Novelty of immobilized enzymatic synthesis of 3-ethyl-1,3-oxazolidin-2-one using 2-aminoalcohol and dimethyl carbonate: mechanism and kinetic modeling of consecutive reactions

Abstract

Oxazolidinones are multifunctional compounds possessing diverse biological and pharmacological activity. Enzymatic synthesis of oxazolidin-2-one was studied using 2-aminoalochol and dimethyl carbonate and synthesis of 3-ethyl-1,3-oxazolidin-2-one was chosen as the model reaction using a variety of immobilized lipases; among which Candida antarctica lipase B (Novozyme 435) was the best catalyst. The reaction leads to the final product oxazolidin-2-one via methyl ethyl (2-hydroxyethyl) carbamate as the intermediate. The parameters affecting rate of reaction and the conversion of both steps were studied systematically and covered effects of agitation speed, solvent, catalyst loading and reaction temperature. A reaction mechanism was proposed wherein the coproduct methanol is generated in the first step leading to the formation of methyl ethyl (2-hydroxyethyl) carbamate as the intermediate which rearranges itself leading to the final products 3-ethyl-1,3-oxazolidin-2-one and methanol. The kinetic constant and activation energy were determined for each step of the reaction. The study was further extended to other 2-aminoalochols under optimized reaction conditions to prepare different oxazolidinones. This is a first report of its kind describing kinetics and mechanism of bimolecular consecutive enzyme catalyzed reactions.