Catalysed or uncatalysed esterification reaction of oleic acid with 2-ethyl hexanol

The para-toluene sulfonic acid (p-TSA) catalysed and uncatalysed esterifications between oleic acid and 2-ethylhexanol are investigated. The reactions were carried out in the presence of the stoichiometric amount or twice the stoichiometric amount of alcohol with respect to the fatty acid, at 140-170 degreesC. In the presence of 1% of solid p-TSA monohydrate in xylene, the reaction is completed in 50 min at 140 degreesC. Without xylene, a mass concentration of esters of 93% is then reached after 10 min of reaction in the concentrated alcoholic medium containing 1% of p-TSA. Without added catalyst, the kinetic is fast and the reaction is completed in 280 min at 170 degreesC in the concentrated alcoholic medium. The reactive molecules and the products of the reaction are organised in hydrophilic aggregates in the concentrated oleophobic medium. The carboxylic group of the fatty acid is then activated and shows a high catalytic activity. (C) 2000 Elsevier Science B.V. All rights reserved.