Abstract: An acidic ionic liquid, namely (3-sulfonyl)propyltriethylamine hydrosulfate[HSO₃-(CH₂)₃N(C₂H₅)₃HSO₄ 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)₃CH₂SO₃HSO₄-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 10h. 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%.

Key words: α-pinene, acidic ionic liquid, esterification, catalysis