WorldWideScience

Sample records for catalyzed semi-batch ethoxylation

  1. Thermally safe operation of a cooled semi-batch reactor: slow liquid-liquid reactions

    NARCIS (Netherlands)

    Steensma, M.; Westerterp, K.R.

    1988-01-01

    Thermally safe operation of a semi-batch reactor (SBR) implies that conditions leading to strong accumulation of unreacted reactants must be avoided. All thermal responses of a SBR, in which a slow liquid-liquid reaction takes place, can be represented in a diagram with the kinetics, cooling capacit

  2. Monte Carlo simulation on kinetics of batch and semi-batch free radical polymerization

    KAUST Repository

    Shao, Jing

    2015-10-27

    Based on Monte Carlo simulation technology, we proposed a hybrid routine which combines reaction mechanism together with coarse-grained molecular simulation to study the kinetics of free radical polymerization. By comparing with previous experimental and simulation studies, we showed the capability of our Monte Carlo scheme on representing polymerization kinetics in batch and semi-batch processes. Various kinetics information, such as instant monomer conversion, molecular weight, and polydispersity etc. are readily calculated from Monte Carlo simulation. The kinetic constants such as polymerization rate k p is determined in the simulation without of “steady-state” hypothesis. We explored the mechanism for the variation of polymerization kinetics those observed in previous studies, as well as polymerization-induced phase separation. Our Monte Carlo simulation scheme is versatile on studying polymerization kinetics in batch and semi-batch processes.

  3. Thermally safe operation of a cooled semi-batch reactor: slow liquid-liquid reactions

    OpenAIRE

    Steensma, M.; Westerterp, K R

    1988-01-01

    Thermally safe operation of a semi-batch reactor (SBR) implies that conditions leading to strong accumulation of unreacted reactants must be avoided. All thermal responses of a SBR, in which a slow liquid-liquid reaction takes place, can be represented in a diagram with the kinetics, cooling capacity and potential temperature rise as the keyfactors. Slow reactions taking place in the dispersed phase were found to be more prone to accumulation than reactions in the continuous phase. An overhea...

  4. Enhancement of a semi-batch chemical reactor efficiency through its dimensions optimization

    OpenAIRE

    Macků, Lubomír; Novosad, David

    2015-01-01

    Efficiency of manufacturing processes is very important in today's competitive world with hard economic rules. In chemical engineering area the efficiency depends on the production heart, which is often a chemical reactor. In this paper authors describe process of optimal semi-batch exothermic reactor dimensions finding. The task is to find reactor dimensions which lead to process efficiency improving, i.e. to processing the greater chemicals amount in the same or shorter time. The optimizing...

  5. Perancangan Sistem Pengukuran pH dan Temperatur Pada Bioreaktor Anaerob Tipe Semi-Batch

    OpenAIRE

    Dimas Prasetyo Oetomo; Totok Soehartanto

    2013-01-01

    Proses pada bioreaktor dapat dilakukan secara aerob yaitu menggunakan bantuan oksigen dan anaerob yaitu tidak menggunakan bantuan oksigen. Pada penelitian ini dilakukan fermentasi  enceng gondok untuk menghasilkan biogas menggunakan bioreaktor anaerob tipe semi-batch. Enceng gondok memiliki rasio C/N sebesar 22.5 – 35.84% yang merupakan komposisi optimum untuk ekstraksi biogas. Kinerja dari bioreaktor dalam produksi biogas dipengaruhi oleh beberapa parameter seperti pH dan temperatur. Pada pe...

  6. Semi-batch Crystallization of 7-Amino-Desacetoxycephalos-poranic Acid

    Institute of Scientific and Technical Information of China (English)

    王静廉; 刘越

    2003-01-01

    Semi-batch crystallization of 7-amino-desacetoxycephalosporanic acid (7-ADCA) is a complicated process, in which agglomeration occurs together with nucleation and crystal growth. To systematically study such a process, experiments were conducted to estimate the crystallization thermodyneanics and kinetics, and then the process was simulated by a numerical method. The application of Monte Carlo concept in the algorithm to describe agglomeration event offers an alternative approach of solving the population balance, the intrinsic simplicity of which allows us to investigate several mechanisms and include several internal coordinates in the analysis. Furthermore,present study may be a valuable paradigm for other semi-hatch crystallization processes.

  7. Optimal iterative learning control for end-point product qualities in semi-batch process based on neural network model

    Institute of Scientific and Technical Information of China (English)

    XIONG ZhiHua; DONG Jin; ZHANG Jie

    2009-01-01

    An optimal iterative learning control (ILC) strategy of improving endpoint products in semi-batch processes is presented by combining a neural network model. Control affine feed-forward neural network (CAFNN) is proposed to build a model of semi-batch process. The main advantage of CAFNN is to obtain analytically its gradient of endpoint products with respect to input. Therefore, an optimal ILC law with direct error feedback is obtained explicitly, and the convergence of tracking error can be analyzed theoretically. It has been proved that the tracking errors may converge to small values. The proposed modeling and control strategy is illustrated on a simulated isothermal semi-batch reactor, and the results show that the endpoint products can be improved gradually from batch to batch.

  8. FBRM and PVM investigations of the double feed semi-batch crystallization of 6-aminopenicillanic acid

    Institute of Scientific and Technical Information of China (English)

    Min SU; Lin WANG; Hua SUN; Jingkang WANG

    2009-01-01

    6-Aminopenicillanic acid (6-APA) is a crucial pharmaceutical intermediate in the chemistry of semi-synthetic antibiotics. The focused beam reflectance measurement (FBRM) technology and particle vision measurement (PVM) technology were employed to the processes of online-monitoring of 6-APA crystallization behavior in a double-feeding semi-batch crystallizer. Experiments were carried out with four kinds of double-feeding policies and the results were compared with the traditional single-feeding. Records and analysis of FBRM indicated that the nucleation of double feeding policy was much higher than single policy, and chord length of 6-APA was almost determined and had little change after the nucleation peak. Ostwald ripening process had no significant effect on further growth of 6-APA crystal. PVM images showed that the crystal habit of 6-APA was continuously changed during the crystallization process. The development of (002) face in the final crystal for the five feeding policies were different.

  9. Energy efficiency of batch and semi-batch (CCRO) reverse osmosis desalination.

    Science.gov (United States)

    Warsinger, David M; Tow, Emily W; Nayar, Kishor G; Maswadeh, Laith A; Lienhard V, John H

    2016-12-01

    As reverse osmosis (RO) desalination capacity increases worldwide, the need to reduce its specific energy consumption becomes more urgent. In addition to the incremental changes attainable with improved components such as membranes and pumps, more significant reduction of energy consumption can be achieved through time-varying RO processes including semi-batch processes such as closed-circuit reverse osmosis (CCRO) and fully-batch processes that have not yet been commercialized or modelled in detail. In this study, numerical models of the energy consumption of batch RO (BRO), CCRO, and the standard continuous RO process are detailed. Two new energy-efficient configurations of batch RO are analyzed. Batch systems use significantly less energy than continuous RO over a wide range of recovery ratios and source water salinities. Relative to continuous RO, models predict that CCRO and batch RO demonstrate up to 37% and 64% energy savings, respectively, for brackish water desalination at high water recovery. For batch RO and CCRO, the primary reductions in energy use stem from atmospheric pressure brine discharge and reduced streamwise variation in driving pressure. Fully-batch systems further reduce energy consumption by not mixing streams of different concentrations, which CCRO does. These results demonstrate that time-varying processes can significantly raise RO energy efficiency. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. SEMI-BATCH OPERATED CONSTRUCTED WETLANDS PLANTED WITH PHRAGMITES AUSTRALIS FOR TREATMENT OF DYEING WASTEWATER

    Directory of Open Access Journals (Sweden)

    SOON-AN ONG

    2011-10-01

    Full Text Available The objective of present study is to evaluate the using of constructed wetland under semi-batch operation for the treatment of azo dye Acid Orange 7 (AO7 containing wastewater. The emergent plant selected in our study was Phragmites australis. Toxic signs were observed at the Phragmites australis after the addition of AO7 into the wetland reactors but it can adapt to the wastewater as shown in the increase of stem as the operation continue. Our result shows that the artificial aeration and the presence of Phragmites australis had a significant impact on the removal of organic matters, AO7, aromatic amines and NH4-N. The COD removal efficiency in the aerated and non-aerated wetland reactors was 95 and 62%, respectively. The NH4-N removal efficiency in the aerated wetland reactor (86% was significantly higher than the non-aerated wetland reactor (14 %. All wetland reactors show high removal efficiency of AO7 (> 94% but only the aerated wetland reactor perform better in the removal of aromatic amines.

  11. Perancangan Sistem Pengukuran pH dan Temperatur Pada Bioreaktor Anaerob Tipe Semi-Batch

    Directory of Open Access Journals (Sweden)

    Dimas Prasetyo Oetomo

    2013-12-01

    Full Text Available Proses pada bioreaktor dapat dilakukan secara aerob yaitu menggunakan bantuan oksigen dan anaerob yaitu tidak menggunakan bantuan oksigen. Pada penelitian ini dilakukan fermentasi  enceng gondok untuk menghasilkan biogas menggunakan bioreaktor anaerob tipe semi-batch. Enceng gondok memiliki rasio C/N sebesar 22.5 – 35.84% yang merupakan komposisi optimum untuk ekstraksi biogas. Kinerja dari bioreaktor dalam produksi biogas dipengaruhi oleh beberapa parameter seperti pH dan temperatur. Pada penelitian ini dilakukan perancangan sistem pengukuran besaran pH dan temperatur secara online sehingga memudahkan dalam pengambilan data. Bahan yang digunakan pada proses fermentasi adalah campuran enceng gondok yang telah dicincang dan dicampur air dengan dua komposisi penambahan berbeda untuk dibandingkan. Pada Bioreaktor1 digunakan komposisi enceng gondok dan air sebesar 1:3 dan pada bioreaktor 2 digunakan komposisi enceng gondok dan air sebesar 0,75: 1,25. Hasil penelitian menyebutkan bahwa bioreaktor 2 dengan komposisi enceng gondok dan air sebesar 0,75: 1,25 menghasilkan biogas lebih aktif dibandingkan dengan bioreaktor 1 dengan komposisi enceng gondok dan air sebesar 1 : 3. Hal tersebut diketahui dari hasil pengukuran selama 76 hari. Dari hasil pengukuran juga diketahui bahwa penurunan nilai COD pada bioreaktor 2 lebih besar dari pada  bioreaktor 1.

  12. Evaluation of Critical Operating Conditions for a Semi-batch Reactor by Complementary Use of Sensitivity and Divergence Criteria

    OpenAIRE

    Maria, G; Stefan, D.-N.

    2011-01-01

    This paper presents a comparison of several effective methods of deriving the critical feeding conditions for the case of a semi-batch catalytic reactor used for the acetoacetylation of pyrrole with diketene in homogeneous liquid phase. The reaction is known to be of high risk due to the very exothermic (polymerisation) side-reactions involving reactive diketene. In order to perform the sensitivity analysis, both the Morbidelli-Varma sensitivity criterion and div-methods were used, the latter...

  13. Runaway behavior and thermally safe operation of multiple liquid–liquid reactions in the semi-batch reactor: The nitric acid oxidation of 2-octanol

    NARCIS (Netherlands)

    Woezik, van B.A.A.; Westerterp, K.R.

    2002-01-01

    The thermal runaway behavior of an exothermic, heterogeneous, multiple reaction system has been studied in a cooled semi-batch reactor. The nitric acid oxidation of 2-octanol has been used to this end. During this reaction, 2-octanone is formed, which can be further oxidized to unwanted carboxylic a

  14. Semi-Batch Deoxygenation of Canola- and Lard-Derived Fatty Acids to Diesel-Range Hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Ford, JP; Thapaliya, N; Kelly, MJ; Roberts, WL; Lamb, HH

    2013-12-01

    Fatty acids (FAs) derived via thermal hydrolysis of food-grade lard and canola oil were deoxygenated in the liquid phase using a commercially available 5 wt % Pd/C catalyst. Online quadrupole mass spectrometry and gas chromatography were used to monitor the effluent gases from the semi-batch stirred autoclave reactors. Stearic, oleic, and palmitic acids were employed as model compounds. A catalyst lifetime exceeding 2200 turnovers for oleic acid deoxygenation was demonstrated at 300 degrees C and 15 atm under 10% H-2. The initial decarboxylation rate of palmitic acid under 5% H-2 decreases sharply with increasing initial concentration; in contrast, the initial decarbonylation rate increases linearly, indicative of first-order kinetics. Scale-up of diesel-range hydrocarbon production was investigated by increasing the reactor vessel size, initial FA concentration, and FA/catalyst mass ratio. Lower CO2 selectivity and batch productivity were observed at the larger scales (600 and 5000 mL), primarily because of the higher initial FA concentration (67 wt %) employed. Because unsaturated FAs must be hydrogenated before deoxygenation can proceed at an appreciable rate, the additional batch time required for FA hydrogenation reduces the batch productivity for unsaturated feedstocks. Low-temperature hydrogenation of unsaturated feedstocks (using Pd/C or another less-expensive catalyst) prior to deoxygenation is recommended.

  15. Oxidation pathways for ozonation of azo dyes in a semi-batch reactor: a kinetic parameters approach.

    Science.gov (United States)

    Lopez, A; Benbelkacem, H; Pic, J S; Debellefontaine, H

    2004-03-01

    In this study ozone and the H2O2/O3 oxidation system are used to decolorize aqueous solutions of Orange II (Or-II) and Acid Red 27 (AR-27). Investigations are carried out in a semi-batch bubble column reactor. A system of series-parallel reactions is proposed to describe the mechanism of dye oxidation. The stoichiometric ratio for the first reaction is found to be 1 mol dye per mol O3, while the overall ozone demand for both reactions one and two is found to be 5 and 6 moles for Or-II and AR-27 respectively. Molecular and radical kinetics are compared: a radical scavenger, t-butanol, can be added to ensure only the molecular reaction of ozone, or hydrogen peroxide can be supplied through a peristaltic pump, to initiate radical reactivity. Results reveal that colour removal is ensured by direct ozone attack. For both dyes, TOC removal efficiencies of 50 - 60 % are obtained by the action of the hydroxyl free radical. However, this is not improved by addition of H2O2, thus demonstrating that organic species alone ensure HO degrees radical production during ozonation. Both the mass transfer and the ozone reactivity with the dyes are considered to evaluate the kinetic parameters for the molecular pathway.

  16. In-situ catalytic synthesis of ammonia from urea in a semi-batch reactor for safe utilization in thermal power plant

    Energy Technology Data Exchange (ETDEWEB)

    J.N. Sahu; A.V. Patwardhan; B.C. Meikap [Indian Institute of Technology (IIT), Kharagpur (India). Department of Chemical Engineering

    2010-05-15

    Urea as the source of ammonia for the flue gas conditioning/NOx reduction system in thermal power plant has the obvious advantages that no ammonia shipping, handling and storage is required. The process of this invention minimizes the risks and hazards associated with the transport, storage and use of anhydrous and aqueous ammonia, as ammonia is a highly volatile noxious material. But no such rapid urea conversion process is available as per requirement of high conversion in shorter time, so here we study the catalytic hydrolysis of urea for fast conversion in a semi-batch reactors. The catalysts used in this study are: TiO{sub 2}, fly ash, mixture of Ni and Fe and Al{sub 2}O{sub 3}.A number of experiments was carried out in a semi-batch reactor at different catalyst doses, temperatures and concentration of urea solution from 10 to 30% by weight and equilibrium study has been made.

  17. Effect of using batch or semi-batch reactor on the chemical composition distribution of styrene-maleic anhydride-acrylonitrile terpolymers

    OpenAIRE

    Cunha, Regina de J. S.; Ailton S. Gomes

    1997-01-01

    Texto completo: acesso restrito. p.595-600 The influence of the reactor type on distribution of chemical composition of STY AN/MA terpolymers obtained by free-radical polymerization is shown. When a batch reactor was used we have obtained polymers with broad chemical composition distribution. However, if a semi-batch reactor with appropriate addition protocol was used it can be possible to synthesize terpolymers with homogeneous chemical composition.

  18. Model-based Derivation of the Safety Operating Limits of a Semi-batch Reactor for the Catalytic Acetoacetylation of Pyrrole Using a Generalized Sensitivity Criterion

    OpenAIRE

    Maria, G; A Dan; Stefan, D.-N.

    2010-01-01

    The safe operation of a semi-batch catalytic reactor remains a sensitive issue when highly exothermic side reactions may occur, and various elements such as controllability, stability, safety, and economic aspects have to be considered in the process development. Nominal operating conditions are set to avoid excessive thermal sensitivity to variations in the process parameters. Several shortcuts or model-based methods are used to estimate the safety limits and runaway boundaries for the op...

  19. Time programmed feed of semi-batch reactors with non-linear radical copolymerizations: an experimental study of the system styrene+divinylbenzene using SEC/MALLS

    OpenAIRE

    Gonçalves, Miguel; Dias, Rolando; Costa, Mário Rui

    2007-01-01

    The radical crosslinking copolymerization of mono and divinyl monomers was experimentally studied with a 2.5 dm3 semi-batch reactor using styrene + divinylbenzene as a model system. The analysis of products was carried out by SEC with a MALLS detector. The influence of the feed policy of divinylbenzene on the time evolution of the copolymer molecular weights and z-average mean square radius of gyration was assessed. A detailed kinetic model, in the absence of intramolecular reactions but taki...

  20. Equilibrium studies on hydrolysis of urea in a semi-batch reactor for production of ammonia to reduce hazardous pollutants from flue gases

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, J.N.; Mahalik, K.K.; Patwardhan, A.V. [Department of Chemical Engineering, Indian Institute of Technology (IIT) Kharagpur, P.O. Kharagpur Technology, Kharagpur, West Bengal 721302 (India); Meikap, B.C., E-mail: bcmeikap@iitkgp.ac.in [Department of Chemical Engineering, Indian Institute of Technology (IIT) Kharagpur, P.O. Kharagpur Technology, Kharagpur, West Bengal 721302 (India)

    2009-05-30

    The increasing environmental awareness and the mandate of the pollution control agencies in various part of country for lowering emission of air pollutants such as CO{sub 2}, NO{sub x}, SO{sub 2} and fly ash emissions, has increased the urgency for reviewing options and alternatives to accomplish the above objective. The addition of ammonia into the flue gas stream as a conditioning agent is found to be used in recent years for the reduction of air pollutants. Flue gas conditioning requires in situ generation of ammonia as the transportation and storage of anhydrous ammonia is hazardous in nature. The equilibrium study on hydrolysis of urea was done in a semi-batch glass reactor to investigate the effect of reaction temperature, initial feed concentration and stirring speed on ammonia production. Few experiments were carried out in a semi-batch reactor at atmospheric pressure by using different concentration of urea solution from 10 to 40 wt% of urea to water and equilibrium study has been done. The study reveals that conversion increases exponentially with an increase in temperature but the conversion decreases with increase in the inlet feed concentration of urea solution. Furthermore, the effect of stirring speed on conversion has also been studied and it found that conversion increases with increase in stirring speed.

  1. 40 CFR 721.4365 - Substituted ethoxylated hydrocarbon (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Substituted ethoxylated hydrocarbon... Specific Chemical Substances § 721.4365 Substituted ethoxylated hydrocarbon (generic). (a) Chemical... as Substituted ethoxylated hydrocarbon (PMN P-99-0313) is subject to reporting under this section...

  2. Titration procedure for low ethoxylated nonionic surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Buschmann, N. [Anorganisch-Chemisches Inst., Lehrstuhl fuer Analytische Chemie, Muenster Univ. (Germany); Huelskoetter, F. [Anorganisch-Chemisches Inst., Lehrstuhl fuer Analytische Chemie, Muenster Univ. (Germany)

    1997-01-01

    Highly lipophilic surfactants are frequently used as emulsifiers for preparing oil-in-water emulsions (e.g. coolants lubricants). Typical surfactants used for this purpose are low ethoxylated alcohols and ethoxylated alkylphenols. Due to the low degree of ethoxylation they cannot be analysed by conventional methods. The method described in this article is based on the introduction of an anionic group into the molecule by a derivatization reaction. The reaction product can be determined by conventional titration methods for anionic surfactants without any modification. The use of the new method for other nonionic surfactants like sorbitan esters, (ethoxylated) fatty acid amides or glycerol fatty acid partial esters is also described as well as the sample preparation for coolants lubricants. (orig.) [Deutsch] Lipophile Tenside werden haeufig zur Herstellung von Oel-in-Wasser-Emulsionen verwandt, wie sie beispielsweise in Kuehlschmiermitteln eingesetzt werden. Typische Vertreter dieser Tenside sind niedrig ethoxylierte Fettalkohole und Alkylphenole. Wegen ihres geringen Ethoxylierungsgrades koennen sie mit den konventionellen Methoden nicht analytisch bestimmt werden. Die hier beschriebene Analysenmethode beruht auf der Derivatisierung der Ethoxylate zu entsprechenden anionischen Tensiden (Ethersulfate). Diese koennen ohne weiteres mit den etablierten Titrationsverfahren bestimmt werden. Die Anwendung dieses neuen Verfahrens auf die Bestimmung anderer nichtionischer Tenside - Sorbitanester, (ethoxylierte) Fettsaeureamide und Partialglyceride - wird ebenso beschrieben wie die Probenvorbereitung fuer die Analyse von Kuehlschmiermitteln. (orig.)

  3. Nature of the Intermicellar Interactions in Ethoxylated Polysorbate Surfactants with High Degrees of Ethoxylation.

    Science.gov (United States)

    Penfold, J; Thomas, R K; Li, P X; Tucker, I; Petkov, J; Petkova, R E

    2016-02-09

    Ethoxylated polysorbate Tween nonionic surfactants are extensively used as foam and emulsion stabilizers and in aqueous solution form globular micelles. The ethoxylated polysorbate surfactants with higher degrees of ethoxylation than the Tween surfactants exhibit some interesting self-assembly properties. Small-angle neutron scattering, SANS, measurements have revealed intermicellar interactions which are more pronounced than the hard-sphere excluded volume interactions normally associated with nonionic surfactant micelles. The interactions are interpreted as arising from the partial charge on the ether oxygen of the ethylene oxide groups. This gives rise to an effective net negative charge on the micelles, which has been determined from the SANS data and zeta potential measurements. For degrees of ethoxylation of ⩽20, the effect is relatively small. The interaction increases with increasing ethoxylation such that for a degree of ethoxylation of 50 the interaction is comparable to that of ionic surfactant micelles. Unlike the intermicellar interaction in ionic surfactant micellar solutions, which results from the charge on the micelle arising from the partial binding of counterions, the interaction between ethoxthylated polysorbate surfactant micelles is unaffected by the addition of electrolyte.

  4. 7-氨基去乙酰氧基头孢菌素半间歇反应结晶过程%Semi-batch Crystallization of 7-Amino-Desacetoxycephalosporanic Acid

    Institute of Scientific and Technical Information of China (English)

    王静康; 刘越

    2003-01-01

    Semi-batch crystallization of 7-amino-desacetoxycephalosporanic acid (7-ADCA) is a complicated pro-cess, in which agglomeration occurs together with nucleation and crystal growth. To systematically study such aprocess, experiments were conducted to estimate the crystallization thermodynamics and kinetics, and then theprocess was simulated by a numerical method. The application of Monte Carlo concept in the algorithm to describeagglomeration event offers an alternative approach of solving the population balance, the intrinsic simplicity of whichallows us to investigate several mechanisms and include several internal coordinates in the analysis. Furthermore,present study may be a valuable paradigm for other semi-batch crystallization processes.

  5. Ethoxylated rapeseed oil derivatives as novel adjuvants for herbicides.

    Science.gov (United States)

    Müller, Thomas; Brancq, Bernard; Milius, Alain; Okori, Nathalie; Vaille, Claude; Gauvrit, Christian

    2002-12-01

    Ethoxylates of rapeseed oil and of methylated rapeseed oil were synthesized and tested as adjuvants for 2,4-D and phenmedipham. Provided they had less than 6 units of ethylene oxide (EO), 1.0 to 10 g litre(-1) ethoxylates in water induced droplet spreading on barley leaves. In an acetone-based medium all derivatives strongly promoted the foliar uptake of 2,4-D, with no clear influence of the ethoxylation degree. In the same medium there was a negative influence of ethoxylate chain length on the foliar uptake of phenmedipham. In a water-based medium, phenmedipham applied with rapeseed oil emulsified with ethoxylated (20 EO) rapeseed oil displayed uptake rates close to a commercial preparation. The same was true for phenmedipham applied with ethoxylated (2 EO) methylated rapeseed oil. In bioassays, phenmedipham prepared with methylated rapeseed oil emulsified with ethoxylated (20 EO) rapeseed oil was as efficacious on barley as a commercial formulation. The same was true for phenmedipham prepared with ethoxylated (2 EO) methylated rapeseed oil. However, neither rapeseed oil nor methylated rapeseed oil emulsified with ethoxylated (2 EO) methylated rapeseed oil conferred good efficacy to phenmedipham. Hence, ethoxylated rapeseed oil derivatives are promising adjuvants or formulants for herbicides.

  6. Comparison of semi-batch vs. continuously fed anaerobic bioreactors for the treatment of a high-strength, solids-rich pumpkin-processing wastewater.

    Science.gov (United States)

    del Agua, Isabel; Usack, Joseph G; Angenent, Largus T

    2015-01-01

    The objective of this work was to compare two different high-rate anaerobic bioreactor configurations--the anaerobic sequencing batch reactor (ASBR) and the upflow anaerobic solid removal (UASR) reactor--for the treatment of a solid-rich organic wastewater with a high strength. The two, 4.5-L reactors were operated in parallel for close to 100 days under mesophilic conditions (37°C) with non-granular biomass by feeding a pumpkin wastewater with ∼4% solids. The organic loading rate of pumpkin wastewater was increased periodically to a maximum of 8 g COD L(-1) d(-1) by shortening the hydraulic retention time to 5.3 days. Compositional analysis of pumpkin wastewater revealed deficiencies in the trace metal cobalt and alkalinity. With supplementation, the ASBR outperformed the UASR reactor with total chemical oxygen demand (COD) removal efficiencies of 64% and 53%, respectively, achieving a methane yield of 0.27 and 0.20 L CH4 g(-1) COD fed to the ASBR and UASR, respectively. The better performance realized with the ASBR and this specific wastewater was attributed to its semi-batch, dynamic operating conditions rather than the continuous operating conditions of the UASR reactor.

  7. 40 CFR 721.5970 - Phosphated polyarylphenol ethoxylate, potassium salt.

    Science.gov (United States)

    2010-07-01

    ..., potassium salt. 721.5970 Section 721.5970 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5970 Phosphated polyarylphenol ethoxylate, potassium salt. (a) Chemical... as phosphated polyarylphenol ethoxylate, potassium salt (PMN P-93-1222) is subject to reporting under...

  8. Impact of the degree of ethoxylation of the ethoxylated polysorbate nonionic surfactant on the surface self-assembly of hydrophobin-ethoxylated polysorbate surfactant mixtures.

    Science.gov (United States)

    Penfold, Jeffrey; Thomas, Robert K; Li, Peixun; Petkov, Jordan T; Tucker, Ian; Cox, Andrew R; Hedges, Nick; Webster, John R P; Skoda, Maximilian W A

    2014-08-19

    Neutron reflectivity measurements have been used to study the surface adsorption of the polyethylene sorbitan monostearate surfactant, with degrees of ethoxylation varying from 3 to 20 ethylene oxide groups, with the globular protein hydrophobin. The surface interaction between the ethoxylated polysorbate nonionic surfactants and the hydrophobin results in self-assembly at the air-solution interface in the form of a well-defined layered surface structure. The surface interaction arises from a combination of the hydrophobic interaction between the surfactant alkyl chain and the hydrophobic patch on the surface of the hydrophobin, and the hydrophilic interaction between the ethoxylated sorbitan headgroup and the hydrophilic regions on the surface of the hydrophobin. The results presented show that varying the degree of ethoxylation of the polysorbate surfactant changes the interaction between the surfactant and the hydrophobin and the packing, and hence the evolution in the resulting surface structure. The optimal degree of ethoxylation for multilayer formation is over a broad range, from of order 6 to 17 ethylene oxide groups, and for degrees of ethoxylation of 3 and 20 only monolayer adsorption of either the surfactant or the hydrophobin is observed.

  9. 21 CFR 172.834 - Ethoxylated mono- and diglycerides.

    Science.gov (United States)

    2010-04-01

    ... ethoxylated mono-and diglycerides (polyoxyethylene (20) mono- and diglycerides of fatty acids) (polyglycerate... labeling it shall be followed by either “polyoxyethylene (20) mono-and diglycerides of fatty acids” or... (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD...

  10. 40 CFR 721.643 - Ethoxylated alcohol, phosphated, amine salt.

    Science.gov (United States)

    2010-07-01

    ... salt. 721.643 Section 721.643 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.643 Ethoxylated alcohol, phosphated, amine salt. (a) Chemical substance... alcohol, phosphated, amine salt (PMN P-96-1478) is subject to reporting under this section for the...

  11. Mechanism study on UV-induced photodegradation of nonylphenol ethoxylates by intermediate products analysis

    Institute of Scientific and Technical Information of China (English)

    Ling Chen; Hai Yun Zhou; Lan Liu; Qin Ying Deng

    2007-01-01

    Photodegradation of nonylphenol ethoxylates (NP10EO) was investigated in laboratory scale under UV irradiation. The intermediate photodegradation products were analyzed by LC-ESI-MS. Three kinds of intermediate products including aldehydic compounds, carboxylic compounds and cyclohexanyl compounds were identified. Five main degradation routes involving the oxidation of the alkyl chain and ethoxylate unit, shortening of the alkyl chain and ethoxylate unit, hydrogenation of the benzene ring were proposed.

  12. Alkyl propoxy ethoxylate "graded" surfactants: micelle formation and structure in aqueous solutions.

    Science.gov (United States)

    Sarkar, Biswajit; Alexandridis, Paschalis

    2010-04-08

    The self-assembly of alkyl propoxy ethoxylate surfactants in aqueous solutions has been investigated with a focus on the (i) thermodynamics of micellization (critical micellization concentration; free energy, enthalpy, and entropy of micellization) and (ii) structure of the micelles (overall shape and size; local environment in the micelle core and corona) as affected by the surfactant composition (variation of degree of ethoxylation). The various results are compared to those for alkyl ethoxylate and poly(ethylene oxide)-b-poly(propylene oxide) amphiphiles with the aim to elucidate the role of the middle, propoxy, block in the novel alkyl propoxy ethoxylate surfactants which exhibit a "graded" hydrophobic-hydrophilic character.

  13. 75 FR 22234 - Phosphate Ester, Tallowamine, Ethoxylated; Exemption from the Requirement of a Tolerance

    Science.gov (United States)

    2010-04-28

    ... AGENCY 40 CFR Part 180 Phosphate Ester, Tallowamine, Ethoxylated; Exemption from the Requirement of a... establishes an exemption from the requirement of a tolerance for residues of phosphate ester, tallowamine..., ethoxylated, mixture of dihydrogen phosphate and monohydrogen phosphate esters and the corresponding...

  14. Determination of dodecylbenzenesulphonates and ethoxylated alkylphenols in liquid pesticide formulations by high-performance liquid chromatography.

    Science.gov (United States)

    Schreuder, R H; Martijn, A

    1988-01-01

    A method is presented for determining mixtures of calcium dodecylbenzene-sulphonate (CaDBS) and ethoxylated alkylphenols in pesticidal emulsifiable concentrates. The pesticide formulations are adsorbed on a pre-concentration column. The active ingredients, the solvents and the emulsifiers are eluted successively by using solvents with increasing polarities. The various homologues of CaDBS and the ethoxylated alkylphenols are separated by reversed-phase high performance liquid chromatography using methanol-water containing tetramethylammonium bromide. The oligomers of the ethoxylated phenols are separated on an aminopropyl-modified column using a solvent gradient (propan-2-ol-water and hexane-tetrahydrofuran). Quantitative results are given for synthetic samples. The degree of ethoxylation of the ethoxylated alkylphenols has been determined and the CaDBS components characterized.

  15. Sodium dodecyl sulfate-ethoxylated polyethylenimine adsorption at the air-water interface: how the nature of ethoxylation affects the pattern of adsorption.

    Science.gov (United States)

    Batchelor, Stephen N; Tucker, Ian; Petkov, Jordan T; Penfold, Jeffrey; Thomas, Robert K

    2014-08-19

    The strong interaction between ionic surfactants and polyelectrolytes of opposite charge results in enhanced surface adsorption at the air-water interface down to low surfactant concentrations and in some cases in the formation of ordered surface structures. A notable example which exhibits such properties is the mixture of polyethylenimine, PEI, and sodium dodecyl sulfate, SDS. However, the electrostatic interaction, around charge neutralization, between the surfactant and polymer often results in precipitation or coacervation. This can be mitigated for PEI-surfactant mixtures by ethoxylation of the PEI, but this can also result in a weaker surface interaction and a significant reduction in the adsorption. It is shown here that by localizing the ethoxylation of the PEI into discrete regions of the polymer precipitation upon the addition of SDS is suppressed, the strong surface interaction and enhanced adsorption of the polymer-surfactant mixture is retained. The adsorption of SDS in the presence of ethoxylated PEI is greatly enhanced at low SDS concentrations compared to the adsorption for pure SDS. The adsorption is equally pronounced at pH 7 and 10 and is largely independent of the degree of ethoxylation. Surface ordering, more than monolayer adsorption, is observed over a relatively narrow range of SDS concentrations and is most pronounced at pH 10 and for the polymers with the lower degree of ethoxylation. The results show that ethoxylated PEI's reported here provide a suitable route to enhanced surfactant adsorption while retaining favorable solution properties in which precipitation effects are minimized.

  16. Comparative toxicity of nonylphenol, nonylphenol-4-ethoxylate and nonylphenol-10-ethoxylate to wheat seedlings (Triticum aestivum L.).

    Science.gov (United States)

    Zhang, Qingming; Wang, Feifei; Xue, Changhui; Wang, Caixia; Chi, Shengqi; Zhang, Jianfeng

    2016-09-01

    Nonylphenol polyethoxylates (NPEOs) are a group of surfactants that are widely used in industrial and household products and often detected in the environment. The metabolite of NPEOs, named nonylphenol (NP), has proven to be an endocrine disruptor, and its environmental behavior and eco-toxicity have been widely investigated in previous studies. However, to the best of our knowledge, insight into the toxicity differences of NP and NPEOs on important crops remains limited. Therefore, this study investigated the comparative toxicity of NP, nonylphenol-4-ethoxylate (NP4EO), and nonylphenol-10-ethoxylate (NP10EO) on wheat seedlings using hydroponic experiments. The results indicated that NP is most toxic to wheat followed by NP4EO, and NP10EO is the least toxic to wheat. The adverse effects of NP on wheat were observed for all the tested parameters including germination, shoot length, root length, chlorophyll, lipid peroxidation, and enzymatic activities. To gain insight into the molecular response, we analyzed the transcript abundance of SOD-Cu/Zn and CAT with NP, NP4EO, and NP10EO exposure using quantitative real-time PCR. The data revealed that both genes exhibited up- or down-regulated expression patterns that were consistent with the activities of the two enzymes. This result further conformed that NP is most toxic to wheat plants.

  17. The Effect of Liquid Crystalline Structures on Antiseizure Properties of Aqueous Solutions of Ethoxylated Alcohols

    OpenAIRE

    2010-01-01

    Aqueous solutions of ethoxylated alcohols which form lyotropic liquid crystals at high concentrations (40–80%) were selected as model lubricating substances. Microscopic studies under polarized light and viscosity measurements were carried out in order to confirm the presence of liquid crystalline structures in the case of alcohol solutions with ethoxylation degrees of 3, 5, 7 and 10. Microscopic images and viscosity coefficient values characteristic of various mesophases were obtained. As ex...

  18. Parallel pathways of ethoxylated alcohol biodegradation under aerobic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Zembrzuska, Joanna, E-mail: Joanna.Zembrzuska@put.poznan.pl; Budnik, Irena, E-mail: Irena.Budnik@gmail.com; Lukaszewski, Zenon, E-mail: zenon.lukaszewski@put.poznan.pl

    2016-07-01

    Non-ionic surfactants (NS) are a major component of the surfactant flux discharged into surface water, and alcohol ethoxylates (AE) are the major component of this flux. Therefore, biodegradation pathways of AE deserve more thorough investigation. The aim of this work was to investigate the stages of biodegradation of homogeneous oxyethylated dodecanol C{sub 12}E{sub 9} having 9 oxyethylene subunits, under aerobic conditions. Enterobacter strain Z3 bacteria were chosen as biodegrading organisms under conditions with C{sub 12}E{sub 9} as the sole source of organic carbon. Bacterial consortia of river water were used in a parallel test as an inoculum for comparison. The LC-MS technique was used to identify the products of biodegradation. Liquid-liquid extraction with ethyl acetate was selected for the isolation of C{sub 12}E{sub 9} and metabolites from the biodegradation broth. The LC-MS/MS technique operating in the multiple reaction monitoring (MRM) mode was used for quantitative determination of C{sub 12}E{sub 9}, C{sub 12}E{sub 8}, C{sub 12}E{sub 7} and C{sub 12}E{sub 6}. Apart from the substrate, the homologues C{sub 12}E{sub 8}, C{sub 12}E{sub 7} and C{sub 12}E{sub 6}, being metabolites of C{sub 12}E{sub 9} biodegradation by shortening of the oxyethylene chain, as well as intermediate metabolites having a carboxyl end group in the oxyethylene chain (C{sub 12}E{sub 8}COOH, C{sub 12}E{sub 7}COOH, C{sub 12}E{sub 6}COOH and C{sub 12}E{sub 5}COOH), were identified. Poly(ethylene glycols) (E) having 9, 8 and 7 oxyethylene subunits were also identified, indicating parallel central fission of C{sub 12}E{sub 9} and its metabolites. Similar results were obtained with river water as inoculum. It is concluded that AE, under aerobic conditions, are biodegraded via two parallel pathways: by central fission with the formation of PEG, and by Ω-oxidation of the oxyethylene chain with the formation of carboxylated AE and subsequent shortening of the oxyethylene chain by a

  19. Degradation pathways of low-ethoxylated nonylphenols by isolated bacteria using an improved method.

    Science.gov (United States)

    Zhang, Yu; Gu, Xin; Zhang, Jing; Yang, Min

    2014-01-01

    Nonylphenol ethoxylates (NPEOs) with low ethoxylation degree (NPav₂EO; containing two ethoxy units on average) and estrogenic properties are the intermediate products of nonionic surfactant NPEOs. To better understand the environmental fate of low-ethoxylated NPEOs, phylogenetically diverse low-ethoxylated NPEO-degrading bacteria were isolated from activated sludge using gellan gum as the gelling reagent. Four isolates belonging to four genera, i.e., Pseudomonas sp. NP522b in γ-Proteobacteria, Variovorax sp. NP427b and Ralstonia sp. NP47a in β-Proteobacteria, and Sphingomonas sp. NP42a in α-Proteobacteria were acquired. Ralstonia sp. NP47a or Sphingomonas sp. NP42a, have not been reported for the degradation of low-ethoxylated NPEOs previously. The biotransformation pathways of these isolates were investigated. The first three strains (NP522b, NP427b, and NP47a) exhibited high NPav₂EO oxidation ability by oxidizing the polyethoxy (EO) chain to form low-ethoxylated nonylphenoxy carboxylates, and then further oxidizing the alkyl chain to form carboxyalkylphenol polyethoxycarboxylates. Furthermore, Sphingomonas sp. NP42a degraded NPav2EO through a nonoxidative pathway with nonylphenol monoethoxylate as the dominant product.

  20. The Effect of Liquid Crystalline Structures on Antiseizure Properties of Aqueous Solutions of Ethoxylated Alcohols

    Directory of Open Access Journals (Sweden)

    Anna Bak

    2010-01-01

    Full Text Available Aqueous solutions of ethoxylated alcohols which form lyotropic liquid crystals at high concentrations (40–80% were selected as model lubricating substances. Microscopic studies under polarized light and viscosity measurements were carried out in order to confirm the presence of liquid crystalline structures in the case of alcohol solutions with ethoxylation degrees of 3, 5, 7 and 10. Microscopic images and viscosity coefficient values characteristic of various mesophases were obtained. As expected, the viscosity of LLCs decreases considerably with an increase in shearing rate which is characteristic of liquid crystals being non-Newtonian liquids. Antiseizure properties were determined by means of a four-ball machine (T-02 Tester and characterized by scuffing load (Pt, seizure load (Poz and limiting pressure of seizure (poz. Alcohol ethoxylates forming mesophases in aqueous solutions have the strongest effect on the Pt values which are several times higher than those measured in the presence of water. Ethoxylates with higher degrees of ethoxylation exhibit higher values of scuffing load. Those changes have been interpreted as a result of higher cloud points at which those compounds lose their amphiphilic properties. In general, the presence of mesophases in the bulk phase and particularly in the surface phase may lead to the formation of a lubricant film which separates the frictionally cooperating elements of a friction pair. The antiseizure efficiency of alcohol solutions is highest up to the load value which does not exceed the scuffing load value.

  1. The effect of liquid crystalline structures on antiseizure properties of aqueous solutions of ethoxylated alcohols.

    Science.gov (United States)

    Sulek, Marian Wlodzimierz; Bak, Anna

    2010-01-12

    Aqueous solutions of ethoxylated alcohols which form lyotropic liquid crystals at high concentrations (40-80%) were selected as model lubricating substances. Microscopic studies under polarized light and viscosity measurements were carried out in order to confirm the presence of liquid crystalline structures in the case of alcohol solutions with ethoxylation degrees of 3, 5, 7 and 10. Microscopic images and viscosity coefficient values characteristic of various mesophases were obtained. As expected, the viscosity of LLCs decreases considerably with an increase in shearing rate which is characteristic of liquid crystals being non-Newtonian liquids. Antiseizure properties were determined by means of a four-ball machine (T-02 Tester) and characterized by scuffing load (P(t)), seizure load (P(oz)) and limiting pressure of seizure (p(oz)). Alcohol ethoxylates forming mesophases in aqueous solutions have the strongest effect on the P(t) values which are several times higher than those measured in the presence of water. Ethoxylates with higher degrees of ethoxylation exhibit higher values of scuffing load. Those changes have been interpreted as a result of higher cloud points at which those compounds lose their amphiphilic properties. In general, the presence of mesophases in the bulk phase and particularly in the surface phase may lead to the formation of a lubricant film which separates the frictionally cooperating elements of a friction pair. The antiseizure efficiency of alcohol solutions is highest up to the load value which does not exceed the scuffing load value.

  2. Oxidation of ethoxylated fatty alcohols to alkylpolyglycol carboxylic acids using noble metals as catalysts

    Directory of Open Access Journals (Sweden)

    Sagredos, Angelos

    2009-09-01

    Full Text Available The conversion of ethoxylated fatty alcohols to the corresponding carboxylic acids through dehydrogenation/ oxidation using noble-metal catalysts has been studied. Ethoxylated primary aliphatic alcohols, ethoxylated random secondary aliphatic alcohols and ethoxylated alkylphenols have been converted to the corresponding acids in the presence of a base. The noble metal catalysts Palladium and Platinum were used without significant degradation of the ethoxyl chain in yields that exceeded 90%. On the other hand, the catalysts Rhodium and Ruthenium gave yields of about 80% and 60% respectively.La conversión de alcoholes grasos etoxilados a los correspondientes ácidos carboxílicos por deshidrogenación/ oxidación con metales nobles como catalizador ha sido estudiada. Alcoholes primarios alifáticos etoxilados, alcoholes alifáticos secundarios etoxilados al azar y alquilfenoles etoxilados han sido convertidos a los correspondientes ácidos en presencia de base. Los catalizadores paladio y platino fueron usados sin degradación significativa de las cadenas etoxiladas con un rendimiento que excedió del 90%. Por otra parte catalizadores de rodio y rutenio produjeron rendimientos del 80 y 60%, respectivamente.

  3. Colloidal particles derived from a complex of phosphotungstic Acid and ethoxylated surfactants.

    Science.gov (United States)

    Sweeney, Maura A; Smith, Thomas W; Croucher, Melvin; Langner, Andreas; Miri, Massoud; Klymachyov, Alex; Kaplan, Sam; Tshudy, Dwight

    2002-09-01

    Stable, colloidal sols of submicron size were prepared by titration of aqueous solutions of alkylene oxide surfactants with phosphotungstic acid, H(3)PW(12)O(40) (PTA), followed by neutralization with ammonium or potassium hydroxide. The stoichiometry of the complex between phosphotungstic acid and the ethoxylated surfactant was determined by (1)H and (31)P NMR and was dependent upon the degree of ethoxylation. For example, in the ethoxylated octylphenol having 9-10 ethylene oxide units, Triton X-100, the mole ratio of surfactant to PTA was 4.5. In the ethoxylated octylphenol having 70 ethylene oxide units, Triton X-705, the mole ratio of surfactant to PTA was 1. Prior to nucleation of particles, phosphotungstic acid forms an apparent yellow charge transfer complex with ethoxylated alkylphenol surfactants, typified by Triton X-405. This complex is characterized by an absorption spectrum that is the sum of the spectra of Triton X-405 and PTA with a very weak shoulder at 400-500 nm. Particles were nearly monodisperse and their size was dependent on the nonionic surfactant employed, the heteropolyacid, and the rate of addition of heteropolyacid solution.

  4. 40 CFR 721.6477 - Alkyl polycarboxylic acids, esters with ethoxylated fatty alcohols, reaction products with maleic...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkyl polycarboxylic acids, esters... Alkyl polycarboxylic acids, esters with ethoxylated fatty alcohols, reaction products with maleic... identified generically as alkyl polycarboxylic acids, esters with ethoxylated fatty alcohols, reaction...

  5. Degradation behaviors of nonylphenol ethoxylates by isolated bacteria using improved isolation method

    Institute of Scientific and Technical Information of China (English)

    GU Xin; ZHANG Yu; ZHANG Jing; YANG Min; Hideyuki Tamaki; Yoichi Kamagata

    2008-01-01

    Nonylphenol ethoxylate (NPEO)-degrading bacteria were isolated from activated sludge using an improved isolation method, and the corresponding degradation behaviours were investigated. Eight NPEO-degrading strains distributed in genera Pseudomonas, Sphingomonas, Sphingobium, Cupriavidus, Ralstonia, Achromobacter, and Staphylococcus were acquired. The latter five genera have never been reported for the degradation of NPEOs. Four degradation patterns were observed for the eight pure strains. In pattern A, NPEOs were converted to short-chain NPEOs and carboxylated products, while in pattern B, lower ethoxylated oligomers appeared. Nonylphenol monoethoxylate was the main product in pattern C, while in pattern D ethoxylated units was oxidized but not shortened. Pattern C and D have not yet been reported.

  6. Correlation and prediction of environmental properties of alcohol ethoxylate surfactants using the UNIFAC method

    DEFF Research Database (Denmark)

    Cheng, Hongyuan; Kontogeorgis, Georgios; Stenby, Erling Halfdan

    2005-01-01

    Environmental properties of one type of nonionic surfactants, the alcohol ethoxylates (polyoxyethylene alcohols), are predicted using the UNIFAC (universal quasi-chemical functional group activity coefficient) method. Various properties are considered; the octanol-water partition coefficient (Kow......), the bioconcentration factor (BCF), and the toxicity. Kow values of alcohol ethoxylates are difficult to measure. Existing methods such as those in commercial software like ACD,ClogP and KowWin have not been applied to surfactants, and they fail for heavy alcohol ethoxylates (alkyl carbon numbers above 12). Thus......, the Kow values are predicted here via UNIFAC and compared to the few available experimental data. Based on the predicted Kow values, a correlation between Kow and hydrophilic-lipophilic balance (HLB) is establi2shed because HLB is a widely used parameter in surfactant applications. Finally, BCF...

  7. Experimental study on oxidative decomposition of nitrobenzene in aqueous solution by honeycomb ceramic-catalyzed ozonation

    Institute of Scientific and Technical Information of China (English)

    Lei ZHAO; Jun MA; Zhizhong SUN; Zhengqian LIU; Yixin YANG

    2008-01-01

    The ozonation of nitrobenzene in aqueous solu-tion was carried out in a semi-batch reactor to investigate the degradation efficiency, the effect factors, and the reaction mechanism, where honeycomb ceramic was used as a cata-lyst. The presence of honeycomb ceramic could improve the degradation rate of nitrobenzene by 15.46% compared to the results ofozonation alone. Under the conditions of this exper-iment, the degradation rate of honeycomb ceramic-catalyzed ozonation increased by 12.94% with the increase of the amount of catalyst from 1 to 5 blocks. The degradation rates all increased greatly with the increase of temperature and pH of the solution in the processes of honeycomb ceramic-catalyzed ozonation and ozonation alone. But, when the pH of the solution increased to 9.50, the advantage of the honey-comb ceramic-catalyzed ozonation process would be lost. The experimental findings indicated that in the processes of ozonation alone and honeycomb ceramic-catalyzed ozona-tion, nitrobenzene was primarily oxidized by·OH free radical in aqueous solution. The adsorption of nitrobenzene was too limited to have an important influence on the degradation rate of nitrobenzene. With the same total dosage of applied ozone, the multiple step addition of ozone showed much higher removal efficiency than that obtained by one step in the two processes.

  8. 75 FR 74628 - Tristyrylphenol Ethoxylates; Exemption From the Requirement of a Tolerance

    Science.gov (United States)

    2010-12-01

    ... share a close structural similarity and same functional groups with the only difference being in the..., the Agency applied a correction factor of 3x to the citrus crop group to account for the potentially... tristyrylphenol ethoxylate, a conservative drinking water concentration value of 100 ppb based on screening level...

  9. 40 CFR 721.6475 - Alkyl polycarboxylic acids, esters with ethoxylated fatty alcohols.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkyl polycarboxylic acids, esters... Significant New Uses for Specific Chemical Substances § 721.6475 Alkyl polycarboxylic acids, esters with... chemical substances identified generically as alkyl polycarboxylic acids, esters with ethoxylated fatty...

  10. SEPARATION OF T-MAZ ETHOXYLATED SORBITAN FATTY ACID ESTERS BY SUPERCRITICAL FLUID CHROMATOGRAPHY

    Science.gov (United States)

    The application of supercritical fluid chromatography (SFC) to the analysis of T-MAZ ethoxylated sorbitan fatty acid esters is described. FC separation methods utilize a density programming technique and a 50 um I.D. capillary column. his work demonstrates that capillary column S...

  11. DIRECT ETHOXYLATION OF GLYCEROL MONO OLEATE FROM PALM OIL DERIVATE AS A NOVEL NON-IONIC POLYMERIC SURFACTANT

    OpenAIRE

    2012-01-01

    The work investigates ethoxylation of glycerol mono oleate (GMO) performed in the presence of an alkaline catalyst. Glycerol mono oleate applied was derivated from Indonesian palm oil. The reaction was conducted with variation of Glycerol mono oleate : ethylene oxide ratio, temperature, and catalyst concentration. Forier Transform Infra Red (FTIR) and Nuclear Magnetic Resonance (NMR) analysis showed products with degrees of ethoxylation n=2 and n=3. FTIR analysis of products gave a new peak a...

  12. Isothermal Kinetics of Catalyzed Air Oxidation of Diesel Soot

    Directory of Open Access Journals (Sweden)

    R. Prasad

    2011-01-01

    Full Text Available To comply with the stringent emission regulations on soot, diesel vehicles manufacturers more and more commonly use diesel particulate filters (DPF. These systems need to be regenerated periodically by burning soot that has been accumulated during the loading of the DPF. Design of the DPF requires rate of soot oxidation. This paper describes the kinetics of catalytic oxidation of diesel soot with air under isothermal conditions. Kinetics data were collected in a specially designed mini-semi-batch reactor. Under the high air flow rate assuming pseudo first order reaction the activation energy of soot oxidation was found to be, Ea = 160 kJ/ mol. ©2010 BCREC UNDIP. All rights reserved(Received: 14th June 2010, Revised: 18th July 2010, Accepted: 9th August 2010[How to Cite: R. Prasad, V.R. Bella. (2010. Isothermal Kinetics of Catalyzed Air Oxidation of Diesel Soot. Bulletin of Chemical Reaction Engineering and Catalysis, 5(2: 95-101. doi:10.9767/bcrec.5.2.796.95-101][DOI:http://dx.doi.org/10.9767/bcrec.5.2.796.95-101 || or local:  http://ejournal.undip.ac.id/index.php/bcrec/article/view/796]Cited by in: ACS 1 |

  13. Synthesis and physiological toxicity test of soybean oil ethoxylate%大豆油乙氧基化物的合成及其生理毒性测试

    Institute of Scientific and Technical Information of China (English)

    郭建国; 孙永强; 史修启

    2012-01-01

    The natural soybean oil ethoxylate was synthesized through one step technology-ester group insertion, and physiological toxicity of the product was tested. The results showed that soybean ethoxylates with different EO numbers were obtained through one step insertion reaction catalyzed by MCT-09. The physiological toxicity tests indicated that among non-ionic surfactants, this product was the mildest one and considered to be a kind of green surfactant. The structure of the product was tested by YT-IR.%以天然大豆油为原料,采用酯基插入式乙氧基化技术一步法合成了天然大豆油乙氧基化物,并对产品生理毒性进行了测试。结果表明,在催化剂MCT-09作用下,大豆油与环氧乙烷可顺利合成不同EO数的大豆油乙氧基化物,与其他类型非离子表面活性剂相比,天然大豆油乙氧基化物生理毒性最小,为无毒类绿色表面活性剂,并通过红外光谱对产物进行了结构鉴定。

  14. Low Temperature Aqueous Solution-Processed ZnO and Polyethylenimine Ethoxylated Cathode Buffer Bilayer for High Performance Flexible Inverted Organic Solar Cells

    National Research Council Canada - National Science Library

    Hailong You; Junchi Zhang; Zeyulin Zhang; Chunfu Zhang; Zhenhua Lin; Jingjing Chang; Genquan Han; Jincheng Zhang; Gang Lu; Yue Hao

    2017-01-01

    High performance flexible inverted organic solar cells (OSCs) employing the low temperature cathode buffer bilayer combining the aqueous solution-processed ZnO and polyethylenimine ethoxylated (PEIE...

  15. Oxidation of polyvinylpyrrolidone and an ethoxylate surfactant in phase-inversion wastewater.

    Science.gov (United States)

    Loraine, Gregory A

    2008-04-01

    In this paper, components of an industrial wastewater that cause operational problems during biological treatment were oxidized by UV light and hydrogen peroxide (UV/H202). Preoxidation of wastewater was shown to remove polyvinylpyrrolidone (PVP) and ethoxylate surfactant and increase overall biodegradability. Several UV intensities and hydrogen peroxide concentrations were tested to find optimal conditions for the complete depolymerization of PVP in a synthetic wastewater composed of high concentrations of hydroxyl radical scavengers. To compare treatment options, absorption isotherms for PVP on granular activated carbon (GAC) in water and in the synthetic phase-inversion wastewater matrix were determined. The data were extrapolated to estimate the cost of using UV/H2O2, GAC, or off-site treatment. It was found that UV/H2O2 pretreatment was economically viable. Incomplete oxidation of an ethoxylate surfactant increased foaming tendency and foam stability; however, extended oxidation (> 90 minutes) destroyed the foam.

  16. Predicting the sorption of fatty alcohols and alcohol ethoxylates to effluent and receiving water solids.

    Science.gov (United States)

    van Compernolle, R; McAvoy, D C; Sherren, A; Wind, T; Cano, M L; Belanger, S E; Dorn, P B; Kerr, K M

    2006-05-01

    Alcohol ethoxylates (AEs) are an important group of nonionic surfactants. Commercial AEs consist of a mixture of several homologues of varying carbon chain length (Cx) and degree of ethoxylation (EOy). The major disposal route of AE is down the drain to municipal wastewater treatment plants that discharge into receiving surface waters. Sorption of AE homologues onto activated sludge and river water solids is an important factor in assessing exposure of AE in the environment. This study presents the experimental determination of sorption coefficients for a wide array of AE homologues including five alcohols under environmentally relevant conditions and combines these data with literature data to generate a predictive model for the sorption of AEs in the environment. These results demonstrate that sorption can be effectively modeled using a log Kd vs. Cx and EOy predictive equation having the form log Kd = 0.331C - 0.00897EO - 1.126(R2 = 0.64).

  17. Detailed molecular characterization of castor oil ethoxylates by liquid chromatography multistage mass spectrometry.

    Science.gov (United States)

    Nasioudis, Andreas; van Velde, Jan W; Heeren, Ron M A; van den Brink, Oscar F

    2011-10-07

    The molecular characterization of castor oil ethoxylates (CASEOs) was studied by reverse-phase liquid chromatography (RPLC) mass spectrometry (MS) and multistage mass spectrometry (MS(n)). The developed RPLC method allowed the separation of the various CASEO components, and especially, the baseline separation of multiple nominal isobars (same nominal mass) and isomers (same exact mass). MS and MS(n) were used for the determination and structure elucidation of various structures and for the discrimination of the isobars and isomers. Different ionization techniques and adduct ions were also tested for optimization of the MS detection and the MS(n) fragmentation. A unique fragmentation pathway of ricinoleic acid is proposed, which can be used as a marker of the polymerization process and the topology of ethoxylation in the CASEO. In addition, characteristic neutral losses of ricinoleic acid reveal its (terminal or internal) position in the molecule.

  18. A novel application of horseradish peroxidase: Oxidation of alcohol ethoxylate to alkylether carboxylic acid

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A novel application of horseradish peroxidase (HRP) in the oxidation of alcohol ethoxylate to alkylether carboxylie acid in the present of H2O2 was reported in this paper. We propose the mechanism for the catalytic oxidation reaction is that the hydrogen transfers from the substrate to the ferryl oxygen to form the a-hydroxy carbon radical intermediate. The reaction offers a new approach for further research structure and catalytic mechanism of HRP and production of alkylether carboxylic acid.

  19. Comparison of Typical Ethoxylation Processes%典型乙氧基化工艺对比

    Institute of Scientific and Technical Information of China (English)

    刘晓东; 尤成宏; 李宁; 吴华远; 李元明; 马国权

    2013-01-01

    Ethoxylation reaction is the most important process for producing non-ionic surface active agent. Ethoxylate can be obtained by the reaction between ethylene oxide (EO) and organic compounds containing active hydrogen in the presence of the catalyst. In the field of ethoxylation, beginning from the first stirring tank reactor, reactor safety, product diversity and selectivity force designers to continuously improve design to make all kinds of new reactors. In this paper, typical ethoxylation reactors and processes at home and abroad were mainly analyzed, and their respective characteristics were discussed.%  乙氧基化反应是生产非离子表面活性剂最重要的技术,乙氧基化物由环氧乙烷(EO)在催化剂的作用下与含活泼氢的有机化合物反应制得。在乙氧基化领域,从起初的搅拌釜式反应器开始,反应器安全性、产品多样性及可选择性等方面的要求迫使设计师们不断改进设计,使得各种各样的新式反应器不断涌现,本文主要对目前国际国内典型乙氧基化反应器及工艺技术进行对比分析,指出各自所具有的特点

  20. Micellization of alkyl-propoxy-ethoxylate surfactants in water-polar organic solvent mixtures.

    Science.gov (United States)

    Sarkar, Biswajit; Lam, Stephanie; Alexandridis, Paschalis

    2010-07-06

    The effects of cosolvents (glycerol, ethanol, and isopropanol) on the self-assembly of novel alkyl-propoxy-ethoxylate surfactants in aqueous solutions have been investigated with a focus on the (i) quantification of solvent effects on the critical micelle concentration (cmc), (ii) free-energy contributions to micellization, (iii) local environment in the micellar solution, and (iv) structure of the micelles. The introduction of the polar organic solvents considered in this work into water decreases cohesive forces in the solvent mixture, resulting in an increase in the solubility of the surfactant molecules. As a result, micelle formation becomes less favorable and the cmc increases. The contribution of the cosolvent to the free energy of micellization is positive, and the data for different mixed solvents collapse onto a single straight line when plotted versus a function of the solubility parameters of the surfactant alkyl chains and the mixed solvents. The behavior of the poly(propylene oxide) part of the alkyl-propoxy-ethoxylate surfactants is hydrophilic, albeit less so in the ethanol-water mixed solvent than in plain water. Pyrene fluorescence emission I(1)/I(3) data suggest that the microenvironment in micellar solutions is affected mainly by the cosolvent concentration, not the surfactant degree of ethoxylation. Small-angle X-ray scattering data for both water and ethanol-water surfactant solutions are consistent with oblate ellipsoid micelles and reveal that the introduction of 20% ethanol decreases the micelle long axis by 10-15%.

  1. Cobalt catalyzed hydroesterification of a wide range of olefins

    Energy Technology Data Exchange (ETDEWEB)

    Van Rensburg, H.; Hanton, M.; Tooze, R.P.; Foster, D.F. [Sasol Technology UK, St Andrews (United Kingdom)

    2011-07-01

    Petrochemical raw materials are an essential raw material for the production of detergents with a substantial portion of synthetic fatty alcohols being produced via hydroformylation of oil or coal derived olefins. Carbonylation processes other than hydroformylation have to date not been commercially employed for the production of fatty esters or alcohols. In this document we highlight the opportunities of converting olefins to esters using cobalt catalyzed alkoxycarbonylation. This process is highly versatile and applicable to a wide range of olefins, linear or branched, alpha or internal in combination with virtually any chain length primary or secondary alcohol allowing the synthesis of a diverse array of compounds such as ester ethoxylated surfactants, methyl branched detergents, lubricants and alkyl propanoates. Furthermore, alkoxycarbonylation of a broad olefin/paraffin hydrocarbon range could be used to produce the corresponding broad cut detergent alcohols. (orig.)

  2. Spontaneous surface self-assembly in protein-surfactant mixtures: interactions between hydrophobin and ethoxylated polysorbate surfactants.

    Science.gov (United States)

    Tucker, Ian M; Petkov, Jordan T; Penfold, Jeffrey; Thomas, Robert K; Li, Peixun; Cox, Andrew R; Hedges, Nick; Webster, John R P

    2014-05-01

    The synergistic interactions between certain ethoxylated polysorbate nonionic surfactants and the protein hydrophobin result in spontaneous self-assembly at the air-water interface to form layered surface structures. The surface structures are characterized using neutron reflectivity. The formation of the layered surface structures is promoted by the hydrophobic interaction between the polysorbate alkyl chain and the hydrophobic patch on the surface of the globular hydrophobin and the interaction between the ethoxylated sorbitan headgroup and hydrophilic regions of the protein. The range of the ethoxylated polysorbate concentrations over which the surface ordering occurs is a maximum for the more hydrophobic surfactant polyoxyethylene(8) sorbitan monostearate. The structures at the air-water interface are accompanied by a profound change in the wetting properties of the solution on hydrophobic substrates. In the absence of the polysorbate surfactant, hydrophobin wets a hydrophobic surface, whereas the hydrophobin/ethoxylated polysorbate mixtures where multilayer formation occurs result in a significant dewetting of hydrophobic surfaces. The spontaneous surface self-assembly for hydrophobin/ethoxylated polysorbate surfactant mixtures and the changes in surface wetting properties provide a different insight into protein-surfactant interactions and potential for manipulating surface and interfacial properties and protein surface behavior.

  3. DIRECT ETHOXYLATION OF GLYCEROL MONO OLEATE FROM PALM OIL DERIVATE AS A NOVEL NON-IONIC POLYMERIC SURFACTANT

    Directory of Open Access Journals (Sweden)

    Joddy Arya Laksmono

    2012-01-01

    Full Text Available The work investigates ethoxylation of glycerol mono oleate (GMO performed in the presence of an alkaline catalyst. Glycerol mono oleate applied was derivated from Indonesian palm oil. The reaction was conducted with variation of Glycerol mono oleate : ethylene oxide ratio, temperature, and catalyst concentration. Forier Transform Infra Red (FTIR and Nuclear Magnetic Resonance (NMR analysis showed products with degrees of ethoxylation n=2 and n=3. FTIR analysis of products gave a new peak at 1570 cm-1 supporting that C-O-C bond was formed. New peaks were also observed in 13-C-NMR analysis of run 2 and run 3 with chemical shift of (δ 61.3385; 61.9108; 62.5117; 63.8566; 66.0982; 72.6127 and 61.2172; 63.2393; 65.9100; 72.5201, respectively. Glycerol mono oleate ethoxylated was yielded and could be useful for a novel non-ionic polymeric surfactant.

  4. New hydrophilic interaction/reversed-phase mixed-mode stationary phase and its application for analysis of nonionic ethoxylated surfactants.

    Science.gov (United States)

    Liu, Xiaodong; Pohl, Christopher

    2008-05-16

    We have developed a new stationary phase that combines both hydrophilic interaction and reversed-phase characteristics. The new phase is based on high-purity, porous and spherical silica gel functionalized with a silyl ligand consisting of both hydrophilic and hydrophobic functionalities. This phase can be operated in both HILIC mode (high organic solvent) and RPLC mode (low organic solvent). An optimal balance of hydrophilic and hydrophobic moieties on the silica surface provides unique chromatographic properties that make it useful for determination of alkyl chain distribution and degree of ethoxylation (EO number) of nonionic ethoxylated surfactants.

  5. Study of adjuvant effect of model surfactants from the groups of alkyl sulfates, alkylbenzene sulfonates, alcohol ethoxylates and soaps

    DEFF Research Database (Denmark)

    Clausen, S K; Sobhani, S; Poulsen, O M

    2000-01-01

    The sodium salts of representatives of anionic surfactants, dodecylbenzene sulfonate (SDBS), dodecyl sulfate (SDS) and coconut oil fatty acids, and a nonionic surfactant, dodecyl alcohol ethoxylate, were studied for adjuvant effect on the production of specific IgE antibodies in mice...... showed a statistically significant increase in OVA specific IgE levels. After two boosters, a statistically significant suppression in OVA-specific IgE production occurred with SDS (1000 mg/l), SDBS (1000 and 100 mg/l), coconut soap (1000 mg/l) and the alcohol ethoxylate (10 mg/l). This study suggests...

  6. Releases of selected alkylphenols and alkylphenol ethoxylates and use in consumer products

    DEFF Research Database (Denmark)

    Lassen, Carsten; Warming, Marlies; Fauser, Patrik

    EPA has initiated a survey of emissions of alkylphenols and al-kylphenol ethoxylates from all life cycle stages of the substances and a survey of the use of the sub-stances in consumer products. The main objectives of the surveys are:  to establish an overview of the releases of the AP....... The surveys have been undertaken by COWI A/S in co-operation with the National Centre for Ener-gy and Environment (DCE), Aarhus University. The project has been followed by a steering group consisting of:  Sidsel Dyekjær, Danish EPA  Carsten Lassen, COWI A/S  Patrik Fauser, DCE...

  7. Determination of free and ethoxylated alkylphenols in leather with gas chromatography-mass spectrometry.

    Science.gov (United States)

    Ma, He-Wei; Cheng, Ya

    2010-12-10

    An analytical approach was developed to determine nonylphenol (NP), octylphenol (OP), nonylphenol ethoxylates (NPEO(n)) and octylphenol ethoxylates (OPEO(n)) in leather samples involving the conversion of NPEO(n) and OPEO(n) into the corresponding NP and OP. The four targets were extracted from samples using ultrasonic-assisted acetonitrile extraction. NP and OP in the extracts were directly isolated with hexane and quantitatively determined with 4-n-nonylphenol as internal standard by gas chromatography-mass spectrometry (GC-MS). For NPEO(n) and OPEO(n) in the extracts, they were first converted into NP and OP with aluminum triiodide as cleavage agent, and the yielded NP and OP were determined by GC-MS. The contents of NPEO(n) and OPEO(n) were calculated by normalizing to NPEO(9) and OPEO(9), respectively. This method was properly validated and the real sample tests revealed the pollution significance of leather by NPEO(n) and OPEO(n).

  8. Removal and environmental exposure of alcohol ethoxylates in US sewage treatment.

    Science.gov (United States)

    Morrall, S W; Dunphy, J C; Cano, M L; Evans, A; McAvoy, D C; Price, B P; Eckhoff, W S

    2006-05-01

    Alcohol ethoxylates (AE) are a common nonionic surfactant employed in consumer and industrial detergents worldwide. Commercial AE are typically complex mixtures composed of > 100 homologous compounds with varying alkyl chain lengths and varying numbers of ethylene oxide (EO) units. Recent improvements in analytical methodology have enabled accurate measurement of the entire AE mixture in sewage treatment plant (STP) influents and effluents, including alkyl chain lengths from 12 to 18 carbons with a range of ethoxylation from 0 to 18 EO units. These improved analytical methods were used to measure AE concentrations at nine sites representative of sewage treatment processes and geographical locations. These new data will make possible a more accurate assessment of environmental risk for AE in the United States. The results indicate that all AE homologues are effectively removed (> 99%) in the most common treatment types. Individual STP total AE effluent concentrations ranged from a low of 0.92 microg/L for activated sludge to a high of 15.6 microg/L for a trickling filter process. For the purpose of representing a national average distribution, an average-flow-weighted wastewater treatment plant effluent concentration was determined for each AE component. The total-flow-weighted average AE effluent concentration was 3.64 microg/L.

  9. Linear alcohol ethoxylates: insecticidal and synergistic effects on German cockroaches (Blattodea: Blattellidae) and other insects.

    Science.gov (United States)

    Sims, Steven R; Appel, Arthur G

    2007-06-01

    Sixteen linear ethoxylated alcohol surfactants (AEOs) were studied to determine their contact insecticidal activity to adult German cockroaches, Blattella germanica (L.) (Blattodea: Blattellidae). Within groups of AEOs of equal carbon chain length, insecticidal activity, measured as LT50 values (in minutes) and 24-h mortality after treatment, was inversely related to the amount of ethoxylation. There was a highly significant negative relationship between the hydrophile-lipophile balance (HLB) value of the AEO and contact toxicity. The AEO with the lowest HLB value, Tomadol 23-1 (HLB = 3.7), produced the greatest 24-h cockroach mortality. The contact activity of Tomadol 23-1 was evaluated against a wide range of other insect species. Most species were killed within 24 h by direct exposure (1-4 microl of a 50% ethanol solution) to Tomadol 23-1 or by spray exposure to an aqueous solution. Tomadol 23-1, at a sublethal concentration, was tested in combination with representative members of the carbamate, nicotinoid, organophosphate, pyrethrum, pyrethroid, and pyrrole insecticide classes. Significant synergism was demonstrated in combinations of Tomadol 23-1 and chlorfenapyr, clothianidin, imidacloprid, thiamethoxam, and pyrethrum. Tomadol 23-1 significantly reduced the insecticidal activity of propoxur, suggesting antagonism. The insecticidal activity of Tomadol 23-1 was synergized by coapplication with a sublethal amount of piperonyl butoxide, indicating the involvement of cytochrome P450 microsomal monooxygenases in insect metabolism of AEO surfactants.

  10. A comparison of alcohol ethoxylate environmental monitoring data using different analytical procedures.

    Science.gov (United States)

    McAvoy, Drew C; Eckhoff, William S; Begley, William M; Pessler, Daniel G

    2006-05-01

    Several analytical methods have been developed for analyzing alcohol ethoxylates (AE) in aqueous environmental samples. These methods differ widely in their selectivity and sensitivity for measuring the AE components; that is, they vary in their resolution of alkyl chain length homologs and ethoxymer distributions (degree of ethoxylation for each homolog). Given these differences, AE monitoring results from different studies often are inconsistent and, sometimes, are deemed to be incomparable. To address these differences, three currently available methods for determining AE concentrations in environmental matrices were compared among a common set of wastewater treatment plant samples. These methods included the detection of hydrogen bromide-derivatized homologs by gas chromatography/mass spectrometry, the detection of aqueous homologs by high-pressure liquid chromatography/electrospray mass spectrometry, and the detection of pyridinium-derivatized homologs by high-pressure liquid chromatography/electrospray mass spectrometry. Results from the present study showed that all three methods responded differently in determining the complex suite of chemical species that comprise AE in the environment. The collective information, however, allowed a consistent comparison among the methods. This comparison was then used to reevaluate results from previous AE monitoring studies. Results from this reevaluation provided a more realistic profile of both historical AE removal during wastewater treatment as well as the occurrence of AE in U.S. surface waters.

  11. Partitioning behavior of an acid-cleavable, 1,3-dioxolane alkyl ethoxylate, surfactant in single and binary surfactant mixtures for 2- and 3-phase microemulsion systems according to ethoxylate head group size

    Energy Technology Data Exchange (ETDEWEB)

    Gomez Del Rio, Javier A [ORNL; Hayes, Douglas G [ORNL; Urban, Volker S [ORNL

    2010-01-01

    Partition coefficients for a pH-degradable 1,3-dioxolane alkyl ethoxylate surfactant, 4-CH{sub 3}O (CH{sub 2}CH{sub 2}O){sub 5.6}-CH{sub 2}, 2,2-(CH{sub 2}){sub 12}CH{sub 3}, 2-(CH{sub 2}) CH{sub 3}, 1,3-dioxolane or ''cyclic ketal'' surfactant, CK-2,13-E{sub 5.6,ave}, between isooctane- and water-rich phases of 2- and 3-phase microemulsion systems (K{sub n}) were determined as functions of the ethoxylate size, n, and temperature for the neat surfactant and its binary surfactant mixtures, to understand the partitioning of alkyl ethoxylates possessing a broad distribution of ethoxylate size and to determine conditions required for formation of 3-phase microemulsion systems at an optimal temperature where phase separation occurs rapidly, important for protein purification via proteins selective partitioning to the middle phase, driven by affinity to the second surfactant of the binary mixture. A semi-empirical thermodynamic mathematical model described the partitioning data well, provided optimal temperature values consistent with phase diagrams and theory, and demonstrated that the tail region of CK-2,13-E{sub 5.6,ave} is more polar than the hydrophobes of fatty alcohol ethoxylates. The addition of Aerosol-OT (AOT) removed the temperature sensitivity of CK-2,13-E{sub 5.6,ave}s partitioning, producing 3-phase microemulsion systems between 20 C and 40 C. Analysis of the bottom phases of the 2- and 3-phase microemulsion systems formed by CK-2,13-E{sub 5.6,ave} via small-angle neutron scattering demonstrated the presence of spherical, monodisperse oil-in-water microemulsions.

  12. Optimization of Ethoxylation Reaction Process Conditions%乙氧基化反应工艺条件的优化

    Institute of Scientific and Technical Information of China (English)

    钱梁华; 吕海丽

    2016-01-01

    对乙氧基化反应机理及反应特点进行了研究,进而分析了催化剂、反应温度、反应压力及传质等因素对乙氧基化反应速率的影响;通过对乙氧基化反应回路换热器热量衡算,对乙氧基化反应工艺条件优化进行了探讨。结果表明:提高反应温度及压力,有利于乙氧基化反应速率的提高;采用冷却水作为换热介质,在换热量不变的情况下,冷却水的用量约为导热油用量的48%,可以起到降耗的作用。%The mechanism and characteristics of ethoxylation reaction were studied,and the effects of influencing factors such as catalyst,reaction temperature,reaction pressure and mass transfer on ethoxylation reaction rate were further analyzed.Based on the heat balance of ethoxylation reaction loop heat exchanger,the optimization of ethoxylation reaction process conditions was discussed.Results showed that increasing the reaction temperature and pressure were beneficial to the improvement of the ethoxylation reaction rate;and the amount of consumption of cooling water is approximate 48% of the conduction oil under the condition of the constant heat transfer if taking the cooling water as heat transfer medium,which could save energy and reduce consumption.

  13. Production of ethoxylated fatty acids derived from Jatropha non-edible oil as a nonionic fat-liquoring agent.

    Science.gov (United States)

    El-Shattory, Y; Abo-Elwafa, Ghada A; Aly, Saadia M; Nashy, El-Shahat H A

    2012-01-01

    Natural fatty derivatives (oleochemicals) have been used as intermediate materials in several industries replacing the harmful and expensive petrochemicals. Fatty ethoxylates are one of these natural fatty derivatives. In the present work Jatropha fatty acids were derived from the non edible Jatropha oil and used as the fat source precursor. The ethoxylation process was carried out on the derived fatty acids using a conventional cheap catalyst (K₂CO₃) in order to obtain economically and naturally valuable non-ionic surfactants. Ethoxylation reaction was proceeded using ethylene oxide gas in the presence of 1 or 2% K₂CO₃ catalyst at 120 and 145°C for 5, 8 and 12 hours. The prepared products were evaluated for their chemical and physical properties as well as its application as non- ionic fat-liquoring agents in leather industry. The obtained results showed that the number of ethylene oxide groups introduced in the fatty acids as well as their EO% increased as the temperature and time of the reaction increased. The highest ethoxylation number was obtained at 145°C for 8 hr. Also, the prepared ethoxylated products were found to be effective fat-liquors with high HLB values giving stable oil in water emulsions. The fat-liquored leather led to an improvement in its mechanical properties such as tensile strength and elongation at break. In addition, a significant enhancement in the texture of the treated leather by the prepared fat-liquors as indicated from the scanning electron microscope (SEM) images was observed.

  14. Adsorption at air-water and oil-water interfaces and self-assembly in aqueous solution of ethoxylated polysorbate nonionic surfactants.

    Science.gov (United States)

    Penfold, Jeffrey; Thomas, Robert K; Li, Peixun X; Petkov, Jordan T; Tucker, Ian; Webster, John R P; Terry, Ann E

    2015-03-17

    The Tween nonionic surfactants are ethoxylated sorbitan esters, which have 20 ethylene oxide groups attached to the sorbitan headgroup and a single alkyl chain, lauryl, palmityl, stearyl, or oleyl. They are an important class of surfactants that are extensively used in emulsion and foam stabilization and in applications associated with foods, cosmetics and pharmaceuticals. A range of ethoxylated polysorbate surfactants, with differing degrees of ethoxylation from 3 to 50 ethylene oxide groups, have been synthesized and characterized by neutron reflection, small-angle neutron scattering, and surface tension. In conjunction with different alkyl chain groups, this provides the opportunity to modify their surface properties, their self-assembly in solution, and their interaction with macromolecules, such as proteins. Adsorption at the air-water and oil-water interfaces and solution self-assembly of the range of ethoxylated polysorbate surfactants synthesized are presented and discussed.

  15. Electronic structure and mesoscopic simulations of nonylphenol ethoxylate surfactants. a combined DFT and DPD study.

    Science.gov (United States)

    Valencia, Diego; Aburto, Jorge; García-Cruz, Isidoro

    2013-08-07

    The aim of this work was to gain insight into the effect of ethylene oxide (EO) chains on the properties of a series of nonylphenol ethoxylate (NPE) surfactants. We performed a theoretical study of NPE surfactants by means of density functional theory (DFT) and dissipative particle dynamics (DPD). Both approximations were used separately to obtain different properties. Four NPEs were selected for this purpose (EO = 4, 7, 11 and 15 length chains). DFT methods provided some electronic properties that are related to the EO units. One of them is the solvation Gibbs energy, which exhibited a linear trend with EO chain length. DPD calculations allow us to observe the dynamic behavior in water of the NPE surfactants. We propose a coarse-grained model which properly simulates the mesophases of each surfactant. This model can be used in other NPEs applications.

  16. Electronic Structure and Mesoscopic Simulations of Nonylphenol Ethoxylate Surfactants. A Combined DFT and DPD Study

    Directory of Open Access Journals (Sweden)

    Isidoro García-Cruz

    2013-08-01

    Full Text Available The aim of this work was to gain insight into the effect of ethylene oxide (EO chains on the properties of a series of nonylphenol ethoxylate (NPE surfactants. We performed a theoretical study of NPE surfactants by means of density functional theory (DFT and dissipative particle dynamics (DPD. Both approximations were used separately to obtain different properties. Four NPEs were selected for this purpose (EO = 4, 7, 11 and 15 length chains. DFT methods provided some electronic properties that are related to the EO units. One of them is the solvation Gibbs energy, which exhibited a linear trend with EO chain length. DPD calculations allow us to observe the dynamic behavior in water of the NPE surfactants. We propose a coarse-grained model which properly simulates the mesophases of each surfactant. This model can be used in other NPEs applications.

  17. Anaerobic nonylphenol ethoxylate degradation coupled to nitrate reduction in a modified biodegradability batch test.

    Science.gov (United States)

    Luppi, Lorena I; Hardmeier, Ivo; Babay, Paola A; Itria, Raúl F; Erijman, Leonardo

    2007-08-01

    The aim of this work was to elucidate the role of nitrate as a terminal electron acceptor on the biodegradation of NPEO. We have characterized the products of NPEO degradation by mixed microbial communities in anaerobic batch tests by means of HPLC, (1)H NMR and GC-MS. Anaerobic degradation of NPEO was strictly dependent on the presence of nitrate. Within seven days of anoxic incubation, NP2EO appeared as the major degradation product. After 21 days, NP was the main species detected, and was not degraded further even after 35 days. Nitrate concentration decreased in parallel with NPEO de-ethoxylation. A transient accumulation of nitrite was observed within the time period in which NP formation reached its maximum production. The observed generation of nonylphenol coupled to nitrate reduction suggests that the microbial consortium possessed an alternate pathway for the degradation of NPEO, which was not accessible under aerobic conditions.

  18. Elimination and Recycling of Imatinib by Ethoxylated Multi-Walled Carbon Nanotubes from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Maryam Pakzad Masouleh

    2015-06-01

    Full Text Available An adsorbent and carrier based on ethoxylated functionalized multi-walled carbon nanotubes (f-MWCNTs were prepared with diethylene glycol (2EG followed by esterification process. Resultant dietylene glycolated MWCNTs (MWCNTs-2EG used for elimination of Imatinib mesylate (Ima from water. Maximum Ima adsorption per 3 mg of adsorbent and 9 mg of initial Ima was 8.76 mg. maximum recycling at two pH values 7.4 and 5.3 was determined about 6.15 mg (70% and 7.42 mg (85% respectively. Ima elimination and recycling process is greatly enhanced by the creation of functional groups on the MWCNTs-2EG in compare with carboxylated MWCNTs (MWCNTs-COOH.

  19. Adsorption and recovery of nonylphenol ethoxylate on a crosslinked beta-cyclodextrin-carboxymethylcellulose polymer.

    Science.gov (United States)

    Bonenfant, Danielle; Niquette, Patrick; Mimeault, Murielle; Hausler, Robert

    2010-01-01

    A study of adsorption/recovery of nonylphenol 9 mole ethoxylate (NP9EO) on a crosslinked beta-cyclodextrin-carboxymethylcellulose (beta-CD-CMC) polymer was carried out by ultraviolet-visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopies. The adsorption was performed in mixtures containing 500 mg of the beta-CD-CMC polymer and aqueous NP9EO solutions at concentrations 12-82 mg/L, whereas the recovery of NP9EO was effectuated by shaking the beta-CD-CMC polymer loaded with methanol. The assays were made at 25 degrees C and atmospheric pressure under agitation. The results have shown that the adsorption is a rapid process and the beta-CD-CMC polymer exhibits a high NP9EO adsorption capacity of 83-92 w% (1.1-6.8 mg NP9EO/g beta-CD-CMC polymer) dependent of the initial NP9EO concentration in liquid phase. This adsorption may involve the formation of an inclusion complex beta-CD-NP9EO and a physical adsorption in the polymer network. The adsorption equilibrium measurements, which were analyzed using the Langmuir isotherm, have indicated a monolayer coverage and the homogeneous distribution of active sites at the surface of the beta-CD-CMC polymer. Moreover, the negative value obtained for the free energy change (-13.2 kJ/mol) has indicated that the adsorption process is spontaneous. In parallel, the beta-CD-CMC polymer exhibited a high NP9EO recovery efficiency of 97 w% that may occur through a decrease of binding strength between beta-CD-CMC polymer and NP9EO. Together, these results suggest that the beta-CD-CMC polymer could constitute a good adsorbent for removing nonylphenol ethoxylates from wastewater due to its high adsorption capacity and non-toxic character of beta-CD and CMC to environment.

  20. The Cloud Point of Alkyl Ethoxylates and Its Prediction with the Hydrophilic-Lipophilic Difference (HLD) Framework.

    Science.gov (United States)

    Zarate-Muñoz, Silvia; Boza Troncoso, Americo; Acosta, Edgar

    2015-11-10

    The hydrophobicity of surfactants has been described through different concepts used to guide the formulation of surfactant-water (SW) and surfactant-oil-water (SOW) systems. An integrated framework of hydrophobicity indicators could provide a complete tool for surfactant characterization, and insights on how their relationship may influence the overall phase behavior of the system. The hydrophilic-lipophilic difference (HLD) and the characteristic curvature (Cc) parameter, included in the HLD, have been shown to correlate with different hydrophobicity indicators including the hydrophilic-lipophilic balance (HLB), packing factor (Pf), phase inversion temperature (PIT), spontaneous curvature (Ho), surfactant partition (K(o-w)), and the critical micelle concentration (CMC). This work aims to investigate whether the HLD can further describe a concomitant hydrophobicity parameter, the cloud point (CP) of alkyl ethoxylates. After applying group contribution models to calculate the Cc of monodisperse (pure) nonionic alkyl ethoxylates, a linear correlation between the calculated Cc and the CP was observed for pure surfactants with 8 ethylene oxide (EO) units or less. Furthermore, using an apparent equivalent alkane carbon number (EACN) to represent the hydrophobicity of the micelle core, the HLD equation was capable of predicting cloud point temperatures of pure alkyl ethoxylates, typically within 5 °C. Polydisperse surfactants did not follow the linear CP-Cc correlation found for pure surfactants. After treating polydisperse samples using a liquid-liquid extraction procedure used to remove the most hydrophobic components in the mixture, the resulting treated surfactants fell in the correlation line of pure alkyl ethoxylates. A closer look at the partition behavior of these treated surfactants showed that their partition, Cc and cloud point are dominated by the most abundant ethoxymers in the treated surfactant. The HLD also predicted the cloud point depression of

  1. Effects of nonionic surfactant lauryl alcohol ethoxylated on stratum corneum alternative model biomembranes evaluated by biophysical techniques

    OpenAIRE

    Baby, André R.; Lacerda, Áurea C. L.; Prestes, Paula S.; Velasco, María Valéria R.; Kawano, Yoshio; Kaneko,Telma Mary

    2011-01-01

    The influence of the nonionic surfactant lauryl alcohol ethoxylate with 12 moles ethylene oxide (LAE-12OE) was evaluated on the Stratum corneum model biomembrane (SCMM) of shed snake skin (Bothrops jararaca and Spilotes pullatus) through the biophysical techniques Fourier transform Raman spectroscopy (FT-Raman) and Fourier transform infrared photoacoustic spectroscopy (PAS-FTIR). The surfactant was used in aqueous solutions above and below the critical micelle concentration (cmc), 50.0 and 0....

  2. Occurrence and risk screening of alcohol ethoxylate surfactants in three U.S. river sediments associated with wastewater treatment plants.

    Science.gov (United States)

    Sanderson, Hans; van Compernolle, Remi; Dyer, Scott D; Price, Bradford B; Nielsen, Allen M; Selby, Martin; Ferrer, Darci; Stanton, Kathleen

    2013-10-01

    Alcohol ethoxylates (AE) are high production volume (HPV) chemicals globally used in detergent and personal care products and are truly a work-horse for the household and personal care industries. Commercial AE generally consist of a mixture of several homologues of varying carbon chain length and degree of ethoxylation. Homologues that are not ethoxylated are also known as aliphatic alcohols or simply fatty alcohols (FA). This group of homologues represents a special interest in the context of environmental risk, as these are also abundant and ubiquitous naturally occurring compounds (e.g. animal fats and in human feces). Hence, in a risk assessment one needs to distinguish between the natural (background) concentrations and the added contribution from anthropogenic activities. We conducted a weight-of-evidence risk assessment in three streams, documenting the exposure and predicted risk, and compared these to the habitat and in situ biota. We found that the parameters (e.g., habitat quality and total perturbations hereunder total suspended solids (TSS) and other abiotic and biotic stressors) contributed to the abundance of biota rather than the predicted risk from AE and FA. Moreover, the documented natural de novo synthesis and rapid degradation of FA highlight the need to carefully consider the procedures for environmental risk assessment of naturally occurring compounds such as FA, e.g. in line with the added risk concept known from metal risk assessment.

  3. Biodegradation of low-ethoxylated nonylphenols in a bioreactor packed with a new ceramic support (Vukopor ® S10).

    Science.gov (United States)

    Sciubba, Luigi; Bertin, Lorenzo; Todaro, Daniela; Bettini, Cristina; Fava, Fabio; Di Gioia, Diana

    2014-03-01

    This work was aimed at studying the possibility of biodegrading 4-nonylphenol and low ethoxylated nonylphenol mixtures, which are particularly recalcitrant to microbial degradation, by employing a biofilm reactor packed with a ceramic support (Vukopor® S10). A selected microbial consortium (Consortium A) was used to colonize the support. 4-Nonylphenol and ethoxylated nonylphenol degradation and mineralization capabilities were studied both in batch and continuous mode. The results showed that Vukopor® S10 was able to be colonized by an active biofilm for the degradation of the target pollutants with the reactor operating both in batch and continuous mode. On the other hand, pollutant adsorption on the support was negligible. FISH showed equal proportion of Alphaproteobacteria and Gammaproteobacteria in the Igepal CO-520 degrading reactor. A shift towards high proportion of Gammaproteobacteria was observed by supplying Igepal CO-210. PCR-density gradient gel electrophoresis (DGGE) analyses also evidenced that the biofilm evolved with time by changing the mixture applied and that Proteobacteria were the most represented phylum in the biofilm. Taken together, the data obtained provide a strong indication that the biofilm reactor packed with Vukopor® S10 and inoculated with Consortium A could potentially be used to develop a technology for the decontamination of 4-nonylphenol and low ethoxylated nonylphenol polluted effluents.

  4. Sugar-based ethoxylated amine surfactants as demulsifiers for crude oil emulsions: 2-demulsification of different types of crudes

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Azim, A.A.A.; Abdel-Raouf, M.E.S.; Abdul-Raheim, A.R.M.; Maysor, N.E.S. [Egyptian Petroleum Research Institute, Cairo (Egypt). Petroleum Application Dept.], e-mail: drmanar770@yahoo.com

    2010-10-15

    The present work studies demulsification of two types of crude oil emulsions by nine sugar-based ethoxylated amine surfactants. The effect of pH and salinity of aqueous phase of crude oil on emulsion stability was considered, and the correlation between demulsification rate and the type of crude was studied. Nine sugar-based ethoxylated amine surfactants were tested as demulsifiers for light and heavy crudes at different aqueous phase conditions. It was found that the light crude was more easily demulsified than the heavy crude. The experimental data showed that changes in pH or salinity of the aqueous phase of the emulsion enhance its stability and decrease the demulsification efficiency of the applied demulsifiers. Also, it has been shown that surfactants based on glucose octyl amine ethoxylates (GO) are the most effective in demulsifying the investigated emulsions. The data reveal that maximum demulsification efficiency is attained at a neutral pH whereas it decreases in both directions for either of the investigated crude oils. Furthermore, the results indicate that the percentage of water separation decreases as the salinity of the emulsion's aqueous phase increases. Light crudes showed better demulsification than heavy crudes under any test condition. The demulsification process for selected emulsions was monitored by optical microscopy. (author)

  5. The fate of linear alcohol ethoxylates during activated sludge sewage treatment.

    Science.gov (United States)

    Battersby, N S; Sherren, A J; Bumpus, R N; Eagle, R; Molade, I K

    2001-10-01

    Model continuous activated sludge (CAS) plants (Husmann units) were used to study the fate of two commercial, alcohol ethoxylate (AE) surfactants during aerobic sewage treatment. The surfactants were produced by the ethoxylation of an essentially linear C(12-15) alcohol (NEODOL 25) with an average of 7 (C(12-15)EO7) or 3 (C(12-15)EO3) moles of ethylene oxide (EO). Recent analytical developments made it possible to measure levels of AE that included the free alcohol and EO1 oligomers across the CAS system, from the influent feed, on the activated sludge, through to the effluent. Measured concentrations of AE (as C(12-15)EO(0-20)) in the synthetic sewage feeds to the test CAS plants lay in the range 11-13 mg/l. During stable operation at 20 degrees C, an average of 5 microg/l AE were present in the C(12-15)EO7 CAS plant effluent, giving a removal (bioelimination) of >99.9%. When levels of AE on the sludge, and polyethylene glycols (PEGs--an expected biodegradation intermediate) in the effluent and on the sludge were also taken into account, biodegradation was considered to be responsible for >98.7% of the observed removal. During operation at a winter temperature (10 degrees C), an average of 26 microg/l AE were present in the C(12-15)EO7 CAS plant effluent, giving a removal of 99.8%. Biodegradation was estimated to be responsible for >97.2% of the observed removal. During operation at 20 degrees C, an average of 7 microg/l AE were present in the C(12-15)EO3 CAS plant effluent, giving a removal of >99.9%. No analysis for PEG was performed in this case but the low level of AE on the sludge (0.2 mg/g dry solids) suggested that biodegradation was responsible for most of the observed removal. Neither surfactant had any adverse effect on the sewage treatment efficiencies of the CAS plants in terms of dissolved organic carbon (DOC) removal, nitrification or biomass levels.

  6. Muon Catalyzed Fusion

    Science.gov (United States)

    Armour, Edward A.G.

    2007-01-01

    Muon catalyzed fusion is a process in which a negatively charged muon combines with two nuclei of isotopes of hydrogen, e.g, a proton and a deuteron or a deuteron and a triton, to form a muonic molecular ion in which the binding is so tight that nuclear fusion occurs. The muon is normally released after fusion has taken place and so can catalyze further fusions. As the muon has a mean lifetime of 2.2 microseconds, this is the maximum period over which a muon can participate in this process. This article gives an outline of the history of muon catalyzed fusion from 1947, when it was first realised that such a process might occur, to the present day. It includes a description of the contribution that Drachrnan has made to the theory of muon catalyzed fusion and the influence this has had on the author's research.

  7. Catalyzing RE Project Development

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Kate; Elgqvist, Emma; Walker, Andy; Cutler, Dylan; Olis, Dan; DiOrio, Nick; Simpkins, Travis

    2016-09-01

    This poster details how screenings done with REopt - NREL's software modeling platform for energy systems integration and optimization - are helping to catalyze the development of hundreds of megawatts of renewable energy.

  8. Degradation of the commercial surfactant nonylphenol ethoxylate by advanced oxidation processes.

    Science.gov (United States)

    da Silva, Salatiel Wohlmuth; Klauck, Cláudia Regina; Siqueira, Marco Antônio; Bernardes, Andréa Moura

    2015-01-23

    Four different oxidation process, namely direct photolysis (DP) and three advanced oxidation processes (heterogeneous photocatalysis - HP, eletrochemical oxidation - EO and photo-assisted electrochemical oxidation - PEO) were applied in the treatment of wastewater containing nonylphenol ethoxylate (NPnEO). The objective of this work was to determine which treatment would be the best option in terms of degradation of NPnEO without the subsequent generation of toxic compounds. In order to investigate the degradation of the surfactant, the processes were compared in terms of UV/Vis spectrum, mineralization (total organic carbon), reaction kinetics, energy efficiency and phytotoxicity. A solution containing NPnEO was prepared as a surrogate of the degreasing wastewater, was used in the processes. The results showed that the photo-assisted processes degrade the surfactant, producing biodegradable intermediates in the reaction. On the other hand, the electrochemical process influences the mineralization of the surfactant. The process of PEO carried out with a 250W lamp and a current density of 10mA/cm(2) showed the best results in terms of degradation, mineralization, reaction kinetics and energy consumption, in addition to not presenting phytotoxicity. Based on this information, this process can be a viable alternative for treating wastewater containing NPnEO, avoiding the contamination of water resources. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Phase Separation Kinetics in Isopycnic Mixtures of H2O/CO2/Ethoxylated Alcohol Surfactants

    Science.gov (United States)

    Lesemann, Markus; Paulaitis, Michael E.; Kaler, Eric W.

    1999-01-01

    Ternary mixtures of H2O and CO2 with ethoxylated alcohol (C(sub i)E(sub j)) surfactants form three coexisting liquid phases at conditions where two of the phases have equal densities (isopycnic phases). Isopycnic phase behavior has been observed for mixtures containing C8E5, C10E6, and C12E6 surfactants, but not for those mixtures containing either C4E1 or C8E3 surfactants. Pressure-temperature (PT) projections for this three-phase equilibrium were determined for H2O/CO2/C8E5 and H2O/CO2/C10E6 mixtures at temperatures from approximately 25 to 33 C and pressures between 90 and 350 bar. Measurements of the microstructure in H2O/CO2/C12E6 mixtures as a function of temperature (25-31 C), pressure (63.1-90.7 bar), and CO2 composition (0-3.9 wt%) have also been carried out to show that while micellar structure remains essentially un-changed, critical concentration fluctuations increase as the phase boundary and plait point are approached. In this report, we present our first measurements of the kinetics of isopycnic phase separation for ternary mixtures of H2O/CO2/C8E5.

  10. Electrochemical regeneration of partially ethoxylated polyethylenimine used in the polymer-supported ultrafiltration of copper

    Energy Technology Data Exchange (ETDEWEB)

    Llanos, Javier, E-mail: javier.llanos@uclm.es [Chemical Engineering Department, University of Castilla-La Mancha, Edificio Enrique Costa Novella, Campus Universitario s/n, 13071 Ciudad Real (Spain); Perez, Angel; Rodrigo, Manuel A.; Canizares, Pablo [Chemical Engineering Department, University of Castilla-La Mancha, Edificio Enrique Costa Novella, Campus Universitario s/n, 13071 Ciudad Real (Spain)

    2009-08-30

    This work is focussed on the application of an electrochemical technology to regenerate the bonding agent of a polymer-supported ultrafiltration process, technique commonly used to remove metal ions from wastewaters. To do this, a batch rotating-electrode electrochemical cell has been set up to recover the copper bind to partially ethoxylated polyethyleneimine by electrodeposition. The influence of the main parameters (current efficiency, stirring rate, pH, electrode material and nature of the counterion) on the performance of the process has been studied. Current efficiency is clearly enhanced with the stirring rate, reaching values as high as 0.93 for the optimum working conditions. Regarding pH, this variable has been observed to play an important role in process efficiency. Thus, it has been found that the reactor can operate at pH 4 without affecting process performance. This is a clear advantage with respect to other regeneration techniques and also to previous works of electrochemical regeneration. The electrode material seems to have a clear influence on process behaviour and especially on the appearance of a first transitory stage with lower current efficiency. Finally, the electrolyte salt also influences significantly on the results and the presence of sulphate as counterion leads to the best system performance.

  11. Biotransformation of nonylphenol ethoxylates during sewage treatment under anaerobic and aerobic conditions

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Biotransformation of nonylphenol ethoxylates (NPEOs) during continuous anaerobic sewage treatment was compared with the aerobic treatment of sewage spiked with 23 μmol/L technical NPEOs over a period of 90 d. Immediate degradation of NPEOs was observed under both anaerobic and aerobic conditions, indicating that the enzymes and bacteria required for NPEO degradation existed abundantly in both aerobic and anaerobic sludge. Both treatments achieved high removal (>92%) of the spiked NPEO9 mixture.Liquid chromatography-mass spectrometry (LC-MS) analysis showed that short-chain NPEOs (NPEO1-NPEO3) accumulated in anaerobic (2.01-2.56 μmol/L) and aerobic (1.62-2.03 μmol/L) effluents, with nonylphenol (NP) (0.24-0.31 μmol/L) as another group of metabolites in the anaerobic effluent, and nonylphenoxy carboxylates (NPECs) (2.79-3.30 μmol/L) in the aerobic effluent. Significant accumulation of NP in the anaerobic sludge and NPEO1-3 in the sludge of two reactors was observed. These results indicated that it was difficult to control these harmful metabolites in the conventional treatment processes. Denaturing gradient gel electrophoresis profiles of sludge samples support the speculation that the NPEO degradation bacteria might be the dominant indigenous species.

  12. Vertical distribution of nonylphenol and nonylphenol ethoxylates in sedimentary core from the Beipaiming Channel, North China

    Institute of Scientific and Technical Information of China (English)

    JIN Fen; HU Jian-ying; YANG Min

    2007-01-01

    The vertical profiles of nonylphenol(NP)and nonylphenol ethoxylates(NPEOs) were investigated in a sediment core from the Beipaiming Channel,North China using high sensitive LC-MS and GC-MS methods.In this core,relatively high concentrations of NP and NPEOS occurred in the surface sediment(≤40 cm),with the maximum value of NP and NPEOs reaching 3539 and 12735 ng/g,respectively,whereas,no NP or NPEOs were detected in deeper sediments(>40 cm).The high concentrations of NP and NPEOs in the surface layers suggested recent inputs in this area.NPEOs with short ethoxy chains(NPnEO,n=0-3)were dominant in the NPEO mixture with percentages from 54%tO 78%.which were similar to the distribution of homolog NPEO in efttuents from nearby sewage treatment plants(STPs).indicating that the channel received the effluents from these STPs.The sewage treatment ratio was quite similar to that found in North America before the 1980s.Finally,the concentrations of NP and NPEOS were related to the total organic carbon(TOC)(P<0.001),suggesting that TOC was an important factor for vertical distribution of NPEOs and NP from the Beipaiming Channel.

  13. Decreases in surface activities and aquatic toxicities of linear alkylbenzene sulfonate and alcohol ethoxylates during biodegradation.

    Science.gov (United States)

    Oya, Masaru; Hisano, Noriko

    2010-01-01

    We discussed the relation between aquatic toxicity and interfacial activity during biodegradation with using LAS (Linear Alkylbenzene Sulphonate) and AE (Alcohol Ethoxylate). The change of death rate of Daphnia magna, surface tension, concentration of surfactant, and biodegradation by oxygen demand during biodegradation were measured. As a result, a rapid decrease in toxicity and rapid increase in surface tension were observed within the time before biodegradation based on oxygen demand started to increase. These rapid changes in toxicity and surface tension occurred due to the structural change of surfactant molecules in the primary biodegradation process, which was confirmed by HPLC (High Performance Liquid Chromatography) analysis. We also performed re-addition test to study the effects of acclimatization since it takes an important role on boidegradation, and found that the acclimatization significantly accelerated the primary biodegradation, which were indicated by increase in surface tension and decrease in aquatic toxicity. These results show that the environmental risk of surfactants should be considered not only with the biodegradation based on oxygen demand but also with the decrease of interfacial activity through the primary biodegradation process.

  14. Degradation of the commercial surfactant nonylphenol ethoxylate by advanced oxidation processes

    Energy Technology Data Exchange (ETDEWEB)

    Wohlmuth da Silva, Salatiel, E-mail: salatielws@gmail.com [Universidade Federal do Rio Grande do Sul (UFRGS) – Programa de Pós-Graduação em Engenharia de Minas, Metalúrgica e de Materiais (PPGEM), Av. Bento Gonçalves, 9500, Porto Alegre, RS (Brazil); Klauck, Cláudia Regina, E-mail: claudiark@feevale.br [Universidade Feevale, Campus II ERS-239, 2755, Novo Hamburgo, RS (Brazil); Siqueira, Marco Antônio, E-mail: marcor@feevale.br [Universidade Feevale, Campus II ERS-239, 2755, Novo Hamburgo, RS (Brazil); Bernardes, Andréa Moura, E-mail: amb@ufrgs.br [Universidade Federal do Rio Grande do Sul (UFRGS) – Programa de Pós-Graduação em Engenharia de Minas, Metalúrgica e de Materiais (PPGEM), Av. Bento Gonçalves, 9500, Porto Alegre, RS (Brazil)

    2015-01-23

    Highlights: • NP{sub 4}EO in industrial effluents can be treated before reaching water reservoirs. • Advanced oxidation processes are proposed for the degradation of NP{sub 4}EO. • The degradation rate depends mainly on the light intensity. • The mineralization rate depends mainly on the current density. • Photo-assisted electrochemical oxidation showed the best degradation results. - Abstract: Four different oxidation process, namely direct photolysis (DP) and three advanced oxidation processes (heterogeneous photocatalysis – HP, eletrochemical oxidation – EO and photo-assisted electrochemical oxidation – PEO) were applied in the treatment of wastewater containing nonylphenol ethoxylate (NP{sub n}EO). The objective of this work was to determine which treatment would be the best option in terms of degradation of NP{sub n}EO without the subsequent generation of toxic compounds. In order to investigate the degradation of the surfactant, the processes were compared in terms of UV/Vis spectrum, mineralization (total organic carbon), reaction kinetics, energy efficiency and phytotoxicity. A solution containing NP{sub n}EO was prepared as a surrogate of the degreasing wastewater, was used in the processes. The results showed that the photo-assisted processes degrade the surfactant, producing biodegradable intermediates in the reaction. On the other hand, the electrochemical process influences the mineralization of the surfactant. The process of PEO carried out with a 250 W lamp and a current density of 10 mA/cm{sup 2} showed the best results in terms of degradation, mineralization, reaction kinetics and energy consumption, in addition to not presenting phytotoxicity. Based on this information, this process can be a viable alternative for treating wastewater containing NP{sub n}EO, avoiding the contamination of water resources.

  15. Alkylphenols and alkylphenol ethoxylates contamination of crustaceans and fishes from the Adriatic Sea (Italy).

    Science.gov (United States)

    Ferrara, Fulvio; Fabietti, Fabio; Delise, Mirella; Funari, Enzo

    2005-05-01

    This paper presents the results of an investigation on the occurrence of alkylphenols (APs) and their ethoxylates (APEs) in 8 edible marine species from the Adriatic Sea and tries to estimate the corresponding intake for the Italian population. Two crustaceans, Nephrops norvegicus (Norway lobster) and Squilla mantis (spottail mantis shrimp), plus six fish species, Engraulis enchrascicolus (anchovy), Scomber scombrus (Atlantic mackerel), Merluccius merluccius (European hake), Mullus barbatus (red mullet), Solea vulgaris (common sole) and Lophius piscatorius (angler) were analyzed for their content of nonylphenol (NP), octylphenol (OP) and octylphenol polyethoxylates (OPEs). These compounds were found in all analysed samples. NP was detected at the highest concentrations: 118-399 and 9.5-1431 ng g(-1) fresh weight (fw) respectively in crustaceans and fish. OP was found at respective levels of 2.7-4.7 and 0.3-3.8 ng g(-1) fw in crustaceans and fish, whereas OPE was determined at respective concentrations of 1.2-16.8 and 0.2-21.1 ng g(-1) fw in the same species. These results, together with those from a previous study on 4 edible mollusc, allow to estimate respective daily intakes for NP, OP, and OPE of about 12, 0.1, and 0.1 microg day(-1) for an Italian adult living along the Adriatic Coast. In relation to NP and OP, these intakes are much lower than the doses associated with toxic effects in laboratory animals (9 mg kg(-1) bw for rats). Nevertheless, data of exposure from other sources to these chemicals and others with similar biological characteristics are needed.

  16. Partitioning of alcohol ethoxylates and polyethylene glycols in the marine environment: Field samplings vs laboratory experiments

    Energy Technology Data Exchange (ETDEWEB)

    Traverso-Soto, Juan M. [Departamento de Química Física, Facultad de Ciencias del Mar y Ambientales, Campus de Excelencia Internacional del Mar (CEI-MAR), Universidad de Cádiz, Campus Río San Pedro s/n, Puerto Real, Cádiz 11510 (Spain); Brownawell, Bruce J. [School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794-5000 (United States); González-Mazo, Eduardo [Departamento de Química Física, Facultad de Ciencias del Mar y Ambientales, Campus de Excelencia Internacional del Mar (CEI-MAR), Universidad de Cádiz, Campus Río San Pedro s/n, Puerto Real, Cádiz 11510 (Spain); Lara-Martín, Pablo A., E-mail: pablo.lara@uca.es [Departamento de Química Física, Facultad de Ciencias del Mar y Ambientales, Campus de Excelencia Internacional del Mar (CEI-MAR), Universidad de Cádiz, Campus Río San Pedro s/n, Puerto Real, Cádiz 11510 (Spain)

    2014-08-15

    Nowadays, alcohol ethoxylates (AEOs) constitute the most important group of non-ionic surfactants, used in a wide range of applications such as household cleaners and detergents. Significant amounts of these compounds and their degradation products (polyethylene glycols, PEGs, which are also used for many other applications) reach aquatic environments, and are eliminated from the water column by degradation and sorption processes. This work deals with the environmental distribution of AEOs and PEGs in the Long Island Sound Estuary, a setting impacted by sewage discharges from New York City (NYC). The distribution of target compounds in seawater was influenced by tides, consistent with salinity differences, and concentrations in suspended solid samples ranged from 1.5 to 20.5 μg/g. The more hydrophobic AEOs were mostly attached to the particulate matter whereas the more polar PEGs were predominant in the dissolved form. Later, the sorption of these chemicals was characterized in the laboratory. Experimental and environmental sorption coefficients for AEOs and PEGs showed average values from 3607 to 164,994 L/kg and from 74 to 32,862 L/kg, respectively. The sorption data were fitted to a Freundlich isotherm model with parameters n and log K{sub F} between 0.8–1.2 and 1.46–4.39 L/kg, respectively. AEO and PEG sorptions on marine sediment were also found to be mostly not affected by changes in salinity. - Highlights: • AEO and PEG levels in estuaries are influenced by tides and suspended solids. • Sediment–water partition coefficients in the lab and in the field are comparable. • Sorption is depending on both hydrophilic and hydrophobic interactions. • Sorption data fits Freundlich isotherms, showing K{sub F} values from 29 to 24,892 L/kg. • Sorption is very weakly influenced by salinity changes.

  17. Muon catalyzed fusion

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, K. [Advanced Meson Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Nagamine, K. [Muon Science Laboratory, IMSS-KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Matsuzaki, T. [Advanced Meson Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Kawamura, N. [Muon Science Laboratory, IMSS-KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

    2005-12-15

    The latest progress of muon catalyzed fusion study at the RIKEN-RAL muon facility (and partly at TRIUMF) is reported. The topics covered are magnetic field effect, muon transfer to {sup 3}He in solid D/T and ortho-para effect in dd{mu} formation.

  18. Determination of the fate of alcohol ethoxylate homologues in a laboratory continuous activated-sludge unit study.

    Science.gov (United States)

    Wind, T; Stephenson, R J; Eadsforth, C V; Sherren, A; Toy, R

    2006-05-01

    Environmental monitoring indicates that the distribution of alcohol ethoxylate (AE) homologues in wastewater treatment plant (WWTP) effluents differs from the distribution in commercial AE products, with a relative higher proportion of fatty alcohol (AOH, which is AE with zero ethoxylation). To determine the contribution of AE-derived AOH to the total concentration of AE and AOH in WWTP effluents, we conducted a laboratory continuous activated-sludge study (CAS). This consisted of a test unit fed with AE-amended synthetic sewage and a control unit fed with only synthetic sewage to avoid AE contamination from the feed. The removal efficiencies of some 114 AE homologues were determined by the application of a specific and sensitive analytical method. The extent of the removal of AE ranged from 99.70% for C18 compounds to > 99.98% for C12-16. Relatively high-AOH concentrations were observed in the effluents from blank and test units. By building the concentration difference from the test minus the control unit, the AE in the CAS effluent originating from AE in the influent was determined. Thus, it could be shown that AOH represented only 19% of the total AE (EO0-18) in the CAS, while monitoring in 29 WWTP effluents (European, Canadian, and US) revealed in total a mean AOH fraction of 55% (5-82%) of the total AE (EO0-18). This shows that only a small fraction of AOH in WWTP effluents originates from AE entering the WWTP.

  19. Synthesis and Properties of Laurylbenzyl Ethoxylates%十二烷基苄基聚氧乙烯醚的合成与性能

    Institute of Scientific and Technical Information of China (English)

    孙美玲; 梁雪芬; 胡学一; 岳成光

    2016-01-01

    Six kinds of laurylbenzyl ethoxylates(LBEOn) with different numbers, n, of ethylene oxide (EO) unit (n=4, 5, 7, 9, 11, or 13) were synthesized starting from laurylbenzyl alcohol by ethoxylation. The performance of surfactants were determined. Compared to the most commonly used alkylphenol ethoxylate, nonylphenol ethoxylate (trade name TX-10), LBEO9 has similar performance as TX-10. This LBEOn may be an effective alternative to TX-10.%研究了以十二烷基苄醇为原料进行乙氧基化反应,合成了6种具有不同乙氧基数(其乙氧基数分别为4,5,7,9,11和13)的十二烷基苄基聚氧乙烯醚(LBEOn)非离子表面活性剂,测定其性能并与最常用的烷基酚聚氧乙烯醚——壬基酚聚氧乙烯(9)醚(商品名TX-10)比较,发现乙氧基数为9的LBEOn的性能与TX-10接近,可能成为TX-10的有效替代品。

  20. Soft matter dispersions with ordered inner structures, stabilized by ethoxylated phytosterols.

    Science.gov (United States)

    Libster, Dima; Aserin, Abraham; Yariv, Doron; Shoham, Gil; Garti, Nissim

    2009-11-01

    This paper describes the formation and characterization of liquid crystalline dispersions based on the hexagonal phase of GMO/tricaprylin/water. As a stabilizer of the soft particles dispersed in the aqueous phase, a non-ionic, non-polymeric surfactant--ethoxylated phytosterol with 30 oxyethylene units (PhEO) was utilized. In contrast to Pluronic copolymers, normally utilized in the stabilization of liquid crystalline dispersions with ordered inner structure, use of such non-polymeric surfactant is not a common practice in this field. We revealed how properties of these particles, such as internal structure, size, and stability, can be rationally modified by the concentration of the stabilizing agent and processing conditions. The physical stability of the hexosomes was further examined by the LUMiFuge technique. Structural effect of PhEO solubilization on the properties of the bulk H(II) mesophase system showed that phase behavior was greatly influenced following phase transitions: H(II)-->H(II)+cubic-->cubic+L(alpha)-->L(alpha). The decrease of hydrogen bonding of the hydroxyl and carbonyl groups of monoolein with water and simultaneous hydration of EO groups of PhEO appeared to be important for the observed behavior. The use of PhEO as a dispersant resulted in a soft matter multi-phase water dispersion with bimodal distribution of the particle population. Effective stabilization of hexosomes was obtained in an extremely narrow concentration range of PhEO (0.1-0.2 wt%), coexisting with small vesicles and disordered particles. At higher PhEO content, particles had disordered inner structure, and unilamellar and multilamellar vesicles, at the expense of hexosomes in consequence of incorporation of the dispersant into the hexosome structure. PhEO was found to induce lamellar phase formation, introducing disorder into the hexagonal LLC and reducing their domain size. Finally, hexosomes were evaluated as delivery vehicles for the therapeutic peptide desmopressin

  1. 脂肪醇醚硫酸盐直接转化合成醇醚磺酸盐%Synthesis of ethoxylated fatty alcohol sulfonate by direct conversion of ethoxylated fatty alcohol sulfate

    Institute of Scientific and Technical Information of China (English)

    杨铭; 郭奕; 陈楠; 方云; 张丽萍

    2011-01-01

    Synthesis of ethoxylated fatty alcohol sulfonate (AESO) from direct conversion of ethoxylated fatty alcohol sulfate (AES- 3 ) was studied by using single factor experiment and orthogonal experiment method.The experiment results indicated that the yield of AESO was as high as 75.4% along with only 4.6% of hydrolysis rate of AES under the optimized reaction conditions: n ( SO32 - )∶ n ( AES - 3 ) = 4∶ 1, x ( Na2SO3 ) = 92% and w ( AES - 3 ) = 14% in aqueous solution at 190 ℃ for 4 h.Additionally, three other sulfate salts AES - 2, sodium dodecyl sulfate (SDS) and sodium nonylphenyl polyoxyethylene ether sulfate ( NPS - 4 ) were prepared under the same conditions, and 72.3% ,73.5% and 67.4% product yield was obtained respectively.%采用单因素法和正交分析法研究了脂肪醇聚氧乙烯醚(3)硫酸钠(AES-3)直接转化合成脂肪醇聚氧乙烯醚磺酸钠(AESO)工艺.结果表明,优化反应条件为:ω(AES-3)=14%,n(SO32-):n(AES-3)=4:1,x(Na2SO3)=92%,190℃压热条件下反应4 h,磺化率为75.4%,水解率为4.6%.在上述工艺条件下磺化脂肪醇聚氧乙烯醚(2)硫酸钠、十二烷基硫酸钠和壬基酚聚氧乙烯醚(4)硫酸钠的磺化率分别为72.3%,73.5%和67.4%.

  2. Catalyzed Ceramic Burner Material

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, Amy S., Dr.

    2012-06-29

    Catalyzed combustion offers the advantages of increased fuel efficiency, decreased emissions (both NOx and CO), and an expanded operating range. These performance improvements are related to the ability of the catalyst to stabilize a flame at or within the burner media and to combust fuel at much lower temperatures. This technology has a diverse set of applications in industrial and commercial heating, including boilers for the paper, food and chemical industries. However, wide spread adoption of catalyzed combustion has been limited by the high cost of precious metals needed for the catalyst materials. The primary objective of this project was the development of an innovative catalyzed burner media for commercial and small industrial boiler applications that drastically reduce the unit cost of the catalyzed media without sacrificing the benefits associated with catalyzed combustion. The scope of this program was to identify both the optimum substrate material as well as the best performing catalyst construction to meet or exceed industry standards for durability, cost, energy efficiency, and emissions. It was anticipated that commercial implementation of this technology would result in significant energy savings and reduced emissions. Based on demonstrated achievements, there is a potential to reduce NOx emissions by 40,000 TPY and natural gas consumption by 8.9 TBtu in industries that heavily utilize natural gas for process heating. These industries include food manufacturing, polymer processing, and pulp and paper manufacturing. Initial evaluation of commercial solutions and upcoming EPA regulations suggests that small to midsized boilers in industrial and commercial markets could possibly see the greatest benefit from this technology. While out of scope for the current program, an extension of this technology could also be applied to catalytic oxidation for volatile organic compounds (VOCs). Considerable progress has been made over the course of the grant

  3. Synthesis of Ethoxylated Carboxylates Under Reduced Pressure%减压法合成醇醚和酚醚羧酸盐

    Institute of Scientific and Technical Information of China (English)

    尹素红; 刘云

    2001-01-01

    Ethoxylated carboxylates are excellent surfactants. Their synthetic method from ethoxylated alcohols, chlorocetic acid and sodium hydroxide under reduced pressure is described. The optimum technical conditions for carboxymethylation were studied.%醇醚和酚醚羧酸盐是一种性能温和、无毒、生物降解性表面活性剂。报道了以醇醚(酚醚)、一氯乙酸和氢氧化钠为原料通过减压除水法合成醇醚(酚醚)羧酸盐的方法和限制一氯乙酸钠的情况下合成反应的最佳条件。

  4. Comprehensive analysis of fatty alcohol ethoxylates by ultra high pressure hydrophilic interaction chromatography coupled with ion mobility spectrometry mass spectrometry using a custom-designed sub-2 μm column.

    Science.gov (United States)

    Ma, Qiang; Ma, Wei; Chen, Xi; Wang, Ziming; Bai, Hua; Zhang, Lanwei; Li, Wentao; Wang, Chao; Li, Xinshi

    2015-06-01

    Comprehensive analysis of fatty alcohol ethoxylates has been conducted by coupling ultra high pressure hydrophilic interaction chromatography and ion mobility spectrometry mass spectrometry. A custom-designed sub-2 μm column was used for the chromatographic separation of fatty alcohol ethoxylates by hydrophilic interaction chromatography. Ion mobility spectrometry provided a post-ionization resolution during a very short period of 6.4 ms. Distinguishable families of singly, doubly, and triply charged fatty alcohol ethoxylates were clearly observed. By virtue of the combination of hydrophilic interaction chromatography and ion mobility spectrometry, comprehensive resolution based on both hydrophobicity difference and mobility disparity has been achieved for fatty alcohol ethoxylates. The orthogonality of the developed separation and analysis system was evaluated with the correlation coefficient and peak spreading angle of 0.0224 and 88.72°, respectively. The actual peak capacity obtained was individually 40 and 193 times than those when hydrophilic interaction chromatography and ion mobility spectrometry were used alone. The collision cross-sections of fatty alcohol ethoxylates were calculated by calibrating the traveling wave ion mobility device with polyalanine.

  5. Presence of nonylphenol ethoxylate surfactants in a watershed in central Mexico and removal from domestic sewage in a treatment wetland.

    Science.gov (United States)

    Belmont, Marco A; Ikonomou, Michael; Metcalfe, Chris D

    2006-01-01

    The Texcoco River in central Mexico is polluted with domestic wastewater as a result of discharges of untreated or inadequately treated sewage. Since nonylphenol ethoxylate (NPEO) surfactants and their intermediate degradation products such as nonylphenol (NP) and NP mono- and diethoxylate (NP1EO, NP2EO) have been found in domestic wastewater and in surface waters near wastewater discharges in industrialized countries, the Texcoco River was sampled to determine whether these compounds were present. The results indicated that NPEOs were present at very high concentrations (> 100 microg/L) in the lower reaches of the Texcoco River, but unlike rivers in industrialized countries, relatively low concentrations of intermediate degradation products, including NP1EO, NP2EO, and NP, were present. The presence and fate of NPEOs compounds in wastewater treatment plants have been studied only in conventional treatment systems in industrialized countries. In this study, the fate of these compounds was studied in a pilot-scale treatment wetland constructed in the small community of Santa Maria Nativitas in the Texcoco River watershed. The treatment wetland removed > 75% of NPEOs from the domestic wastewater, but the greatest proportion of removal occurred in parts of the treatment wetland where sedimentation existed. This is the first report of NPEO compounds in the water resources of a developing country. These data indicate that construction of low-cost and technologically simple treatment wetlands may be one solution to reducing the impacts of contaminants from domestic sewage in developing countries, such as Mexico.

  6. Fate of nonylphenol ethoxylate (NPEO) and its inhibitory impact on the biodegradation of acetate under aerobic conditions.

    Science.gov (United States)

    Ekdal, Alpaslan

    2014-01-01

    This study evaluated the kinetics of nonylphenol ethoxylate (NPEO) and acetate biodegradation at a moderate sludge age by acclimated culture under aerobic conditions. A laboratory-scale sequencing batch reactor was set and fed only with acetate mixture. The system was operated at steady state with a sludge age of 8 days. Following this stage, a mixture of NPEO and acetate was fed to the mixed culture in order to assess the biodegradation kinetics of NPEO and its impact on acetate utilization. A mechanistic model was developed involving model components and kinetic parameters for both substrates. The model was calibrated with parameters such as oxygen uptake rate and polyhydroxyalkanoates. Biodegradation characteristics and kinetics of acetate and NPEO were estimated by using the model results. Evaluation of calibrated model indicated that exposure of NPEO to non-acclimated sludge caused significant inhibitory impact on the utilization and storage of acetate. However, acclimation ofbiomass greatly suppressed inhibitory effects of NPEO on growth process involved in the degradation of acetate.

  7. Synthesis and Ethoxylation of Poly Methyl Acrylate%聚丙烯酸甲酯齐聚物的合成及乙氧基化

    Institute of Scientific and Technical Information of China (English)

    杜鹏飞; 孙永强; 康保安; 田春花; 刘广宇; 史修启; 张勇

    2011-01-01

    以四氩呋喃为溶剂,正十二硫醇为链转移剂,采用自由基溶液聚合的方法合成了聚丙烯酸甲酯齐聚物.考察了单体滴加时闻对黏均分子量的影响,确定滴加时间为40 min可以得到较低黏均分子量的聚丙烯酸甲酯齐聚物.在自制的插入式酯基乙氧基化催化荆MCT-09催化下成功地对聚丙烯酸甲酯齐聚物进行了乙氧基化反应.反应结果显示,随着反应进行,催化剂活性下降,乙氧基化反应速度逐渐降低.采用红外光谱对聚丙烯酸甲酯齐聚物及其乙氧基化物进行了结构表征.%Poly methyl acrylate(PMA) was synthesized by the method of free radical solvent polymerization using the tetrahydrofuran as solvent and the n-dodecyl mercaptan as chain transfer agent. The effect of the monomer dropping time on the viscosity molecular weight was tested. The results show that poly methyl acrylate with low viscosity molecular weight can be obtained when the monomer dropping time is set to be 40 minutes approximately.Following, with the help of self-made inserting ester ethoxylation catalyst MCT-09 the poly methyl acrylate is carriedout the ethoxylation successfully. The reaction results demonstrate that with the reaction carried through, the reaction rate decreases gradually due to the catalyst activity decline. Finally, the structure of the PMA and PMA ethoxylate was characterized by infrared spectrum(IR).

  8. Acute toxicity and relationship between metabolites and ecotoxicity during the biodegradation process of non-ionic surfactants: fatty-alcohol ethoxylates, nonylphenol polyethoxylate and alkylpolyglucosides.

    Science.gov (United States)

    Jurado, E; Fernández-Serrano, M; Núñez-Olea, J; Luzón, G; Lechuga, M

    2009-01-01

    The toxicity values of fatty-alcohol ethoxylates, nonylphenol polyethoxylate, and alkylpolyglucosides have been determined by applying assays with luminescent bacteria. Also, the relation between metabolites and ecotoxicity during the biodegradation process has been determined. The biodegradation tests were carried out according to the OECD 301 E test for ready biodegradability. In these tests a solution of the surfactant, representing the sole carbon source for the microorganisms, was tested in a mineral medium, inoculated and incubated under aerobic conditions in the dark. The toxicity of surfactants is related to their molecular structure (Quantitative Structure Activity Relationships, QSAR). For the alkylpolyglucosides, toxicity expressed as EC(50) is related with the critical micelle concentration (CMC), the hydrophilic-lipophilic balance (HLB) of the surfactant, and the hydrophobic alkyl chain (R). The results indicate that toxicity increased as the CMC decreased and as the hydrophobicity increased and R rose. For fatty-alcohol ethoxylates, parameters characteristic studied have been HLB, number of units of ethylene oxide and the alkyl chain length. Relationships found are in agreement with the fact that increasing the alkyl chain length leads to a lower EC(50), whereas increasing ethoxylation leads to a lower toxicity. An analysis of the behaviour of the toxicity and HLB again indicates that the toxicity was greater for surfactants with a smaller HLB. The evolution of the toxicity was studied over the biodegradation process, expressed as a percentage of inhibition. For all the non-ionic surfactants assayed, except for the nonylphenol polyethoxylate, a major decline was found in toxicity during the first days of the biodegradation assay and at all the concentrations tested.

  9. 十二烷基苄醇聚氧乙烯醚的合成及性能%Synthesis and physicochemical properties of ethoxylated lauryl benzyl alcohol

    Institute of Scientific and Technical Information of China (English)

    陆颖; 刘雪锋; 方云

    2012-01-01

    Ethoxylated lauryl benzyl alcohol (LBAEOn) ,was synthesized starting from n - dodecylbenzene by a three - step process including chloromethylation, hydrolysis and ethoxylation. Structure of the LBAEOn was characterized by FTIR and 1HNMR, and number of EO moles adducted n =9.5. Distribution of EO mole number in the LBAEO, was characterized by ESI - MS. Critical micelle concentration ( cmc) and surface tension at cmc (γcmc) of the product is 1. 83 × 10-6 mol · L-1 and 39. 0 mN ? m-1 respectively, which were measured by surface tension method at 25 ℃. In comparison with common nonionic surfactants such as ethoxylated fatty alcohol ( AEO9) and ethoxylated nonyl phenol ( NPEO10) , surface activity of the LBAEOn is higher while the foaming power is lower and lime soap dispersing power is similar. Solubilization capacity to octanol of the LBAEOn is higher,and wetting power is lower.%以十二烷基苯为原料,经氯甲基化、水解及环氧乙基化等步骤得到平均乙氧基(EO)数为9.5的十二烷基苄醇聚氧乙烯醚(LBAEOn).分别用FTlR和1HNMR表征了产物LBAEOn的结构特征,并用ESI - MS确定了LBAEOn中的EO分布.以表面张力法测得在25℃时LBAEOn的cmc和γcmc分别为1.83×10-6mol·L-1和39.0 mN·m-1;与脂肪醇聚氧乙烯醚(AEO9)和壬基酚聚氧乙烯醚(NPEO10)相比较,除钙皂分散性能大致相当以外,LBAEOn的表面活性较好、发泡力较低、对正辛醇的增溶能力较强和对帆布的润湿性能较差.

  10. Polyethylenimine Interfacial Layers in Inverted Organic Photovoltaic Devices: Effects of Ethoxylation and Molecular Weight on Efficiency and Temporal Stability.

    Science.gov (United States)

    Courtright, Brett A E; Jenekhe, Samson A

    2015-12-02

    We report a comparative study of polyethylenimine (PEI) and ethoxylated-polyethylenimine (PEIE) cathode buffer layers in high performance inverted organic photovoltaic devices. The work function of the indium-tin oxide (ITO)/zinc oxide (ZnO) cathode was reduced substantially (Δφ = 0.73-1.09 eV) as the molecular weight of PEI was varied from 800 g mol(-1) to 750 000 g mol(-1) compared with the observed much smaller reduction when using a PEIE thin film (Δφ = 0.56 eV). The reference inverted polymer solar cells based on the small band gap polymer PBDTT-FTTE (ITO/ZnO/PBDTT-FTTE:PC70BM/MoO3/Ag), without a cathode buffer layer, had an average power conversion efficiency (PCE) of 6.06 ± 0.22%. Incorporation of a PEIE cathode buffer layer in the same PBDTT-FTTE:PC70BM blend devices gave an enhanced performance with a PCE of 7.37 ± 0.53%. In contrast, an even greater photovoltaic efficiency with a PCE of 8.22 ± 0.10% was obtained in similar PBDTT-FTTE:PC70BM blend solar cells containing a PEI cathode buffer layer. The temporal stability of the inverted polymer solar cells was found to increase with increasing molecular weight of the cathode buffer layer. The results show that PEI is superior to PEIE as a cathode buffer layer in high performance organic photovoltaic devices and that the highest molecular weight PEI interlayer provides the highest temporal stability.

  11. Application of the GREAT-ER model for environmental risk assessment of nonylphenol and nonylphenol ethoxylates in China.

    Science.gov (United States)

    Zhang, Lai; Cao, Yan; Hao, Xuewen; Zhang, Yongyong; Liu, Jianguo

    2015-12-01

    The environmental risk presented by "down-the-drain" chemicals to receiving rivers in large urban areas has received increasing attention in recent years. Geo-referenced Regional Environmental Assessment Tool for European Rivers (GREAT-ER) is a typical river catchment model that has been specifically developed for the risk assessment of these chemicals and applied in many European rivers. By utilizing the new version of the model, GREAT-ER 3.0, which is the first completely open source software for worldwide application, this study represents the first attempt to conduct an application of GREAT-ER in the Wenyu River of China. Aquatic exposure simulation and an environmental risk assessment of nonylphenol (NP) and its environmental precursor nonylphenol ethoxylates (NPEOs) were conducted effectively by GREAT-ER model, since NP is one of typical endocrine disrupting chemicals (EDCs) and its environmental precursor NPEOs as a "down-the-drain" chemical are extensively used in China. In the result, the predicted environmental concentrations (PECs) of NP and NPEOs in the water of Wenyu River were 538 and 4320 ng/L, respectively, at the regional scale, and 1210 and 8990 ng/L, respectively, at the local scale. From the results profile of the RCR, the combination of high emissions from large STPs with insufficient dilution of the river caused the high RCR. The PECs of NP in the sediment were in the range of 216.8-8218.3 ng/g (dry weight), which was consistent with the available monitoring data. The study showed the worldwide applicability and reliability of GREAT-ER as a river catchment model for the risk assessment of these chemicals and also revealed the general environmental risks presented by NP and NPEOs in the Wenyu River catchment in Beijing due to the extensive use of these chemicals. The results suggest that specific control or treatment measures are probably warranted for these chemicals to reduce their discharge in major cities.

  12. A combined binding mechanism of nonionic ethoxylated surfactants to bovine serum albumin revealed by fluorescence and circular dichroism.

    Science.gov (United States)

    Iovescu, Alina; Băran, Adriana; Stîngă, Gabriela; Cantemir-Leontieş, Anca Ruxandra; Maxim, Monica Elisabeta; Anghel, Dan Florin

    2015-12-01

    The study systematically investigates aqueous mixtures of fixed bovine serum albumin (BSA) and various ethoxylated nonionic surfactants belonging to a homologous series or not. Mono-disperse tetra-(C12E4), hexa-(C12E6) and octa-ethyleneglycol mono-n-dodecyl ether (C12E8), and poly-disperse eicosa-ethyleneglycol mono-n-tetradecyl ether (C14EO20) are respectively employed. Fluorescence and circular dichroism measurements are performed at surfactant/protein molar ratios (rm)s lower and higher than one. We aim to get new insights into the binding mechanism of these species and to differentiate among the interaction abilities of these surfactants. The relative magnitude of the binding thermodynamic parameters by fluorescence, and the increase of α-helix prove that hydrogen bonding drives the interaction next to the hydrophobic attraction. C12En (n=4,6,8) develop more H bonds with the albumin than C14EO20 owing to a zigzag conformation of their short ethyleneoxide chains. Among the homologous surfactants, C12E6 has a slightly stronger interaction with BSA due to a maximal number of H bonds at a minimal hindering. Static fluorescence and dynamic fluorescence indicate an inter-conversion between the tryptophan (Trp) rotamers which happens around the surfactants critical micellar concentration. For C14EO20, the meander conformation of the polar group determines a less evident conversion of the Trp rotamers and smaller α-helix rise. Binding isotherms of the homologous surfactants and the fluorescence quenching mechanism by C12E6 are also provided.

  13. Production of mono- and di-carboxylated polyethylene glycols as a factor obstacle to the successful ozonation-assisted biodegradation of ethoxylated compounds.

    Science.gov (United States)

    Nakai, Satoshi; Okuda, Tetsuji; Nishijima, Wataru; Okada, Mitsumasa

    2015-10-01

    Ozonation is believed to improve the biodegradability of organic compounds. In the present study, degradation of nonylphenol ethoxylates (NPEOs) was monitored in hybrid treatment systems consisting of ozonation and microbial degradation processes. We found that ozonation of NPEOs decreased, rather than increased, the biodegradability under certain conditions. The timing of ozonation was a definitive factor in determining whether ozonation increased or decreased the biodegradation rates of NPEOs. Initial ozonation of NPEOs prior to biodegradation reduced the rate of dissolved organic carbon (DOC) removal during the subsequent 14 d of biodegradation, whereas intermediate ozonation at the 9th day of biodegradation improved subsequent DOC removal during 14 d of NPEO biodegradation. Furthermore, reduction of DOC removal was also observed, when initial ozonation prior to biodegradation was subjected to cetyl alcohol ethoxylates. The production of less biodegradable intermediates, such as mono- and dicarboxylated polyethylene glycols (MCPEGs and DCPEGs), was responsible for the negative effect of ozonation on biodegradability of NPEOs. DCPEGs and MCPEGs were produced by biodegradation of polyethylene glycols (PEGs) that were ozonolysis products of the NPEOs, and the biodegradability of DCPEGs and MCPEGs was less than that of the precursor PEGs. The results indicate that, if the target chemicals contain ethoxy chains, production of PEGs may be one of the important factors when ozonation is considered. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. 蓖麻油酸甲酯乙氧基化物洗涤性能的研究%Washing performance of ethoxylated castor oil acid methyl esters

    Institute of Scientific and Technical Information of China (English)

    张谦; 孙永强; 王万绪; 智丽飞; 张勇; 孙晋源; 武华萍

    2015-01-01

    The washing properties of different average ethylene oxide (EO) adduct number of ethoxylated castor oil acid methyl esters (ECAME) was tested and the hydrolysis resistant ability of ECAME was investigat-ed under different pH. The results showed that ethoxylated castor oil acid methyl esters with 14 of EO adduct number (ECAME- 14) had the best washing property. The hydrolysis rate of ECAME- 14 was low under pH=4~9 for 4 weeks. Under alkaline condition, the surface activity of ECAME- 14 was weakened while its surface ac-tivity was enhanced under acidic condition.%对不同平均环氧乙烷(EO)加合数的蓖麻油酸甲酯乙氧基化物(ECAME)的洗涤性能进行了测定,并考察了其在不同pH条件下的抗水解能力.结果表明,平均EO加合数为14的蓖麻油酸甲酯乙氧基化物(ECAME-14)的洗涤能力最好.在pH为4~9的溶液中放置4周,ECAME-14水解率很低.在碱性条件下,其表面活性被削弱,但在酸性条件下,其表面活性增强.

  15. 4-羟基-5-乙氧基苯胺的合成%Synthesis of 5-Ethoxyl-4-hydroxylaniline

    Institute of Scientific and Technical Information of China (English)

    李志华; 狄庆锋

    2013-01-01

    以苯胺为原料,经重氮化、偶合、还原得到4-羟基-5-乙氧基苯胺.合成中,通过保险粉还原偶氮化合物的方法在芳香环上引进氨基,不仅产物收率高(总收率86%,较文献提高了26.3%),而且还原产物容易分离,粗品纯度可达95%.本合成路线中间体均不经提纯,且氨基的引入中避免了贵金属的加氢还原,是一条适合大规模生产4-羟基-5-乙氧基苯胺的新合成工艺路线.%5-Ethoxyl-4-hydroxylaniline was prepared through diazotization of aniline,coupling with o-ethoxyl phenol and followed by the reduction of azo compounds with sodium hyposulfite in overall yield of 86% and 95% HPLC purity.The yield was increased by 26.3% compared with the literature.This synthesis avoids noble metal catalized hydrogenation and is suitable for mass production without purification of the intermediates.

  16. Modifying the adsorption properties of anionic surfactants onto hydrophilic silica using the pH dependence of the polyelectrolytes PEI, ethoxylated PEI, and polyamines.

    Science.gov (United States)

    Zhang, Xiaoli; Taylor, Diana; Thomas, Robert; Penfold, Jeffrey; Tucker, Ian

    2011-04-05

    The manipulation of the adsorption of the anionic surfactant, sodium dodecyl sulfate, SDS, onto hydrophilic silica by the polyelectrolytes, polyethyleneimine, PEI, ethoxylated PEI, and the polyamine, pentaethylenehexamine, has been studied using neutron reflectometry. The adsorption of a thin PEI layer onto hydrophilic silica promotes a strong reversible adsorption of the SDS through surface charge reversal induced by the PEI at pH 7. At pH 2.4, a much thicker adsorbed PEI layer is partially swelled by the SDS, and the SDS adsorption is now no longer completely reversible. At pH 10, there is some penetration of SDS and solvent into a thin PEI layer, and the SDS adsorption is again not fully reversible. Ethoxylation of the PEI (PEI-EO(1) and PEI-EO(7)) results in a much weaker and fragile PEI and SDS adsorption at both pH 3 and pH 10, and both polymer and surfactant desorb at higher surfactant concentrations (>critical micellar concentration, cmc). For the polyamine, pentaethylenehexamine, adsorption of a layer of intermediate thickness is observed at pH 10, but at pH 3, no polyamine adsorption is evident; and at both pH 3 and pH 10, no SDS adsorption is observed. The results presented here show that, for the amine-based polyelectrolytes, polymer architecture, molecular weight, and pH can be used to manipulate the surface affinity for anionic surfactant (SDS) adsorption onto polyelectrolyte-coated hydrophilic silica surfaces.

  17. Mass Transfer and Kinetics Study of Heterogeneous Semi-Batch Precipitation of Magnesium Carbonate

    DEFF Research Database (Denmark)

    Han, B.; Qu, H. Y.; Niemi, H.

    2014-01-01

    Precipitation kinetics and mass transfer of magnesium carbonate (MgCO3) hydrates from a reaction of magnesium hydroxide (Mg(OH)(2)) and CO2 were analyzed. The effect of CO2 flow rate and mixing intensity on precipitation was investigated under ambient temperature and atmospheric pressure. Raman...... on the dissolution of Mg(OH)(2). In the researched system, the main driver of the precipitation kinetics was the mass transfer of CO2. Nesquehonite (MgCO3 center dot 3H(2)O), as needle-like crystals, was precipitated as the main product. Raman spectroscopy can serve as a potential tool to monitor the carbonation...

  18. New extractive configuration separating azeotropic mixture in semi-batch way

    OpenAIRE

    Stéger, Csaba; Rev, Endre; Horvath, Laszlo; Fonyo, Zsolt; Meyer, Michel; Lelkes, Zoltan

    2006-01-01

    A new variant of batch extractive distillation, the so-called inverse-fed batch extractive distillation is presented. The total amount of the entrainer is pre-loaded to the boiler, and the mixture charge to be separated is continuously fed to the column in this novel configuration. The feasibility study of conventional extractive distillation was extended and a thorough study was performed to separate a maximum boiling azeotrope with intermediate boiling entrainer. The new configuration was f...

  19. Semi-batch absorption and regeneration studies for CO{sub 2} capture by aqueous ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, James T.; Resnik, Kevin P.; Rygle, Kathy; Pennline, Henry W. [U.S. Department of Energy, National Energy Technology Laboratory, P.O.Box 10940, Pittsburgh, PA 15236 (United States)

    2005-10-15

    Carbon dioxide transfer capacities of aqueous ammonia solution and monoethanolamine (MEA) solution were compared. The ammonia process for CO{sub 2} capture was simulated using a semibatch reactor, where the flow of gas is continuous. The CO{sub 2} carrying capacity in g CO{sub 2} per g of NH{sub 3} solution (8 wt.%) circulated is 0.07 as compared with 0.036 g CO{sub 2} per g MEA solution (20 wt.%). The energy requirement for liquid mass circulation of ammonia solution is approximately 50% of MEA solution for equal weight of CO{sub 2} carried. In another comparison, the thermal energy required to regenerate CO{sub 2} from the rich solution is substantially less as compared to the MEA process. A 3-cycle absorption-regeneration test was conducted in the semibatch reactor to simulate an approach-to-steady state in a flow system. pH values of the absorbent solution was found to oscillate between 9.6 (CO{sub 2}-lean) and 8.8 (CO{sub 2}-rich) under the test conditions. Thermodynamics study shows that ammonium bicarbonate required the least thermal energy among the ammonium compounds for CO{sub 2} regeneration. (author)

  20. Decolorization and semi-batch continuous treatment of molasses distillery wastewater by Aspergillus tubingensis DCT6.

    Science.gov (United States)

    Watanabe, T; Tanaka, M; Masaki, K; Fujii, T; Iefuji, H

    2009-01-01

    Large quantities of deeply pigmented molasses distillery wastewater (MDW), are discharged during the production of bio-ethanol from molasses. Conventional biological wastewater treatment is not effective in removing the molasses pigments. In the present study, a MDW treatment system was developed with combination treatment involving biodecolorization and biotreatment by Aspergillus tubingensis DCT6, together with physical decolorization by ozonation after treatment by activated sludge. A. tubingensis DCT6, which was isolated from soil, decolorized 44% of the pigments in MDW without adding any nutrients. The combination treatment with A. tubingensis DCT6 and activated sludge method (fungi-activated sludge treatment) removed about 90% of organic compounds from MDW and appears to reduce the amount of space and water required for treatment. The fungi-activated sludge treatment reduced the time needed for decolorization by ozone by 83%. Replacing fresh seed sludge at regular intervals was useful to maintain the dominance and decolorization ability of A. tubingensis DCT6. The entire treatment obtained a decolorization ratio of 89-94% and removed more than 90% of each of DOC, DTN, and DTP.

  1. Gold-Catalyzed Synthesis of Heterocycles

    Science.gov (United States)

    Arcadi, Antonio

    2014-04-01

    The following sections are included: * Introduction * Synthesis of Heterocycles via Gold-Catalyzed Heteroatom Addition to Unsaturated C-C Bonds * Synthesis of Heterocyclic Derivatives through Gold-Catalyzed Cyclization of Polyunsaturated Compounds * Synthesis of Heterocyclic Compounds via α-Oxo Gold Carbenoid * Synthesis of Heterocyclic Derivatives through Gold-Catalyzed Cycloaddition Reactions * Synthesis of Heterocyclic Derivatives through Gold-Catalyzed Activation of Carbonyl Groups and Alcohols * Synthesis of Heterocyclic Compounds through Gold-Mediated C-H Bond Functionalization * Gold-Catalyzed Domino Cyclization/Oxidative Coupling Reactions * Conclusions * References

  2. Gamma radiation/H{sub 2}O{sub 2} treatment of a nonylphenol ethoxylates: Degradation, cytotoxicity, and mutagenicity evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Munawar, E-mail: bosalvee@yahoo.com [National Center of Excellence in Physical Chemistry, University of Peshawar, Peshawar-25120 (Pakistan); Bhatti, Ijaz Ahmad [Department of Chemistry, University of Agriculture, Faisalabad-38040 (Pakistan)

    2015-12-15

    Highlights: • Nonylphenol ethoxylates undergone gamma ray/H{sub 2}O{sub 2} treatment. • Treatment efficiency was evaluated on the basis of degradation and toxicity reduction. • A significant reductions in COD and TOC were achieved. • Radiolytic by-products were low carbon carboxylic acids. • AOP reduced the cytotoxicity and mutagenicity considerably. - Abstract: Gamma radiation/H{sub 2}O{sub 2} treatment of nonylphenol polyethoxylates (NPEO) was performed and treatment effect was evaluated on the basis of degradation, chemical oxygen demand (COD) and total organic carbon (TOC), and toxicity reduction efficiencies. The radiolytic by-products were determined by Fourier Transform Infrared Spectroscopy (FTIR), High-Performance Liquid Chromatography (HPLC), and Gas Chromatography–Mass Spectrometry (GC–MS) techniques. Low mass carboxylic acids, aldehyde, ketone, and acetic acid were identified as the by-products of the NPEO degradation. NPEO sample irradiated to the absorbed dose of 15 kGy/4.58% H{sub 2}O{sub 2} showed more than 90% degradation. Allium cepa (A. cepa), brine shrimp, heamolytic tests were used for cytotoxicity study, while mutagenicity was evaluated through Ames test (TA98 and TA100 strains) of treated and un-treated NPEO. The reductions in COD and TOC were greater than 70% and 50%, respectively. Gamma radiation/H{sub 2}O{sub 2} treatment revealed a considerable reduction in cytotoxicity and mutagenicity. A. cepa, heamolytic and shrimp assays showed cytotoxicity reduction up to 68.65%, 77%, and 94%, respectively. The mutagenicity reduced up to 62%, 74%, and 79% (TA98) and 68%, 78%, and 82% (TA100), respectively of NPEO-6, NPEO-9, and NPEO-30 irradiated to the absorbed dose of 15 kGy/4.58% H{sub 2}O{sub 2}. NPEO-6 detoxified more efficiently versus NPEO-9 and NPEO-30 and results showed that Gamma radiation/H{sub 2}O{sub 2} treatment has the potential to mineralize and detoxify NPEO.

  3. Effect of O-4-ethoxyl-butyl-berbamine in combination with pegylated liposomal doxorubicin on advanced hepatoma in mice

    Institute of Scientific and Technical Information of China (English)

    Bai-Jun Fang; Mei-Li Yu; Shao-Guang Yang; Lian-Ming Liao; Jie-Wen Liu; Robert-C-H Zhao

    2004-01-01

    AIM:To study the synergistic effects of calmodulin (CaM) antagonist O-4-ethoxyl-butyl-berbamine (EBB) and pegylated liposomal doxorubicin (PLD) on hepatoma-22 (H22)in vivo.METHODS: Hepatoma model was established in 50 Balb/c mice by inoculating H22 cells (2.5x106) subcutaneously into the right backs of the mice. These mice were divided into 5 groups, and treated with saline only, PLD only, doxorubicin (Dox) only, PLD plus EBB and Dox plus EBB, respectively.In the treatment groups, mice were given 5 intravenous of PLD or Dox on days 0, 3, 6, 9 and 12. The first dosage of PLD or Dox was 4.5 mg/kg, the other 4 injections was 1 mg/kg.EBB (5 mg/kg)was coadministered with PLD or Dox in the corresponding groups. The effect of drugs on the life spans of hepatoma-bearing mice and tumor response to the drugs were recorded. Dox levels in the hepatoma cells were measured by a fluorescence assay. Light microscopy was performed to determine the histopathological changes in the major organs of these tumor-bearing mice. The MTT method was used to analyze the effect of Dox or PLD alone,Dox in combination with EBB, or PLD in combination with EBB on the growth of H22 cells in an in vitro experiment.RESULTS: EBB (5 mg/kg) significantly augmented the antitumor activity of Dox or PLD, remarkably prolonged the median survival time. The median survival time was 18.2 d for control group, but 89.2 d for PLD+EBB group and 70.1 d for Dox+EBB group, respectively. However,Dox alone did not show any remarkable antitumor activity,and the median survival time was just 29.7 d. Addition of EBB to Dox or PLD significantly increased the level of Dox in H22 cells in vivo. Moreover, EBB diminished liver toxicity of Dox and PLD.In vitro, EBB reduced the IC50 value of Dox or PLD on H22cells from 0.050±0.006 mg/L and 0.054±0.004 mg/L to 0.012±0.002 mg/L and 0.013±0.002 mg/L, respectively (P<0.01).CONCLUSION: EBB and liposomization could improve the therapeutic efficacy of Dox in liver cancer, while

  4. Lewis Acid Catalyzed Benzylic Bromination

    OpenAIRE

    Shibatomi, Kazutaka; Zhang, Yanhua; Yamamoto, Hisashi

    2008-01-01

    Lewis acid catalyzed bromination on aromatic side chain was achieved efficiently by using 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) as a bromination reagent under mild conditions. Zirconium(IV) chloride showed the highest catalytic activity for the benzylic bromination. It was revealed that the present Lewis acid catalysis proceeds via the radical generation pathway. In contrast to Lewis acid catalysis, Brønsted acid promoted aromatic ring bromination without any benzylic bromination. Monobro...

  5. Gold-catalyzed domino reactions.

    Science.gov (United States)

    Michelet, Véronique

    2015-01-01

    Gold-catalyzed reactions have appeared to be highly attractive tools for chemists to promote novel transformations to prepare elaborated structures from simple starting materials. This chapter presents selected and original examples of domino processes in the presence of gold catalysts, highlighting reports implying hydration, hydroxylation, and hydroamination as key starting point for cascade transformations. Domino processes implying 1,n-enynes, asymmetric domino transformations, and applications of all the presented processes in total synthesis are presented.

  6. Study on adsorption behavior of octylphenol ethoxylates on silk fabric%辛基酚聚氧乙烯醚在丝织物上的吸附行为研究

    Institute of Scientific and Technical Information of China (English)

    李文武; 宁小玉; 林型跑; 戴宏翔; 陈海相

    2016-01-01

    In this paper, the adsorption behavior of octylphenol ethoxylates on silk fabric including isotherm, kinetics and thermodynamics was studied. The influences of temperature and second component alkylphenol ethoxylates on adsorption were investigated. Moreover, the adsorption properties of octylphenol ethoxylates on five kinds of fabrics were compared. The results show that the adsorption isotherm of octylphenol ethoxylates on silk fabric could be well described by Langmuir-Freundlich equation, and the adsorption kinetics could be well described by quasi-second-order kinetic equation. The adsorption properties of octylphenol ethoxylates on five kinds of fabrics are sorted in descending order as follows:silk, cotton, linen, PET, PAN.%研究辛基酚聚氧乙烯醚在丝织物上的吸附行为,包括吸附等温线、动力学和热力学,以及温度和第二组分烷基酚聚氧乙烯醚对吸附的影响,同时比较了辛基酚聚氧乙烯醚在五种织物上的吸附性能。结果表明,辛基酚聚氧乙烯醚在丝织物上的吸附等温线可用Langmuir-Freundlich方程、吸附动力学可用准二阶动力学方程分别描述。辛基酚聚氧乙烯醚在五种织物上的吸附能力由强到弱依次为:丝,棉,麻,涤纶,腈纶。

  7. Thermodynamics of Enzyme-Catalyzed Reactions Database

    Science.gov (United States)

    SRD 74 Thermodynamics of Enzyme-Catalyzed Reactions Database (Web, free access)   The Thermodynamics of Enzyme-Catalyzed Reactions Database contains thermodynamic data on enzyme-catalyzed reactions that have been recently published in the Journal of Physical and Chemical Reference Data (JPCRD). For each reaction the following information is provided: the reference for the data, the reaction studied, the name of the enzyme used and its Enzyme Commission number, the method of measurement, the data and an evaluation thereof.

  8. The effects of detergent, sodium tripoly-phosphate and ethoxyled oleyl-cetyl alcohol on metabolic parameters of the fungus Trichothecium roseum link

    Directory of Open Access Journals (Sweden)

    Stojanović Jelica

    2011-01-01

    Full Text Available The degradation of detergents that are dispersed in water and soil partially depends on the metabolic activities of fungi. Among the fungi that have this ability, Deuteromycetes are particularly noted for their biochemical characteristics. Taking this into account, it was of interest to analyze the influence of detergent and its main compounds, ethoxyled oleylcetyl alcohol (AOC and sodium tripoly-phosphate (TTP, on the metabolism of the fungus Trichothecium roseum. Our results revealed that both detergent and AOC had an inhibitory effect on the bioproduction of free organic acids, while TTP stimulated their production. Also, detergent inhibited the bioproduction of basic amino acids, with the exception of alanine. In addition, detergent applied at 1% concentration inhibited the bioproduction of proteins and the total biomass of the fungus, while AOC and TTP inhibited the production of proteins, but stimulatedl the production of Trichothecium.

  9. Enlarging Capacity Design of PressⅡ Ethoxylation Device%普利斯二代乙氧基化装置扩能改造设计

    Institute of Scientific and Technical Information of China (English)

    刘伟

    2016-01-01

    提出了普利斯二代乙氧基化装置扩能改造设计方案,装置生产能力由5.2万t/a提高到7.5万t/a,综合能耗由51.3 kg Eo/t降至43.6 kg Eo/t,节约费用85.51元/t。%Enlarging capacity design project of PressⅡ ethoxylation device was mentioned, device production capacity was increased from 52 kt/a to 75 kt/a, synthesized power consumption was decreased from 51.3 kg Eo/t to 43.6 kg Eo/t.

  10. 醇醚糖苷柠檬酸单酯盐的制备与性能研究%Preparation and performance of citrate monoesters salt of ethoxylated fatty alcohols glucoside

    Institute of Scientific and Technical Information of China (English)

    牛少勇; 杨秀全; 白亮; 周媛; 张军

    2012-01-01

    Through indirect eaterification,citric acid anhydride was synthesized with citric acid and acetic anhydride as raw materials,the citrate monoesters were prepared with synthetic citric acid anhydride and ethoxylated fatty alcohols glucoside (containing excess ethoxylated fatty alcohols) ,and then neutralization with NaOH,Ca (OH)2 and Mg (OH)2 obtained the citrate monoesters disodium salt of ethoxylated fatty alcohols glucoside (MAEG-EC-Na) , citrate monoesters calcium salt of ethoxylated fatty alcohols glucoside (MAEC-EC-Ca) and citrate monoesters magnesium salt of ethoxylated fatty alcohols glucoside (MAEG- EC-Mg). The physicochemical properties of the products were measured. Results showed that the γcmc range of the three products are very small, and the one of citric acid monoester disodium salt of ethoxylated fatty alcohols glucoside is minimum. The order of foaming ability and foam stability of citric acid monoester salt is MAEG-EC-Mg > MAEG-EC-Ca > MAEG-EC-Na.%采用间接酯化法,以柠檬酸和乙酸酐为原料,先合成柠檬酸酐,后与醇醚糖苷(含有未反应的脂肪醇醚)反应,合成了醇醚糖苷柠檬酸单酯,再用NaOH溶液、饱和Ca(OH)2水溶液和Mg(OH)2乳浊液中和制得醇醚糖苷柠檬酸单酯二钠盐(MAEG-EC-Na)、醇醚糖苷柠檬酸单酯钙盐(MAEG-EC-Ca)和醇醚糖苷柠檬酸单酯镁盐(MAEGEC-Mg),对产物的物化性能进行了测定.结果表明,上述3种产品的γcmc变化范围均很小,而柠檬酸单酯二钠盐的cmc最小,柠檬酸单酯盐起泡性能、泡沫稳定性的顺序为MAEG-EC-Mg> MAEG-EC-Ca> MAEG-EC-Na.

  11. Iridium-Catalyzed Allylic Substitution

    Science.gov (United States)

    Hartwig, John F.; Pouy, Mark J.

    Iridium-catalyzed asymmetric allylic substitution has become a valuable method to prepare products from the addition of nucleophiles at the more substituted carbon of an allyl unit. The most active and selective catalysts contain a phosphoramidite ligand possessing at least one arylethyl substituent on the nitrogen atom of the ligand. In these systems, the active catalyst is generated by a base-induced cyclometalation at the methyl group of this substituent to generate an iridium metalacycle bound by the COD ligand of the [Ir(COD)Cl]2 precursor and one additional labile dative ligand. Such complexes catalyze the reactions of linear allylic esters with alkylamines, arylamines, phenols, alcohols, imides, carbamates, ammonia, enolates and enolate equivalents, as well as typical stabilized carbon nucleophiles generated from malonates and cyanoesters. Iridium catalysts for enantioselective allylic substitution have also been generated from phosphorus ligands with substituents bound by heteroatoms, and an account of the studies of such systems, along with a description of the development of iridium catalysts is included.

  12. Transition metal-catalyzed functionalization of pyrazines

    NARCIS (Netherlands)

    Nikishkin, N.; Huskens, Jurriaan; Verboom, Willem

    2013-01-01

    Transition metal-catalyzed reactions are generally used for carbon–carbon bond formation on pyrazines and include, but are not limited to, classical palladium-catalyzed reactions like Sonogashira, Heck, Suzuki, and Stille reactions. Also a few examples of carbon–heteroatom bond formation in

  13. Transition metal-catalyzed functionalization of pyrazines

    NARCIS (Netherlands)

    Nikishkin, Nicolai I.; Huskens, Jurriaan; Verboom, Willem

    2013-01-01

    Transition metal-catalyzed reactions are generally used for carbon–carbon bond formation on pyrazines and include, but are not limited to, classical palladium-catalyzed reactions like Sonogashira, Heck, Suzuki, and Stille reactions. Also a few examples of carbon–heteroatom bond formation in pyrazine

  14. Rh-catalyzed linear hydroformylation of styrene

    NARCIS (Netherlands)

    Boymans, E.; Janssen, Michèle; Müller, Christian; Lutz, M.|info:eu-repo/dai/nl/304828971; Vogt, D.

    2012-01-01

    Usually the Rh-catalyzed hydroformylation of styrene predominantly yields the branched, chiral aldehyde. An inversion of regioselectivity can be achieved using strong π-acceptor ligands. Binaphthol-based diphosphite and bis(dipyrrolyl-phosphorodiamidite) ligands were applied in the Rh-catalyzed hydr

  15. Gold-catalyzed naphthalene functionalization

    Directory of Open Access Journals (Sweden)

    Iván Rivilla

    2011-05-01

    Full Text Available The complexes IPrMCl (IPr = 1,3-bis(diisopropylphenylimidazol-2-ylidene, M = Cu, 1a; M = Au, 1b, in the presence of one equiv of NaBAr'4 (Ar' = 3,5-bis(trifluoromethylphenyl, catalyze the transfer of carbene groups: C(RCO2Et (R = H, Me from N2C(RCO2Et to afford products that depend on the nature of the metal center. The copper-based catalyst yields exclusively a cycloheptatriene derivative from the Buchner reaction, whereas the gold analog affords a mixture of products derived either from the formal insertion of the carbene unit into the aromatic C–H bond or from its addition to a double bond. In addition, no byproducts derived from carbene coupling were observed.

  16. Advance in the Study on Determining and Removal of Nonylphenol Ethoxylates in Water%水中壬基酚聚氧乙烯醚的测定及去除方法研究进展

    Institute of Scientific and Technical Information of China (English)

    岳治杰; 李文岩

    2012-01-01

    Along with the ethoxylates becomes a hot mine the concentration of as pretreatment technique. dangers of endocrine disruptors getting peopleg attention, research of water treatment. GC - MS and HPLC are now the study on nonylphenol mainly applied to deter- nonylphenol ethoxylates in water samples, and solid phase extraction (SPE) is used The deep treatment process such as activated carbons and resin adsorption, photo- decomposition and biodegradation which paid much attention to in recent years show effective decomposition of nonylphenol ethoxylates in water.%随着内分泌干扰物的危害不断得到人们的重视,壬基酚聚氧乙烯醚的研究成为了水处理的热点。目前检测水样中壬基酚聚氧乙烯醚的主要方法是采用GC-MS和HPLC,预处理主要采用固相萃取。近年来倍受关注的深度处理工艺如活性炭、树脂吸附法,以及光催化降解和生物降解法能有效的去除水中的壬基酚聚氧乙烯醚。

  17. Pt-catalyzed ozonation of aqueous phenol solution using high-gravity rotating packed bed.

    Science.gov (United States)

    Chang, Chia-Chi; Chiu, Chun-Yu; Chang, Ching-Yuan; Chang, Chiung-Fen; Chen, Yi-Hung; Ji, Dar-Ren; Tseng, Jyi-Yeong; Yu, Yue-Hwa

    2009-09-15

    In this study, a high-gravity rotating packed bed (HGRPB or HG) was used as a catalytic ozonation (Cat-OZ) reactor to decompose phenol. The operation of HGRPB system was carried out in a semi-batch apparatus which combines two major parts, namely the rotating packed bed (RPB) and photo-reactor (PR). The high rotating speed of RPB can give a high volumetric gas-liquid mass transfer coefficient with one or two orders of magnitude higher than those in the conventional packed beds. The platinum-containing catalyst (Dash 220N, Pt/gamma-Al(2)O(3)) and activated alumina (gamma-Al(2)O(3)) were packed in the RPB respectively to adsorb molecular ozone and the target pollutant of phenol on the surface to catalyze the oxidation of phenol. An ultra violet (UV) lamp (applicable wavelength lambda=200-280 nm) was installed in the PR to enhance the self-decomposition of molecular ozone in water to form high reactive radical species. Different combinations of advanced oxidation processes (AOPs) with the HGRPB for the degradation of phenol were tested. These included high-gravity OZ (HG-OZ), HG catalytic OZ (HG-Cat-OZ), HG photolysis OZ (HG-UV-OZ) and HG-Cat-OZ with UV (HG-Cat-UV-OZ). The decomposition efficiency of total organic compound (eta(TOC)) of HG-UV-OZ with power of UV (P(UV)) of 16W is 54% at applied dosage of ozone per volume sample m(A,in)=1200 mg L(-1) (reaction time t=20 min), while that of HG-OZ without the UV irradiation is 24%. After 80 min oxidation (m(A,in)=4800 mg L(-1)), the eta(TOC) of HG-UV-OZ is as high as 94% compared to 82% of HG-OZ process. The values of eta(TOC) for HG-Cat-OZ process with m(S)=42 g are 56% and 87% at m(A,in)=1200 and 4800 mg L(-1), respectively. By increasing the catalyst mass to 77 g, the eta(TOC) for the HG-Cat-OZ process reaches 71% and 90% at m(A,in)=1200 and 4800 mg L(-1), respectively. The introduction of Pt/gamma-Al(2)O(3) as well as UV irradiation in the HG-OZ process can enhance the eta(TOC) of phenol significantly, while gamma

  18. 乙氧基化对表面活性剂最终生物降解性能的影响%Effect of ethoxylation on ultimate biodegradability of surfactants

    Institute of Scientific and Technical Information of China (English)

    张广良; 冯瑜; 李国晋; 宋鹏

    2014-01-01

    采用CO2气体溢出法研究了乙氧基化对非离子及阳离子表面活性剂最终生物降解性能的影响。结果表明,对于非离子表面活性剂APG与对应的AEG,经过乙氧基化后的AEG最终生物降解率较APG略有升高;对于阳离子表面活性剂二硬脂酸乙酯基甲基硫酸甲酯铵(2C17EQDMS)与对应的乙氧基化二硬脂酸乙酯基羟乙基甲基硫酸甲酯铵(2C17EQDMS-3EO),2C17EQDMS-3EO的最终生物降解率较2C17EQDMS也略有升高;对于三硬脂酸乙酯基甲基硫酸甲酯铵(3C17EQDMS)及对应的乙氧基化三硬脂酸乙酯基甲基硫酸甲酯铵(3C17EQDMS-nEO),3C17EQDMS-nEO的最终生物降解率较3C17EQDMS下降,并且随着EO链的增加,最终生物降解率呈下降趋势。%The effect of ethoxylation on ultimate biodegradability of surfactants was studied by CO2 evolu⁃tion method. The results showed that for nonionic surfactants alkyl polyglycosides (APG) and the correspond⁃ing AEG, after ethoxylation the ultimate biodegradability of AEG was increased slightly compared with APG;for anionic surfactants di-stearic acid methyl ammonium methylsulfate (2C17EQDMS) and the corresponding ethoxylated di-stearic acid hydroxyethyl methyl ammonium methylsulfate (2C17EQDMS-3EO), after ethoxyl⁃ation the ultimate biodegradability of 2C17EQDMS-3EO was also increased compared with 2C17EQDMS; but for tri-stearic acid methyl ammonium methylsulfate (3C17EQDMS) and the corresponding ethoxylated tri-stea⁃ric acid methyl ammonium methylsulfate 3C17EQDMS-nEO, after ethoxylation the ultimate biodegradability of 3C17EQDMS-nEO was decreased, and with the increase of EO chains, the biodegradability was on the decline.

  19. Advances in lipase-catalyzed esterification reactions.

    Science.gov (United States)

    Stergiou, Panagiota-Yiolanda; Foukis, Athanasios; Filippou, Michalis; Koukouritaki, Maria; Parapouli, Maria; Theodorou, Leonidas G; Hatziloukas, Efstathios; Afendra, Amalia; Pandey, Ashok; Papamichael, Emmanuel M

    2013-12-01

    Lipase-catalyzed esterification reactions are among the most significant chemical and biochemical processes of industrial relevance. Lipases catalyze hydrolysis as well as esterification reactions. Enzyme-catalyzed esterification has acquired increasing attention in many applications, due to the significance of the derived products. More specifically, the lipase-catalyzed esterification reactions attracted research interest during the past decade, due to an increased use of organic esters in biotechnology and the chemical industry. Lipases, as hydrolyzing agents are active in environments, which contain a minimum of two distinct phases, where all reactants are partitioned between these phases, although their distribution is not fixed and changes as the reaction proceeds. The kinetics of the lipase-catalyzed reactions is governed by a number of factors. This article presents a thorough and descriptive evaluation of the applied trends and perspectives concerning the enzymatic esterification, mainly for biofuel production; an emphasis is given on essential factors, which affect the lipase-catalyzed esterification reaction. Moreover, the art of using bacterial and/or fungal strains for whole cell biocatalysis purposes, as well as carrying out catalysis by various forms of purified lipases from bacterial and fungal sources is also reviewed.

  20. Degradation of chlorophenols and alkylphenol ethoxylates, two representative textile chemicals, in water by advanced oxidation processes: the state of the art on transformation products and toxicity.

    Science.gov (United States)

    Karci, Akin

    2014-03-01

    Advanced oxidation processes based on the generation of reactive species including hydroxyl radicals are viable options in eliminating a wide array of refractory organic contaminants in industrial effluents. The assessment of transformation products and toxicity should be, however, the critical point that would allow the overall efficiency of advanced oxidation processes to be better understood and evaluated since some transformation products could have an inhibitory effect on certain organisms. This article reviews the most recent studies on transformation products and toxicity for evaluating advanced oxidation processes in eliminating classes of compounds described as "textile chemicals" from aqueous matrices and poses questions in need of further investigation. The scope of this paper is limited to the scientific studies with two classes of textile chemicals, namely chlorophenols and alkylphenol ethoxylates, whose use in textile industry is a matter of debate due to health risks to humans and harm to the environment. The article also raises the critical question: What is the state of the art knowledge on relationships between transformation products and toxicity?

  1. Effect of a commercial alcohol ethoxylate surfactant (C11-15E7) on biodegradation of phenanthrene in a saline water medium by Neptunomonas naphthovorans.

    Science.gov (United States)

    Li, Jing-Liang; Bai, Renbi

    2005-02-01

    Biodegradation of poorly soluble polycyclic aromatic hydrocarbons (PAHs) has been a challenge in bioremediation. In recent years, surfactant-enhanced bioremediation of PAH contaminants has attracted great attention in research. In this study, biodegradation of phenanthrene as a model PAHs solubilized in saline micellar solutions of a biodegradable commercial alcohol ethoxylate nonionic surfactant was investigated. The critical micelle concentration (CMC) of the surfactant and its solubilization capacity for phenanthrene were examined in an artificial saline water medium, and a type of marine bacteria, Neptunomonas naphthovorans, was studied for the biodegradation of phenanthrene solubilized in the surfactant micellar solutions of the saline medium. It is found that the solubility of phenanthrene in the surfactant micellar solutions increased linearly with the surfactant concentrations, but, at a fixed phenanthrene concentration, the biodegradability of phenanthrene in the micellar solutions decreased with the increase of the surfactant concentrations. This was attributed to the reduced bioavailability of phenanthrene, due to its increased solubilization extent in the micellar phase and possibly lowered mass transfer rate from the micellar phase into the aqueous phase or into the bacterial cells. In addition, an inhibitory effect of the surfactant on the bacterial growth at high surfactant concentrations may also play a role. It is concluded that the surfactant largely enhanced the solubilization of phenanthrene in the saline water medium, but excess existence of the surfactant in the medium should be minimized or avoided for the biodegradation of phenanthrene by Neptunomonas naphthovorans.

  2. Study on Separation of Alkylphenol Ethoxylates in Different Liquid Chromatography Modes%烷基酚聚氧乙烯醚在不同液相色谱分离模式中的分离研究

    Institute of Scientific and Technical Information of China (English)

    马强; 王超; 白桦; 王星; 张庆; 肖海清; 闫妍; 董益阳; 王宝麟

    2009-01-01

    考察了烷基酚聚氧乙烯醚在反相色谱、正相键合色谱、硅胶吸附色谱、体积排阻色谱4种不同液相色谱分离模式中的分离效果,分别采用Kromasil C_(18)(250 mm× 4.6 mm,5 μm)、Agilent ZORBAX NH_2(250 mm× 4.6 mm,5 μm)、Waters Spherisorb S3W(150 mm×2.0 mm,3 μm)和Shodex MSpak GF-310 2D(150 mm×2.0 mm,5 μm)色谱柱,以225 nm为紫外检测波长,对不同液相色谱分离模式的流动相组成、梯度洗脱条件、柱温、流速等进行了优化,并对烷基酚聚氧乙烯醚在不同液相色谱分离模式中的保留机理进行了初步探讨.结果表明,正相键合色谱实现了烷基酚聚氧乙烯醚的最佳分离;硅胶吸附色谱和体积排阻色谱的分离效果较正相键合色谱稍差.%The separation effects of alkylphenol ethoxylates in different liquid chromatography modes, such as reversed-phase liquid chromatography, bonded normal-phase liquid chromatography, silica adsorption chromatography and size exclusion chromatography were investigated. The chromatographic columns including Kromasil C_(18)(250 mm × 4.6 mm, 5 μm) , Agilent ZORBAX NH_2(250 mm × 4.6 mm, 5 μm), Waters Spherisorb S3W(150 mm × 2.0 mm, 3 μm) and Shodex MSpak GF-310 2D( 150 mm × 2. 0 mm, 5 μm) were utilized and detection wavelength was set at 225 nm. The chro-matographic conditions, including mobile phase composition, gradient elution, column temperature, flow rate, etc, were optimized. The retention mechanism of alkylphenol ethoxylates in different liq-uid chromatography modes was discussed. The best resolution of alkylphenol ethoxylates was achieved by bonded normal-phase liquid chromatography, which was slightly better than the resolution in silica adsorption chromatography and size exclusion chromatography. However, the reversed-phase mobile phase in silica adsorption chromatography and size exclusion chromatography possessed excellent com-patibility with ESI mass spectrometry. Both the structural information of

  3. 脂肪酸甲酯乙氧基化物的生产工艺及性能研究%Study on Production Process and Properties of Fatty Acid Methyl Ester Ethoxylates

    Institute of Scientific and Technical Information of China (English)

    刘伟

    2015-01-01

    Production condition of fatty acid methyl ester ethoxylates at home and abroad was introduced, and its production process and properties were discussed, application prospect of MEE was analyzed.%论述了国内外脂肪酸甲酯乙氧基化物的现状,主要对其生产工艺、产品性能进行了分析讨论,并在此基础上对其应用前景进行了阐述。

  4. Two Ethoxylation Techniques and Their Influences on Performance of Alcohol Ether%两种乙氧基化技术及其对醇醚性能的影响

    Institute of Scientific and Technical Information of China (English)

    刘伟

    2016-01-01

    The present situation, advantages and disadvantages of the two ethoxylation technique were introduced. The Press and HH technique influence on EO distribution of AEO2 and PEG content were discussed.%简要介绍了国内两种主要乙氧基化技术的现状及其优缺点,并对Press技术和HH技术对AEO2中的EO分布、PEG含量的影响进行了分析讨论。

  5. Enantioselective, iridium-catalyzed monoallylation of ammonia.

    Science.gov (United States)

    Pouy, Mark J; Stanley, Levi M; Hartwig, John F

    2009-08-19

    Highly enantioselective, iridium-catalyzed monoallylations of ammonia are reported. These reactions occur with electron-neutral, -rich, and -poor cinnamyl carbonates, alkyl and trityloxy-substituted allylic carbonates, and dienyl carbonates in moderate to good yields and excellent enantioselectivities. This process is enabled by the use of an iridium catalyst that does not require a Lewis acid for activation and that is stable toward a large excess of ammonia. This selective formation of primary allylic amines allows for one-pot syntheses of heterodiallylamines and allylic amides that are not otherwise accessible via iridium-catalyzed allylic amination without the use of blocking groups and protective group manipulations.

  6. Attractor Explosions and Catalyzed Vacuum Decay

    Energy Technology Data Exchange (ETDEWEB)

    Green, Daniel; Silverstein, Eva; Starr, David

    2006-05-05

    We present a mechanism for catalyzed vacuum bubble production obtained by combining moduli stabilization with a generalized attractor phenomenon in which moduli are sourced by compact objects. This leads straightforwardly to a class of examples in which the Hawking decay process for black holes unveils a bubble of a different vacuum from the ambient one, generalizing the new endpoint for Hawking evaporation discovered recently by Horowitz. Catalyzed vacuum bubble production can occur for both charged and uncharged bodies, including Schwarzschild black holes for which massive particles produced in the Hawking process can trigger vacuum decay. We briefly discuss applications of this process to the population and stability of metastable vacua.

  7. Proliferation inhibition effects of ethoxylated fatty alcohol on cells%脂肪醇聚氧乙烯醚对细胞的增殖抑制影响

    Institute of Scientific and Technical Information of China (English)

    陈晓伟; 王晓宁; 龚龑; 廖青

    2011-01-01

    In view of the safety problem of chemicals for textiles, MTT assay was adopted to study the effects of three different kinds of ethoxylated fatty alcohols on the proliferation inhibition of Chinese hamster ovary ( CHO ) cells and human cervical carcinoma HeLa cells. The results indicated that the proliferation inhibition effect of ethoxylated fatty alcohol on both CHO cells and HeLa cells gradually decreased as the number of EO increased. In other words, with respect to the proliferation inhibition on both cells, it showed the following order; AEO5 > AEO9 > AE015. When the concentrations of AE05 and AE09 were higher than 0. 050 μL/mL and 0. 075 μL/mL, respectively, the increase of proliferation inhibition effect on the cells exhibited insignificant with the increase of the concentration. However, when the concentration of AEO15 was higher than 0. 100 μL/mL, its proliferation inhibition effect on the cells still showed an upward tend. When the concentrations of AE05, AEO9 and AEO15 were lower than 0.005, 0.005 and 0.010 μL/mL, respectively, their proliferation inhibition effect on CHO cells and HeLa cells was not noticeable.%针对纺织用化学品安全问题,采用噻唑蓝(MTT)比色法研究了脂肪醇聚氧乙烯醚系列表面活性剂对中华仓鼠卵巢CHO细胞及人体宫颈癌HeLa细胞增殖抑制情况.结果表明:随着环氧乙烷(EO)数量的增加,脂肪醇聚氧乙烯醚对CHO细胞及HeLa细胞增殖抑制率均逐渐减小,脂肪醇聚氧乙烯醚AEO5对2种细胞增殖抑制率最大,AEO9次之,AEO15最小;AEO5浓度大于0.050 μL/mL时,细胞增殖抑制率随浓度增大变化不明显,AEO9浓度大于0.075 μL/mL时,细胞增殖抑制率随浓度增大变化不明显,而AEO15浓度为0.100 μL/mL时,对细胞增殖抑制率仍呈现上升趋势.AEO5、AEO9和AEO15浓度分别低于0.005、0.005、0.010 μL/mL时,对CHO细胞及HeLa细胞增殖无明显抑制.

  8. Reversible and Irreversible Adsorption Energetics of Poly(ethylene glycol) and Sorbitan Poly(ethoxylate) at a Water/Alkane Interface.

    Science.gov (United States)

    Huston, Kyle J; Larson, Ronald G

    2015-07-14

    We simulate poly(ethylene glycol) (PEG) oligomers and model Tween 80 (polyoxyethylene sorbitan monooleate) molecules at water/alkane interfaces. Using the weighted histogram analysis method (WHAM), including an extension of WHAM to two reaction coordinates to remove hysteresis, we calculate interfacial potentials of mean force (PMFs) for PEG and Tween 80 using three force fields: the atomistic GROMOS 53a6OXY+D and two coarse-grained (CG) MARTINI force fields. Because the force fields have not yet been validated for PEO adsorption to hydrophobic interfaces, we calculate PMFs for alcohol ethoxylates C12E2 and C12E8 and find that they agree with semiempirical results of Mulqueen and Blankschtein [Langmuir 2002, 18 (2), 365-376] for the GROMOS 53a6OXY+D force field, whereas for both MARTINI force fields, PEO adsorbs too weakly to a clean hydrophobic interface. One MARTINI force field incorrectly shows depletion rather than adsorption to a clean hydrophobic interface. We find that the adsorption free energy for PEG oligomers at a clean, planar water/alkane interface is around 1.3 kBT per monomer for the atomistic force field but is less than half of this for the two CG force fields. With the newly validated GROMOS 53a6OXY+D force field, we bracket the dilute adsorption free energy for a model Tween 80 molecule at the clean water/squalane interface. We also calculate the pressure-area isotherm. We exploit these data with the Nikas-Mulqueen-Blankschtein (NMB) theory and a simple transport model to demonstrate a transition from irreversible to reversible adsorption with increasing surface coverage, consistent with experimental results of Reichert and Walker [Langmuir 2013, 29 (6), 1857-1867].

  9. Polymer monolith microextraction using poly(butyl methacrylate-co-1,6-hexanediol ethoxylate diacrylate) monolithic sorbent for determination of phenylurea herbicides in water samples.

    Science.gov (United States)

    Lin, Shu-Ling; Wu, Yu-Ru; Fuh, Ming-Ren

    2016-01-15

    In this study, recently developed 1,6-hexanediol ethoxylate diacrylate (HEDA)-based polymeric monoliths were utilized as sorbents for efficient extraction of phenylurea herbicides (PUHs) from water samples. The HEDA-based monolithic sorbents were prepared in a fused silica capillary (0.7mm i.d., 4.5-cm long) for polymer monolith microextraction (PMME). The experimental parameters of PMME microextraction including sample loading speed, pH of sample solution, composition of elution solvent, and addition of salt were optimized to efficiently extract PUHs from environmental water samples. The extracted PUHs were determined using ultra-high performance liquid chromatography (UHPLC) with UV-photodiode array detection. The extraction recoveries for PUHs-spiked water samples were 91.1-108.1% with relative standard deviations lower than 5%. The linearity range was 0.025-25ngmL(-1) for each PUH and the detection limits of PUHs were estimated at 0.006-0.019ng mL(-1). In addition, good intra-day/inter-day precision (0.1-8.7%/0.2-8.9%) and accuracy (92.0-108.0%/96.5-105.2%) of the proposed method were obtained. The extraction capacity of the monolith-filled capillary was also determined to be approximately 1μg. Moreover, each monolith-filled capillary could be reused up to 8 times without carry-over. According to the European Union regulations, the allowed permissible limit of any single herbicide in drinking water is 0.1ng mL(-1). This permissible level fell in the linear range examined in this study. In addition, the proposed method provided detection limits lower than the allowed permissible level, which demonstrated the feasibility of utilizing the HEDA-based monolithic sorbent to perform PMME for determining contaminants, such as PUHs, in environmental application.

  10. Synthesis, characterization and photocatalytic activity of ZnO flower and pseudo-sphere: Nonylphenol ethoxylate degradation under UV and solar irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ashar, Ambreen [Department of Chemistry, University of Agriculture, Faisalabad 38040 (Pakistan); Iqbal, Munawar, E-mail: bosalvee@yahoo.com [Department of Chemistry, Qurtuba University of Science and Information Technology, Peshawar 25100, KPK (Pakistan); Bhatti, Ijaz Ahmad; Ahmad, Muhammad Zubair; Qureshi, Khizar [Department of Chemistry, University of Agriculture, Faisalabad 38040 (Pakistan); Nisar, Jan [National Centre of Excellence in Physical Chemistry, University of Peshawar, Peshawar 25120 (Pakistan); Bukhari, Iftikhar Hussain [Department of Chemistry, Government College University, Faisalabad (Pakistan)

    2016-09-05

    ZnO particles (flower and pseudo sphere) were synthesized via precipitation route and characterized using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX), Fourier transform infra-red (FTIR) spectroscopy, Atomic force microscopy (AFM), Particle size analyzer and UV–visible techniques. The photocatalytic activities (PCA) of ZnO flower (uncalcined) and pseudo-sphere (calcined) were evaluated by degrading nonylphenol ethoxylate-9 (NP9EO) under UV and solar irradiation. The process variables i.e., catalyst dose, calcination temperature, H{sub 2}O{sub 2} concentration, pH and UV/solar light exposure were investigated and under optimum conditions of process variables, paper, textile and leather industries effluents were also treated. Calcination at high temperature affected the morphology of ZnO particles. Both ZnO flower and pseudo-sphere degraded NP9EO and pollutants in industrial wastewater efficiently under both UV and solar irradiation. Maximum NP9EO degradation was achieved at 2.5 g/L catalyst dose, high calcination temperature, 4% H{sub 2}O{sub 2} concentration, 6 pH, 110 UV exposure and 12 h solar light exposure. Results reveal that ZnO is efficient photo-catalyst and could be used under solar irradiation for photocatalytic application by tuning the band gap. - Highlights: • ZnO flower and pseudo-spheres were synthesized via precipitation route. • The photocatalytic activities by degrading surfactant. • ZnO particles showed considerable photocatalytic activity under UV and solar irradiation. • By tuning the band gap of ZnO absorption capacity can be enhanced.

  11. In vitro biotransformation of surfactants in fish. Part I: linear alkylbenzene sulfonate (C12-LAS) and alcohol ethoxylate (C13EO8).

    Science.gov (United States)

    Dyer, Scott D; Bernhard, Mary Jo; Cowan-Ellsberry, Christina; Perdu-Durand, Elisabeth; Demmerle, Susanne; Cravedi, Jean-Pierre

    2008-06-01

    Developing regulatory activities (e.g., REACh, [DGEE. 2003. Directorates General Enterprise and Environment. The new EU chemicals legislation REACH. DG Enterprise, Brussels, Belgium. (http://www.europa.eu.int/comm/enterprise/reach/index_en.htm)]) will require bioaccumulation to be assessed for thousands of chemicals. Further, there is increasing pressure to reduce, refine or replace animal tests. Given this scenario, there is an urgent need to evaluate the feasibility of in vitro systems to supply data useful for bioaccumulation estimation. Subcellular and cellular hepatic systems were tested to determine the biotransformation of two surfactants: C12-2-LAS (2-phenyl dodecane p-sulfonate) and an alcohol ethoxylate C13EO8 (Octaethylene glycol monotridecyl ether). The subcellular systems tested were liver homogenates and microsomes from the common carp (Cyprinus carpio) and rainbow trout (Oncorhynchus mykiss). Cellular systems consisted of primary hepatocytes from the common carp (Cyprinus carpio) and PLHC-1 cells, hepatocarcinoma cells from the desert topminnow (Poeciliopsis lucida). All in vitro systems were exposed to radiolabeled test compounds and assayed for biotransformation using liquid scintillation and thin layer chromatographic methods. First-order kinetics were used to estimate rates of biotransformation. Bioconcentration of test materials in fish were predicted using an in vitro to in vivo metabolic rate extrapolation model linked to a mass-balance model commonly used to predict bioaccumulation in fish. Subcellular biotransformation rates for each of the surfactants were greatest with microsomes. Cellular loss rates exceeded subcellular rates, leading to lower predicted BCF values. Predicted BCFs corresponded closely to measured values in several fish species, verifying the utility of in vitro systems in refining Kow-only-based BCFs via the inclusion of biotransformation rates.

  12. Palladium catalyzed hydrogenation of bio-oils and organic compounds

    Science.gov (United States)

    Elliott, Douglas C.; Hu, Jianli; Hart, Todd R.; Neuenschwander, Gary G.

    2008-09-16

    The invention provides palladium-catalyzed hydrogenations of bio-oils and certain organic compounds. Experimental results have shown unexpected and superior results for palladium-catalyzed hydrogenations of organic compounds typically found in bio-oils.

  13. Rhodium-catalyzed restructuring of carbon frameworks.

    Science.gov (United States)

    Murakami, Masahiro

    2010-10-01

    Metal-catalyzed reactions involving an elementary step which cleaves a carbon-carbon bond provide unique organic transformations. Restructuring reactions recently developed in our laboratory, through which the carbon framework of a starting substance is restructured into a totally different carbon framework, are discussed, with the possibility of applying such methods to the synthesis of natural products.

  14. Zeolite 5A Catalyzed Etherification of Diphenylmethanol

    Science.gov (United States)

    Cooke, Jason; Henderson, Eric J.; Lightbody, Owen C.

    2009-01-01

    An experiment for the synthetic undergraduate laboratory is described in which zeolite 5A catalyzes the room temperature dehydration of diphenylmethanol, (C[subscript 6]H[subscript 5])[subscript 2]CHOH, producing 1,1,1',1'-tetraphenyldimethyl ether, (C[subscript 6]H[subscript 5])[subscript 2]CHOCH(C[subscript 6]H[subscript 5])[subscript 2]. The…

  15. Lysophosphatidylcholine synthesis by lipase-catalyzed ethanolysis.

    Science.gov (United States)

    Yang, Guolong; Yang, Ruoxi; Hu, Jingbo

    2015-01-01

    Lysophosphatidylcholine (LPC) is amphiphilic substance, and possesses excellent physiological functions. In this study, LPC was prepared through ethanolysis of phosphatidylcholine (PC) in n-hexane or solvent free media catalyzed by Novozym 435 (from Candida antarctica), Lipozyme TLIM (from Thermomcyces lanuginosus) and Lipozyme RMIM (from Rhizomucor miehei). The results showed that three immobilized lipases from Candida Antarctica, Thermomcyces lanuginosus and Rhizomucor miehei could catalyze ethanolysis of PC efficiently. In n-hexane, the LPC conversions of ethanolysis of PC catalyzed by Novozyme 435, Lipozyme TLIM and Lipozyme RMIM could reach to 98.5 ± 1.6%, 94.6 ± 1.4% and 93.7 ± 1.8%, respectively. In solvent free media, the highest LPC conversions of ethanolysis of PC catalyzed by Novozyme 435, Lipozyme TL IM and Lipozyme RM IM were 97.7 ± 1.7%, 93.5 ± 1.2% and 93.8 ± 1.9%, respectively. The catalytic efficiencies of the three lipases were in the order of Novozyme 435 > Lipozyme TLIM > Lipozyme RMIM. Furthermore, their catalytic efficiencies in n-hexane were better than those in solvent free media.

  16. Mechanochemical ruthenium-catalyzed olefin metathesis.

    Science.gov (United States)

    Do, Jean-Louis; Mottillo, Cristina; Tan, Davin; Štrukil, Vjekoslav; Friščić, Tomislav

    2015-02-25

    We describe the development of a mechanochemical approach for Ru-catalyzed olefin metathesis, including cross-metathesis and ring-closing metathesis. The method uses commercially available catalysts to achieve high-yielding, rapid, room-temperature metathesis of solid or liquid olefins on a multigram scale using either no or only a catalytic amount of a liquid.

  17. Pinacol Coupling Reactions Catalyzed by Active Zinc

    Institute of Scientific and Technical Information of China (English)

    Hui ZHAO; Wei DENG; Qing Xiang GUO

    2005-01-01

    Pinacol coupling reactions catalyzed by active zinc revealed high activity and extensive suitability. The efficiency of the reaction was improved apparently owing to decreasing reductive potential of zinc. In addition, the results indicated that the zinc activity has a direct relation to the coupling reactivity compared to untreated zinc or other general active zinc.

  18. Catalyzing curriculum evolution in graduate science education.

    Science.gov (United States)

    Gutlerner, Johanna L; Van Vactor, David

    2013-05-09

    Strategies in life science graduate education must evolve in order to train a modern workforce capable of integrative solutions to challenging problems. Our institution has catalyzed such evolution through building a postdoctoral Curriculum Fellows Program that provides a collaborative and scholarly education laboratory for innovation in graduate training.

  19. Biodiesel production by enzyme-catalyzed transesterification

    Directory of Open Access Journals (Sweden)

    Stamenković Olivera S.

    2005-01-01

    Full Text Available The principles and kinetics of biodiesel production from vegetable oils using lipase-catalyzed transesterification are reviewed. The most important operating factors affecting the reaction and the yield of alkyl esters, such as: the type and form of lipase, the type of alcohol, the presence of organic solvents, the content of water in the oil, temperature and the presence of glycerol are discussed. In order to estimate the prospects of lipase-catalyzed transesterification for industrial application, the factors which influence the kinetics of chemically-catalysed transesterification are also considered. The advantages of lipase-catalyzed transesterification compared to the chemically-catalysed reaction, are pointed out. The cost of down-processing and ecological problems are significantly reduced by applying lipases. It was also emphasized that lipase-catalysed transesterification should be greatly improved in order to make it commercially applicable. The further optimization of lipase-catalyzed transesterification should include studies on the development of new reactor systems with immobilized biocatalysts and the addition of alcohol in several portions, and the use of extra cellular lipases tolerant to organic solvents, intracellular lipases (i.e. whole microbial cells and genetically-modified microorganisms ("intelligent" yeasts.

  20. Palladium-Catalyzed Intramolecular Aminofluorination of Styrenes%Palladium-Catalyzed Intramolecular Aminofluorination of Styrenes

    Institute of Scientific and Technical Information of China (English)

    徐涛; 邱水发; 刘国生

    2011-01-01

    A novel palladium-catalyzed intramolecular oxidative aminofluorination of styrenes has been developed by using NFSI as fluorinating reagent. This reaction represented an efficient method for the synthesis of 2-aryl-3-fluoropyrrolidine derivatives.

  1. Kinetics of aggregation growth with competition between catalyzed birth and catalyzed death

    Institute of Scientific and Technical Information of China (English)

    Wang Hai-Feng; Lin Zhen-Quan; Gao Yan

    2008-01-01

    An aggregation growth model of three species A, B and C with the competition between catalyzed birth and catalyzed death is proposed. Irreversible aggregation occurs between any two aggregates of the like species with the constant rate kernels In(n = 1, 2, 3). Meanwhile, a monomer birth of an A species aggregate of size k occurs under the catalysis of a B species aggregate of size j with the catalyzed birth rate kernel K(k,j) = Kkjv, and a monomer death of an A species aggregate of size k occurs under the catalysis of a C species aggregate of size j with the catalyzed death rate kernel L(k, j) = Lkjv, where v is a parameter reflecting the dependence of the catalysis reaction rates of birth and death on the size of catalyst aggregate. The kinetic evolution behaviours of the three species are investigated by the rate equation approach based on the mean-field theory. The form of the aggregate size distribution of A species ak(t) is found to be dependent crucially on the competition between the catalyzed birth and death of A species, as well as the irreversible aggregation processes of the three species: (1) In the v < 0 case, the irreversible aggregation dominates the process, and ak(t) satisfies the conventional scaling form; (2) In the v ≥ 0 case, the competition between the catalyzed birth and death dominates the process. When the catalyzed birth controls the process, ak(t) takes the conventional or generalized scaling form. While the catalyzed death controls the process, the scaling description of the aggregate size distribution breaks down completely.

  2. Comparative Study of Ozonation and Catalyzed Ozonation Processes for Drinking Water Treatment by Pilot Test

    Institute of Scientific and Technical Information of China (English)

    GUAN Chun-yu; MA Jun; SHI Feng-hua; ZHANG Xiao-lan

    2009-01-01

    The ozone consumption effect and organic removal ability of metal coated cordierite ceramic honeycombs catalytic ozonation (catazone) process and ozonation process were comparatively studied by pilot-scale experiments. By Scan Electron Microscope (SEM), Atomic Force Microscope (AFM), BET, and X-ray photoelectron spectroscopy (XPS) analysis, metal oxides attached to ceramic surface were found to be in the form of crystal cluster, and the pore structure of ceramics was less developed. The air flow statuses of vacant catazone and ozone contactors were inclined to be plug-flow and mixed flow, respectively. Comparing with ozonation process, the ozone mass transfer efficiency of catazone process is lower, and the ozone decomposition efficiency of catazone is higher. The former effect is more obvious in semi-batch experiment, and the latter effect is more obvious in continuous-flow experiment. Unsaturated organics removal efficiencies of the two oxidation processes are similar, and are less affected by dissolved ozone concentration when it is higher than 1 mg/L. More dissolved organics were detected in catazone process in continuous-flow reaction, and more CH3Cl3formation potential (CH3Cl3FP) was removed by catazone in semi-batch mode, especially in the water with lower UV254.

  3. Influence of rapid development of EO plant for downstream ethoxylation industry%环氧乙烷迅猛发展对下游乙氧基化装置格局的影响

    Institute of Scientific and Technical Information of China (English)

    黄朝兵

    2012-01-01

    随着环氧乙烷项目的迅猛发展,其与日增多的产量很大程度上缓解了市场的需求。同时,这种快速增长的形势对其下游产品更深更广的发展将起到重要的直接推动作用,目前环氧乙烷下游产品逐渐集中在乙醇胺系列、聚乙二醇系列、传统的AEO和TX系列以及新兴的减水剂系列等。通过对当前乙氧基化项目情况的分析,预测未来乙氧基化的发展格局。%The rapid growth of EO projects and increasing output promoted the development of" downstream products to some extent. At present, EO downstream products are mainly focused on ethanolamine, polyethylene glycol, traditional AEO, TX series as well as newly developed water reducing agent. This article analyzed current ethoxylation projects and predicted the future development of ethoxylation industry.

  4. 窄分布脂肪醇聚氧乙烯醚在清洗中替代壬基酚聚氧乙烯醚的可行性探讨%Possibility Research on Replacement of Nonylphenol Ethoxylates by Narrow Range Ethoxylates in Cleaning Application

    Institute of Scientific and Technical Information of China (English)

    姚永丽; 刘津南; 黄甦萍; 大鹏

    2016-01-01

    本文介绍了NRE(窄分布脂肪醇聚氧乙烯醚)的性能,并就含NRE的Berol 609的低温流动性、溶解速度、凝胶范围、泡沫性能、润湿性和去污力进行了测试,并和NPE-9、NPE-10及常用来替代NPE的AEO-9进行了比较,结果显示:Berol 609的后两者性能与NPE-9类似,其他性能优于NPE-9,因此,Berol 609在清洗中完全有可能替代NPE-9。%The properties and performances of NRE (narrow range ethoxylates) are introduced in this article. Furthermore, Berol 609 which contains part of NRE is mainly studied. Some of its properties, including low temperature fluidity, dissolution property, gel property, foaming property, wetting property and cleaning effect, are tested and compared with NPE-9, NPE-10 and AEO-9 (the common replacement of NPE). The results demonstrate that the latter two properties of Berol 609 are similar with NPE-9 and other properties are better than NPE-9. So Berol 609 is an ideal replacement of NPE-9.

  5. Safety enhancement by transposition of the nitration of toluene from semi-batch reactor to continuous intensified heat exchanger reactor

    OpenAIRE

    Di Miceli Raimondi, Nathalie; Olivier Maget, Nelly; Gabas, Nadine; Cabassud, Michel; GOURDON, Christophe

    2015-01-01

    International audience; The behaviour of a continuous intensified heat exchanger (HEX) reactor in case of process failure is analysed and compared to the behaviour of a semi-continuous reactor. The nitration of toluene is considered as test reaction to identify the main failure scenarios that can lead to thermal runaway in both processes using the HAZOP method.No flow rate of process fluid and utility fluid in the continuous process. No stirring during feeding of the reactor followed by norma...

  6. Two step, PID and model predictive control using artificial neural network applied on semi-batch reactor

    OpenAIRE

    Macků, Lubomír; Sámek, David

    2010-01-01

    Článek se zabývá řízením polodávkového reaktoru používaného v procesu recyklace chromitého odpadu enzymatickou hydrolýzou. Chromitý odpad pochází z procesu chromočinění při zpracování přírodní kůže. Recyklační technika odděluje chrom od proteinu ve formě chromitého filtračního koláče. Všechny produkty tohoto procesu jsou dále využitelné, jedná se tedy o bezodpadní technologii. V reaktoru dochází k opakovanému využití chromitého kalu (chromitého filtračního koláče). Regulace polodávkového reak...

  7. Determination of Alkylphenol Ethoxylates in Leather and Textile by GC-MS%皮革及纺织品中APEO残留量的GC-MS测定

    Institute of Scientific and Technical Information of China (English)

    马贺伟; 赵立国; 洪新球; 黄新霞

    2011-01-01

    A procedure was developed for determining alkylphenol ethoxylates (APEOn) in leather and textile by gas chromatography - mass detector. The targets were extracted from samples using ultrasonic -assisted acetonitrile extraction. APEOn in the extracts were first converted into AP with aluminum triiodide as cleavage reagent, and the yielded AP were then isolated and detected by GC - MS. The contents of APEOn were calculated by normalizing to APEO9. For the total procedure, the recovery ranged from 91% to 101% and the precision (RSD%) ranged from 5% ~9%. The quantitative detection limits are 2.5mg/kg and 1.2mg/kg for NPEO9 and OPEO9, respectively. This analytical procedure is properly validated, offering a reliable and simple way for monitoring APEOn in leather and textile.%建立了皮革及纺织品中烷基酚聚氧乙烯醚(APEOn)残留量的GC-MS测定方法.采用超声波辅助乙腈对样品中的APEOn进行萃取,萃取液中的APEOn经过三碘化铝裂解后,完全转化为等摩尔量的烷基酚(AP),然后采用气相色谱-质谱(GC-MS)对AP进行测试,最后根据AP的浓度计算样品APEOn的含量,以APEO9表示.结果表明:方法的回收率在91%~101%之间,相对标准偏差在5%~9%之间,壬基酚聚氧乙烯醚(NPEO9)的定量检测限为3.0mg/kg、辛基酚聚氧乙烯醚(OPEO9)为1.2mg/kg.方法的可靠性强、灵敏度高,为皮革及纺织品中APEOn残留量的有效监测提供了简便、可靠的检测技术.

  8. Stop-Catalyzed Baryogenesis Beyond the MSSM

    CERN Document Server

    Katz, Andrey; Ramsey-Musolf, Michael J; Winslow, Peter

    2015-01-01

    Non-minimal supersymmetric models that predict a tree-level Higgs mass above the Minimal Supersymmetric Standard Model (MSSM) bound are well motivated by naturalness considerations. Indirect constraints on the stop sector parameters of such models are significantly relaxed compared to the MSSM; in particular, both stops can have weak-scale masses. We revisit the stop-catalyzed electroweak baryogenesis (EWB) scenario in this context. We find that the LHC measurements of the Higgs boson production and decay rates already rule out the possibility of stop-catalyzed EWB. We also introduce a gauge-invariant analysis framework that may generalize to other scenarios in which interactions outside the gauge sector drive the electroweak phase transition.

  9. Palladium-Catalyzed Environmentally Benign Acylation.

    Science.gov (United States)

    Suchand, Basuli; Satyanarayana, Gedu

    2016-08-05

    Recent trends in research have gained an orientation toward developing efficient strategies using innocuous reagents. The earlier reported transition-metal-catalyzed carbonylations involved either toxic carbon monoxide (CO) gas as carbonylating agent or functional-group-assisted ortho sp(2) C-H activation (i.e., ortho acylation) or carbonylation by activation of the carbonyl group (i.e., via the formation of enamines). Contradicting these methods, here we describe an environmentally benign process, [Pd]-catalyzed direct carbonylation starting from simple and commercially available iodo arenes and aldehydes, for the synthesis of a wide variety of ketones. Moreover, this method comprises direct coupling of iodoarenes with aldehydes without activation of the carbonyl and also without directing group assistance. Significantly, the strategy was successfully applied to the synthesis n-butylphthalide and pitofenone.

  10. 典型乙氧基化装置中环氧乙烷安全操作分析%Analysis on Safe Operation of Using Epoxy Ethane in Typical Ethoxylation Plant

    Institute of Scientific and Technical Information of China (English)

    李宁

    2013-01-01

      介绍环氧乙烷操作风险以及导致环氧乙烷在典型乙氧基化反应器中没有有效的气相循环或没有气相循环操作条件下分解的主要原因。环氧乙烷在密闭乙氧基化反应器中达到爆炸极限时,是可以通过控制反应器中氮气浓度避免事故发生。%Main operational risks in using epoxy ethane were introduced as well as main reasons to not realize effective gas phase circulation of epoxy ethane and to cause epoxy ethane decomposition in typical ethoxylation plant. When ethylene oxide in a closed reactor reaches the explosion limit, to control nitrogen concentration in the reactor can avoid the accident.

  11. [Fragment reaction catalyzed by E. coli ribosomes].

    Science.gov (United States)

    Kotusov, V V; Kukhanova, M K; Sal'nikova, N E; Nikolaeva, L V; Kraevskiĭ, A A

    1977-01-01

    It has been shown that 50S subunits of E. coli MRE-600 ribosomes catalyze the reaction of N-(formyl)-methionyl ester of adenosine 5'-phosphate acting as peptide donor, with Phe-tRNA or CACCA-Phe serving as a peptide acceptor. The reaction is stimulated by cytidine 5'phosphate and inhibited by lincomycin, puromycin and chloramphenicol. The obtained results show that the structure of the donor site of peptidyltransferase is completely assembled on the 50S subunit and 30S subunit is not required for its formation.

  12. Chiral Diamine-catalyzed Asymmetric Aldol Reaction

    Institute of Scientific and Technical Information of China (English)

    LI Hui; XU Da-zhen; WU Lu-lu; WANG Yong-mei

    2012-01-01

    A highly efficient catalytic system composed of a simple and commercially available chiral primary diamine (1R,2R)-cyclohexane-1,2-diamine(6) and trifluoroacetic acid(TFA) was employed for asymmetric Aldol reaction in i-PrOH at room temperature.A loading of 10%(molar fraction) catalyst 6 with TFA as a cocatalyst could catalyze the Aldol reactions of various ketones or aldehydes with a series of aromatic aldehydes,furnishing Aldol products in moderate to high yields(up to >99%) with enantioselectivities of up to >99% and diastereoselectivities of up to 99:1.

  13. Ligand Intermediates in Metal-Catalyzed Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Gladysz, John A.

    1999-07-31

    The longest-running goal of this project has been the synthesis, isolation, and physical chemical characterization of homogeneous transition metal complexes containing ligand types believed to be intermediates in the metal-catalyzed conversion of CO/H{sub 2}, CO{sub 2}, CH{sub 4}, and similar raw materials to organic fuels, feedstocks, etc. In the current project period, complexes that contain unusual new types of C{sub x}(carbide) and C{sub x}O{sub y} (carbon oxide) ligands have been emphasized. A new program in homogeneous fluorous phase catalysis has been launched as described in the final report.

  14. Production of Fatty Methyl Ester Ethoxylates and Its Application in Leather Degreasing Process%脂肪酸甲酯乙氧基化物的生产及在毛皮脱脂中的应用

    Institute of Scientific and Technical Information of China (English)

    刘贺

    2012-01-01

    脂肪酸甲酯乙氧基化物(FMEE)是一种低泡沫的非离子型表面活性剂,在低温条件下(低于40℃)具有优异的脱脂性能,特别是分散力出众,在净洗过程中能够有效地防止油脂在转鼓内积聚,避免油脂的反沾污,适用于毛皮表面与内部的油脂和其它杂质的清洗.本文详细介绍了非离子净洗剂脂肪酸甲酯乙氧基化物FMEE的合成以及在清洗动物油脂过程中的应用和优点,探讨了FMEE在毛皮实际脱脂生产工艺中的参数以及废水处理.%Fatty acid methyl ester ethoxylates ( FMEE ) is a low foam non-ionic surfactant. FMEE has the excellent degreasing capacity, with superior dispersibility under the condition of low temperature (<40℃). FMEE can prevent fat from storing up in the rotary drum in the washing process effectively and avoid reverse staining of fat. Therefore, FMEE is suitable for degreasing on the surface and inside the leather, as well as impurity cleaning. This paper introduced the synthesis of nonionic detergent -fatty acid methyl ester ethoxylates (FMEE) as well as its application and advantage in degreasing process. This paper also discussed the process parameters of FMEE in leather degreasing process including wastewater treatment.

  15. Biginelli Reaction Catalyzed by Copper Nanoparticles

    Science.gov (United States)

    Dewan, Manika; Kumar, Ajeet; Saxena, Amit; De, Arnab; Mozumdar, Subho

    2012-01-01

    We recently reported a novel synthesis of copper nanoparticles from copper sulphate utilizing the charge-compensatory effect of ionic liquid [bmim]BF4 and ethylene glycol. The nanoparticles were characterized and found to be stable for one year. Here we hypothesize that the stabilized nanoparticles should be able to catalyze one-pot multicomponent organic reactions. We show that the nanoparticles catalyzed Biginelli reaction at room temperature to give the product 3,4-dihydopyrimidinone (>90% yield in ∼15 minutes) from aldehydes, β-diketoester (ethylacetoacetate) and urea (or thiourea). ). Remarkably, such high yields and rapid kinetics was found to be independent of the electronic density on the reactant aryl-aldehyde. This was probably because even the surface-active particles reacted faster in the presence of ionic liquid as compared to conventional methods. The heterocyclic dihydropyrimidinones (DHPMs) and their derivatives are widely used in natural and synthetic organic chemistry due to their wide spectrum of biological and therapeutic properties (resulting from their antibacterial, antiviral, antitumor and anti-inflammatory activities. Our method has an easy work-up procedure and the nanoparticles could be recycled with minimal loss of efficiency. PMID:22912792

  16. Palladium-Catalyzed Arylation of Fluoroalkylamines

    Science.gov (United States)

    Brusoe, Andrew T.; Hartwig, John F.

    2015-01-01

    We report the synthesis of fluorinated anilines by palladium-catalyzed coupling of fluoroalkylamines with aryl bromides and aryl chlorides. The products of these reactions are valuable because anilines typically require the presence of an electron-withdrawing substituent on nitrogen to suppress aerobic or metabolic oxidation, and the fluoroalkyl groups have steric properties and polarity distinct from those of more common electron-withdrawing amide and sulfonamide units. The fluoroalkylaniline products are unstable under typical conditions for C–N coupling reactions (heat and strong base). However, the reactions conducted with the weaker base KOPh, which has rarely been used in cross-coupling to form C–N bonds, occurred in high yield in the presence of a catalyst derived from commercially available AdBippyPhos and [Pd(allyl)Cl]2. Under these conditions, the reactions occur with low catalyst loadings (<0.50 mol % for most substrates) and tolerate the presence of various functional groups that react with the strong bases that are typically used in Pd-catalyzed C–N cross-coupling reactions of aryl halides. The resting state of the catalyst is the phenoxide complex, (BippyPhosPd(Ar)OPh); due to the electron-withdrawing property of the fluoroalkyl substituent, the turnover-limiting step of the reaction is reductive elimination to form the C–N bond. PMID:26065341

  17. Biginelli reaction catalyzed by copper nanoparticles.

    Directory of Open Access Journals (Sweden)

    Manika Dewan

    Full Text Available We recently reported a novel synthesis of copper nanoparticles from copper sulphate utilizing the charge-compensatory effect of ionic liquid [bmim]BF(4 and ethylene glycol. The nanoparticles were characterized and found to be stable for one year. Here we hypothesize that the stabilized nanoparticles should be able to catalyze one-pot multicomponent organic reactions. We show that the nanoparticles catalyzed Biginelli reaction at room temperature to give the product 3,4-dihydopyrimidinone (>90% yield in ~15 minutes from aldehydes, β-diketoester (ethylacetoacetate and urea (or thiourea. . Remarkably, such high yields and rapid kinetics was found to be independent of the electronic density on the reactant aryl-aldehyde. This was probably because even the surface-active particles reacted faster in the presence of ionic liquid as compared to conventional methods. The heterocyclic dihydropyrimidinones (DHPMs and their derivatives are widely used in natural and synthetic organic chemistry due to their wide spectrum of biological and therapeutic properties (resulting from their antibacterial, antiviral, antitumor and anti-inflammatory activities. Our method has an easy work-up procedure and the nanoparticles could be recycled with minimal loss of efficiency.

  18. Manganese Catalyzed C-H Halogenation.

    Science.gov (United States)

    Liu, Wei; Groves, John T

    2015-06-16

    The remarkable aliphatic C-H hydroxylations catalyzed by the heme-containing enzyme, cytochrome P450, have attracted sustained attention for more than four decades. The effectiveness of P450 enzymes as highly selective biocatalysts for a wide range of oxygenation reactions of complex substrates has driven chemists to develop synthetic metalloporphyrin model compounds that mimic P450 reactivity. Among various known metalloporphyrins, manganese derivatives have received considerable attention since they have been shown to be versatile and powerful mediators for alkane hydroxylation and olefin epoxidation. Mechanistic studies have shown that the key intermediates of the manganese porphyrin-catalyzed oxygenation reactions include oxo- and dioxomanganese(V) species that transfer an oxygen atom to the substrate through a hydrogen abstraction/oxygen recombination pathway known as the oxygen rebound mechanism. Application of manganese porphyrins has been largely restricted to catalysis of oxygenation reactions until recently, however, due to ultrafast oxygen transfer rates. In this Account, we discuss recently developed carbon-halogen bond formation, including fluorination reactions catalyzed by manganese porphyrins and related salen species. We found that biphasic sodium hypochlorite/manganese porphyrin systems can efficiently and selectively convert even unactivated aliphatic C-H bonds to C-Cl bonds. An understanding of this novel reactivity derived from results obtained for the oxidation of the mechanistically diagnostic substrate and radical clock, norcarane. Significantly, the oxygen rebound rate in Mn-mediated hydroxylation is highly correlated with the nature of the trans-axial ligands bound to the manganese center (L-Mn(V)═O). Based on the ability of fluoride ion to decelerate the oxygen rebound step, we envisaged that a relatively long-lived substrate radical could be trapped by a Mn-F fluorine source, effecting carbon-fluorine bond formation. Indeed, this idea

  19. Oxazolidinone Synthesis through Halohydrin Dehalogenase-Catalyzed Dynamic Kinetic Resolution

    NARCIS (Netherlands)

    Mikleusevic, Ana; Hamersak, Zdenko; Salopek-Sondi, Branka; Tang, Lixia; Janssen, Dick B.; Elenkov, Maja Majeric

    2015-01-01

    An efficient dynamic kinetic resolution protocol using a single enzyme is described. Both the kinetic resolution and substrate racemization are catalyzed by halohydrin dehalogenase from Agrobacterium radiobacter AD1 (HheC). The HheC-catalyzed reaction of epibromohydrin and

  20. Synthetic applications of gold-catalyzed ring expansions

    Directory of Open Access Journals (Sweden)

    Cristina Nevado

    2011-06-01

    Full Text Available The development of new methodologies catalyzed by late transition metals involving cycloisomerizations of strained rings can open new venues for the synthesis of structurally complex molecules with interesting biological activities. Herein we summarize, from both a synthetic as well as a mechanistic point of view, the most recent developments in gold-catalyzed ring expansions.

  1. Lipase-catalyzed production of lysophospholipids

    Directory of Open Access Journals (Sweden)

    Mnasri Taha

    2017-07-01

    Full Text Available Lysophospholipids, such as lysophosphatidic acid or lysophosphatidylcholine, are important bioactive lipids, involved in various normal and pathological cellular processes. They also have industrial and pharmaceutical uses such as emulsifiers or components of drug delivery systems. Lipases, which natural substrates are long chain triacylglycerols, are important biocatalysts for organic synthesis mainly due to their broad substrate specificity and their ability to display high catalytic activity in organic media. This paper describes the various lipase-catalyzed reactions implemented for the production of lysophospholipids. They include hydrolysis or alcoholysis of phospholipids and acylation of the glycerophosphoryl moiety. Special emphasis is made on our work dealing with the production of lysophospholipids rich in dososahexaenoic acid, an important dietary polyunsaturated fatty acid via the hydrolysis of phospholipids extracted from the microalga Isochrysis galbana.

  2. Heterogeneously Catalyzed Oxidation Reactions Using Molecular Oxygen

    DEFF Research Database (Denmark)

    Beier, Matthias Josef

    Heterogeneously catalyzed selective oxidation reactions have attracted a lot of attention in recent time. The first part of the present thesis provides an overview over heterogeneous copper and silver catalysts for selective oxidations in the liquid phase and compared the performance and catalytic...... that both copper and silver can function as complementary catalyst materials to gold showing different catalytic properties and being more suitable for hydrocarbon oxidation reactions. Potential opportunities for future research were outlined. In an experimental study, the potential of silver as a catalyst...... revealed that all catalysts were more active in combination with ceria nanoparticles and that under the tested reaction conditions silver was equally or even more efficient than the gold catalysts. Calcination at 900 °C of silver on silica prepared by impregnation afforded a catalyst which was used...

  3. Rhodium-Catalyzed Alkene Difunctionalization with Nitrenes.

    Science.gov (United States)

    Ciesielski, Jennifer; Dequirez, Geoffroy; Retailleau, Pascal; Gandon, Vincent; Dauban, Philippe

    2016-06-27

    The Rh(II) -catalyzed oxyamination and diamination of alkenes generate 1,2-amino alcohols and 1,2-diamines, respectively, in good to excellent yields and with complete regiocontrol. In the case of diamination, the intramolecular reaction provides an efficient method for the preparation of pyrrolidines, and the intermolecular reaction produces vicinal amines with orthogonal protecting groups. These alkene difunctionalizations proceed by aziridination followed by nucleophilic ring opening induced by an Rh-bound nitrene generated in situ, details of which were uncovered by both experimental and theoretical studies. In particular, DFT calculations show that the nitrogen atom of the putative [Rh]2 =NR metallanitrene intermediate is electrophilic and support an aziridine activation pathway by N⋅⋅⋅N=[Rh]2 bond formation, in addition to the N⋅⋅⋅[Rh]2 =NR coordination mode. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Enzyme-catalyzed degradation of carbon nanomaterials

    Science.gov (United States)

    Kotchey, Gregg P.

    Carbon nanotubes and graphene, the nanoscale sp 2 allotropes of carbon, have garnered widespread attention as a result of their remarkable electrical, mechanical, and optical properties and the promise of new technologies that harness these properties. Consequently, these carbon nanomaterials (CNMs) have been employed for diverse applications such as electronics, sensors, composite materials, energy conversion devices, and nanomedicine. The manufacture and eventual disposal of these products may result in the release of CNMs into the environment and subsequent exposure to humans, animals, and vegetation. Given the possible pro-inflammatory and toxic effects of CNMs, much attention has been focused on the distribution, toxicity, and persistence of CNMs both in living systems and the environment. This dissertation will guide the reader though recent studies aimed at elucidating fundamental insight into the persistence of CNMs such as carbon nanotubes (CNTs) and graphene derivatives (i.e., graphene oxide and reduced graphene oxide). In particular, in-testtube oxidation/degradation of CNMs catalyzed by peroxidase enzymes will be examined, and the current understanding of the mechanisms underlying these processes will be discussed. Finally, an outlook of the current field including in vitro and in vivo biodegradation experiments, which have benefits in terms of human health and environmental safety, and future directions that could have implications for nanomedical applications such as imaging and drug delivery will be presented. Armed with an understanding of how and why CNMs undergo enzyme-catalyzed oxidation/biodegradation, researchers can tailor the structure of CNMs to either promote or inhibit these processes. For example, in nanomedical applications such as drug delivery, the incorporation of carboxylate functional groups could facilitate biodegradation of the nanomaterial after delivery of the cargo. Also, the incorporation of CNMs with defect sites in consumer

  5. Synthesis of Lactonic Crown Ethers by Ethoxylation of γ-Butyrolactone%γ-丁内酯乙氧基化合成内酯冠醚

    Institute of Scientific and Technical Information of China (English)

    胡学一; 方云; 赵权

    2012-01-01

    Lactonic crown ethers were synthesized by a novel insertion reaction oi ethylene oxides into γ-butyrolac:tone(GBL) catalyzed by Al-Mg composite oxide, and the molecular structures of the target products were confirmed by FTIR and ES1-MS. The process was optimized with respect to Al/Mg molar ratio of catalysts, reaction temperature and pressure. The conversion of GBL was 75.2% when the insertion reaction was catalyzed by 1% of LE -4 catalyst based on the target products and run in 5 times molar ratio of EO to GBL at 160℃ under 0.65 MPa.%以Al-Mg基复合氧化物为催化剂,尝试采用环氧乙烷(EO)分子插入γ-丁内酯(GBL)的新反应合成内酯冠醚,用FTIR和ESI-MS对目标产物结构进行了确证.实验结果表明,LE-4催化剂的催化效果最佳;对反应温度和压力的优化实验进一步表明,当使用质量分数1%的LE-4催化剂,EO与GBL的摩尔比为5时,优化反应温度和体系压力分别为160℃和0.65 MPa,GBL转化率达到75.2%.

  6. Oxygenase-catalyzed ribosome hydroxylation occurs in prokaryotes and humans.

    Science.gov (United States)

    Ge, Wei; Wolf, Alexander; Feng, Tianshu; Ho, Chia-Hua; Sekirnik, Rok; Zayer, Adam; Granatino, Nicolas; Cockman, Matthew E; Loenarz, Christoph; Loik, Nikita D; Hardy, Adam P; Claridge, Timothy D W; Hamed, Refaat B; Chowdhury, Rasheduzzaman; Gong, Lingzhi; Robinson, Carol V; Trudgian, David C; Jiang, Miao; Mackeen, Mukram M; Mccullagh, James S; Gordiyenko, Yuliya; Thalhammer, Armin; Yamamoto, Atsushi; Yang, Ming; Liu-Yi, Phebee; Zhang, Zhihong; Schmidt-Zachmann, Marion; Kessler, Benedikt M; Ratcliffe, Peter J; Preston, Gail M; Coleman, Mathew L; Schofield, Christopher J

    2012-12-01

    The finding that oxygenase-catalyzed protein hydroxylation regulates animal transcription raises questions as to whether the translation machinery and prokaryotic proteins are analogously modified. Escherichia coli ycfD is a growth-regulating 2-oxoglutarate oxygenase catalyzing arginyl hydroxylation of the ribosomal protein Rpl16. Human ycfD homologs, Myc-induced nuclear antigen (MINA53) and NO66, are also linked to growth and catalyze histidyl hydroxylation of Rpl27a and Rpl8, respectively. This work reveals new therapeutic possibilities via oxygenase inhibition and by targeting modified over unmodified ribosomes.

  7. Syntheses of Styrene-acrylic Emulsion Using Alkylalcohol Gemini Surfactants to Replace Alkylphenolic Ethoxylates%用烷基醇Gemini表面活性剂替代烷基酚聚氧乙烯醚合成苯丙乳液

    Institute of Scientific and Technical Information of China (English)

    郑清皇; 张超; 陈燕红; 吴宗华

    2012-01-01

    The syntheses of styrene-acrylic emulsion was carried out, using the following three emulsifiers: the sodium polyethylene-glycol octyl alcohol sufisuccinates (RCS-8), the sodium polyethylene-glycol lauryl alcohol sufisuccinates (RCS-12) and the sodium succinate nonylphenol ethoxylate (RCD-NP) respectively. Their surface tension, mechanical stability, partical size and particle size distributions were determined and compared to others. The results showed that the syntheses of styrene-acrylic emulsion could be used the alkyl-alcohol Gemini surfactants to replace the alkyl-phenol ethoxylates, the structures of emulsifiers had a big effect on the syntheses. The main physicochemical properties of the styrene-acrylic emulsion synthesized by the emulsifiers of RCS-8 and RCD-NP had no obvious difference, but the gel-rate, mechanical stability, and particle size distributions were better than the latter. When the temperature of polymerization was 80 °C, the amount of initiator was 1 % of monomer contents, the partical size of styrene-acrylic emulsion which was synthesized by RCS-8 was the smallest, the partical size distribution was the narrowest.%分别用琥珀酸聚乙二醇辛醇双酯磺酸钠(RCS-8),琥珀酸聚乙二醇十二正烷醇双酯磺酸钠(RCS-12)和琥珀酸壬基酚聚氧乙烯(10)醚酯磺酸钠(RCD-NP)为乳化剂合成了苯丙乳液,并进行了乳液表面张力、机械稳定性、粒径和粒径分布等的测试和比较.结果表明,烷基醇Gemini表面活性剂可以取代烷基酚聚氧乙烯醚用于苯丙乳液合成,其结构对合成乳液的性能影响大.采用RCS-8与RCD-NP为乳化剂合成的苯丙乳液其主要理化性能无明显差异,而其凝胶率、机械稳定性、粒径分布等方面优于后者.聚合温度为80℃,引发剂用量为单体质量的1%时,用RCS-8合成的苯丙乳液的粒径最小,粒径分布范围最窄.

  8. Study on adsorption kinetics of octylphenol ethoxylates onto silk fiber%蚕丝纤维吸附辛基酚聚氧乙烯醚的动力学研究

    Institute of Scientific and Technical Information of China (English)

    李丹; 董锁拽; 翁伟明; 周文龙

    2011-01-01

    为实现蚕丝产品中烷基酚聚氧乙烯醚( APEO)的高效监控检测,研究蚕丝纤维对辛基酚聚氧乙烯醚(OPEO)的吸附特性.结果表明,OPEO在蚕丝纤维上的吸附符合Langmuir模型,吸附动力学符合拟二级动力学模型,并且初始浓度越大,平衡速率常数越小,到达平衡的时间越长.OPEO溶液的温度越高,平衡速率常数越大.毛孔内扩散是控制OPEO在蚕丝纤维上吸附的一个因素,但不是唯一的因素.OPEO在蚕丝纤维上的吸附活化能为25.69 kJ/mol,活化能远小于化学吸附所需的83.72 kJ/mol,说明OPEO在蚕丝纤维上的吸附是以物理吸附为主.%Silk fiber's adsorption of octylphenol ethoxylates (OPEO) was studied in order to realize high efficiency monitoring and detection of alkylphenol ethoxylates ( APnEO) in silk products. The results showed that silk fiber's adsorption of OPEO fitted Langmuir model, and the adsorption process could be well described by the pseudo-second-order kinetic model. And higher the initial OPEO concentration, smaller the balancing rate constant was, and longer the balancing time was; higher the temperature of OPEO solution, greater the balancing rate constant was. The diffusion into the microspore is a main factor for controlling the silk fiber adsorption of OPEO, but it is not the only factor. The adsorption activation energy is 25.69 Kj/mol in silk fiber of OPEO, which is far lower than that required by chemical adsorption, that is, 83.72 kj/mol. It indicates that physical adsorption dominates the silk fiber absorption of OPEA.

  9. Mechanisms of bacterially catalyzed reductive dehalogenation

    Energy Technology Data Exchange (ETDEWEB)

    Picardal, F.W.

    1992-12-31

    Nine bacteria were tested for the ability to dehalogenate tetrachloromethane (CT), tetrachloroethene (PCE), and 1, 1, 1-trichloroethane (TCA) under anaerobic conditions. Three bacteria were able to reductively dehalogenate CT. Dehalogenation ability was not readily linked to a common metabolism or changes in culture redox potential. None of the bacteria tested were able to dehalogenate PCE or TCA. One of the bacteria capable of dehalogenating CT, Shewanella putrefaciens, was chosen as a model organism to study mechanisms of bacterially catalyzed reductive dehalogenation. The effect of a variety of alternate electron acceptors on CT dehalogenation ability by S. putrefaciens was determined. oxygen and nitrogen oxides were inhibitory but Fe (III), trimethylamine oxide, and fumarate were not. A model of the electron transport chain of S. putrefaciens was developed to explain inhibition patterns. A period of microaerobic growth prior to CT exposure increased the ability of S. putrefaciens to dehalogenate CT. A microaerobic growth period also increased cytochrome concentrations. A relationship between cytochrome content and dehalogenation ability was developed from studies in which cytochrome concentrations in S. putrefaciens were manipulated by changing growth conditions. Stoichiometry studies using {sup 14}C-CT suggested that CT was first reduced to form a trichloromethyl radical. Reduction of the radical to produce chloroform and reaction of the radical with cellular biochemicals explained observed product distributions. Carbon dioxide or other fully dehalogenated products were not found.

  10. Iridium-Catalyzed Hydrogen Transfer Reactions

    Science.gov (United States)

    Saidi, Ourida; Williams, Jonathan M. J.

    This chapter describes the application of iridium complexes to catalytic hydrogen transfer reactions. Transfer hydrogenation reactions provide an alternative to direct hydrogenation for the reduction of a range of substrates. A hydrogen donor, typically an alcohol or formic acid, can be used as the source of hydrogen for the reduction of carbonyl compounds, imines, and alkenes. Heteroaromatic compounds and even carbon dioxide have also been reduced by transfer hydrogenation reactions. In the reverse process, the oxidation of alcohols to carbonyl compounds can be achieved by iridium-catalyzed hydrogen transfer reactions, where a ketone or alkene is used as a suitable hydrogen acceptor. The reversible nature of many hydrogen transfer processes has been exploited for the racemization of alcohols, where temporary removal of hydrogen generates an achiral ketone intermediate. In addition, there is a growing body of work where temporary removal of hydrogen provides an opportunity for using alcohols as alkylating agents. In this chemistry, an iridium catalyst "borrows" hydrogen from an alcohol to give an aldehyde or ketone intermediate, which can be transformed into either an imine or alkene under the reaction conditions. Return of the hydrogen from the catalyst provides methodology for the formation of amines or C-C bonds where the only by-product is typically water.

  11. Determination of Alkylphenol Ethoxylates in Textiles by GelFiltration Chromatography-Tandem Mass Spectrometry%凝胶过滤色谱-串联质谱法测定纺织品中的烷基酚聚氧乙烯醚

    Institute of Scientific and Technical Information of China (English)

    马强; 王超; 白桦; 刘茜; 王烨; 席海为

    2012-01-01

    A comprehensive analytical method based on gel filtration chromatography-tandem quadrupole mass spectrometry has been developed for the determination of alkylphenol ethoxylates in textiles. The textile samples were extracted with ethanol by accelerated solvent extraction method. The extract was cleaned by a Sep-Pak Carbon/NH2 solid phase extraction cartridge. Qualitative and quantitative analyses were carried out for alkylphenol ethoxylates under the multiple reaction monitoring (MRM) mode after the chromatographic separation on Shodex MSpak GF-310 2D column (150×2. 0 mm). The limits of quantitation (LOQs) for nonylphenol ethoxylates and octylphenol ethoxylates were 0. 2 mg/kg. At the spiked levels of 0. 2~5 mg/kg,the mean recoveries for nonylphenol ethoxylates were 84. 2%~93. 5% with the relative standard deviations (RSDs) of 3. 9%~7. 5%,and the mean recoveries for octylphenol ethoxylates were 85. 5%~96. 1% with the relative standard deviations (RSDs) of 3. 4%~8. 1%. The method is suitable for the determination of alkylphenol ethoxylates in textiles.%建立了纺织品中烷基酚聚氧乙烯醚的凝胶过滤色谱-串联质谱(GFC-MS/MS)分析方法.纺织品样品采用加速溶剂萃取法,以无水乙醇为提取溶剂进行提取,提取液经Sep-Pak Carbon/NH2石墨化碳黑/氨基复合型固相萃取柱净化.烷基酚聚氧乙烯醚经Shodex MSpak GF-310 2D色谱柱(150×2.0 mm)分离后,在多反应监测(MRM)模式下进行串联质谱定性及定量分析.方法对壬基酚聚氧乙烯醚(NPnEO)和辛基酚聚氧乙烯醚(OPnEO)的定量眼均为0.2mg/kg,在0.2~5 mg/kg的3个添加水平范围内,NPnEO的平均回收率为84.2%~93.5%,相对标准偏差(RSD)为3.9%~7.5%;OPnEO的平均回收率为85.5%~96.1%,RSD为3.4%~8.1%.该方法能够满足纺织品中烷基酚聚氧乙烯醚的检测要求.

  12. Cyclopalladated Ferrocenylimine Catalyzed Chlorination of 2-Arylbenzoxazoles%Cyclopalladated Ferrocenylimine Catalyzed Chlorination of 2-Arylbenzoxazoles

    Institute of Scientific and Technical Information of China (English)

    冷瑜婷; 杨帆; 吴养洁; 李克

    2011-01-01

    An efficient and facile protocol for palladacycle-catalyzed chlorination of 2-arylbenzoxazoles was developed. The results represent the first examples involving the palladacycle as the catalyst for such chlorination. This chlori- nation was not a ligand-directed ortho-C--H activation, but an electrophilic substitution process at the para-position of the nitrogen atom in the benzo ring of benzoxazole moiety, the regiochemistry of which had been confirmed by HMBC spectral analysis. The catalytic system could tolerate various halogen atoms, such as F, Cl and Br, affording the corresponding products in moderate to excellent yields.

  13. Platinum-Catalyzed Selective Tin-Carbon Bond Formation

    NARCIS (Netherlands)

    Thoonen, Sander Hendrikus Lambertus

    2003-01-01

    In conclusion, two improved methods for the selective synthesis of monoorganotin trihalides were developed. The platinum-catalyzed Kocheshkov redistribution reaction of dialkyltin dichlorides with tin tetrachloride is the most interesting. Contrary to the other two methods described (the direct

  14. Functioned Calix[4]arenes as Artificial Enzymes Catalyze Aldol Condensation

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Aldolase models derived from calix[4]arene were designed and synthesized. The aldol condensation of p-nitrobenzaldehyde with acetone was catalyzed by the synthetic enzymes proceeded under mild conditions to offer chiefly aldol-type product in good yield.

  15. Diastereoselective Pt catalyzed cycloisomerization of polyenes to polycycles.

    Science.gov (United States)

    Geier, Michael J; Gagné, Michel R

    2014-02-26

    Application of a tridentate NHC containing pincer ligand to Pt catalyzed cascade cyclization reactions has allowed for the catalytic, diastereoselective cycloisomerization of biogenic alkene terminated substrates to the their polycyclic counterparts.

  16. Lipase catalyzed synthesis of epoxy-fatty acids

    Institute of Scientific and Technical Information of China (English)

    CHEN, Qian; LI, Zu-Yi

    2000-01-01

    Lipase catalyzed synthesis of epoxy-fatty acidas from unsaturated carboxylic acids was investigated.Under mild conditions unsaturated arboxylic acids were convcveed to peroxide,then the unsaturated peroxycarboxylic acids epoxidised the C=C bond of themselves

  17. A New Palladium-Catalyzed Phenyl-Alkene Bond Formation

    Directory of Open Access Journals (Sweden)

    René Roy

    2002-05-01

    Full Text Available A new method of palladium-catalyzed phenyl-alkene bond formation is reported. This reaction involves transfer of all three phenyl groups from triphenylantimony onto alkenes containing allylic protons.

  18. Homocoupling of Aryl Bromides Catalyzed by Nickel Chloride in Pyridine

    Institute of Scientific and Technical Information of China (English)

    TAO, Xiao-Chun; ZHOU, Wei; ZHANG, Yue-Ping; DAI, Chun-ya; SHEN, Dong; HUANG, Mei

    2006-01-01

    Pyridine was used as a solvent for homocoupling of aryl bromides catalyzed by nickel chloride/triarylphosphine in the presence of zinc and recycled easily. Triphenylphosphine was the best ligand for nickel in this coupling reaction.

  19. Gold-Catalyzed Regioselective Dimerization of Aliphatic Terminal Alkynes.

    Science.gov (United States)

    Sun, Sheng; Kroll, Julien; Luo, Yingdong; Zhang, Liming

    2012-01-01

    A gold-catalyzed regioselective homodimerization of aliphatic terminal alkynes is described. Bulky and less Lewis acidic tBuXPhosAuNTf(2) is the preferred catalyst, and the additive, anhydrous NaOAc, substantially facilitates the reaction.

  20. LIPASE-CATALYZED TRANSESTERIFICATION OF PALM KERNEL OIL WITH DIALKYLCARBONATES

    OpenAIRE

    Tjahjono Herawan; M. Rüsch Gen. Klaas

    2014-01-01

    Lipase-catalyzed transesterifications-especially in a solvent-free medium-are important for industrial applications because such systems would have an enormous advantage by avoiding the problem of separation, toxicity and flammability of organic solvents. However, the organic solvent-free alcoholysis, especially methanolysis, does not give high conversions. The same problem also occurs when ethyl or methyl acetate are used as acyl acceptors. The main problems of lipase-catalyzed organic solve...

  1. Copper-Catalyzed Aerobic C–H Trifluoromethylation of Phenanthrolines

    Science.gov (United States)

    Zhu, Cheng-Liang; Zhang, Yong-Qiang; Yuan, Yong-An

    2016-01-01

    Direct C–H trifluoromethylation of heterocycles is a valuable transformation. In particular, nonprecious metal-catalyzed C–H trifluoromethylation processes, which do not proceed through CF3 radical species, have been less developed. In this cluster report, a new copper-catalyzed aerobic C–H trifluoromethylation of phenanthrolines is described. This transformation affords trifluoromethylated phenanthrolines that have not been synthesized and preliminary mechanistic studies suggest that the CF3 group transfer may occur through cooperative activation. PMID:26855477

  2. Development and industrial application of catalyzer for low-temperature hydrogenation hydrolysis of Claus tail gas

    OpenAIRE

    Honggang Chang; Ronghai Zhu; Zongshe Liu; Jinlong He; Chongrong Wen; Sujuan Zhang; Yang Li

    2015-01-01

    With the implementation of more strict national environmental protection laws, energy conservation, emission reduction and clean production will present higher requirements for sulfur recovery tail gas processing techniques and catalyzers. As for Claus tail gas, conventional hydrogenation catalyzers are gradually being replaced by low-temperature hydrogenation catalyzers. This paper concentrates on the development of technologies for low-temperature hydrogenation hydrolysis catalyzers, prepar...

  3. Photodegradation Behavior and Estrogenic Effect of Alkylphenol Ethoxylates in UV/H2O2Treatment Processes%烷基酚聚氧乙烯醚的光降解行为和雌激素效应

    Institute of Scientific and Technical Information of China (English)

    刘光明; 魏芳; 余华锋

    2011-01-01

    A representative alkylphenol ethoxylates Triton X-100 (TX) was photodegradated in water by UV/H2O2 treatment processes. The photodegradation kinetics of TX and multiple influencing factors were investigated. With nitrobenzene as molecular probe in competitive kinetic experiment, the steady-state concentration of ·OH was measured. The estrogenic effect of TX through the photodegradation process was determined by recombinant gene yeast. The result shows estrogenic effect has no significant change through photodegradation process.%利用UV/H2O2工艺对典型的烷基酚聚氧乙烯醚类物质Triton X-100(TX)进行降解,考察了不同反应条件对降解效果的影响,并且使用分子探针法测定了光解体系中羟基自由基的稳态浓度.以人类雌激素受体重组基因酵母测定其光降解过程中的雌激素效应变化,结果表明雌激素效应并未随着光解过程有较大的变化.

  4. Conservation Kickstart- Catalyzing Conservation Initiatives Worldwide

    Science.gov (United States)

    Treinish, G.

    2014-12-01

    Adventurers and Scientists for Conservation (ASC) is a nonprofit organization that collects environmental data to catalyze conservation initiatives worldwide. Adventure athletes have the skills and motivation to reach the most remote corners of the world. ASC utilizes those skills to provide the scientific community with data while providing the outdoor community with purpose beyond the personal high of reaching a summit or rowing across an ocean. We carefully select projects, choosing partnerships that will maximize the impact of ASC volunteers. Each project must have a clear path to a tangible conservation outcome and demonstrate a clear need for our brand of volunteers. We partner with government agencies, universities, and independant reseachers to kickstart data collection efforts around the world. Last year, through a partnership with the Olympic National Forest, 20 volunteers from the Seattle area set up and monitored camera traps in an effort to survey for costal Pacific marten. Our work led to the species' listing as "critically imperiled" with NatureServe. A partnership with the inaugural Great Pacific Race, engaging trans-Pacific rowing teams, searched for microplastics in the Pacific Ocean as part of our ongoing microplastics campaign. In a multi-year partnership with the American Prairie Reserve (APR), ASC volunteer crews live and work on the Reserve collecting wildlife data year round. The data we obtain directly informs the Reserve's wildlife management decisions. On this project, our crews have safely and effectively navigated temperature extremes from -30 degrees to 100+ degrees while traveling in a remote location. We are currently scouting projects in the Okavango Delta of Botswana and the rainforest of Suriname where we will be able to cover large amounts of area in a short periord of time. ASC is at the crossroads of the adventure and coservation science communities. Our approach of answering specific questions by using highly skilled and

  5. The Structural Basis of Ribozyme-Catalyzed RNA Assembly

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, M.P.; Scott, W.G.; /UC, Santa Cruz

    2007-07-12

    Life originated, according to the RNA World hypothesis, from self-replicating ribozymes that catalyzed ligation of RNA fragments. We have solved the 2.6 angstrom crystal structure of a ligase ribozyme that catalyzes regiospecific formation of a 5' to 3' phosphodiester bond between the 5'-triphosphate and the 3'-hydroxyl termini of two RNA fragments. Invariant residues form tertiary contacts that stabilize a flexible stem of the ribozyme at the ligation site, where an essential magnesium ion coordinates three phosphates. The structure of the active site permits us to suggest how transition-state stabilization and a general base may catalyze the ligation reaction required for prebiotic RNA assembly.

  6. Palladium-Catalyzed Modification of Unprotected Nucleosides, Nucleotides, and Oligonucleotides

    Directory of Open Access Journals (Sweden)

    Kevin H. Shaughnessy

    2015-05-01

    Full Text Available Synthetic modification of nucleoside structures provides access to molecules of interest as pharmaceuticals, biochemical probes, and models to study diseases. Covalent modification of the purine and pyrimidine bases is an important strategy for the synthesis of these adducts. Palladium-catalyzed cross-coupling is a powerful method to attach groups to the base heterocycles through the formation of new carbon-carbon and carbon-heteroatom bonds. In this review, approaches to palladium-catalyzed modification of unprotected nucleosides, nucleotides, and oligonucleotides are reviewed. Polar reaction media, such as water or polar aprotic solvents, allow reactions to be performed directly on the hydrophilic nucleosides and nucleotides without the need to use protecting groups. Homogeneous aqueous-phase coupling reactions catalyzed by palladium complexes of water-soluble ligands provide a general approach to the synthesis of modified nucleosides, nucleotides, and oligonucleotides.

  7. Highly efficient palladium-catalyzed hydrostannation of ethyl ethynyl ether.

    Science.gov (United States)

    Andrews, Ian P; Kwon, Ohyun

    2008-12-08

    The palladium-catalyzed hydrostannation of acetylenes is widely exploited in organic synthesis as a means of forming vinyl stannanes for use in palladium-catalyzed cross-coupling reactions. Application of this methodology to ethyl ethynyl ether results in an enol ether that is challenging to isolate from the crude reaction mixture because of incompatibility with typical silica gel chromatography. Reported here is a highly efficient procedure for the palladium-catalyzed hydrostannation of ethyl ethynyl ether using 0.1% palladium(0) catalyst and 1.0 equiv of tributyltin hydride. The product obtained is a mixture of regioisomers that can be carried forward with exclusive reaction of the beta-isomer. This method is highly reproducible; relative to previously reported procedures, it is more economical and involves a more facile purification procedure.

  8. Microbial-Catalyzed Biotransformation of Multifunctional Triterpenoids Derived from Phytonutrients

    Directory of Open Access Journals (Sweden)

    Syed Adnan Ali Shah

    2014-07-01

    Full Text Available Microbial-catalyzed biotransformations have considerable potential for the generation of an enormous variety of structurally diversified organic compounds, especially natural products with complex structures like triterpenoids. They offer efficient and economical ways to produce semi-synthetic analogues and novel lead molecules. Microorganisms such as bacteria and fungi could catalyze chemo-, regio- and stereospecific hydroxylations of diverse triterpenoid substrates that are extremely difficult to produce by chemical routes. During recent years, considerable research has been performed on the microbial transformation of bioactive triterpenoids, in order to obtain biologically active molecules with diverse structures features. This article reviews the microbial modifications of tetranortriterpenoids, tetracyclic triterpenoids and pentacyclic triterpenoids.

  9. New Palladium-Catalyzed Approaches to Heterocycles and Carbocycles

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Qinhua [Iowa State Univ., Ames, IA (United States)

    2004-12-19

    The tert-butylimines of o-(1-alkynyl)benzaldehydes and analogous pyridinecarbaldehydes have been cyclized under very mild reaction conditions in the presence of I2, ICl, PhSeCl, PhSCl and p-O2NC6H4SCl to give the corresponding halogen-, selenium- and sulfur-containing disubstituted isoquinolines and naphthyridines, respectively. Monosubstituted isoquinolines and naphthyridines have been synthesized by the metal-catalyzed ring closure of these same iminoalkynes. This methodology accommodates a variety of iminoalkynes and affords the anticipated heterocycles in moderate to excellent yields. The Pd(II)-catalyzed cyclization of 2-(1-alkynyl)arylaldimines in the presence of various alkenes provides an efficient way to synthesize a variety of 4-(1-alkenyl)-3-arylisoquinolines in moderate to excellent yields. The introduction of an ortho-methoxy group on the arylaldimine promotes the Pd-catalyzed cyclization and stabilizes the resulting Pd(II) intermediate, improving the yields of the isoquinoline products. Highly substituted naphthalenes have been synthesized by the palladium-catalyzed annulation of a variety of internal alkynes, in which two new carbon-carbon bonds are formed in a single step under relatively mild reaction conditions. This method has also been used to synthesize carbazoles, although a higher reaction temperature is necessary. The process involves arylpalladation of the alkyne, followed by intramolecular Heck olefination and double bond isomerization. This method accommodates a variety of functional groups and affords the anticipated highly substituted naphthalenes and carbazoles in good to excellent yields. Novel palladium migratiodarylation methodology for the synthesis of complex fused polycycles has been developed, in which one or more sequential Pd-catalyzed intramolecular migration processes involving C-H activation are employed. The chemistry works best with electron-rich aromatics, which is in agreement

  10. New Palladium-Catalyzed Approaches to Heterocycles and Carbocycles

    Energy Technology Data Exchange (ETDEWEB)

    Qinhua Huang

    2004-12-19

    The tert-butylimines of o-(1-alkynyl)benzaldehydes and analogous pyridinecarbaldehydes have been cyclized under very mild reaction conditions in the presence of I{sub 2}, ICl, PhSeCl, PhSCl and p-O{sub 2}NC{sub 6}H{sub 4}SCl to give the corresponding halogen-, selenium- and sulfur-containing disubstituted isoquinolines and naphthyridines, respectively. Monosubstituted isoquinolines and naphthyridines have been synthesized by the metal-catalyzed ring closure of these same iminoalkynes. This methodology accommodates a variety of iminoalkynes and affords the anticipated heterocycles in moderate to excellent yields. The Pd(II)-catalyzed cyclization of 2-(1-alkynyl)arylaldimines in the presence of various alkenes provides an efficient way to synthesize a variety of 4-(1-alkenyl)-3-arylisoquinolines in moderate to excellent yields. The introduction of an ortho-methoxy group on the arylaldimine promotes the Pd-catalyzed cyclization and stabilizes the resulting Pd(II) intermediate, improving the yields of the isoquinoline products. Highly substituted naphthalenes have been synthesized by the palladium-catalyzed annulation of a variety of internal alkynes, in which two new carbon-carbon bonds are formed in a single step under relatively mild reaction conditions. This method has also been used to synthesize carbazoles, although a higher reaction temperature is necessary. The process involves arylpalladation of the alkyne, followed by intramolecular Heck olefination and double bond isomerization. This method accommodates a variety of functional groups and affords the anticipated highly substituted naphthalenes and carbazoles in good to excellent yields. Novel palladium migratiodarylation methodology for the synthesis of complex fused polycycles has been developed, in which one or more sequential Pd-catalyzed intramolecular migration processes involving C-H activation are employed. The chemistry works best with electron-rich aromatics, which is in agreement with the idea that

  11. Recent advances in copper-catalyzed asymmetric coupling reactions

    Directory of Open Access Journals (Sweden)

    Fengtao Zhou

    2015-12-01

    Full Text Available Copper-catalyzed (or -mediated asymmetric coupling reactions have received significant attention over the past few years. Especially the coupling reactions of aryl or alkyl halides with nucleophiles became a very powerful tool for the formation of C–C, C–N, C–O and other carbon–heteroatom bonds as well as for the construction of heteroatom-containing ring systems. This review summarizes the recent progress in copper-catalyzed asymmetric coupling reactions for the formation of C–C and carbon–heteroatom bonds.

  12. The mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol

    Institute of Scientific and Technical Information of China (English)

    竹湘锋; 徐新华

    2004-01-01

    Fe (Ⅲ)-catalyzed ozonation yielded better degradation rate and extent of COD (Chemical Oxygen Demand) or oxalic acid as compared with oxidation by ozone alone. Two parameters with strong effects on the efficiency of ozonation are pH of the solution and the catalyst (Fe3+) dosage. The existence of a critical pH value determining the catalysis of Fe (Ⅲ) in acid conditions was observed in phenol and oxalic acid systems. The best efficiency of catalysis was obtained at a moderate concentration of the catalyst. A reasonable mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol was obtained based on the results and literature.

  13. Esterification of phenolic acids catalyzed by lipases immobilized in organogels.

    Science.gov (United States)

    Zoumpanioti, M; Merianou, E; Karandreas, T; Stamatis, H; Xenakis, A

    2010-10-01

    Lipases from Rhizomucor miehei and Candida antarctica B were immobilized in hydroxypropylmethyl cellulose organogels based on surfactant-free microemulsions consisting of n-hexane, 1-propanol and water. Both lipases kept their catalytic activity, catalyzing the esterification reactions of various phenolic acids including cinnamic acid derivatives. High reaction rates and yields (up to 94%) were obtained when lipase from C. antarctica was used. Kinetic studies have been performed and apparent kinetic constants were determined showing that ester synthesis catalyzed by immobilized lipases occurs via the Michaelis-Menten mechanism.

  14. Graphene oxide catalyzed cis-trans isomerization of azobenzene

    Directory of Open Access Journals (Sweden)

    Dongha Shin

    2014-09-01

    Full Text Available We report the fast cis-trans isomerization of an amine-substituted azobenzene catalyzed by graphene oxide (GO, where the amine functionality facilitates the charge transfer from azobenzene to graphene oxide in contrast to non-substituted azobenzene. This catalytic effect was not observed in stilbene analogues, which strongly supports the existence of different isomerization pathways between azobenzene and stilbene. The graphene oxide catalyzed isomerization is expected to be useful as a new photoisomerization based sensing platform complementary to GO-based fluorescence quenching methods.

  15. Cyclodextrin-Catalyzed Organic Synthesis: Reactions, Mechanisms, and Applications

    Directory of Open Access Journals (Sweden)

    Chang Cai Bai

    2017-09-01

    Full Text Available Cyclodextrins are well-known macrocyclic oligosaccharides that consist of α-(1,4 linked glucose units and have been widely used as artificial enzymes, chiral separators, chemical sensors, and drug excipients, owing to their hydrophobic and chiral interiors. Due to their remarkable inclusion capabilities with small organic molecules, more recent interests focus on organic reactions catalyzed by cyclodextrins. This contribution outlines the current progress in cyclodextrin-catalyzed organic reactions. Particular emphases are given to the organic reaction mechanisms and their applications. In the end, the future directions of research in this field are proposed.

  16. Preparation of ethoxylated fatty alcohol carboxylate by catalytic oxidation and its blending performance%催化氧化制备醇醚羧酸盐及其复配性能研究

    Institute of Scientific and Technical Information of China (English)

    张望; 李秋小; 李运玲

    2009-01-01

    以脂肪醇聚氧乙烯醚(AEO9)、氧气和氢氧化钠为原料,在自制的Pd/C催化剂作用下催化氧化制备醇醚羧酸盐(AE9C)阴离子表面活性剂.考察了反应条件对产品收率的影响,并研究了AE9C与双癸基二甲基氯化铵(DDMAC10)复配体系的润湿、乳化和泡沫性能.结果表明较佳的反应条件为:温度70℃、压力0.08 Mpa、反应时间4 h,产品的收率可达85%.AE9C与DDMAC10复配具有较好的协同效应.%Ethoxylated fatty alcohol carboxylate (AE9C), an anionic surfactant was synthesized by using AEO9, O2 and NaOH as starting materials with self-made Pd/C catalyst. Reaction conditions were investigated. AE9C product was blended with didecyldimethylammonium chloride (DDMAC10). The properties of the blended surfactant, such as foaming power, wetting power and emulsifying power were measured. The experiment results showed that the optimum reaction conditions to prepare AE9C are temperature 70 ℃;pressure 0.08 Mpa;reaction time 4 h. Yield up to 85% can be achieved. The performance of the blended surfactant of AE9C with DDMAC10 showed that such blending has significant synergistic effect.

  17. Rheology of Lamellar Liquid Crystal Formed from Nonyl Phenol Ethoxylate(10) and Water%壬基酚聚氧乙烯醚(10)/水体系层状液晶的流变性

    Institute of Scientific and Technical Information of China (English)

    冯尚华; 张翠娟; 李衍飞

    2012-01-01

    采用应力控制流变仪,研究了非离子表面活性剂壬基酚聚氧乙烯醚(10)(NP-10)/水体系层状液晶在不同温度和表面活性剂质量分数的流变性.在线性黏弹区内,其储能模量和损耗模量与频率的关系不符合Maxwell模型,并用滑移模型、范德华力、水化作用解释了非离子表面活性剂层状液晶表现此类流变性的原因;用Burgers模型解释了蠕变-回复实验的结论,其结果与线性的振荡实验一致.%The rheological behavior of a lamellar lyotropic liquid crystal formed from nonyl phenol ethoxylate (10) (NP-10)/water was investigated using a rheometer. The influence of composition and temperature on the dynamic function was studied at varied surfactant concentration and temperature. The frequency-dependent storage and loss modulus were found not to be consistent with the Maxwell model in the linear viscoelastic region. The results were analyzed on the basis of slip-plane theory. The compliance was also measured, and the instantaneous elasticity measured in the creep tests was in according with the oscillatory tests. Burgers model was used to describe the time-dependent compliance.

  18. Lipase-Catalyzed Aza-Michael Reaction on Acrylate Derivatives

    NARCIS (Netherlands)

    Steunenberg, P.; Sijm, M.; Zuilhof, H.; Sanders, J.P.M.; Scott, E.L.; Franssen, M.C.R.

    2013-01-01

    A methodology has been developed for an efficient and selective lipase-catalyzed aza-Michael reaction of various amines (primary and secondary) with a series of acrylates and alkylacrylates. Reaction parameters were tuned, and under the optimal conditions it was found that Pseudomonas stutzeri lipas

  19. Rh-Catalyzed Asymmetric Hydrogenation of 1,2-Dicyanoalkenes.

    Science.gov (United States)

    Li, Meina; Kong, Duanyang; Zi, Guofu; Hou, Guohua

    2017-01-06

    A highly efficient enantioselective hydrogenation of 1,2-dicyanoalkenes catalyzed by the complex of rhodium and f-spiroPhos has been developed. A series of 1,2-dicyanoalkenes were successfully hydrogenated to the corresponding chiral 1,2-dicyanoalkanes under mild conditions with excellent enantioselectivities (up to 98% ee). This methodology provides efficient access to the asymmetric synthesis of chiral diamines.

  20. Asymmetric Catalytic Reactions Catalyzed by Chiral Titanium Complexes

    Institute of Scientific and Technical Information of China (English)

    FENG XiaoMing

    2001-01-01

    @@ Chiral titanium complexes is very importance catalyst to asymmetric catalytic reactions. A series of catalytic systems based on titanium-chiral ligands complexes has been reported. This presentation will discuss some of our recent progress on asymmetric catalytic reactions catalyzed by chiral titanium complexes.

  1. Asymmetric Catalytic Reactions Catalyzed by Chiral Titanium Complexes

    Institute of Scientific and Technical Information of China (English)

    FENG; XiaoMing

    2001-01-01

    Chiral titanium complexes is very importance catalyst to asymmetric catalytic reactions. A series of catalytic systems based on titanium-chiral ligands complexes has been reported. This presentation will discuss some of our recent progress on asymmetric catalytic reactions catalyzed by chiral titanium complexes.  ……

  2. Recent developments in gold-catalyzed cycloaddition reactions

    Directory of Open Access Journals (Sweden)

    Fernando López

    2011-08-01

    Full Text Available In the last years there have been extraordinary advances in the development of gold-catalyzed cycloaddition processes. In this review we will summarize some of the most remarkable examples, and present the mechanistic rational underlying the transformations.

  3. Palladium-Catalyzed alpha-Arylation of Tetramic Acids

    DEFF Research Database (Denmark)

    Storgaard, Morten; Dorwald, F. Z.; Peschke, B.;

    2009-01-01

    A mild, racemization-free, palladium-Catalyzed alpha-arylation of tetramic acids (2,4-pyrrolidinediones) has been developed. Various amino acid-derived tetramic acids were cleanly arylated by treatment with 2 mol % of Pd(OAc)(2), 4 mol % of a sterically demanding biaryl phosphine, 2.3 equiv of K2CO...

  4. DNA strand exchange catalyzed by molecular crowding in PEG solutions

    KAUST Repository

    Feng, Bobo

    2010-01-01

    DNA strand exchange is catalyzed by molecular crowding and hydrophobic interactions in concentrated aqueous solutions of polyethylene glycol, a discovery of relevance for understanding the function of recombination enzymes and with potential applications to DNA nanotechnology. © 2010 The Royal Society of Chemistry.

  5. ASYMMETRIC HYDROSILYLATION CATALYZED BY POLYMER—SUPPORTED THIAZOLIDINE RHODIUM CATALYSTS

    Institute of Scientific and Technical Information of China (English)

    LEIYanohui; LIHong; 等

    1999-01-01

    Asymmetric hydrisilylation catalyzed by polymeric thiazolidine rhodium catalysts was conducted.Almost the same optical yields have been obtained when comb-shaped polymeric ligands and their corresponding monomer complexed rhodium cataltysts were used to asymmetric hydrosilylation of acetophenone.Optical yield of chiral 1-methylbenzyl alcohol reaches as high as 71.5%.Temperature dependence of enantioselective hydrosilylation of acetophenone was discussed.

  6. Palladium-catalyzed silylation of aryl chlorides with hexamethyldisilane.

    Science.gov (United States)

    McNeill, Eric; Barder, Timothy E; Buchwald, Stephen L

    2007-09-13

    A method for the palladium-catalyzed silylation of aryl chlorides has been developed. The method affords desired product in good yield, is tolerant of a variety of functional groups, and provides access to a wide variety of aryltrimethylsilanes from commercially available aryl chlorides. Additionally, a one-pot procedure that converts aryl chlorides into aryl iodides has been developed.

  7. Solvent-free lipase-catalyzed preparation of diacylglycerols.

    Science.gov (United States)

    Weber, Nikolaus; Mukherjee, Kumar D

    2004-08-25

    Various methods have been applied for the enzymatic preparation of diacylglycerols that are used as dietary oils for weight reduction in obesity and related disorders. Interesterification of rapeseed oil triacylglycerols with commercial preparations of monoacylglycerols, such as Monomuls 90-O18, Mulgaprime 90, and Nutrisoft 55, catalyzed by immobilized lipase from Rhizomucor miehei (Lipozyme RM IM) in vacuo at 60 degrees C led to extensive (from 60 to 75%) formation of diacylglycerols. Esterification of rapeseed oil fatty acids with Nutrisoft, catalyzed by Lipozyme RM in vacuo at 60 degrees C, also led to extensive (from 60 to 70%) formation of diacylglycerols. Esterification of rapeseed oil fatty acids with glycerol in vacuo at 60 degrees C, catalyzed by Lipozyme RM and lipases from Thermomyces lanuginosus (Lipozyme TL IM) and Candida antarctica (lipase B, Novozym 435), also provided diacylglycerols, however, to a lower extent (40-45%). Glycerolysis of rapeseed oil triacylglycerols with glycerol in vacuo at 60 degrees C, catalyzed by Lipozyme TL and Novozym 435, led to diacylglycerols to the extent of

  8. N-heterocyclic carbene catalyzed direct carbonylation of dimethylamine.

    Science.gov (United States)

    Li, Xiaonian; Liu, Kun; Xu, Xiaoliang; Ma, Lei; Wang, Hong; Jiang, Dahao; Zhang, Qunfeng; Lu, Chunshan

    2011-07-21

    N-Heterocyclic carbene (NHC) catalyzed direct carbonylation of dimethylamine leading to the formation of DMF was successfully accomplished under metal-free conditions. The catalytic efficiency was investigated and the turnover numbers can reach as high as >300. The possible mechanism was also proposed.

  9. Kinetic Resolution of Aryl Alkenylcarbinols Catalyzed by Fc-PIP

    Institute of Scientific and Technical Information of China (English)

    胡斌; 孟萌; 姜山山; 邓卫平

    2012-01-01

    An effective kinetic resolution of a variety of aryl alkenylcarbinols catalyzed by nonenzymatic acyl transfer catalyst Fe-PIP was developed, affording corresponding unreacted alcohols in good to excellent ee value up to 99% and with selectivity factors up to 24.

  10. Iron-Catalyzed Synthesis of Sulfur-Containing Heterocycles.

    Science.gov (United States)

    Bosset, Cyril; Lefebvre, Gauthier; Angibaud, Patrick; Stansfield, Ian; Meerpoel, Lieven; Berthelot, Didier; Guérinot, Amandine; Cossy, Janine

    2016-10-13

    An iron-catalyzed synthesis of sulfur- and sulfone-containing heterocycles is reported. The method is based on the cyclization of readily available substrates and proceeded with high efficiency and diastereoselectivity. A variety of sulfur-containing heterocycles bearing moieties suitable for subsequent functionalization are prepared. Illustrative examples of such postcyclization modifications are also presented.

  11. Lipase-Catalyzed Modification of Canola Oil with Caprylic Acid

    DEFF Research Database (Denmark)

    Wang, Yingyao; Luan, Xia; Xu, Xuebing

    Lipase-catalyzed acidolysis of canola oil with caprylic acid was performed to produce structured lipids. Six commercial lipases from different sources were screened for their ability to incorporate the caprylic acid into the canola oil. The positional distribution of FA on the glycerol backbone o...

  12. Gal3 Catalyzed Tetrahydropyranylation of Alcohols and Phenols

    Institute of Scientific and Technical Information of China (English)

    SUN, Pei-Pei(孙培培); HU, Zhi-Xin(胡志新)

    2004-01-01

    In dichloromethane, the nucleophilic addition of alcohols or phenols to 3,4-dihydro-2H-pyran (DHP) was catalyzed effectively by gallium triiodide which was generated in situ by the reaction of gallium metal and iodine to give the corresponding tetrahydropyranyl acetals in good to excellent yields.

  13. Catalyzing new product adoption at the base of the pyramid

    NARCIS (Netherlands)

    Marinakis, Y.D.; Walsh, S.T.; Harms, R.

    2016-01-01

    One of the more perplexing of the entrepreneurial issues at the Base of the Pyramid (BoP) is how to catalyze new product adoption by BoP consumers. Because S-shaped adoption dynamics are the result of cultural transmission bias, the question can be rephrased as, how can an entrepreneur overcome conf

  14. Transfer Methane to Fragrant Hydrocarbon by Direct Catalyzed Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Sponsored by NSFC,a research project -"Transfer methane to fragrant hydrocarbon by direct catalyzed dehydrogenation",directed by Prof.Xin Bao from Dalian Institute of Chemical Physics of CAS,honored the 2nd class National Science & Technology Award in 2005.

  15. Rh-Catalyzed arylation of fluorinated ketones with arylboronic acids.

    Science.gov (United States)

    Dobson, Luca S; Pattison, Graham

    2016-09-25

    The Rh-catalyzed arylation of fluorinated ketones with boronic acids is reported. This efficient process allows access to fluorinated alcohols in high yields under mild conditions. Competition experiments suggest that difluoromethyl ketones are more reactive than trifluoromethyl ketones in this process, despite their decreased electronic activation, an effect we postulate to be steric in origin.

  16. Rhodium catalyzed arylation of diazo compounds with aryl boronic acids.

    Science.gov (United States)

    Ghorai, Jayanta; Anbarasan, Pazhamalai

    2015-04-03

    A general and efficient synthesis of diarylacetate, a diarylmethine derivative, was accomplished through rhodium catalyzed direct arylation of diazo compounds with arylboronic acids. The reaction tolerates various boronic acid derivatives and functional groups. Notably, chemoselective arylation of diazo compounds over other electrophiles were demonstrated. The efficacy of the developed methodology is shown by the expeditious synthesis of the core structure of diclofensine.

  17. Palladium-catalyzed enantioselective conjugate addition of arylboronic acids

    NARCIS (Netherlands)

    Gini, F; Hessen, B; Minnaard, AJ

    2005-01-01

    The first asymmetric palladium-catalyzed conjugate addition of arylboronic acids to alpha,beta-unsaturated aldehydes, ketones, and esters is described. For cyclic substrates, excellent chemo-, regio-, and enantioselectivities are achieved when a Pd(O2CCF3)(2)/DuPHOS catalyst is applied.

  18. Amylase catalyzed synthesis of glycosyl acrylates and their polymerization

    NARCIS (Netherlands)

    Kloosterman, Wouter M.J.; Jovanovic, Danijela; Brouwer, Sander; Loos, Katja

    2014-01-01

    The enzymatic synthesis of novel (di)saccharide acrylates from starch and 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and 4-hydroxybutyl acrylate (2-HEA, 2-HEMA and 4-HBA) catalyzed by various commercially available amylase preparations is demonstrated. Both liquefaction and saccharificatio

  19. Enantioselective N-heterocyclic carbene-catalyzed synthesis of trifluoromethyldihydropyridinones.

    Science.gov (United States)

    Wang, Dong-Ling; Liang, Zhi-Qin; Chen, Kun-Quan; Sun, De-Qun; Ye, Song

    2015-06-05

    The enantioselective N-heterocyclic carbene-catalyzed [4 + 2] cyclocondensation of α-chloroaldehydes and trifluoromethyl N-Boc azadienes was developed, giving the corresponding 3,4-disubstituted-6-trifluoromethyldihydropyridin-2(1H)-ones in good yields with exclusive cis-selectivities and excellent enantioselectivities.

  20. ReBr(CO)5-Catalyzed Knoevenagel Condensation

    Institute of Scientific and Technical Information of China (English)

    ZUO Wei-xiong; HUA Rui-mao; SUN Hong-bin

    2004-01-01

    Knoevenagel condensations are especially important reactions for the synthesis of alkene compounds having electron-withdrawing groups such as COR,CN,COOR,NO2 etc. Recently,transition metal hydride ruthenium1, hydride and polyhydride rhenium2, and polyhydride iridium complexes have been found to be the efficient catalysts for Knoevenagle condensation. However the mentioned-above transition metal hydride complexes are not easily prepared. In addition, all of them are oxygen and H2O-sensitive, unstable compands. Therefor the catalytic reactions are required to be carried out under an inert atmosphere, and using the prepurified reagent.In the paper, We wish to report the development of Knoevenagel condensation catalyzed by ReBr(CO)5 under an air atmosphere in the absence of solvent.All the experiments were carried out under 1atm, without solvent.The resuIts of the representative Knoevenagel condensations are summarized in Table 1.The Knoevenagel reaction with diethyl malonate can be catalyzed by ReBr(CO)5, while the present Knoevenagel reactions catalyzed by transition metal have at least one cyano group in active methylene compouds.A propose mechanism for present catalytic coupling dehydration reactions is also illustrated in the paper.Briefly, this paper reports the ReBr(CO)5-catalyzed Knoevenagel reaction. The reaction is a new method for the Konevenagel condensation.

  1. Phosphine-catalyzed [3+2] annulation of cyanoallenes

    NARCIS (Netherlands)

    Kinderman, S.S.; van Maarseveen, J.H.; Hiemstra, H.

    2011-01-01

    Cyanoallenes were successfully used in organophosphine-catalyzed [3+2]-type annulation to give cyano-substituted dihydropyrroles in good yield. Chiral phosphines were also screened, leading to some initial results in the asymmetric version of cyano­allene-based annulations.

  2. Platinum-catalyzed hydroformylation of terminal and internal octenes

    NARCIS (Netherlands)

    van Duren, R.; van der Vlugt, J.I.; Kooijman, H.; Spek, A.L.; Vogt, D.

    2007-01-01

    A brief historic overview of Pt/Sn-catalyzed hydroformylation as well as recent advances in the hydroformylation of internal alkenes is provided. This serves as background for the results obtained with the [Pt(Sixantphos)Cl2] system, for which the molecular structure and the spectroscopic data are

  3. Synthesis of lactams using enzyme-catalyzed aminolysis

    NARCIS (Netherlands)

    Stavila, E.; Loos, K.

    2013-01-01

    The formation of e-caprolactam from 6-aminocaproic acid catalyzed by CALB (N435) is reported. Different lactam ring sizes can be prepared starting from 4-aminobutanoic acid, 5-aminovaleric acid, and 8-aminooctanoic acid. Experiments with mixtures of aminocarboxylic acids have shown that CALB prefers

  4. Computational Studies on Cinchona Alkaloid-Catalyzed Asymmetric Organic Reactions.

    Science.gov (United States)

    Tanriver, Gamze; Dedeoglu, Burcu; Catak, Saron; Aviyente, Viktorya

    2016-06-21

    Remarkable progress in the area of asymmetric organocatalysis has been achieved in the last decades. Cinchona alkaloids and their derivatives have emerged as powerful organocatalysts owing to their reactivities leading to high enantioselectivities. The widespread usage of cinchona alkaloids has been attributed to their nontoxicity, ease of use, stability, cost effectiveness, recyclability, and practical utilization in industry. The presence of tunable functional groups enables cinchona alkaloids to catalyze a broad range of reactions. Excellent experimental studies have extensively contributed to this field, and highly selective reactions were catalyzed by cinchona alkaloids and their derivatives. Computational modeling has helped elucidate the mechanistic aspects of cinchona alkaloid catalyzed reactions as well as the origins of the selectivity they induce. These studies have complemented experimental work for the design of more efficient catalysts. This Account presents recent computational studies on cinchona alkaloid catalyzed organic reactions and the theoretical rationalizations behind their effectiveness and ability to induce selectivity. Valuable efforts to investigate the mechanisms of reactions catalyzed by cinchona alkaloids and the key aspects of the catalytic activity of cinchona alkaloids in reactions ranging from pharmaceutical to industrial applications are summarized. Quantum mechanics, particularly density functional theory (DFT), and molecular mechanics, including ONIOM, were used to rationalize experimental findings by providing mechanistic insights into reaction mechanisms. B3LYP with modest basis sets has been used in most of the studies; nonetheless, the energetics have been corrected with higher basis sets as well as functionals parametrized to include dispersion M05-2X, M06-2X, and M06-L and functionals with dispersion corrections. Since cinchona alkaloids catalyze reactions by forming complexes with substrates via hydrogen bonds and long

  5. Synthesis of Sorbitolum ethoxylates oleate with active carbon supported p-toluene sulphonic acid as catalyst%活性炭负载对甲苯磺酸催化合成山梨醇聚氧乙烯醚油酸酯

    Institute of Scientific and Technical Information of China (English)

    刘志湘; 钱建芳; 王月芬; 谢专

    2013-01-01

    以活性炭负载对甲苯磺酸作催化剂,山梨醇聚氧乙烯醚和油酸为原料,合成山梨醇聚氧乙烯醚油酸酯.考察了催化剂用量、反应温度、反应时间等条件对反应的影响.较优的合成条件为:真空脱水,催化剂用量为总物质量的0.25%,反应温度为130 ~135℃,反应时间为3.0h,满足指标要求.%Using p-toluensulphonic acid supported by activated carbon as catalyst, Sorbitolum ethoxylates oleate was synthesized from Sorbitolum ethoxylates and oleic acid. The effect of reaction conditions inclu-ding catalyst amount, reaction temperature, reaction time on esterification were investigated. The optimum synthesis conditions were as follows: vacuum dehydration, the amount of catalyst 0.25% base on the total mass of reactants, the reaction temperature 130~135℃, the reaction time 3.0 h, to meet the target re-quirements.

  6. Synthesis and hydrolysis resisting capacity of ethoxylated ricinoleic acid methyl esters%蓖麻油酸甲酯乙氧基化物的合成与耐酸耐碱性研究

    Institute of Scientific and Technical Information of China (English)

    张谦; 孙永强; 王万绪; 智丽飞; Martino Di Serio; 刘伟

    2015-01-01

    Ethoxylated ricinoleic acid methyl esters (ECAME - 10)obtained directly from castor oil acid methyl esters by the use of a special homogeneous catalyst. The average ethylene oxide (EO)adduct number of ECAME - 10 was determined by saponification value,gas chromatography (GC)and 1 HNMR. The hydrolysis resisting capacity of ECAME - 10 was investigated under different pH value conditions. The appearance changes of ECAME - 10 solution under different storing time periods was tracked and photographed and surface tension of different stages of the solution at different stages was measured. Results showed that the hydrolysis resisting capacity of ECAME - 10 is rather strong. The hydrolysis rate of ECAME - 10 is below 40% in pH value range of 4 - 9 after eight weeks. Surface tension of solutions can be kept stable after the hydrolysis reaction.%在一定的温度和压力条件下,以及特制的均相催化剂作用下,直接由蓖麻油酸甲酯得到了产物蓖麻油酸甲酯乙氧基化物(ECAME -10)。通过皂化值、气相色谱(GC)和1 HNMR 测定了ECAME -10的平均环氧乙烷(EO)加合数,在不同pH条件下测定了ECAME -10的耐酸耐碱性,并跟踪拍摄了不同pH溶液不同阶段的外观照片,同时测定了不同阶段溶液的表面张力。结果显示:ECAME -10有较强的抗水解能力,当pH =4~9时,ECAME -10的水解较慢,8周后其水解率在40%以下;水解后的表面张力数据表明,水解后溶液的表面张力可保持稳定。

  7. 羟乙基化双酚A环氧树脂的合成与性能研究%Synthesis and properties of diglycidyl ether of ethoxylated bisphenol-A

    Institute of Scientific and Technical Information of China (English)

    何佩佩; 杨欣; 黄伟

    2013-01-01

    A low viscosity epoxy resin named diglycidyl ether of ethoxylated bisphenol-A (DGEBAEO-2.25)was synthesized by one-step method using solid sodium hydroxide as catalyst.The structure of DGEBAEO-2.25 was characterized by FT-IR,1H-NMR,and GPC.The DGEBAEO-2.25 was cured by 4,4'-diamino diphenyl sulfone (DDS).The viscosity,curing reactivity,thermal and mechanical properties of the DGEBAEO-2.25 system were investigated by comparison with the diglycidyl ether of bisphenol-A (DGEBA,epoxy value 0.51) system.The results showed that DGEBAEO-2.25 had lower viscosity which was one seventh of DGEBA and the curing reactivity and glass transition temperature were lower than that of DGEBA.The toughness of the cured product was significantly improved and the impact strength was two times higher than that of DGEBA.The tensile,flexural strength and modulus were essentially unchanged.%使用固体NaOH为催化剂,通过一步法合成了低粘度的羟乙基化双酚A环氧树脂(DGEBAEO-2.25),并利用FT-IR,1H-NMR,GPC对产物的结构进行了表征.采用4,4’-二氨基二苯砜(DDS)固化DGEBAEO-2.25,通过与双酚A环氧树脂(DGEBA,环氧值0.51)体系的比较,研究了DGEBAEO-2.25体系的粘度、固化活性、热性能及力学性能.结果表明,DGEBAEO-2.25的粘度仅为DGEBA的1/7;固化活性及玻璃化温度降低;固化物韧性明显提高,冲击强度提高2倍多,且拉伸、弯曲强度和模量基本保持不变.

  8. 塑料食包材料烷基酚聚氧乙烯醚迁移量的测定%Migration Determination of Alkyl Phenol Ethoxylates in Plastic Food Contact Materials

    Institute of Scientific and Technical Information of China (English)

    杨菁; 闫婧; 吕刚; 周磊

    2015-01-01

    A new analytical method based on high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) was developed for determining the migration of alkyl phenol ethoxylates from plastic food packaging materials into food simulants such as water , 3 % acetic acid solution (weight fraction), 10%ethanol solution (volume fraction), 95%ethanol solution (volume fraction)and olive oil. The contact with food simulants tests were carried out at 40 ℃ for 240 h. The anlalytes were separated on a C 18 column using 3 %acetonitrile -77 %methanol -20 %water (volume fraction) as mobile phase, and then detected by HPLC-MS/MS using selective reaction monitoring (SRM) mode. The recoveries for nonylphenol polyethoxylates varied from 72.9%to 104.6%with the relative standard deviations ranging from 1.5%to 11.2%. The recoveries for octylphenol polyethoxylates varied from 94.9 % to 113.9 % with the relative standard deviations ranging from 2.6%to 7.0%.%建立了高效液相色谱串联质谱法对塑料食品包装材料中烷基酚聚氧乙烯醚向食品模拟物迁移量的检测方法。使用5种食品模拟物:水、3%乙酸溶液(质量分数)、10%的乙醇溶液(体积分数)、95%的乙醇溶液(体积分数)和橄榄油。样品在40℃下浸泡240 h,以C18柱为分离柱,3%乙腈-77%甲醇-20%水为流动相分离,采用电喷雾串联四级杆进行检测。该方法对壬基酚聚氧乙烯醚的平均回收率为72.9%~104.6%,相对标准偏差为1.5%~11.2%,对辛基酚聚氧乙烯醚的平均回收率为94.9%~113.9%,相对标准偏差为2.6%~7.0%。

  9. The Characterization and Hydrogen Production from Water Decomposition with Methanol in a Semi-Batch Type Reactor Using In, P-TiO2s

    Directory of Open Access Journals (Sweden)

    Joonwoo Kim

    2011-01-01

    Full Text Available The photocatalytic production of hydrogen from water using solar energy is potentially a clean and renewable source for hydrogen fuel. This study examines the production of hydrogen over In, P-TiO2s photocatalysts. 1 mol% In-TiO2 and P-TiO2 were produced using the solvothermal method and were treated at 500 and 800∘C to obtain anatase and rutile structure, respectively. The photocatalysts were characterized by X-ray diffraction, photoluminescence spectra, X-ray spectroscopy, UV-visible spectroscopy, and scanning electron microscopy. The production of H2 from methanol photodecomposition was greater over the rutile structure than over the anatase structure of TiO2. Moreover, the amount of hydrogen was enhanced over In-TiO2 and P-TiO2 compared to that over pure TiO2; the production increased by about 30%. The structural effect and the addition of In, P have significant influence on the H2 production from methanol/water decomposition.

  10. Kinetic studies on hydrolysis of urea in a semi-batch reactor at atmospheric pressure for safe use of ammonia in a power plant for flue gas conditioning

    Energy Technology Data Exchange (ETDEWEB)

    Mahalik, K. [Department of Chemical Engineering, Indian Institute of Technology (IIT), Kharagpur, P.O. Kharagpur Technology, West Bengal 721302 (India); Department of Chemical Engineering, Gandhi Institute of Engineering and Technology, Gunupur, Orissa (India); Sahu, J.N., E-mail: jnsahu@um.edu.my [Department of Chemical Engineering, Indian Institute of Technology (IIT), Kharagpur, P.O. Kharagpur Technology, West Bengal 721302 (India); Department of Chemical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Patwardhan, Anand V. [Department of Chemical Engineering, Institute of Chemical Technology (ICT), Mumbai 400019 (India); Meikap, B.C. [Department of Chemical Engineering, Indian Institute of Technology (IIT), Kharagpur, P.O. Kharagpur Technology, West Bengal 721302 (India); School of Chemical Engineering, University of KwaZulu-Natal, Faculty of Engineering, Howard College Campus, King George V. Avenue, Durban 4041 (South Africa)

    2010-03-15

    With growing industrialization in power sector, air is being polluted with a host of substances-most conspicuously with suspended particulate matter emanating from coal-fired thermal power plants. Flue gas conditioning, especially in such power plants, requires in situ generation of ammonia. In the present paper, experiments for kinetic study of hydrolysis of urea have been conducted using a borosil glass reactor, first without stirring followed by with stirring. The study reveals that conversion increases exponentially with an increase in temperature and feed concentration. Furthermore, the effect of stirring speed, temperature and concentration on conversion has been studied. Using collision theory, temperature dependency of forward rate constant has been developed from which activation energy of the reaction and the frequency factors have been calculated. It has been observed that the forward rate constant increases with an increase in temperature. The activation energy and frequency factor with stirring has been found to be 59.85 kJ/mol and 3.9 x 10{sup 6} min{sup -1} respectively with correlation co-efficient and standard deviation being 0.98% and {+-}0.1% in that order.

  11. Thermodynamics of Enzyme-Catalyzed Reactions. Part 3. Hydrolases

    Science.gov (United States)

    Goldberg, Robert N.; Tewari, Yadu B.

    1994-11-01

    Equilibrium constants and enthalpy changes for reactions catalyzed by the hydrolase class of enzymes have been compiled. For each reaction the following information is given: The reference for the data; the reaction studied; the name of the enzyme used and its Enzyme Commission number; the method of measurement; the conditions of measurement [temperature, pH, ionic strength, and the buffer(s) and cofactor(s) used]; the data and an evaluation of it; and, sometimes, commentary on the data and on any corrections which have been applied to it or any calculations for which the data have been used. The data from 145 references have been examined and evaluated. Chemical Abstract Service registry numbers are given for the substances involved in these various reactions. There is a cross reference between the substances and the Enzyme Commission numbers of the enzymes used to catalyze the reactions in which the substances participate.

  12. Thermodynamics of Enzyme-Catalyzed Reactions: Part 4. Lyases

    Science.gov (United States)

    Goldberg, Robert N.; Tewari, Yadu B.

    1995-09-01

    Equilibrium constants and enthalpy changes for reactions catalyzed by the lyase class of enzymes have been compiled. For each reaction the following information is given: the reference for the data; the reaction studied; the name of the enzyme used and its Enzyme Commission number; the method of measurement; the conditions of measurement (temperature, pH, ionic strength, and the buffer(s) and cofactor(s) used); the data and an evaluation of it; and, sometimes, commentary on the data and on any corrections which have been applied to it or any calculations for which the data have been used. The data from 106 references have been examined and evaluated. Chemical Abstract Service registry numbers are given for the substances involved in these various reactions. There is a cross reference between the substances and the Enzyme Commission numbers of the enzymes used to catalyze the reactions in which the substances participate.

  13. Thermodynamics of Enzyme-Catalyzed Reactions: Part 2. Transferases

    Science.gov (United States)

    Goldberg, Robert N.; Tewari, Yadu B.

    1994-07-01

    Equilibrium constants and enthalpy changes for reactions catalyzed by the transferase class of enzymes have been compiled. For each reaction the following information is given: the reference for the data; the reaction studied; the name of the enzyme used and its Enzyme Commission number; the method of measurement; the conditions of measurement [temperature, pH, ionic strength, and the buffer(s) and cofactor(s) used]; the data and an evaluation of it; and, sometimes, commentary on the data and on any corrections which have been applied to it or any calculations for which the data have been used. The data from 285 references have been examined and evaluated. Chemical Abstract Service registry numbers are given for the substances involved in these various reactions. There is a cross reference between the substances and the Enzyme Commission numbers of the enzymes used to catalyze the reactions in which the substances participate.

  14. Mechanism of Intramolecular Rhodium- and Palladium-Catalyzed Alkene Alkoxyfunctionalizations

    KAUST Repository

    Vummaleti, Sai V. C.

    2015-11-13

    Density functional theory calculations have been used to investigate the reaction mechanism for the [Rh]-catalyzed intramolecular alkoxyacylation ([Rh] = [RhI(dppp)+] (dppp, 1,3-bis(diphenylphosphino)propane) and [Pd]/BPh3 dual catalytic system assisted intramolecular alkoxycyanation ([Pd] = Pd-Xantphos) using acylated and cyanated 2-allylphenol derivatives as substrates, respectively. Our results substantially confirm the proposed mechanism for both [Rh]- and [Pd]/ BPh3-mediated alkoxyfunctionalizations, offering a detailed geometrical and energetical understanding of all the elementary steps. Furthermore, for the [Rh]-mediated alkoxyacylation, our observations support the hypothesis that the quinoline group of the substrate is crucial to stabilize the acyl metal complex and prevent further decarbonylation. For [Pd]/BPh3-catalyzed alkoxycyanation, our findings clarify how the Lewis acid BPh3 cocatalyst accelerates the only slow step of the reaction, corresponding to the oxidative addition of the cyanate O-CN bond to the Pd center. © 2015 American Chemical Society.

  15. Microcalorimetric Study on Tyrosine Oxidation Catalyzed by Tyrosinase

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Through the method of initial heat release rate, the kinetic property of tyrosine oxidationcatalyzed by tyrosinase from Pseudomonas maltophilia was investigated using a LKB-2107 batchmicrocalorimeter. Tyrosine was catalyzed and oxidized into L-dopa, then into melanin catalyzed bytyrosinase. We found that the tyrosinase reaction obeyed the Michaelis-Menten kinetics, and at298.15K and pH 7.0, the initial exothermic rate (Ω0) are in the range of0.1567~0.5704 mJ@ s-1, themaximum exothermic rate (Ωmax) are in 0.4152 ~ 0.8143mol @ L-1, and mean value of the Michaelisconstant (Km) is 2.199±0.105×104 mol @ L-1.

  16. Polymerization of phenols catalyzed by peroxidase in nonaqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Dordick, J.S.; Marletta, M.A.; Klibanov, A.M.

    1987-01-01

    Polymers produced by horseradish-peroxidase-catalyzed coupling of phenols have been explored as potential substitutes for phenol-formaldehyde resins. To overcome low substrate solubilities and product molecular weights in water, enzymatic polymerizations in aqueous-organic mixtures have been examined. Peroxidase vigorously polymerizes a number of phenols in mixtures of water with water-miscible solvents such as dioxane, acetone, dimethylformamide, and methyl formate with the solvent content up to 95%. As a result, various phenolic polymers with average molecular weights from 400 to 2.6 x 10/sup 4/ D were obtained depending on the reaction medium composition and the nature of the phenol. Peroxidase-catalyzed copolymerization of different phenols in 85% dioxane was demonstrated. Poly(p-phenylphenol) and poly(p-cresol) were enzymatically prepared on a gram scale. They had much higher melting points, and in addition, poly(p-phenylphenol) was found to have a much higher electrical conductivity than phenol-formaldehyde resins.

  17. Effect of urate on the lactoperoxidase catalyzed oxidation of adrenaline.

    Science.gov (United States)

    Løvstad, Rolf A

    2004-12-01

    Lactoperoxidase is an iron containing enzyme, which is an essential component of the defense system of mammalian secretary fluids. The enzyme readily oxidizes adrenaline and other catecholamines to coloured aminochrome products. A Km-value of 1.21 mM and a catalytic constant (k = Vmax/[Enz]) of 15.5 x 10(3) min(-1) characterized the reaction between lactoperoxidase and adrenaline at pH 7.4. Urate was found to activate the enzyme catalyzed oxidation of adrenaline in a competitive manner, the effect decreasing with increasing adrenaline concentration. Lactoperoxidase was able to catalyze the oxidation of urate. However, urate was a much poorer substrate than adrenaline, and it seems unlikely that urate activates by functioning as a free, redox cycling intermediate between enzyme and adrenaline. The activation mechanism probably involves an urate-lactoperoxidase complex.

  18. Silylation of Dinitrogen Catalyzed by Hydridodinitrogentris(TriphenylphosphineCobalt(I

    Directory of Open Access Journals (Sweden)

    Wojciech I. Dzik

    2016-07-01

    Full Text Available Recently, homogeneous cobalt systems were reported to catalyze the reductive silylation of dinitrogen. In this study the investigations on the silylation of dinitrogen catalyzed by CoH(PPh33N2 are presented. We show that in the presence of the title compound, the reaction of N2 with trimethylsilylchloride and sodium yields, on average, 6.7 equivalents of tris(trimethylsilylamine per Co atom in THF (tetrahydrofuran. The aim was to elucidate whether the active catalyst is: (a the [Co(PPh33N2]− anion formed after two-electron reduction of the title compound; or (b a species formed via decomposition of CoH(PPh33N2 in the presence of the highly reactive substrates. Time profile, and IR and EPR spectroscopic investigations show instability of the pre-catalyst under the applied conditions which suggests that the catalytically active species is formed through in situ modification of the pre-catalyst.

  19. Cell-surface acceleration of urokinase-catalyzed receptor cleavage

    DEFF Research Database (Denmark)

    Høyer-Hansen, G; Ploug, M; Behrendt, N;

    1997-01-01

    937 cell lysates, had the same amino termini as uPAR(2+3), generated by uPA in a purified system. In both cases cleavage had occurred at two positions in the hinge region connecting domain 1 and 2, between Arg83-Ala84 and Arg89-Ser90, respectively. The uPA-catalyzed cleavage of uPAR is a new negative...

  20. Copper-catalyzed arylation of alkyl halides with arylaluminum reagents

    Directory of Open Access Journals (Sweden)

    Bijay Shrestha

    2015-12-01

    Full Text Available We report a Cu-catalyzed coupling between triarylaluminum reagents and alkyl halides to form arylalkanes. The reaction proceeds in the presence of N,N,N’,N’-tetramethyl-o-phenylenediamine (NN-1 as a ligand in combination with CuI as a catalyst. This catalyst system enables the coupling of primary alkyl iodides and bromides with electron-neutral and electron-rich triarylaluminum reagents and affords the cross-coupled products in good to excellent yields.

  1. Pd-catalyzed nucleophilic fluorination of aryl bromides.

    Science.gov (United States)

    Lee, Hong Geun; Milner, Phillip J; Buchwald, Stephen L

    2014-03-12

    On the basis of mechanism-driven reaction design, a Pd-catalyzed nucleophilic fluorination of aryl bromides and iodides has been developed. The method exhibits a broad substrate scope, especially with respect to nitrogen-containing heteroaryl bromides, and proceeds with minimal formation of the corresponding reduction products. A facilitated ligand modification process was shown to be critical to the success of the reaction.

  2. Gold-catalyzed oxidative cycloadditions to activate a quinoline framework.

    Science.gov (United States)

    Huple, Deepak B; Ghorpade, Satish; Liu, Rai-Shung

    2013-09-23

    Going for gold! Gold-catalyzed reactions of 3,5- and 3,6-dienynes with 8-alkylquinoline oxides results in an oxidative cycloaddition with high stereospecificity (see scheme; EWG = electron-withdrawing group); this process involves a catalytic activation of a quinoline framework. The reaction mechanism involves the intermediacy of α-carbonyl pyridinium ylides (I) in a concerted [3+2]-cycloaddition with a tethered alkene.

  3. Synthesis of Optically Active Polystyrene Catalyzed by Monophosphine Pd Complexes.

    Science.gov (United States)

    Jouffroy, Matthieu; Armspach, Dominique; Matt, Dominique; Osakada, Kohtaro; Takeuchi, Daisuke

    2016-07-11

    Cationic Pd(II) monophosphine complexes derived from α- and β-cyclodextrins (CDs) promote the homopolymerization of styrene under carbon monoxide pressure. Although reversible CO coordination takes place under catalytic conditions according to (13) C NMR studies with (13) C-enriched CO, both complexes catalyze the formation of CO-free styrene polymers. These macromolecules display optical activity as a result of the presence of stereoregular sequences within the overall atactic polymer.

  4. Copper-catalyzed Decarboxylative Hydroboration: Synthesis of Vinyl Boronic Esters

    Energy Technology Data Exchange (ETDEWEB)

    Irudayanathan, Francis Mariaraj; Raja, Gabriel Charles Edwin; Kim, Han-Sung; Na, Kyungsu; Lee, Sunwoo [Chonnam National University, Gwangju (Korea, Republic of)

    2016-04-15

    Vinyl boronic esters were synthesized from aryl alkynyl carboxylic acids and bis(pinacolato)diboron using a copper-catalyzed decarboxylative reaction. The reaction was conducted with CuI (10 mol %), bis-[2-(diphenylphosphino)phenyl]ether(20 mol %), and LiOMe (20 mol %) in DMSO at 50 .deg. C for 16 h. This method provided the desired vinyl boronic esters in good-to-moderate yields and showed good functional group tolerance.

  5. Silver-Catalyzed C(sp(3))-H Chlorination.

    Science.gov (United States)

    Ozawa, Jun; Kanai, Motomu

    2017-03-17

    A silver-catalyzed chlorination of benzylic, tertiary, and secondary C(sp(3))-H bonds was developed. The reaction proceeded with as low as 0.2 mol % catalyst loading at room temperature under air atmosphere with synthetically useful functional group compatibility. The regioselectivity and reactivity tendencies suggest that the chlorination proceeded through a radical pathway, but an intermediate alkylsilver species cannot be ruled out.

  6. Comparing Ru and Fe-catalyzed olefin metathesis.

    Science.gov (United States)

    Poater, Albert; Chaitanya Vummaleti, Sai Vikrama; Pump, Eva; Cavallo, Luigi

    2014-08-01

    Density functional theory calculations have been used to explore the potential of Fe-based complexes with an N-heterocyclic carbene ligand, as olefin metathesis catalysts. Apart from a less endothermic reaction energy profile, a small reduction in the predicted upper energy barriers (≈ 2 kcal mol(-1)) is calculated in the Fe catalyzed profile with respect to the Ru catalysed profile. Overall, this study indicates that Fe-based catalysts have the potential to be very effective olefin metathesis catalysts.

  7. Predictive Modeling of Metal-Catalyzed Polyolefin Processes

    OpenAIRE

    Khare, Neeraj Prasad

    2003-01-01

    This dissertation describes the essential modeling components and techniques for building comprehensive polymer process models for metal-catalyzed polyolefin processes. The significance of this work is that it presents a comprehensive approach to polymer process modeling applied to large-scale commercial processes. Most researchers focus only on polymerization mechanisms and reaction kinetics, and neglect physical properties and phase equilibrium. Both physical properties and phase equilib...

  8. Synthesis of heterocycles through transition-metal-catalyzed isomerization reactions.

    Science.gov (United States)

    Ishoey, Mette; Nielsen, Thomas E

    2014-07-14

    Metal-catalyzed isomerization of N- and O-allylic systems is emerging as an effective method to form synthetically useful iminium and oxocarbenium intermediates. In the presence of tethered nucleophiles, several recent examples illuminate this approach as a powerful strategy for the synthesis of structurally complex and diverse heterocycles. In this Concept article, we attempt to cover this area of research through a selection of recent versatile examples.

  9. Biodiesel by acid-catalyzed transesterification with butanol

    OpenAIRE

    Bynes, Adrian

    2012-01-01

    Jatropha oil and Rapeseed oil was transesterified with n-butanol by the use of H2SO4. Before conducting the experiments a review of the effect of alcohol type was preformed. Alcohols from methanol to butanol, branched and straight, were reviewed for the effect on the acid catalyzed transesterification reaction. From the review it was found that propanol and butanol were the best for the acidic transesterification reaction. Variables such as time, temperature, alcohol amount and catalyst c...

  10. Palladium-Catalyzed Synthesis of N-Aryl Carbamates

    Science.gov (United States)

    Vinogradova, Ekaterina V.; Park, Nathaniel H.; Fors, Brett P.; Buchwald, Stephen L.

    2013-01-01

    An efficient synthesis of aryl carbamates was achieved by introducing alcohols into the reaction of palladium-catalyzed cross-coupling of ArX (X = Cl, OTf) with sodium cyanate. The use of aryl triflates as electrophilic components in this transformation allowed for an expanded substrate scope for direct synthesis of aryl isocyanates. This methodology provides direct access to major carbamate protecting groups, S-thiocarbamates, and diisocyanate precursors to polyurethane materials. PMID:23441814

  11. Cobalt-catalyzed formation of symmetrical biaryls and its mechanism.

    Science.gov (United States)

    Moncomble, Aurélien; Le Floch, Pascal; Gosmini, Corinne

    2009-01-01

    Effective devotion: An efficient cobalt-catalyzed method devoted to the formation of symmetrical biaryls is described avoiding the preparation of organometallic reagents. Various aromatic halides functionalized by a variety of reactive group reagents are employed. Preliminary DFT calculations have shown that the involvement of a Co(I)/Co(III) couple is realistic at least in the case of 1,3-diazadienes as ligands (FG = functional group).

  12. Lactoperoxidase-catalyzed activation of carcinogenic aromatic and heterocyclic amines.

    Science.gov (United States)

    Gorlewska-Roberts, Katarzyna M; Teitel, Candee H; Lay, Jackson O; Roberts, Dean W; Kadlubar, Fred F

    2004-12-01

    Lactoperoxidase, an enzyme secreted from the human mammary gland, plays a host defensive role through antimicrobial activity. It has been implicated in mutagenic and carcinogenic activation in the human mammary gland. The potential role of heterocyclic and aromatic amines in the etiology of breast cancer led us to examination of the lactoperoxidase-catalyzed activation of the most commonly studied arylamine carcinogens: 2-amino-1-methyl-6-phenylimidazo[4,5-b]-pyridine (PhIP), benzidine, 4-aminobiphenyl (ABP), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx). In vitro activation was performed with lactoperoxidase (partially purified from bovine milk or human milk) in the presence of hydrogen peroxide and calf thymus DNA. Products formed during enzymatic activation were monitored by HPLC with ultraviolet and radiometric detection. Two of these products were characterized as hydrazo and azo derivatives by means of mass spectrometry. The DNA binding level of 3H- and 14C-radiolabeled amines after peroxidase-catalyzed activation was dependent on the hydrogen peroxide concentration, and the highest levels of carcinogen binding to DNA were observed at 100 microM H2O2. Carcinogen activation and the level of binding to DNA were in the order of benzidine > ABP > IQ > MeIQx > PhIP. One of the ABP adducts was identified, and the level at which it is formed was estimated to be six adducts/10(5) nucleotides. The susceptibility of aromatic and heterocyclic amines for lactoperoxidase-catalyzed activation and the binding levels of activated products to DNA suggest a potential role of lactoperoxidase-catalyzed activation of carcinogens in the etiology of breast cancer.

  13. Asymmetric Aldol Reaction Catalyzed by Modularly Designed Organocatalysts

    Institute of Scientific and Technical Information of China (English)

    Sinha, Debarshi; Mandal, Tanmay; Gogoi, Sanjib; Goldman, Joshua J.; 赵从贵

    2012-01-01

    The self-assembly of the precatalyst modules, which are amino acids and cinchona alkaloid derivatives, leads to the direct formation of the desired organocatalysts without any synthesis. These modularly designed organocatalysts (MDOs) may be used for catalyzed asymmetric aldol reaction the corresponding aldol products may be obtained in mediocre diastereoselectivities (up to 79 : 21 dr). Depending on structure of the aldehyde substrates, to excellent ee values (up to 92% ee) with moderate

  14. Asymmetric Stetter reactions catalyzed by thiamine diphosphate-dependent enzymes.

    Science.gov (United States)

    Kasparyan, Elena; Richter, Michael; Dresen, Carola; Walter, Lydia S; Fuchs, Georg; Leeper, Finian J; Wacker, Tobias; Andrade, Susana L A; Kolter, Geraldine; Pohl, Martina; Müller, Michael

    2014-12-01

    The intermolecular asymmetric Stetter reaction is an almost unexplored transformation for biocatalysts. Previously reported thiamine diphosphate (ThDP)-dependent PigD from Serratia marcescens is the first enzyme identified to catalyze the Stetter reaction of α,β-unsaturated ketones (Michael acceptor substrates) and α-keto acids. PigD is involved in the biosynthesis of the potent cytotoxic agent prodigiosin. Here, we describe the investigation of two new ThDP-dependent enzymes, SeAAS from Saccharopolyspora erythraea and HapD from Hahella chejuensis. Both show a high degree of homology to the amino acid sequence of PigD (39 and 51 %, respectively). The new enzymes were heterologously overproduced in Escherichia coli, and the yield of soluble protein was enhanced by co-expression of the chaperone genes groEL/ES. SeAAS and HapD catalyze intermolecular Stetter reactions in vitro with high enantioselectivity. The enzymes possess a characteristic substrate range with respect to Michael acceptor substrates. This provides support for a new type of ThDP-dependent enzymatic activity, which is abundant in various species and not restricted to prodigiosin biosynthesis in different strains. Moreover, PigD, SeAAS, and HapD are also able to catalyze asymmetric carbon-carbon bond formation reactions of aldehydes and α-keto acids, resulting in 2-hydroxy ketones.

  15. Anisotropic Morphological Changes in Goethite during Fe(2+)-Catalyzed Recrystallization.

    Science.gov (United States)

    Joshi, Prachi; Gorski, Christopher A

    2016-07-19

    When goethite is exposed to aqueous Fe(2+), rapid and extensive Fe atom exchange can occur between solid-phase Fe(3+) and aqueous Fe(2+) in a process referred to as Fe(2+)-catalyzed recrystallization. This process can lead to the structural incorporation or release of trace elements, which has important implications for contaminant remediation and nutrient biogeochemical cycling. Prior work found that the process did not cause major changes to the goethite structure or morphology. Here, we further investigated if and how goethite morphology and aggregation behavior changed temporally during Fe(2+)-catalyzed recrystallization. On the basis of existing literature, we hypothesized that Fe(2+)-catalyzed recrystallization of goethite would not result in changes to individual particle morphology or interparticle interactions. To test this, we reacted nanoparticulate goethite with aqueous Fe(2+) at pH 7.5 over 30 days and used transmission electron microscopy (TEM), cryogenic TEM, and (55)Fe as an isotope tracer to observe changes in particle dimensions, aggregation, and isotopic composition over time. Over the course of 30 days, the goethite particles substantially recrystallized, and the particle dimensions changed anisotropically, resulting in a preferential increase in the mean particle width. The temporal changes in goethite morphology could not be completely explained by a single mineral-transformation mechanism but rather indicated that multiple transformation mechanisms occurred concurrently. Collectively, these results demonstrate that the morphology of goethite nanoparticles does change during recrystallization, which is an important step toward identifying the driving force(s) of recrystallization.

  16. Enzyme-catalyzed biocathode in a photoelectrochemical biofuel cell

    Science.gov (United States)

    Yang, Jing; Hu, Donghua; Zhang, Xiaohuan; Wang, Kunqi; Wang, Bin; Sun, Bo; Qiu, Zhidong

    2014-12-01

    A novel double-enzyme photoelectrochemical biofuel cell (PEBFC) has been developed by taking glucose dehydrogenase (GDH) and horseradish peroxidase (HRP) as the enzyme of the photoanode and biocathode to catalyze the oxidation of glucose and the reduction of oxygen. A H2-mesoporphyrin IX is used as a dye for a TiO2 film electrode to fabricate a photoanode. The horseradish peroxidase (HRP) is immobilized on a glassy carbon (GC) electrode to construct a biocathode which is used to catalyze the reduction of oxygen in the PEBFC for the first time. The biocathode exhibits excellent electrocatalytic activity in the presence of O2. The performances of the PEBFC are obtained by current-voltage and power-voltage curves. The short-circuit current density (Isc), the open-circuit voltage (Voc), maximum power density (Pmax), fill factor (FF) and energy conversion efficiency (η) are 439 μA cm-2, 678 mV, 79 μW cm-2, 0.39 and 0.016%, respectively, and the incident photon-to-collected electron conversion efficiency (IPCE) is 32% at 350 nm. The Isc is higher than that of the PEBFC with Pt cathode, and the Voc is higher than that of the dye-sensitized solar cell or the enzyme-catalyzed biofuel cell operating individually, which demonstrates that the HRP is an efficient catalyst for the biocathode in the PEBFC.

  17. Aluminum-catalyzed silicon nanowires: Growth methods, properties, and applications

    Science.gov (United States)

    Hainey, Mel F.; Redwing, Joan M.

    2016-12-01

    Metal-mediated vapor-liquid-solid (VLS) growth is a promising approach for the fabrication of silicon nanowires, although residual metal incorporation into the nanowires during growth can adversely impact electronic properties particularly when metals such as gold and copper are utilized. Aluminum, which acts as a shallow acceptor in silicon, is therefore of significant interest for the growth of p-type silicon nanowires but has presented challenges due to its propensity for oxidation. This paper summarizes the key aspects of aluminum-catalyzed nanowire growth along with wire properties and device results. In the first section, aluminum-catalyzed nanowire growth is discussed with a specific emphasis on methods to mitigate aluminum oxide formation. Next, the influence of growth parameters such as growth temperature, precursor partial pressure, and hydrogen partial pressure on nanowire morphology is discussed, followed by a brief review of the growth of templated and patterned arrays of nanowires. Aluminum incorporation into the nanowires is then discussed in detail, including measurements of the aluminum concentration within wires using atom probe tomography and assessment of electrical properties by four point resistance measurements. Finally, the use of aluminum-catalyzed VLS growth for device fabrication is reviewed including results on single-wire radial p-n junction solar cells and planar solar cells fabricated with nanowire/nanopyramid texturing.

  18. Protection of wood from microorganisms by laccase-catalyzed iodination.

    Science.gov (United States)

    Schubert, M; Engel, J; Thöny-Meyer, L; Schwarze, F W M R; Ihssen, J

    2012-10-01

    In the present work, Norway spruce wood (Picea abies L.) was reacted with a commercial Trametes versicolor laccase in the presence of potassium iodide salt or the phenolic compounds thymol and isoeugenol to impart an antimicrobial property to the wood surface. In order to assess the efficacy of the wood treatment, a leaching of the iodinated and polymerized wood and two biotests including bacteria, a yeast, blue stain fungi, and wood decay fungi were performed. After laccase-catalyzed oxidation of the phenols, the antimicrobial effect was significantly reduced. In contrast, the enzymatic oxidation of iodide (I(-)) to iodine (I(2)) in the presence of wood led to an enhanced resistance of the wood surface against all microorganisms, even after exposure to leaching. The efficiency of the enzymatic wood iodination was comparable to that of a chemical wood preservative, VP 7/260a. The modification of the lignocellulose by the laccase-catalyzed iodination was assessed by the Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) technique. The intensities of the selected lignin-associated bands and carbohydrate reference bands were analyzed, and the results indicated a structural change in the lignin matrix. The results suggest that the laccase-catalyzed iodination of the wood surface presents an efficient and ecofriendly method for wood protection.

  19. Reduction of nitrobenzene by the catalyzed Fe/Cu process

    Institute of Scientific and Technical Information of China (English)

    XU Wenying; LI Ping; FAN Jinhong

    2008-01-01

    The polarization behavior of the couple Fe/Cu in 100 mg/L nitrobenzene aqueous solution was studied using Evans coupling diagrams. The results indicated that the iron corrosion was limited by both anodic and cathodic half-cell reactions under the neutral conditions and cathodically controlled under the alkaline conditions. Batch experiments were performed to study the effect of solution pH, reaction duration, concentration, type of electrolyte and dissolved oxygen (DO) on the reduction of nitrobenzene by the catalyzed Fe/Cu process. This process proved effective in the pH range of 3 to 11. The conversion efficiency of nitrobenzene at pH ≈ 10.1 was almost the same as that under highly acid conditions (pH ≈ 3). The degradation of nitrobenzene fell into two phases: adsorption and surface reduction, and the influence of adsorption and mass transfer became more extensive with solution concentration. The reduction rate decreased in the presence of DO in the solution, indicating that a need for aeration was eliminated in the catalyzed Fe/Cu process. Accordingly, spending on energy consumption would be reduced. Economic analysis indicated that merely 0.05 kg was required for the treatment of a ton of nitrobenzene-containing water with pH from 3 to 11. The catalyzed Fe/Cu process is cost-effective and of practical value.

  20. Acid-Catalyzed Preparation of Biodiesel from Waste Vegetable Oil: An Experiment for the Undergraduate Organic Chemistry Laboratory

    Science.gov (United States)

    Bladt, Don; Murray, Steve; Gitch, Brittany; Trout, Haylee; Liberko, Charles

    2011-01-01

    This undergraduate organic laboratory exercise involves the sulfuric acid-catalyzed conversion of waste vegetable oil into biodiesel. The acid-catalyzed method, although inherently slower than the base-catalyzed methods, does not suffer from the loss of product or the creation of emulsion producing soap that plagues the base-catalyzed methods when…

  1. Synthetic Study of Dragmacidin E: Construction of the Core Structure Using Pd-Catalyzed Cascade Cyclization and Rh-Catalyzed Aminoacetoxylation.

    Science.gov (United States)

    Inoue, Naoya; Nakano, Shun-Ichi; Harada, Shingo; Hamada, Yasumasa; Nemoto, Tetsuhiro

    2017-03-03

    We developed a novel synthetic method of the core structure of dragmacidin E bearing a 7-membered ring-fused bis(indolyl)pyrazinone skeleton. Formation of the 7-membered ring-fused tricyclic indole skeleton was accomplished using a palladium-catalyzed Heck insertion-allylic amination cascade. Vicinal difunctionalization of the 7-membered ring was realized via a rhodium-catalyzed aminoacetoxylation.

  2. Ammonia and hydrazine. Transition-metal-catalyzed hydroamination and metal-free catalyzed functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Bertrand, Guy [Univ. of California, San Diego, CA (United States)

    2012-06-29

    high temperatures and long reaction times. To address this issue, we have developed several new families of carbon- and boron-based ligands, which are even better donors. The corresponding metal complexes (particularly gold, rhodium, iridium, and ruthenium) of all these species will be tested in the Markovnikov and anti-Markovnikov hydroamination of alkynes, allenes, and also alkenes with ammonia and hydrazine. We will also develop metal-free catalytic processes for the functionalization of ammonia and hydrazine. By possessing both a lone pair of electrons and an accessible vacant orbital, singlet carbenes resemble and can mimic the chemical behavior of transition metals. Our preliminary results demonstrate that specially designed carbenes can split the N–H bond of ammonia by an initial nucleophilic activation that prevents the formation of Lewis acid-base adducts, which is the major hurdle for the transition metal catalyzed functionalization of NH3. The use of purely organic compounds as catalysts will eliminate the major drawbacks of transition-metal-catalysis technology, which are the excessive cost of metal complexes (metal + ligands) and in many cases the toxicity of the metal.

  3. Development and industrial application of catalyzer for low-temperature hydrogenation hydrolysis of Claus tail gas

    Directory of Open Access Journals (Sweden)

    Honggang Chang

    2015-10-01

    Full Text Available With the implementation of more strict national environmental protection laws, energy conservation, emission reduction and clean production will present higher requirements for sulfur recovery tail gas processing techniques and catalyzers. As for Claus tail gas, conventional hydrogenation catalyzers are gradually being replaced by low-temperature hydrogenation catalyzers. This paper concentrates on the development of technologies for low-temperature hydrogenation hydrolysis catalyzers, preparation of such catalyzers and their industrial application. In view of the specific features of SO2 hydrogenation and organic sulfur hydrolysis during low-temperature hydrogenation, a new technical process involving joint application of hydrogenation catalyzers and hydrolysis catalyzers was proposed. In addition, low-temperature hydrogenation catalyzers and low-temperature hydrolysis catalyzers suitable for low-temperature conditions were developed. Joint application of these two kinds of catalyzers may reduce the inlet temperatures in the conventional hydrogenation reactors from 280 °C to 220 °C, at the same time, hydrogenation conversion rates of SO2 can be enhanced to over 99%. To further accelerate the hydrolysis rate of organic sulfur, the catalyzers for hydrolysis of low-temperature organic sulfur were developed. In lab tests, the volume ratio of the total sulfur content in tail gas can be as low as 131 × 10−6 when these two kinds of catalyzers were used in a proportion of 5:5 in volumes. Industrial application of these catalyzers was implemented in 17 sulfur recovery tail gas processing facilities of 15 companies. As a result, Sinopec Jinling Petrochemical Company had outstanding application performances with a tail gas discharging rate lower than 77.9 mg/m3 and a total sulfur recovery of 99.97%.

  4. A SABATH Methyltransferase from the moss Physcomitrella patens catalyzes

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Nan [ORNL; Ferrer, Jean-Luc [Universite Joseph Fourier, France; Moon, Hong S [Department of Plant Sciences, University of Tennessee; Kapteyn, Jeremy [Institute of Biological Chemistry, Washington State University; Zhuang, Xiaofeng [Department of Plant Sciences, University of Tennessee; Hasebe, Mitsuyasu [Laboratory of Evolutionary Biology, National Institute for Biology, 38 Nishigounaka; Stewart, Neal C. [Department of Plant Sciences, University of Tennessee; Gang, David R. [Institute of Biological Chemistry, Washington State University; Chen, Feng [University of Tennessee, Knoxville (UTK)

    2012-01-01

    Known SABATH methyltransferases, all of which were identified from seed plants, catalyze methylation of either the carboxyl group of a variety of low molecular weight metabolites or the nitrogen moiety of precursors of caffeine. In this study, the SABATH family from the bryophyte Physcomitrella patens was identified and characterized. Four SABATH-like sequences (PpSABATH1, PpSABATH2, PpSABATH3, and PpSABATH4) were identified from the P. patens genome. Only PpSABATH1 and PpSABATH2 showed expression in the leafy gametophyte of P. patens. Full-length cDNAs of PpSABATH1 and PpSABATH2 were cloned and expressed in soluble form in Escherichia coli. Recombinant PpSABATH1 and PpSABATH2 were tested for methyltransferase activity with a total of 75 compounds. While showing no activity with carboxylic acids or nitrogen-containing compounds, PpSABATH1 displayed methyltransferase activity with a number of thiols. PpSABATH2 did not show activity with any of the compounds tested. Among the thiols analyzed, PpSABATH1 showed the highest level of activity with thiobenzoic acid with an apparent Km value of 95.5 lM, which is comparable to those of known SABATHs. Using thiobenzoic acid as substrate, GC MS analysis indicated that the methylation catalyzed by PpSABATH1 is on the sulfur atom. The mechanism for S-methylation of thiols catalyzed by PpSABATH1 was partially revealed by homology-based structural modeling. The expression of PpSABATH1 was induced by the treatment of thiobenzoic acid. Further transgenic studies showed that tobacco plants overexpressing PpSABATH1 exhibited enhanced tolerance to thiobenzoic acid, suggesting that PpSABATH1 have a role in the detoxification of xenobiotic thiols.

  5. Physio-pathological roles of transglutaminase-catalyzed reactions

    Institute of Scientific and Technical Information of China (English)

    Mariangela; Ricotta; Maura; Iannuzzi; Giulia; De; Vivo; Vittorio; Gentile

    2010-01-01

    Transglutaminases(TGs) are a large family of related and ubiquitous enzymes that catalyze post-translational modifications of proteins.The main activity of these enzymes is the cross-linking of a glutaminyl residue of a protein/peptide substrate to a lysyl residue of a protein/peptide co-substrate.In addition to lysyl residues,other second nucleophilic co-substrates may include monoamines or polyamines(to form mono-or bi-substituted/crosslinked adducts) or-OH groups(to form ester linkages) .In the absence of co-substrates,the nucleophile may be water,resulting in the net deamidation of the glutaminyl residue.The TG enzymes are also capable of catalyzing other reactions important for cell viability.The distribution and the physiological roles of TG enzymes have been widely studied in numerous cell types and tissues and their roles in several diseases have begun to be identified."Tissue" TG(TG2) ,a member of the TG family of enzymes,has definitely been shown to be involved in the molecular mechanisms responsible for a very widespread human pathology:i.e.celiac disease(CD) .TG activity has alsobeen hypothesized to be directly involved in the pathogenetic mechanisms responsible for several other human diseases,including neurodegenerative diseases,which are often associated with CD.Neurodegenerative diseases,such as Alzheimer’s disease,Parkinson’s disease,supranuclear palsy,Huntington’s disease and other recently identified polyglutamine diseases,are characterized,in part,by aberrant cerebral TG activity and by increased cross-linked proteins in affected brains.In this review,we discuss the physio-pathological role of TG-catalyzed reactions,with particular interest in the molecular mechanisms that could involve these enzymes in the physio-pathological processes responsible for human neurodegenerative diseases.

  6. Energy harvesting by implantable abiotically catalyzed glucose fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Kerzenmacher, S.; von Stetten, F. [Laboratory for MEMS Applications, Department of Microsystems Engineering (IMTEK), University of Freiburg, Georges-Koehler-Allee 106, D-79110 Freiburg (Germany); Ducree, J. [HSG-IMIT, Wilhelm-Schickard-Str. 10, D-78052 Villingen-Schwenningen (Germany); Zengerle, R. [Laboratory for MEMS Applications, Department of Microsystems Engineering (IMTEK), University of Freiburg, Georges-Koehler-Allee 106, D-79110 Freiburg (Germany); HSG-IMIT, Wilhelm-Schickard-Str. 10, D-78052 Villingen-Schwenningen (Germany)

    2008-07-15

    Implantable glucose fuel cells are a promising approach to realize an autonomous energy supply for medical implants that solely relies on the electrochemical reaction of oxygen and glucose. Key advantage over conventional batteries is the abundant availability of both reactants in body fluids, rendering the need for regular replacement or external recharging mechanisms obsolete. Implantable glucose fuel cells, based on abiotic catalysts such as noble metals and activated carbon, have already been developed as power supply for cardiac pacemakers in the late-1960s. Whereas, in vitro and preliminary in vivo studies demonstrated their long-term stability, the performance of these fuel cells is limited to the {mu}W-range. Consequently, no further developments have been reported since high-capacity lithium iodine batteries for cardiac pacemakers became available in the mid-1970s. In recent years research has been focused on enzymatically catalyzed glucose fuel cells. They offer higher power densities than their abiotically catalyzed counterparts, but the limited enzyme stability impedes long-term application. In this context, the trend towards increasingly energy-efficient low power MEMS (micro-electro-mechanical systems) implants has revived the interest in abiotic catalysts as a long-term stable alternative. This review covers the state-of-the-art in implantable abiotically catalyzed glucose fuel cells and their development since the 1960s. Different embodiment concepts are presented and the historical achievements of academic and industrial research groups are critically reviewed. Special regard is given to the applicability of the concept as sustainable micro-power generator for implantable devices. (author)

  7. On the Temperature Dependence of Enzyme-Catalyzed Rates.

    Science.gov (United States)

    Arcus, Vickery L; Prentice, Erica J; Hobbs, Joanne K; Mulholland, Adrian J; Van der Kamp, Marc W; Pudney, Christopher R; Parker, Emily J; Schipper, Louis A

    2016-03-29

    One of the critical variables that determine the rate of any reaction is temperature. For biological systems, the effects of temperature are convoluted with myriad (and often opposing) contributions from enzyme catalysis, protein stability, and temperature-dependent regulation, for example. We have coined the phrase "macromolecular rate theory (MMRT)" to describe the temperature dependence of enzyme-catalyzed rates independent of stability or regulatory processes. Central to MMRT is the observation that enzyme-catalyzed reactions occur with significant values of ΔCp(‡) that are in general negative. That is, the heat capacity (Cp) for the enzyme-substrate complex is generally larger than the Cp for the enzyme-transition state complex. Consistent with a classical description of enzyme catalysis, a negative value for ΔCp(‡) is the result of the enzyme binding relatively weakly to the substrate and very tightly to the transition state. This observation of negative ΔCp(‡) has important implications for the temperature dependence of enzyme-catalyzed rates. Here, we lay out the fundamentals of MMRT. We present a number of hypotheses that arise directly from MMRT including a theoretical justification for the large size of enzymes and the basis for their optimum temperatures. We rationalize the behavior of psychrophilic enzymes and describe a "psychrophilic trap" which places limits on the evolution of enzymes in low temperature environments. One of the defining characteristics of biology is catalysis of chemical reactions by enzymes, and enzymes drive much of metabolism. Therefore, we also expect to see characteristics of MMRT at the level of cells, whole organisms, and even ecosystems.

  8. Theoretical Study of the Effects of Di-Muonic Molecules on Muon-Catalyzed Fusion

    Science.gov (United States)

    2012-03-01

    MOLECULES ON MUON -CATALYZED FUSION DISSERTATION Eugene V. Sheely, Lieutenant Colonel, USA DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY...THEORETICAL STUDY OF THE EFFECTS OF DI-MUONIC MOLECULES ON MUON -CATALYZED FUSION DISSERTATION Presented to the Faculty...potential of enhancing the muon -catalyzed fusion reaction rate. In order to study these di-muonic molecules a method of non-adiabatic quantum mechanics

  9. Pd-catalyzed decarboxylative cross coupling of potassium polyfluorobenzoates with aryl bromides, chlorides, and triflates.

    Science.gov (United States)

    Shang, Rui; Xu, Qing; Jiang, Yuan-Ye; Wang, Yan; Liu, Lei

    2010-03-05

    Pd-catalyzed decarboxylative cross coupling of potassium polyfluorobenzoates with aryl bromides, chlorides, and triflates is achieved by using diglyme as the solvent. The reaction is useful for synthesis of polyfluorobiaryls from readily accessible and nonvolatile polyfluorobenzoate salts. Unlike the Cu-catalyzed decarboxylation cross coupling where oxidative addition is the rate-limiting step, in the Pd-catalyzed version decarboxylation is the rate-limiting step.

  10. Lipase-catalyzed enantioselective esterification of flurbiprofen with n-butanol

    OpenAIRE

    2000-01-01

    The influences of water activity and solvent hydrophobicity on the kinetics of the lipase-catalyzed enantioselective esterification of flurbiprofen with n-butanol were investigated. The solvent effect was not similar for lipases from Candida rugosa (Crl), Mucor javanicus (Mjl), and porcine pancreas (Ppl). The lipase-catalyzed reaction rates in different solvents across a wide range of water activities revealed that the Ppl-catalyzed reaction exhibited no enantioselectivity and no substantial ...

  11. Facile Rh(III)-Catalyzed Synthesis of Fluorinated Pyridines

    Science.gov (United States)

    Chen, Shuming; Bergman, Robert G.; Ellman, Jonathan A.

    2015-01-01

    A Rh(III)-catalyzed C–H functionalization approach was developed for the preparation of multi-substituted 3-fluoropyridines from α-fluoro-α,β-unsaturated oximes and alkynes. Oximes substituted with aryl, heteroaryl and alkyl β-substituents were effective coupling partners, as were symmetrical and unsymmetrical alkynes with aryl and alkyl substituents. The first examples of coupling α,β-unsaturated oximes with terminal alkynes was also demonstrated and proceeded with uniformly high regioselectivity to provide single 3-fluoropyridine regioisomers. Reactions were also conveniently set up in air on the bench top. PMID:25992591

  12. Rhodium(NHC)-catalyzed O-arylation of aryl bromides.

    Science.gov (United States)

    Kim, Hyun Jin; Kim, Min; Chang, Sukbok

    2011-05-06

    The first example of the rhodium-catalyzed O-arylation of aryl bromides is reported. While the right combination of rhodium species and N-heterocyclic carbene (NHC) offered an effective catalytic system enabling the arylation to proceed, the choice of NHC was determined to be most important. The developed O-arylation protocol has a wide range of substrate scope, high functional group tolerance, and flexibility allowing a complementary route to either N- or O-arylation depending on the choice of NHC.

  13. Triphenylphosphine-Catalyzed Michael Addition of Alcohols to Acrylic Compounds

    Institute of Scientific and Technical Information of China (English)

    LIU, Hai-Ling; JIANG, Huan-Feng; WANG, Yu-Gang

    2007-01-01

    A facile triphenylphosphine-catalyzed Michael addition of alcohols to acrylic compounds was described. The reaction was carried out in open air at refluxing temperature in the presence of 10 mol% PPh3. Michael addition of saturated and unsaturated alcohols to acrylonitrile or acrylates has been examined. The reaction gaveβ-alkoxy derivatives with isolated yields of 5%-79%. PPh3 is cheaper and more stable than those trialkylphosphines previously used for the similar reactions, and the products can be easily separated from the reaction mixture via distillation.

  14. Synthesis of Dihydrobenzofurans via Palladium-Catalyzed Heteroannulations

    Energy Technology Data Exchange (ETDEWEB)

    Roman Vladimirovich Rozhkov

    2004-12-19

    Palladium-catalyzed heteroannulation of 1,3-dienes with 3-iodo-2-alkenols, and 2-iodo-2-alkenols, as well as their amino analogs, affords the corresponding cyclic ethers and amines respectively. The presence of a {beta}-hydrogen in the vinylic halide results in {beta}-hydride elimination giving the corresponding alkyne. The presence of a bulky group in the {alpha}-position of the vinylic halide results in failure or reduced amounts of annulation products. A chloride source, pyridine base and electron-rich phosphine are essential for this reaction.

  15. FBH1 Catalyzes Regression of Stalled Replication Forks

    DEFF Research Database (Denmark)

    Fugger, Kasper; Mistrik, Martin; Neelsen, Kai J

    2015-01-01

    DNA replication fork perturbation is a major challenge to the maintenance of genome integrity. It has been suggested that processing of stalled forks might involve fork regression, in which the fork reverses and the two nascent DNA strands anneal. Here, we show that FBH1 catalyzes regression...... a model whereby FBH1 promotes early checkpoint signaling by remodeling of stalled DNA replication forks....... of a model replication fork in vitro and promotes fork regression in vivo in response to replication perturbation. Cells respond to fork stalling by activating checkpoint responses requiring signaling through stress-activated protein kinases. Importantly, we show that FBH1, through its helicase activity...

  16. Production of Chemoenzymatic Catalyzed Monoepoxide Biolubricant: Optimization and Physicochemical Characteristics

    OpenAIRE

    Jumat Salimon; Nadia Salih; Bashar Mudhaffar Abdullah

    2012-01-01

    Linoleic acid (LA) is converted to per-carboxylic acid catalyzed by an immobilized lipase from Candida antarctica (Novozym 435). This per-carboxylic acid is only intermediate and epoxidized itself in good yields and almost without consecutive reactions. Monoepoxide linoleic acid 9(12)-10(13)-monoepoxy 12(9)-octadecanoic acid (MEOA) was optimized using D-optimal design. At optimum conditions, higher yield% (82.14) and medium oxirane oxygen content (OOC) (4.91%) of MEOA were predicted at 15 μL ...

  17. Synthesis of Dihydrobenzofurans via Palladium-Catalyzed Heteroannulations

    Energy Technology Data Exchange (ETDEWEB)

    Rozhkov, Roman Vladimirovich [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    Palladium-catalyzed heteroannulation of 1,3-dienes with 3-iodo-2-alkenols, and 2-iodo-2-alkenols, as well as their amino analogs, affords the corresponding cyclic ethers and amines respectively. The presence of a β-hydrogen in the vinylic halide results in β-hydride elimination giving the corresponding alkyne. The presence of a bulky group in the α-position of the vinylic halide results in failure or reduced amounts of annulation products. A chloride source, pyridine base and electron-rich phosphine are essential for this reaction.

  18. Urea- and Thiourea-Catalyzed Aminolysis of Carbonates.

    Science.gov (United States)

    Blain, Marine; Yau, Honman; Jean-Gérard, Ludivine; Auvergne, Rémi; Benazet, Dominique; Schreiner, Peter R; Caillol, Sylvain; Andrioletti, Bruno

    2016-08-23

    The aminolysis of (poly)carbonates by (poly)amines provides access to non-isocyanate polyurethanes (NIPUs) that are toxic-reagent-free analogues of polyurethanes (PUs). Owing to their low reactivity, the ring opening of cyclic carbonates requires the use of a catalyst. Herein, we report that the more available and cheaper ureas could advantageously be used for catalyzing the formation of NIPUs at the expense of the thiourea analogues. In addition, we demonstrate a medium-range pKa of the (thio)urea and an unqeual substitution pattern is critical for controlling the efficiency of the carbonate opening.

  19. Synthesis of heterocycles through transition-metal-catalyzed isomerization reactions

    DEFF Research Database (Denmark)

    Ishøy, Mette; Nielsen, Thomas Eiland

    2014-01-01

    Metal-catalyzed isomerization of N- and O-allylic systems is emerging as an effective method to form synthetically useful iminium and oxocarbenium intermediates. In the presence of tethered nucleophiles, several recent examples illuminate this approach as a powerful strategy for the synthesis...... versatile method to form iminium and oxocarbenium ions. Given the number of reactions involving these highly electrophilic intermediates, this concept provides a sea of opportunities for heterocycle synthesis, (see scheme; Nu=nucleophile). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim....

  20. Lipase-catalyzed synthesis of monoacylglycerol in a homogeneous system.

    Science.gov (United States)

    Monteiro, Julieta B; Nascimento, Maria G; Ninow, Jorge L

    2003-04-01

    The 1,3-regiospecifique lipase, Lipozyme IM, catalyzed the esterification of lauric acid and glycerol in a homogeneous system. To overcome the drawback of the insolubility of glycerol in hexane, which is extensively used in enzymatic synthesis, a mixture of n-hexane/tert-butanol (1:1, v/v) was used leading to a monophasic system. The conversion of lauric acid into monolaurin was 65% in 8 h, when a molar ratio of glycerol to fatty acid (5:1) was used with the fatty acid at 0.1 M, and the phenomenon of acyl migration was minimized.

  1. Iodine - catalyzed prins cyclization of aliphatic and aromatic ketones

    Energy Technology Data Exchange (ETDEWEB)

    Kishore, K.R.; Reddy, K.; Silva Junior, Luiz F., E-mail: luizfsjr@iq.usp.br [Universidade de Sao Paulo (IQ/USP), SP (Brazil). Inst. de Quimica. Dept. de Quimica Fundamental

    2013-09-15

    Iodine-catalyzed Prins cyclization of homoallylic alcohols and ketones was investigated. Anhydrous conditions and inert atmosphere are not required in this metal-free protocol. The reaction of 2-(3,4-dihydronaphthalene-1-yl)propan-1-ol with six aliphatic symmetric ketones gave the desired products in 67-77% yield. Cyclization was performed with four aliphatic unsymmetric ketones, leading to corresponding pyrans in 66-76% yield. Prins cyclization was also accomplished with four aromatic ketones in 37-66% yield. Finally, Prins cyclization of the monoterpene isopulegol and acetone was successfully achieved. (author)

  2. Comparing Ru and Fe-catalyzed olefin metathesis

    KAUST Repository

    Poater, Albert

    2014-01-01

    Density functional theory calculations have been used to explore the potential of Fe-based complexes with an N-heterocyclic carbene ligand, as olefin metathesis catalysts. Apart from a less endothermic reaction energy profile, a small reduction in the predicted upper energy barriers (≈ 2 kcal mol -1) is calculated in the Fe catalyzed profile with respect to the Ru catalysed profile. Overall, this study indicates that Fe-based catalysts have the potential to be very effective olefin metathesis catalysts. This journal is © the Partner Organisations 2014.

  3. Catalyzing new product adoption at the base of the pyramid

    OpenAIRE

    Marinakis, Y.D.; Walsh, S. T.; Harms, R.

    2016-01-01

    One of the more perplexing of the entrepreneurial issues at the Base of the Pyramid (BoP) is how to catalyze new product adoption by BoP consumers. Because S-shaped adoption dynamics are the result of cultural transmission bias, the question can be rephrased as, how can an entrepreneur overcome conformity bias. We modified the Technology Acceptance Model (TAM) to include conformity bias. We then qualitatively applied the model to three examples from the literature, namely fuel stoves in Darfu...

  4. Deoxyribonucleoside kinases: two enzyme families catalyze the same reaction

    DEFF Research Database (Denmark)

    Sandrini, Michael; Piskur, Jure

    2005-01-01

    Mammals have four deoxyribonucleoside kinases, the cytoplasmic (TK1) and mitochondrial (TK2) thymidine kinases, and the deoxycytidine (dCK) and deoxyguanosine (dGK) kinases, which salvage the precursors for nucleic acids synthesis. In addition to the native deoxyribonucleoside substrates, the kin......, the kinases can phosphorylate and thereby activate a variety of anti-cancer and antiviral prodrugs. Recently, the crystal structure of human TK1 has been solved and has revealed that enzymes with fundamentally different origins and folds catalyze similar, crucial cellular reactions....

  5. Kinetics of acid-catalyzed cleavage of cumene hydroperoxide.

    Science.gov (United States)

    Levin, M E; Gonzales, N O; Zimmerman, L W; Yang, J

    2006-03-17

    The cleavage of cumene hydroperoxide, in the presence of sulfuric acid, to form phenol and acetone has been examined by adiabatic calorimetry. As expected, acid can catalyze cumene hydroperoxide reaction at temperatures below that of thermally-induced decomposition. At elevated acid concentrations, reactivity is also observed at or below room temperature. The exhibited reactivity behavior is complex and is significantly affected by the presence of other species (including the products). Several reaction models have been explored to explain the behavior and these are discussed.

  6. Rhodium catalyzed asymmetric Pauson-Khand reaction using SDP ligands

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The activity and enantiocontrol ability of the chiral catalysts prepared from spiro diphosphine ligands, SDP, and rhodium precursor were investigated in the asymmetric catalytic Pauson-Khand reaction. The results showed that SDP ligands were very effective in Rh-catalyzed Pauson-Khand reaction, and their complexes with rhodium could convert a variety of 1,6-enyne compounds into bicyclopentone derivatives under CO atmosphere in high yields with good enantioselectivities. The SbF6- was found to be a suitable counter anion of the catalyst, and 1,2-dichloroethane was the best choice of the solvent for Pauson-Khand reaction.

  7. Deoxyribonucleoside kinases: two enzyme families catalyze the same reaction

    DEFF Research Database (Denmark)

    Sandrini, Michael; Piskur, Jure

    2005-01-01

    Mammals have four deoxyribonucleoside kinases, the cytoplasmic (TK1) and mitochondrial (TK2) thymidine kinases, and the deoxycytidine (dCK) and deoxyguanosine (dGK) kinases, which salvage the precursors for nucleic acids synthesis. In addition to the native deoxyribonucleoside substrates, the kin......, the kinases can phosphorylate and thereby activate a variety of anti-cancer and antiviral prodrugs. Recently, the crystal structure of human TK1 has been solved and has revealed that enzymes with fundamentally different origins and folds catalyze similar, crucial cellular reactions....

  8. Optimization of Alkali Catalyzed Transesterification of Safflower Oil for Production of Biodiesel

    National Research Council Canada - National Science Library

    Math, M. C; Chandrashekhara, K. N

    2016-01-01

      The Central Composite Design is used for the optimization of alkaline catalyzed transesterification parameters such as methanol quantity, catalytic concentration, and rotational speed by keeping...

  9. Organizational innovation: a comprehensive model for catalyzing organizational development and change in a rapidly changing world

    National Research Council Canada - National Science Library

    Steiber, Annika; Alänge, Sverker

    2015-01-01

    ..., especially the processes through which organizational innovations are created, diffused, and sustained. There is thus a need for a more comprehensive understanding of mechanisms catalyzing organizational development...

  10. Fact Sheet: Nonylphenols and Nonylphenol Ethoxylates

    Science.gov (United States)

    EPA's existing chemicals programs address pollution prevention, risk assessment, hazard and exposure assessment and/or characterization, and risk management for chemicals substances in commercial use.

  11. Clariant Opens Ethoxylation Plant in China

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Switzerland-based specialty chemicals manufacturer Clariant International Ltd. has opened a regional headquarters in Singapore to serve customers in the Southeast Asia and Pacific regions. The location currently employs 200 people and also will serve as the regional headquarters for SOd-Chemie AG,

  12. Solution-solid-solid mechanism: superionic conductors catalyze nanowire growth.

    Science.gov (United States)

    Wang, Junli; Chen, Kangmin; Gong, Ming; Xu, Bin; Yang, Qing

    2013-09-11

    The catalytic mechanism offers an efficient tool to produce crystalline semiconductor nanowires, in which the choice, state, and structure of catalysts are active research issues of much interest. Here we report a novel solution-solid-solid (SSS) mechanism for nanowire growth catalyzed by solid-phase superionic conductor nanocrystals in low-temperature solution. The preparation of Ag2Se-catalyzed ZnSe nanowires at 100-210 °C is exampled to elucidate the SSS model, which can be extendable to grow other II-VI semiconductor (e.g., CdSe, ZnS, and CdS) nanowires by the catalysis of nanoscale superionic-phase silver or copper(I) chalcogenides (Ag2Se, Ag2S, and Cu2S). The exceptional catalytic ability of these superionic conductors originates from their structure characteristics, known for high-density vacancies and fast mobility of silver or copper(I) cations in the rigid sublattice of Se(2-) or S(2-) ions. Insights into the SSS mechanism are provided based on the formation of solid solution and the solid-state ion diffusion/transport at solid-solid interface between catalyst and nanowire.

  13. Thermodynamics of Enzyme-Catalyzed Reactions: Part 1. Oxidoreductases

    Science.gov (United States)

    Goldberg, Robert N.; Tewari, Yadu B.; Bell, Donna; Fazio, Kari; Anderson, Ellen

    1993-03-01

    Equilibrium constants and enthalpy changes for reactions catalyzed by oxidoreductases have been compiled. For each reaction the following information is given: the reference for the data; the reaction studied; the name of the enzyme used and its Enzyme Commission number; the method of measurement; the conditions of measurement (temperature, pH, ionic strength, and the buffer(s) and cofactor(s) used); the data and an evaluation of it; and, sometimes, commentary on the data and on any corrections which have been applied to it. The thermodynamic conventions pertinent to the tabulation of equilibrium data are discussed. A distinction is made between those thermodynamic quantities which pertain to the overall biochemical reaction and those which pertain to a reference reaction that involves specific species. The data from 205 references have been examined and evaluated. Chemical Abstract Service Registry Numbers have been assigned to the substances involved in these various reactions. There is a cross reference between the substances and the Enzyme Commission numbers of the enzymes used to catalyze the reactions in which the substances participated.

  14. Electrochemical reduction of oxygen catalyzed by Pseudomonas aeruginosa

    Energy Technology Data Exchange (ETDEWEB)

    Cournet, Amandine [Universite de Toulouse, UPS, LU49, Adhesion bacterienne et formation de biofilms, 35 chemin des Maraichers, 31062 Toulouse Cedex 09 (France)] [Laboratoire de Genie Chimique CNRS UMR5503, 4 allee Emile Monso, BP 84234, 31432 Toulouse Cedex 04 (France); Berge, Mathieu; Roques, Christine [Universite de Toulouse, UPS, LU49, Adhesion bacterienne et formation de biofilms, 35 chemin des Maraichers, 31062 Toulouse Cedex 09 (France); Bergel, Alain [Laboratoire de Genie Chimique CNRS UMR5503, 4 allee Emile Monso, BP 84234, 31432 Toulouse Cedex 04 (France); Delia, Marie-Line, E-mail: marieline.delia@ensiacet.f [Laboratoire de Genie Chimique CNRS UMR5503, 4 allee Emile Monso, BP 84234, 31432 Toulouse Cedex 04 (France)

    2010-07-01

    Pseudomonas aeruginosa has already been shown to catalyze oxidation processes in the anode compartment of a microbial fuel cell. The present study focuses on the reverse capacity of the bacterium, i.e. reduction catalysis. Here we show that P. aeruginosa is able to catalyze the electrochemical reduction of oxygen. The use of cyclic voltammetry showed that, for a given range of potential values, the current generated in the presence of bacteria could reach up to four times the current obtained without bacteria. The adhesion of bacteria to the working electrode was necessary for the catalysis to be observed but was not sufficient. The electron transfer between the working electrode and the bacteria did not involve mediator metabolites like phenazines. The transfer was by direct contact. The catalysis required a certain contact duration between electrodes and live bacteria but after this delay, the metabolic activity of cells was no longer necessary. Membrane-bound proteins, like catalase, may be involved. Various strains of P. aeruginosa, including clinical isolates, were tested and all of them, even catalase-defective mutants, presented the same catalytic property. P. aeruginosa offers a new model for the analysis of reduction catalysis and the protocol designed here may provide a basis for developing an interesting tool in the field of bacterial adhesion.

  15. Ozonation of Indigo Carmine Catalyzed with Fe-Pillared Clay

    Directory of Open Access Journals (Sweden)

    Miriam Bernal

    2013-01-01

    Full Text Available The ozonation catalyzed by iron-pillared clays was studied. The degradation of dye indigo carmine (IC was elected as test reaction. Fe-pillared clays were synthesized by employing hydrolyzed FeCl3 solutions and bentonite. The pillared structure was verified by XRD and by XPS the oxidation state of iron in the synthesized material was established to be +2. By atomic absorption the weight percentage of iron was determined to be 16. The reaction was conducted in a laboratory scale up-flow bubble column reactor. From the studied variables the best results were obtained with a particle size of 60 microns, pH=3, ozone flow of 0.045 L/min, and catalyst concentration of 100 mg/L. IC was completely degraded and degradation rate was found to be double when using Fe-PILCS than with ozone alone. DQO reduction was also significantly higher with catalyzed than with noncatalyzed ozonation.

  16. Lipase-catalyzed polyester synthesis--a green polymer chemistry.

    Science.gov (United States)

    Kobayashi, Shiro

    2010-01-01

    This article is a short comprehensive review describing in vitro polyester synthesis catalyzed by a hydrolysis enzyme of lipase, most of which has been developed for these two decades. Polyesters are prepared by repeated ester bond-formation reactions; they include two major modes, ring-opening polymerization (ROP) of cyclic monomers such as cyclic esters (lactones) and condensation polymerization via the reaction between a carboxylic acid or its ester group and an alcohol group. Polyester synthesis is, therefore, a reaction in reverse way of in vivo lipase catalysis of ester bond-cleavage with hydrolysis. The lipase-catalyzed polymerizations show very high chemo-, regio-, and enantio-selectivities and involve various advantageous characteristics. Lipase is robust and compatible with other chemical catalysts, which allows novel chemoenzymatic processes. New syntheses of a variety of functional polyesters and a plausible reaction mechanism of lipase catalysis are mentioned. The polymerization characteristics are of green nature currently demanded for sustainable society, and hence, desirable for conducting 'green polymer chemistry'.

  17. Catalyzed Synthesis of Zinc Clays by Prebiotic Central Metabolites.

    Science.gov (United States)

    Zhou, Ruixin; Basu, Kaustuv; Hartman, Hyman; Matocha, Christopher J; Sears, S Kelly; Vali, Hojatollah; Guzman, Marcelo I

    2017-04-03

    How primordial metabolic networks such as the reverse tricarboxylic acid (rTCA) cycle and clay mineral catalysts coevolved remains a mystery in the puzzle to understand the origin of life. While prebiotic reactions from the rTCA cycle were accomplished via photochemistry on semiconductor minerals, the synthesis of clays was demonstrated at low temperature and ambient pressure catalyzed by oxalate. Herein, the crystallization of clay minerals is catalyzed by succinate, an example of a photoproduced intermediate from central metabolism. The experiments connect the synthesis of sauconite, a model for clay minerals, to prebiotic photochemistry. We report the temperature, pH, and concentration dependence on succinate for the synthesis of sauconite identifying new mechanisms of clay formation in surface environments of rocky planets. The work demonstrates that seeding induces nucleation at low temperatures accelerating the crystallization process. Cryogenic and conventional transmission electron microscopies, X-ray diffraction, diffuse reflectance Fourier transformed infrared spectroscopy, and measurements of total surface area are used to build a three-dimensional representation of the clay. These results suggest the coevolution of clay minerals and early metabolites in our planet could have been facilitated by sunlight photochemistry, which played a significant role in the complex interplay between rocks and life over geological time.

  18. Acid-Catalyzed Hydration of anti-Sesquinorbornene.

    Science.gov (United States)

    Slebocka-Tilk, H.; Brown, R. S.

    1996-11-15

    The acid-catalyzed hydration of anti-sesquinorbornene (1) has been studied at 25 degrees C in 20% DME/H(2)O from 0.001 M kinetic isotope effect for hydration of 1 is 2.7, and a plot of the observed second-order rate constant for the hydration in a mixed solvent system of H(2)O/D(2)O against the atom fraction of deuterium (n) is bowed upward. The reaction also shows marked buffer catalysis by formic, chloroacetic, and dichloroacetic acids, the Brønsted alpha being 1 for these three carboxylic acids: H(3)O(+) does not fit on this Brønsted line. A mechanism for the reaction is presented which is consistent with the generally accepted one for acid-catalyzed hydration of an alkene in which the rate-limiting step involves proton transfer from H(3)O(+) to the double bond. Whether attack of a second water on the developing carbocation occurs simultaneously with protonation cannot be ascertained from the data for 1, but if so, the extent of its C-OH(2) bond formation must be small enough that there is little change in the bonding of these O-H bonds.

  19. Acid base catalyzed transesterification kinetics of waste cooking oil

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Siddharth; Sharma, M.P.; Rajvanshi, Shalini [Alternate Hydro Energy Centre, Indian Institute of Technology, Roorkee (India)

    2011-01-15

    The present study reports the results of kinetics study of acid base catalyzed two step transesterification process of waste cooking oil, carried out at pre-determined optimum temperature of 65 C and 50 C for esterification and transesterification process respectively under the optimum condition of methanol to oil ratio of 3:7 (v/v), catalyst concentration 1%(w/w) for H{sub 2}SO{sub 4} and NaOH and 400 rpm of stirring. The optimum temperature was determined based on the yield of ME at different temperature. Simply, the optimum concentration of H{sub 2}SO{sub 4} and NaOH was determined with respect to ME Yield. The results indicated that both esterification and transesterification reaction are of first order rate reaction with reaction rate constant of 0.0031 min{sup -1} and 0.0078 min{sup -1} respectively showing that the former is a slower process than the later. The maximum yield of 21.50% of ME during esterification and 90.6% from transesterification of pretreated WCO has been obtained. This is the first study of its kind which deals with simplified kinetics of two step acid-base catalyzed transesterification process carried under the above optimum conditions and took about 6 h for complete conversion of TG to ME with least amount of activation energy. Also various parameters related to experiments are optimized with respect to ME yield. (author)

  20. Study of microwave effects on the lipase-catalyzed hydrolysis.

    Science.gov (United States)

    Chen, Chia-Chen; Reddy, P Muralidhar; Devi, C Shobha; Chang, Po-Chi; Ho, Yen-Peng

    2016-01-01

    The effect of microwave heating on lipase-catalyzed reaction remains controversial. It is not clear whether the reaction rate enhancements are purely due to thermal/heating effects or to non-thermal effects. Therefore, quantitative mass spectrometry was used to conduct accurate kinetic analysis of lipase-catalyzed hydrolysis of triolein by microwave and conventional heating. Commercial lipases from Candida rugosa (CRL), Porcine Pancreas (PPL), and Burkholderia cepacia (BCL) were used. Hydrolysis reactions were performed at various temperatures and pH levels, along with various amounts of buffer and enzymes. Hydrolysis product yields at each time point using an internal-standard method showed no significant difference between microwave and conventional heating conditions when the reaction was carried out at the same temperature. CRL showed optimum catalytic activity at 37 °C, while PPL and BCL had better activities at 50 °C. The phosphate buffer was found to give a better hydrolysis yield than the Tris-HCl buffer. Overall results prove that a non-thermal effect does not exist in microwave-assisted lipase hydrolysis of triolein. Therefore, conventional heating at high temperatures (e.g., 50 °C) can be also used to accelerate hydrolysis reactions.

  1. Lipase-catalyzed polyester synthesis – A green polymer chemistry

    Science.gov (United States)

    Kobayashi, Shiro

    2010-01-01

    This article is a short comprehensive review describing in vitro polyester synthesis catalyzed by a hydrolysis enzyme of lipase, most of which has been developed for these two decades. Polyesters are prepared by repeated ester bond-formation reactions; they include two major modes, ring-opening polymerization (ROP) of cyclic monomers such as cyclic esters (lactones) and condensation polymerization via the reaction between a carboxylic acid or its ester group and an alcohol group. Polyester synthesis is, therefore, a reaction in reverse way of in vivo lipase catalysis of ester bond-cleavage with hydrolysis. The lipase-catalyzed polymerizations show very high chemo-, regio-, and enantio-selectivities and involve various advantageous characteristics. Lipase is robust and compatible with other chemical catalysts, which allows novel chemo-enzymatic processes. New syntheses of a variety of functional polyesters and a plausible reaction mechanism of lipase catalysis are mentioned. The polymerization characteristics are of green nature currently demanded for sustainable society, and hence, desirable for conducting ‘green polymer chemistry’. PMID:20431260

  2. Metalloporphyrin solubility: a trigger for catalyzing reductive dechlorination of tetrachloroethylene.

    Science.gov (United States)

    Dror, Ishai; Schlautman, Mark A

    2004-02-01

    Metalloporphyrins are well known for their electron-transfer roles in many natural redox systems. In addition, several metalloporphyrins and related tetrapyrrole macrocycles complexed with various core metals have been shown to catalyze the reductive dechlorination of certain organic compounds, thus demonstrating the potential for using naturally occurring metalloporphyrins to attenuate toxic and persistent chlorinated organic pollutants in the environment. However, despite the great interest in reductive dechlorination reactions and the wide variety of natural and synthetic porphyrins currently available, only soluble porphyrins, which comprise a small fraction of this particular family of organic macrocycles, have been used as electron-transfer shuttles in these reactions. Results from the present study clearly demonstrate that metalloporphyrin solubility is a key factor in their ability to catalyze the reductive dechlorination of tetrachloroethylene and its daughter compounds. Additionally, we show that certain insoluble and nonreactive metalloporphyrins can be activated as catalysts merely by changing solution conditions to bring about their dissolution. Furthermore, once a metalloporphyrin is fully dissolved and activated, tetrachloroethylene transformation proceeds rapidly, giving nonchlorinated and less toxic alkenes as the major reaction products. Results from the present study suggest that if the right environmental conditions exist or can be created, specific metalloporphyrins may provide a solution for cleaning up sites that are contaminated with chlorinated organic pollutants.

  3. IRC analysis of methanol carbonylation reaction catalyzed by rhodium complex

    Institute of Scientific and Technical Information of China (English)

    HAO Maorong; FENG Wenlin; JI Yongqiang; LEI Ming

    2004-01-01

    In the reaction cycle for methanol carbonylation catalyzed by Rh complex, the structure geometries of the reactant, intermediates, transition states and product of each elemental reaction have been studied by using the energy gradient method at HF/LANL2DZ level, and the changes of their potential profiles have also been calculated. Through IRC analyses of the transition states for each elemental reaction, it is confirmed that the various structure geometries obtained are stationary points on the cycle reaction pathway of methanol carbonylation catalyzed by Rh complex, and the changes are given in energies and structure geometries of the reactant molecules along the reaction pathway of lowest energy. It has been proposed that the geometrical conversions of intermediates play an important role during the cycle reaction. Through analyses of structure geometries, it has been suggested that, in addition to cis- and trans- structure exchange linkage of catalysis reactive species, the two pathways, cis- and trans-cata- lyzed cycle reactions, can also be linked through geometrical conversion of intermediates, of which the activation energy is 49.79 kJ/mol. Moreover, the reductive elimination elemental reaction may be neither cis-cycle nor trans- one, showing that the cycle reaction can be achieved through various pathways. However different the pathway, the oxidative addition elemental reaction of CH3I is the rate-controlling step.

  4. Enzyme catalyzed electricity-driven water softening system.

    Science.gov (United States)

    Arugula, Mary A; Brastad, Kristen S; Minteer, Shelley D; He, Zhen

    2012-12-10

    Hardness in water, which is caused by divalent cations such as calcium and magnesium ions, presents a major water quality problem. Because hard water must be softened before use in residential applications, there is great interest in the saltless water softening process because, unlike ion exchange softeners, it does not introduce additional ions into water. In this study, a saltless hardness removal driven by bioelectrochemical energy produced through enzymatic oxidation of glucose was proposed and investigated. Glucose dehydrogenase was coated on a carbon electrode to catalyze glucose oxidation in the presence of NAD⁺ as a cofactor/mediator and methylene green as an electrocatalyst. The results showed that electricity generation stimulated hardness removal compared with non-electricity conditions. The enzymatic water softener worked upon a 6h batch operation per day for eight days, and achieved an average hardness removal of 46% at a high initial concentration of 800 mg/L as CaCO₃. More hardness was removed at a lower initial concentration. For instance, at 200mg/L as CaCO₃ the enzymatic water softener removed 76.4±4.6% of total hardness. The presence of magnesium ions decreased hardness removal because of its larger hydrated radius than calcium ions. The enzymatic water softener removed 70-80% of total hardness from three actual hard water samples. These results demonstrated a proof-of-concept that enzyme catalyzed electricity generation can be used to soften hard water.

  5. Cu-Catalyzed Click Reaction in Carbohydrate Chemistry.

    Science.gov (United States)

    Tiwari, Vinod K; Mishra, Bhuwan B; Mishra, Kunj B; Mishra, Nidhi; Singh, Anoop S; Chen, Xi

    2016-03-09

    Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC), popularly known as the "click reaction", serves as the most potent and highly dependable tool for facile construction of simple to complex architectures at the molecular level. Click-knitted threads of two exclusively different molecular entities have created some really interesting structures for more than 15 years with a broad spectrum of applicability, including in the fascinating fields of synthetic chemistry, medicinal science, biochemistry, pharmacology, material science, and catalysis. The unique properties of the carbohydrate moiety and the advantages of highly chemo- and regioselective click chemistry, such as mild reaction conditions, efficient performance with a wide range of solvents, and compatibility with different functionalities, together produce miraculous neoglycoconjugates and neoglycopolymers with various synthetic, biological, and pharmaceutical applications. In this review we highlight the successful advancement of Cu(I)-catalyzed click chemistry in glycoscience and its applications as well as future scope in different streams of applied sciences.

  6. Immobilization of Chiral Ferrocenyl Ligands on Silica Gel and their Testing in Pd-catalyzed Allylic Substitution and Rh-catalyzed Hydrogenation

    Directory of Open Access Journals (Sweden)

    Duncan J. Macquarrie

    2005-07-01

    Full Text Available Five different silica gels containing two chiral ferrocenyl ligands were prepared by various synthetic routes and tested in an enantioselective Pd(0-catalyzed allylic substitution and Rh-catalyzed hydrogenation. All the prepared anchored ligands were characterized by porosimetry data, DRIFTS spectra, thermal data and AAS. The aim of the work was to compare the influence of the carrier, surface properties and immobilization strategy on the performance of the catalyst.

  7. ROLE OF COPPER,ZINC-SUPEROXIDE DISMUTASE IN CATALYZING NITROTYROSINE FORMATION IN MURINE LIVER

    Science.gov (United States)

    The solely known function of Cu,Zn-superoxide dismutase (SOD1) is to catalyze the dismutation of superoxide anion into hydrogen peroxide. Our objective was to determine if SOD1 catalyzed murine liver protein nitration induced by acetaminophen (APAP) and lipopolysaccharide (LPS). Liver and plasma ...

  8. Copper-catalyzed cascade reactions of α,β-unsaturated esters with keto esters

    OpenAIRE

    Zhengning Li; Chongnian Wang; Zengchang Li

    2015-01-01

    A copper-catalyzed cascade reaction of α,β-unsaturated esters with keto esters is reported. It features a copper-catalyzed reductive aldolization followed by a lactonization. This method provides a facile approach to prepare γ-carboxymethyl-γ-lactones and δ-carboxymethyl-δ-lactones under mild reaction conditions.

  9. Kinetic study on the acid-catalyzed hydrolysis of cellulose to levulinic acid

    NARCIS (Netherlands)

    Girisuta, B.; Janssen, L. P. B. M.; Heeres, H. J.

    2007-01-01

    A variety of interesting bulk chemicals is accessible by the acid-catalyzed hydrolysis of cellulose. An interesting example is levulinic acid, a versatile precursor for fuel additives, polymers, and resins. A detailed kinetic study on the acid-catalyzed hydrolysis of cellulose to levulinic acid is

  10. Copper-catalyzed aerobic oxidative synthesis of aryl nitriles from benzylic alcohols and aqueous ammonia.

    Science.gov (United States)

    Tao, Chuanzhou; Liu, Feng; Zhu, Youmin; Liu, Weiwei; Cao, Zhiling

    2013-05-28

    Copper-catalyzed direct conversion of benzylic alcohols to aryl nitriles was realized using NH3(aq.) as the nitrogen source, O2 as the oxidant and TEMPO as the co-catalyst. Furthermore, copper-catalyzed one-pot synthesis of primary aryl amides from alcohols was also achieved.

  11. Oxygenase-Catalyzed Desymmetrization of N,N-Dialkyl-piperidine-4-carboxylic Acids**

    Science.gov (United States)

    Rydzik, Anna M; Leung, Ivanhoe K H; Kochan, Grazyna T; McDonough, Michael A; Claridge, Timothy D W; Schofield, Christopher J

    2014-01-01

    γ-Butyrobetaine hydroxylase (BBOX) is a 2-oxoglutarate dependent oxygenase that catalyzes the final hydroxylation step in the biosynthesis of carnitine. BBOX was shown to catalyze the oxidative desymmetrization of achiral N,N-dialkyl piperidine-4-carboxylates to give products with two or three stereogenic centers. PMID:25164544

  12. Aminoacyl-coenzyme A synthesis catalyzed by a CoA ligase from Penicillium chrysogenum

    NARCIS (Netherlands)

    Koetsier, Martijn J.; Jekel, Peter A.; Wijma, Hein J.; Bovenberg, Roel A. L.; Janssen, Dick B.

    2011-01-01

    Coenzyme A ligases play an important role in metabolism by catalyzing the activation of carboxylic acids. In this study we describe the synthesis of aminoacyl-coenzyme As (CoAs) catalyzed by a CoA ligase from Penicillium chrysogenum. The enzyme accepted medium-chain length fatty acids as the best

  13. LIPASE-CATALYZED TRANSESTERIFICATION OF PALM KERNEL OIL WITH DIALKYLCARBONATES

    Directory of Open Access Journals (Sweden)

    Tjahjono Herawan

    2014-01-01

    Full Text Available Lipase-catalyzed transesterifications-especially in a solvent-free medium-are important for industrial applications because such systems would have an enormous advantage by avoiding the problem of separation, toxicity and flammability of organic solvents. However, the organic solvent-free alcoholysis, especially methanolysis, does not give high conversions. The same problem also occurs when ethyl or methyl acetate are used as acyl acceptors. The main problems of lipase-catalyzed organic solvent-free alcoholysis are first, the solubility of the plant oil in the substrate or solvent and second, the fact that transesterification is an equilibrium reaction. Dialkyl carbonates, versatile compounds due to their chemical reactivity and physical properties, may provide an alternative to solve both problems. Using dialkyl carbonates transesterification is not an equilibrium reaction, because the intermediate compound immediately decomposes to carbon dioxide and an alcohol. Moreover, dialkyl carbonates (especially dimethyl carbonate are cheap and widely available. For single step lipase-catalyzed transesterification of palm kernel oil, diakyl carbonates (in this case dimethyl and diethyl carbonate gave better yields compared to those of short chain alcohols. The rate of ester formation with dialkyl carbonates as substrate was about 6-7 times higher than that obtained with short chain alcohols. The formation of esters was gradually increased by a higher enzyme amount from 5-20% (w/w of oil for 8 h reaction time. However from the economic point of view, an enzyme amount of 10% on the weight base of oil was proposed for further reaction. Generally, the highest ester formation was observed when a temperature of 60°C was used. However, in the case of dimethyl carbonate little difference was observed at reaction temperatures of 60 and 70oC and the reactions proceeded nearly identically. The esters formation increased drastically up to more than 70% when water

  14. Degradation and transformation of atrazine under catalyzed ozonation process with TiO2 as catalyst.

    Science.gov (United States)

    Yang, Yixin; Cao, Hongbin; Peng, Pai; Bo, Hongmiao

    2014-08-30

    Degradation of atrazine by heterogeneously catalyzed ozonation was carried out with TiO2 in the form of rutile as the catalyst. Some experimental factors such as catalyst dose, ozone dose and initial concentration of atrazine were investigated for their influence on catalyzed ozonation process. Although atrazine was effectively removed from aqueous solution by catalyzed ozonation process, the mineralization degree only reached 56% at the experimental conditions. Five transformation products were identified by GC/MS analysis. The degradation of atrazine involved de-alkylation, de-chlorination and de-amination. Diaminotriazine and 5-azauracil were the de-chlorinated and de-aminated products, respectively. The evolution of concentration of transformation products during catalyzed ozonation process was compared with uncatalyzed ozonation to show the degradation pathway. Toxicity tests based on the inhibition of the luminescence emitted by Vibrio fisheri indicated the detoxification of atrazine by catalyzed ozonation.

  15. CRYSTAL DEFECTS IN PLASMA NITRIDED LAYER CATALYZED BY RARE EARTH

    Institute of Scientific and Technical Information of China (English)

    F.S. Chen; Y.X. Liu; D.K. Liang; L.M. Xiao

    2002-01-01

    The microstructure of plasma nitrided layer catalyzed by rare-earth elements has beenstudied with TEM. The results show that the grains of γ'-Fe4N phase are refinedby rare-earth elements and the plane defects in boundary are increased by rare-earthelements. The addition of rare-earth element increases the bombardment effect andthe number of crystal defects such as vacancies, dislocation loops, twins and stackingfaults in γ'-Fe4N phase and can produce the high-density dislocations in the ferrite ofdiffusion layer at a distance 0. 08mm from the surface. The production of a numberof crystal defects is one of important reasons why rare-earth element accelerates thediffusion of nitrogen atoms during plasma-nitridiug.

  16. Rh(II)-catalyzed Reactions of Diazoesters with Organozinc Reagents

    Science.gov (United States)

    Panish, Robert; Selvaraj, Ramajeyam; Fox, Joseph M.

    2015-01-01

    Rh(II)-catalyzed reactions of diazoesters with organozinc reagents are described. Diorganozinc reagents participate in reactions with diazo compounds by two distinct, catalyst-dependent mechanisms. With bulky diisopropylethylacetate ligands, the reaction mechanism is proposed to involve initial formation of a Rh-carbene and subsequent carbozincation to give a zinc enolate. With Rh2(OAc)4, it is proposed that initial formation of an azine precedes 1,2-addition by an organozinc reagent. This straightforward route to the hydrazone products provides a useful method for preparing chiral quaternary α-aminoesters or pyrazoles via the Paul-Knorr condensation with 1,3-diketones. Crossover and deuterium labeling experiments provide evidence for the mechanisms proposed. PMID:26241081

  17. Towards a methanol economy: Zeolite catalyzed production of synthetic fuels

    DEFF Research Database (Denmark)

    Mentzel, Uffe Vie

    chapter is a literature study of Mobil’s “methanol to hydrocarbons” (MTH) process, giving an overview of the history of the process, the nature of the employed catalysts, and the reaction mechanism. In the third chapter, a series of experiments concerning co conversion of ethane and methanol over......, the conversion capacities for all four alcohols are markedly lower than for H-ZSM-5, and H Beta has higher conversion capacity for methanol than the other alcohols. Furthermore, conventional and mesoporous H Ga MFI was employed in the conversion of methanol and 2 propanol. These catalysts showed a lower...... selectivity towards aromatics than H-ZSM-5 and the mesoporous H-Ga-MFI deactivated extremely slowly during the conversion of 2-propanol and only very small amounts of coke were deposited on the gallium based zeolites compared to H-ZSM-5. In the fifth chapter the direct zeolite catalyzed production...

  18. WILDCAT: a catalyzed D-D tokamak reactor

    Energy Technology Data Exchange (ETDEWEB)

    Evans, K. Jr.; Baker, C.C.; Brooks, J.N.

    1981-11-01

    WILDCAT is a conceptual design of a catalyzed D-D, tokamak, commercial, fusion reactor. WILDCAT utilizes the beneficial features of no tritium breeding, while not extrapolating unnecessarily from existing D-T designs. The reactor is larger and has higher magnetic fields and plasma pressures than typical D-T devices. It is more costly, but eliminates problems associated with tritium breeding and has tritium inventories and throughputs approximately two orders of magnitude less than typical D-T reactors. There are both a steady-state version with Alfven-wave current drive and a pulsed version. Extensive comparison with D-T devices has been made, and cost and safety analyses have been included. All of the major reactor systems have been worked out to a level of detail appropriate to a complete, conceptual design.

  19. FBH1 Catalyzes Regression of Stalled Replication Forks

    Directory of Open Access Journals (Sweden)

    Kasper Fugger

    2015-03-01

    Full Text Available DNA replication fork perturbation is a major challenge to the maintenance of genome integrity. It has been suggested that processing of stalled forks might involve fork regression, in which the fork reverses and the two nascent DNA strands anneal. Here, we show that FBH1 catalyzes regression of a model replication fork in vitro and promotes fork regression in vivo in response to replication perturbation. Cells respond to fork stalling by activating checkpoint responses requiring signaling through stress-activated protein kinases. Importantly, we show that FBH1, through its helicase activity, is required for early phosphorylation of ATM substrates such as CHK2 and CtIP as well as hyperphosphorylation of RPA. These phosphorylations occur prior to apparent DNA double-strand break formation. Furthermore, FBH1-dependent signaling promotes checkpoint control and preserves genome integrity. We propose a model whereby FBH1 promotes early checkpoint signaling by remodeling of stalled DNA replication forks.

  20. Lactam hydrolysis catalyzed by mononuclear metallo-ß-bactamases

    DEFF Research Database (Denmark)

    Olsen, Lars; Antony, J; Ryde, U

    2003-01-01

    . For most studied systems, the tetrahedral structure is a stable intermediate. Moreover, the C-N bond in the lactam ring is intact in this intermediate, as well as in the following transition state-its cleavage is induced by proton transfer to the nitrogen atom in the lactam ring. However, for the model...... with Asp as a proton shuttle, attack of the zinc-bond hydroxide ion seems to be concerted with the proton transfer. We have also studied the effect of replacing one of the histidine ligands by an asparagine or glutamine residue, giving a zinc site representative of other subclasses of metallo......Two central steps in the hydrolysis of lactam antibiotics catalyzed by mononuclear metallo-beta-lactamases, formation of the tetrahedral intermediate and its breakdown by proton transfer, are studied for model systems using the density functional B3LYP method. Metallo-beta-lactamases have two metal...

  1. Recent developments in lipase-catalyzed synthesis of polyesters.

    Science.gov (United States)

    Kobayashi, Shiro

    2009-02-18

    Polyester synthesis by lipase catalyst involves two major polymerization modes: i) ring-opening polymerization of lactones, and, ii) polycondensation. Ring-opening polymerization includes the finding of lipase catalyst; scope of reactions; polymerization mechanism; ring-opening polymerization reactivity of lactones; enantio-, chemo- and regio-selective polymerizations; and, chemoenzymatic polymerizations. Polycondensation includes polymerizations involving condensation reactions between carboxylic acid and alcohol functional groups to form an ester bond. In most cases, a carboxylic acid group is activated as an ester form, such as a vinyl ester. Many recently developed polymerizations demonstrate lipase catalysis specific to enzymatic polymerization and appear very useful. Also, since lipase-catalyzed polyester synthesis provides a good opportunity for conducting "green polymer chemistry", the importance of this is described.

  2. Muon Catalyzed Fusion in 3 K Solid Deuterium

    CERN Document Server

    Knowles, P E; Bailey, J M; Beer, G A; Beveridge, J L; Fujiwara, M C; Huber, T M; Jacot-Guillarmod, R; Kammel, P; Kim, S K; Kunselman, A R; Marshall, G M; Martoff, C J; Mason, G R; Mulhauser, F; Olin, A; Petitjean, C; Porcelli, T A; Zmeskal, J; Zmeskal, and J.

    1997-01-01

    Muon catalyzed fusion in deuterium has traditionally been studied in gaseous and liquid targets. The TRIUMF solid-hydrogen-layer target system has been used to study the fusion reaction rates in the solid phase of D_2 at a target temperature of 3 K. Products of two distinct branches of the reaction were observed; neutrons by a liquid organic scintillator, and protons by a silicon detector located inside the target system. The effective molecular formation rate from the upper hyperfine state of $\\mu d$ and the hyperfine transition rate have been measured: $\\tilde{\\lambda}_(3/2)=2.71(7)_{stat.}(32)_{syst.} The molecular formation rate is consistent with other recent measurements, but not with the theory for isolated molecules. The discrepancy may be due to incomplete thermalization, an effect which was investigated by Monte Carlo calculations. Information on branching ratio parameters for the s and p wave d+d nuclear interaction has been extracted.

  3. Calcium-catalyzed pyrolysis of lignocellulosic biomass components.

    Science.gov (United States)

    Case, Paige A; Truong, Chi; Wheeler, M Clayton; DeSisto, William J

    2015-09-01

    The present study examines the effect of calcium pretreatment on pyrolysis of individual lignocellulosic compounds. Previous work has demonstrated that the incorporation of calcium compounds with the feedstock prior to pyrolysis has a significant effect on the oxygen content and stability of the resulting oil. The aim of this work was to further explore the chemistry of calcium-catalyzed pyrolysis. Bench-scale pyrolysis of biomass constituents, including lignin, cellulose and xylan is performed and compared to the oils produced from pyrolysis of the same components after calcium pretreatment. The resulting oils were analyzed by quantitative GC-MS and SEC. These analyses, together with data collected from previous work provide evidence which was used to develop proposed reaction pathways for pyrolysis of calcium-pretreatment biomass. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Synthesis of Rosin Acid Starch Catalyzed by Lipase

    Directory of Open Access Journals (Sweden)

    Rihui Lin

    2014-01-01

    Full Text Available Rosin, an abundant raw material from pine trees, was used as a starting material directly for the synthesis of rosin acid starch. The esterification reaction was catalyzed by lipase (Novozym 435 under mild conditions. Based on single factor experimentation, the optimal esterification conditions were obtained as follows: rosin acid/anhydrous glucose unit in the molar ratio 2 : 1, reaction time 4 h at 45°C, and 15% of lipase dosage. The degree of substitution (DS reaches 0.098. Product from esterification of cassava starch with rosin acid was confirmed by FTIR spectroscopy and iodine coloration analysis. Scanning electron microscopy and X-ray diffraction analysis showed that the morphology and crystallinity of the cassava starch were largely destroyed. Thermogravimetric analysis indicated that thermal stability of rosin acid starch decreased compared with native starch.

  5. Silica nanospheres formation induced by peroxidase-catalyzed phenol polymerization

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    To examine whether lignin-like compound is correlated with silica precipitation in grass, a series of simulated chemical experiments were carried out at ambient temperature and pressure, close to cell wall pH, with phenol polymerization catalyzed by peroxidase in silicon solution. The experiments showed that phenol polymer (a kind of lignin-like substance) caused silica nanosphere precipitation similar to those caused by protein in diatom cell wall previously reported by other authors. The sphere diameter varied with different kinds of phenol and the concentrations of phenol and silicon. Silicon precipitation had phenol and silicon saturation effect, meaning that when the concentration ratio of soluble silicon to phenol exceeded a certain value, the amount of silicon precipitation would decrease.

  6. Chemical and genomic evolution of enzyme-catalyzed reaction networks.

    Science.gov (United States)

    Kanehisa, Minoru

    2013-09-02

    There is a tendency that a unit of enzyme genes in an operon-like structure in the prokaryotic genome encodes enzymes that catalyze a series of consecutive reactions in a metabolic pathway. Our recent analysis shows that this and other genomic units correspond to chemical units reflecting chemical logic of organic reactions. From all known metabolic pathways in the KEGG database we identified chemical units, called reaction modules, as the conserved sequences of chemical structure transformation patterns of small molecules. The extracted patterns suggest co-evolution of genomic units and chemical units. While the core of the metabolic network may have evolved with mechanisms involving individual enzymes and reactions, its extension may have been driven by modular units of enzymes and reactions.

  7. Chemo- and Enantioselective Intramolecular Silver-Catalyzed Aziridinations.

    Science.gov (United States)

    Ju, Minsoo; Weatherly, Cale D; Guzei, Ilia A; Schomaker, Jennifer M

    2017-08-07

    Asymmetric nitrene-transfer reactions are a powerful tool for the preparation of enantioenriched amine building blocks. Reported herein are chemo- and enantioselective silver-catalyzed aminations which transform di- and trisubstituted homoallylic carbamates into [4.1.0]-carbamate-tethered aziridines in good yields and with ee values of up to 92 %. The effects of the substrate, silver counteranion, ligand, solvent, and temperature on both the chemoselectivity and ee value were explored. Stereochemical models were proposed to rationalize the observed absolute stereochemistry of the aziridines, which undergo nucleophilic ring opening to yield enantioenriched amines with no erosion in stereochemical integrity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Mg-catalyzed autoclave synthesis of aligned silicon carbide nanostructures.

    Science.gov (United States)

    Xi, Guangcheng; Liu, Yankuan; Liu, Xiaoyan; Wang, Xiaoqing; Qian, Yitai

    2006-07-27

    In this article, a novel magnesium-catalyzed co-reduction route was developed for the large-scale synthesis of aligned beta-SiC one-dimensional (1D) nanostructures at relative lower temperature (600 degrees C). By carefully controlling the reagent concentrations, we could synthesize beta-SiC rodlike and needlelike nanostructures. The possible growth mechanism of the as-synthesized beta-SiC 1D nanostructures has been investigated. The structure and morphology of the as-synthesized beta-SiC nanostructures are characterized using X-ray diffraction, Fourier transform infrared absorption, and scanning and transmission electron microscopes. Raman and photoluminescence properties are also investigated at room temperature. The as-synthesized beta-SiC nanostructures exhibit strong shape-dependent field emission properties. Corresponding to their shapes, the as-synthesized nanorods and nanoneedles display the turn-on fields of 12, 8.4, and 1.8 V/microm, respectively.

  9. Metal-catalyzed protein tyrosine nitration in biological systems.

    Science.gov (United States)

    Campolo, Nicolás; Bartesaghi, Silvina; Radi, Rafael

    2014-11-01

    Protein tyrosine nitration is an oxidative postranslational modification that can affect protein structure and function. It is mediated in vivo by the production of nitric oxide-derived reactive nitrogen species (RNS), including peroxynitrite (ONOO(-)) and nitrogen dioxide ((•)NO₂). Redox-active transition metals such as iron (Fe), copper (Cu), and manganese (Mn) can actively participate in the processes of tyrosine nitration in biological systems, as they catalyze the production of both reactive oxygen species and RNS, enhance nitration yields and provide site-specificity to this process. Early after the discovery that protein tyrosine nitration can occur under biologically relevant conditions, it was shown that some low molecular weight transition-metal centers and metalloproteins could promote peroxynitrite-dependent nitration. Later studies showed that nitration could be achieved by peroxynitrite-independent routes as well, depending on the transition metal-catalyzed oxidation of nitrite (NO₂(-)) to (•)NO₂ in the presence of hydrogen peroxide. Processes like these can be achieved either by hemeperoxidase-dependent reactions or by ferrous and cuprous ions through Fenton-type chemistry. Besides the in vitro evidence, there are now several in vivo studies that support the close relationship between transition metal levels and protein tyrosine nitration. So, the contribution of transition metals to the levels of tyrosine nitrated proteins observed under basal conditions and, specially, in disease states related with high levels of these metal ions, seems to be quite clear. Altogether, current evidence unambiguously supports a central role of transition metals in determining the extent and selectivity of protein tyrosine nitration mediated both by peroxynitrite-dependent and independent mechanisms.

  10. Cyclic peptide formation catalyzed by an antibody ligase

    Science.gov (United States)

    Smithrud, David B.; Benkovic, Patricia A.; Benkovic, Stephen J.; Roberts, Victoria; Liu, Josephine; Neagu, Irina; Iwama, Seiji; Phillips, Barton W.; Smith, Amos B.; Hirschmann, Ralph

    2000-01-01

    Cyclic hexapeptides represent a class of compounds with important, diverse biological activities. We report herein that the antibody 16G3 catalyzes the cyclization of d-Trp-Gly-Pal-Pro-Gly-Phe⋅p-nitrophenyl ester (8a) to give c-(d-Trp-Gly-Pal-Pro-Gly-l-Phe) (11a). The antibody does not, however, catalyze either epimerization or hydrolysis. The resulting rate enhancement of the cyclization by 16G3 (22-fold) was sufficient to form the desired product in greater than 90% yield. In absolute rate terms, the turnover of 16G3 is estimated to be 2 min−1. The background rate of epimerization of 8a was reduced from 10 to 1% and hydrolysis from 50 to 4% in the presence of 16G3. As expected, the catalytic effects of 16G3 were blocked by the addition of an amount of the hapten equal to twice the antibody concentration. We also synthesized three diastereomers of 8a: the d-Trp1-d-Phe6 (8b), l-Trp1-l-Phe6 (8c), and l-Trp1-d-Phe6 (8d) hexapeptides as well as d-Trp′-l-Trp6 (12) and d-Phe′-l-Phe6 (13). As expected, the rate enhancement by 16G3 was greatest for 8a, because the stereochemistry of Trp1 and Phe6 matches that of the corresponding residues on the hapten used to induce the biosynthesis of 16G3. A model of the variable domain of 16G3 was generated from the primary sequence using the antibody structural database to guide the model construction. The resulting model provided support for some previously proposed interpretations of the kinetic data, while providing valuable new insights for others. PMID:10688882

  11. The general base in the thymidylate synthase catalyzed proton abstraction.

    Science.gov (United States)

    Ghosh, Ananda K; Islam, Zahidul; Krueger, Jonathan; Abeysinghe, Thelma; Kohen, Amnon

    2015-12-14

    The enzyme thymidylate synthase (TSase), an important chemotherapeutic drug target, catalyzes the formation of 2'-deoxythymidine-5'-monophosphate (dTMP), a precursor of one of the DNA building blocks. TSase catalyzes a multi-step mechanism that includes the abstraction of a proton from the C5 of the substrate 2'-deoxyuridine-5'-monophosphate (dUMP). Previous studies on ecTSase proposed that an active-site residue, Y94 serves the role of the general base abstracting this proton. However, since Y94 is neither very basic, nor connected to basic residues, nor located close enough to the pyrimidine proton to be abstracted, the actual identity of this base remains enigmatic. Based on crystal structures, an alternative hypothesis is that the nearest potential proton-acceptor of C5 of dUMP is a water molecule that is part of a hydrogen bond (H-bond) network comprised of several water molecules and several protein residues including H147, E58, N177, and Y94. Here, we examine the role of the residue Y94 in the proton abstraction step by removing its hydroxyl group (Y94F mutant). We investigated the effect of the mutation on the temperature dependence of intrinsic kinetic isotope effects (KIEs) and found that these KIEs are more temperature dependent than those of the wild-type enzyme (WT). These results suggest that the phenolic -OH of Y94 is a component of the transition state for the proton abstraction step. The findings further support the hypothesis that no single functional group is the general base, but a network of bases and hydroxyls (from water molecules and tyrosine) sharing H-bonds across the active site can serve the role of the general base to remove the pyrimidine proton.

  12. 鹰嘴豆中3种异黄酮及其乙氧基化衍生物体外协同降糖活性研究*%Study on Synergistic Hypoglycemic ActivityIn Vitroof Three Kinds of Isoflavone in Chickpea and Its Derivatives of Ethoxylation

    Institute of Scientific and Technical Information of China (English)

    李朋收; 魏颖; 时晓娟; 李博; 王东超; 徐暾海; 刘铜华

    2015-01-01

    目的:通过对鹰嘴豆中3种异黄酮类化合物染料木素、鹰嘴豆芽素A、刺芒柄花素进行乙氧基化结构修饰,研究其降糖活性及协同降糖活性。方法:对上述3种异黄酮类化合物进行乙氧基化结构修饰,并研究该3种异黄酮类化合物及其衍生物降糖活性,并对化合物进行组合给药,研究其之间存在的协同降糖活性,选择胰岛素抵抗HepG2细胞作为降糖活性筛选模型。结果:获得4个乙氧基化产物,3个母体异黄酮衍生物中染料木素的降糖活性优于鹰嘴豆芽素A和刺芒柄花素,差异具有统计学意义(P0.05),化合物b和c降糖效果均不如化合物a和d,差异具有统计学意义(P0.05)。结论:本研究发现,通过化合物组合,化合物之间可以起到协同作用,发挥更好的降糖效果,为开发具有自主知识产权的降糖药物提供一定的基础。%Through the ethoxylation structure modification of three isoflavones which were genistein, biochanin A and formononetin in chickpea, the hypoglycemic activity and the synergistic hypoglycemic activity were studied. Ethoxylation structure modification was given on three kinds of isoflavones. The hypoglycemic activity of three kinds of isoflavones and their derivatives were studied. The synergistic hypoglycemic activity of the compounds was also studied. The insulin-resistance HepG2 cell was selected as the model of hypoglycemic activity screening. The results showed that four ethoxylation products were synthesized. And the hypoglycemic activity of genistein was better than biochanin A and formononetin with significant difference (P 0.05). Effects of the compound b and compound c were not as good as the compound a and compound d. There was statistical difference (P 0.05). It was concluded that the combinations of compounds played synergistic effects with better hypoglycemic effect. It provided a basis for developing hypoglycemic agents with

  13. 考虑反应热的乙氧基化反应精馏塔能量内部集成与优化%Energy internal integration and optimization within ethoxylation reactive distillation column with consideration of heat of reaction

    Institute of Scientific and Technical Information of China (English)

    安维中; 孟霞; 李宏熙; 周立明; 朱建民

    2012-01-01

    以正丁醇和环氧乙烷为原料合成乙二醇正丁醚(EGMBE)为例,利用数学模型和模拟分析方法,研究了包含大量反应热效应的乙氧基化反应精馏(ERD)塔中反应热的利用及系统能量优化问题.研究表明,当采用常规的、将反应段直接叠加于提馏段之上的塔设计时,反应热并没有贡献于分离操作或减小再沸器的热负荷,而只是被冷凝器中的冷却介质移走.分析了反应热的可利用途径,提出一种将反应段和提馏段分割、从反应段移出反应热供提馏段加热的内部热集成乙氧基化反应精馏结构——IHIERD.模拟结果表明,IHIERD将使再沸器的温度从462.5 K降低到420.0K,冷凝器负荷降低11%,外部能量输入降低14%,节能效果显著.%The utilization of heat of reaction and energy optimization within ethoxylation reactive distillation (ERD) column, which involves reactions with highly thermal effect, was studied by using the mathematical model and simulation method. A typical ethoxylation system, the synthesis of ethylene glycol monobutyl ether (EGMBE) from ethylene oxide (EO) and n-butanol was employed as example. Firstly, the conventional column design, into which a reactive section was superimposed onto a stripping section, was used as a base case for analysis, and detailed simulations were carried out to investigate the influence of heat of reaction on the process performance. The results obtained showed that, by the adoption of the conventional design of ERD column, the heat of reaction was finally removed from condenser by cooling medium, I. E. , the heat of reaction could not be directly utilized in ERD column for improving the separation operation or reducing the heat duty of reboiler. Based on this, the approaches to utilizing heat of reaction was analyzed, and an internally heat-integrated ethoxylation reactive distillation structure, IHIERD, was proposed to maximize the energy efficiency of system, into which the

  14. Lipase catalyzed ester synthesis for food processing industries

    Directory of Open Access Journals (Sweden)

    Aravindan Rajendran

    2009-02-01

    Full Text Available Lipases are one of the most important industrial biocatalyst which catalyzes the hydrolysis of lipids. It can also reverse the reaction at minimum water activity. Because of this pliable nature, it is widely exploited to catalyze the diverse bioconversion reactions, such as hydrolysis, esterification, interesterification, alcoholysis, acidolysis and aminolysis. The property to synthesize the esters from the fatty acids and glycerol promotes its use in various ester synthesis. The esters synthesized by lipase finds applications in numerous fields such as biodiesel production, resolution of the recemic drugs, fat and lipid modification, flavour synthesis, synthesis of enantiopure pharmaceuticals and nutraceuticals. It plays a crucial role in the food processing industries since the process is unaffected by the unwanted side products. Lipase modifications such as the surfactant coating, molecular imprinting to suit for the non-aqueous ester synthesis have also been reported. This review deals with lipase catalyzed ester synthesis, esterification strategies, optimum conditions and their applications in food processing industries.Lipases são catalizadores industriais dos mais importantes, os quais catalizam a hidrólise de lipídeos. Também podem reverter a reação a um mínimo de atividade de água. Devido sua natureza flexível, é amplamente explorada para catalizar uma diversidade de reações de bioconversão como hidrólise, esterificação, interesterificação, alcoólise, acidólise e aminólise. A propriedade de síntese de esteres a partir de ácidos graxos e glicerol promoveu seu uso em várias sínteses de esteres. Os esteres sintetizados por lipases encontram aplicação em numerosos campos como a produção de biodiesel, resolução de drogas racêmicas, modificação de gorduras e lipídios, sintese de aromas, síntese de produtos farmacêuticos enantiopuro e nutracêuticos. As lipases possuem um papel crucial nas indústrias de

  15. Recent advances in osmium-catalyzed hydrogenation and dehydrogenation reactions.

    Science.gov (United States)

    Chelucci, Giorgio; Baldino, Salvatore; Baratta, Walter

    2015-02-17

    CONSPECTUS: A current issue in metal-catalyzed reactions is the search for highly efficient transition-metal complexes affording high productivity and selectivity in a variety of processes. Moreover, there is also a great interest in multitasking catalysts that are able to efficiently promote different organic transformations by careful switching of the reaction parameters, such as temperature, solvent, and cocatalyst. In this context, osmium complexes have shown the ability to catalyze efficiently different types of reactions involving hydrogen, proving at the same time high thermal stability and simple synthesis. In the catalytic reduction of C═X (X = O, N) bonds by both hydrogenation (HY) and transfer hydrogenation (TH) reactions, the most interest has been focused on homogeneous systems based on rhodium, iridium, and in particular ruthenium catalysts, which have proved to catalyze chemo- and stereoselective hydrogenations with remarkable efficiency. By contrast, osmium catalysts have received much less attention because they are considered less active on account of their slower ligand exchange kinetics. Thus, this area remained almost neglected until recent studies refuted these prejudices. The aim of this Account is to highlight the impressive developments achieved over the past few years by our and other groups on the design of new classes of osmium complexes and their applications in homogeneous catalytic reactions involving the hydrogenation of carbon-oxygen and carbon-nitrogen bonds by both HY and TH reactions as well as in alcohol deydrogenation (DHY) reactions. The work described in this Account demonstrates that osmium complexes are emerging as powerful catalysts for asymmetric and non-asymmetric syntheses, showing a remarkably high catalytic activity in HY and TH reactions of ketones, aldehydes, imines, and esters as well in DHY reactions of alcohols. Thus, for instance, the introduction of ligands with an NH function, possibly in combination with a

  16. High power density yeast catalyzed microbial fuel cells

    Science.gov (United States)

    Ganguli, Rahul

    Microbial fuel cells leverage whole cell biocatalysis to convert the energy stored in energy-rich renewable biomolecules such as sugar, directly to electrical energy at high efficiencies. Advantages of the process include ambient temperature operation, operation in natural streams such as wastewater without the need to clean electrodes, minimal balance-of-plant requirements compared to conventional fuel cells, and environmentally friendly operation. These make the technology very attractive as portable power sources and waste-to-energy converters. The principal problem facing the technology is the low power densities compared to other conventional portable power sources such as batteries and traditional fuel cells. In this work we examined the yeast catalyzed microbial fuel cell and developed methods to increase the power density from such fuel cells. A combination of cyclic voltammetry and optical absorption measurements were used to establish significant adsorption of electron mediators by the microbes. Mediator adsorption was demonstrated to be an important limitation in achieving high power densities in yeast-catalyzed microbial fuel cells. Specifically, the power densities are low for the length of time mediator adsorption continues to occur. Once the mediator adsorption stops, the power densities increase. Rotating disk chronoamperometry was used to extract reaction rate information, and a simple kinetic expression was developed for the current observed in the anodic half-cell. Since the rate expression showed that the current was directly related to microbe concentration close to the electrode, methods to increase cell mass attached to the anode was investigated. Electrically biased electrodes were demonstrated to develop biofilm-like layers of the Baker's yeast with a high concentration of cells directly connected to the electrode. The increased cell mass did increase the power density 2 times compared to a non biofilm fuel cell, but the power density

  17. Construction of cyclic enones via gold-catalyzed oxygen transfer reactions

    Directory of Open Access Journals (Sweden)

    Gerald B. Hammond

    2011-05-01

    Full Text Available During the last decade, gold-catalyzed reactions have become a tour de force in organic synthesis. Recently, the gold-, Brønsted acid- or Lewis acid-catalyzed oxygen transfer from carbonyl to carbon–carbon triple bond, the so-called alkyne–carbonyl metathesis, has attracted much attention because this atom economical transformation generates α,β-unsaturated carbonyl derivatives which are of great interest in synthetic organic chemistry. This mini-review focuses on the most recent achievements on gold-catalyzed oxygen transfer reactions of tethered alkynones, diynes or alkynyl epoxides to cyclic enones. The corresponding mechanisms for the transformations are also discussed.

  18. DFT Study of the Molybdenum-Catalyzed Deoxydehydration of Vicinal Diols

    DEFF Research Database (Denmark)

    Lupp, Daniel; Christensen, Niels Johan; Dethlefsen, Johannes Rytter

    2015-01-01

    The mechanism of the molybdenum-catalyzed deoxydehydration (DODH) of vicinal diols has been investigated using density functional theory. The proposed catalytic cycle involves condensation of the diol with an MoVI oxo complex, oxidative cleavage of the diol resulting in an MoIV complex......, and extrusion of the alkene. We have compared the proposed pathway with several alternatives, and the results have been corroborated by comparison with the molybdenum- catalyzed sulfoxide reduction recently published by Sanz et al. and with experimental observations for the DODH itself. Improved understanding...... of the mechanism should expedite future optimization of molybdenum-catalyzed biomass transformations....

  19. Isotopic study of ceria-catalyzed soot oxidation in the presence of NOx

    OpenAIRE

    Guillén Hurtado, Noelia; García García, Avelina; Bueno López, Agustín

    2013-01-01

    The ceria-catalyzed soot oxidation mechanism has been studied by a pulse technique with labeled O2 in the absence and presence of NO, using ceria–soot mixtures prepared in the loose contact mode. In the absence of soot, the ceria-catalyzed oxidation of NO to NO2 takes place with ceria oxygen and not with gas-phase O2. However, the oxygen exchange process between gas-phase O2 and ceria oxygen (to yield back O2, but with oxygen atoms coming from ceria) prevailed with regard to the ceria-catalyz...

  20. Exploring chain length selectivity in HIC-catalyzed polycondensation reactions.

    Science.gov (United States)

    Feder, David; Gross, Richard A

    2010-03-08

    Polyester synthesis activity of immobilized Humicola insolens (HiC) was systematically studied with three-series of substrates varying in (i) omega-hydroxyalkanoic acid (omegaHA), (ii) alpha,omega-n-alkane diol, and (iii) alpha,omega-n-alkane diacid chain length. Covalent immobilization of HiC on Amberzyme oxirane (AO) resin (i.e., AO-HiC) was prepared. HiC-AO's activity for omegaHA substrates with 6, 10, 12, and 16 carbons was C16 > C12, where C10-omegaHA and C6-omegaHA were not polymerized. In contrast, N435's activity for omegaHA substrates was C16 = C12 > C10, where C6-omegaHA was not polymerized. HiC-AO activity for copolymerization of sebacic acid (C10-diacid) with alpha,omega-n-alkane diols with 3-, 4-, 5-, 6-, and 8-carbon chain lengths was C8 > C6, where C3, C4, and C5 diols were not polymerized. N435's relative activity for diol substrates was C8 = C6 = C5 > C4 > C3. HiC-AO activity for copolymerizations of 1,8-octanediol with alpha,omega-n-alkane diacids with 6-, 8-, 9-, 10-, and 13-carbon chain lengths was C13 = C10, where HiC showed little activity for C6, C8, and C9 diacid copolymerization. N435 displayed similar activity for all these diacid chain lengths. Thus, N435 has a broader substrate promiscuity than HiC-AO. This is most apparent for shorter chain length omegaHA, diol, and diacid monomers. These trends were similarly observed for a series of small molecule esterification reactions. Comparison of HiC-AO- and N435-catalyzed C16-HA homopolymerization at 8 h gave polymers with M(n) 40.4 and 25.5 kg/mol, respectively. Furthermore, HiC-AO- and N435-catalyzed copolymerization of 1,8-octanediol/C13-diacid polymerizations at 8 h gave polymers with M(n) of 11.0 and 9.6 kg/mol, respectively.

  1. Enzyme-Catalyzed Regioselective Modification of Starch Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Soma [Polytechnic Univ., Brooklyn, NY (United States). National Science Foundation (NSF) Center for Biocatalysis and Bioprocessing of Macromolecules, Othmer Dept. of Chemical and Biological Science and Engineering; Sahoo, Bishwabhusan [Polytechnic Univ., Brooklyn, NY (United States). National Science Foundation (NSF) Center for Biocatalysis and Bioprocessing of Macromolecules, Othmer Dept. of Chemical and Biological Science and Engineering; Teraoka, Iwao [Polytechnic Univ., Brooklyn, NY (United States). National Science Foundation (NSF) Center for Biocatalysis and Bioprocessing of Macromolecules, Othmer Dept. of Chemical and Biological Science and Engineering; Miller, Lisa M. [Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source (NSLS); Gross, Richard A. [Polytechnic Univ., Brooklyn, NY (United States). National Science Foundation (NSF) Center for Biocatalysis and Bioprocessing of Macromolecules, Othmer Dept. of Chemical and Biological Science and Engineering

    2004-12-13

    The selective esterification of starch nanoparticles was performed using as catalyst Candida antartica Lipase B (CAL-B) in its immobilized (Novozym 435) and free (SP-525) forms. The starch nanoparticles were made accessible for acylation reactions by formation of Aerosol-OT (AOT, bis(2-ethylhexyl)sodium sulfosuccinate) stabilized microemulsions. Starch nanoparticles in microemulsions were reacted with vinyl stearate, ε-caprolactone, and maleic anhydride at 40 °C for 48 h to give starch esters with degrees of substitution (DS) of 0.8, 0.6, and 0.4, respectively. Substitution occurred regioselectively at the C-6 position of the glucose repeat units. Infrared microspectroscopy (IRMS) revealed that AOT-coated starch nanoparticles diffuse into the outer 50 μm shell of catalyst beads. Thus, even though CAL-B is immobilized within a macroporous resin, CAL-B is sufficiently accessible to the starch nanoparticles. When free CAL-B was incorporated along with starch within AOT-coated reversed micelles, CAL-B was also active and catalyzed the acylation with vinyl stearate (24 h, 40 °C) to give DS = 0.5. After removal of surfactant from the modified starch nanoparticles, they were dispersed in DMSO or water and were shown to retain their nanodimensions.

  2. Lipase catalyzed esterification of glycidol in organic solvents.

    Science.gov (United States)

    Martins, J F; Da Ponte, M N; Barreiros, S

    1993-08-05

    We studied the resolution of racemic glycidol through esterification with butyric acid catalyzed by porcine pancreatic lipase in organic media. A screening of seven solvents (log P values between 0.49 and 3.0, P being the n-octanol-water partition coefficient of the solvent) showed that neither log P nor the logarithm of the molar solubility of water in the solvent provides good correlations between enantioselectivity and the properties of the organic media. Chloroform was one of the best solvents as regards the enantiomeric purity (e. p.) of the ester produced. In this solvent, the optimum temperature for the reaction was determined to be 35 degrees C. The enzyme exhibited maximum activity at a water content of 13 +/- 2% (w/w). The enantiomeric purity obtained was 83 +/- 2% of (S)-glycidyl butyrate and did not depend on the alcohol concentration or the enzyme water content for values of these parameters up to 200 mM and 25% (w/w), respectively. The reaction was found to follow a BiBi mechanism.

  3. Hydrogen cycling of niobium and vanadium catalyzed nanostructured magnesium.

    Science.gov (United States)

    Schimmel, H Gijs; Huot, Jacques; Chapon, Laurent C; Tichelaar, Frans D; Mulder, Fokko M

    2005-10-19

    The reaction of hydrogen gas with magnesium metal, which is important for hydrogen storage purposes, is enhanced significantly by the addition of catalysts such as Nb and V and by using nanostructured powders. In situ neutron diffraction on MgNb(0.05) and MgV(0.05) powders give a detailed insight on the magnesium and catalyst phases that exist during the various stages of hydrogen cycling. During the early stage of hydriding (and deuteriding), a MgH(1hydrogen diffusion coefficient, partly explaining the enhanced kinetics of nanostructured magnesium. It is shown that under relevant experimental conditions, the niobium catalyst is present as NbH(1). Second, a hitherto unknown Mg-Nb perovskite phase could be identified that has to result from mechanical alloying of Nb and the MgO layer of the particles. Vanadium is not visible in the diffraction patterns, but electron micrographs show that the V particle size becomes very small, 2-20 nm. Nanostructuring and catalyzing the Mg enhance the adsorption speed that much that now temperature variations effectively limit the absorption speed and not, as for bulk, the slow kinetics through bulk MgH(2) layers.

  4. On Transition Metal Catalyzed Reduction of N-nitrosodimethlamine

    CERN Document Server

    Zhou, Jun; Tian, Junhua; Zhao, Zhun

    2014-01-01

    This report provides a critical review on "Metal-Catalyzed Reduction of N-Nitrosodimethylamine with Hydrogen in Water", by Davie et al. N-nitrosodimethlamine (NDMA) is a contaminant in drinking and ground water which is difficult to remove by conventional physical methods, such as air stripping. Based on the reported robust capability of metal based powder shaped catalysts in hydrogen reduction, several monometallic and bimetallic catalyst are studied in this paper on the reduction of NDMA with hydrogen. Two kinds of kinetics, metal weight normalized and surface area normalized, are compared between each catalyst in terms of pseudo-first order reaction rate. Palladium, copper enhanced palladium and nickel are found to be very efficient in NDMA reduction, with half-lives on the order of hours per 10 mg/l catalyst metal. Preliminary LC-MS data and carbon balance showed no intermediates. Finally, a simple hydrogen and NMDA surface activated reaction mechanism is proposed by the author for palladium and nickel.

  5. Production of chemoenzymatic catalyzed monoepoxide biolubricant: optimization and physicochemical characteristics.

    Science.gov (United States)

    Salimon, Jumat; Salih, Nadia; Abdullah, Bashar Mudhaffar

    2012-01-01

    Linoleic acid (LA) is converted to per-carboxylic acid catalyzed by an immobilized lipase from Candida antarctica (Novozym 435). This per-carboxylic acid is only intermediate and epoxidized itself in good yields and almost without consecutive reactions. Monoepoxide linoleic acid 9(12)-10(13)-monoepoxy 12(9)-octadecanoic acid (MEOA) was optimized using D-optimal design. At optimum conditions, higher yield% (82.14) and medium oxirane oxygen content (OOC) (4.91%) of MEOA were predicted at 15 μL of H(2)O(2), 120 mg of Novozym 435, and 7 h of reaction time. In order to develop better-quality biolubricants, pour point (PP), flash point (FP), viscosity index (VI), and oxidative stability (OT) were determined for LA and MEOA. The results showed that MEOA exhibited good low-temperature behavior with PP of -41(°)C. FP of MEOA increased to 128(°)C comparing with 115(°)C of LA. In a similar fashion, VI for LA was 224 generally several hundred centistokes (cSt) more viscous than MEOA 130.8. The ability of a substance to resist oxidative degradation is another important property for biolubricants. Therefore, LA and MEOA were screened to measure their OT which was observed at 189 and 168(°)C, respectively.

  6. Production of Chemoenzymatic Catalyzed Monoepoxide Biolubricant: Optimization and Physicochemical Characteristics

    Directory of Open Access Journals (Sweden)

    Jumat Salimon

    2012-01-01

    Full Text Available Linoleic acid (LA is converted to per-carboxylic acid catalyzed by an immobilized lipase from Candida antarctica (Novozym 435. This per-carboxylic acid is only intermediate and epoxidized itself in good yields and almost without consecutive reactions. Monoepoxide linoleic acid 9(12-10(13-monoepoxy 12(9-octadecanoic acid (MEOA was optimized using D-optimal design. At optimum conditions, higher yield% (82.14 and medium oxirane oxygen content (OOC (4.91% of MEOA were predicted at 15 μL of H2O2, 120 mg of Novozym 435, and 7 h of reaction time. In order to develop better-quality biolubricants, pour point (PP, flash point (FP, viscosity index (VI, and oxidative stability (OT were determined for LA and MEOA. The results showed that MEOA exhibited good low-temperature behavior with PP of −41°C. FP of MEOA increased to 128°C comparing with 115°C of LA. In a similar fashion, VI for LA was 224 generally several hundred centistokes (cSt more viscous than MEOA 130.8. The ability of a substance to resist oxidative degradation is another important property for biolubricants. Therefore, LA and MEOA were screened to measure their OT which was observed at 189 and 168°C, respectively.

  7. Palladium Catalyzed Allylic C-H Alkylation: A Mechanistic Perspective

    Directory of Open Access Journals (Sweden)

    Casper Junker Engelin

    2011-01-01

    Full Text Available The atom-efficiency of one of the most widely used catalytic reactions for forging C-C bonds, the Tsuji-Trost reaction, is limited by the need of preoxidized reagents. This limitation can be overcome by utilization of the recently discovered palladium-catalyzed C-H activation, the allylic C-H alkylation reaction which is the topic of the current review. Particular emphasis is put on current mechanistic proposals for the three reaction types comprising the overall transformation: C-H activation, nucleophillic addition, and re-oxidation of the active catalyst. Recent advances in C-H bond activation are highlighted with emphasis on those leading to C-C bond formation, but where it was deemed necessary for the general understanding of the process closely related C-H oxidations and aminations are also included. It is found that C-H cleavage is most likely achieved by ligand participation which could involve an acetate ion coordinated to Pd. Several of the reported systems rely on benzoquinone for re-oxidation of the active catalyst. The scope for nucleophilic addition in allylic C-H alkylation is currently limited, due to demands on pKa of the nucleophile. This limitation could be due to the pH dependence of the benzoquinone/hydroquinone redox couple. Alternative methods for re-oxidation that does not rely on benzoquinone could be able to alleviate this limitation.

  8. Kinetics of Platinum-Catalyzed Decomposition of Hydrogen Peroxide

    Science.gov (United States)

    Vetter, Tiffany A.; Colombo, D. Philip, Jr.

    2003-07-01

    CIBA Vision Corporation markets a contact lens cleaning system that consists of an AOSEPT disinfectant solution and an AOSEPT lens cup. The disinfectant is a buffered 3.0% m/v hydrogen peroxide solution and the cup includes a platinum-coated AOSEPT disc. The hydrogen peroxide disinfects by killing bacteria, fungi, and viruses found on the contact lenses. Because the concentration of hydrogen peroxide needed to disinfect is irritating to eyes, the hydrogen peroxide needs to be neutralized, or decomposed, before the contact lenses can be used again. A general chemistry experiment is described where the kinetics of the catalyzed decomposition of the hydrogen peroxide are studied by measuring the amount of oxygen generated as a function of time. The order of the reaction with respect to the hydrogen peroxide, the rate constant, and the energy of activation are determined. The integrated rate law is used to determine the time required to decompose the hydrogen peroxide to a concentration that is safe for eyes.

  9. Deoxycholic acid transformations catalyzed by selected filamentous fungi.

    Science.gov (United States)

    Kollerov, V V; Lobastova, T G; Monti, D; Deshcherevskaya, N O; Ferrandi, E E; Fronza, G; Riva, S; Donova, M V

    2016-03-01

    More than 100 filamentous fungi strains, mostly ascomycetes and zygomycetes from different phyla, were screened for the ability to convert deoxycholic acid (DCA) to valuable bile acid derivatives. Along with 11 molds which fully degraded DCA, several strains were revealed capable of producing cholic acid, ursocholic acid, 12-keto-lithocholic acid (12-keto-LCA), 3-keto-DCA, 15β-hydroxy-DCA and 15β-hydroxy-12-oxo-LCA as major products from DCA. The last metabolite was found to be a new compound. The ability to catalyze the introduction of a hydroxyl group at the 7(α/β)-positions of the DCA molecule was shown for 32 strains with the highest 7β-hydroxylase activity level for Fusarium merismoides VKM F-2310. Curvularia lunata VKM F-644 exhibited 12α-hydroxysteroid dehydrogenase activity and formed 12-keto-LCA from DCA. Acremonium rutilum VKM F-2853 and Neurospora crassa VKM F-875 produced 15β-hydroxy-DCA and 15β-hydroxy-12-oxo-LCA, respectively, as major products from DCA, as confirmed by MS and NMR analyses. For most of the positive strains, the described DCA-transforming activity was unreported to date. The presented results expand the knowledge on bile acid metabolism by filamentous fungi, and might be suitable for preparative-scale exploitation aimed at the production of marketed bile acids. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Kinetics of acid base catalyzed transesterification of Jatropha curcas oil.

    Science.gov (United States)

    Jain, Siddharth; Sharma, M P

    2010-10-01

    Out of various non-edible oil resources, Jatropha curcas oil (JCO) is considered as future feedstock for biodiesel production in India. Limited work is reported on the kinetics of transesterification of high free fatty acids containing oil. The present study reports the results of kinetic study of two-step acid base catalyzed transesterification process carried out at an optimum temperature of 65 °C and 50 °C for esterification and transesterification respectively under the optimum methanol to oil ratio of 3:7 (v/v), catalyst concentration 1% (w/w) for H₂SO₄ and NaOH. The yield of methyl ester (ME) has been used to study the effect of different parameters. The results indicate that both esterification and transesterification reaction are of first order with reaction rate constant of 0.0031 min⁻¹ and 0.008 min⁻¹ respectively. The maximum yield of 21.2% of ME during esterification and 90.1% from transesterification of pretreated JCO has been obtained.

  11. Acid-catalyzed production of biodiesel from waste frying oil

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, S.; Dube, M.A.; McLean, D.D. [Department of Chemical Engineering, University of Ottawa, Ottawa, ON (Canada); Kates, M. [Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON (Canada)

    2006-03-15

    The reaction kinetics of acid-catalyzed transesterification of waste frying oil in excess methanol to form fatty acid methyl esters (FAME), for possible use as biodiesel, was studied. Rate of mixing, feed composition (molar ratio oil:methanol:acid) and temperature were independent variables. There was no significant difference in the yield of FAME when the rate of mixing was in the turbulent range 100 to 600rpm. The oil:methanol:acid molar ratios and the temperature were the most significant factors affecting the yield of FAME. At 70{sup o}C with oil:methanol:acid molar ratios of 1:245:3.8, and at 80{sup o}C with oil:methanol:acid molar ratios in the range 1:74:1.9-1:245:3.8, the transesterification was essentially a pseudo-first-order reaction as a result of the large excess of methanol which drove the reaction to completion (99+/-1% at 4h). In the presence of the large excess of methanol, free fatty acids present in the waste oil were very rapidly converted to methyl esters in the first few minutes under the above conditions. Little or no monoglycerides were detected during the course of the reaction, and diglycerides present in the initial waste oil were rapidly converted to FAME. (author)

  12. Enzymatically catalyzed HES conjugation using microbial transglutaminase: Proof of feasibility.

    Science.gov (United States)

    Besheer, Ahmed; Hertel, Thomas C; Kressler, Jörg; Mäder, Karsten; Pietzsch, Markus

    2009-11-01

    Polymer-drug and polymer-protein conjugates are promising candidates for the delivery of therapeutic agents. PEGylation, using poly(ethylene glycol) for the conjugation, is now the gold standard in this field, and some PEGylated proteins have successfully reached the market. Hydroxyethyl starch (HES) is a water-soluble, biodegradable derivative of starch that is currently being investigated as a substitute for PEG. So far, only chemical methods have been suggested for HES conjugation; however, these may have detrimental effects on proteins. Here, we report an enzymatic method for HES conjugation using a recombinant microbial transglutaminase (rMTG). The latter catalyzes the acyl transfer between the gamma-carboxamide group of a glutaminyl residue (acyl donors) and a variety of primary amines (acyl acceptors), including the amino group of lysine. HES was modified with N-carbobenzyloxy glutaminyl glycine (Z-QG) and hexamethylene diamine (HMDA) to act as acyl donor and acyl acceptor, respectively. Using (1)H NMR, the degree of modification with Z-QG and HMDA was found to be 4.6 and 3.9 mol%, respectively. Using SDS-PAGE, it was possible to show that the modified HES successfully coupled to test compounds, proving that it is accepted as a substrate by rMTG. Finally, the process described in this study is a simple, mild approach to produce fully biodegradable polymer-drug and polymer-protein conjugates. (c) 2009 Wiley-Liss, Inc. and the American Pharmacists Association

  13. Cobalt-Catalyzed Vinylation of Organozinc Reagents with Aldehydes

    Institute of Scientific and Technical Information of China (English)

    WANG; JinXian

    2001-01-01

    Transtion metal catalyzed vinylation of organic halides are known to be a very convenient method for forming carbon-carbon bonds at unsubstituted vinylic position. The versatility of stilbenes is well known because of its various biological active components, the variety of its reactions in organic syntheses, and its ability to function as a bonding partner for metals in complexes.  Many methods have been described for the synthesis of stilbenes. The reduction, dehydrogenation, and elimination reactions leading to stilbenes without formation of new carbon-carbon bonds are known to be a very convenient methods. Synthetically more important are the dimerization reactions: oxidative or eleminative dimerization of a suitable methylarene often constitutes the method of choice for the preparation of a symmetric stilbene. Meerwein arylation and Heck reaction are prominent examples for the synthesis of stilbenes from arenes and styrenes. Moreover, condensation reactions of a nucleophilic with an electrophilic arylmethyl compound include Knoevenagel type reactions and the very general Wittig and Wittig-Horner reactions are also known methods.  ……

  14. Base-catalyzed depolymerization of lignin : separation of monomers

    Energy Technology Data Exchange (ETDEWEB)

    Vigneault, A. [Sherbrooke Univ., PQ (Canada). Dept. of Chemical Engineering; Johnson, D.K. [National Renewable Energy Laboratory, Golden, CO (United States); Chornet, E. [Sherbrooke Univ., PQ (Canada). Dept. of Chemical Engineering; National Renewable Energy Laboratory, Golden, CO (United States)

    2007-12-15

    Biofuels produced from residual lignocellulosic biomass range from ethanol to biodiesel. The use of lignin for the production of alternate biofuels and green chemicals has been studied with particular emphasis on the structure of lignin and its oxyaromatic nature. In an effort to fractionate lignocellulosic biomass and valorize specific constitutive fractions, the authors developed a strategy for the separation of 12 added value monomers produced during the hydrolytic base catalyzed depolymerization (BCD) of a Steam Exploded Aspen Lignin. The separation strategy was similar to vanillin purification to obtain pure monomers, but combining more steps after the lignin depolymerization such as acidification, batch liquid-liquid-extraction (LLE), followed by vacuum distillation, liquid chromatography (LC) and crystallization. The purpose was to develop basic data for an industrial size process flow diagram, and to evaluate both the monomer losses during the separation and the energy requirements. Experimentally testing of LLE, vacuum distillation and flash LC in the laboratory showed that batch vacuum distillation produced up to 4 fractions. Process simulation revealed that a series of 4 vacuum distillation columns could produce 5 distinct monomer streams, of which 3 require further chromatography and crystallization operations for purification. 22 refs., 4 tabs., 8 figs.

  15. Enzyme-catalyzed Sequential Reduction of Carbon Dioxide to Formaldehyde☆

    Institute of Scientific and Technical Information of China (English)

    Wenfang Liu; Yanhui Hou; Benxiang Hou; Zhiping Zhao

    2014-01-01

    It has been reported that enzymatic-catalyzed reduction of CO2 is feasible. Most of literature focuses on the con-version of CO2 to methanol. Herein we put emphasis on the sequential conversion of CO2 to formaldehyde and its single reactions. It appears that CO2 pressure plays a critical role and higher pressure is greatly helpful to form more HCOOH as well as HCHO. The reverse reaction became severe in the reduction of CO2 to formaldehyde after 10 h, decreasing HCHO production. Increasing the mass ratio of formate dehydrogenase to formaldehyde dehydrogenase could promote the sequential reaction. At concentrations of nicotinamide adenine dinucleotide lower than 100 mmol·L−1, the reduction of CO2 was accelerated by increasing cofactor concentration. The opti-mum pH value and concentration of phosphate buffer were determined as 6.0 and 0.05 mol·L−1, respectively, for the overall reaction. It seems that thermodynamic factor such as pH is restrictive to the sequential reaction due to distinct divergence in appropriate pH range between its single reactions.

  16. Alkylation of Benzene with Propylene Catalyzed by Ionic Liquids

    Institute of Scientific and Technical Information of China (English)

    Sun Xuewen; Zhao Suoqi

    2006-01-01

    The alkylation of benzene with propylene catalyzed by ionic liquids to obtain cumene was investigated. Propylene conversion and cumene selectivity under mild reaction conditions were improved greatly after the ionic liquid was modified with HCl. Under the conditions of 20 oC, 0.1MPa, 5 min of reaction time, and a molar ratio of benzene to propylene of 10:1, propylene conversion increased from 83.6% to 100%, and cumene selectivity increased from 90.86% to 98.47%. In addition, it was found that the reaction could be carried out in two different stages so as to obtain a better result. At the first stage, the key reaction was alkylation and a higher propylene conversion was obtained at a lower temperature;At the second stage, the key reaction was transalkylation and a higher temperature was used to improve cumene selectivity. The reaction temperature, pressure and the amount of catalyst used in this work were lower than those used in traditional alkylation processes.

  17. Broadening the scope of glycosyltransferase-catalyzed sugar nucleotide synthesis.

    Science.gov (United States)

    Gantt, Richard W; Peltier-Pain, Pauline; Singh, Shanteri; Zhou, Maoquan; Thorson, Jon S

    2013-05-07

    We described the integration of the general reversibility of glycosyltransferase-catalyzed reactions, artificial glycosyl donors, and a high throughput colorimetric screen to enable the engineering of glycosyltransferases for combinatorial sugar nucleotide synthesis. The best engineered catalyst from this study, the OleD Loki variant, contained the mutations P67T/I112P/T113M/S132F/A242I compared with the OleD wild-type sequence. Evaluated against the parental sequence OleD TDP16 variant used for screening, the OleD Loki variant displayed maximum improvements in k(cat)/K(m) of >400-fold and >15-fold for formation of NDP-glucoses and UDP-sugars, respectively. This OleD Loki variant also demonstrated efficient turnover with five variant NDP acceptors and six variant 2-chloro-4-nitrophenyl glycoside donors to produce 30 distinct NDP-sugars. This study highlights a convenient strategy to rapidly optimize glycosyltransferase catalysts for the synthesis of complex sugar nucleotides and the practical synthesis of a unique set of sugar nucleotides.

  18. Kinetics of phenolic polymerization catalyzed by peroxidase in organic media

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Y.P.; Huang, G.L; Yu, Y.T. [Nankai Univ., Tianjin (China). Inst. for Molecular Biology

    1995-07-05

    Phenolic polymerization was carried out by enzymatic catalysis in organic media, and its kinetics was studied by using high-pressure liquid chromatography (HPLC). Phenols and aromatic amines with electron-withdrawing groups could hardly be polymerized by HRP catalysis, but phenols and aromatic amines with electron-donating groups could easily by polymerized. The reaction rate of either the para-substituted substrate or meta-substituted substrate was higher than that of ortho-substituted substrate. When ortho-position of hydroxy group of phenols was occupied by an electron-donating group and if another electron-donating group occupied para-position of hydroxy group, the reaction rate increased. Horseradish peroxidase and lactoperoxidase could easily catalyze the polymerization, but chloroperoxidase and laccase failed to yield polymers. Metallic ions such as Mn{sup 2+}, Fe{sup 2+}, or Fe{sup 3+}, and Cu{sup 2+} could poison horseradish peroxidase to various extents, but ions such as Co{sup 2+}, Cd{sup 2+}, Zn{sup 2+}, and K{sup +} were not found to inhibit the reaction.

  19. Transamidation of carboxamides catalyzed by Fe(III) and water.

    Science.gov (United States)

    Becerra-Figueroa, Liliana; Ojeda-Porras, Andrea; Gamba-Sánchez, Diego

    2014-05-16

    The highly efficient transamidation of several primary, secondary, and tertiary amides with aliphatic and aromatic amines (primary and secondary) is described. The reaction is performed in the presence of a 5 mol % concentration of different hydrated salts of Fe(III), and the results show that the presence of water is crucial. The methodology was also applied to urea and phthalimide to demonstrate its versatility and wide substrate scope. An example of its use is an intramolecular application in the synthesis of 2,3-dihydro-5H-benzo[b]-1,4-thiazepin-4-one, which is the bicyclic core of diltiazem and structurally related drugs (Budriesi, R.; Cosimelli, B.; Ioan, P.; Carosati, E.; Ugenti, M. P.; Spisani, R. Curr. Med. Chem. 2007, 14, 279-287). A plausible mechanism that explains the role of water is proposed on the basis of experimental observations and previous mechanistic suggestions for transamidation reactions catalyzed by transition metals such as copper and aluminum. This methodology represents a significant improvement over other existing methods; it can be performed in air and with wet or technical grade solvents.

  20. Regiospecific Addition of Uracil to Acrylates Catalyzed by Alkaline Protease from Bacillus subtilis

    Institute of Scientific and Technical Information of China (English)

    Ying CAI; Jian Yi WU; Na WANG; Xiao Feng SUN; Xian Fu LIN

    2004-01-01

    Michael addition reactions of uracil to acrylates were catalyzed by an alkaline protease from Bacillus subtilis in dimethyl sulfoxide at 55 ℃ for 72 h. The adducts were determined by TLC, IR and 1H NMR.

  1. NOx-Catalyzed Gas-Phase Activation of Methane:the Formation of Hydrogen

    Institute of Scientific and Technical Information of China (English)

    Chaoxian Xiao; Zhen Yan; Yuan Kou

    2003-01-01

    NOx-catalyzed oxidation of methane without a solid catalyst was investigated, and a hydrogen selectivity of 27% was obtained with an overall methane conversion of 34% and a free O2 concentration of 1.7% at 700 ℃.

  2. Iridium-catalyzed annulation of salicylimines with 1,3-dienes.

    Science.gov (United States)

    Ebe, Yusuke; Nishimura, Takahiro

    2014-07-01

    Iridium-catalyzed annulation of salicylimines with 1,3-dienes gave high yields of the corresponding 4-aminochromanes with high stereoselectivity. The use of a chiral diene ligand enabled the asymmetric reaction to give 4-aminochromanes with high enantioselectivity.

  3. From the molecule to the mole: improving heterogeneous copper catalyzed click chemistry using single molecule spectroscopy.

    Science.gov (United States)

    Wang, Bowen; Durantini, Javier; Decan, Matthew R; Nie, Jun; Lanterna, Anabel E; Scaiano, Juan C

    2016-12-22

    Single molecule spectroscopy (SMS) inspired the optimization of a heterogeneous 'click' catalyst leading to enhanced yields of the Cu-catalyzed reaction of azides with terminal alkynes. Changes in SMS data after optimization confirm the improvements in catalyst performance.

  4. Rhodium-Catalyzed Transannulation of 1,2,3-Triazoles with Nitriles

    Science.gov (United States)

    Horneff, Tony; Chuprakov, Stepan; Chernyak, Natalia

    2009-01-01

    Stable and readily available 1-sulfonyl triazoles are converted to the corresponding imidazoles in good to excellent yields via a rhodium(II)-catalyzed reaction with nitriles. Rhodium iminocarbenoids are proposed intermediates. PMID:18855475

  5. Self-catalyzed Effect and Cracking Risk in Mass Concrete Containing Micro-slag

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The main results obtained from the experimental and engineering investigation on the heat evolution and cracking risk of a furnace concrete block were presented. The heat evolution of experimental mortars containing micro-slag under different environmental temperatures was instrumented in order to investigate the self-catalyzed effect, which was discovered in engineering. Moreover, the thermal stress of the furnace concrete due to heat temperature rise was calculated to evaluate the cracking risk of mass concrete containing micro-slag due to self-catalyzed effect. The experimental results illustrate that with the development of hydration and initial temperature of mixture, the hydration can be also accelerated and temperature of concrete will be continued to rise, which was the self-catalyzed effect. And the thermal stress due to self-catalyzed effect could not result in the cracking of furnace concrete.

  6. The applications of Schiff bases in Ti-catalyzed asymmetric alkynylation of aldehydes

    Institute of Scientific and Technical Information of China (English)

    Xian Jia; Lu Yin; Xuan Zhao; Xing Shu Li

    2007-01-01

    Sciff bases 1 and 2, which were derived from chiral aminoalcohols, were used as ligands in Ti-catalyzed asymmetric alkynylation of aldehydes. Good enantioselectivities (up to 88% ee) and high chemical yields (80-90 %) were obtained.

  7. Solid Nanoparticles That Catalyze Biofuel Upgrade Reactions at the Water/Oil Interface

    National Research Council Canada - National Science Library

    Steven Crossley; Jimmy Faria; Min Shen; Daniel E. Resasco

    2010-01-01

    ... of crude products greatly complicates purification procedures. Here, we report a family of solid catalysts that can stabilize water-oil emulsions and catalyze reactions at the liquid/liquid interface...

  8. Palladium-catalyzed Cascade Cyclization-Coupling Reaction of Benzyl Halides with N,N-Diallylbenzoylamide

    Institute of Scientific and Technical Information of China (English)

    Yi Min HU; Yu ZHANG; Jian Lin HAN; Cheng Jian ZHU; Yi PAN

    2003-01-01

    A novel type of palladium-catalyzed cascade cyclization-coupling reaction has been found. Reaction of N, N-diallylbenzoylamide 1 with benzyl halides 2 afforded the corresponding dihydropyrroles 3 in moderate to excellent yields.

  9. Hydrolysis of Toxic Natural Glucosides Catalyzed by Cyclodextrin Dicyanohydrins

    DEFF Research Database (Denmark)

    Bjerre, Jeannette; Nielsen, Erik Holm; Bols, Mikael

    2008-01-01

    The hydrolysis of toxic 7-hydroxycoumarin glucosides and other aryl and alkyl glucosides, catalyzed by modified a- and ß-cyclodextrin dicyanohydrins, was investigated using different UV, redox, or HPAEC detection assays. The catalyzed reactions all followed Michaelis-Menten kinetics, and an impre......The hydrolysis of toxic 7-hydroxycoumarin glucosides and other aryl and alkyl glucosides, catalyzed by modified a- and ß-cyclodextrin dicyanohydrins, was investigated using different UV, redox, or HPAEC detection assays. The catalyzed reactions all followed Michaelis-Menten kinetics......, and an impressive rate increase of up to 7569 (kcat/kuncat) was found for the hydroxycoumarin glucoside substrate 4-MUGP. Good and moderate degrees of catalysis (kcat/kuncat) of up to 1259 were found for the natural glucosides phloridzin and skimmin. By using a newly developed catechol detection UV-assay, a weak...

  10. Organizational innovation: verifying a comprehensive model for catalyzing organizational development and change

    National Research Council Canada - National Science Library

    Steiber, Annika; Alänge, Sverker

    2015-01-01

    .... Previous research has identified a need for a more comprehensive framework that will aid in better understanding of the mechanisms catalyzing organizational development and change. Steiber and Alänge (Triple Helix 2(9):1–25, 2015...

  11. PALLADIUM-CATALYZED OXIDATION OF STYRENE AND ALKENES IN PRESENCE OF IONIC LIQUIDS (WACKER REACTION)

    Science.gov (United States)

    The use of ionic liquids in various synthetic transformations is gaining significance due to the enhanced reaction rates, potential for recycling and compatibility with various organic compounds and organometallic catalysts. Palladium-catalyzed oxidation of styrene and other alk...

  12. Highly Efficient Synthesis of Bis(indolyl)methanes Catalyzed by Sodium Tetrafluoroborate

    Institute of Scientific and Technical Information of China (English)

    KAMBLE,Vinod Tribhuvannathji; BANDGAR,Babasaheb Pandurang; BAVIKAR,Sudhir Narayanrao

    2007-01-01

    Sodium tetrafluoroborate (NaBF4) was found to catalyze the electrophilic substitution reactions of indoles with aldehydes and ketones under solvent-free conditions to afford the corresponding bis(indolyl)methanes in high yields.

  13. Highly enantioselective [4 + 2] cyclization of chloroaldehydes and 1-azadienes catalyzed by N-heterocyclic carbenes.

    Science.gov (United States)

    Jian, Teng-Yue; Sun, Li-Hui; Ye, Song

    2012-11-14

    Highly functionalized dihydropyridinones were synthesized via the N-heterocyclic carbene-catalyzed enantioselective [4 + 2] annulation of α-chloroaldehydes and azadienes. Hydrogenation of the resulted dihydropyridinones afforded the corresponding piperidinones with high enantiopurity.

  14. Three-component synthesis of amidoalkyl naphthols catalyzed by bismuth(Ⅲ) nitrate pentahydrate

    Institute of Scientific and Technical Information of China (English)

    Min Wang; Yan Liang; Ting Ting Zhang; Jing Jing Gao

    2012-01-01

    Bismuth(Ⅲ) nitrate pentahydrate catalyzed the three-component condensation of β-naphthol,aldehydes and amines/urea under solvent-free conditions to afford the corresponding amidoalkyl naphthols in excellent yields.

  15. Regioselective Palladium-Catalyzed Cross-Coupling Reactions of 2,4,7-Trichloroquinazoline.

    Science.gov (United States)

    Wipf, Peter; George, Kara M

    2010-03-01

    The regioselective palladium-catalyzed cross-coupling reactions of 2,4,7-trichloroquinazoline with various aryl- and heteroarylboronic acids are reported. An efficient, sequential strategy was developed that provides access to novel, functionalized heterocycles.

  16. GREEN CATALYZED OXIDATION OF HYDROCARBONS IN ALTERNATIVE SOLVENT SYSTEMS GENERATED BY PARIS II

    Science.gov (United States)

    Green Catalyzed Oxidation of Hydrocarbons in Alternative Solvent Systems Generated by PARIS IIMichael A. Gonzalez*, Thomas M. Becker, and Paul F. Harten; Sustainable Technology Division, Office of Research and Development; United States Environmental Protection Agency, 26...

  17. Hydroaminomethylation of 1-Dodecene Catalyzed by Water-soluble Rhodium Complex

    Institute of Scientific and Technical Information of China (English)

    Ying Yong WANG; Mei Ming LUO; Yao Zhong LI; Hua CHEN; Xian Jun LI

    2004-01-01

    The hydroaminomethylation of 1-dodecene catalyzed by water soluble rhodium complex RhCl(CO)(TPPTS)2 in the presence of surfactant CTAB was investigated. High reactivity and selectivity for tertiary amine were achieved under relatively mild conditions.

  18. Horseradish peroxidase catalyzed free radical cannot free move in reaction solution

    OpenAIRE

    2009-01-01

    Mechanism of Horseradish Peroxidase -catalyzed phenol compound oxidizing reaction is a radical polymerization. Many polymer preparation are also carry on through the radical polymerization mechanism We deduce if free radical produced by peroxidasecatalyzed phenol polymerization could apply on polymer preparation? Could the phenol–oxygen free radical leave off the peroxidase and catalyze other compounds polymerization? The free radical in phenol oxidation process was investigated in homo...

  19. Ready Access to the Echinopines Skeleton via Gold(I)-Catalyzed Alkoxycyclizations of Enynes

    Science.gov (United States)

    2016-01-01

    The [3,5,5,7] tetracyclic skeleton of echinopines has been stereoselectively accessed through a gold(I)-catalyzed alkoxycyclization of cyclopropyl-tethered 1,6-enynes. The key bicyclo[4.2.1]nonane core of the enyne precursors was readily assembled by means of a Co-catalyzed [6 + 2] cycloaddition. Furthermore, the attempted alkoxycyclization of 1,5-enyne substrates revealed an uncovered cyclopropyl rearrangement that gives rise to [3,6,5,7] tetracyclic structures. PMID:27529429

  20. Palladium-catalyzed carbonylative Sonogashira coupling of aryl bromides via tert-butyl isocyanide insertion.

    Science.gov (United States)

    Tang, Ting; Fei, Xiang-Dong; Ge, Zhi-Yuan; Chen, Zhong; Zhu, Yong-Ming; Ji, Shun-Jun

    2013-04-05

    A simple and efficient palladium-catalyzed carbonylative Sonogashira coupling via tert-butyl isocyanide insertion has been developed, which demonstrates the utility of isocyanides in intermolecular C-C bond construction. This methodology provides a novel pathway for the synthesis of alkynyl imines which can undergo simple silica gel catalyzed hydrolysis to afford alkynones. The approach is tolerant of a wide range of substrates and applicable to library synthesis.

  1. Multidirectional Synthesis of Substituted Indazoles via Iridium-Catalyzed C-H Borylation.

    Science.gov (United States)

    Sadler, Scott A; Hones, Andrew C; Roberts, Bryan; Blakemore, David; Marder, Todd B; Steel, Patrick G

    2015-05-15

    In the absence of a steric directing group, iridium-catalyzed C-H borylation of N-protected indazoles occurs rapidly and selectively at C-3 and the resulting boronate esters can be utilized in a range of downstream conversions. The functional group tolerance of the iridium-catalyzed C-H borylation reaction enables simple and efficient multidirectional syntheses of substituted indazoles to be realized.

  2. Palladium-Catalyzed Nucleophilic Substitution of Alcohols : Mechanistic Studies and Synthetic Applications

    OpenAIRE

    Sawadjoon, Supaporn

    2013-01-01

    This thesis deals with the palladium-catalyzed nucleophilic substitution of π-activated alcohols in which the C–O bond of a non-manipulated hydroxyl group is cleaved. The thesis is divided in two chapters describing two different catalytic systems. Chapter 2 describes a heterogeneous palladium-catalyzed transfer hydrogenolysis of primary, secondary, and tertiary benzylic alcohols to generate the corresponding aromatic hydrocarbons using formic acid as the hydrogen donor. A detailed mechanisti...

  3. Modeling Lipase-Catalyzed Biodiesel Production in [BMIM][PF6

    OpenAIRE

    JianJun Yang; MingYan Yang

    2016-01-01

    Lipase-catalyzed biodiesel production models in room temperature ionic liquids (RTILs) reaction medium available in the literature are valid especially for mixing intensity. In this paper, a preliminary model is established in order to try to describe the lipase-catalyzed biodiesel production process in RTILs in a stirring type bioreactor. Mixing intensity and time delay were inspected for the reaction model in [BMIM][PF6] medium. As a result, this model is a good explanation for these actual...

  4. Biodiesel Production from Spent Fish Frying Oil Through Acid-Base Catalyzed Transesterification

    OpenAIRE

    Abdalrahman B. Fadhil; Mohammed M. Dheyab; Kareem M. Ahmed; Marwa H. Yahya

    2012-01-01

    Biodiesel fuels were prepared from a special type of frying oil namely spent fish frying oil through two step transesterification viz. acid-base catalyzed transesterification. Hydrochloric acid and potassium hydroxide with methanol were used for this purpose. The oil was pre-treated with (1.0 wt% HCl) and methanol to reduce free fatty acids content of the oil. Then, conditions of the base catalyzed step such as base concentration, reaction temperature, methanol to oil molar ratio and reaction...

  5. Ready Access to the Echinopines Skeleton via Gold(I)-Catalyzed Alkoxycyclizations of Enynes.

    Science.gov (United States)

    Dorel, Ruth; Echavarren, Antonio M

    2016-09-16

    The [3,5,5,7] tetracyclic skeleton of echinopines has been stereoselectively accessed through a gold(I)-catalyzed alkoxycyclization of cyclopropyl-tethered 1,6-enynes. The key bicyclo[4.2.1]nonane core of the enyne precursors was readily assembled by means of a Co-catalyzed [6 + 2] cycloaddition. Furthermore, the attempted alkoxycyclization of 1,5-enyne substrates revealed an uncovered cyclopropyl rearrangement that gives rise to [3,6,5,7] tetracyclic structures.

  6. Mo-catalyzed asymmetric olefin metathesis in target-oriented synthesis: Enantioselective synthesis of (+)-africanol

    Science.gov (United States)

    Weatherhead, Gabriel S.; Cortez, G. A.; Schrock, Richard R.; Hoveyda, Amir H.

    2004-01-01

    Catalytic asymmetric ring-opening metathesis (AROM) provides an efficient method for the synthesis of a variety of optically enriched small organic molecules that cannot be easily prepared by alternative methods. The development of Mo-catalyzed AROM transformations that occur in tandem with ring-closing metathesis are described. The utility of the Mo-catalyzed AROM/ring-closing metathesis is demonstrated through an enantioselective approach to the synthesis of (+)-africanol. PMID:15056762

  7. Cyclization strategies to polyenes using Pd(II)-catalyzed couplings of pinacol vinylboronates.

    Science.gov (United States)

    Iafe, Robert G; Chan, Daniel G; Kuo, Jonathan L; Boon, Byron A; Faizi, Darius J; Saga, Tomomi; Turner, Jonathan W; Merlic, Craig A

    2012-08-17

    As a complement to Pd(0)-catalyzed cyclizations, seven Pd(II)-catalyzed cyclization strategies are reported. α,ω-Diynes are selectively hydroborated to bis(boronate esters), which cyclize under Pd(II)-catalysis producing a diverse array of small, medium, and macrocyclic polyenes with controlled E,E, Z,Z, or E,Z stereochemistry. Various functional groups are tolerated including aryl bromides, and applications are illustrated.

  8. Silver-Catalyzed Decarboxylative Addition/Cyclization of Activated Alkenes with Aliphatic Carboxylic Acids.

    Science.gov (United States)

    Xia, Xiao-Feng; Zhu, Su-Li; Chen, Chao; Wang, Haijun; Liang, Yong-Min

    2016-02-05

    A silver-catalyzed decarboxylative addition/aryl migration/desulfonylation of N-phenyl-N-(phenylsulfonyl)methacrylamide with primary, secondary, and tertiary carboxylic acids was described. The protocol provides an efficient approach for the synthesis of α-all-carbon quaternary stereocenters amides and isoquinolinediones. It was proposed that the radical generated from the silver-catalyzed decarboxylation was involved in the sequence reaction.

  9. Use of a palladium(II)-catalyzed oxidative kinetic resolution in synthetic efforts toward bielschowskysin.

    Science.gov (United States)

    Meyer, Michael E; Phillips, John H; Ferreira, Eric M; Stoltz, Brian M

    2013-09-09

    Progress toward the cyclobutane core of bielshowskysin is reported. The core was thought to arise from a cyclopropane intermediate via a furan-mediated cyclopropane fragmentation, followed by a 1,4-Michael addition. The synthesis of the cyclopropane intermediate utilizes a Suzuki coupling reaction, an esterification with 2-diazoacetoacetic acid, and a copper catalyzed cyclopropanation. An alcohol intermediate within the synthetic route was obtained in high enantiopurity via a highly selective palladium(II)-catalyzed oxidative kinetic resolution (OKR).

  10. NMR spectroscopic investigations on copper-catalyzed reactions and zintl anions

    OpenAIRE

    Koch, Carina

    2016-01-01

    The copper-catalyzed asymmetric conjugated 1,4-addition reaction of organozinc reagents to a,b-unsaturated compounds is a very effective and widely used method for the enantioselective carbon-carbon bond formation. By the use of phosphoramidite ligands it is possible to reach ee-values and conversion up to > 99 %. Furthermore, this outstanding reaction provides lower costs in comparison to other transition-metal catalyzed reactions and compatibility to many functional groups. Despite the grea...

  11. Direct Evidence of a Dinuclear Copper Intermediate in Cu(I)-Catalyzed Azide–Alkyne Cycloadditions

    OpenAIRE

    Worrell, B. T.; Malik, J.A.; FOKIN, V.V.

    2013-01-01

    The copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) has become a commonly employed method for the synthesis of complex molecular architectures under challenging conditions. Despite the widespread use of copper-catalyzed cycloaddition reactions, the mechanism of these processes has remained difficult to establish due to the involvement of multiple equilibria between several reactive intermediates. Real-time monitoring of a representative cycloaddition process via heat flow reaction calo...

  12. The mechanism for iron-catalyzed alkene isomerization in solution

    Energy Technology Data Exchange (ETDEWEB)

    Sawyer, Karma R.; Glascoe, Elizabeth A.; Cahoon, James F.; Schlegel, Jacob P.; Harris, Charles B.

    2008-05-27

    Here we report nano- through microsecond time-resolved IR experiments of iron-catalyzed alkene isomerization in room-temperature solution. We have monitored the photochemistry of a model system, Fe(CO){sub 4}({eta}{sup 2}-1-hexene), in neat 1-hexene solution. UV-photolysis of the starting material leads to the dissociation of a single CO to form Fe(CO){sub 3}({eta}{sup 2}-1-hexene), in a singlet spin state. This CO loss complex shows a dramatic selectivity to form an allyl hydride, HFe(CO){sub 3}({eta}{sup 3}-C{sub 6}H{sub 11}), via an internal C-H bond-cleavage reaction in 5-25 ns. We find no evidence for the coordination of an alkene molecule from the bath to the CO loss complex, but do observe coordination to the allyl hydride, indicating that it is the key intermediate in the isomerization mechanism. Coordination of the alkene ligand to the allyl hydride leads to the formation of the bis-alkene isomers, Fe(CO){sub 3}({eta}{sup 2}-1-hexene)({eta}{sup 2}-2-hexene) and Fe(CO){sub 3}({eta}{sup 2}-1-hexene){sub 2}. Because of the thermodynamic stability of Fe(CO){sub 3}({eta}{sup 2}-1-hexene)({eta}{sup 2}-2-hexene) over Fe(CO){sub 3}({eta}{sup 2}-1-hexene){sub 2} (ca. 12 kcal/mol), nearly 100% of the alkene population will be 2-alkene. The results presented herein provide the first direct evidence for this mechanism in solution and suggest modifications to the currently accepted mechanism.

  13. Trinucleotide repeat expansions catalyzed by human cell-free extracts

    Institute of Scientific and Technical Information of China (English)

    Jennifer R Stevens; Elaine E Lahue; Guo-Min Li; Robert S Lahue

    2013-01-01

    Trinucleotide repeat expansions cause 17 heritable human neurological disorders.In some diseases,somatic expansions occur in non-proliferating tissues such as brain where DNA replication is limited.This finding stimulated significant interest in replication-independent expansion mechanisms.Aberrant DNA repair is a likely source,based in part on mouse studies showing that somatic expansions are provoked by the DNA repair protein MutSβ (Msh2-Msh3complex).Biochemical studies to date used cell-free extracts or purified DNA repair proteins to yield partial reactions at triplet repeats.The findings included expansions on one strand but not the other,or processing of DNA hairpin structures thought to be important intermediates in the expansion process.However,it has been difficult to recapitulate complete expansions in vitro,and the biochemical role of MutSβ remains controversial.Here,we use a novel in vitro assay to show that human cell-free extracts catalyze expansions and contractions of trinucleotide repeats without the requirement for DNA replication.The extract promotes a size range of expansions that is similar to certain diseases,and triplet repeat length and sequence govern expansions in vitro as in vivo.MutSβ stimulates expansions in the extract,consistent with aberrant repair of endogenous DNA damage as a source of expansions.Overall,this biochemical system retains the key characteristics of somatic expansions in humans and mice,suggesting that this important mutagenic process can be restored in the test tube.

  14. A review on biodiesel production using catalyzed transesterification

    Energy Technology Data Exchange (ETDEWEB)

    Leung, Dennis Y.C.; Wu, Xuan; Leung, M.K.H. [Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong (China)

    2010-04-15

    Biodiesel is a low-emissions diesel substitute fuel made from renewable resources and waste lipid. The most common way to produce biodiesel is through transesterification, especially alkali-catalyzed transesterification. When the raw materials (oils or fats) have a high percentage of free fatty acids or water, the alkali catalyst will react with the free fatty acids to form soaps. The water can hydrolyze the triglycerides into diglycerides and form more free fatty acids. Both of the above reactions are undesirable and reduce the yield of the biodiesel product. In this situation, the acidic materials should be pre-treated to inhibit the saponification reaction. This paper reviews the different approaches of reducing free fatty acids in the raw oil and refinement of crude biodiesel that are adopted in the industry. The main factors affecting the yield of biodiesel, i.e. alcohol quantity, reaction time, reaction temperature and catalyst concentration, are discussed. This paper also described other new processes of biodiesel production. For instance, the Biox co-solvent process converts triglycerides to esters through the selection of inert co-solvents that generates a one-phase oil-rich system. The non-catalytic supercritical methanol process is advantageous in terms of shorter reaction time and lesser purification steps but requires high temperature and pressure. For the in situ biodiesel process, the oilseeds are treated directly with methanol in which the catalyst has been preciously dissolved at ambient temperatures and pressure to perform the transesterification of oils in the oilseeds. This process, however, cannot handle waste cooking oils and animal fats. (author)

  15. Electrochemically Protected Copper(I)-Catalyzed Azide-Alkyne Cycloaddition

    Science.gov (United States)

    Hong, Vu; Udit, Andrew K.; Evans, Richard A.; Finn, M.G.

    2012-01-01

    The copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has found broad application in myriad fields. For the most demanding applications requiring high yields at low substrate concentrations, highly active but air-sensitive copper complexes must be used. We describe here the use of an electrochemical potential to maintain catalysts in the active Cu(I) oxidation state in the presence of air. The simple procedure efficiently achieves excellent yields of CuAAC products involving both small molecule and protein substrates without the use of potentially damaging chemical reducing agents. A new water-soluble carboxylated version of the popular tris(benzyltriazolylmethyl)amine (TBTA) ligand is described. Cyclic voltammetry revealed reversible or quasi-reversible electrochemical redox behavior of copper complexes of the TBTA derivative (2; E1/2 = 60 mV vs. Ag/AgCl), sulfonated bathophenanthroline (3; E1/2 = -60 mV), and sulfonated tris(benzimidazoylmethyl)amine (4; E1/2 ~ -70 mV), and showed catalytic turnover to be rapid relative to the voltammetry time scale. Under the influence of a -200 mV potential established using a reticulated vitreous carbon working electrode, CuSO4 and 3 formed a superior catalyst. Electrochemically-protected bioconjugations in air were performed using bacteriophage Qβ derivatized with azide moieties at surface lysine residues. The complete addressing of more than 600 reactive sites per particle was demonstrated within 12 hours of electrolysis with sub-stoichiometric quantities of Cu•3. PMID:18504727

  16. Electrochemically protected copper(I)-catalyzed azide-alkyne cycloaddition.

    Science.gov (United States)

    Hong, Vu; Udit, Andrew K; Evans, Richard A; Finn, M G

    2008-06-16

    The copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has found broad application in myriad fields. For the most demanding applications that require high yields at low substrate concentrations, highly active but air-sensitive copper complexes must be used. We describe here the use of an electrochemical potential to maintain catalysts in the active Cu(I) oxidation state in the presence of air. This simple procedure efficiently achieves excellent yields of CuAAC products from both small-molecule and protein substrates without the use of potentially damaging chemical reducing agents. A new water-soluble carboxylated version of the popular tris(benzyltriazolylmethyl)amine (TBTA) ligand is also described. Cyclic voltammetry revealed reversible or quasi-reversible electrochemical redox behavior of copper complexes of the TBTA derivative (2; E(1/2)=60 mV vs. Ag/AgCl), sulfonated bathophenanthroline (3; E(1/2)=-60 mV), and sulfonated tris(benzimidazoylmethyl)amine (4; E(1/2) approximately -70 mV), and showed catalytic turnover to be rapid relative to the voltammetry time scale. Under the influence of a -200 mV potential that was established by using a reticulated vitreous carbon working electrode, CuSO4 and 3 formed a superior catalyst. Electrochemically protected bioconjugations in air were performed by using bacteriophage Qbeta that was derivatized with azide moieties at surface lysine residues. Complete derivatization of more than 600 reactive sites per particle was demonstrated within 12 h of electrolysis with substoichiometric quantities of Cu3.

  17. Myeloperoxidase-catalyzed chlorination: the quest for the active species.

    Science.gov (United States)

    Ramos, Daniel R; García, M Victoria; Canle L, Moisés; Santaballa, J Arturo; Furtmüller, Paul G; Obinger, Christian

    2008-01-01

    Myeloperoxidase (MPO) is a dominating enzyme of circulating polymorphonuclear neutrophils that catalyzes the two-electron oxidation of chloride, thereby producing the strong halogenating agent hypochlorous acid (ClO(-)/HOCl). In absence of MPO the tripeptide Pro-Gly-Gly reacts with HOCl faster than the amino acid taurine (2-aminoethanesulfonic acid, Tau), while the MPO-mediated chlorination shows reverse order. A comparative study of the enzymatic oxidation of both substrates at pH 4.0-6.0, varying H2O2 concentration is presented. Initial and equilibrium rates studies have been carried on, reaction rates in the latter being slower due to the chemical equilibrium between MPO-I and MPO-II-HO2. A maximum of chlorination rate is observed for Pro-Gly-Gly and Tau when [H2O2] approximately 0.3-0.7 mM and pH approximately 4.5-5.0. Several mechanistic possibilities are considered, the proposed one implies that chlorination takes place via two pathways. One, for bulkier substrates, involves chlorination by free HOCl outside the heme cavity; ClO(-) is released from the active center, diffuses away the heme cavity, and undergoes protonation to HOCl. The other implies the existence of compound I-Cl(-) complex (MPO-I-Cl), capable of chlorinating smaller substrates in the heme pocket. Electronic structure calculations show the size of Pro-Gly-Gly comparable to the available gap in the substrate channel, this tripeptide being unable to reach the active site, and its chlorination is only possible by free HOCl outside the enzyme.

  18. Copper-Catalyzed Click Reaction on/in Live Cells.

    Science.gov (United States)

    Li, Siheng; Wang, Lin; Yu, Fei; Zhu, Zhiling; Shobaki, Dema; Chen, Haoqing; Wang, Mu; Wang, Jun; Qin, Guoting; Erasquin, Uriel J; Ren, Li; Wang, Yingjun; Cai, Chengzhi

    2017-03-01

    We demonstrated that copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction could be performed inside live mammalian cells without using a chelating azide. Under optimized conditions, the reaction was performed in human ovary cancer cell line OVCAR5 in which newly synthesized proteins were metabolically modified with homopropargylglycine (HPG). This model system allowed us to estimate the efficiency of the reaction on the cell membranes and in the cytosol using mass spectrometry. We found that the reaction was greatly promoted by a tris(triazolylmethyl)amine Cu(I) ligand tethering a cell-penetrating peptide. Uptake of the ligand, copper, and a biotin-tagged azide in the cells was determined to be 69 ± 2, 163 ± 3 and 1.3 ± 0.1 µM, respectively. After 10 minutes of reaction, the product yields on the membrane and cytosolic proteins were higher than 18% and 0.8%, respectively, while 75% cells remained viable. By reducing the biothiols in the system by scraping or treatment with N-ethylmalemide, the reaction yield on the cytosolic proteins was greatly improved to ~9% and ~14%, respectively, while the yield on the membrane proteins remained unchanged. The results indicate that out of many possibilities, deactivation of the current copper catalysts by biothiols is the major reason for the low yield of CuAAC reaction in the cytosol. Overall, we have improved the efficiency for CuAAC reaction on live cells by 3-fold. Despite the low yielding inside live cells, the products that strongly bind to the intracellular targets can be detected by mass spectrometry. Hence, the in situ CuAAC reaction can be potentially used for screening of cell-specific enzyme inhibitors or biomarkers containing 1,4-substituted 1,2,3-triazoles.

  19. Copper-catalyzed azide alkyne cycloaddition polymer networks

    Science.gov (United States)

    Alzahrani, Abeer Ahmed

    The click reaction concept, introduced in 2001, has since spurred the rapid development and reexamination of efficient, high yield reactions which proceed rapidly under mild conditions. Prior to the discovery of facile copper catalysis in 2002, the thermally activated azide-alkyne or Huisgen cycloaddition reaction was largely ignored following its discovery in large part due to its slow kinetics, requirement for elevated temperature and limited selectivity. Now, arguably, the most prolific and capable of the click reactions, the copper-catalyzed azide alkyne cycloaddition (CuAAC) reaction is extremely efficient and affords exquisite control of the reaction. The orthogonally and chemoselectivity of this reaction enable its wide utility across varied scientific fields. Despite numerous inherent advantages and widespread use for small molecule synthesis and solution-based polymer chemistry, it has only recently and rarely been utilized to form polymer networks. This work focuses on the synthesis, mechanisms, and unique attributes of the CuAAC reaction for the fabrication of functional polymer networks. The photo-reduction of a series of copper(II)/amine complexes via ligand metal charge transfer was examined to determine their relative efficiency and selectivity in catalyzing the CuAAC reaction. The aliphatic amine ligands were used as an electron transfer species to reduce Cu(II) upon irradiation with 365 nm light while also functioning as an accelerating agent and as protecting ligands for the Cu(I) that was formed. Among the aliphatic amines studied, tertiary amines such as triethylamine (TEA), tetramethyldiamine (TMDA), N,N,N',N",N"-pentamethyldiethylenetriamine (PMDTA), and hexamethylenetetramine (HMTETA) were found to be the most effective. The reaction kinetics were accelerated by increasing the PMDETA : Cu(II) ratio with a ratio of ligand to Cu(II) of 4:1 yielding the maximum conversion in the shortest time. The sequential and orthogonal nature of the photo

  20. The mechanism of the NHC catalyzed aza-Morita-Baylis-Hillman reaction: insights into a new substrate-catalyzed bimolecular pathway.

    Science.gov (United States)

    Verma, Pritha; Verma, Pragya; Sunoj, Raghavan B

    2014-04-14

    The first mechanistic study on the NHC-catalyzed aza-MBH reaction between cyclopentenone and N-mesylbenzaldimine using density functional theory reveals that a bimolecular mechanism, involving two molecules of benzaldimine in the proton transfer, is energetically more preferred over the conventional direct proton transfer.

  1. Growth and characterization of gold catalyzed SiGe nanowires and alternative metal-catalyzed Si nanowires

    Directory of Open Access Journals (Sweden)

    Gentile Pascal

    2011-01-01

    Full Text Available Abstract The growth of semiconductor (SC nanowires (NW by CVD using Au-catalyzed VLS process has been widely studied over the past few years. Among others SC, it is possible to grow pure Si or SiGe NW thanks to these techniques. Nevertheless, Au could deteriorate the electric properties of SC and the use of other metal catalysts will be mandatory if NW are to be designed for innovating electronic. First, this article's focus will be on SiGe NW's growth using Au catalyst. The authors managed to grow SiGe NW between 350 and 400°C. Ge concentration (x in Si1- x Ge x NW has been successfully varied by modifying the gas flow ratio: R = GeH4/(SiH4 + GeH4. Characterization (by Raman spectroscopy and XRD revealed concentrations varying from 0.2 to 0.46 on NW grown at 375°C, with R varying from 0.05 to 0.15. Second, the results of Si NW growths by CVD using alternatives catalysts such as platinum-, palladium- and nickel-silicides are presented. This study, carried out on a LPCVD furnace, aimed at defining Si NW growth conditions when using such catalysts. Since the growth temperatures investigated are lower than the eutectic temperatures of these Si-metal alloys, VSS growth is expected and observed. Different temperatures and HCl flow rates have been tested with the aim of minimizing 2D growth which induces an important tapering of the NW. Finally, mechanical characterization of single NW has been carried out using an AFM method developed at the LTM. It consists in measuring the deflection of an AFM tip while performing approach-retract curves at various positions along the length of a cantilevered NW. This approach allows the measurement of as-grown single NW's Young modulus and spring constant, and alleviates uncertainties inherent in single point measurement.

  2. Polymer multilayer films obtained by electrochemically catalyzed click chemistry.

    Science.gov (United States)

    Rydzek, Gaulthier; Thomann, Jean-Sébastien; Ben Ameur, Nejla; Jierry, Loïc; Mésini, Philippe; Ponche, Arnaud; Contal, Christophe; El Haitami, Alae E; Voegel, Jean-Claude; Senger, Bernard; Schaaf, Pierre; Frisch, Benoît; Boulmedais, Fouzia

    2010-02-16

    We report the covalent layer-by-layer construction of polyelectrolyte multilayer (PEM) films by using an efficient electrochemically triggered Sharpless click reaction. The click reaction is catalyzed by Cu(I) which is generated in situ from Cu(II) (originating from the dissolution of CuSO(4)) at the electrode constituting the substrate of the film. The film buildup can be controlled by the application of a mild potential inducing the reduction of Cu(II) to Cu(I) in the absence of any reducing agent or any ligand. The experiments were carried out in an electrochemical quartz crystal microbalance cell which allows both to apply a controlled potential on a gold electrode and to follow the mass deposited on the electrode through the quartz crystal microbalance. Poly(acrylic acid) (PAA) modified with either alkyne (PAA(Alk)) or azide (PAA(Az)) functions grafted onto the PAA backbone through ethylene glycol arms were used to build the PEM films. Construction takes place on gold electrodes whose potentials are more negative than a critical value, which lies between -70 and -150 mV vs Ag/AgCl (KCl sat.) reference electrode. The film thickness increment per bilayer appears independent of the applied voltage as long as it is more negative than the critical potential, but it depends upon Cu(II) and polyelectrolyte concentrations in solution and upon the reduction time of Cu(II) during each deposition step. An increase of any of these latter parameters leads to an increase of the mass deposited per layer. For given buildup conditions, the construction levels off after a given number of deposition steps which increases with the Cu(II) concentration and/or the Cu(II) reduction time. A model based on the diffusion of Cu(II) and Cu(I) ions through the film and the dynamics of the polyelectrolyte anchoring on the film, during the reduction period of Cu(II), is proposed to explain the major buildup features.

  3. Ruthenium-Catalyzed Ammonia Borane Dehydrogenation: Mechanism and Utility.

    Science.gov (United States)

    Zhang, Xingyue; Kam, Lisa; Trerise, Ryan; Williams, Travis J

    2017-01-17

    One of the greatest challenges in using H2 as a fuel source is finding a safe, efficient, and inexpensive method for its storage. Ammonia borane (AB) is a solid hydrogen storage material that has garnered attention for its high hydrogen weight density (19.6 wt %) and ease of handling and transport. Hydrogen release from ammonia borane is mediated by either hydrolysis, thus giving borate products that are difficult to rereduce, or direct dehydrogenation. Catalytic AB dehydrogenation has thus been a popular topic in recent years, motivated both by applications in hydrogen storage and main group synthetic chemistry. This Account is a complete description of work from our laboratory in ruthenium-catalyzed ammonia borane dehydrogenation over the last 6 years, beginning with the Shvo catalyst and resulting ultimately in the development of optimized, leading catalysts for efficient hydrogen release. We have studied AB dehydrogenation with Shvo's catalyst extensively and generated a detailed understanding of the role that borazine, a dehydrogenation product, plays in the reaction: it is a poison for both Shvo's catalyst and PEM fuel cells. Through independent syntheses of Shvo derivatives, we found a protective mechanism wherein catalyst deactivation by borazine is prevented by coordination of a ligand that might otherwise be a catalytic poison. These studies showed how a bidentate N-N ligand can transform the Shvo into a more reactive species for AB dehydrogenation that minimizes accumulation of borazine. Simultaneously, we designed novel ruthenium catalysts that contain a Lewis acidic boron to replace the Shvo -OH proton, thus offering more flexibility to optimize hydrogen release and take on more general problems in hydride abstraction. Our scorpionate-ligated ruthenium species (12) is a best-of-class catalyst for homogeneous dehydrogenation of ammonia borane in terms of its extent of hydrogen release (4.6 wt %), air tolerance, and reusability. Moreover, a synthetically

  4. Captan impairs CYP-catalyzed drug metabolism in the mouse.

    Science.gov (United States)

    Paolini, M; Barillari, J; Trespidi, S; Valgimigli, L; Pedulli, G F; Cantelli-Forti, G

    1999-11-30

    To investigate whether the fungicide captan impairs CYP-catalyzed drug metabolism in murine liver, kidney and lung, the modulation of the regio- and stereo-selective hydroxylation of testosterone, including 6beta-(CYP3A), 6alpha-(CYP2A1 and CYP2B1) and 16alpha-(CYP2B9) oxidations was studied. Specific substrates as probes for different CYP isoforms such as p-nitrophenol (CYP2E1), pentoxyresorufin (CYP2B1), ethoxyresorufin (CYP1A1), aminopyrine (CYP3A), phenacetin and methoxyresorufin (CYP1A2), and ethoxycoumarin (mixed) were also considered. Daily doses of captan (7.5 or 15 mg/kg b.w., i.p.) were administered to different groups of Swiss Albino CD1 mice of both sexes for 1 or 3 consecutive days. While a single dose of this fungicide did not affect CYP-machinery, repeated treatment significantly impaired the microsomal metabolism; in the liver, for example, a general inactivating effect was observed, with the sole exception of testosterone 2alpha-hydroxylase activity which was induced up to 8.6-fold in males. In vitro studies showed that the mechanism-based inhibition was related to captan metabolites rather than the parental compound. In the kidney, both CYP3A- and CYP1A2-linked monooxygenases were significantly induced (2-fold) by this pesticide. Accelerated phenacetin and methoxyresorufin metabolism (CYP1A2) was also observed in the lung. Data on CYP3A (kidney) and CYP1A2 (kidney and lung) induction were corroborated by Western immunoblotting using rabbit polyclonal anti-CYP3A1/2 and CYP1A1/2 antibodies. By means of electron spin resonance (EPR) spectrometry coupled to a spin-trapping technique, it was found that the recorded induction generates a large amounts of the anion radical superoxide (O*2-) either in kidney or lung microsomes. These findings suggest that alterations in CYP-associated activities by captan exposure may result in impaired (endogenous) metabolism as well as of coadministered drugs with significant implications for their disposition. The

  5. Ru(ii)-Catalyzed C-H activation and annulation of salicylaldehydes with monosubstituted and disubstituted alkynes.

    Science.gov (United States)

    Baruah, Swagata; Kaishap, Partha Pratim; Gogoi, Sanjib

    2016-10-27

    The Ru(ii)-catalyzed C-H activation and annulation reaction of salicylaldehydes and disubstituted alkynes affords chromones in high yields. This reaction also works with terminal alkynes and tolerates a wide range of sensitive functional groups. The selectivity pattern of this Ru(ii)-catalyzed annulation reaction is different from the known Au(i), Rh(iii)-catalyzed annulation reactions of salicylaldehydes and terminal alkynes.

  6. Enzyme-catalyzed reaction of voltammetric enzyme-linked immunoassay system based on OAP as substrate

    Institute of Scientific and Technical Information of China (English)

    张书圣; 陈洪渊; 焦奎

    1999-01-01

    The o-aminophenol (OAP)-H2O2-horseradish peroxidase (HRP) voltammetric enzyme-linked immunoassay new system has extremely high sensitivity. HRP can be measured with a detection limit of 6.0×10-(10) g/L and a linear range of 1.0×10-9—4.0×10-6 g/L. The pure product of H2O2 oxidizing OAP catalyzed by HRP was prepared with chemical method. The enzyme-catalyzed reaction has been investigated with electroanalytical chemistry, UV/Vis spectrum, IR spectrum, 13C NMR, 1H NMR, mass spectrum, elemental analysis, etc. Under the selected enzyme-catalyzed reaction conditions, the oxidation product of OAP with H2O2 catalyzed by HRP is 2-aminophe-noxazine-3-one. The processes of the enzyme-catalyzed reaction and the electroreduction of the product of the enzymecatalyzed reaction have been described.

  7. [Degradation of nitrobenzene in aqueous solution by modified ceramic honeycomb-catalyzed ozonation].

    Science.gov (United States)

    Sun, Zhi-Zhong; Zhao, Lei; Ma, Jun

    2005-11-01

    Comparative experiments of modified ceramic honeycomb, ceramic honeycomb-catalyzed ozonation and ozonation alone were conducted with nitrobenzene as the model organic pollutant. It was found that the processes of modified ceramic honeycomb and ceramic honeycomb-catalyzed ozonation could increase the removal efficiency of nitrobenzene by 38.35% and 15.46%, respectively, compared with that achieved by ozonation alone. Under the conditions of this experiment, the degradation rate of modified ceramic honeycomb-catalyzed ozonation increased by 30.55% with the increase of amount of catalyst to 5 blocks. The degradation rate of three process all increased greatly with the increase of temperature and value of pH in the solution. But when raising the pH value of the solution to 10.00, the advantage of modified ceramic honeycomb-catalyzed ozonation processes lost. The experimental results indicate that in modified ceramic honeycomb-catalyzed ozonation, nitrobenzene is primarily oxidized by *OH free radical in aqueous solution. The adsorption of nitrobenzene is too limited to have any influence on the degradation efficiency of nitrobenzene. With the same total dosage of applied ozone, the multiple steps addition of ozone showed a much higher removal efficiency than that obtained by one step in three processes. Modified ceramic honeycomb had a relative longer lifetime.

  8. Nanostructured Ti-catalyzed MgH2 for hydrogen storage

    Science.gov (United States)

    Shao, H.; Felderhoff, M.; Schüth, F.; Weidenthaler, C.

    2011-06-01

    Nanocrystalline Ti-catalyzed MgH2 can be prepared by a homogeneously catalyzed synthesis method. Comprehensive characterization of this sample and measurements of hydrogen storage properties are discussed and compared to a commercial MgH2 sample. The catalyzed MgH2 nanocrystalline sample consists of two MgH2 phases—a tetrahedral β-MgH2 phase and an orthorhombic high-pressure modification γ-MgH2. Transmission electron microscopy was used for the observation of the morphology of the samples and to confirm the nanostructure. N2 adsorption measurement shows a BET surface area of 108 m2 g - 1 of the nanostructured material. This sample exhibits a hydrogen desorption temperature more than 130 °C lower compared to commercial MgH2. After desorption, the catalyzed nanocrystalline sample absorbs hydrogen 40 times faster than commercial MgH2 at 300 °C. Both the Ti catalyst and the nanocrystalline structure with correspondingly high surface area are thought to play important roles in the improvement of hydrogen storage properties. The desorption enthalpy and entropy values of the catalyzed MgH2 nanocrystalline sample are 77.7 kJ mol - 1 H2 and 138.3 J K - 1 mol - 1 H2, respectively. Thermodynamic properties do not change with the nanostructure.

  9. Removal of SU-8 resists using hydrogen radicals generated by tungsten hot-wire catalyzer

    Science.gov (United States)

    Kono, Akihiko; Arai, Yu; Goto, Yousuke; Horibe, Hideo

    2012-03-01

    We investigated removal of chemically amplified negative-tone i-line resist SU-8 using hydrogen radicals, which was generated by the catalytic decomposition of H2/N2 mixed gas (H2:N2 = 10:90vol.%) using tungsten hot-wire catalyzer. SU-8 with exposure dose from 7 (Dg100×0.5) to 280mJ/cm2 (Dg100×20) were removed by hydrogen radicals without a residual layer. When the distance between the catalyzer and the substrate was 100mm, the catalyzer temperature was 2400°C, and the initial substrate temperature was 50°C, removal rate of SU-8 was 0.17μm/min independent of exposure dose to the SU-8. Finally, we obtained high removal rate for SU-8 (exposure dose = 14mJ/cm2 (Dg100)) of approximately 4μm/min when the distance between the catalyzer and the substrate was 20mm, the catalyzer temperature was 2400°C, and the initial substrate temperature was 165°C.

  10. Nanostructured Ti-catalyzed MgH2 for hydrogen storage.

    Science.gov (United States)

    Shao, H; Felderhoff, M; Schüth, F; Weidenthaler, C

    2011-06-10

    Nanocrystalline Ti-catalyzed MgH(2) can be prepared by a homogeneously catalyzed synthesis method. Comprehensive characterization of this sample and measurements of hydrogen storage properties are discussed and compared to a commercial MgH(2) sample. The catalyzed MgH(2) nanocrystalline sample consists of two MgH(2) phases-a tetrahedral β-MgH(2) phase and an orthorhombic high-pressure modification γ-MgH(2). Transmission electron microscopy was used for the observation of the morphology of the samples and to confirm the nanostructure. N(2) adsorption measurement shows a BET surface area of 108 m(2) g(-1) of the nanostructured material. This sample exhibits a hydrogen desorption temperature more than 130 °C lower compared to commercial MgH(2). After desorption, the catalyzed nanocrystalline sample absorbs hydrogen 40 times faster than commercial MgH(2) at 300 °C. Both the Ti catalyst and the nanocrystalline structure with correspondingly high surface area are thought to play important roles in the improvement of hydrogen storage properties. The desorption enthalpy and entropy values of the catalyzed MgH(2) nanocrystalline sample are 77.7 kJ mol(-1) H(2) and 138.3 J K(-1) mol(-1) H(2), respectively. Thermodynamic properties do not change with the nanostructure.

  11. Iridium and ruthenium catalyzed syntheses, hydroborations, and metathesis reactions of alkenyl-decaboranes.

    Science.gov (United States)

    Chatterjee, Shahana; Carroll, Patrick J; Sneddon, Larry G

    2013-08-05

    The selective syntheses of new classes of 6,9-dialkenyl- and 6-alkenyl-decaboranes and 6-alkyl-9-alkenyl-decaboranes have been achieved via iridium and ruthenium catalyzed decaborane and 6-alkyl-decaborane alkyne-hydroborations. Reactions employing [Cp*IrCl2]2 and [RuCl2(p-cymene)]2 precatalysts gave β-E-alkenyl-decaboranes, while the corresponding reactions with [RuI2(p-cymene)]2 gave the α-alkenyl-decaborane isomers, with the differences in product selectivity suggesting quite different mechanistic steps for the catalysts. The alkenyl-decaboranes were easily converted to other useful derivatives, including coupled-cage and functionally substituted compounds, via iridium-catalyzed hydroborations and ruthenium-catalyzed homo and cross olefin-metathesis reactions.

  12. Horseradish peroxidase catalyzed free radical cannot free move in reaction solution

    Directory of Open Access Journals (Sweden)

    Cai Xialing

    2009-08-01

    Full Text Available Mechanism of Horseradish Peroxidase -catalyzed phenol compound oxidizing reaction is a radical polymerization. Many polymer preparation are also carry on through the radical polymerization mechanism We deduce if free radical produced by peroxidasecatalyzed phenol polymerization could apply on polymer preparation? Could the phenol–oxygen free radical leave off the peroxidase and catalyze other compounds polymerization? The free radical in phenol oxidation process was investigated in homogeneous reaction and in immobilized HRP catalyzed reaction. The results showed the free radical produced by peroxidase only move on the surface of enzyme, can’t free move in solution in both experiment. Evidence showed the phenol polymerization is enzyme reaction process, different from general chemistry free radical chain reaction.Keywords: Horseradish Peroxidase, free radical polymerization, mechanismReceived: 17 March 2008 / Received in revised form: 5 February 2009, Accepted: 31 April 2009 Published online: 14 May 2009

  13. Polymerization of o-Phenylenediamine Catalyzed by Hemeproteins Encapsulated in Reversed Micelle

    Institute of Scientific and Technical Information of China (English)

    YANG Yong; MAO Lu-yuan; LI Liu-zhu; LIU Xiao-guang; SHI Jun; CAO Shao-kui

    2004-01-01

    Hemeproteins encapsulated in reversed micelle formulated with di-2-ethylhexyl sulfosuccinate (AOT)was found to catalyze the polymerization of o-phenylenediamine (o-PDA) with hydrogen peroxide, whereas o-PDA catalyzed by hemeproteins dissolved in water could only form its trimers. As the nanostructural environment in reversed micelle acts as a certain orientation surrounding medium, it offers a strong electrostatic field that alters the reductive potential of Fe3+/Fe2+ (Em7) in the heme of hemeproteins and thus increases the catalytic activity of peroxidase accordingly. According to the results of UV-Vis, 1H NMR and FTIR, the polymer catalyzed by hemoglobin(Hb) in reversed micelle was presumed to be constructed of lines and trapeziforms alternatively.

  14. First Novozym 435 lipase-catalyzed Morita-Baylis-Hillman reaction in the presence of amides.

    Science.gov (United States)

    Tian, Xuemei; Zhang, Suoqin; Zheng, Liangyu

    2016-03-01

    The first Novozym 435 lipase-catalyzed Morita-Baylis-Hillman (MBH) reaction with amides as co-catalyst was realized. Results showed that neither Novozym 435 nor amide can independently catalyze the reaction. This co-catalytic system that used a catalytic amount of Novozym 435 with a corresponding amount of amide was established and optimized. The MBH reaction strongly depended on the structure of aldehyde substrate, amide co-catalyst, and reaction additives. The optimized reaction yield (43.4%) was achieved in the Novozym 435-catalyzed MBH reaction of 2, 4-dinitrobenzaldehyde and cyclohexenone with isonicotinamide as co-catalyst and β-cyclodextrin as additive only in 2 days. Although enantioselectivity of Novozym 435 was not found, the results were still significant because an MBH reaction using lipase as biocatalyst was realized for the first time.

  15. Brønsted Acid-Catalyzed Direct Substitution of 2-Ethoxytetrahydrofuran with Trifluoroborate Salts

    Directory of Open Access Journals (Sweden)

    Kayla M. Fisher

    2016-06-01

    Full Text Available Metal-free transformations of organotrifluoroborates are advantageous since they avoid the use of frequently expensive and sensitive transition metals. Lewis acid-catalyzed reactions involving potassium trifluoroborate salts have emerged as an alternative to metal-catalyzed protocols. However, the drawbacks to these methods are that they rely on the generation of unstable boron dihalide species, thereby resulting in low functional group tolerance. Recently, we discovered that in the presence of a Brønsted acid, trifluoroborate salts react rapidly with in situ generated oxocarbenium ions. Here, we report Brønsted acid-catalyzed direct substitution of 2-ethoxytetrahydrofuran using potassium trifluoroborate salts. The reaction occurs when tetrafluoroboric acid is used as a catalyst to afford functionalized furans in moderate to excellent yields. A variety of alkenyl- and alkynyltrifluoroborate salts readily participate in this transformation.

  16. Theoretical Studies on the Iodine-catalyzed Nucleophilic Addition of Acetone with Five-membered Heterocycles

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-hua; LI Li; CHEN Xue-song

    2008-01-01

    The iodine-catalyzed nucleophilic addition reactions of pyrrole,furan,or thiophene with acetone were studied in gas and solvent by the density functional theory at the level of Lan12DZ*,It was seen that the halogen bond between iodine and carbonyl oxygen appeared to have an important catalytic effect on such reactions,and the first iodine molecule maximally diminished the barrier height by 41 kJ/mol,while the second iodine molecule could not improve such reactions largely,It was concluded that the C2-addition was generally more favorable than the C3-addition for the three heterocycles;however,iodine considerably more effectively catalyzed the C3-addition than the C2-addition for pyrrole,It was also revealed by PCM calculation that the iodine-catalyzed nucleophilic additions occurred more easily in solvent than in gas,which explained the experiment performed by Bandgar et al..

  17. Heterogeneous oxidation of cyclohexanone catalyzed by TS-1:Combined experimental and DFT studies

    Institute of Scientific and Technical Information of China (English)

    Changjiu Xia; Xingtian Shu; Long Ju; Yi Zhao; Hongyi Xu; Bin Zhu; Feifei Gao; Min Lin; Zhenyu Dai; Xiaodong Zou

    2015-01-01

    The reaction mechanism of the oxidation of cyclohexanone catalyzed by titanium silicate zeolite TS-1 using aqueous H2O2 as the oxidant was investigated by combining density function theory (DFT) calculations with experimental studies. DFT calculations showed that H2O2 was adsorbed and activated at the tetrahedral Ti sites. By taking into account the adsorption energy, molecular size, steric hindrance and structural information, a reaction mechanism of Baeyer-Villiger oxidation catalyzed by TS-1 that involves the activation of H2O2 was proposed. Experimental studies showed that the major products of cyclohexanone oxidation by H2O2 catalyzed by a hollow TS-1 zeolite wereε-carprolactone, 6-hydroxyhexanoic acid, and adipic acid. These products were analyzed by GC-MS and were in good agreement with the proposed mechanism. Our studies showed that the reaction mechanism on TS-1 zeolite was different from that on Sn-beta zeolite.

  18. Investigation of the effect of organic solvents on kinetic parameters in metal catalyzed reactions

    Directory of Open Access Journals (Sweden)

    GORDANA A. MILOVANOVIC

    2000-03-01

    Full Text Available The effects of acetone and acetonitrile on the kinetic parameters of azorubin S oxidation by hydrogen peroxide catalyzed by manganese(II, pyrocatechol violet oxidation by hydrogen peroxide catalyzed by copper(II, and carminic acid oxidation by hydrogen peroxide catalyzed by copper(II and activated by bifenox, were examined. It was established that the examined solvents exhibit various effects on the kinetic parameters of the above said reactions. In a11 instances a change in the solvent concentration effects both the anthalpy and the entropy contributions to the free activation energy during the transition of the system into the active state, as well as the constant of the active complex formed at this point.

  19. Catalyzing Transdisciplinarity: A Systems Ethnography of Cancer-Obesity Comorbidity and Risk Coincidence.

    Science.gov (United States)

    Graham, S Scott; Harley, Amy; Kessler, Molly M; Roberts, Laura; DeVasto, Dannielle; Card, Daniel J; Neuner, Joan M; Kim, Sang-Yeon

    2017-05-01

    Effectively addressing wicked health problems, that is, those arising from complex multifactorial biological and socio-economic causes, requires transdisciplinary action. However, a significant body of research points toward substantial difficulties in cultivating transdisciplinary collaboration. Accordingly, this article presents the results of a study that adapts Systems Ethnography and Qualitative Modeling (SEQM) in response to wicked health problems. SEQM protocols were designed to catalyze transdisciplinary responses to national defense concerns. We adapted these protocols to address cancer-obesity comorbidity and risk coincidence. In so doing, we conducted participant-observations and interviews with a diverse range of health care providers, community health educators, and health advocacy professionals who target either cancer or obesity. We then convened a transdisciplinary conference designed to catalyze a coordinated response. The findings offer productive insights into effective ways of catalyzing transdisciplinarity in addressing wicked health problems action and demonstrate the promise of SEQM for continued use in health care contexts.

  20. Iron-Catalyzed C-C Cross-Couplings Using Organometallics.

    Science.gov (United States)

    Guérinot, Amandine; Cossy, Janine

    2016-08-01

    Over the last decades, iron-catalyzed cross-couplings have emerged as an important tool for the formation of C-C bonds. A wide variety of alkenyl, aryl, and alkyl (pseudo)halides have been coupled to organometallic reagents, the most currently used being Grignard reagents. Particular attention has been devoted to the development of iron catalysts for the functionalization of alkyl halides that are generally challenging substrates in classical cross-couplings. The high functional group tolerance of iron-catalyzed cross-couplings has encouraged organic chemists to use them in the synthesis of bioactive compounds. Even if some points remain obscure, numerous studies have been carried out to investigate the mechanism of iron-catalyzed cross-coupling and several hypotheses have been proposed.

  1. Constitutive modeling of the viscoelastic and viscoplastic responses of metallocene catalyzed polypropylene

    DEFF Research Database (Denmark)

    Drozdov, Aleksey; Christiansen, Jesper de Claville; Sanporean, Catalina-Gabriela

    2012-01-01

    Purpose – The purpose of this paper is to perform experimental investigation and constitutive modeling of the viscoelastic and viscoplastic behavior of metallocene catalyzed polypropylene (mPP) with application to lifetime assessment under conditions of creep rupture. Design/methodology/approach ...... in long-term creep tests. Keywords Metallocene catalyzed polypropylene, Viscoelasticity, Viscoplasticity, Creep rupture, Constitutive modeling, Elastoplastic analysis, Viscosity, Creep, Physical properties of materials Paper type Research paper....../methodology/approach – Three series of experiments are conducted where the mechanical response of mPP is analyzed in tensile tests with various strain rates, relaxation tests with various strains, and creep tests with various stresses at room temperature. A constitutive model is derived for semicrystalline polymers under......Purpose – The purpose of this paper is to perform experimental investigation and constitutive modeling of the viscoelastic and viscoplastic behavior of metallocene catalyzed polypropylene (mPP) with application to lifetime assessment under conditions of creep rupture. Design...

  2. Enzyme catalyzed oxidative cross-linking of feruloylated pectic polysaccharides from sugar beet

    DEFF Research Database (Denmark)

    Abang Zaidel, Dayang Norulfairuz

    -linking and consequently the properties of the gels formed. The kinetics of oxidative gelation of SBP, taking place via enzyme catalyzed cross-linking of FA, was evaluated by small angle oscillatory measurements. The result indicates a significant difference between the SBP gels produced from the catalysis of HRP...... and laccase, that is, laccase catalysis produced stronger SBP gels albeit slower rates of gelation than the HRP catalysis. Statistically design experiment has been constructed to investigate the effect of several reaction factors which might influence the rates of gelation of SBP catalyzed by HRP or laccase......, particularly the pectin level, temperature, enzyme dosage, pH and, for HRP, the H2O2 concentration. The result reveals that these reaction factors could be tuned in order to adjust the enzyme catalyzed gelation and the properties of the gels produced. Moreover, positive correlation between the rates...

  3. Using simple donors to drive the equilibria of glycosyltransferase-catalyzed reactions.

    Science.gov (United States)

    Gantt, Richard W; Peltier-Pain, Pauline; Cournoyer, William J; Thorson, Jon S

    2011-08-21

    We report that simple glycoside donors can drastically shift the equilibria of glycosyltransferase-catalyzed reactions, transforming NDP-sugar formation from an endothermic to an exothermic process. To demonstrate the utility of this thermodynamic adaptability, we highlight the glycosyltransferase-catalyzed synthesis of 22 sugar nucleotides from simple aromatic sugar donors, as well as the corresponding in situ formation of sugar nucleotides as a driving force in the context of glycosyltransferase-catalyzed reactions for small-molecule glycodiversification. These simple aromatic donors also enabled a general colorimetric assay for glycosyltransfer, applicable to drug discovery, protein engineering and other fundamental sugar nucleotide-dependent investigations. This study directly challenges the general notion that NDP-sugars are 'high-energy' sugar donors when taken out of their traditional biological context.

  4. Rhodium-catalyzed acyloxy migration of propargylic esters in cycloadditions, inspiration from the recent "gold rush".

    Science.gov (United States)

    Shu, Xing-Zhong; Shu, Dongxu; Schienebeck, Casi M; Tang, Weiping

    2012-12-07

    Transition metal-catalyzed acyloxy migration of propargylic esters offers versatile entries to allene and vinyl carbene intermediates for various fascinating subsequent transformations. Most π-acidic metals (e.g. gold and platinum) are capable of facilitating these acyloxy migration events. However, very few of these processes involve redox chemistry, which are well-known for most other transition metals such as rhodium. The coupling of acyloxy migration of propargylic esters with oxidative addition, migratory insertion, and reductive elimination may lead to ample new opportunities for the design of new reactions. This tutorial review summarizes recent developments in Rh-catalyzed 1,3- and 1,2-acyloxy migration of propargylic esters in a number of cycloaddition reactions. Related Au- and Pt-catalyzed cycloadditions involving acyloxy migration are also discussed.

  5. Carbon dioxide reduction to methane and coupling with acetylene to form propylene catalyzed by remodeled nitrogenase.

    Science.gov (United States)

    Yang, Zhi-Yong; Moure, Vivian R; Dean, Dennis R; Seefeldt, Lance C

    2012-11-27

    A doubly substituted form of the nitrogenase MoFe protein (α-70(Val)(→Ala), α-195(His→Gln)) has the capacity to catalyze the reduction of carbon dioxide (CO(2)) to yield methane (CH(4)). Under optimized conditions, 1 nmol of the substituted MoFe protein catalyzes the formation of 21 nmol of CH(4) within 20 min. The catalytic rate depends on the partial pressure of CO(2) (or concentration of HCO(3)(-)) and the electron flux through nitrogenase. The doubly substituted MoFe protein also has the capacity to catalyze the unprecedented formation of propylene (H(2)C = CH-CH(3)) through the reductive coupling of CO(2) and acetylene (HC≡CH). In light of these observations, we suggest that an emerging understanding of the mechanistic features of nitrogenase could be relevant to the design of synthetic catalysts for CO(2) sequestration and formation of olefins.

  6. Dechlorination of carbon tetrachloride by the catalyzed Fe-Cu process

    Institute of Scientific and Technical Information of China (English)

    XU Wen-ying; GAO Ting-yao

    2007-01-01

    The electrochemical reduction characteristics of carbon tetrachloride (CT) were investigated using cyclic voltammetry in this study. In addition, the difference in reduction mechanisms of CT between Master Builders' iron and the catalyzed Fe-Cu process was discussed. The results showed that CT was reduced directly on the surface of copper rather than by atomic hydrogen produced at the cathode in the catalyzed Fe-Cu process. The reduction was realized largely by atomic hydrogen in Master Builders' iron. The entire CT in 350 ml aqueous solution with 320 mg/L was reduced to trichloromethane and dichloromethane in 2.25 h when 100 g of scrap iron with Fe/Cu ratio of 10:1 (w/w) were used. Moreover, the reduction rate slowed with time. CT could be reduced at acidic, neutral and alkaline pH from solution by Fe-Cu bimetallic media, but the mechanisms were different. The degradation rate was not significantly influenced by pH in the catalyzed Fe-Cu process; in Master Builders' iron it clearly increased with decreasing pH. The kinetics of the reductions followed pseudo-first order in both cases. Furthermore, the reductions under acidic conditions proceeded faster than that under the neutral and alkaline conditions. The catalyzed Fe-Cu process was superior to Master Builders' iron in treating CT-containing water and this advantage was particularly noticeable under alkaline conditions. The reduction was investigated in the cathode (Cu) and anode (Fe) compartments respectively, the results showed that the direct reduction pathway played an important role in the reduction by the catalyzed Fe-Cu process. The catalyzed Fe-Cu process is of practical value.

  7. Kinetic Behavior of Aggregation-Exchange Growth Process with Catalyzed-Birth

    Institute of Scientific and Technical Information of China (English)

    HAN An-Jia; CHEN Yu; LIN Zhen-Quan; KE Jian-Hong

    2007-01-01

    We propose an aggregation model of a two-species system to mimic the growth of cities' population and assets,in which irreversible coagulation reactions and exchange reactions occur between any two aggregates of the same species,and the monomer-birth reactions of one species occur by the catalysis of the other species.In the case with population-catalyzed birth of assets,the rate kernel of an asset aggregate Bκ of size k grows to become an aggregate Bκ+ 1through a monomer-birth catalyzed by a population aggregate Aj of size j is J(k,j) = Jkjλ.And in mutually catalyzed birth model,the birth rate kernels of population and assets are H(k,j) = Hkjη and J(k,j) = Jkjλ,respectively.The kinetics of the system is investigated based on the mean-field theory.In the model of population-catalyzed birth of assets,the long-time asymptotic behavior of the assets aggregate size distribution obeys the conventional or modified scaling form.In mutually catalyzed birth system,the asymptotic behaviors of population and assets obey the conventional scaling form in the case ofη =λ= 0,and they obey the modified scalingform in the case of η = 0,λ= 1.In the case of η = λ = 1,the total mass of population aggregates and that of asset aggregates both grow much faster than those in population-catalyzed birth of assets model,and they approaches to infinite values in finite time.

  8. Biofuel-Promoted Polychlorinated Dibenzodioxin/furan Formation in an Iron-Catalyzed Diesel Particle Filter.

    Science.gov (United States)

    Heeb, Norbert V; Rey, Maria Dolores; Zennegg, Markus; Haag, Regula; Wichser, Adrian; Schmid, Peter; Seiler, Cornelia; Honegger, Peter; Zeyer, Kerstin; Mohn, Joachim; Bürki, Samuel; Zimmerli, Yan; Czerwinski, Jan; Mayer, Andreas

    2015-08-04

    Iron-catalyzed diesel particle filters (DPFs) are widely used for particle abatement. Active catalyst particles, so-called fuel-borne catalysts (FBCs), are formed in situ, in the engine, when combusting precursors, which were premixed with the fuel. The obtained iron oxide particles catalyze soot oxidation in filters. Iron-catalyzed DPFs are considered as safe with respect to their potential to form polychlorinated dibenzodioxins/furans (PCDD/Fs). We reported that a bimetallic potassium/iron FBC supported an intense PCDD/F formation in a DPF. Here, we discuss the impact of fatty acid methyl ester (FAME) biofuel on PCDD/F emissions. The iron-catalyzed DPF indeed supported a PCDD/F formation with biofuel but remained inactive with petroleum-derived diesel fuel. PCDD/F emissions (I-TEQ) increased 23-fold when comparing biofuel and diesel data. Emissions of 2,3,7,8-TCDD, the most toxic congener [toxicity equivalence factor (TEF) = 1.0], increased 90-fold, and those of 2,3,7,8-TCDF (TEF = 0.1) increased 170-fold. Congener patterns also changed, indicating a preferential formation of tetra- and penta-chlorodibenzofurans. Thus, an inactive iron-catalyzed DPF becomes active, supporting a PCDD/F formation, when operated with biofuel containing impurities of potassium. Alkali metals are inherent constituents of biofuels. According to the current European Union (EU) legislation, levels of 5 μg/g are accepted. We conclude that risks for a secondary PCDD/F formation in iron-catalyzed DPFs increase when combusting potassium-containing biofuels.

  9. Synthesis of Fused Dibenzofuran Derivatives via Palladium-Catalyzed Domino C-C Bond Formation and Iron-Catalyzed Cycloisomerization/Aromatization.

    Science.gov (United States)

    Paul, Kartick; Jalal, Swapnadeep; Kundal, Sandip; Jana, Umasish

    2016-02-05

    A range of tetracyclic dibenzofuran derivatives bearing a variety of functional groups was readily synthesized via a two-stage domino strategy starting from propargyl ethers of 2-halo phenol derivatives. The first stage in the strategy involves Pd(0)-catalyzed domino intramolecular carbopalladation/Suzuki coupling via 5-exo-dig cyclization onto the alkyne, leading to 3-methylene-2,3-dihydrobenzofuran derivatives. In the second stage of the domino strategy, an iron(III)-catalyzed cycloisomerization and aromatization reaction produces tetracyclic benzofuran derivatives. This two-step sequence provides efficient access to diversely substituted polycyclic dibenzofuran derivatives in high yields and in an atom-efficient and environmentally friendly manner. Moreover, this strategy was also successfully used for the synthesis of a naturally occurring tetracyclic dibenzofuran, β-brazan.

  10. Acid-catalyzed hydrogenation of olefins. A theoretical study of the HF- and H/sub 3/O/sup +/-catalyzed hydrogenation of ethylene

    Energy Technology Data Exchange (ETDEWEB)

    Siria, J.C.; Duran, M.; Lledos, A.; Bertran, J.

    1987-12-09

    The HF- and H/sub 3/O/sup +/-catalyzed hydrogenation of ethylene and the direct addition of molecular hydrogen to ethylene have been studied theoretically by means of ab initio MO calculations using different levels of theory. The main results are that catalysis by HF lowers the potential energy barrier to a large extent, while catalysis by H/sub 3/O/sup +/ diminishes dramatically the barrier for the reaction. Entropic contributions leave these results unchanged. The mechanisms of the two acid-catalyzed hydrogenations are somewhat different. While catalysis by HF exhibits bifunctional characteristics, catalysis by H/sub 3/O/sup +/ proceeds via an initial formation of a carbocation. It is shown that catalysis by strong acids may be an alternate way for olefin hydrogenation.

  11. Effect of coconut oil and soybean oil ethoxylates on peroxidation of liver tissue lipid of mice%椰子油和大豆油的乙氧基化物对小鼠肝脏的脂质过氧化效应研究

    Institute of Scientific and Technical Information of China (English)

    罗毅; 李瑞金; 孙永强; HRECZUCH Wieslaw

    2012-01-01

    In order to investigate effects of coconut oil ethoxylates (COE -36) and soybean oil ethoxylates (SOE -42) on peroxidation of liver tissue lipid of mice,activity of superoxide dismutase (SOD) and catalase (CAT) as well as amount of malonaldehyde ( MDA) formed in liver of mice of COE -36 treatment group, SOE -42 treatment group,cadmium chloride treatment (positive control test) group (2. 5 μg · g-1 based upon mass of mice) and physiological saline treatment (negative control test) group were tested and measured respectively via intraperitoneal injection technology. The results showed that cadmium chloride significantly inhibits the three indices (activity of SOD and CAT and amount of MDA formed in mice liver) as compared with that of saline treatment group. The changes of the three indices in mice liver of COE - 36 treatment groups as well as SOE - 42 treatment groups with three different dosage levels are not significant as compared with that of saline treatment group. The changes of SOD and CAT activity in COE - 36 treatment groups with three different dosage levels, the change of CAT activity in SOE - 42 treatment groups with three different dosage levels and the change of MDA formed in mice liver of COE - 36 and SOE - 42 treatment groups with low dosage (3 mg · g-1 COE -36 and SOE -42 respectively) are significant as compared with that of cadmium chloride treatment group. The observations suggested that COE - 36 or SOE - 42 in the tested dosages (3 -5 mg · g-1) would not induce peroxidation in lipid of mice liver tissues.%为探讨椰子油乙氧基化物- 36EO(COE - 36)和大豆油乙氧基化物- 42EO(SOE - 42)对小鼠肝脏的脂质过氧化作用,采用腹腔注射技术,测定COE - 36处理组、SOE - 42处理组、氯化镉阳性对照组(小鼠单位体质量的氯化镉用量为2.5 μg·g-1)和生理盐水阴性对照组小鼠肝脏超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性和丙二醛(MDA)生成量.结果表明,氯化镉显著抑制

  12. Metal-catalyzed decaborane-alkyne hydroboration reactions: efficient routes to alkenyldecaboranes.

    Science.gov (United States)

    Chatterjee, Shahana; Carroll, Patrick J; Sneddon, Larry G

    2010-04-05

    Transition-metal-catalyzed decaborane-alkyne hydroboration reactions have been developed that provide high-yield routes to the previously unknown di- and monoalkenyldecaboranes. These alkenyl derivatives should be easily modified starting materials for many biomedical and/or materials applications. Unusual catalyst product selectivity was observed that suggests quite different mechanistic steps, with the reactions catalyzed by the [RuCl(2)(p-cymene)](2) and [Cp*IrCl(2)](2) complexes giving the beta-E alkenyldecaboranes and the corresponding reactions with the [RuI(2)(p-cymene)](2) complex giving the alpha-alkenyldecaborane isomers.

  13. Rh(III)-Catalyzed meta-C-H Olefination Directed by a Nitrile Template.

    Science.gov (United States)

    Xu, Hua-Jin; Lu, Yi; Farmer, Marcus E; Wang, Huai-Wei; Zhao, Dan; Kang, Yan-Shang; Sun, Wei-Yin; Yu, Jin-Quan

    2017-02-15

    A range of Rh(III)-catalyzed ortho-C-H functionalizations have been developed; however, extension of this reactivity to remote C-H functionalizations through large-ring rhodacyclic intermediates has yet to be demonstrated. Herein we report the first example of the use of a U-shaped nitrile template to direct Rh(III)-catalyzed remote meta-C-H activation via a postulated 12-membered macrocyclic intermediate. Because the ligands used for Rh(III) catalysts are significantly different from those of Pd(II) catalysts, this offers new opportunities for future development of ligand-promoted meta-C-H activation reactions.

  14. Cu-catalyzed trifluoromethylation of aryl iodides with trifluoromethylzinc reagent prepared in situ from trifluoromethyl iodide

    Directory of Open Access Journals (Sweden)

    Yuzo Nakamura

    2013-11-01

    Full Text Available The trifluoromethylation of aryl iodides catalyzed by copper(I salt with trifluoromethylzinc reagent prepared in situ from trifluoromethyl iodide and Zn dust was accomplished. The catalytic reactions proceeded under mild reaction conditions, providing the corresponding aromatic trifluoromethylated products in moderate to high yields. The advantage of this method is that additives such as metal fluoride (MF, which are indispensable to activate silyl groups for transmetallation in the corresponding reactions catalyzed by copper salt by using the Ruppert–Prakash reagents (CF3SiR3, are not required.

  15. Lipase-catalyzed process for biodiesel production: protein engineering and lipase production.

    Science.gov (United States)

    Hwang, Hyun Tae; Qi, Feng; Yuan, Chongli; Zhao, Xuebing; Ramkrishna, Doraiswami; Liu, Dehua; Varma, Arvind

    2014-04-01

    Biodiesel is an environment-friendly and renewable fuel produced by transesterification of various feedstocks. Although the lipase-catalyzed biodiesel production has many advantages over the conventional alkali catalyzed process, its industrial applications have been limited by high-cost and low-stability of lipase enzymes. This review provides a general overview of the recent advances in lipase engineering, including both protein modification and production. Recent advances in biotechnology such as in protein engineering, recombinant methods and metabolic engineering have been employed but are yet to impact lipase engineering for cost-effective production of biodiesel. A summary of the current challenges and perspectives for potential solutions are also provided.

  16. The mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol

    Institute of Scientific and Technical Information of China (English)

    竹湘锋; 徐新华

    2004-01-01

    Fe (Ⅲ)-catalyzed ozonation yielded better degradation rate and extent of COD (Chemical Oxygen Demand) or oxalic acid as compared with oxidation by ozone alone. Two parameters with strong effects on the efficiency of ozonation are pH of the solution and the catalyst (Fe3+) dosage. The existence of a critical pH value determining the catalysis ofFe (Ⅲ) in acid conditions was observed in phenol and oxalic acid systems. The best efficiency of catalysis was obtained at a moderate concentration of the catalyst. A reasonable mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol was obtained based on the results and literature.

  17. Glycerol Dehydration to Acrolein Catalyzed by ZSM‐5 Zeolite in Supercritical Carbon Dioxide Medium

    Science.gov (United States)

    Zou, Bin; Ren, Shoujie

    2016-01-01

    Abstract Supercritical carbon dioxide (SC‐CO2) has been used for the first time as a reaction medium for the dehydration of glycerol to acrolein catalyzed by a solid acid. Unprecedented catalyst stability over 528 hours of time‐on‐stream was achieved and the rate of coke deposition on the zeolite catalyst was the lowest among extensive previous studies, showing potential for industrial application. Coking pathways in SC‐CO2 were also elucidated for future development. The results have potential implications for other dehydration reactions catalyzed by solid acids. PMID:27796088

  18. Additive-Free Pd-Catalyzed α-Allylation of Imine-Containing Heterocycles.

    Science.gov (United States)

    Kljajic, Marko; Puschnig, Johannes G; Weber, Hansjörg; Breinbauer, Rolf

    2017-01-06

    An additive-free Pd-catalyzed α-allylation of different imino-group-ontaining heterocycles is reported. The activation of α-CH pronucleophiles (pKa (DMSO) > 25) occurs without the addition of strong bases or Lewis acids using only the Pd/Xantphos catalyst system. The reaction scope has been studied for various 5- and 6-membered nitrogen-containing heterocycles (yields up to 96%). Mechanistic investigations suggest an initial allylation of the imine-N followed by a Pd-catalyzed formal aza-Claisen rearrangement.

  19. FeCl3 -Catalyzed Ring-Closing Carbonyl-Olefin Metathesis.

    Science.gov (United States)

    Ma, Lina; Li, Wenjuan; Xi, Hui; Bai, Xiaohui; Ma, Enlu; Yan, Xiaoyu; Li, Zhiping

    2016-08-22

    Exploiting catalytic carbonyl-olefin metathesis is an ongoing challenge in organic synthesis. Reported herein is an FeCl3 -catalyzed ring-closing carbonyl-olefin metathesis. The protocol allows access to a range of carbo-/heterocyclic alkenes with good efficiency and excellent trans diastereoselectivity. The methodology presents one of the rare examples of catalytic ring-closing carbonyl-olefin metathesis. This process is proposed to take place by FeCl3 -catalyzed oxetane formation followed by retro-ring-opening to deliver metathesis products.

  20. ORGANIC CHEMISTRY. Iron-catalyzed intermolecular [2+2] cycloadditions of unactivated alkenes.

    Science.gov (United States)

    Hoyt, Jordan M; Schmidt, Valerie A; Tondreau, Aaron M; Chirik, Paul J

    2015-08-28

    Cycloadditions, such as the [4+2] Diels-Alder reaction to form six-membered rings, are among the most powerful and widely used methods in synthetic chemistry. The analogous [2+2] alkene cycloaddition to synthesize cyclobutanes is kinetically accessible by photochemical methods, but the substrate scope and functional group tolerance are limited. Here, we report iron-catalyzed intermolecular [2+2] cycloaddition of unactivated alkenes and cross cycloaddition of alkenes and dienes as regio- and stereoselective routes to cyclobutanes. Through rational ligand design, development of this base metal-catalyzed method expands the chemical space accessible from abundant hydrocarbon feedstocks.

  1. An alternative approach to aldol reactions: gold-catalyzed formation of boron enolates from alkynes.

    Science.gov (United States)

    Körner, Cindy; Starkov, Pavel; Sheppard, Tom D

    2010-05-05

    A new method for enolate generation via the gold-catalyzed addition of boronic acids to alkynes is reported. The formation of boron enolates from readily accessible ortho-alkynylbenzeneboronic acids proceeds rapidly with 2 mol % PPh(3)AuNTf(2) at ambient temperature. The enolates undergo aldol reaction with an aldehyde present in the reaction mixture to give cyclic boronate esters, which can be subsequently transformed into phenols, biaryls, or dihydrobenzofurans via oxidation, Suzuki-Miyaura, or intramolecular Chan-Lam coupling, respectively. A combined gold/boronic acid catalyzed aldol condensation reaction of an alkynyl aldehyde was also successfully achieved.

  2. Kinetics of enzyme-catalyzed cross-linking of feruloylated arabinan from sugar beet

    DEFF Research Database (Denmark)

    Abang Zaidel, Dayang Norulfairuz; Arnous, Anis; Holck, Jesper

    2011-01-01

    the kinetics of HRP catalyzed cross-linking of FA esterified to α-(1,5)-linked arabinans are affected by the length of the arabinan chains carrying the feruloyl substitutions. The kinetics of the HRP-catalyzed cross-linking of four sets of arabinan samples from sugar beet pulp, having different molecular...... weights and hence different degrees of polymerization, were monitored by the disappearance of FA absorbance at 316 nm. MALDI-TOF/TOF-MS analysis confirmed that the sugar beet arabinans were feruloyl-substituted, and HPLC analysis verified that the amounts of diFAs increased when FA levels decreased...

  3. Modeling Lipase-Catalyzed Biodiesel Production in [BMIM][PF6

    Directory of Open Access Journals (Sweden)

    JianJun Yang

    2016-01-01

    Full Text Available Lipase-catalyzed biodiesel production models in room temperature ionic liquids (RTILs reaction medium available in the literature are valid especially for mixing intensity. In this paper, a preliminary model is established in order to try to describe the lipase-catalyzed biodiesel production process in RTILs in a stirring type bioreactor. Mixing intensity and time delay were inspected for the reaction model in [BMIM][PF6] medium. As a result, this model is a good explanation for these actual reaction conditions in RTILs. The model prediction curves well describe the experimental data indicating this bioenzymatic reaction model is effective and reliable in certain conditions.

  4. Synthesis of Fluoroalkoxy Substituted Arylboronic Esters by Iridium-Catalyzed Aromatic C–H Borylation

    KAUST Repository

    Batool, Farhat

    2015-08-17

    The preparation of fluoroalkoxy arylboronic esters by iridium-catalyzed aromatic C–H borylation is described. The fluoroalkoxy groups employed include trifluoromethoxy, difluoromethoxy, 1,1,2,2-tetrafluoroethoxy, and 2,2-difluoro-1,3-benzodioxole. The borylation reactions were carried out neat without the use of a glovebox or Schlenk line. The regioselectivities available through the iridium-catalyzed C–H borylation are complementary to those obtained by the electrophilic aromatic substitution reactions of fluoroalkoxy arenes. Fluoroalkoxy arylboronic esters can serve as versatile building blocks.

  5. Monitoring lipase-catalyzed butterfat interesterification with rapesee oil by Fourier transform near-infrared spectroscopy

    DEFF Research Database (Denmark)

    Zhang, Hong; Mu, Huiling; Xu, Xuebing

    2006-01-01

    This work demonstrates the application of FT-NIR spectroscopy to monitor the enzymatic interesterification process for butterfat modification. The reactions were catalyzed by Lipozyme TL IM at 70 C for the blend of butterfat/rapeseed oil (70/30, w/w) in a packed-bed reactor. The blend and intere......This work demonstrates the application of FT-NIR spectroscopy to monitor the enzymatic interesterification process for butterfat modification. The reactions were catalyzed by Lipozyme TL IM at 70 C for the blend of butterfat/rapeseed oil (70/30, w/w) in a packed-bed reactor. The blend...

  6. Reactivity and Chemoselectivity of Allenes in Rh(I)-Catalyzed Intermolecular (5 + 2) Cycloadditions with Vinylcyclopropanes: Allene-Mediated Rhodacycle Formation Can Poison Rh(I)-Catalyzed Cycloadditions

    Science.gov (United States)

    2015-01-01

    Allenes are important 2π building blocks in organic synthesis and engage as 2-carbon components in many metal-catalyzed reactions. Wender and co-workers discovered that methyl substituents on the terminal allene double bond counterintuitively change the reactivities of allenes in [Rh(CO)2Cl]2-catalyzed intermolecular (5 + 2) cycloadditions with vinylcyclopropanes (VCPs). More sterically encumbered allenes afford higher cycloadduct yields, and such effects are also observed in other Rh(I)-catalyzed intermolecular cycloadditions. Through density functional theory calculations (B3LYP and M06) and experiment, we explored this enigmatic reactivity and selectivity of allenes in [Rh(CO)2Cl]2-catalyzed intermolecular (5 + 2) cycloadditions with VCPs. The apparent low reactivity of terminally unsubstituted allenes is associated with a competing allene dimerization that irreversibly sequesters rhodium. With terminally substituted allenes, steric repulsion between the terminal substituents significantly increases the barrier of allene dimerization while the barrier of the (5 + 2) cycloaddition is not affected, and thus the cycloaddition prevails. Computation has also revealed the origin of chemoselectivity in (5 + 2) cycloadditions with allene-ynes. Although simple allene and acetylene have similar reaction barriers, intermolecular (5 + 2) cycloadditions of allene-ynes occur exclusively at the terminal allene double bond. The terminal double bond is more reactive due to the enhanced d−π* backdonation. At the same time, insertion of the internal double bond of an allene-yne has a higher barrier as it would break π conjugation. Substituted alkynes are more difficult to insert compared with acetylene, because of the steric repulsion from the additional substituents. This leads to the greater reactivity of the allene double bond relative to the alkynyl group in allene-ynes. PMID:25379606

  7. A 11-Steps Total Synthesis of Magellanine through a Gold(I)-Catalyzed Dehydro Diels-Alder Reaction.

    Science.gov (United States)

    McGee, Philippe; Bétournay, Geneviève; Barabé, Francis; Barriault, Louis

    2017-01-12

    We have developed an innovative strategy for the formation of angular carbocycles via a gold(I)-catalyzed dehydro Diels-Alder reaction. This transformation provides rapid access to a variety of complex angular cores in excellent diastereoselectivities and high yields. The usefulness of this Au(I) -catalyzed cycloaddition was further demonstrated by accomplishing a 11-steps total synthesis of (±)-magellanine.

  8. Development of melamine modified urea formaldehyde resins based o nstrong acidic pH catalyzed urea formaldehyde polymer

    Science.gov (United States)

    Chung-Yun Hse

    2009-01-01

    To upgrade the performance of urea-formaldehyde (UF) resin bonded particleboards, melamine modified urea-formaldehyde (MUF) resins based on strong acidic pH catalyzed UF polymers were investigated. The study was conducted in a series of two experiments: 1) formulation of MUF resins based on a UF polymer catalyzed with strong acidic pH and 2) determination of the...

  9. Large acceleration of α-chymotrypsin-catalyzed dipeptide formation by 18-crown-6 in organic solvents

    NARCIS (Netherlands)

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

    1998-01-01

    The effects of 18-crown-6 on the synthesis of peptides catalyzed by α-chymotrypsin are reported. Lyophilization of the enzyme in the presence of 50 equivalents of 18-crown-6 results in a 425-fold enhanced activity when the reaction between the 2-chloroethylester of N-acetyl-L-phenylalanine and L-phe

  10. Metal-ion catalyzed polymerization in the eutectic phase in water-ice

    DEFF Research Database (Denmark)

    Monnard, Pierre-Alain; Szostak, Jack W.

    2008-01-01

    The emergence of an RNA world requires among other processes the non-enzymatic, template-directed replication of genetic polymers such as RNA or related nucleic acids, possibly catalyzed by metal ions. The absence of uridilate derivative polymerization on adenine containing templates has been the...

  11. Asymmetric hydrogenation of quinolines catalyzed by iridium complexes of monodentate BINOL-derived phosphoramidites

    NARCIS (Netherlands)

    Mrsic, Natasa; Lefort, Laurent; Boogers, Jeroen A. F.; Minnaard, Adriaan J.; Feringa, Ben L.; de Vries, Johannes G.; Mršić, Nataša

    The monodentate BINOL-derived phosphoramidite PipPhos is used as ligand for the iridium-catalyzed asymmetric hydrogenation of 2- and 2,6-substituted quinolines. If tri-ortho-tolylphosphine and/or chloride salts are used as additives enantioselectivities are strongly enhanced up to 89%. NMR indicates

  12. Redox-Neutral Rh(III)-Catalyzed Olefination of Carboxamides with Trifluoromethyl Allylic Carbonate.

    Science.gov (United States)

    Park, Jihye; Han, Sangil; Jeon, Mijin; Mishra, Neeraj Kumar; Lee, Seok-Yong; Lee, Jong Suk; Kwak, Jong Hwan; Um, Sung Hee; Kim, In Su

    2016-11-18

    The rhodium(III)-catalyzed olefination of various carboxamides with α-CF3-substituted allylic carbonate is described. This reaction provides direct access to linear CF3-allyl frameworks with complete trans-selectivity. In particular, a rhodium catalyst provided Heck-type γ-CF3-allylation products via the β-O-elimination of rhodacycle intermediate and subsequent olefin migration process.

  13. Rh(III-catalyzed directed C–H bond amidation of ferrocenes with isocyanates

    Directory of Open Access Journals (Sweden)

    Satoshi Takebayashi

    2012-10-01

    Full Text Available [RhCp*(OAc2(H2O] [Cp* = pentamethylcyclopentadienyl] catalyzed the C–H bond amidation of ferrocenes possessing directing groups with isocyanates in the presence of 2 equiv/Rh of HBF4·OEt2. A variety of disubstituted ferrocenes were prepared in high yields, or excellent diastereoselectivities.

  14. Synthesis of 2-substituted tetraphenylenes via transition-metal-catalyzed derivatization of tetraphenylene

    Science.gov (United States)

    Pan, Shulei; Jiang, Hang; Zhang, Yu; Chen, Dushen

    2016-01-01

    Summary A new strategy for the synthesis of 2-substituted tetraphenylenes through a transition-metal-catalyzed derivatization has been developed. Three types of functionalities, including OAc, X (Cl, Br, I) and carbonyl, were introduced onto tetraphenylene, which allows the easy access to a variety of monosubstituted tetraphenylenes. These reactions could accelerate research on the properties and application of tetraphenylene derivatives. PMID:27559378

  15. Enantioselective addition of diphenyl phosphonate to ketimines derived from isatins catalyzed by binaphthyl-modified organocatalysts

    Science.gov (United States)

    Jang, Hee Seung; Kim, Yubin

    2016-01-01

    Summary Chiral binaphthyl-modified squaramide-catalyzed enantioselective addition of diphenyl phosphonate to ketimines derived from isatins has been achieved. This method affords practical and efficient access to chiral 3-amino-3-phosphonyl-substituted oxindole derivatives in high yields with excellent enantioselectivities (up to 99% ee). PMID:27559405

  16. Synthesis of a novel chemotype via sequential metal-catalyzed cycloisomerizations

    Directory of Open Access Journals (Sweden)

    Bo Leng

    2012-08-01

    Full Text Available Sequential cycloisomerizations of diynyl o-benzaldehyde substrates to access novel polycyclic cyclopropanes are reported. The reaction sequence involves initial Cu(I-mediated cycloisomerization/nucleophilic addition to an isochromene followed by diastereoselective Pt(II-catalyzed enyne cycloisomerization.

  17. Practical and General Palladium-Catalyzed Synthesis of Ketones from Internal Olefins

    KAUST Repository

    Morandi, Bill

    2013-01-16

    Make it simple! A convenient and general palladium-catalyzed oxidation of internal olefins to ketones is reported. The transformation occurs at room temperature and shows wide substrate scope. Applications to the oxidation of seed-oil derivatives and a bioactive natural product (see scheme) are described, as well as intriguing mechanistic features.

  18. Memory effects in palladium-catalyzed allylic Alkylations of 2-cyclohexen-1-yl acetate

    DEFF Research Database (Denmark)

    Svensen, Nina; Fristrup, Peter; Tanner, David Ackland

    2007-01-01

    The objective of this work was to characterize the enantiospecificity of the allylic alkylation of enantioenriched 2-cyclohexen-1-yl acetate with the enolate ion of dimethyl malonate catalyzed by unsymmetrical palladium catalysts. The precatalysts employed were (eta(3)-allyl)PdLCl, where L...

  19. Enantioselective Evans-Tishchenko Reduction of b-Hydroxyketone Catalyzed by Lithium Binaphtholate

    Directory of Open Access Journals (Sweden)

    Makoto Nakajima

    2011-06-01

    Full Text Available Lithium diphenylbinaphtholate catalyzed the enantioselective Evans-Tishchenko reduction of achiral b-hydroxyketones to afford monoacyl-protected 1,3-diols with high stereoselectivities. In the reaction of racemic b-hydroxyketones, kinetic optical resolution occurred in a highly stereoselective manner.

  20. Palladium-Catalyzed Cross-Coupling Reactions of Perfluoro Organic Compounds

    Directory of Open Access Journals (Sweden)

    Masato Ohashi

    2014-09-01

    Full Text Available In this review, we summarize our recent development of palladium(0-catalyzed cross-coupling reactions of perfluoro organic compounds with organometallic reagents. The oxidative addition of a C–F bond of tetrafluoroethylene (TFE to palladium(0 was promoted by the addition of lithium iodide, affording a trifluorovinyl palladium(II iodide. Based on this finding, the first palladium-catalyzed cross-coupling reaction of TFE with diarylzinc was developed in the presence of lithium iodide, affording α,β,β-trifluorostyrene derivatives in excellent yield. This coupling reaction was expanded to the novel Pd(0/PR3-catalyzed cross-coupling reaction of TFE with arylboronates. In this reaction, the trifluorovinyl palladium(II fluoride was a key reaction intermediate that required neither an extraneous base to enhance the reactivity of organoboronates nor a Lewis acid additive to promote the oxidative addition of a C–F bond. In addition, our strategy utilizing the synergetic effect of Pd(0 and lithium iodide could be applied to the C–F bond cleavage of unreactive hexafluorobenzene (C6F6, leading to the first Pd(0-catalyzed cross-coupling reaction of C6F6 with diarylzinc compounds.

  1. Highly selective formation of imines catalyzed by silver nanoparticles supported on alumina

    DEFF Research Database (Denmark)

    Mielby, Jerrik Jørgen; Poreddy, Raju; Engelbrekt, Christian

    2014-01-01

    The oxidative dehydrogenation of alcohols to aldehydes catalyzed by Ag nanoparticles supported on Al2O3 was studied. The catalyst promoted the direct formation of imines by tandem oxidative dehydrogenation and condensation of alcohols and amines. The reactions were performed under mild conditions...

  2. Aminofluorination of 2-alkynylanilines: a Au-catalyzed entry to fluorinated indoles

    Directory of Open Access Journals (Sweden)

    Antonio Arcadi

    2014-02-01

    Full Text Available The scope and limitations of gold-catalyzed tandem cycloisomerization/fluorination reactions of unprotected 2-alkynylanilines to have access to 3,3-difluoro-2-aryl-3H-indoles and 3-fluoro-2-arylindoles are described. An unprecedented aminoauration/oxidation/fluorination cascade reaction of 2-alkynylanilines bearing a linear alkyl group on the terminal triple bond is reported.

  3. Surprisingly Mild Enolate-Counterion-Free Pd(0)-Catalyzed Intramolecular Allylic Alkylations

    DEFF Research Database (Denmark)

    Madec, David; Prestat, Guillaume; Martini, Elisabetta;

    2005-01-01

    Palladium-catalyzed intramolecular allylic alkylations of unsaturated EWG-activated amides can take place under phase-transfer conditions or in the presence of a crown ether. These new reaction conditions are milder and higher yielding than those previously reported. A rationalization for such an...

  4. The Extension Storyteller: Using Stories to Enhance Meaning and Catalyze Change

    Science.gov (United States)

    Franz, Nancy

    2016-01-01

    Many cultures share and pass on norms through storytelling. Extension as a culture also creates and shares stories to pass on history, provide information about Extension work and experiences, and develop the organization. However, Extension as a culture less frequently uses storytelling to enhance meaning and catalyze related change. This article…

  5. Optimizing the Acid Catalyzed Synthesis of Hyperbranched Poly(Glycerol-diacids) Oligomers

    Science.gov (United States)

    Oligomeric pre-polymers were synthesized by the acid-catalyzed condensation of glycerol with succinic acid, glutaric acid and azelaic acid in dimethylsulfoxide (DMSO) or dimethylformamide (DMF). The prepolymers were obtained, on average in 84% yield, and were characterized by proton NMR, MALDI-TOF ...

  6. Direct 2-acetoxylation of quinoline N-oxides via copper catalyzed C-H bond activation.

    Science.gov (United States)

    Chen, Xuan; Zhu, Chongwei; Cui, Xiuling; Wu, Yangjie

    2013-08-07

    An efficient and direct 2-acetoxylation of quinoline N-oxides via copper(I) catalyzed C-H bond activation has been developed. This transformation was achieved using TBHP as an oxidant in the cross-dehydrogenative coupling (CDC) reaction of quinoline N-oxides with aldehydes, and provided a practical pathway to 2-acyloxyl quinolines.

  7. Copper(II)-catalyzed electrophilic amination of quinoline N-oxides with O-benzoyl hydroxylamines.

    Science.gov (United States)

    Li, Gang; Jia, Chunqi; Sun, Kai; Lv, Yunhe; Zhao, Feng; Zhou, Kexiao; Wu, Hankui

    2015-03-21

    Copper acetate-catalyzed C-H bond functionalization amination of quinoline N-oxides was achieved using O-benzoyl hydroxylamine as an electrophilic amination reagent, thereby affording the desired products in moderate to excellent yields. Electrophilic amination can also be performed in good yield on a gram scale.

  8. Palladium-catalyzed conversion of aryl and vinyl triflates to bromides and chlorides.

    Science.gov (United States)

    Shen, Xiaoqiang; Hyde, Alan M; Buchwald, Stephen L

    2010-10-13

    The palladium-catalyzed conversion of aryl and vinyl triflates to aryl and vinyl halides (bromides and chlorides) has been developed using dialkylbiaryl phosphine ligands. A variety of aryl, heteroaryl, and vinyl halides can be prepared via this method in good to excellent yields.

  9. Palladium-catalyzed carbonylation reaction of aryl bromides with 2-hydroxyacetophenones to form flavones.

    Science.gov (United States)

    Wu, Xiao-Feng; Neumann, Helfried; Beller, Matthias

    2012-10-01

    Flavone of the month: a general and efficient method for the palladium-catalyzed carbonylative synthesis of flavones has been developed. Starting from aryl bromides and 2-hydroxyacetophenones, the corresponding flavones have been isolated in good yields. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Palladium-catalyzed amination of unprotected five-membered heterocyclic bromides.

    Science.gov (United States)

    Su, Mingjuan; Hoshiya, Naoyuki; Buchwald, Stephen L

    2014-02-07

    An efficient method for the palladium-catalyzed amination of unprotected bromoimidazoles and bromopyrazoles is presented. The transformation is facilitated by the use of our newly developed Pd precatalyst based on the bulky biarylphosphine ligand tBuBrettPhos (L4). The mild reaction conditions employed allow for the preparation of a broad scope of aminoimidazoles and aminopyrazoles in moderate to excellent yields.

  11. An improved palladium-catalyzed conversion of aryl and vinyl triflates to bromides and chlorides.

    Science.gov (United States)

    Pan, Jun; Wang, Xinyan; Zhang, Yong; Buchwald, Stephen L

    2011-09-16

    A facile Pd-catalyzed conversion of aryl and vinyl triflates to aryl and vinyl halides (bromides and chlorides) is described. This method allows convenient access to a variety of aryl, heteroaryl, and vinyl halides in good to excellent yields and with greatly simplified conditions relative to our previous report. © 2011 American Chemical Society

  12. Efficient palladium-catalyzed coupling reactions of aryl bromides and chlorides with phenols.

    Science.gov (United States)

    Hu, Tongjie; Schulz, Thomas; Torborg, Christian; Chen, Xiaorong; Wang, Jun; Beller, Matthias; Huang, Jun

    2009-12-21

    A convenient and general palladium-catalyzed coupling reaction of aryl bromides and chlorides with phenols was developed. Various functional groups such as nitriles, aldehydes, ketones and esters are well tolerated and the corresponding products are obtained in good to excellent yield.

  13. Highly efficient synthesis of phenols by copper-catalyzed hydroxylation of aryl iodides, bromides, and chlorides.

    Science.gov (United States)

    Yang, Kai; Li, Zheng; Wang, Zhaoyang; Yao, Zhiyi; Jiang, Sheng

    2011-08-19

    8-Hydroxyquinolin-N-oxide was found to be a very efficient ligand for the copper-catalyzed hydroxylation of aryl iodides, aryl bromides, or aryl chlorides under mild reaction conditions. This methodology provides a direct transformation of aryl halides to phenols and to alkyl aryl ethers. The inexpensive catalytic system showed great functional group tolerance and excellent selectivity. © 2011 American Chemical Society

  14. Palladium-catalyzed carbonylative sonogashira coupling of aryl bromides using near stoichiometric carbon monoxide

    DEFF Research Database (Denmark)

    Neumann, Karoline T.; Laursen, Simon R.; Lindhardt, Anders T.

    2014-01-01

    A general procedure for the palladium-catalyzed carbonylative Sonogashira coupling of aryl bromides is reported, using near stoichiometric amounts of carbon monoxide. The method allows a broad substrate scope in moderate to excellent yields. The formed alkynone motive serves as a platform...

  15. NHC-Catalyzed/Titanium(IV);#8722;Mediated Highly Diastereo- and Enantioselective Dimerization of Enals

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Daniel T.; Cardinal-David, Benoit; Roberts, John M.; Sarjeant, Amy A.; Scheidt, Karl A. (NWU)

    2012-05-09

    An NHC-catalyzed, diastereo- and enantioselective dimerization of enals has been developed. The use of Ti(Oi-Pr){sub 4} is a key element for the reactivity and selectivity of this process. The cyclopentenes are obtained with high levels of diastereo- and enantioselectivity and their synthetic utility is demonstrated by functionalization of the product alkene.

  16. A Palladium-Catalyzed Vinylcyclopropane (3 + 2) Cycloaddition Approach to the Melodinus Alkaloids

    KAUST Repository

    Goldberg, Alexander F. G.

    2011-08-19

    A palladium-catalyzed (3+2) cycloaddition of a vinylcyclopropane and a β-nitrostyrene is employed to rapidly assemble the cyclopentane core of the Melodinus alkaloids. The ABCD ring system of the natural product family is prepared in six steps from commercially available materials.

  17. Asymmetric Cyclization of N-Sulfonyl Alkenyl Amides Catalyzed by Iridium/Chiral Diene Complexes.

    Science.gov (United States)

    Nagamoto, Midori; Yanagi, Tomoyuki; Nishimura, Takahiro; Yorimitsu, Hideki

    2016-09-16

    Iridium/chiral diene complexes efficiently catalyzed the asymmetric cyclization of N-sulfonyl alkenyl amides to give the corresponding 2-pyrrolidone derivatives with high enantioselectivity. A mechanistic study revealed that the reaction proceeds via nucleophilic attack of the amide on the alkene moiety.

  18. Cobalt-catalyzed hydrogenation of esters to alcohols: unexpected reactivity trend indicates ester enolate intermediacy.

    Science.gov (United States)

    Srimani, Dipankar; Mukherjee, Arup; Goldberg, Alexander F G; Leitus, Gregory; Diskin-Posner, Yael; Shimon, Linda J W; Ben David, Yehoshoa; Milstein, David

    2015-10-12

    The atom-efficient and environmentally benign catalytic hydrogenation of carboxylic acid esters to alcohols has been accomplished in recent years mainly with precious-metal-based catalysts, with few exceptions. Presented here is the first cobalt-catalyzed hydrogenation of esters to the corresponding alcohols. Unexpectedly, the evidence indicates the unprecedented involvement of ester enolate intermediates.

  19. Heteroaromatic sulfonates and phosphates as electrophiles in iron-catalyzed cross-couplings.

    Science.gov (United States)

    Gøgsig, Thomas M; Lindhardt, Anders T; Skrydstrup, Troels

    2009-11-01

    Employment of heteroaromatic tosylates and phosphates as suitable electrophiles in iron-catalyzed cross-coupling reactions with alkyl Grignard reagents is reported. These reactions are performed at low temperature allowing good functional group tolerance and full conversion is achieved within minutes. In addition, an aryl-aryl cross-coupling utilizing a heteroaryl sulfamate electrophile is reported.

  20. Palladium-Catalyzed Polyfluorophenylation of Porphyrins with Bis(polyfluorophenylzinc Reagents

    Directory of Open Access Journals (Sweden)

    Toshikatsu Takanami

    2013-10-01

    Full Text Available A facile and efficient method for the synthesis of pentafluorophenyl- and related polyfluorophenyl-substituted porphyrins has been achieved via palladium-catalyzed cross-coupling reactions of brominated porphyrins with bis(polyfluorophenylzinc reagents. The reaction is applicable to a variety of free-base bromoporphyrins, their metal complexes, and a number of bis(polyfluorophenylzinc reagents.