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[目的]2,4,6-三甲基苯叉丙二酸二乙酯是合成除草剂肟草酮的关键中间体,前人报道的合成方法收率低,而本文报道了新的合成工艺并研究了催化剂种类、用量、原料摩尔比、反应时间和共沸脱水时间对收率的影响。[结果]以哌啶为催化剂,物料比n(2,4,6-三甲基苯甲醛):n(丙二酸二乙酯)为1:1.5,哌啶用量与2,4,6-三甲基苯甲醛等摩尔,回流4 h后,苯共沸脱水4 h,收率可达到97.7%(以2,4,6-三甲基苯甲醛计);用IR、1H RMR、元素分析表征了其结构。[结论]在最优条件下,以哌啶为催化剂,2,4,6-三甲基苯甲醛与丙二酸二乙酯通过Knoevenagel缩合高收率获得2,4,6-三甲基苯叉丙二酸二乙酯。
[Objective] The synthesis of 2,4,6-trimethylbenzene-2-methylmalonate was the key intermediate for the synthesis of herbicide oxime, the synthetic method reported in the previous article had a low yield. However, a new synthesis process was reported in this paper The effects of catalyst type, dosage, raw material molar ratio, reaction time and azeotropic dehydration time on the yield were also studied. [Result] Using piperidine as catalyst, the molar ratio of n (2,4,6-trimethylbenzaldehyde): n (diethylmalonate) was 1: 1.5. Trimethylbenzaldehyde equimolar, refluxed 4 h, benzene azeotropic dehydration 4 h, the yield can reach 97.7% (2,4,6-trimethylbenzaldehyde dollars); IR, 1H RMR, elemental analysis Characterize its structure. [Conclusion] Under the optimum conditions, 2,4,6-trimethylbenzene was obtained by condensation of 2,4,6-trimethylbenzaldehyde and diethyl malonate through Knoevenagel high yield with piperidine as catalyst Diethyl malonate.