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1.
Effect of acyl donor chain length and sugar/acyl donor molar ratio on enzymatic synthesis of fatty acid fructose esters 总被引:3,自引:0,他引:3
Samia Soultani Jean-Marc Engasser Mohamed Ghoul 《Journal of Molecular Catalysis .B, Enzymatic》2001,11(4-6):725-731
Lipase-catalyzed synthesis of fatty acid sugar esters through direct esterification was performed in 2-methyl 2-butanol as solvent. Fructose and saturated fatty acids were used as substrates and the reaction was catalyzed by immobilized Candida antarctica lipase. The effect of the initial fructose/acyl donor molar ratio and the carbon-chain length of the acyl donor as well as their reciprocal interactions on the reaction performance were investigated. For this purpose, an experimental design taking into account variations of the molar ratio (from 1:1 to 1:5) and the carbon-chain length of the fatty acid (from C8 to C18) was employed. Statistical analysis of the data indicated that the two factors as well as their interactions had significant effects on the sugar esters synthesis. The obtained results showed that whatever the molar ratio used, the highest concentration (73 g l−1), fructose and fatty acid conversion yields (100% and 80%, respectively) and initial reaction rate (40 g l−1 h−1) were reached when using the C18 fatty acid as acyl donor. Low molar ratios gave the best fatty acid conversion yields and initial reaction rates, whereas the best total sugar ester concentrations and fructose conversion yields were obtained for high molar ratios. 相似文献
2.
By using lipase PS-30 as catalyst, the kinetic resolution of a series of racemic propargylic alcohols has been achieved via stereoselective acylation. The value of kinetic enantiomeric ratio (E) reached up to 139. Substituent effect is briefly discussed. 相似文献
3.
《Chirality》2017,29(12):798-810
Enantiomerically pure secondary alcohols are essential compounds in organic synthesis and are used as chiral auxiliaries and synthetic intermediates in the pharmaceutical, agrochemical, and fine chemical industries. One of the attractive and practical approaches to achieving optically pure secondary alcohols is oxidative kinetic resolution of racemic secondary alcohols using chiral Mn(III) salen complexes. In the last decade, several chiral Mn(III) salen complexes have been reported with excellent enantioselectivity and activity in the homogeneous and heterogeneous catalysis of the oxidative kinetic resolution of racemic secondary alcohols. This review article is an overview of the literature on the recent development of chiral Mn(III) salen complexes for oxidative kinetic resolution of racemic secondary alcohols. The catalytic activity of monomeric, dimeric, macrocyclic, polymeric, and silica/resin supported chiral Mn(III) salen complexes is discussed in detail. 相似文献
4.
Chiral polymeric Mn(III) salen complexes were used efficiently for oxidative kinetic resolution of racemic secondary alcohols at room temperature. High chiral purity (ee; >99%) was achieved for the oxidative kinetic resolution of racemic secondary alcohols with 0.6 mol % catalyst loading in 60 min. The catalyst was easily recycled for five successive catalytic experiments. 相似文献
5.
Yewang Zhang Dongzhi Wei Dengchao Li Shulai Liu Qingxun Song 《Biocatalysis and Biotransformation》2007,25(1):59-64
Enzymatic synthesis of cefaclor by penicillin acylase (PA) was carried out under kinetic control with in situ product removal (ISPR). We present a continuous acyl donor feeding strategy for enzymatic reactions. Using this strategy, the conversion of the antibiotic nucleus was improved from 65 to 91%, and the hydrolysis of phenylglycine methyl ester (PGME) was decreased. Side product (phenylglycine) production was less than half of that in the control batch. The ratio of synthesis to hydrolysis (S/H) in the process was kept stable for longer and at a higher level than in the control. This is a practical method for enzymatic synthesis of cefaclor. 相似文献
6.
Yewang Zhang Dengchao Li Shulai Liu Qingxun Song 《Biocatalysis and Biotransformation》2013,31(1):59-64
Enzymatic synthesis of cefaclor by penicillin acylase (PA) was carried out under kinetic control with in situ product removal (ISPR). We present a continuous acyl donor feeding strategy for enzymatic reactions. Using this strategy, the conversion of the antibiotic nucleus was improved from 65 to 91%, and the hydrolysis of phenylglycine methyl ester (PGME) was decreased. Side product (phenylglycine) production was less than half of that in the control batch. The ratio of synthesis to hydrolysis (S/H) in the process was kept stable for longer and at a higher level than in the control. This is a practical method for enzymatic synthesis of cefaclor. 相似文献
7.
Wheat germ lipase catalyzed kinetic resolution of secondary alcohols in non-aqueous media 总被引:1,自引:0,他引:1
The lipase from wheat germ was used for the kinetic resolution of secondary alcohols. It has the opposite enantioselectivity
against the Kazlauskas rule and acts as an anti-Kazlauskas catalyst. The effect of initial water activity, organic solvent,
acyl donor and temperature were investigated. Wheat germ lipase had a high activity and enantioselectivity only in n-hexane with a high initial water activity (αw = 0.97), especially with 1-phenylethanol (C 32%, E > 200). Its performance changed little with the chain length of acyl donor and temperature.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
8.
为了提高脂肪酶在非水相中对手性仲醇的拆分效率,以2-辛醇为模式底物,建立了以辛酸为酰基供体的无溶剂脂肪酶动力学拆分手性仲醇的反应体系,采用1.5∶1的酸醇摩尔比,45℃条件下反应12 h,2-辛醇的转化率达到49.9%,并且S-2-辛醇的对映体过量率e.e.s=98.2%,反应的对映体比率E600。利用脂肪族仲醇与水形成共沸物的特性,通过非均相共沸蒸馏的方法提取拆分得到的手性仲醇,S-2-辛醇的光学纯度并未降低,并且产率大于90%,产品纯度大于98%。 相似文献
9.
Candida rugosa lipase-catalyzed esterification of ibuprofen with 1-propanol was conducted in seven ionic liquids and the results were compared with those in isooctane. Although the enzyme showed comparable or higher activity in some ionic liquids compared to that in isooctane, only in the case of [BMIM]PF6 was the enantioselectivity (E = 24.1) almost twice that (E = 13.0) of isooctane. In another six ionic liquids the enzyme enantioselectivity was much poorer (E = 1.1-6.4). At the same conversion of 30%, E of [BMIM]PF6 is more than triple that of isooctane. The lipase stability in [BMIM]PF6 was improved by 25% of that in isooctane. It was concluded that [BMIM]PF6 could be applied to substitute the conventional organic solvent (isooctane) in the esterification of ibuprofen. 相似文献