芳香化合物在碘或碘化铵催化作用下的单溴代反应

研究了芳香化合物在碘或碘化铵催化作用下的单溴代选择性反应, 该反应是经过有机高价碘中间体进行的. 通过该反应, 富电子芳香化合物在碘或碘化铵催化作用下很容易与溴化钾、 间氯过氧苯甲酸、 对甲苯磺酸和少量苯的混合物发生反应, 常温下短时间内得到产率良好并具有区域选择性的单溴代芳香化合物. 考察了反应条件的影响, 提出了可能的反应机理, 为简单快速合成单溴代芳香化合物提供了新方法.

Monobromination of Aromatic Compounds Catalyzed by Iodine or Ammonium Iodide

Brominated aromatic compounds have considerable importance in the bulk and fine chemical industries,and they are also found widespread used as intermediates in organic chemistry,for example,in cross-coupling reactions.The preparation of brominated aromatic compounds with molecular bromine is a well-known reaction in organic chemistry.The method requires transition metal-based catalysts and the side product gene-rated in the course is corrosive and toxic hydrogen bromide.To improve the bromination process,considerable efforts especially in recently have been devoted and several bromination reagents have been successfully used in place of molecular bromine,and now the research in exploring the scope of it is still a much-sought process.We have developed an efficient monobromination of electron-rich aromatic compounds catalyzed by iodine or ammonium iodide.In our method,a catalytic amount of molecular iodine or ammonium iodide reacted with benzene and m-chloroperbenzoic acid in the presence of p-toluenesulfonic acid to form the recyclable hypervalent iodine intermediate,with which the bromination of electron-rich aromatic compounds and potassium bromide was fast in THF at room temperature,providing regioselective monobrominated products in good yields.The method has some advantages such as mild reaction conditions,simple procedure and good yields.