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In this paper, we describe the effectiveness of the combination between an organic solvent system mixture with orthoformates with different chain sizes from one to four carbon atoms. These orthoesters have been used as a "water trapper/alcohol releaser molecule" to reach a notable improvement in enantioselectivity and enantiomeric excess of our target compound, (S)-2-(4-isobutylphenyl)propanoic acid (ibuprofen eutomer), during the enzymatic kinetic resolution of rac-ibuprofen using immobilized lipase B of Candida antarctica as a biocatalyst. At the same time, one of the great problems of biocatalysis in organic media has been solved by eliminating excess water in the medium that allows the reversibility of the reaction. Following the optimization of the reaction conditions, an increase in enantiomeric excess and enantioselectivity was reached by using these acyl donors in the presence of a cosolvent. [ABSTRACT FROM AUTHOR]

In this paper, we describe the effectiveness of the combination between an organic solvent system mixture with orthoformates with different chain sizes from one to four carbon atoms. These orthoesters have been used as a “water trapper/alcohol releaser molecule” to reach a notable improvement in enantioselectivity and enantiomeric excess of our target compound, (S)-2-(4-isobutylphenyl)propanoic acid (ibuprofen eutomer), during the enzymatic kinetic resolution of rac-ibuprofen using immobilized lipase B of Candida antarctica as a biocatalyst. At the same time, one of the great problems of biocatalysis in organic media has been solved by eliminating excess water in the medium that allows the reversibility of the reaction. Following the optimization of the reaction conditions, an increase in enantiomeric excess and enantioselectivity was reached by using these acyl donors in the presence of a cosolvent.

As a byproduct of the physical refinement of crude palm oil, palm fatty acid distillate or PFAD has a potential to be transformed into monoglycerides by means of irreversible esterification with glycerol over a cation exchange resin catalyst. Irreversibility of the esterification can be assured by continuous azeotropic removal of water by adding xylene as an entrainer. Because PFAD-glycerol esterification demands high temperatures for fast conversion and high selectivity of monoglycerides, it is necessary to test catalyst reusability performance. In this research, evaluation of catalyst reusability performance was based on five parameters: free fatty acid conversion, the rate of free fatty acid decomposition, the selectivity of monoglycerides, monoglyceride concentration, and the cation exchange capacity of the catalyst. The cation exchange resin used was Tulsion T-42 SM. The evaluation was conducted using the simple multi-attribute rating technique extended to ranking (SMARTER) method. The results showed that the optimum reaction temperature was 180°C. Ultimately, a kinetic study at 180°C was also performed to model the reaction after using similar catalysts for certain times. This kinetic study revealed that the reaction mechanism changed from Langmuir-Hinshelwood to Eley-Rideal after several cycles of catalyst reuse.

Mathematical Model for Synthesis Reaction of Diacylglycerol by Irreversible Esterification Mechanism.Diacylglycerol, a component of natural oil has beneficial physiological function, mainly as oil with anti-obesity and antifat accumulation effect. Several studies for efficient synthesis of diacylglycerol have been done by researchers in Japan.Esterification of fatty acid and glycerol using biocatalyst has been used as an effective synthesis process on it wasindustrial scale. A kinetics model for diacylglycerol synthesis was proposed, however, it was very specific so that notappropriate to be applied in different condition. In this study, a model for diacylglycerol synthesis by stepwiseesterification of glycerol by fatty acid based on general assumption and condition is proposed. Runge-Kutta method isused in numerical calculation of substrate concentration. This model is useful for predicting behaviors of substrate atesterification of fatty acid and glycerol which is difficult to be measure experimentally, also as prediction in systemdesign for diacylglycerol synthesis at different scale.

Abstract: alpha-Linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been subjected to esterification with ethanol in presence of lipase B from Candida antarctica (Novozym 435®), in solvent free condition. The use of alcohol donors triethyl orthoformate (TEOF) or diethyl carbonate (DEC) instead of free ethanol, allowed working in irreversible esterification conditions and ALA-, EPA- and DHA-ethyl esters were obtained in quantitative yields. [Copyright &y& Elsevier]

A new irreversible esterification method for carboxylic acids catalyzed by a lipase from Candida antarctica (Novozyme 435) in organic solvents has been developed. The water produced during the process is chemically destroyed by a corresponding ester of acetoacetate, which acts as a sacrificial substrate in this reaction. The flavour esters isobutyl acetate, methyl butyrate, ethyl butyrate and benzyl butyrate were synthesized either in small scale (0.05 mol) or large scale (1 mol). The yields range from 82 to 92% within 24 h at 52°C. Optimal molar ratios of reactants were 1:1:1 (carboxylic acid:alcohol:acetoacetate). [ABSTRACT FROM AUTHOR]

Abstract: Dimethyl carbonate was used as alcohol donor in the esterification of naproxen in the presence of immobilised lipase B from Candida antarctica (Novozym 435). The conjugation of hydrolysis of dimethyl carbonate and esterification of acid, created irreversible operative conditions so permitting the recovery of S-naproxen in high ee (>98%). The adopted procedure has a general use. [Copyright &y& Elsevier]