Synthesis of Bornyl Acetate from α-Pinene Catalyzed by Acidic Ionic Liquid

An acidic ionic liquid,namely(3-sulfonyl)propyltriethylamine hydrosulfate[HSO3-(CH2)3N(C2H5)3]HSO4 was prepared and characterized by FT-IR,1H NMR and 13C NMR.Esterification of α-pinene catalyzed over the composite catalytic system of [N(Et)3(CH2)3SO3H]HSO4-ClCH2COOH was studied.The influences of reaction factors,such as amount of acidic ionic liquid,reaction temperature,reaction time and proportion of reactants were investigated.The optimum conditions for α-pinene esterification were obtained as follows:n(α-pinene)∶n[N(Et)3(CH2)3SO3H]HSO4∶n(chloroacetic acid)∶n(acetic acid) 5∶0.6∶5∶14,reaction temperature 30 ℃,reaction time 10 h.Under the above conditions,the conversion of α-pinene was 95.90 % and the selectivity of bornyl ester was 45.07 %.The reusability of the composite catalytic system was investigated.Under the optimum conditions,when the composite catalytic system was repeatedly used for 5 times,α-pinene conversion reached 87.4 % and the selectivity of bornyl ester was 40.6 %.