钛酸异丙酯催化脱氢芳樟醇合成柠檬醛

Synthesis of citral from dehydrolinalool catalyzed by titanium isopropylate

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。

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.