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Biphasic System (biphasic + system)
Selected AbstractsChemInform Abstract: Selective Dimerization of 1,6-Diynes Catalyzed by Ionic Liquid-Supported Nickel Complexes in an Ionic Liquid/Toluene Biphasic System.CHEMINFORM, Issue 25 2009Avijit Goswami Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Selective Hydrogenation of Unsaturated Aldehydes in a Poly(ethylene glycol)/Compressed Carbon Dioxide Biphasic System.CHEMINFORM, Issue 6 2009Ruixia Liu Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: A General Method for Nearly Reduction-Free Dehalogenations in a Fluorinated Biphasic System.CHEMINFORM, Issue 35 2008I. Wlassics Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A Novel Ytterbium/Perfluoroalkylated-Pyridine Catalyst for Baylis,Hillman Reaction in a Fluorous Biphasic System.CHEMINFORM, Issue 47 2007Wen-Bin Yi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Synthesis of Medium- and Large-Sized Lactones in an Aqueous,Organic Biphasic System.CHEMINFORM, Issue 35 2005Hidenori Kinoshita Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: An Asymmetric Catalytic Carbon,Carbon Bond Formation in a Fluorous Biphasic System Based on Perfluoroalkyl-BINOL.CHEMINFORM, Issue 9 2001Yuan Tian Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Polymeric Aqueous Biphasic Systems for Non-Contact Cell Printing on Cells: Engineering Heterocellular Embryonic Stem Cell NichesADVANCED MATERIALS, Issue 24 2010Hossein Tavana An optimized polymeric aqueous two-phase system allows direct and non-contact printing of cells onto a monolayer of living cells in arbitrary shapes as well as in a high-density microarray format to create heterocellular microenvironments and study the effect of direct cell,cell interactions on cell fate. The entire process is performed in aqueous media to support full cell viability and functionality. [source] Catalytic Hydroxylation in Biphasic Systems using CYP102A1 MutantsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2005Steffen Abstract Cytochrome P450 monooxygenases are biocatalysts that hydroxylate or epoxidise a wide range of hydrophobic organic substrates. Their technical application is, however, limited to a small number of whole-cell processes. The use of the isolated P450 enzymes is believed to be impractical due to their low stability, stoichiometric need of the expensive cofactor NAD(P)H and low solubility of most substrates in aqueous media. We investigated the behaviour of an isolated bacterial monooxygenase (mutants of CYP102A1) in a biphasic reaction system supported by cofactor recycling with the NADP+ -dependent formate dehydrogenase from Pseudomonas sp 101. Using this experimental set-up cyclohexane, octane and myristic acid were hydroxylated. To reduce the process costs a novel NADH-dependent mutant of CYP102A1 was designed. For recycling of NADH an NAD+ -dependent FDH was used. The stability of the monooxygenase mutants under the reaction conditions in the biphasic system was quite high as revealed by total turnover numbers of up to 12,850 in the NADPH-dependent cyclohexane hydroxylation and up to 30,000 in the NADH-dependent myristic acid oxidation. [source] Synthesis, characterization and catalytic activity of novel Co(II) and Pd(II)-perfluoroalkylphthalocyanine in fluorous biphasic system; benzyl alcohol oxidationAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 2 2009Metin Özer Abstract Tetrakis[heptadecafluorononyl] substituted phthalocyanine complexes were prepared by template synthesis from 4-(heptadecafluorononyloxy)phthalonitrile with Co(CH3COO)·2H2O or PdCl2 in 2- N, N -dimethylaminoethanol. The corresponding phthalonitrile was obtained from heptadecafluorononan-1-ol and 4-nitrophthalonitrile with K2CO3 in DMF at 50 °C. The structures of the compounds were characterized by elemental analysis, FTIR, UV,vis and MALDI-TOF MS spectroscopic methods. Metallophthalocyanines are soluble in fluoroalkanes such as perfluoromethylcyclohexane (PFMCH). The complexes were tested as catalysts for benzyl alcohol oxidation with tert -butylhydroperoxide (TBHP) in an organic,fluorous biphasic system (n -hexane,PFMCH). The oxidation of benzyl alcohol was also tested with different oxidants, such as hydrogen peroxide, m -chloroperoxybenzoic acid, molecular oxygen and oxone in n -hexane,PFMCH. TBHP was found to be the best oxidant for benzyl alcohol oxidation since higher conversion and selectivity were observed when this oxidant was used. Copyright © 2008 John Wiley & Sons, Ltd. [source] Solvent selection for enhanced bioproduction of 3-methylcatechol in a two-phase partitioning bioreactorBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2007George P. Prpich Abstract The biotransformation of toluene to 3-methycatechol (3MC) via Pseudomonas putida MC2 was used as a model system for the development of a biphasic process offering enhanced overall volumetric productivity. Three factors were investigated for the identification of an appropriate organic solvent and they included solvent toxicity, bioavailability of the solvent as well as solvent affinity for 3MC. The critical log P (log Pcrit) of the biocatalyst was found to be 3.1 and log P values were used to predict a solvent's toxicity. The presence of various functional groups of candidate solvents were used to predict the absorption of 3MC and it was found that solvents possessing polarity showed an affinity towards 3MC. Bis (2-ethylhexyl) sebecate was selected for use in the biphasic system as it fulfilled all selection criteria. A two-phase biotransformation with BES and a 50% phase volume ratio, achieved an overall volumetric productivity of 440 mg 3MC/L-h, which was an improvement by a factor of approximately 4 over previously operated systems. Additional work focused on reducing the toluene feed in order to minimize possible toxicity and decrease loss of substrate (toluene), a result of volatilization. Toluene losses were reduced by a factor of 4, compared to previously operated systems, without suffering an appreciable loss in overall volumetric productivity. Biotechnol. Bioeng. 2007;97: 536,543. © 2006 Wiley Periodicals, Inc. [source] Microbial synthesis of ethyl (R)-4,4,4-trifluoro-3-hydroxybutanoate by asymmetric reduction of ethyl 4,4,4-trifluoroacetoacetate in an aqueous-organic solvent biphasic systemBIOTECHNOLOGY JOURNAL, Issue 2 2007Junyao He Abstract In this study, whole cells of Saccharomyces uvarum SW-58 were applied in an aqueous-organic solvent biphasic system for the asymmetric reduction of ethyl 4,4,4-trifluoroacetoacetate to ethyl (R)-4,4,4-trifluoro-3-hydroxybutanoate [(R)-2]. The results of reduction in different aqueous-organic solvent biphasic systems showed that dibutylphthalate provided the best compromise between the biocompatibility and the partition of substrate and product among the solvents tested. To optimize the reaction, several factors such as reaction pH, temperature, shaking speed, volume ratio of the aqueous phase to the organic phase and ratio of biomass/substrate were investigated. It was found that the change of these factors obviously influenced the conversion and initial reaction rate, and had a minor effect on the enatiomeric excess of the product. Under the optimal conditions, 85.0% of conversion and 85.2% of enatiomeric excess were achieved. The bioconversion in the biphasic system was more efficient compared with that in the monophasic aqueous system, and product concentration as high as 54.6 g/L was reached in the organic phase without addition of co-enzyme. [source] Homogeneous esterification by lipase from Burkholderia cepacia in the fluorinated solventBIOTECHNOLOGY PROGRESS, Issue 6 2008S. Shipovskov Abstract The formation of noncovalent complexes between lipase from Burkholderia cepacia and the fluorinated ionic surfactant Kryto Development Product 4606 KDP was shown to promote the solubilization of the enzyme in the fluorinated solvent perfluoro(methylcyclohexane) (PFMC) and its operation as a catalyst in the fluorous PFMC/hexane biphasic system (FBS). In the reaction of esterification of 1-phenylethanol and vinyl acetate, the solubilized lipase showed high stereospecificity (ca. 99%) with a catalytic efficiency up to 56 nmol/(U h) with a high operational and storage stability. Temperature modulation of the FBS miscibility allowed the separation and recovery of the solubilized lipase for at least three times. The results are of practical importance for the development of recoverable biocatalysts soluble and active in the FBS. [source] Multiphase Systems for the Recycling of Alkoxycarbonylation CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 12-13 2006Jeroen J., M. de Pater Abstract This review evaluates the various multiphasic systems that have been developed for catalyst recycling in the context of alkoxycarbonylation of alkenes and alkynes. Immobilization of the catalyst on an insoluble support, such as silica, alumina, clay or a polymer, as well as immobilization in the inorganic phase of several liquid/liquid biphasic systems (aqueous/organic, ionic liquid/organic, fluorous/organic or supercritical CO2/organic) has been described. In several cases detailed information on the efficiency of catalyst separation and recycling is available. Most of the work was focused on the alkoxycarbonylation reactions of alkenes, for which several efficient methods for catalyst recycling were demonstrated. The recycling of catalyst through specific precipitation from supercritical CO2 or selective dissolution in a fluorous phase, has received only scant attention but offers many opportunities for further improvement. [source] Highly Selective Biphasic Telomerization of Butadiene with Glycols: Scope and LimitationsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11 2003Arno Behr Abstract Highly selective telomerization reactions of a number of short-chain glycol nucleophiles with 1,3-butadiene have been achieved in aqueous biphasic systems employing the water-soluble catalyst system Pd(acac)2/TPPTS. For all substrates the selectivity for the obtained monotelomers 5,7 reached ,95% whereas butadiene dimers 3, octadienols 4 and ditelomers like 2 were produced only in trace amounts. The order of reactivity is ethylene glycol>>1,3-propylene glycol , glycerol>1,4-butylene glycol, which is in agreement with generally observed trends. The scope and limitations of these reactions are discussed in terms of obtained yields and achievable catalyst productivities (total turnover numbers). [source] Microbial synthesis of ethyl (R)-4,4,4-trifluoro-3-hydroxybutanoate by asymmetric reduction of ethyl 4,4,4-trifluoroacetoacetate in an aqueous-organic solvent biphasic systemBIOTECHNOLOGY JOURNAL, Issue 2 2007Junyao He Abstract In this study, whole cells of Saccharomyces uvarum SW-58 were applied in an aqueous-organic solvent biphasic system for the asymmetric reduction of ethyl 4,4,4-trifluoroacetoacetate to ethyl (R)-4,4,4-trifluoro-3-hydroxybutanoate [(R)-2]. The results of reduction in different aqueous-organic solvent biphasic systems showed that dibutylphthalate provided the best compromise between the biocompatibility and the partition of substrate and product among the solvents tested. To optimize the reaction, several factors such as reaction pH, temperature, shaking speed, volume ratio of the aqueous phase to the organic phase and ratio of biomass/substrate were investigated. It was found that the change of these factors obviously influenced the conversion and initial reaction rate, and had a minor effect on the enatiomeric excess of the product. Under the optimal conditions, 85.0% of conversion and 85.2% of enatiomeric excess were achieved. The bioconversion in the biphasic system was more efficient compared with that in the monophasic aqueous system, and product concentration as high as 54.6 g/L was reached in the organic phase without addition of co-enzyme. [source] Operational concept for the improved synthesis of (R)-3,3'-furoin and related hydrophobic compounds with benzaldehyde lyaseBIOTECHNOLOGY JOURNAL, Issue 5 2006Marion B. Ansorge-Schumacher Dr. Abstract Biphasic reaction systems for enzyme catalysis are an elegant way to overcome limited solubility and stability of reactants and facilitate continuous processes. However, many synthetically useful enzymes are not stable in biphasic systems of water and organic solvent. The entrapment in polymer beads of polyvinyl alcohol has been shown to enable the stable operation of enzymes unstable in conventional biphasic reaction systems. We report the extension of this concept to continuous operation in a fluidised bed reactor. The enzyme benzaldehyde lyase was used for the continuous synthesis of enantiopure (R)-3,3'-furoin. The results show enhanced stability with half-life times under operation conditions of more than 100 h, as well as superior enzyme utilisation in terms of productivity. Furthermore, racemisation and oxidation of the product could be successfully prevented under the non-aqueous and inert reaction conditions. [source] Importance of Interfacial Adsorption in the Biphasic Hydroformylation of Higher Olefins Promoted by Cyclodextrins: A Molecular Dynamics Study at the Decene/Water InterfaceCHEMISTRY - A EUROPEAN JOURNAL, Issue 7 2007Nicolas Sieffert Abstract We report herein a molecular dynamics study of the main species involved in the hydroformylation of higher olefins promoted by cyclodextrins in 1-decene/water biphasic systems at a temperature of 350,K. The two liquids form a well-defined sharp interface of approximately 7,Å width in the absence of solute; the decene molecules are generally oriented "parallel" to the interface where they display transient contacts with water. We first focused on rhodium complexes bearing water-soluble TPPTS3, ligands (where TPPTS3, represents tris(m -sulfonatophenyl)phosphine) involved in the early steps of the reaction. The most important finding concerned the surface activity of the "active" form of the catalyst [RhH(CO)(TPPTS)2]6,, the [RhH(CO)2(TPPTS)2]6, complex, and the key reaction intermediate [RhH(CO)(TPPTS)2(decene)]6, (with the olefin ,-coordinated to the metal center) which are adsorbed at the water side of the interface in spite of their ,6 charge. The free TPPTS3, ligands themselves are also surface-active, whereas the ,9 charged catalyst precursor [RhH(CO)(TPPTS)3]9, prefers to be solubilized in water. The role of cyclodextrins was then investigated by performing simulations on 2,6-dimethyl-,-cyclodextrin ("CD") and its inclusion complexes with the reactant (1-decene), a reaction product (undecanal), and the corresponding key reaction intermediate [RhH(CO)(TPPTS)2(decene)]6, as guests; they were all shown to be surface-active and prefer the interface over the bulk aqueous phase. These results suggest that the biphasic hydroformylation of higher olefins takes place "right" at the interface and that the CDs promote the "meeting" of the olefin and the catalyst in this peculiar region of the solution by forming inclusion complexes "preorganized" for the reaction. Our results thus point to the importance of adsorption at the liquid/liquid interface in this important phase-transfer-catalyzed reaction. [source] | |||||||||||||