2-(4-溴甲基苯基)丙酸合成工艺的优化?

Optimization of synthesis processes of 2-(4-bromomethylphenyl)propionic acid

采用气相循环与反应-萃取技术,优化了2-(4-溴甲基苯基)丙酸(BMPPA)的合成工艺,解决了现有工艺废酸量大、套用困难的问题。在气-液-液反应体系中,水相2-苯基丙酸(PPA)与多聚甲醛(PFA),氢溴酸(HBr)在溴化锌(ZnBr2)催化下反应生成的BMPPA被萃取至有机相,气相与通入的溴化氢气体强制循环,维持体系溴化氢浓度并促进传质。反应结束后,有机相冷却结晶后析出产物,结晶母液和水相套用。优化后工艺条件为ZnBr2:HBr:PFA:PPA的摩尔比为0.5:2.5:1.5:1,反应温度为80℃,时间为8h,萃取剂为正庚烷,纯化后BMPPA收率为86.7%,纯度为98%,水相和有机相套用多次,产品收率仍稳定。相比于现有工艺,该工艺的废酸量排放减少80%。

The synthesis process of 2-(4-bromomethylphenyl) propionic acid (BMPPA) was optimized by gas cycle and reaction-extraction, which solved the problems of large waste acid amounts and re-usage difficulty of traditional processes. In the gas-liquid-liquid reaction system, BMPPA was produced by the reaction of 2-phenylpropionic acid (PPA) with polyformaldehyde (PFA),which was catalyzed by zinc bromide (ZnBr2) in aqueous phase. BMPPA was extracted with organic phase. The gas phase was forced to circulate with the incoming hydrogen bromide gas to maintain hydrogen bromide concentration in the system, which also promoted mass transfer. The product was precipitated by organic phase cooling crystallization after reaction. The bulk liquor and aqueous phase were recycled. The optimized process conditions are as follows: molar ratio of ZnBr2:HBr:PFA:PPA is 0.5:2.5:1.5:1 and reaction at 80 ℃ for 8 hours with extractant of n-heptane. The yield of BMPPA is 86.7% after purification and the purity is 98%. This yield is stable even with water and organic phases are reused. Comparing with traditional processes, the waste acid emission is reduced by 80%.