Synthesis of fruity flavor esters: An experiment for undergraduate courses within one of the principles of green chemistry

Abstract

The esters are among the classes of organic substances responsible for the pleasant odor of flowers and fruits. The synthesis of these substances occurs through the reaction between carboxylic acids and alcohols, usually catalyzed by Brensted-Lowry acid. This work presents the results of different methods of esterification using homogeneous catalysis like sulfuric acid and heterogeneous catalysis with commercial sulfonic resin (Amberlyst 35) and montmorilonite clay. All reactions were carried out with heating under reflux and repeated with use of the system Dean-Stark to remove water produced in the reaction. The use of Dean-Stark moves the equilibrium to the formation of the products and, consequently, reduces significantly the reaction time. The heterogeneous catalysts proved to be advantageous relatively to the use of sulfuric acid since the process of isolation is easier and provides an approach of Green Chemistry in Undergraduate experimental classes.