Synthesis of methyl salicylate over nano-crystalline sulfated-zirconia

Salicylates in its derivatized forms are widely used in medicine [1]. Methyl salicylate is a typical molecule having an intramolecular hydrogen bond between its hydroxyl and carbonyl groups [2]. Methyl salicylate (oil of wintergreen) is used for relieving muscle aches and pains by applying externally to the affected area. It is an ingradient in numerous commercially available products [3]. Methyl salicylate is an important chemical compounds. It is a fragrance ingredient used in many fragrance compounds. It may be found in fragrances used in decorative cosmetics, fine fragrances, shampoos, toilet soaps and other toiletries as well as in non-cosmetic products such as household cleaners and detergents.The present investigation is aimed to find out the catalytic activity and the effect of sulfated zirconia in a reaction between methanol and salicylic acid to synthesize methyl salicylate. Here we report that the sulfated zirconia exhibit good catalytic activity in the esterification reaction between salicylic acid and methanol. The results obtained are very encouraging in the sense that solid acids not only show selectivity but also high activity towards the formation of methyl salicylate.Methyl salicylate can be prepared by simple esterification of salicylic acid with methanol in presence of a solid acid catalyst. These solid acids are known to possess on their surface moisture-sensitive active sites, which get poisoned by water molecules produced during the direct esterification reaction between an alcohol and the acid thus decreasing the yield of the product and the life time of the solid acid catalysts.In continuation of our recent work on the use of solid acid catalysts [4], we now wish to introduce sulfated zirconia as effective catalysts for the esterification of salicylic under mild reaction conditions