Controlled Oxidation Of The Synthetic Chlorobenzaldehyde

p -chlorobenzaldehyde is an important intermediate in the organic synthesis. In recent years, with the development of green chemistry, great attention has been paid on the selective oxidation of p -chlorotoluene to prepare p -chlorobenzaldehyde, using O₂ as clean and cheap oxidant. In the present work, we aimed to study the selective oxidation catalyzed by the Amoco MC catalyst system. Different AmocoMC catalysts were selected and the optimum catalyst system was obtained: Co(OAc)₂- MnSO₄ KBr as catalyst and acetic acid as reaction medium.The effects of different variables on the catalyst system were studied and the optimum reaction conditions were as follows: the amount of the composite catalyst Co/Mn/Br 7%(mass percentage based on),the mass ration of different ingredients 2: 2: 1, reaction temperature 80℃, reaction time 30min, the oxygen pressure 0.3MPa. Under these conditions, 21.95% p -chlorobenzaldehyde was obtained with 41.85% selectivity. To improve the selectivity, the Co/Mn/Br catalyst system with ethanal as an additive was studied and the reaction conditions were also optimized, which were as follows: the amount of ethanal 10%(mole ration base on the substrate), reaction temperature 100°C, reaction time 30min, the oxygen pressure 0.2MPa, the amount of the composite catalyst Co/Mn/Br 7%(mass percentage based on),the mass ration of different ingredients 2: 2: 1. Under these conditions, the yield comes to 24.10% and the selectivity reaches 75.03%.