农药中间体顺丁烯二酸二乙酯的催化合成

Synthesis of Diethyl Maleate Catalyzed by Ti(SO4)2/SiO2

[目的]探寻合成顺丁烯二酸二乙酯的高效、环境友好型催化剂,并对顺丁烯二酸二乙酯合成工艺进行优化。[方法]使用Ti(SO4)2/SiO2为催化剂,顺丁烯二酸酐和无水乙醇为原料合成顺丁烯二酸二乙酯。探讨酐醇物质的量之比、催化剂用量、反应时间、带水剂等因素对反应酯化率的影响,并对催化剂的重复使用情况进行考察。[结果]合成顺丁烯二酸二乙酯的最佳反应条件为酐醇物质的量之比为1∶3;催化剂用量为顺丁烯二酸酐量的31%;带水剂环己烷用量为15 mL;加热回流2 h;此时,酯化率可达96.41%;并且催化剂Ti(SO4)2/SiO2重复使用4次后,酯化率仍可达到74.54%,产品经GC-MS分析知顺丁烯二酸二乙酯的纯度达90.10%。[结论]Ti(SO4)2/SiO2是合成顺丁烯二酸二乙酯的高效、环境友好型催化剂;该合成工艺操作简便、反应条件温和、收率高、产品纯度高。

[Aims] The highly active and environment-friendly catalyst for the synthesis of diethyl maleate was investigated, and the synthesis conditions of diethyl maleate were optimized. [Methods] Diethyl maleate was synthesized from maleic anhydride and ethyl alcohol by using Ti（SO4）/SiO2 as catalysts. The influencing factor on estcrification rate was investigated such as the amount of catalyst, molar ratio of alcohol to acid, catalyst dosage, reaction time, type and amount of water-carrying agent and the situation of the catalyst used in repeated experiments. [Results] The optimal reaction conditions on synthesis of diethyl maleate were obtained： the molar ratio of alcohol to acid is 3.0 ： 1.0, the dosage of catalyst is 31% （base on the maleic anhydride）, water-carrying agent is cyclohexane, reaction time is 2 h. In this condition the yield of the esterification could reach 96.41%, the esterification rate still reached 74.54% when the catalyst was used at fourth times. The purity of the product reached 90.10% by GC-MS. [Conclusions] Ti（SO4）/SiO2 is a type of high efficient and environment-friendly catalyst for the synthesis of diethyl maleate, and the synthetic process is simple with mild reaction conditions, high yield and purity.