Esterification lipase catalysed

Continuous lipase catalysed esterification of oleic acid... 

Lipase-catalysed esterification instead of ester hydrolysis is also being used, a.o. by Glaxo Wellcome for a kinetic resolution that yields (IS, 2. -tranx-2-methoxycyelo-... 

Lipase-catalysed esterification and transesterification reactions have a wide range of applications in the synthesis of aroma compounds. 

GeloPujic, M., Guibejampel, E., Loupy, A., Galema, S.A. and Mathe, D., Lipase-catalysed esterification of some alpha-D-glucopyranosides in dry media under focused microwave irradiation, /. Chem. Soc., Perkin Trans. 1, 1996, 2777. 

The enantioselective esterification of 2-arylpropionic acids catalysed by a lipase was discussed earlier.26 Steady-state kinetics of the Pseudomonas cepacia lipase-catalysed hydrolysis of five analogous chiral and achiral esters (R)- and (.S )-(235 R1 = Me, R2 = H), (R)- and (reaction mixtures of water-insoluble substrates.212 The Km values were all die same and the apparent kcat values reflected the binding abilities of the alcoholate ions for the fast-reacting enantiomers. All the substrates are believed to be... 

Marty, A. Chulalaksananukul, Condoret, J. S. Willemot, R. M. Durand, G. Comparison of Lipase-Catalysed Esterification in Supercritical Carbon Dioxide and in w-Hexane. Biotechnol. Lett. 1990, 12, 11-16. 

N. R. Pedersen, R. Wimmer, J. Emmersen, P. Degn, and L. H. Pedersen, Effect of fatty acid chain length on initial reaction rates and regioselectivity of lipase-catalysed esterification of disaccharides, Carbohydr. Res., 337 (2002) 1179-1184. 

Table 2.1 Lipase-catalysed esterification of 4,6-O-benzylidene glycopyranosides...

This method permits a clear distinction between a natural olive oil and an olive oil that has undergone esterification or inter-esterification processes, by determining the distribution of fatty acids on the three positions of glycerol. Lipases catalyse the following reactions ... 

Biocatalysts Ltd. Undated bulletin Lipase Catalysed Esterification"... 

Finally, an elegant example of a product derived from renewable raw materials is the bioemulsifier, marketed by Mitsubishi, which consists of a mixture of sucrose fatty acid esters. The product is prepared from two renewable raw materials - sucrose and a fatty acid - and is biodegradable. In the current process the reaction is catalysed by a mineral acid, which leads to a rather complex mixture of mono- and di-esters. Hence, a more selective enzymatic esterification (Fig. 1.43) would have obvious benefits. Lipase-catalysed acylation is possible [126] but reaction rates are very low. This is mainly owing to the fact that the reaction, for thermodynamic reasons, cannot be performed in water. On the other hand, sucrose is sparingly soluble in most organic solvents, thus necessitating a slurry process. 

B. Campou and A. N. Klibanov, Comparison of different strategies for the lipase-catalysed preparative resolution of racemic acids and alcohols Asymmetric hydrolysis esterification and transesterification. Biotech. Bioeng., 26 1449 (1984). 

Lipase-catalysed esterification of sucrose in [C4mim][dca] with decanoic acid was reported but not much information was given on conversions [116]. Enzymatic acylation of levoglucosan, an anhydro-sugar produced by pyrolysis of biomass, using Candida antarctica lipase in l-methoxyethyl-3-methylimidazolium dicyana-mide, gave 61% yield after 5 days at 50-60 °C [150],... 

Scheme 2. Kinetic resolution of racemic cyanohydrins by lipase catalysed hydrolysis and by lipase catalysed irreversible esterification with vinyl acetate...

Different ways of enhancing the solubility of polysaccharides in ionic liquids have been reported. Recently, ultrasound irradiation has been used to increase enzyme activity in lipase-catalysed esterifications of glucose with vinyl laurate or lauric acid in ILs [67]. It was found that ultrasound irradiation significantly enhances the enzyme activity probably due to an increase in the dissolution and mass transfer rates of substrates, without any loss in enzyme stability. 

Fig. 7.10 Lipase-catalysed enantioselective esterification of 2-substituted-propanoic adds with...

Athawale, V.D., and Gaonkar, S.R. (1994) Enzymatic synthesis of polyesters by lipase catalysed polytrans-esterification. Biotechnol. Lett., 16 (2), 149-154. 

Ducret A, Trani M, Lortie R (1998) Lipase catalysed enantioslective esterification of ibupiofen in organic solvent under controlled water activity. Enzyme Microb Technol 22 212—216 EUbol M, Ozer D (2001) Influence of oxygen transfer on Upase production by Rhizopus arrhizus. Proc Biochem 36 325-329... 

The mechanism of lipase-catalysed esterification or hydrolysis is shown in Scheme 4.1. The mechanism involves the formation of two tetrahedral intermediates, the first formed by nucleophilic attack of the serine residue of the catalytic triad onto the substrate. The tetrahedral intermediate loses water (R = H) or an alcohol (R H) to give an acyl enzyme complex that is either attacked by water (R = H) for hydrolysis or an alcohol (R H) for acylation. A second tetrahedral intermediate is formed that dissociates from the enzyme to give an ester or acid, thus regenerating the Hpase in its native form. Both of the tetrahedral intermediates involved in the mechanism are stabilized by hydrogen bonds to the oxyanion hole. 

An empirical rule was postulated by Jing and Kazlauskas to predict the enantiomer that reacts more quickly in a lipase-catalysed esterification reaction of a racemic secondary alcohol. The relative sizes of the two substituents determine the KR product [6]. X-ray structures of Upases revealed that the alcohol-binding pocket possesses a large hydrophobic pocket that is accessible to solvent along with a second, smaller pocket. The enantiopreference of lipases therefore allows for the determination of the absolute configuration of secondary alcohols. Clearly, the reliability of this method is dependent on how similar the molecule under study is to a molecule with a known absolute configuration in KR. The empirical rule to date only applies... 

From Achiral Non-carbohydrates. — 3-Deoxy-3-guanidino-D-threose 48 equilibrates with 49. a transition state inhibitor for galactosidase. It was synthesized as shown in Scheme 12 from epoxide 47, which was obtained by porcine pancreatic lipase catalysed enantioselective esterification of the racemic epoxy-alcohol precursor. 6-Deoxy-L-talonolactone 50 was synthesized by an asymmetric aldol condensation - dihydroxylation sequence (Vol.24, p.lS2) in improved diastereoselectivity and was converted into 2-acetamido-2,6-dideoxy-L-fucose (shown as its furanose isomer 51 in Scheme 13), 3-acetamido-3,6Hlideoxy-L-idose and 5-acetamido-S,6-dideoxy-D-allose by S 2 displacements of triflate with azide ion. 4-Amino-4-deoxy-DL-erthrose 53 was obtained from the hetero-Diels-Alder adduct 52 by a sequence of reactions including cis-dihydroxylation (OSO4, NMNO) of the alkene moiety (Scheme 14). The synthesis of a racemic branched-chain lactam is covered in Chapter 16. 

Syed Rahmatullah, M.S.K. Shukla, V.K.S. Mukherjee, K.D. y-Linolenic acid concentrates from borage and evening primrose oil via lipase catalysed esterification. J. Am. Oil Chem. Soc. 1994, 71, 563—567. 

The direct lipase catalysed esterification process for fiavours has been described by Iwai and Tsujusaka (1984) and by Lazar etal. (1986) for producing geranyl butyrate and black current (2-methyl-pentanylolprenylester) flavours, respectively. The process by Lazar et al. (1986) circumvents the inherent problem of flavour impairment (Schmid, 1987) associated with chemical synthesis of the flavour. 

---