Research Into Esterification of Mixture of Lower Dicarboxylic Acids by 2-ethylhexan-1-ol in the Presence of P-toluensulfonic Acid

Abstract

Regularities of esterification of the mixture of lower dicarboxylic acids (succinic, glutaric, adipic) by 2-ethylhexan-1-ol in the presence of catalysts – p-toluensulfonic and sulfuric acids under non-stationary conditions were studied. It was found that in the presence of mineral acid, the reaction flows at a lower rate. Application of benzene as a substance that facilitates separation of water, formed in the esterification reaction, makes it possible, due to a lower reaction temperature, to decrease energy consumption of the process at an increase in conversion of dicarboxylic acids from 95.8 to 99.5 %. It was shown that the use of activated carbon of different brands simultaneously with catalysis by p-toluensulfonic acid with virtually the same effectiveness can decrease chromaticity intensity of esterification products by more than three times. The use of finely dispersed activated carbon 208CP and DCL 200 compared with coarse-grained activated carbon BAU-A additionally provides higher intensity of esterification reaction due to improvement of removal of water from the reaction mixture. It was found that an increase in the content of activated carbon DLC 200 by more than 0.3 % by weight in the reaction mixture contributes to a sharp decrease in the process intensity. This influence is explained by neutralization of a part of the catalysts by alkaline components of activated carbon, which decreases its active concentration and inhibits the reaction. Optimum conditions of the esterification process were proposed. The authors determined dependences of density and kinematic viscosity of the mixture of diesters of succinic, glutaric and adipic acids, and 2-ethylhexan-1-ol, separated from the esterification reaction products, on temperature and described them with regression equation