The Influence of Organic Medium and Supports in the Resolution of (R,S)-Menthol Catalyzed by Lipases

Abstract

In this study, various commercial and native lipases, free or immobilized, were used in the enantioselective resolution of (R,S)-menthol with vinyl acetate for the preparation of menthyl acetate. Lipase from Candida rugosa (AYL) was found to be the most appropriate. When the reaction was carried out at 35 °C, using 40 mg of AYL and a molar ratio of 1:2 (alcohol:ester), the values for the conversion degree, the enantiomeric excess of the substrate (ee s ) and product (ee p ) and the enantiomeric ratio (E) were 33.6, 50.3, > 99% and > 200, respectively. The results showed that the reaction was more efficient using toluene in comparison with other organic solvents or mixtures of toluene and ionic liquids (ILs). The best support for the AYL immobilization, was corn starch film. This system was used 4 times over 71 days of storage, and menthyl acetate was still obtained with good values of conversion degree, ee s , ee p , and E.

Recent Trends in Biomaterials for Immobilization of Lipases for Application in Non-Conventional Media

“…The biocatalyst was applied in the enantioselective resolution of (R,S)-menthol using vinyl acetate as the acyl donor (Figure 15), with toluene as the solvent at 35°C. The conversion of (R)-menthol to (R)-menthyl acetate ester was 33%, with an enantiomeric excess of product of greater than 99% after 48 h [92].…”

“…After optimization of the reaction conditions, the conversion was greater than 99% after 24 h at 25 • C for two different reactions in different media: (i) the synthesis of 1-octyl acetate using neat methyl tert-butyl ether (MTBE) and also using diethyl ether/[BMIM][PF 6 ] (9:1), and (ii) the synthesis of 1-pentyl octanoate using diethyl ether/[BMIM][Cl] (9:1) [89]. Corn starch films were also prepared and used to immobilize CRL by entrapment [92]. The biocatalyst was applied in the enantioselective resolution of (R,S)-menthol using vinyl acetate as the acyl donor (Figure 15), with toluene as the solvent at 35 • C. The conversion of (R)-menthol to (R)-menthyl acetate ester was 33%, with an enantiomeric excess of product of greater than 99% after 48 h [92].…”

“…Corn starch films were also prepared and used to immobilize CRL by entrapment [92]. The biocatalyst was applied in the enantioselective resolution of (R,S)-menthol using vinyl acetate as the acyl donor (Figure 15), with toluene as the solvent at 35 • C. The conversion of (R)-menthol to (R)-menthyl acetate ester was 33%, with an enantiomeric excess of product of greater than 99% after 48 h [92]. Some structural properties of starch can be modified to meet specific requirements [93].…”

Convenient enzymatic resolution of (R,S)‐2‐methylbutyric acid catalyzed by immobilized lipases

“…Enantiopure alcohols, amines, and carboxylic acids are key compounds for the synthesis of many fine‐chemistry derivatives, such as pharmaceuticals, agrochemicals, and pheromones . In particular, steriochemically pure carboxylic acids are extremely useful building blocks, being easily converted into many of the other functional groups.…”

Easy and Simple SiO2 Immobilization of Lipozyme CaLB-L: Its Use as a Catalyst in Acylation Reactions and Comparison with Other Lipases

“…15 In this context, commercially available silica gel could represent a cheap and easy support to improve the performance of lipases. In this study, we explored a simple methodology for the immobilization of Lipozyme CaLB-L on SiO 2 without the need of controlled pH and longer periods of contact between the support and enzyme, as it is usually reported in the literature, 5,16,17 providing a catalyst to be used right away. Among the advantages by the usage of this support is that SiO 2 is highly resistant to the organic media and has a high capacity in adsorption.…”