对溴甲苯的合成工艺

A Study on the Synthesis of 4-Bromotoluene

以甲苯、液溴为原料,在催化剂存在下直接溴化可制得溴代甲苯。考察了不同温度、反应时间、催化剂组成和溶剂比对反应的影响,得到最佳反应条件:以5A分子筛和I2作为催化剂,甲苯和二氯甲烷溶剂体积比为2∶1,10℃下反应6h,甲苯转化率为77.8%,对溴甲苯收率达到75.2%,对位异构体选择性可达96.6%。本实验确定的对溴甲苯合成的工艺路线原料来源广泛,价格低廉,反应工艺条件温和,3废少,工业化前景广阔。

The bromotoluene was prepared by toluene and liquid bromine as raw materials over catalysts. The effects of different temperature,time,catalysts and solvent ratio were investigated.The best reaction conditions were selected：using 5A molecular sieve and I2as the catalyst,the volume ratio of toluene and methylene chloride was 2∶1,reacted for 6hat 10℃,the conversion of toluene reached 77.8%,the yield of 4-bromotoluene reached 75.2%,the paraisomer selectivity reached 96.6%.The raw materials of this reaction are cheap and widely used,the conditions of this reaction is mild and it has less three wastes, it has broad prospects for industrialization.