2-溴苯酚合成工艺的优化

Synthesis Process Optimization of 2-Bromophenol

以2-溴-4-叔丁基苯酚、甲苯为原料,经叔丁基转移反应合成重要的有机中间体2-溴苯酚。该文考察了催化剂的种类、用量及反应条件对叔丁基转移反应的影响,结果表明:三氯化铝及其与叔胺盐酸盐的复合盐对叔丁基转移反应具有较好的催化活性。27Al NMR的分析表明:催化活性中心可能是三氯化铝与水解产生的氯化氢反应后形成的氯铝酸。进一步研究表明:氯化氢及溴化氢可提高三氯化铝的催化活性,降低三氯化铝的用量。优化后的工艺条件为:在二氯甲烷溶剂中,4-叔丁基苯酚与Br2在0℃反应,选择性形成2-溴-4-叔丁基苯酚,体系中n(2-溴-4-叔丁基苯酚)∶n(催化剂)∶n(甲苯)=1∶0.3∶6,于30℃"一锅法"反应制备了2-溴苯酚,其中,2-溴-4-叔丁基苯酚反应的转化率可达96.5%、2-溴苯酚的选择性达99.6%。

An important organic intermediate 2-bromophenol could be prepared by the tert-butyl transfer reaction of toluene with 2-bromo-4-tert-butylphenol. The effects of catalyst and reaction condition on ter- butyl transfer reaction of 2-bromo-4-tert-butylphenol were investigated. The resuks show that aluminum trichloride and composite of aluminum trichloride and tertiary amine hydrochloride salt have a better catalytic activity for tert-butyl transfer reaction. The analysis of 27 A1NMR shows that the real catalytic species may be aluminum hydrochloride, which is formed by the reaction of aluminum trichloride and hydrogen chloride from the hydrolysis of aluminum trichloride. Further, the hydrogen chloride and hydrogen bromide can impove the catalytic activity of aluminum trichloride and reduce its dosage. The optimized process condition was obtained. 4-tert-butylphenol reacted with bromine at 0 ℃ in dichloromethane and selectively formed 2-bromo-4-tert-butylphenol, then, 2-bromophenol was prepared through ＂ one pot reaction＂ by adding aluminum trichloride and toluene in mole fraction of n （2-bromo-4-tert-butylphenol） ：n （catalyst） ： n （ toluene ） = 1：0.3：6. The conversion of 2-bromo-4-tert- butylphenol reached 96. 5% and selectivity of 2-bromophenol reached 99.6% ,respectively.