2,5-二(二乙氨基甲基)对苯二酚在过氧化氢氧化苯甲醇制备苯甲酸中的应用研究

The application of 2,5-bis(diethylaminoethyl)-hydroquinone in oxidation of benzyl alcohol to benzoic acid with H_2O_2 as an oxidant under organic solvent-free conditions

以30%过氧化氢作为氧化剂,对苯二酚与甲醛、二乙胺的Mannich反应产物2,5-二(二乙氨基甲基)对苯二酚与钨酸钠为催化剂,研究了苯甲醇氧化制备苯甲酸的反应,2,5-二(二乙氨基甲基)对苯二酚的辅助催化性能优于对苯二酚。最佳反应条件为:40.5mmol苯甲醇,n(钨酸钠)∶n(2,5-二(二乙氨基甲基)对苯二酚)∶n(苯甲醇)∶n(30%过氧化氢)=0.405∶0.489∶40.5∶273,3mL0.1mol/L硫酸,于95℃反应8h,在无有机溶剂的条件下苯甲醇可以被氧化为苯甲酸,一次结晶率为76.9%,催化体系的重复使用性能不太理想。

2,5-Bis（ diethylaminoethyl）-hydroquinone was synthesized and used as an co-catalyst during the oxidation of benzyl alcohol to benzoic acid in the presence of 30 % aqueous hydrogen peroxide as an oxidant under organic solvent-free and halides-free conditions. The reaction was catalyzed by a coordination compound system including the peroxotungstate formed in situ from sodium tungstate dehydrate and 2,5-his（ diethylaminoethyl）-hydroquinone under organic solvent-free and halide-free conditions. The influence of the reaction conditions including the temperature, reaction time, amounts of catalyst, ligand, sulphuric acid and 30% aqueous hydrogen peroxide was studied .The results showed that when benzyl alcohol dosage was 40.5 mmol, the reaction was conducted at an optimum molar ratio of sodium tungstate dehydrate： 2,5-his （ diethylaminoethyl）-hydroquinone ： benzyl alcohol ： 30% H2O2 equating to 0.405：0.489：40.5：273 ,in the presence of 3 mL of 0.1 mol/L aqueous sulphuric acid at a reaction temperature of 95 ℃ and a reaction time of 8 h, resulting in a primary crystallized benzoic acid yield of 76.9%. The recycling of the catalyst system was studied also.