Synthesis of Acetylsalicylic Acid Catalyzed by SO_4~(2-)/TiO_2 Solid Superacid

Acetylsalicylic acid was synthesized from salicylic acid and acetic anhydride catalyzed by SO2-4/TiO2 solid superacid.The effects of calcination temperature of catalyst,reaction temperature,reaction time,molar ratio of reactants and catalyst amount as well as stability of catalyst were discussed.The optimum conditions were as follows: calcination temperature of catalyst 500℃,reaction temperature 90℃,reaction time 40 min,n(acetic anhydride)∶n(salicylic acid)=2.0∶1,catalyst amount 1.0 g.Under optimum conditions,the yield of acetylsalicylic acid was 77.8%.SO2-4/TiO2 solid superacid catalyst had simple preparation procedure,good repeatability,high catalytical activity,convenient final treatment and non-pollution of three wastes,in accordance with development tendency of energy saving and environment protection as well as green catalysis.