Synthesis of terpinyl acetate catalyzed by acidic functional polyether ionic liquid

An acidic functional polyether ionic liquid,1-(3-sulfonic group)propyl-3-polyoxyethyleneimidazole dihydrogen phosphate([HSO3-(CH2)3-im-(CH2CH2O)nH]H2PO4),was synthesized and used to catalyze the esterification of terpineol with acetic anhydride.The effects of reaction condition,i.e.,reaction temperature,reaction time,n(terpineol)∶n(acetic anhydride) and amount of acidic functional ionic liquid,were investigated.The optimum condition for the 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 ℃,reaction time 8 h.Terpineol conversion of over 99.5% and selectivity to terpinyl acetate of 87.8 % were obtained under the optimum condition.Recyclability of the ionic liquid was also investigated.Terpineol conversion of 99.4% and the selectivity to terpinyl acetate of 88.3% were attainable after the ionic liquid was used for six times.