Selectivity of R-α-monobenzoate glycerol synthesis catalyzed by Candida antarctica lipase B immobilized on heterofunctional supports

• The stereoselectivity of CALB was modified by the support and its functionalization.
• Heterofunctional silica allowed obtaining the most stereoselective biocatalyst.
• Silica biocatalysts were the most active and stable in organic solvents.

The main goal of this work was to study different strategies of immobilization of Candida antarctica lipase B (CALB) in order to evaluate changes in the selectivity of this enzyme when R-α-monobenzoate glycerol (R-α-MBG) is obtained through of asymmetric esterification. CALB was immobilized on sepharose and silica functionalized with octyl groups (monofunctional supports) and undecanol–glyoxyl and octyl-epoxide groups (heterofunctional supports). Our results showed that the enzyme could be immobilized by all carriers, with activity yields ranging from 52% to 83%. CALB immobilized on silica octyl was the most active (367 IU g−1biocatalyst) with immobilization yields in terms of protein and expressed activity of 72% and 50% respectively and exhibited a higher half-life in 100% 1,4-dioxane at 50 °C (85,000 h). In contrast, CALB immobilized on heterofunctional silica support was the most selective biocatalyst, reaching an enantiomeric excess of 99% of R-α-MBG in 100% 1,4-dioxane. In terms of configuration the sepharose biocatalysts results in a S-enantiomer, while silica biocatalysts results in a R-enantiomer. The catalysis of asymmetric esterification of glycerol with benzoic acid to obtain R-α-MBG by CALB immobilized in heterofunctional silica is highly selective and, to our knowledge, is the most selective reported to date.

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