Reactions In Organic Media Research Articles

Synthesis of Amphiphilic Polymer Particles for Lipase Immobilization

To develop a novel support of enzymes for use in the enzymatic reactions in organic media, amphiphilic polymer particles which have both a hydrophilic amino group and hydrophobic acyl group were synthesized. Using Rhizopus delemar lipase as a model enzyme, the effects of the kinds of the amino group and the number of carbon atoms in the chain of the acyl group of the amphiphilic polymer particles on the amount of lipase immobilized, and the organic solvent stability and the transesterification activity of the immobilized lipase in hexane were studied. Amphiphilic polymer particles in which a guanidino group and stearoyl group were introduced as the amino group and the acyl group, respectively, were the best particles that we tested in the present work.

Novel microbial lipases: catalytic activity in reactions in organic media.

2,000 microbial strains were isolated from soil samples and tested to determine their lipolytic activity by employing screening techniques on solid and in liquid media. Culture broths were initially tested with 1,2-O-dilauryl-rac-glycero-3-glutaric acid-resorufinyl ester, a chromogenic substrate specific for lipases. Fourteen lipase-producing microorganisms were selected and their taxonomic identification was carried out. Hydrolysis of tributyrin or olive oil and the esterification of oleic acid with heptanol were selected to preliminary evaluate the catalytic activity of these lipases. All the selected lipases catalysed this esterification reaction with good yields. Resolution of (R,S)-2-(4-isobutylphenyl) propionic acid, (R,S)-1-phenylethanol, (R,S) 1-phenylethylamine and of (R) or (S) glycidol were performed to evaluate the stereoselectivity of these novel enzymes as biocatalysts in reactions in organic media. Lipases from the fungi Fusarium oxysporum and Ovadendron sulphureo-ochraceum gave the best yields and enantioselectivities in the resolution of racemic ibuprofen and 1-phenylethanol. Several lipases displayed a high stereoselectivity in the resolution of chiral amines by an alcoxycarbonylation reaction.

Preparative regio- and chemoselective functionalization of hydrocarbons catalyzed by cell free preparations of 2-hydroxybiphenyl 3-monooxygenase

Oxygenases are useful catalysts for the selective incorporation of molecular oxygen into hydrocarbons. Here, we report on the application of isolated, cell free 2-hydroxybiphenyl 3-monooxygenase (HbpA) as catalyst for the regio- and chemospecific hydroxylation of 2-hydroxybiphenyl to 2,3-dihydroxybiphenyl. The catalyst was prepared from recombinant Escherichia coli using expanded bed adsorption chromatography and could be stored without significant loss of activity in lyophilized form. The reaction was performed in an aerated and thermostated simple stirred glass vessel in an aqueous (20% v/v)/organic (80% v/v) reaction medium. This allowed in situ product recovery preventing substrate and product inhibition of the catalyst as well as decay of the labile product 2,3-dihydroxybiphenyl. Enzymatic regeneration of reduced nicotinamide cofactors was achieved using the formate/formate dehydrogenase system. We obtained volumetric productivities of up to 0.45 g l−1 h−1. No significant decrease of productivity was observed within 7 h and more. Product purification (purity 92%) was achieved using solid phase extraction with aluminum oxide followed by crystallization as a polishing step (purity>99%).To our knowledge, these results show for the first time the perspectives of integrated enzyme and cofactor regeneration-based biocatalytic processes in organic/aqueous emulsions, coupled with in situ product recovery.

Design of a continuous process for the production of highly substituted granular carboxymethyl starch

A process design for the continuous production of highly substituted granular carboxymethyl starch (CMS) from potato starch is presented. Experiments in a batch reactor showed that aqueous isopropyl alcohol (IPA) is the optimal reaction medium to prevent the substituted starch from swelling and to keep it in a granular form. The degree of substitution (DS) that can be obtained in a single reaction step is limited to about 1.3. It is possible to increase the DS in a consecutive batch reaction where a lower water concentration is used. The continuous process consists of two continuous stirred tank reactors in series, each with a specific H 2O/IPA ratio. For a complete recycling of the organic reaction medium a hybrid dehydration section is evaluated. Based on this design, granular carboxymethyl potato starch with a DS of 1.5 or higher can be produced continuously. For an annual production of 3600 tons of CMS, the first CSTR should have: a starch content of 20% (w/w); a H 2O/IPA ratio of 10/90 w/ w ; a temperature of 40°C; a volume of 11 m 3 ; and a residence time of 4.5 h . To increase the DS to 1.5, the intermediate CMS, with a DS of 0.8, is fed to the second CSTR, having a starch content of 20% (w/w); a H 2O/IPA ratio of 5/95 w/ w ; a temperature of 40°C; a volume of 7.4 m 3 ; and a residence time of 3.6 h .

Selectivity of Rhizomucor miehei lipase as affected by choice of cosubstrate system in ester modification reactions in organic media

Selectivity of Rhizomucor miehei lipase as affected by choice of cosubstrate system in ester modification reactions in organic media

Selectivity of Candida antarctica B lipase toward fatty acid and (Iso)propanol substrates in esterification reactions in organic media.

Fatty acid (FA) selectivity of immobilized Candida antarctica B lipase was assessed as influenced by various cosubstrate systems for ester synthesis. Reaction mixtures contained a homologous series of even-chain n-acyl donor (C(4)(-)(16)) substrates (FA or their methyl esters, FAME) and a single alcohol cosubstrate (propanol, 2-propanol, or their acetate derivatives) in hexane. Multiple FA optima were often observed, with preferences for C(6) (or C(4)) followed by C(14) and sometimes C(10). The degree of selectivity among acyl donors was modest (up to 1.28-2.60, based on ratios of selectivity constants) and was dependent on the choice of cosubstrate system. Acyl group selectivity ranged up to 1.31-1.36 for [FA + alcohol], 1. 48-2.60 for [FAME + alcohol], 1.30-1.72 for [FA + alcohol acetate], and 1.28-1.88 [FAME + alcohol acetate] reaction systems. General shifts in selectivity were observed between short-chain (C(4)(-)(8)) and long-chain (C(10)(-)(16)) FA as groups with propanol cosubstrate, whereas shifts in reaction selectivity were observed toward specific FA(s) for 2-propanol cosubstrate. Selectivity among a series of alcohol cosubstrates ranged up to 13-fold in esterification reactions with C(6) FA.

00/00763 Utilization of hard-coal mining washing wastes and red mud for the production of expanded-clay granulate

Oxygenases are useful catalysts for the selective incorporation of molecular oxygen into hydrocarbons. Here, we report on the application of isolated, cell free 2-hydroxybiphenyl 3-monooxygenase (HbpA) as catalyst for the regio- and chemospecific hydroxylation of 2-hydroxybiphenyl to 2,3-dihydroxybiphenyl. The catalyst was prepared from recombinant Escherichia coli using expanded bed adsorption chromatography and could be stored without significant loss of activity in lyophilized form. The reaction was performed in an aerated and thermostated simple stirred glass vessel in an aqueous (20% v/v)/organic (80% v/v) reaction medium. This allowed in situ product recovery preventing substrate and product inhibition of the catalyst as well as decay of the labile product 2,3-dihydroxybiphenyl. Enzymatic regeneration of reduced nicotinamide cofactors was achieved using the formate/formate dehydrogenase system. We obtained volumetric productivities of up to 0.45 g l−1 h−1. No significant decrease of productivity was observed within 7 h and more. Product purification (purity 92%) was achieved using solid phase extraction with aluminum oxide followed by crystallization as a polishing step (purity>99%).To our knowledge, these results show for the first time the perspectives of integrated enzyme and cofactor regeneration-based biocatalytic processes in organic/aqueous emulsions, coupled with in situ product recovery.

Selectivity of Rhizomucor miehei lipase as affected by choice of cosubstrate system in ester modification reactions in organic media.

Fatty acid (FA) selectivity of immobilized Rhizomucor miehei lipase was determined for various cosubstrate systems for ester modification involving competing n-acyl-donor substrates of even-chain length (C4-C16; FA or their methyl esters, FAME) and either n-propanol or propyl acetate in hexane. Acyl-chain-length optima were observed for C8 and C14/16 in all cases. Upon changing between cosubstrate systems of [FA + propanol] to [FAME + propanol] to [FAME + propyl acetate], there was a general shift in selectivity toward shorter-chain-length FA (C4-C8). The greatest degree of reaction selectivity (based on ratios of selectivity constants) among the FA substrates was 3.1 for the [FA + propanol], 2.5 for the [FAME + propanol], and 1.4 for the [FAME + propyl acetate] cosubstrate systems. For esterification reactions between C6 FA and reactive members of a series of aliphatic and aromatic alcohols, the greatest degree of selectivity observed was 3.6.

Biosensors Based on a Light-Addressable Potentiometric Sensor (LAPS) for Analysis in Both Aqueous Solutions and Organic Solvents

Characteristics of a light-addressable potentiometric sensor (LAPS) based on silicon with Ta 2 O 5 dielectric are reported. The pH sensitivity obtained is 45 mV/pH unit in the pH range from 4.01 to 7.5 (for measurements conducted in citrate buffer solutions) and 55 mV/pH unit over the pH range from 7.5 to 8.9 (for measurements conducted in Tris-HCl buffer solutions). The kinetic characteristics (K m' V m' pH-profile) of different enzymes, i.e., glucose oxidase, α-chymotrypsin, butyrylcholinesterase, and urease, have been measured under homogeneous conditions. The values of the Michaelis constant obtained are very close to analogous data described in the literature. Biosensors were prepared by immobilization of the enzymes on a pH-sensitive matrix. Two methods of immobilization were used: incorporation into a hydrophilic matrix of bovine serum albumin (BSA) and incorporation into a hydrophobic matrix of modified polyethylenimine (PEI). It is demonstrated that LAPS can be used for recording the enzymatic reactions in organic media (mixture of the solvents).

Mechanism of the Benzophenone-Sensitized Photolysis ofO-Benzoyl-N-(1-naphthoyl)-N-phenylhydroxylamine in Cationic Micellar Media

The benzophenone-sensitized photolysis of the title hydroxylamine (1) in hexadecyltrimethylammonium chloride (HTAC) micelles was found to give benzoyloxy(2,3)- and phenyl(4,5)-migrated products, along with fragmentation products, 1-naphthanilide (6) and benzoic acid (7), which were obtained exclusively from the sensitized reaction in organic media. An analysis of the effects of added benzyl alcohol on the quantum yields for the reaction in HTAC micelles showed that the benzoyloxy-migrated products are derived from the amidyl-benzoyloxyl radical pair (that is present at the micellar surface), whereas the amidyl-phenyl radical pair (that is penetrated deeply into the micellar interior) is responsible for appearance of the phenyl-rearranged products. This effect of benzyl alcohol also confirmed that the hydrogen abstraction of the amidyl and benzoyloxyl radicals takes place in competition with the spin inversion of these triplet radicals. These interpretations were substantiated by the finding that the criti...

Causes of unreproducibility of C. rugosa lipase-catalyzed reactions in slightly hydrated organic media

Lipase activity, measured as hydrolysis of tributyrin is a valid assay to quantify the lipase activity of a lyophilized crude lipase in hydrolysis reactions but it is not useful to predict the catalytic activity in lipase-catalyzed reactions in organic media. Three factors control the catalytic activity in these media: i) relative proportion of isoenzymes; ii) amount of water in the lyophilized crude enzyme and iii) amount of lipase protein in the commercial powder. Thus we propose two simple reaction tests: i) heptyl oleate synthesis (specific of lipases), ii) enantioselective esterification of (R) or (S) 2-(3-benzoyl)phenyl propionic acid. This methodology is applied to different crude lipases of Candida rugosa, obtained in different fermenter conditions and shows the origin of the unreproducibility of the synthetic data.

Kinetics of enzymatic synthesis of isopropylidene glycerol esters by goat pregastric lipase

AbstractThe goat pregastric lipase‐catalyzed esterification of isopropylidene glycerol with caproic acid, to form isopropylidene glycerol caproate, followed a ping pong bi bi mechanism incorporating an acyl‐enzyme intermediate. The maximum rate was estimated to be 96 µmol min−1 mg−1 in isooctane at 35°C, and the Michaelis‐Menten constants for isopropylidene glycerol and caproic acid were 0.23 and 0.32 M, respectively. The catalyzed rate also correlated well with the partition coefficient of caproic acid between the organic and aqueous phases. The results suggest that the desolvation energy of the substrate from the bulk medium to the active site of the enzyme dominates the reaction rate for the enzyme‐catalyzed reaction in organic media.

Profiling of organic acids by capillary gas chromatography–mass spectrometry after direct methylation in urine using trimethyloxonium tetrafluoroborate

Trimethyloxonium tetrafluoroborate (TMO) is applied as derivatising reagent to transform urinary organic acids into their methyl esters. The method is suggested as an alternative to the use of diazomethane which is carcinogenic and explosive. In contrast to other methods avoiding diazomethane, such as derivatizations with acetyl chloride–methanol and boron trifluoride–methanol, which require an organic reaction medium and therefore an extraction of the organic acids from the urine, TMO efficiently reacts with the acids in an aqueous solution and can therefore be directly applied to native urine. The use of TMO simplifies and improves the sample preparation in the profile analysis of urinary organic acids by capillary GC–MS and hereby increases the speed of analysis. The method gives reproducible results which are comparable with the data obtained using conventional solid-phase extraction with strong anion-exchange cartridges prior to derivatisation.

ChemInform Abstract: Biocatalytic Reactions in Organic Media by Using Lipid‐Coated Enzymes

AbstractChemInform 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.

Multiple intensified performance of an enzyme-catalyzed reaction in organic medium.

A lipase-catalyzed glycerolysis reaction (a transesterification between polyunsaturated fatty acid ethyl ester [PUFA] and glycerol) was investigated. Its performance was multiply intensified by (1) using a lipase having high specific activity, high activity in organic solvent, and high tolerance in organic solvent; (2) immobilization on fine CaCO3 powder (cheap and safe material, easy physical adsorption method of immobilization, reusable); (3) reaction in vacuo resulting in 100% conversion and effective avoidance of oxidative deterioration of PUFA; (4) high volumetric productivity because of no use of solvent; and (5) no need of further separation and purification of the oil product. It is emphasized that performance of biocatalytic reactions in organic media should be enhanced manifold for industrial implementation.

Book Review: Enzymatic reactions in organic media, ed. A. M. P. Koskinen & A. M. Klibanov, Blackie Academic and Professional, London, 1996, xiii+314 pp., price UK£75.00. ISBN 0 7514 00259 1.

Pesticide ScienceVolume 54, Issue 1 p. 83-83 Book Review Book Review: Enzymatic reactions in organic media, ed. A. M. P. Koskinen & A. M. Klibanov, Blackie Academic and Professional, London, 1996, xiii+314 pp., price UK£75.00. ISBN 0 7514 00259 1. C. Bucke, C. BuckeSearch for more papers by this author C. Bucke, C. BuckeSearch for more papers by this author First published: 26 March 1999 https://doi.org/10.1002/(SICI)1096-9063(199809)54:1<83::AID-PS787>3.0.CO;2-UAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume54, Issue1September 1998Pages 83-83 RelatedInformation

Catalytic properties of novel reversed micellar system on trans-esterification by α-chymotrypsin in organic media

Novel reversed micelles formulated by sodium dioleylphosphate (SDOLP) has been developed for enzymatic reaction in organic media. Comparison study between sodium bis-(2-ethylhexyl)-sulfosuccinate (Aerosol-OT or AOT) and SDOLP, which was carried out by investigating the reactivity of each reversed micellar system as reaction media for enzymatic transesterification reaction of N-acetyl-1-phenylalanine ethyl ester (APEE) and 1-propanol, leads to the upshot that α-chymotrypsin immobilized within SDOLP reversed micelles can persevere its high catalytic activity in isooctane. The initial reaction rate of the SDOLP reversed micellar system is almost 60 times higher than that in the AOT system. Additional kinetic results, including the Michaelis constant and the maximum reaction rate, reveal that the inner core of the SDOLP reversed micelles provides a better environment for enzymatic reaction than that of the conventional AOT reversed micelles.

Microwave-promoted lipase-catalyzed reactions

Lipase from porcine pancreas is demonstrated to catalyze acylation reactions in organic media under microwave irradiation. Reaction rates and enantioselectivities are significantly enhanced 1–14 and 3–9 fold, respectively.

A Chiral Lewis-Acid-Catalyzed Diels−Alder Reaction. Water-Enhanced Enantioselectivity

A Chiral Lewis-Acid-Catalyzed Diels−Alder Reaction. Water-Enhanced Enantioselectivity

Book Review: Enzymatic reactions in organic media. Edited by A. M. P. Koskinen &amp; A. M. Klibanov, Blackie Academic &amp; Professional, Glasgow, 1995, xiii+314 pp., price UK£75.00. ISBN 0 7514 0259 1

Journal of Chemical Technology & BiotechnologyVolume 71, Issue 3 p. 275-275 Book Review Book Review: Enzymatic reactions in organic media. Edited by A. M. P. Koskinen & A. M. Klibanov, Blackie Academic & Professional, Glasgow, 1995, xiii+314 pp., price UK £75.00. ISBN 0 7514 0259 1 Peter Halling, Peter HallingSearch for more papers by this author Peter Halling, Peter HallingSearch for more papers by this author First published: 26 March 1999 https://doi.org/10.1002/(SICI)1097-4660(199803)71:3<275::AID-JCTB811>3.0.CO;2-0AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume71, Issue3March 1998Pages 275-275 RelatedInformation