4-N,N-Dimethylaminopyridine promoted selective oxidation of methyl aromatics with molecular oxygen
Zhan Zhang1, Jin Gao, Feng Wang
1State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China. zhangzhan@dicp.ac.cn
Abstract:
4-N,N-Dimethylaminopyridine (DMAP) as catalyst in combination with benzyl bromide was developed for the selective oxidation of methyl aromatics. DMAP exhibited higher catalytic activity than other pyridine analogues, such as 4-carboxypyridine, 4-cyanopyridine and pyridine. The sp3 hybrid carbon-hydrogen (C-H) bonds of different methyl aromatics were successfully oxygenated with molecular oxygen. The real catalyst is due to the formation of a pyridine onium salt from the bromide and DMAP. The onium salt was well characterized by NMR and the reaction mechanism was discussed.
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