An Unprecedented Effective Enzymatic Carboxylation of Phenols

It is well-known that the equilibrium of the enzymatic Kolbe-Schmitt reaction is unfavorable for the carboxylation direction. A new method was developed to push the reaction equilibrium toward the carboxylation of resorcinol and catechol by adding quaternary ammonium salts into the reaction system. The yields of the carboxylation products were increased up to 97% from less than 40%. The precipitation capacity of the quaternary ammonium salts of the carboxylic acid products is the driving force for the reaction equilibrium shift. Therefore, effective enzymatic carboxylation of phenols has been achieved for the first time.