精馏分水—锅法合成富马酸二甲酯

以顺酐为原料，磷钨酸为酯化催化剂，一种含溴的氧化剂为异构化催化剂，通过精馏分水，一锅法合成富马酸二甲酯。考察了酯化时间、酯化催化剂用量、酐醇摩尔比、异构化催化剂用量、异构化温度、异构化时间等因素对反应产率的影响，并得到了最佳工艺条件，即顺n(酐)∶n(甲醇)=1∶8，磷钨酸的用量为顺酐用量的6％，酯化回流4h，蒸出过量甲醇，然后加入顺酐用量1.6％的异构化催化剂，在95～105℃温度下反应30min，产率超过77%。精馏分水法较好地解决了甲酯化反应去水的问题；所采用的酯化催化剂和异构化催化剂对设备腐蚀较小,产品后处理简单，无三废。并且探讨了异构化机理。

One-Pot Synthesis of Dimethyl Fumarate With Rectification to Remove Water

Dimethyl fumarate was prepared from maleic anhydride and methanol with phospho-tungstic acid as the esterification catalyst and an oxidant of bromide as the isomerization catalyst by rectification to remove produced water. The influences of esterification time, the amount of esterification catalyst, the amount of isomerization catalyst, isomerization time and temperature have been investigated. The optimized reaction conditions were obtained as the follows: the mole ratio of maleic anhydride to methanol is 1∶8; the amount of phospho-tungstic acid is 6％(W/W)of the maleic anhydride, and esterification time is 4 h. Then superfluous methanol is removed by distillation. At 95～105 ℃, the isomerization catalyst is added. Its amount is 1.6％(W/W) of the maleic anhydride, and the reaction time is 30 min. The overall yield is over 77%. The rectification is an effective method of removing water for the methanol esterification. The esterification catalyst and the isomerization catalyst all have less corrosive effects to the equipment. The purification of the product is simple. No pollution happens. The mechanism of isomerization has been discussed as well.