Synthesis of methyl laurate catalyzed by bronsted acid ionic liquids

Benyong Han, Wudi Zhang, Yubao

Abstract

Ionic liquids as environmentally benign chemical solvent, had been used in diverse chemical reactions, because they have many advantages, such as non-corrosion, non-toxic, non-volatile, anti-oxidize, wide temperature range, good stability, high catalytic activity. Two kinds of Brønsted ionic liquids 1-methylimidazolium hydrogen sulfate ([Hmim]HSO4) and 1-methyl-2-pyrrolidonium hydrogen sulfate ([Hnmp]HSO4) were prepared. Synthesis of methyl laurate from lauric acid catalyzed by the ionic liquid was studied. Effects of ionic liquid dosage, molar ratio between methanol and lauric acid, reaction temperature and reaction time on the esterification reaction and stability of the ionic liquid were investigated. Optimal esterification condition was obtained as follows: n(methanol): n(lauric acid) = 6: 1, reaction temperature 70℃, reaction time 2 h, dosage of ionic liquid = 5 % of the lauric acid weight. The yield of methyl laurate reached 97.41％ without removal of water during the esterificaion. The ionic liquid was stable and could be repeatedly used.