Synthesis of Terpinyl Acetate Catalyzed by Acidic Functional Ionic Liquid Sulfonic Alkylimidazole Phosphate

An acidic functional ionic liquid 1-(3-sulfonic group)propyl-3-methylimidazole dihydrogen phosphate((HSO3-pmim) H2PO4) was synthesized and used to catalyze the esterification of terpineol with acetic anhydride.The influences of reaction condition,such as reaction temperature,reaction time,n(terpineol)∶n(acetic anhydride) and amount of acidic functional ionic liquid were examined.The optimum condition for esterification was obtained as follows:n(terpineol)∶n(acetic anhydride)1∶1.5,terpineol 5.1 g,ionic liquid 1.5 g,reaction temperature 40 ℃ and reaction time 8 h.Under the above condition,the conversion of terpineol was 100 % and the selectivity of terpinyl acetate was 87.2 %.The recyclability of the ionic liquid was also investigated.When the ionic liquid was repeatedly used for six times,the conversion of terpineol was 99.4 %,and the selectivity of terpinyl acetate was 88.6 %.The catalyst for this synthesis has advantages of high yield,simple experimental operation and product isolation,and easy reusability of the catalyst which could be expected to realize an clean and environment-friendly strategy for the production of terpinyl acetate.