Abstract:

A acidic ionic liquid [MIMPS]HSO4 was synthesized and used for the esterification of salicylic acid. Factors including reaction temperature, reaction time, ratio of reactant and amount of ionic liquid were investigated. It was found that the optimized conditions were at 95 ℃, microwave irradiation for 20 min, molar ratio of methanol to salicylic acid with 3∶1, amount of [MIMPS]HSO4 10 mmol. The yield and selectivity of methyl salicylate were 91.9% and 99.0% respectively. [MIMPS][HSO4] as a catalyst can be recycled for 4-times without obvious decrease in activity. Microwave irradiation could reduce reaction time under the same conditions. The yield of esterification decreased as the carbon chain increases, and also when the secondary alcohols were used instead of the primary alcohols.

Key words: microwave, acidic ionic liquids, esterification, methyl salicylate