Research on the Synthesis of Benzoic Acid by Catalytic Oxidation of Benzyl Chloride in the Presence of Phase Transfer Catalyst

Benzoic acid was synthesized from benzyl alcohol and potassium permanganate by three different phase transfer catalysts(diethylene glycol dimethyl ether,tetrabutylammonium bromide,cetyl trimethyl ammonium bromide,i.e.CTAB).The effects of amount of potassium permanganate,the variations in kinds and concentrations of catalysts on benzoic acid yield were investigated.The results showed that phase transfer catalysts had good catalytic activity for the synthesis of benzoic acid from benzyl alcohol in water,and CTAB was the best option.The optimum reaction condition was benzyl alcohol/ potassium permanganate(molar ratio) =1:2.5.The yield of benzoic acid could reach 77.4%under the followed optimum reaction condition;2.6 mL benzyl alcohol,5.53 g potassium permanganate,80 mL water,0.12 g CTAB as phase transfer catalyst,reaction temperature 90℃,reaction time 1 h and alkaline condition.The yield was increased by 30%compared with that obtained under the same optimum condition without any catalysts.