合成4(2)-溴代甲苯的新工艺研究

研究了以水为溶剂,以甲苯和Br2为原料,在合成4-溴甲苯和2-溴甲苯的同时也回收了HBr的新工艺。通过实验确定并优化了反应条件,其最佳工艺条件为:反应物的摩尔比为n(甲苯)∶n(溴)=1∶1;反应温度为20～25℃;溴代反应时间为2.5h;4-溴甲苯的收率可达66.4%,邻溴甲苯的收率可达24.7%;氢溴酸的含量为44.7%～45.1%,收率达80%以上。与重氮盐法相比,本工艺方法的特点是:原料价格低廉,一次反应可得到3种产品,原子利用率几乎达到100%,一次加入的水、H2SO4和Fe可以反复循环使用,整个工艺过程基本实现了零排放,从而大大降低了原料成本,极大地提高了经济效益;对环境无污染,符合节能减排的要求,属于环境友好的绿色化学工艺;工艺操作方便,设备简单,适合于规模化生产。

A new synthetic technics of 4(2)-bromotoluene

Using water as solvent,4-Bromotoluene and 2-bromotoluene were synthesized which were prepared with bromum and toluenel.Hydrobromic acid was also recovered.The optimum reaction condition is under a 1∶1 molar ratio of n（Toluenel）∶n（Bromum） =1∶1 at 20～25℃ for 2.5 h,under which the yield of 4-Bromotoluene is 66.4%,the yield of 2-Bromotoluene is 24.7%,hydrobromide content is 44%～46%,the yield is 80%.Compared with the diazonium salt,the process method is characterized by low-priced raw materials,and the atomic use factor achieves 100% nearly,and the water,the sulfuric acid and the iron can be recycled repeatedly,the entire technological process realize zero emission basically,thus reduce the cost of material greatly,raised the economic efficiency greatly;it do not pollute the environment,which belongs to the environment friendly green chemical technology;The craft is easy,the equipment is simple,suits in the formalization production.