Synthesis of Terpineol from Alpha-Pinene Catalyzed by α-Hydroxy Acids
2022
Zhong-Lei Meng | Ru-Si Wen | Xiao-Rui Huang | Rong-Xiu Qin | Yi-Ming Hu | Yong-Hong Zhou
We report the use of five alpha-hydroxy acids (citric, tartaric, mandelic, lactic and glycolic acids) as catalysts in the synthesis of terpineol from alpha-pinene. The study found that the hydration rate of pinene was slow when only catalyzed by alpha-hydroxyl acids. Ternary composite catalysts, composed of AHAs, phosphoric acid, and acetic acid, had a good catalytic performance. The reaction step was hydrolysis of the intermediate terpinyl acetate, which yielded terpineol. The optimal reaction conditions were as follows: alpha-pinene, acetic acid, water, citric acid, and phosphoric acid, at a mass ratio of 1:2.5:1:(0.1&ndash:0.05):0.05, a reaction temperature of 70 °:C, and a reaction time of 12&ndash:15 h. The conversion of alpha-pinene was 96%, the content of alpha-terpineol was 46.9%, and the selectivity of alpha-terpineol was 48.1%. In addition, the catalytic performance of monolayer graphene oxide and its composite catalyst with citric acid was studied, with acetic acid used as an additive.
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