Oxidation of 2,2＇-Dihydroxy-3,3＇-di-tert-buty-5,5＇-dimethoxyl-biphenyl to 3,3＇-Di-tert-butylbiphenyl-2,5,2＇,5＇-diquinone with Copper（Ⅱ）Chloride as Catalyst：Synthesis,Structure and Spectral Properties of Diquinone

摘要

Use of free air as oxidant and copper（II）chloride as catalyst,3,3＇-di-tert-butylbi-phenyl-2,5,2＇,5＇-diquinone（BBDQ）was prepared via catalytic oxidation of 2,2＇-dihydroxy-3,3＇-di-tert-butyl-5,5＇-dimethoxy-biphenyl（di-BHA）.The yield of reaction attained 95% and the selectivity for BBDQ was 100%.The single-crystal X-ray diffraction analysis reveals that the dihedral angle between two rings（benzene rings for di-BHA and quinone rings for BBDQ）changes from 89.8 to 45.3o,indicating the steric hindrance effects of methyl disappear in the oxidation process.The crystal structures of di-BHA and BBDQ are further confirmed by their spectral characterizations.The probable mechanism for this oxidation process is also discussed.