Homogeneous catalytic esterification of glycerol with cinnamic and methoxycinnamic acids to cinnamate glycerides in solventless medium: Kinetic modeling

Abstract

Abstract The homogeneous catalytic processes of the esterification of glycerol with cinnamic and p-methoxycinnamic acids in the absence of organic solvents to obtain mainly monocinnamoyl glycerols using PTSA as catalyst were studied. Esterification runs were performed batchwise, changing the initial molar ratio of acid to glycerol from 1:3 to 1:9, and the temperature from 140 to 160 °C for cinnamic acid and from 150 to 170 °C in the case of the esterification with methoxycinnamic acid. Under such conditions, almost quantitative acid conversion was obtained and selectivity to monoglyceride was very high. Previous runs and kinetic modeling suggest a first-order deactivation of the catalyst and the presence of two consecutive esterification reactions for both acids: one to produce monoglyceride from acid and glycerol and the other to obtain diglycerides from the monoester and phenolic acid. Finally, kinetics models for both acid esterifications in acid-catalyzed and autocatalytic esterifications are compared.