【摘要】 以钒基化合物为催化剂,在TEMPO(2,2,6,6-四甲基哌啶-1-氧自由基)存在下,能形成快速催化分子氧氧化苯制苯酚的催化体系.在反应过程中,由类似芬顿试剂反应过程生成的羟基自由基亲核进攻苯环,形成羟基环己二烯自由基;该羟基氢可在TEMPO存在的催化体系中消除,同时苯环氢可立即转移至氧原子而生成苯酚.在以[(CH3)4N]4-PMo11VO40为催化剂的体系中,反应1h苯酚收率可从不加TEMPO时的1.2%提高到8.4%;而以V-AlPO5为催化剂时,苯酚收率可从不加TEMPO时的5.0%提高到9.5%,且选择性均较高.更多还原

【Abstract】 Rapid benzene hydroxylation was achieved using a reaction system that consisted of a vanadium-based catalyst, ascorbic acid, and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) with molecular oxygen as the oxidant. The hydroxyl radicals that form by a Fenton-type process attack the benzene ring to produce a hydroxycyclohexadienyl radical. The hydroxyl hydrogen is then abstracted quickly in the presence of TEMPO and phenol forms by the transfer of a hydrogen atom from the benzene ring to oxygen. Over the [(CH3)4N]4-PMo11VO40 catalyst the phenol yield reached 8.3% with a selectivity of 95% in 1 h while trace amounts of phenol were obtained in the normal system without TEMPO.更多还原