Method for lipase-catalyzed carbonate synthesis via one- and two-step alkoxycarbonylation reactions

Lipase-catalyzed alkoxycarbonylation methods offer potential advantages over the currently practiced industrial scale chemical synthesis of carbonates. We report a method for synthesis of organic carbonates via lipase-catalyzed alkoxycarbonylation between diphenyl carbonate and various alcohols in hexane. This method utilizes precursors that are readily available and does not involve extensive purification of the intermediate. In a two-step process, the two phenyl groups of diphenyl carbonate were substituted by two alcohol nucleophiles. The approach was demonstrated for two-step synthesis of 14 different disubstituted carbonate products. The rates of reaction for the two steps were much slower if the order of nucleophile addition was reversed. Under optimal conditions, complete conversion of diphenyl carbonate occurred within 8-15 h at 50 degrees C, which is a significant improvement from 50-90 h at 24 degrees C. A kinetic model for the alkoxycarbonylation reaction was derived based on the Michaelis-Menten equation, which simplified to first-order kinetics at low and equimolar concentration of substrates.