Esterification of α-pinene and acetic acid using acidic ionic liquids as catalysts

The direct esterification of α-pinene and acetic acid was investigated in the presence of acidic ionic liquids (ILs). The results show that acidic ILs, (3-sulfonic acid)-propyltriethylamine hydrosulfate ([HSO3–(CH2)3–NEt3]HSO4) and (3-sulfonic acid)propyltriethylamine dihydrogen phosphate ([HSO3–(CH2)3–NEt3]H2PO4), were of good catalytic property. The product could be easily separated from the reaction mixture and the ILs catalysts were of good reusability. Hence, a clean and environmentally friendly strategy for synthesizing bornyl acetate and α-terpinyl acetate is provided.