钛酸异丙酯催化脱氢芳樟醇合成柠檬醛

以钛酸异丙酯为主催化剂,氯化亚铜为助催化剂,在氮气保护和有机酸的存在下,研究了脱氢芳樟醇经迈耶－舒斯特重排反应合成柠檬醛.优化的反应条件如下:n(钛酸异丙酯):n(氯化亚铜)=4:1,催化剂(钛酸异丙酯+氯化亚铜)和对甲基苯甲酸的用量分别为原料脱氢芳樟醇质量的3.5%和10%,在110℃下反应3h,得到脱氢芳樟醇的转化率为98.8%,生成柠檬醛的收率为88.4%.采用水蒸气蒸馏的方法分离反应液,得到纯度≥97%的柠檬醛,采用FTIR对产物进行表征,确定了产品柠檬醛中所含有的主要杂质.最后,探讨了脱氢芳樟醇合成柠檬醛的反应机理.

Synthesis of citral from dehydrolinalool catalyzed by titanium isopropylate

With titanium isopropylate as the primary catalyst and cuprous chloride as promoter, citral was synthesized from dehydrolinalool through Meyer-Schuster rearrangement in the presence of organic acid under nitrogen atmosphere. The optimized conditions were as follow:n(titanium isopropylate):n(cuprous chloride) was 4:1, the dosage of catalyst (titanium isopropylate + cuprous chloride) was 3.5% of dehydrolinalool, the amount of 4-methylbenzoic acid was 10% of dehydrolinalool, the reaction was operated at 110℃ for 3h. The conversion of dehydrolinalool was 98.8% and the yield of citral was 88.4%. Citral with purity of ≥97% was separated from reaction mixtures by steam distillation. The product was characterized by means of FTIR and the main impurities in the citral were also identified . The synthesis mechanism of citral from dehydrolinalool was discussed.