Transesterification of methyl salicylate with isoamyl alcohol assisted by microwave irradiation and promoted by acid-basic catalysts

Abstract

A procedure was studied for synthesising isoamyl salicylate by transesterifying methyl salicylate with isoamyl alcohol. The transesterification reaction was evaluated using catalysts with different acid-base properties in microwave irradiation or conventional heating. The amounts of methyl salicylate and isoamyl salicylate in samples were analysed by Gas Chromatography. Acids and neutral catalysts showed zero or shallow catalytic activity, while the most actives were the basic catalysts. Methyl salicylate conversions (higher than 60%) were obtained at 120°C in 4 h of reaction under the Microwave irradiation procedure, using 1% wt. Ca(OH)2, MeONa, or LiOH as catalysts. Under these optimised conditions, using LiOH as a catalyst, it could obtain yields of isoamyl salicylate of 98% in 4 h. Finally, under experimental conditions of isoamyl salicylate synthesis, LiOH did not present catalytic homogeneous contribution.