3-溴苯酞合成工艺的研究

Study on the Synthesis of 3-Bromophthalide

对3-溴苯酞的几种合成方法进行了比较。研究了以邻甲基苯甲酸为原料合成3-溴苯酞的工艺,较好的工艺条件是邻甲基苯甲酸和溴素的摩尔比为1:2,反应温度140℃,滴加溴素,7.6 h完成溴化过程,采用二氯乙烷作重结晶溶剂,产品总收率78.64%,含量98.71%。尾气冷凝器二台并联设置,解决尾气管道堵塞的问题。尾气吸收采用二级降膜吸收加一级碱液吸收的设置,回收的溴化氢含量≥35%。采用自制干燥剂保存产品。

Several synthetic methods of 3-bromophthalide were compared. The synthesis of 3- bromophthalide from o-Toluic acid was studied. The preferable process conditions were as follows： the molar ratio of o-Toluic acid and bromine was 1：2, the reaction temperature was 140 ℃, bromine was added dropwise, the bromination process was completed in 7.6 h, dichloroethane was the recrystallization solvent. The product yield was 78.64% and the total content was 98.71%. Two exhaust condenser parallelled to avoid the blockage of exhaust pipe. Secondary falling film absorption and one alkali absorption were used to exhaust absorption. The recycling content of hydrogen bromide ≥35%. Products were saved by homemade desiccant.