205Tl NMR spectra. The 1H and 13C NMR spectra of tris-phen Tl(III) complex have been measured, where the spin-spin coupling between TI (1 = 1/2) and 13C or 1H signals were observed with the 1H and 13C NMR spectroscopy in acetonitrile. The coupling constants are presented and the chemical shifts of complexes are discussed in detail.

  19. Analytical Method Development and Validation of Related Substance Method for Bortezomib for Injection 3.5 mg/Vial by RP-HPLC Method

    Directory of Open Access Journals (Sweden)

    Utage M


    Full Text Available An accurate, precise, simple and economical High Performance Liquid Chromatographic method for therelated substance determination of Bortezomib in its lyophilized dosage form has been developed. Themethod developed is Reverse Phase High Performance Liquid Chromatographic method using HypersilBDS C18 column (Length: 150mm, Diameter: 4.6mm, Particle size: 5μ with Gradient programmed anda simple Acetonitrile, Water and Formic acid in the ratio of 30:70:0.1 (v/v/v respectively as mobilephase A and Acetonitrile, Water and Formic acid in the ratio of 80:20:0.1 (v/v/v respectively. Themethod so developed was validated in compliance with the regulatory guidelines by using welldeveloped analytical method validation tool which comprises with the analytical method validationparameters like Linearity, Accuracy, Method precision, Specificity with forced degradation, Systemsuitability, Robustness, LOD, LOQ and Ruggedness. The results obtained were well within theacceptance criteria.

  20. Time-resolved photoisomerization of 1,1‧-di-tert-butylstilbene and 1,1‧-dicyanostilbene (United States)

    Dobryakov, A. L.; Quick, M.; Lenoir, D.; Detert, H.; Ernsting, N. P.; Kovalenko, S. A.


    Photoisomerization of 1,1‧-di-tert-butylstilbene (3) and 1,1‧-dicyanostilbene (4) is monitored with stationary and broadband transient absorption spectroscopy. The electron affinity of the substituents correlates with the shift of the absorption band. The weak extinction of 3 complicates data interpretation, but comparison with earlier measured 1,1‧-dimethylstilbene (1) and 1,1‧-diethylstilbene (2) helps to assign transient spectra and relaxation paths. For 3 a long-lived perpendicular state P is observed with lifetime τP = 134 ps in acetonitrile. For 4τP = 2.1 ps in acetonitrile and 27 ps in n-hexane, the difference indicating a substantial dipole moment (∼3D) of the P state.

  1. Quantitative determination of amisulpride in rat plasma by HPLC-MS/MS. (United States)

    Noh, Keumhan; Jang, Yoo-Jeong; Kwon, Kwang-il; Kim, Eunyoung; Jeong, Tae Cheon; Yun, Hwi-yeol; Kang, Wonku


    Amisulpride, a selective antagonist of D2 and D3 dopamine receptors, is used as an antipsychotic drug. In this study, we reported a sensitive LC-MS/MS method for determining amisulpride concentrations in rat plasma, and a preclinical pharmacokinetic study in the rat. After a simple protein precipitation with acetonitrile containing methaqualone as an internal standard, the analytes were separated on a reversed-phase column with a mobile phase of 0.2 % aqueous formic acid and acetonitrile (3:7, v/v). The accuracy and precision of the assay were in accordance with FDA guidance for the validation of bioanalytical methods. This analytical method was used successfully to characterize the time course of the plasma concentration of amisulpride following oral administration of a single 10 mg/kg dose in rats.

  2. Spectroscopic characterization of mechanisms of oxidation of Phe by SO.-4 radical: A pulse radiolysis study

    Institute of Scientific and Technical Information of China (English)

    储高升; 张淑娟; 姚思德; 韩镇辉; 都志文; 张志成


    By using time-resolved kinetic spectrophotometry and pulse radiolysis technique, the oxidation of Phe by radical has been investigated both in aqueous and water/acetonitrile mixed solutions. The results reveal that attack of the oxidizing SO4-radical on Phe leads directly to the formation of Phe cation radical 3 with a strong absorption peak at 310 nm, then it proceeds in three competitive reactions via either hydroxylation, deprotonation or decarboxylation, which were found to be strongly dependent upon the ionization state of the substitutes -COOH and -NH2 and the nature of the solvents. Decarboxylation takes place only when the carboxyl group is deprotonated. At high pH deprotonation of Phe cation radical 3 is much easier to occur than that in neutral or acid solutions. Moreover, with addition of acetonitrile, deprotonation is more predominant than hydroxylation, whereas in aqueous solutions hydroxylation is much easier to occur.

  3. Quantification of the Triazole Antifungal Compounds Voriconazole and Posaconazole in Human Serum or Plasma Using Liquid Chromatography Electrospray Tandem Mass Spectrometry (HPLC-ESI-MS/MS). (United States)

    Molinelli, Alejandro R; Rose, Charles H


    Voriconazole and posaconazole are triazole antifungal compounds used in the treatment of fungal infections. Therapeutic drug monitoring of both compounds is recommended in order to guide drug dosing to achieve optimal blood concentrations. In this chapter we describe an HPLC-ESI-MS/MS method for the quantification of both compounds in human plasma or serum following a simple specimen preparation procedure. Specimen preparation consists of protein precipitation using methanol and acetonitrile followed by a cleanup step that involves filtration through a cellulose acetate membrane. The specimen is then injected into an HPLC-ESI-MS/MS equipped with a C18 column and separated over an acetonitrile gradient. Quantification of the drugs in the specimen is achieved by comparing the response of the unknown specimen to that of the calibrators in the standard curve using multiple reaction monitoring.

  4. Substrate Directed Regioselective Monobromination of Aralkyl Ketones Using N-Bromosuccinimide Catalysed by Active Aluminium Oxide: α -Bromination versus Ring Bromination. (United States)

    Mohan, Reddy Bodireddy; Reddy, G Trivikram; Gangi Reddy, N C


    Bromination of aralkyl ketones using N-bromosuccinimide in presence of active Al2O3 provided either α -monobrominated products in methanol at reflux or mononuclear brominated products in acetonitrile at reflux temperature with excellent isolated yields depending on the nature of substrate employed. The α -bromination was an exclusive process when aralkyl ketones containing moderate activating/deactivating groups were subjected to bromination under acidic Al2O3 conditions in methanol at reflux while nuclear functionalization was predominant when aralkyl ketones containing high activating groups were utilized for bromination in presence of neutral Al2O3 conditions in acetonitrile at reflux temperature. In addition, easy isolation of products, use of inexpensive catalyst, short reaction time (10-20 min), and safe operational practice are the major benefits in the present protocol.

  5. X-ray characterization of tripyridinium bis[tetrabromidoferrate(III)] bromide asymmetric unit in solution by Debye function analysis (United States)

    Baniasadi, F.; Sahraei, N.; Fathi, M. B.; Tehranchi, M. M.; Safari, N.; Amani, V.


    Abundant asymmetric unit of the [FeBr4]2[py.H]3Br magnetic molecule in the acetonitrile solvent was characterized via Debye function analysis (DFA) of the X-ray powder diffraction pattern from dilute solution. A diluted solution of the material in acetonitrile solvent has been prepared to reduce, as far as possible, the interaction between the molecular units. The X-ray diffraction from the sample was measured and Debye function simulations of three out of ten chemically plausible molecular units were observed to suitably comply with the experimental results. These three configurations were further optimized with first-principles method in the framework of density functional theory (DFT) and the most stable structure according to the calculated total energy is presented.

  6. Determination of organic acids during the fermentation and cold storage of yogurt. (United States)

    Fernandez-Garcia, E; McGregor, J U


    The objective of the present study was the separation and quantification of orotic, citric, pyruvic, lactic, uric, formic, acetic, propionic, butyric, and hippuric acids in a single isocratic analysis by HPLC. Two methods of extraction were compared: 1) acetonitrile and water and 2) .01N H2SO4. Recoveries of orotic, lactic, acetic, and propionic acids were 90% for both methods. Recoveries of citric, pyruvic, uric, butyric, and hippuric acids were not satisfactory with the acetonitrile method, but were acceptable using the H2SO4 extraction procedure. Yogurts were manufactured under laboratory-scale conditions, and samples were analyzed during fermentation and after storage at 4 degrees C. Samples were analyzed for pH and organic acids. All of the organic acids exhibited varying degrees of increases and decreases during fermentation and storage. Formic and butyric acids were not detected under the conditions of this study.

  7. Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil. (United States)

    Theobald, A; Simoneau, C; Hannaert, P; Roncari, P; Roncari, A; Rudolph, T; Anklam, E


    The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPLC with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1 mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether) analysed in the same products in the context of a previous study.

  8. Prediction of the chromatographic retention of acid-base compounds in pH buffered methanol-water mobile phases in gradient mode by a simplified model. (United States)

    Andrés, Axel; Rosés, Martí; Bosch, Elisabeth


    Retention of ionizable analytes under gradient elution depends on the pH of the mobile phase, the pKa of the analyte and their evolution along the programmed gradient. In previous work, a model depending on two fitting parameters was recommended because of its very favorable relationship between accuracy and required experimental work. It was developed using acetonitrile as the organic modifier and involves pKa modeling by means of equations that take into account the acidic functional group of the compound (carboxylic acid, protonated amine, etc.). In this work, the two-parameter predicting model is tested and validated using methanol as the organic modifier of the mobile phase and several compounds of higher pharmaceutical relevance and structural complexity as testing analytes. The results have been quite good overall, showing that the predicting model is applicable to a wide variety of acid-base compounds using mobile phases prepared with acetonitrile or methanol.

  9. Novel Reaction of N,N'-Bisarylmethanediamines with Formaldehyde. Synthesis of Some New 1,3,5-Triaryl-1,3,5-hexahydrotriazines

    Directory of Open Access Journals (Sweden)

    Abolfazl Olyaei


    Full Text Available The acid-catalyzed cyclocondensation of N,N'-bisaryl (aryl = 2-pyrimidinyl, 2- pyrazinyl and 4-nitrophenyl methanediamines 5a-c with aqueous formaldehyde in refluxing acetonitrile leads to the formation of the corresponding 1,3,5-triaryl-1,3,5-hexa- hydrotriazines 6a-c. The stoichiometric reactions of 2-aminopyrimidine and 2-amino- pyrazine with aqueous formaldehyde in acetonitrile under reflux conditions also afforded 6a and 6b, respectively. Treatment of 2-aminopyrimidine with aqueous formaldehyde in a 3:2 ratio yielded N,N',N"-tris(2-pyrimidinyldimethylenetriamine (7a as a sole product, which upon subsequent reaction with formaldehyde also afforded 6a. The reaction of N,N'-biphenylmethanediamine with formaldehyde was also investigated.

  10. Influence of temperature and electrolyte on the performance of activated-carbon supercapacitors (United States)

    Liu, Ping; Verbrugge, Mark; Soukiazian, Souren

    For hybrid electric vehicle traction applications, energy storage devices with high power density and energy efficiency are required. A primary attribute of supercapacitors is that they retain their high power density and energy efficiency even at -30 °C, the lowest temperature at which unassisted starting must be provided to customers. More abuse-tolerant electrolytes are preferred to the high-conductivity acetonitrile-based systems commonly employed. Propylene carbonate based electrolytes are a promising alternative. In this work, we compare the electrochemical performance of two high-power density electrical double layer supercapacitors employing acetonitrile and propylene carbonate as solvents. From this study, we are able to elucidate phenomena that control the resistance of supercapacitor at lower temperatures, and quantify the difference in performance associated with the two electrolytes.

  11. Transformation of Oximes and Alcohols to Carbonyl Compounds Using Amberlite IRA-400 Supported Chromic Acid in the Presence of Zirconium Tetrachloride

    Institute of Scientific and Technical Information of China (English)

    BAHRAMI, Kiumars; KHODAEIMohammad-Mehdi; GORGIN-KARAJI, Usef


    A wide variety of oximes and alcohols were efficiently converted to their corresponding aldehydes and ketones in good to excellent yields using amberlite IRA-400 supported chromic acid in the presence of zirconium tetrachlo-ride in refluxing acetonitrile-H2O. Selective oxidation of oximes and alcohols in the presence of other functional groups such as acetal, hydrazone, aldehyde, ether and alkene can be considered as a noteworthy advantage of this method. A wide variety of oximes and alcohols were efficiently converted to their corresponding aldehydes and ke-tones in good to excellent yields using amberlite IRA-400 supported chromic acid in the presence of zirconium tet-rachloride in refluxing acetonitrile-H2O. Selective oxidation of oximes and alcohols in the presence of other func-tional groups such as acetal, hydrazone, aldehyde, ether and alkene can be considered as a noteworthy advantage of this method.


    Directory of Open Access Journals (Sweden)



    Full Text Available Electrical double layer and electrochemical characteristics at the nanoporous carbon | (C2H54NBF4 + acetonitrile interface have been studied by the cyclic voltammetry and impedance spectroscopy methods. The value of zero charge potential (0.23 V vs. SCE in H2O, the region of ideal polarizability and other characteristics have been established. Analysis of complex plane plots shows that the nanoporous carbon | x M (C2H54NBF4 + acetonitrile interface can be simulated by the equivalent circuit, in which the two parallel conduction parts in the solid and liquid phases are interconnected by the double layer capacitance in parallel with the complex admittance of hindered reaction of the charge transfer process. The values of the characteristic frequency depend on the electrolyte concentration and on the electrode potential, i.e. on the nature of ions adsorbed at the surface of nanoporous carbon electrode.

  13. Solid-phase extraction and liquid chromatographic quantitation of quinfamide in biological samples. (United States)

    Morales, J M; Jung, C H; Alarcón, A; Barreda, A


    This paper describes a high-performance liquid chromatographic method for the assay of quinfamide and its main metabolite, 1-(dichloroacetyl)-1,2,3,4,-tetrahydro-6-quinolinol, in plasma, urine and feces. It requires 1 ml of biological fluid, an extraction using Sep-Pack cartridges and acetonitrile for drug elution. Analysis was performed on a CN column (5 microm) using water-acetonitrile-methanol (40:50:10) as a mobile phase at 269 nm. Results showed that the assay was linear in the range between 0.08 and 2.0 microg/ml. The limit of quantitation was 0.08 microg/ml. Maximum assay coefficient of variation was 14%. Recovery obtained in plasma, urine and feces ranged from 82% to 98%.

  14. Validation and statistical analysis of two high performance liquid chromatography methods for the determination of indinavir sulfate raw material and capsules

    Directory of Open Access Journals (Sweden)

    Breno de Carvalho e Silva


    Full Text Available Two high performance liquid chromatography (HPLC methods for the quantitative determination of indinavir sulfate were tested, validated and statistically compared. Assays were carried out using as mobile phases mixtures of dibutylammonium phosphate buffer pH 6.5 and acetonitrile (55:45 at 1 mL/min or citrate buffer pH 5 and acetonitrile (60:40 at 1 mL/min, an octylsilane column (RP-8 and a UV spectrophotometric detector at 260 nm. Both methods showed good sensitivity, linearity, precision and accuracy. The statistical analysis using the t-student test for the determination of indinavir sulfate raw material and capsules indicated no statistically significant difference between the two methods.

  15. Making oxidation potentials predictable: Coordination of additives applied to the electronic fine tuning of an iron(II) complex

    KAUST Repository

    Haslinger, Stefan


    This work examines the impact of axially coordinating additives on the electronic structure of a bioinspired octahedral low-spin iron(II) N-heterocyclic carbene (Fe-NHC) complex. Bearing two labile trans-acetonitrile ligands, the Fe-NHC complex, which is also an excellent oxidation catalyst, is prone to axial ligand exchange. Phosphine- and pyridine-based additives are used for substitution of the acetonitrile ligands. On the basis of the resulting defined complexes, predictability of the oxidation potentials is demonstrated, based on a correlation between cyclic voltammetry experiments and density functional theory calculated molecular orbital energies. Fundamental insights into changes of the electronic properties upon axial ligand exchange and the impact on related attributes will finally lead to target-oriented manipulation of the electronic properties and consequently to the effective tuning of the reactivity of bioinspired systems.

  16. Determination of metformin and its prodrugs in human and rat blood by hydrophilic interaction liquid chromatography. (United States)

    Huttunen, Kristiina M; Rautio, Jarkko; Leppänen, Jukka; Vepsäläinen, Jouko; Keski-Rahkonen, Pekka


    Simple and specific hydrophilic interaction liquid chromatography (HILIC) method with ultraviolet (UV) detection was developed for the simultaneous determination of highly water-soluble metformin and its more lipophilic prodrugs in human and rat blood samples. The sample preparation was accomplished by precipitating proteins with acetonitrile, which enabled the direct injection of supernatants to the HPLC. Chromatographic separation was performed on an analytical normal phase silica column using a mixture of 0.01 M ammonium acetate pH 5.0 and acetonitrile (40:60, v/v) as a mobile phase at flow rate of 1 ml/min and at the wavelength of 235 nm. The method was validated in terms of specificity, linearity, accuracy, precision, recovery, and analyte stability. The UV-HILIC method was suitable for detecting both metformin and one of its more lipophilic prodrugs simultaneously in human and rat blood samples.

  17. Retention behavior of phenols, anilines, and alkylbenzenes in liquid chromatographic separations using subcritical water as the mobile phase. (United States)

    Yang, Y; Jones, A D; Eaton, C D


    The unique characteristic of subcritical water is its widely tunable physical properties. For example, the polarity (measured by dielectric constant) of water is significantly decreased by raising water temperature. At temperatures of 200-250 °C (under moderate pressure to keep water in the liquid state), the polarity of pure water is similar to that of pure methanol or acetonitrile at ambient conditions. Therefore, pure subcritical water may be able to serve as the mobile phase for reversed-phase separations. To investigate the retention behavior in subcritical water separation, the retention factors of BTEX (benzene, toluene, ethylbenzene, and m-xylene), phenol, aniline, and their derivatives have been determined using subcritical water, methanol/water, and acetonitrile/water systems. Subcritical water separations were also performed using alumina, silica-bonded C18, and poly(styrene-divinylbenzene) columns to study the influence of the stationary phase on analyte retention under subcritical water conditions.

  18. Detection of malondialdehyde in processed meat products without interference from the ingredients. (United States)

    Jung, Samooel; Nam, Ki Chang; Jo, Cheorun


    Our aim was to develop a method for accurate quantification of malondialdehyde (MDA) in meat products. MDA content of uncured ground pork (Control); ground pork cured with sodium nitrite (Nitrite); and ground pork cured with sodium nitrite, sodium chloride, sodium pyrophosphate, maltodextrin, and a sausage seasoning (Mix) was measured by the 2-thiobarbituric acid (TBA) assay with MDA extraction by trichloroacetic acid (method A) and two high-performance liquid chromatography (HPLC) methods: i) HPLC separation of the MDA-dinitrophenyl hydrazine adduct (method B) and ii) HPLC separation of MDA (method C) after MDA extraction with acetonitrile. Methods A and B could not quantify MDA accurately in groups Nitrite and Mix. Nevertheless, MDA in groups Control, Nitrite, and Mix was accurately quantified by method C with good recovery. Therefore, direct MDA quantification by HPLC after MDA extraction with acetonitrile (method C) is useful for accurate measurement of MDA content in processed meat products.

  19. Validated specific HPLC methods for determination of prazosin, terazosin and doxazosin in the presence of degradation products formed under ICH-recommended stress conditions. (United States)

    Bakshi, Monika; Ojha, Tina; Singh, Saranjit


    The present paper describes development of stability-indicating high-performance liquid chromatographic (HPLC) assay methods for three alpha-adrenergic-blocker drug substances, namely, prazosin, terazosin and doxazosin, in the presence of degradation products generated from forced decomposition studies. Resolution of drugs from degradation products was obtained using a reversed-phase C-18 column using water/acetonitrile/methanol/glacial acetic acid/diethylamine (25:35:40:1:0.017) as mobile phase for prazosin and terazosin and acetonitrile/water/glacial acetic acid/diethylamine (65:35:1:0.02) for doxazosin. The detection was done at 254 nm. The methods were validated with respect to linearity, precision, accuracy, specificity and robustness.

  20. Enantioseparation of Neutral Compounds on a Quinine Carbamate-Immobilized Zirconia in Reversed-Phase Capillary Electrochromatography

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Mun Rak; Gwon, Ju Rim; Park, Jung Hag [Yeungnam University, Gyeongsan (Korea, Republic of)


    Quinine (QN) is a weak anion-exchange type chiral selector and QN-based silica stationary phases have been widely used for enantioseparation of acidic chiral analytes in HPLC and recently in CEC. In this work we report enantioseparation of non-acidic chiral analytes on a quinine carbamate-immobilized zirconia (QNZ) in reversed-phase (RP) CEC. Influences of pH, composition of the buffer, acetonitrile content and the applied voltage on enantioseparation were examined. Enantiomers of the analytes investigated are well separated in acetonitrile/phosphate buffer mobile phases. Separation data on QNZ were compared to those on QN-bonded silica (QNS). Retention was longer but better enantioselectivity and resolution were obtained on QNZ than QNS.

  1. Determination of related substances in lisinopril and amlodipine tablets by HPLC

    Institute of Scientific and Technical Information of China (English)

    Dao-Rui Yu; Gui-Fang Yang; Wen-Li Xiao; Jun Wang; Qi-Bing Liu


    Objective:To establish an HPLC method for determining the related substances in lisinopril and amlodipine tablets.Methods:An Inertsil Thermo BDS HYPERSIL C18 (4.6 mmí250 mm, 5 μm) column was used with the Acetonitrile-water-phosphoric acid (10:90:0.1) as mobile phase A and Acetonitrile-water-phosphoric acid (90:10:0.1) as mobile phase B by gradient elution at the detection wavelength of 215 nm. The flow rate was 1.0 mL/min and the column temperature was 30℃.Results: The separation of the impurity peak and peak was good. Besides, all the impurities could be detected effectively.Conclusions:The method is sensitive, accurate and selective. It is suitable for control the related substances in lisinopril and Amlodipine tablets.

  2. Solvent-dependent oxidations of 5- and 6-azaindoles to trioxopyrrolopyridines and functionalised azaindoles. (United States)

    Mahiout, Zahia; Lomberget, Thierry; Goncalves, Sylvie; Barret, Roland


    A regioselective synthesis of 4,7-dimethoxy 5- and 6-azaindoles 2 has been achieved, based on the appropriate choice of ortho-directing or ortho-repulsing groups in the formylation of a pyridine ring. Studies on the regioselectivity of the formylation step and on the preparation of azidoacrylate intermediates 4 are described in this paper. The reactivity of the 5- and 6-azaindole structures towards BBr3-mediated selective monodemethylation and oxidative demethylation reactions were also investigated. The regioselectivity of the deprotection was confirmed using a chemical approach. Oxidation reactions were then carried out on either dimethoxy- or hydroxymethoxyazaindoles, in different solvents, using [bis(trifluoroacetoxy)iodo]benzene. In acetonitrile-water, trioxopyrrolopyridines 12 were obtained, whereas the formation of functionalised azaindoles 17 was observed in acetonitrile-methanol. The tautomeric structure of the trioxopyrrolopyridines was proved by X-ray diffraction analysis.

  3. Development and Characterization of Reactive Triangulenium Chromophores for Bioconjugation Applications

    DEFF Research Database (Denmark)

    Bora, Ilkay

    With the continuing development of advanced fluorescence techniques such as single-molecule fluorescence, time-gated detection, multiple laser pulse excitation, anisotropy decay assays and quenching experiments, fluorescent dyes are needed whose focus does not only lie on classic emission amplitude.......66 in acetonitrile. Their saliently high lifetimes of up to 23 ns in acetonitrile allow for autofluorescence eliminating time-gated measurements; combined with their strongly polarized transitions they enable the measurement of slow protein dynamics. Synthetic strategies developed by Laursen and Krebs allow...... maleimides were introduced into the azadioxa- and diazaoxa-triangulenium chromophores. The effect of the linker rigidity on the local mobility of the fluorophore on protein surfaces and the resulting retardation of initial emission anisotropy loss in time-resolved experiments were then investigated...

  4. Separations by gradient elution: why are steep gradient profiles distorted and what is their impact on resolution in reversed-phase liquid chromatography. (United States)

    Gritti, Fabrice; Guiochon, Georges


    The formation of a concentration shock layer of either methanol or acetonitrile used as the modifier in steep RPLC aqueous/organic gradients was predictable from their excess adsorption isotherm and was directly observed from their elution profiles recorded in UV absorption. A discontinuity of the concentration profile of the organic modifier arises and grows along the column. Its effects on the peak shapes and the resolution levels achieved in steep gradient chromatography were measured in the recorded chromatograms of a sample mixture containing 14 different analytes uniformly distributed across the gradient retention window. The results showed severe peak shape deformation for some compounds and a significant degradation of the baseline resolution of weakly (when using acetonitrile) and moderately (when using methanol) retained analytes. Solutions to limit this loss of resolution may lie in changing the initial gradient conditions or in adjusting the curvature of the gradient profile at the column inlet.

  5. Determinação de resíduos de pesticidas em plasma bovino por cromatografia gasosa-espectrometria de massas Pesticides residue determination in cattle plasma by gas chromatography-mass spectrometry

    Directory of Open Access Journals (Sweden)

    Daniele Fernanda Maffei


    Full Text Available An analytical method for the isolation based on matrix solid-phase dispersion technique and gas chromatographic determination of pesticides in cattle plasma is presented. It was fortified 0.25 g of plasma with pesticides and blended with 1 g each C18 and Na2SO4. The homogenized matter was transferred to a SPE cartridge, which contained 1 g of activated florisil with 5 mL acetonitrile. The analites were eluted under vaccum with 15 mL acetonitrile, the extract was analyzed by gas chromatography-mass spectrometry. The limit of quantification of the method was 0.04 mg L-1 for chlorphenvinfos and fipronil and 0.02 mg L-1 for cypermethrin..

  6. Optimized IMAC-IMAC protocol for phosphopeptide recovery from complex biological samples

    DEFF Research Database (Denmark)

    Ye, Juanying; Zhang, Xumin; Young, Clifford;


    that the ionization efficiencies of the phosphoryl group and carboxylic group changed differently when the acetonitrile concentration was increased. A magnified difference was achieved in high acetonitrile content solutions. On the basis of this concept, an optimized phosphopeptide enrichment protocol was established...... using Fe(III)-NTA IMAC resin and it proved to be highly selective in the phosphopeptide enrichment of a highly diluted standard sample (1:1000) prior to MALDI MS analysis. We also observed that a higher iron purity led to an increased IMAC enrichment efficiency. The optimized method was then adapted...... peptides from singly phosphorylated peptides with successive IMAC enrichments. The rational improvements to the IMAC protocol described in this study provide more insights into the factors that affect IMAC performance for phosphopeptide recovery. The improved IMAC-IMAC method should allow more detailed...

  7. Liquid chromatographic determination of furazolidone in shrimp. (United States)

    Stehly, G R; Plakas, S M; el Said, K R


    A liquid chromatographic (LC) method was developed for the quantitation of furazolidone residues in shrimp muscle. The shrimp homogenate (1.0 g) is extracted with acetonitrile, and the extract is taken to dryness. The residue is dissolved in acetonitrile, and the solution is passed through alumina and C18 cleanup columns. The eluate is taken to dryness and reconstituted in a suitable solvent for reversed-phase (C18) LC with UV detection at 365 nm. Recoveries of furazolidone from shrimp homogenates spiked from 5 to 80 ng/g ranged from 74.3 to 79.7%, and relative standard deviations (RSDs) were 5.0-8.9%. RSDs for incurred furazolidone quantitated at 5.9 and 9.2 ng/g were 6.6 and 7.6%, respectively.

  8. Determination of spirocyclic tetronic/tetramic acid derivatives and neonicotinoid insecticides in fruits and vegetables by liquid chromatography and mass spectrometry after dispersive liquid-liquid microextraction. (United States)

    Pastor-Belda, Marta; Garrido, Isabel; Campillo, Natalia; Viñas, Pilar; Hellín, Pilar; Flores, Pilar; Fenoll, José


    Dispersive liquid-liquid microextraction was used to preconcentrate three spirocyclic tetronic/tetramic acid derivatives (spirotetramat, spiromesifen and spirodiclofen) and five neonicotinoid (thiamethoxam, chlotianidin, imidacloprid, acetamiprid and thiacloprid) insecticides previously extracted from fruit and vegetable matrices with acetonitrile. The organic enriched phase was evaporated, reconstituted in 25μL acetonitrile and analyzed by reversed-phase liquid chromatography with tandem mass spectrometry using a triple quadrupole in selected reaction monitoring mode. Enrichment factors in the 15-100 range were obtained. A matrix effect was observed, the detection limits varying between 0.025 and 0.5ngg(-1), depending on the compound and the sample matrix. The developed method was applied to the analysis of 25 samples corresponding to five different fruit and vegetable matrices. Only thiamethoxam was detected in a lemon sample at a concentration close to the quantification limit, and spiromesifen and spirotetramat at concentrations between 11.6 and 54.5ngg(-1).

  9. Influence of Solvent on Reaction Path to Synthesis of Methyl N-Phenyl Carbamate from Aniline, CO2 and Methanol

    Institute of Scientific and Technical Information of China (English)

    安华良; 张丽丽; 苑保国; 赵新强; 王延吉


    Methyl N-phenyl carbamate (MPC), an important organic chemical, can be synthesized from aniline, CO2 and methanol. Catalyst Cu-Fe/ZrO2-SiO2 was first prepared and its catalytic performance for MPC synthesis was evaluated. Then the influence of solvent on the reaction path of MPC synthesis was investigated. It is found that the reaction intermediate is different with acetonitrile or methanol as a solvent. With acetonitrile as a solvent, the synthesis of MPC follows the reaction path with diphenyl urea as the intermediate, while with methanol as a solvent the reaction occurs via the reaction path with dimethyl carbonate as the intermediate. The catalytic mecha-nism of cooperative catalysis comprising metal sites, Lewis acid sites and Lewis base sites is proposed according to different reaction intermediates.

  10. 119Sn MAS NMR Study of Probe Molecules Interaction with Sn-BEA: The Origin of Penta- and Hexacoordinated Tin Formation

    DEFF Research Database (Denmark)

    Yakimov, Alexander V.; G. Kolyagin, Yury; Tolborg, Søren


    119Sn CPMG MAS NMR was applied to study the adsorption of acetonitrile, methanol, isopropanol, isobutanol and water over Sn-BEA enriched with 119Sn isotope. Two signals observed at ca. -422 and -443 ppm over dehydrated samples were attributed to tetracoordinated framework tin sites with strong...... and weak Lewis acidity, respectively. The adsorption of acetonitrile and methanol resulted in observation of pentacoordinated tin species, due to the formation of 1:1 adsorption complexes over both Sn-sites. Water adsorption led first to formation of pentacoordinated tin species, which were further...... converted into hexacoordinated species at longer reaction times. The latter transformation was found to be kinetically limited and was attributed to chemical interaction of tin sites with water, such as hydrolysis of Si-O-Sn bonds. The adsorption of isopropanol and isobutanol was accompanied...

  11. fac-Acetonitriletricarbonyl(dimethylcarbamodithioato-κ2S,S′rhenium(I: crystal structure and Hirshfeld surface analysis

    Directory of Open Access Journals (Sweden)

    Sang Loon Tan


    Full Text Available The title compound, [Re(C3H6NS2(C2H3N(CO3], features an octahedrally coordinated ReI atom within a C3NS2 donor set defined by three carbonyl ligands in a facial arrangement, an acetonitrile N atom and two S atoms derived from a symmetrically coordinating dithiocarbamate ligand. In the crystal, dithiocarbamate-methyl-H...O(carbonyl interactions lead to supramolecular chains along [36-1]; both dithiocarbamate S atoms participate in intramolecular methyl-H...S interactions. Further but weaker acetonitrile-C—H...O(carbonyl interactions assemble molecules in the ab plane. The nature of the supramolecular assembly was also probed by a Hirshfeld surface analysis. Despite their weak nature, the C—H...O contacts are predominant on the Hirshfeld surface and, indeed, on those of related [Re(CO3(C3H6NS2L] structures.

  12. Flexibility transition and guest-driven reconstruction in a ferroelastic metal-organic framework†Electronic supplementary information (ESI) available: Atomic coordinates and lattice parameter data. CCDC 1016797. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4ce01572jClick here for additional data file. (United States)

    Hunt, Sarah J; Cliffe, Matthew J; Hill, Joshua A; Cairns, Andrew B; Funnell, Nicholas P; Goodwin, Andrew L


    The metal-organic framework copper(i) tricyanomethanide, Cu(tcm), undergoes a ferroelastic transition on cooling below Tf = 240 K. Thermal expansion measurements reveal an order-of-magnitude variation in framework flexibility across Tf. The low-temperature phase α-Cu(tcm) exhibits colossal positive and negative thermal expansion that is the strongest ever reported for a framework material. On exposure to acetonitrile, Cu(tcm) undergoes a reconstructive solid-phase transition to acetonitrilocopper(i) tricyanomethanide. This transition can be reversed by heating under vacuum. Infrared spectroscopy measurements are sensitive to the phase change, suggesting that Cu(tcm) may find application in solid-phase acetonitrile sensing.

  13. Fate of 2,4,6-Trinitrotoluene in a Simulated Compost System (United States)


    of agricultural and other wastes. J. K. R. Gasser, ed., Elsevier Applied Science Publishers, London, 42-55. Stevenson , F. J. (1989). Humus chemistry...vii 1 Introduction Background and Rationale Composting is generally defined as a microbial process for conversion of organic wastes into humus under...acetonitrile. Organic matter fractionation: Experiment IV. The organic matter frac- tionation procedure was adapted from Stevenson (1989) (Figure 3

  14. Poly(N-vinylimidazole/ethylene glycol dimethacrylate) for the purification and isolation of phenolic acids

    Energy Technology Data Exchange (ETDEWEB)

    Schemeth, Dieter; Noël, Jean-Christophe [Institute of Analytical Chemistry and Radiochemistry, Leopold-Franzens University of Innsbruck, CCB—Center of Chemistry and Biomedicine, Innrain 80-82, 6020 Innsbruck (Austria); Jakschitz, Thomas [Austrian Drug Screening Institute, Innrain 66a, 6020 Innsbruck (Austria); Rainer, Matthias, E-mail: [Institute of Analytical Chemistry and Radiochemistry, Leopold-Franzens University of Innsbruck, CCB—Center of Chemistry and Biomedicine, Innrain 80-82, 6020 Innsbruck (Austria); Tessadri, Richard [Institute of Mineralogy and Petrography, Leopold-Franzens University of Innsbruck, Innrain 52, 6020 Innsbruck (Austria); Huck, Christian W. [Institute of Analytical Chemistry and Radiochemistry, Leopold-Franzens University of Innsbruck, CCB—Center of Chemistry and Biomedicine, Innrain 80-82, 6020 Innsbruck (Austria); Bonn, Günther K. [Institute of Analytical Chemistry and Radiochemistry, Leopold-Franzens University of Innsbruck, CCB—Center of Chemistry and Biomedicine, Innrain 80-82, 6020 Innsbruck (Austria); Austrian Drug Screening Institute, Innrain 66a, 6020 Innsbruck (Austria)


    Highlights: • Free-radical polymerization of protonable vinylimidazole with EGMDA. • Polymer-optimization by maximum loading capacity of phenolic acids. • Performs better than SiO{sub 2} and Al{sub 2}O{sub 3} in normal phase mode using acetonitrile. • Performs equal or even better in anion-exchange mode compared to Oasis-MAX. • Efficient purification of phenolic compounds from crude extract. - Abstract: In this study we report the novel polymeric resin poly(N-vinyl imidazole/ethylene glycol dimethacrylate) for the purification and isolation of phenolic acids. The monomer to crosslinker ratio and the porogen composition were optimized for isolating phenolic acids diluted in acetonitrile at normal phase chromatography conditions, first. Acetonitrile serves as polar, aprotic solvent, dissolving phenolic acids but not interrupting interactions with the stationary phase due to the approved Hansen solubility parameters. The optimized resin demonstrated high loading capacities and adsorption abilities particularly for phenolic acids in both, acetonitrile and aqueous solutions. The adsorption behavior of aqueous standards can be attributed to ion exchange effects due to electrostatic interactions between protonated imidazole residues and deprotonated phenolic acids. Furthermore, adsorption experiments and subsequent curve fittings provide information of maximum loading capacities of single standards according to the Langmuir adsorption model. Recovery studies of the optimized polymer in the normal-phase and ion-exchange mode illustrate the powerful isolation properties for phenolic acids and are comparable or even better than typical, commercially available solid phase extraction materials. In order to prove the applicability, a highly complex extract of rosemary leaves was purified by poly(N-vinyl imidazole/ethylene glycol dimethacrylate) and the isolated compounds were identified using UHPLC–qTOF-MS.

  15. Hydrogenation of biomass-derived substrates (United States)

    Gordon, John C.; Waidmann, Christopher R.


    The .alpha.,.beta.-unsaturated ketone moiety of a substrate representative of non-food based biomass was hydrogenated to the corresponding saturated alcohol moiety using a composition including (1) a copper salt; (2) a phosphine; (3) a polar aprotic solvent such as acetonitrile, and (4) a compound suitable for providing hydrogen for the hydrogenation, such as a suitable silane material or a suitable siloxane material.

  16. Effect of hydrostatic pressure, temperature, and solvent on the rate of the Diels-Alder reaction between 9,10-anthracenedimethanol and maleic anhydride (United States)

    Kiselev, V. D.; Kornilov, D. A.; Anikin, O. V.; Latypova, L. I.; Konovalov, A. I.


    The rate of the reaction between 9,10-anthracenedimethanol and maleic anhydride in 1,4-dioxane, acetonitrile, trichloromethane, and toluene is studied at 25, 35, 45°C in the pressure range of 1-1772 bar. The rate constants, enthalpies, entropies and activation volumes are determined. It is shown that the rate of reaction with 9,10-anthracenedimethanol is approximately one order of magnitude higher than with 9-anthracenemethanol.

  17. Synthesis and reactivity of a conveniently prepared two-coordinate bis(amido) nickel(II) complex. (United States)

    Lipschutz, Michael I; Tilley, T Don


    A strictly two-coordinate nickel(II) bis(amido) complex has been prepared and its reactivity towards a variety of small molecules is described. Ni[N(SiMe(3))(DIPP)](2) reacts with DMAP and acetonitrile to form T-shaped three-coordinate complexes, and preliminary results show that Ni[N(SiMe(3))(DIPP)](2) is a catalyst for the hydrosilation of olefins with secondary silanes at ambient temperature.

  18. Copper(II tetrafluoroborate as mild and versatile catalyst for the

    Directory of Open Access Journals (Sweden)

    Jihillu. S. Yadav


    Full Text Available A variety of -acetamido ketones and ketoesters are readily prepared in high yields under extremelymild conditions via a three component coupling of aromatic aldehydes, enolizable ketones or -ketoesters andnitriles in the presence of 10 mol% of copper(II tetrafluoroborate and a stoichiometric amount of acetylchloride. A solution of 10 mol% of Cu(BF42 in acetonitrile provides a convenient reaction medium to carry out athree component reaction under mild conditions

  19. Development and Validation of a Precise, Single HPLC Method for the Determination of Tolperisone Impurities in API and Pharmaceutical Dosage Forms


    RAJU, Thummala; Seshadri, Raja; Arutla, Srinivas; MOHAN, Tharlapu; RAO, Ivaturi; NITTALA, Someswara


    A novel, sensitive, stability-indicating HPLC method has been developed for the quantitative estimation of Tolperisone-related impurities in both bulk drugs and pharmaceutical dosage forms. Effective chromatographic separation was achieved on a C18 stationary phase with a simple mobile phase combination delivered in a simple gradient programme, and quantitation was by ultraviolet detection at 254 nm. The mobile phase consisted of a buffer and acetonitrile delivered at a flow rate 1.0 ml/min. ...

  20. Sample preparation and biopharmaceutical analysis


    Farrelly, Gillian


    In chapter 1, an overview is given of sample preparation methods and analytical techniques in use today. Each one is discussed, and relevant examples are given. In chapter 2, the development of a method for the HPLC analysis of taurine in human plasma using acetonitrile precipitation and pre-column derivatisation with fluorescamine is presented. This procedure was found to be faster and easier to use than previous taurine assays. In chapter 3, the evaluation of novel aspirin derivativ...

  1. Diversity in electrochemical oxidation of dihydroxybenzenes in the presence of 1-methylindole

    Indian Academy of Sciences (India)

    Davood Nematollahi; Vahid Hedayatfar


    Electrochemical oxidation of some catechol derivatives (1a-e) have been studied in water/acetonitrile solution containing 1-methylindole (3) as a nucleophile, using cyclic voltammetry and controlledpotential coulometry. An interesting diversity in the mechanisms has been observed in electrochemical oxidation of catechol derivatives (1a-e) in the presence of 3. In this work, we have proposed reaction schemes , and for oxidation of 1a-e in the presence of 3.

  2. Impact of mobile phase composition on the performance of porous polymeric monoliths in the elution of small molecules. (United States)

    Causon, Tim J; Hilder, Emily F; Nischang, Ivo


    The influence of mobile phase solvent composition and consequently retention factor on the chromatographic performance for a set of small molecules was studied using a commercially available poly(styrene-co-divinyl benzene) analytical scale porous polymeric monolithic column as an example. Chromatographic elution performance was studied across retention factors from close to 0 up to 100 realized for a set of structurally similar small molecules in a binary reversed-phase solvent environment of acetonitrile and water. By altering the mobile phase composition from volume fractions of acetonitrile of just 10% (v/v) to only acetonitrile it was systematically shown that gel porosity of the monolithic column plays a dominant role in modulating mass transport and the associated chromatographic efficiency in a consistent manner. Up to a sixfold difference in plate height was recorded for the most strongly retained hydrophobic solute (ethylbenzene) at a constant, low flow velocity simply by varying the amount of acetonitrile in the mobile phase. Plate height curves recorded for the set of solutes that comprise benzene, toluene, ethylbenzene as well as phenol and benzyl alcohol further demonstrate the importance of functional group content of the solute and the modulated porous gel structure on mass transport. These results highlight some important practical considerations for characterizing the chromatographic properties of any polymeric monolithic column. First, it is imperative that any chromatographic performance characterization using plate height data explicitly considers the influence of mobile phase composition, retention factor, molecular size and functional groups of the probe solute. Second, as the physicochemical conditions of the material are directly reflected in the gel porosity, a range of different mobile phase compositions, retention factors and probe-specific effects must be investigated to yield a fair appraisal of the chromatographic performance.

  3. A new solvate of afatinib, a specific inhibitor of the ErbB family of tyrosine kinases

    Directory of Open Access Journals (Sweden)

    Matthias Zeller


    Full Text Available Afatinib (systematic name: N-{4-(3-chloro-4-fluoroanilino-7-[(tetrahydrofuran-3-yloxy]quinazolin-6-yl}-4-(dimethylaminobut-2-enamide, is a specific inhibitor of the ErbB family of tyrosine kinases. The free base form crystallizes from acetonitrile as a mixed water–acetonitrile solvent, C24H25ClFN5O3·0.25C2H3N·2H2O. It crystallizes with two independent molecules (A and B in the asymmetric unit of the chiral space group P4212, but exhibits close to perfect pseudo-inversion symmetry, emulating P4/ncc that relates the two molecules to each other. Exact inversion symmetry is however broken by swapping of oxygen and CH2 moieties of the outer tetrahydrofuranyl substituents of the two independent molecules. This can, in turn, be traced back to C—H...N and C—H...O interactions of the acetonitrile solvent molecules with the tetrahydrofuran oxygen and CH2 units. In the crystal, neighboring molecules are connected via N—H...O hydrogen bonds between the secondary amine and the amide keto O atom. Additional hydrogen bonds are formed through the water solvent molecules, which are engaged in O—H...O and O—H...N hydrogen bonds connecting to the dimethylamino N atom, the amide keto O atom, and one of the quinazoline N atoms of a neighboring molecule, leading to an intricate three-dimensional hydrogen-bonded superstructure. There are two types of channels stretching along the direction of the c axis; one along the fourfold rotational axis, occupied by acetonitrile solvent molecules situated on that axis, and parallel channels which are not occupied by any solvent.

  4. Ruthenium(III Chloride Catalyzed Acylation of Alcohols, Phenols, and Thiols in Room Temperature Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Mingzhong Cai


    Full Text Available Ruthenium(III chloride-catalyzed acylation of a variety of alcohols, phenols, and thiols was achieved in high yields under mild conditions (room temperature in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]. The ionic liquid and ruthenium catalyst can be recycled at least 10 times. Our system not only solves the basic problem of ruthenium catalyst reuse, but also avoids the use of volatile acetonitrile as solvent.

  5. A Peptide Amphiphile Organogelator of Polar Organic Solvents (United States)

    Rouse, Charlotte K.; Martin, Adam D.; Easton, Christopher J.; Thordarson, Pall


    A peptide amphiphile is reported, that gelates a range of polar organic solvents including acetonitrile/water, N,N-dimethylformamide and acetone, in a process dictated by β-sheet interactions and facilitated by the presence of an alkyl chain. Similarities with previously reported peptide amphiphile hydrogelators indicate analogous underlying mechanisms of gelation and structure-property relationships, suggesting that peptide amphiphile organogel design may be predictably based on hydrogel precedents. PMID:28255169

  6. Recommended methods for purification of solvents and tests for impurities

    CERN Document Server

    Coetzee, J F


    Recommended Methods for Purification of Solvents and Tests for Impurities is a compilation of recommended procedures for purification of solvents and tests for solvent impurities. Ten solvents are covered: acetonitrile, sulfolane, propylene carbonate, dimethyl sulfoxide, dimethylformamide, hexamethylphosphoramide, pyridine, ethylenediamine, N-methylacetamide, and N-methylpropionamide. This book is comprised of 12 chapters and opens with an introduction to general aspects of impurity effects. The rationale for the selection of solvent is explained, and the relative reactivities of solutes in di

  7. Enantiomeric Separation of Antidepressant Trimipramine by Capillary Electrophoresis Combined with Electrochemiluminescence Detection in Aqueous-organic Media

    Institute of Scientific and Technical Information of China (English)

    YU Cai-xia; YUAN Bai-qing; YOU Tian-yan


    The antidepressant trimipramine(Tri) enantiomers were successfully separated by capillary electrophoresis(CE) coupled with electrochemiluminescence(ECL) detection in aqueous-organic media. A dual cyclodextrin(CD)system combining β-CD and hydroxypropyl-β-cyclodextrin(HP-β-CD) was used as chiral selector. Acetonitrile(ACN)was added to the running buffer to improve the separation efficiency, detection sensitivity and repeatability. The method was also successfully applied to the chiral separation of Tri in spiked human urine sample.

  8. Undistorted Cyclic Voltammograms at Scan Rates up to 2.5 MV·s-1 through Positive Feedback Compensation of Ohmic Drop

    Institute of Scientific and Technical Information of China (English)

    GUO Zhi-Yong郭智勇; LIN Xiang-Qin林祥钦; DENG Zhao-Xiang邓兆祥


    A circuit based on the current feedback operational amplifier was constructed to accomplish on-line ohmic drop compensation in ultrafast cyclic voltammetry. Firstly, its characteristics were confirmed experimentally on dummy cells. Then the reduction of anthracene in acetonitrile, a classical test example with very fast electron-tratnsfer kinetics, was examined to prove them too. The results showed that this circuit could afford excellent ohmic drop if 5% error is tolerated.

  9. Determination of stability constants of 5-(2-hydroxybenzylidene)-2-thioxodihydropyrimidine-4,6(1H,5H)-dione with copper(II) and mercury(II) ions


    Bahram,Morteza; Pesyan, Nader Noroozi


    In this work, a hard model chemometric method was used to determine the stability constants of copper(II) and mercury(II) complexes with the newly synthesized ligand 5-(2-hydroxybenzylidene)- 2-thioxodihydropyrimidine-4,6(1H,5H)-dione in acetonitrile by UV-Vis spectrophotometry. The ligand forms stable complexes with both metal cations. The protonation constants of the ligand were also measured in an ethanol-water (1:1) mixture.

  10. Development of practical HPLC methods for the separation and determination of eggplant steroidal glycoalkaloids and their aglycones


    Eanes, Ritchie C.; Tek, Neslihan; Kırsoy, Öyküm; FRARY, Anne; Doğanlar, Sami; Almeida, Adelia E.


    A practical set of HPLC methods was developed for the separation and determination of the eggplant steroidal glycoalkaloids, solanine, chaconine, solasonine, solamargine, and their aglycones, solasodine and solanidine. A gradient method was initially developed, but proved to be neither robust nor practical. Three separate isocratic methods using acetonitrile and ammonium dihydrogen phosphate were developed and shown to be more repeatable, less subject to fluctuations in mobile phase compositi...

  11. A new approach for the determination of immunosuppressive drugs using HPLC-MS/MS and Cs+ adducts


    Reinauer, Hans; Wood, William Graham; Akerboom, Theodorus; Kaiser, Patricia


    In this study a new principle of measurement in LC-MS/MS (liquid chromatography mass spectrometry) for determination of the immunosuppressive drugs sirolimus, everolimus, tacrolimus, and cyclosporin A has been introduced by using the Cs+ ion as the product ion in the multiple reaction monitoring mode (MRM). Separation of the immunosuppressive agents was achieved using a phenyl-hexyl-RP column together with a ternary gradient elution profile, consisting of water, methanol and acetonitrile comb...

  12. Solid-supported sulfonic acid-containing catalysts efficiently promoted one-pot multi-component synthesis of -acetamido carbonyl compounds

    Indian Academy of Sciences (India)

    Mohammad Ali Zolfigol; Ardeshir Khazaei; Abdolkarim Zare; Mohammad Mokhlesi; Tahereh Hekmat-Zadeh; Alireza Hasaninejad; Fatemeh Derakhshan-Panah; Ahmad Reza Moosavi-Zare; Hassan Keypour; Ahmad Ali Dehghani-Firouzabadid; Maria Merajoddin


    Silica-functionalized sulfonic acid (SFSA) and sulfuric acid-modified polyethylene glycol-6000 (PEG-OSO3H) efficiently catalysed one-pot multi-component condensation of enolizable ketones or alkyl acetoacetates with arylaldehydes, acetonitrile and acetyl chloride to afford the corresponding -acetamido ketone or ester derivatives in high to excellent yields and in relatively short reaction times. Moreover, in this work, some novel -acetamido carbonyl compounds (i.e., one complex structure) are synthesized.

  13. The solvatochromic, spectral, and geometrical properties of nifenazone: A DFT/TD-DFT and experimental study


    Bani-Yaseen, Abdulilah Dawoud; Al-Balawi, Mona


    The solvatochromic, spectral, and geometrical properties of nifenazone (NIF), a pyrazole-nicotinamide drug, were experimentally and computationally investigated in several neat solvents and in hydro-organic binary systems such as water-acetonitrile and water-dioxane systems. The bathochromic spectral shift observed in NIF absorption spectra when reducing the polarity of the solvent was correlated with the orientation polarizability (?f). Unlike aprotic solvents, a satisfactory correlation bet...

  14. Extraction, Separation, and Identification of Phenolic Compounds in Virgin Olive Oil by HPLC-DAD and HPLC-MS


    Maria Tasioula-Margari; Eleftheria Tsabolatidou


    The aim of this study was to evaluate the recovery of individual phenolic compounds extracted from virgin olive oil (VOO), from different Greek olive varieties. Sufficient recoveries (90%) of all individual phenolic compounds were obtained using methanol as an extraction solvent, acetonitrile for residue solubilization, and two washing steps with hexane. Moreover, in order to elucidate structural characteristics of phenolic compounds in VOO, high performance liquid chromatography with a diode...

  15. One Pot Reduction of Imines Generated in-situ from Aldehydes and Amines by the NaBH4-InCl3 System

    Institute of Scientific and Technical Information of China (English)

    RAVI Varala; RAMU Enugala; VIJAY KUMAR Ponnamaneni; SRINIVAS RAO Adapa


    A combination of sodium borohydride and a catalytic amount of indium(Ⅲ) chloride in acetonitrile reduces imines formed in-situ from aldehydes and amines to the corresponding functionalised secondary and tertiary amines in moderate to good yields. Noteworthy is that highly chemoselective reactions were achieved in the presence of other functional groups such as halogens, carbon-carbon double bonds and hydroxyl groups.

  16. Oxazine-thione-based Colorimetric Fluorescent OFF-ON Probes for Hg2+ Recognition%Oxazine-thione-based Colorimetric Fluorescent OFF-ON Probes for Hg2+ Recognition

    Institute of Scientific and Technical Information of China (English)

    张欠欠; 孙如; 葛健锋; 徐庆锋; 李娜君; 路建美


    Two colorimetric probes based on oxazine-thione la and lb for the detection of Hg2+ were designed and synthesized. The probe la exhibits about a 70-fold enhancement in fluorescence and a color change alter the addition of Hg2+ in acetonitrile/wate solvent, la was also highly selective to Hg2+ over other metal ions. Furthermore, DFT/TDDFT calculations were taken to explain the OFF-ON emission response.

  17. Sheath liquid effects in capillary high-performance liquid chromatography-electrospray mass spectrometry of oligonucleotides. (United States)

    Huber, C G; Krajete, A


    Fused-silica capillary columns of 200 microm inner diameter were packed with micropellicular, octadecylated, 2.3 microm poly(styrene-divinylbenzene) particles and applied to the separation of oligonucleotides by ion-pair reversed-phase high-performance liquid chromatography. Oligonucleotides were eluted at 50 degrees C with gradients of 3-13% acetonitrile in 50 mM triethylammonium bicarbonate. Addition of sheath liquid to the column effluent allowed the detection of oligonucleotides by electrospray ionization mass spectrometry using full-scan data acquisition with a detectability comparable to that obtained with UV detection. The signal-to-noise ratios with different sheath liquids increased in the order isopropanolacetonitrile. The incorporation of volatile acids or bases such as triethylamine or hexafluoroisopropanol into the sheath liquid was found to influence the charge state distribution of oligonucleotides longer than 20 nucleotide units whereas no significant effect was observed with shorter oligonucleotides. Organic acids and bases in the sheath liquid generally deteriorated the signal-to-noise ratios in the chromatograms and mass spectra mainly because of increased background noise. Only a few charge states were observed in the mass spectra of oligonucleotides because of charge state reduction due to the presence of carbonic acid in the eluent. With triethylammonium hydrogencarbonate as chromatographic eluent and acetonitrile as sheath liquid, very few cation adducts of oligonucleotides were observed in the mass spectra. However, the presence of small amounts of monopotassium adducts enabled the calculation of the charge state of multiply charged ions. With acetonitrile as sheath liquid, 710 amol of a 16-mer oligonucleotide were detected using selected ion monitoring data acquisition with a signal-to-noise ratio of 3:1. Finally, capillary ion-pair reversed-phase high-performance liquid chromatography-electrospray ionization mass spectrometry was

  18. 3,5-Bis(4-dodecylthiophen-2-yl-4H-1,2,6-thiadiazin-4-one

    Directory of Open Access Journals (Sweden)

    Panayiotis A. Koutentis


    Full Text Available 3,5-Dichloro-4H-1,2,6-thiadiazin-4-one 1 reacts with (4-dodecylthiophen-2-yltrimethylstannane 4 (2.2 equiv. and Pd(Ph3P2Cl2 (5 mol% in acetonitrile at ca. 82 °C to give 3,5-bis(4-dodecylthiophen-2-yl-4H-1,2,6-thiadiazin-4-one 5 in 93% yield.

  19. Silylaryl triflates in the formation of arynes with application in the preparation of N,N-diarylamino acid derivatives

    Directory of Open Access Journals (Sweden)

    Danilo Y. Albuquerque


    Full Text Available Through this work we are developing our research involving the formation of arynes from 2-(trimethylsilylaryl triflates, under relatively mild reaction conditions. Thus, esters of amino acids are being subjected to the reaction with 2-(trimethylsilylaryl triflates, using cesium fluoride in acetonitrile at 80oC for 24 h, resulting in the formation of N,N-diarylamino acid derivatives, important chiral intermediates in the construction of peptides and drugs.

  20. [Comparison of refractometric and ultraviolet detection methods in lactulose assay by high performance liquid chromatography]. (United States)

    Vaccher, C; Berthelot, P; Flouquet, N; Debaert, M


    Dosage of lactulose and determination of related sugars (lactose, fructose, galactose, épilactose) were undertaken by high performance liquid chromatography (HPLC). The present note described two modes of detection used simultaneously and compared: refractive index detector (RI) and multiwavelength ultraviolet detector (UV). HPLC is performed with an aminopropylsylil phase as stationary phase and an isocratic mobile phase containing acetonitrile and aqueous sodium phosphate. The results are outlined and discussed.

  1. An improved extraction method of rapeseed oil sample preparation for the subsequent determination in it of azole class fungicides by gas chromatography

    Directory of Open Access Journals (Sweden)

    Mikhail F. Zayats


    Full Text Available The distribution of 19 azole class pesticides in hexane/aqueous–organic mixtures systems and rapeseed oil (or oil solution in hexane/organic solvents has been studied at 20 ± 1 °C. The distribution constants (P and coefficients (D between hydrocarbon and polar phase are calculated. It is found that all the studied pesticides are hydrophobic, i.e., in hexane–water system logP ≫ 0. Replacement of water by organic solvents results in sharp logP falling, and their values become negative. It is revealed that solutions of strong inorganic acids in anhydrous acetonitrile extract azole class pesticides from hexane and vegetable oils most fully and selectively. In particular, the acidification of acetonitrile causes a drop of D values in 50–2000 times for the majority of the studied pesticides. This phenomenon was used for the development of the improved technique for the quantitative analysis of a widely used azole class pesticides, which can be presented at trace levels in rapeseed oil. The proposed methodology is based on dissociation extraction (DE of azoles using perchloric acid in anhydrous acetonitrile, with following clean-up of acetonitrile extract from organic impurities by hexane and aqueous solution of dipotassium hydrogen orthophosphate, and final GC–ECD (gas chromatography with electron capture detection determination of azole fungicides. The values of obtained recoveries were between 85% and 115% with RSD values below 10%. The obtained limits of quantitation, ranged from 3.0 to 300 μg kg−1, are below the maximum residue levels (MRLs set by the European Union for the majority of pesticides. The developed method was successfully applied to different rapeseed oil samples.

  2. Studies on Hydroiodination and Deconjugation of 5-Aryloxy-(thiophenyl)-3-pentyn-2-one

    Institute of Scientific and Technical Information of China (English)

    LIU,Li-Jun(刘利军); LUO,Fen-Tair(罗芬台)


    One-pot hydroiodination and deconjugation of 5-aryloxy (or thiophenyl)-3-pentyn-2-one with a reagent system of sodium iodide/trimethylsilyl chloride/water in acetonitrile at 25 ℃ have been described. The plausible mechanism was discussed. The reaction provided a simple and useful method for the preparation of ( Z )-β-substituted β, γ-enones and ( Z )-β-substituted α, β-unsaturated ketones.

  3. Wet-chemical systems and methods for producing black silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Yost, Vernon; Yuan, Hao-Chih; Page, Matthew


    A wet-chemical method of producing a black silicon substrate. The method comprising soaking single crystalline silicon wafers in a predetermined volume of a diluted inorganic compound solution. The substrate is combined with an etchant solution that forms a uniform noble metal nanoparticle induced Black Etch of the silicon wafer, resulting in a nanoparticle that is kinetically stabilized. The method comprising combining with an etchant solution having equal volumes acetonitrile/acetic acid:hydrofluoric acid:hydrogen peroxide.

  4. Voltammetric Behaviour of Sulfamethoxazole on Electropolymerized-Molecularly Imprinted Overoxidized Polypyrrole

    Directory of Open Access Journals (Sweden)

    Yücel Sahin


    Full Text Available In this work, preparation of a molecularly imprinted polymer (MIP film and its recognition properties for sulfamethoxazolewere investigated. The overoxidized polypyrrole (OPPy film was prepared by the cyclic voltammetric deposition of pyrrole (Py in the presence of supporting electrolyte (tetrabutylammonium perchlorate-TBAP with and without a template molecule (sulfamethoxazole on a pencil graphite electrode (PGE. The voltammetric behaviour of sulfamethoxazole on imprinted and non-imprinted (NIP films was investigated by differential pulse voltammetry (DPV in Britton-Robinson (BR buffer solutions prepared in different ratio of acetonitrile-water binary mixture, between the pH 1.5 and 7.0. The effect of the acetonitrile-water ratio and pH, monomer and template concentrations, electropolymerization cycles on the performance of the MIP electrode was investigated and optimized. The MIP electrode exhibited the best reproducibility and highest sensitivity. The results showed that changing acetonitrile-water ratio and pH of BR buffer solution changes the oxidation peak current values. The highest anodic signal of sulfamethoxazole was obtained in BR buffer solution prepared in 50% (v/v acetonitrile-water at pH 2.5. The calibration curve for sulfamethoxazole at MIP electrode has linear region for a concentration range of 25.10-3 to 0.75 mM (R2=0.9993. The detection limit of sulfamethoxazole was found as 3.59.10-4 mM (S/N=3. The same method was also applied to determination of sulfamethoxazole in commercial pharmaceutical samples. Method precision (RSD87% were satisfactory. The proposed method is simple and quick. The polypyrrole (PPy electrodes have low response time, good mechanical stability and are disposable simple to construct.

  5. Rescue of TET2 Haploinsufficiency in Myelodysplastic Syndrome Patients Using Turbo Cosubstrate (United States)


    based assay to be most reliable. 1c. Synthesize , purify and characterize a library of 2OG analogs using the scheme reported in the application...acetonitrile containing 0.1% acetic acid). Initially, we used phosphate buffer in solvents, which resulted in the desired separation of nucleosides. However...the residual phosphate ions suppressed the ionization of nucleosides during both the later LCMS and MALDI-TOF experiments. To overcome this

  6. Photochemical Studies on 5-Methylbicyclo[1.1.1]pentane Derivatives: p-Orbital Overlap Controlled Enantioselectivity

    Institute of Scientific and Technical Information of China (English)

    马满玲; 杨超; 李冰; 邵玉田; 赵国磊; 夏吾炯


    The first example of the p-orbital overlap controlled enantioselectivity of Norrish type II photocyclization reaction was described. Irradiation of 5-methyl bicyclo[l. 1.1 ]pentanyl ketone with UV in the solid state as well as in the acetonitrile solution afforded the Norrish/Yang photocyclization compound as the sole product. Solid-state asymmetric photochemical studies using ionic chiral auxiliary technique led to the enantioselectivity as high as 60%. The results were rationalized by Xray single crystal structure.

  7. Lignin Peroxidase Oxidation of Aromatic Compounds in Systems Containing Organic Solvents


    Vazquez-Duhalt, Rafael; Westlake, Donald W. S.; Fedorak, Phillip M.


    Lignin peroxidase from Phanerochaete chrysosporium was used to study the oxidation of aromatic compounds, including polycyclic aromatic hydrocarbons and heterocyclic compounds, that are models of moieties of asphaltene molecules. The oxidations were done in systems containing water-miscible organic solvents, including methanol, isopropanol, N, N-dimethylformamide, acetonitrile, and tetrahydrofuran. Of the 20 aromatic compounds tested, 9 were oxidized by lignin peroxidase in the presence of hy...

  8. Electrochemical Synthesis and Structural Characterization of a Novel Mixed-valence Copper (I)-copper (II) Complex: {[Bis(ethylenediamine) Copper (II)] Bis[diiodocuprate (I)]}


    Mahboobeh Dashti Ardakani; Majid M. Heravi; Saeed Dehghanpour; Lida Fotouhi


    A novel, mixed-valent copper(I)-copper(II) complex, {[bis(ethylene-diamine)copper(II)] bis[diiodocuprate(I)]} (1), has been prepared by electrochemicaldissolution of a sacrificial copper anode in a solution of ethylenediamine (en), I2 andtetraethylammoniumperchlorate (TEAP) as supporting electrolyte in acetonitrile (AcN)and characterized by single-crystal X-ray structure determination. The crystal structure ofthe complex 1 shows that it consists of a CuI2 polymer formed from I- ligands bridgi...

  9. Preconcentration and electroanalysis of copper at glassy carbon electrode modified with poly(2-aminothiazole)


    Çiftçi, Hakan; Testereci, Hasan Nur; Öktem, Zeki


    Conducting poly(2-aminothiazole), PAT, was synthesized in acetonitrile with tetrabutylammonium tetrafluoroborate, TBAFB, as supporting electrolyte via constant potential electrolysis, CPE. Glassy carbon, GC, electrode was modified by immersing the electrode in a DMSO solution of PAT. Preconcentration of copper on polymer matrix was carried out at -0.7 V. The effects of preconcentration time and pH and Cu(II) concentration of the preconcentration solution on the stripping peak current of coppe...

  10. Reaction kinetics of resveratrol with tert-butoxyl radicals (United States)

    Džeba, Iva; Pedzinski, Tomasz; Mihaljević, Branka


    The rate constant for the reaction of t-butoxyl radicals with resveratrol was studied under pseudo-first order conditions. The rate constant was determined by measuring the phenoxyl radical formation rate at 390 nm as function of resveratrol concentration in acetonitrile. The rate constant was determined to be 6.5×108 M-1s-1. This high value indicates the high reactivity consistent with the strong antioxidant activity of resveratrol.

  11. Simultaneous Determination of Four Active Ingredients in Sargentodoxa cuneata by HPLC Coupled with Evaporative Light Scattering Detection


    Di-Hua Li; Yuan-Shan Lv; Jun-Hong Liu; Lei Yang; Yan Wang; Shu-Kun Zhang; Yu-Zhen Zhuo


    A HPLC coupled with evaporative light scattering detection method had been developed for the simultaneous determination of 3,4-dihydroxyphenylethyl alcohol glycoside, salidroside, chlorogenic acid, and liriodendrin in the stem of Sargentodoxa cuneata. With a C18 column, the analysis was performed using acetonitrile and 0.2% formic acid aqueous solution as mobile phase in gradient program at a flow rate of 0.9 mL/min. The optimum drift tube temperature of evaporative light scattering detection...

  12. Stromal Mesenchyme Cell Genes in Prostate Cancer Development: Epigenetic Markers for Cancer and Potential Targets for Therapy (United States)


    basement membrane and the extracellular matrix. Prostate development is also under hormonal control and the influence of androgen is primarily mediated...cleaved peptides were removed, and the resin was washed three times successively each in the following solutions: 1.5 M NaCl, 80% acetonitrile ( ACN ), 100...England Biolabs, Beverly, MA) at 37°C overnight. Released peptides were dried and resuspended in 50% ACN , 0.1 % formic acid for MS analysis. Four

  13. Three hydroxy aurone compounds as chemosensors for cyanide anions. (United States)

    Chen, Huihui; Sun, Yunhui; Zhou, Chuanjian; Cao, Duxia; Liu, Zhiqiang; Ma, Lin


    Three new 4-hydroxy aurone compounds 1-3 with dimethylamino (1), bromine (2) and cyano (3) as terminal group have been synthesized. Their photophysical properties as well as recognition properties for cyanide anions in acetonitrile and aqueous solution have also been examined. These compounds exhibit remarkable response to cyanide anions with obvious color and fluorescence change owing to hydrogen bonding reaction between cyanide anions and the O-H moiety of the sensors, which allows naked eye detection of cyanide anions.



    Bhavin Chapla; Gunjan Amin; Ashutosh Pandya; Jagdish Kakadiya; Nehal Shah


    The present manuscript describes new, simple, accurate, and precise high performance thin layer chromatography method for the simultaneous determination of Vardenafil and Dapoxetine in combined tablet dosage form. Chromatographic separation of the drugs was performed on aluminium plates pre coated with silica gel 60 F254 as the stationary phase and the solvent system consisted of Chloroform: Methanol: Acetonitrile: Formic acid (4: 0.8: 4: 1 v/v/v/v). Densitometric evaluation of the separated ...

  15. Determination of taxol content in plant and cell cultures of Taxus improving HPLC method%改进的HPLC法测定红豆杉植物和细胞培养物中紫杉醇的含量

    Institute of Scientific and Technical Information of China (English)



    Taxol content from the branches and leaves of Taxus chinensis var. Mairei (Lemeé et Lévl.) Cheng et L. K. Fu and its cell cultures was analyzed by using Nova-Pak C18 column and improving the proportion of mobile phase (methanol/ acetonitrile/ water) and modifing column temperature at a wavelength of 227 nm. The improved HPLC method is celerity, nicety and delicacy. The lowest detectable quantity of taxol could reach 0.005 μg.

  16. 31p NMR and ESI-MS Studies on Some Intermediates of the Peptide Coupling Reagents Triphenyl-chlorophosphoranes

    Institute of Scientific and Technical Information of China (English)

    Guo TANG; Gui Ji ZHOU; Feng NI; Li Ming HU; Yu Fen ZHAO


    The intermediates of the Appel coupling reagents were studied in acetonitrile,dimethoxyethane and dioxane by 31P NMR, C NMR spectrum and ESI-MS. In dioxane a new high coordinated phosphorous compound with 31p NMR shift at -39 ppm was observed. The ESI-MS showed that it could be a penta-coordinated phosphorous compound containing dioxane. The carboxyl activated intermediates were also studied in three solvents.

  17. One-pot Synthesis of Lewis Acidic Ionic Liquids for Friedel-Crafts Alkylation

    Institute of Scientific and Technical Information of China (English)


    Novel Lewis acidic ionic liquids containing thionyl cations and chloroaluminate anions were obtained by one-pot synthesis for the first time. Their acidities were determined by acetonitrile probe on IR spectrography. The ionic liquids were used as catalyst for Friedel-Crafts alkylation of benzene and 1-dodecene. The turnovers of 1-dodecene were higher than 99%. Monoalkylbenzene selectivity was 98%, while the 2-substituent product selectivity was 45%.

  18. Atom transfer as a preparative tool in coordination chemistry. Synthesis and characterization of Cr(V) nitrido complexes of bidentate ligands

    DEFF Research Database (Denmark)

    Birk, Torben; Bendix, Jesper


    The transfer of a terminal nitrido ligand from MnV(N)(salen) to Cr(III) complexes is explored as a new preparative route to CrV nitrido complexes. Reaction of MnV(N)(salen) with labile CrCl3(THF)3 in acetonitrile solution precipitate [Mn(Cl)(salen)]·(CH3CN) and yields a solution containing a mixt...

  19. 40 CFR 60.489 - List of chemicals produced by affected facilities. (United States)


    ... acid. 108-24-7 Acetic anhydride. 67-64-1 Acetone. 75-86-5 Acetone cyanohydrin. 75-05-8 Acetonitrile. 98-86-2 Acetophenone. 75-36-5 Acetyl chloride. 74-86-2 Acetylene. 107-02-8 Acrolein. 79-06-1 Acrylamide...-4 Bromonaphthalene. 106-99-0 Butadiene. 106-98-9 1-butene. 123-86-4 n-butyl acetate. 141-32-2...

  20. 40 CFR Appendix IV to Part 266 - Reference Air Concentrations* (United States)


    ... No. RAC (ug/m3) Acetaldehyde 75-07-0 10 Acetonitrile 75-05-8 10 Acetophenone 98-86-2 100 Acrolein 107...-01-8 30 Carbon Disulfide 75-15-0 200 Chloral 75-87-6 2 Chlorine (free) 0.4 2-Chloro-1,3-butadiene 126... Cyanide (free) 57-12-15 20 Cyanogen 460-19-5 30 Cyanogen Bromide 506-68-3 80 Di-n-butyl Phthalate...

  1. 40 CFR 60.617 - Chemicals affected by subpart III. (United States)


    ... Acetic acid 64-19-7 Acetone 67-64-1 Acetonitrile 75-05-8 Acetophenone 98-86-2 Acrolein 107-02-8 Acrylic... 120-61-6 Ethylene dichloride 107-06-2 Ethylene oxide 75-21-8 Formaldehyde 50-00-0 Formic acid 64-18-6 Glyoxal 107-22-2 Hydrogen cyanide 74-90-8 Isobutyric acid 79-31-2 Isophthalic acid 121-91-5...

  2. 40 CFR Table 1 to Subpart Eeee of... - Organic Hazardous Air Pollutants (United States)


    ....2406. Compound name CAS No.1 2,4-D salts and esters 94-75-7 Acetaldehyde 75-07-0 Acetonitrile 75-05-8 Acetophenone 98-86-2 Acrolein 107-02-8 Acrylamide 79-06-1 Acrylic acid 79-10-7 Acrylonitrile 107-13-1 Allyl chloride 107-05-1 Aniline 62-53-3 Benzene 71-43-2 Biphenyl 92-52-4 Butadiene (1,3-) 106-99-0...

  3. Electrochemical evaluation of the p-Si/conducting polymer interfacial properties (United States)

    Nagasubramanian, G.; Distefano, S.; Moacanin, J.


    Results are presented from an experimental investigation of the contact resistance and interfacial properties of a p-Si/conducting polymer interface for solar cell applications. The electronic character of the polymer/semiconductor function is determined by studying the electrochemical behavior of both poly(isothianapthene) (PITN) and polypyrrole (PP) in an acetonitrile solution on p-silicon electrodes. The results obtained indicate that while PITN is intrinsically more conductive than PP, neither passivates surface states nor forms ohmic contact.

  4. Technical Report for the Period 1 January 1964 to 30 June 1964 (United States)


    apparently much larger. Too much weight should not be attached to the sliding block figure for barium styphnate , since all materials more sensitive than PET in...successful. Hydrazine Perchlorates )T R ICTS,D it has been found that all the hydrazine perchlorates are soluble in acetonitrile, as are barium ...than any RDX tested previously; dendritic RDX containing co-precipitated semi-colloidal graphite was less sensitive. Tribasic Lead Styphnate 2EST1’ICTED

  5. Polymerization of Pyrrole and Thiophene on Polyethylene Adipate Electrodes


    Erturan, Seyfettin; TORAMAN, Burcu YALVAÇ and Sena


    Polymerizations of pyrrole and thiophene on a platinum foil coated by polyethylene adipate (PEA) were carried out in acetonitrile by electrochemical methods. Different compositions of semi-conducting composite films of PEA/Polypyrrole(PPy), PEA/Polythiophene(PT) were prepared by the electrochemical polymerization of pyrrole and thiophene on PEA electrode. The polymerization was possible only for a certain thickness of the polyethylene adipate(PEA) on the platinum. Conductivities of PEA/PPy, P...

  6. An efficient synthesis of 2,2'-arylmethylene bis-(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) and 1,8-dioxooctahydroxanthenes using ZnO and ZnO-acetyl chloride

    Institute of Scientific and Technical Information of China (English)

    Malek; Habibi-Khorassani


    2,2'-Arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cycIohexene-l-one) 41-s produced from reaction between dimedone with various aldehydes in acetonitrile using ZnO as a catalyst; whereas in the presence of ZnO-acetyl chloride catalysts the reaction is limited to give only 1,8-dioxo-octahydroxanthenes 3a-k in very good yields.

  7. Heterogeneous batch distillation processes for waste solvent recovery in pharmaceutical industry


    Rodriguez-Donis, Ivonne; Gerbaud, Vincent; Arias-Barreto, Alien; Joulia, Xavier


    A summary about our experiences in the introduction of heterogeneous entrainers in azeotropic and extractive batch distillation is presented in this work. Essential advantages of the application of heterogeneous entrainers are showed by rigorous simulation and experimental verification in a bench batch distillation column for separating several azeotropic mixtures such as acetonitrile – water, n hexane – ethyl acetate and chloroform – methanol, commonly found in pharmaceutical industry.

  8. Estudo por espectrometria de massas de soluções de hidróxi(tosilóxiiodobenzeno: propostas para mecanismos de desproporção

    Directory of Open Access Journals (Sweden)

    Ramon S. Vasconcelos


    Full Text Available Solutions of [hydroxy(tosyloxyiodo]benzene (HTIB or Koser's reagent in acetonitrile were analyzed using high resolution electrospray ionization mass spectrometry (ESI-MS and electrospray ionization tandem mass spectrometry (ESI-MS/MS under different conditions. Several species were characterized in these analyses. Based on these data, mechanisms were proposed for the disproportionation of the iodine(III compounds in iodine(V and iodine(I species.

  9. Estudo por espectrometria de massas de soluções de hidróxi(tosilóxi)iodobenzeno: propostas para mecanismos de desproporção


    Vasconcelos, Ramon S.; Luiz F. Silva Jr.; Norberto P. Lopes


    STUDY BY MASS SPECTROMETRY OF SOLUTIONS OF [HYDROXY(TOSYLOXY)IODO]BENZENE: PROPOSED DISPROPORTIONATION MECHANISMS. Solutions of [hydroxy(tosyloxy)iodo]benzene (HTIB or Koser's reagent) in acetonitrile were analyzed using high resolution electrospray ionization mass spectrometry (ESI-MS) and electrospray ionization tandem mass spectrometry (ESI-MS/MS) under different conditions. Several species were characterized in these analyses. Based on these data, mechanisms were proposed for the dispropo...

  10. Synthesis optimization of 2-(4-N-[11C]methylaminophenyl)-6-hydroxybenzothiazole ([11C]PIB), β-amyloid PET imaging tracer for Alzheimer's disease diagnosis. (United States)

    Coliva, A; Monterisi, C; Apollaro, A; Gatti, D; Penso, M; Gianolli, L; Perani, D; Gilardi, M C; Carpinelli, A


    [11C]PIB is the most used amyloid plaques-specific positron-emitting radiotracers. The radiosynthesis of this compound, carried out by methylation of its precursor with [11C]methyl triflate in 2-butanone, has been improved optimizing the initial concentration and the purification method. Two HPLC methods were compared: good radiochemical yields, specific activities, and chemical purity above 98% were achieved by using as eluant acetonitrile/citrate and formulation in 10% ethanol.

  11. Comparative method validation for closantel determination in cattle and sheep milk according to European Union Volume 8 and Veterinary International Conference on Harmonization guidelines. (United States)

    Devreese, Mathias; Maes, An; De Baere, Siegrid; De Backer, Patrick; Croubels, Siska


    A specific and sensitive LC-MS/MS method was developed for quantitative determination of closantel in bovine and ovine colostrum and tank milk. Sample preparation consisted of extracting milk samples with acetonitrile/acetone (80/20, v/v) followed by SPE clean-up with Oasis mixed anion exchange columns. After elution with 5% formic acid in acetonitrile and evaporation to dryness, the residue was reconstituted in acetonitrile and water. HPLC separation was achieved on a Zorbax Eclipse Plus C18 column and a gradient elution program with 1mM ammonium acetate in water and acetonitrile. For closantel determination in bovine milk, the method was validated according to EU Volume 8 guidelines whereas for ovine milk both EU Volume 8 and VICH GL49 criteria were applied. The linear range of the method is between 10 and 2000 μg/kg, the limit of quantification 10 μg/kg and limit of detection is 0.63 and 0.32 μg/kg for sheep colostrum and tank milk and 1.27 and 1.24 μg/kg for cattle colostrum and tank milk, respectively. Both guidelines cover a similar set of parameters (linearity, accuracy, precision, limit of detection and limit of quantification), although the acceptance criteria might differ (accuracy and precision) or no specific acceptability ranges are specified in neither guidelines (LOD and LOQ). For some parameters, only one of the guidelines indicates acceptance criteria: EU Volume 8 for applicability, practicability and susceptibility and VICH GL 49 for linearity, specificity and analyte stability.

  12. Physicochemical properties of the surfaces of silica species (United States)

    Roshchina, T. M.; Shoniya, N. K.; Tegina, O. Ya.; Tkachenko, O. P.; Kustov, L. M.


    The results from studying the physicochemical characteristics of the adsorption of n-alkanes, arenes, and acetonitrile on silicas of different origins, silica gels, and silochromes are presented. It is shown that increasing the concentration of silanol groups reduces the role of dispersion interactions accompanied by the intensification of specific interactions on silica gels, compared to silochromes. According to diffuse reflectance FTIR spectroscopy data, the acidity of silanol groups on silica gel is in this case less pronounced.

  13. Hydrophilic interaction liquid chromatography in analysis of granisetron HCl and its related substances. Retention mechanisms and method development. (United States)

    Maksić, Jelena; Tumpa, Anja; Stajić, Ana; Jovanović, Marko; Rakić, Tijana; Jančić-Stojanović, Biljana


    In this paper separation of granisetron and its two related substances in HILIC mode is presented. Separation was done on silica column derivatized with sulfoalkylbetaine groups (ZIC-HILIC). Firstly, retention mechanisms were assessed whereby retention factors of substances were followed in wide range of acetonitrile content (80-97%), at constant concentration of aqueous buffer (10mM) as well as at constant pH value of 3.0. Further, in order to developed optimal HILIC method, Design of Experiments (DoE) methodology was applied. For optimization full factorial design 3(2) was employed. Influence of acetonitrile content and ammonium acetate concentration were investigated while pH of the water phase was kept at 3.3. Adequacy of obtained mathematical models was confirmed by ANOVA. Optimization goals (α>1.15 and minimal run time) were accomplished with 94.7% of acetonitrile in mobile phase and 70 mM of ammonium acetate in water phase. Optimal point was in the middle of defined Design Space. In the next phase, robustness was experimetally tested by Rechtschaffen design. The investigated factors and their levels were: acetonitrile content (±1%), ammonium acetate molarity in water phase (±2 mM), pH value of water phase (±0.2) and column temperature (±4 °C). The validation scope included selectivity, linearity, accuracy and precision as well as determination of limit of detection (LOD) and limit of quantification (LOQ) for the related substances. Additionally, the validation acceptance criteria were met in all cases. Finally, the proposed method could be successfully utilized for estimation of granisetron HCl and its related substances in tablets and parenteral dosage forms, as well as for monitoring degradation under various stress conditions.

  14. Environmental Compliance Assessment and Management Program (United States)


    2.12. Carcinogenic Hazardous Air Pollutant - any hazardous air pollutant recognized as known, prob- able, or potential human carcinogen by the U.S...Acetamide 60355 Acetonitrile 75058 Acetophenone 98862 2-Acetylaminofluorene 53963 Acrolein 107028 Acrylamide 79061 Acrylic acid 79107 Acrylonitrile effects following short-term exposure from accidental releases and which are listed in Part 355 of 40 Code of Federal Regulations (CFR). 3.3

  15. Synthesis, complexation, and fluorescence behavior of 3,4-dimethylthieno[2,3-b]thiophene carrying two monoaza-15-crown-5 ether groups (United States)

    Wu, Yong Xiang; Cao, Jing; Deng, Hai Yan; Feng, Jun Xiang


    A novel fluoroionophore 1 based on 3,4-dimethylthieno[2,3-b]thiophene bearing two monoaza-15-crown-5 ethers at 3- and 4-positions was prepared. UV-vis and fluorescence responses of compound 1 upon the addition of alkali and alkaline earth metal cations were evaluated in acetonitrile solution. Receptor 1 showed unique response for Ba 2+ due to the formation of an intramolecular sandwich complex.

  16. Simultaneous determination of a quaternary mixture of oxomemazine, sodium benzoate, guaifenesin and paracetamol by chromatographic methods


    Nehal F. Farid; Nariman A. El Ragehy; Maha A. Hegazy; Mohamed Abdelkawy; Fadia H. Metwally


    The aim of the present work was to develop simple, accurate, sensitive and selective methods for the simultaneous determination of oxomemazine (Ox), sodium benzoate (SB), guaifenesin (Gu), andparacetamol (Par). Two methods were described and validated for the simultaneous determination of the four drugs in syrup and suppositories. The first method was a reversed phase HPLC and UVdetection at 220 nm. The assay was performed using C 18 column and an isocratic elution using acetonitrile – methan...

  17. Formaldehyde Five-Day Passive Chemical Dosimeter Badge Validation Study (United States)


    DNPH-cartridges. ............................... 7 Figure 8 Example of commercially available packed granular potassium iodide (KI) ozone scrubber...Example of commercially available packed granular potassium iodide (KI) ozone scrubber. Figure 9 Example of configuration of a single-port carbonyl...formaldehyde vapor stream. Formaldehyde-DNPH at 500 µg/mL (as aldehyde) in acetonitrile was purchased from Cerilliant Corporation, Round Rock, TX. Potassium

  18. Investigation of Photoelectrode Redox Polymer Junctions (United States)


    used for the cyclic voltammetry scans. RESULTS AND DISCUSSION Cell Preparatton Solid-state PEC cells were fabricated by introducing .05ml of a solution...Electrochemical measurements were performed using potentiostatic control provided by either a Stonehart Associates BC 1200 or a Wenking LT 78 poten- tiostat...ELH bulb. Light intensities were measured with an Eppley 8-48 pyranometer. Cyclic voltammograms on the redox couples were run in acetonitrile S

  19. Conformational control in a bipyridine linked π-conjugated oligomer: cation mediated helix unfolding and refolding. (United States)

    Divya, Kizhumuri P; Sreejith, Sivaramapanicker; Suresh, Cherumuttathu H; Ajayaghosh, Ayyappanpillai


    A chiral π-conjugated oligomer having alternate bipyridine and carbazole moieties connected through acetylinic bonds undergoes helical folding in chloroform-acetonitrile (40/60, v/v) as evident by fluorescence and circular dichroism changes. In the presence of transition metal cations such as Zn(2+) defolding of the helical conformation occurs. Upon decomplexation of the cation with EDTA, the helical conformation is regained.

  20. Boric acid as cost-effective and recyclable catalyst for trimethylsilyl protection and deprotection of alcohols and phenols

    Energy Technology Data Exchange (ETDEWEB)

    Rostami, Amin; Akradi, Jamal; Ahmad-Jangi, Firoz, E-mail: [University of Kurdistan, Sanandaj (Iran, Islamic Republic of). Faculty of Science. Dept. of Chemistry


    Boric acid has been used as a green, selective and recyclable catalyst for trimethysilylation of alcohols and phenols using hexamethyldisilazane in acetonitrile. Deprotection of trimethylsilyl ethers to their parent alcohols and phenols was also achieved using this catalyst in water at room temperature. The salient features of this methodology are cheap processing, mild acidity conditions, excellent yields of products and easy availability of the catalyst. (author)