假性紫罗兰酮的合成研究

Study of the Synthesis of Pseudoionone

以柠檬醛和乙酰乙酸酯类化合物为原料,以仲胺类有机碱为缩合催化剂,制得中间体2-乙酰基-5,9-二甲基-葵-2,4,8-三烯酸酯类化合物及其烯醇式衍生物;将中间体混合物在稀的碳酸氢钠水溶液中进行水解脱羧反应制得假性紫罗兰酮.本文研究了乙酰乙酸酯和仲胺的种类对反应的影响,通过正交实验,优化反应条件,筛选更优异的合成工艺:以二乙胺为碱性缩合剂,柠檬醛与乙酰乙酸甲酯在20℃温度下缩合反应1.5 h,收率为98.8%,脱羧反应收率98.0%,两步总收率96.8%,产品气相含量97%.工艺具有收率高、操作简便、废水少等特点,具有工业化前景.

2-Aceto-5,9-dimethyl-2,4,8-decatrienoic acid esters and its enol derivatives were synthesized via a condensation with citral and acetoacetic esters promoted by organo-secondary amines,which were then decarboxylated in the dilute sodium bicarbonate solution to afford the target product—pseudoionone.Different acetoacetic esters and secondary amines were employed and the reaction conditions were also optimized.A better technique is a condensation with citral and ethyl acetoacetate catalyzed by ethylenediamine at 20℃for 1.5 h with the yield of 98.8%,and the yield of decarboxylation is 96.8%.So the overall yield is 96.8%with a GC content of 97%.High yield,simple operation,and less waste water were observed in this methodology,which has a scale-up production prospect.