Methyltri-n-octylammonium Peroxotungstate Ionic Liquid Catalized Hydrogen Peroxide Oxidation of Benzyl Alcohol to Benzoic Acid

An ionic liquid methyltri-n-octylammonium peroxotungstate [(CH3)N(n-C8H17)3]2W2O11 was synthesized via an one-step process using methyl trioctyl ammonium chloride [(CH3)N(n-C8H17)3]Cl and sodium tungstate as precursors.The oxidation of benzyl alcohol to benzoic acid by H2O2 was studied using the obtained ionic liquid as catalyst under solvent-free condition.The optimized reaction conditions are: the amount of benzyl alcohol substrate is 5.0 mmol,the molar fraction of ionic liquid catalyst to the substrate is 0.4%,the amount of hydrogen peroxide is 20.0 mmol and the reaction temperature is 70 ℃.Under these optimized conditions,the conversion of benzyl alcohol can reach 99% while the selectivity is over 98%.The advantages of this reaction include solvent free,mild reaction conditions,high yield and selectivity of target product.