Green esterification: the synthesis of aromas in the presence of an acid resin.

Abstract

Synthesis of aromas by esterification of a carboxylic acid (acetic and butanoic acid) with an alcohol (methanol, ethanol, pentanol) has been carried out in the presence of strong homogeneous acid catalysts (e.g. sulphuric acid, hydrochloric acid). However, these mineral acids are corrosive and they are usually neutralised after reaction (with consequent salt formation). In order to overcome the above-mentioned problems, different solid acid catalysts (heterogeneous catalysts) have been used in esterification reactions. The use of heterogeneous catalysts for these reactions is preferable as they can be easily separated from the reactants and products by filtration and it can be reused after reaction, becoming a more environmental friendly method. In this context, it is proposed the synthesis of aromas’ fruits over a solid commercial catalyst. Their separation and spectroscopic characterization by IR and NMR is carry out. Moreover, the experiment is suitable to the determination of catalytic activity and stability of the resin. This activity could be also applied as a “Green Synthesis” experiment in laboratory classroom.