4,5-二溴邻苯二甲酸的合成

Studies on the Synthetic Process of 4,5-Dibromophthalic Acid

4,5-二溴邻苯二甲酸是合成羧基取代类酞菁化合物的中间体。该文以邻二甲苯在溶剂二氯甲烷的存在下与溴素发生亲电取代反应生成4,5-二溴邻二甲苯,4,5-二溴邻二甲苯再与高锰酸钾发生氧化反应生成4,5-二溴邻苯二甲酸。该文系统研究了工艺条件对两步反应收率的影响,结果表明,4,5-二溴邻二甲苯反应的最优反应条件是Br2的体积分数为40%,邻二甲苯的体积分数为40%,n(Br2)∶n(I2)∶n(邻二甲苯)=3.0∶0.15∶1.0,在该条件下进行稳定和10倍放大实验,产品收率达到79.0%。4,5-二溴邻苯二甲酸的反应在n(高锰酸钾)∶n(四丁基溴化铵)∶n(4,5-二溴邻二甲苯)=6.0∶0.04∶1.0,反应温度为100℃,反应时间为10 h时条件最优,在该条件下进行稳定和10倍放大实验,产品收率达到85.5%,两步反应收率较文献报道71.0%和77.0%有所提高。

4, 5-Dibromophthalic acid was an intermediate for the synthesis of carboxyl substituted phthalocyanine compounds. In the presence of the solvent methylene chloride, 4,5-dibromo-o-xylene was synthesized from o-xylene and bromide through electrophilic substitution reaction. Then, it went through the oxidation with potassium permanganate to give 4,5-dibromophthalic acid. By studying the process conditions, we got the optimal reaction conditions of 4,5-dibromo-o-xylene as follows： Br2 volume concentration 40%, o-xylene volume concentration 40% , Br2 ： 12 ：o-xylene （3.0：0. 15：1.0, molar ratio）. By amplifying the experimental conditions by 10 times,we got the yield of 79.0%. And the optimal reaction conditions of 4,5-dibromophthalic acid were：potassium permanganate, phase transfer catalyst and 4, 5-dibromo-o-xylene whose molar ratio were 6. 0 ： 0.04 ： 1.0, reaction time 10 h, temperature 100 ℃. By amplifying the experimental conditions by 10 times,we got the yield of 85.5%, which was higher than the reported yields of 71.0% and 77.0%.