Synthesis of cresotic acids by carboxylation of cresols with sodium ethyl carbonate

Abstract

Carboxylation of o-cresol, m-cresol, and p-cresol with sodium ethyl carbonate (SEC) proceeds regioselectively with the formation of cresotic acids: 2-hydroxy-3-methylbenzoic acid, 2-hydroxy-4-methylbenzoic acid, and 2-hydroxy-5-methylbenzoic acid, respectively. Optimal conditions for conducting the process have been found to be as follows: the reactants ratio of [cresol]: [sodium ethyl carbonate] = (1.5–2): 1, T = 180–185°C, \({P_{C{O_2}}}\) = 10 atm, and t = 6–7 h. Simple and convenient methods for the synthesis of cresotic acids, which can be used for their industrial manufacturing, have been developed.