Lipase‐catalyzed esterification of lactic acid with straight‐chain alcohols

Enzymatic synthesis of esters of lactic acid and straight‐chain alcohols with different chain lengths (C 6 –C 18 ) were investigated in batch reactions with hexadecanol (C 16 ) as the model alcohol. Cyclohexane was the best solvent for higher ester yields, and the best biocatalyst was the immobilized Candida antarctica lipase B (Novozym 435) as well as the textile‐immobilized Candida sp. lipase. A method was established to obtain ester yields in the range of 71 to 82% for the different alcohols, and the most favorable conditions for the esterification reaction using Novozym 435 were an equimolar ratio of lactic acid to alcohol, each at a concentration of 120 mM each; a 50°C reaction temperature; 190 rpm shaking speed; and the addition of 100 mg molecular sieves (4 Å) for drying. The ester yield increased with increasing lipase load, and a yield of 79.2% could be obtained after 24 h of reaction at 20 wt% of Novozym 435. The immobilized Candida sp. lipase prepared in the laboratory also could be used to produce esters of lactic acid and straight‐chain alcohols, but it had a much lower activity than Novozym 435 with a temperature optimum of 40°C.