The Study Of Catalytic Oxidation Of Primary Alcohols To Carboxylic Acids Over Solid Catalysts

The oxidation of primary alcohols to the corresponding carboxylic acids is one of the most important transformations in organic chemistry. Carboxylic acids, as synthesis of intermediates for alkyd resin, medicine and dye, and preservatives, widely used in industry. Traditionally, the reactions use a stoichiometric ratio of chromate, potassium permanganate and etc. as oxidizing agent; these oxidants are not only expensive, but also generate a large number of hazardous waste.In recent years, from the view of green chemistry, the application of H2O2or O2as oxidant has received great concern. It overcomes shortcomings of the traditional toxic inorganic oxidant. In addition, H2O2/O2provides a large number of active oxygen and water as the only by-product.In this paper, two catalyst systems were developed for the oxidation of alcohols to carboxylic acid using O2/H2O2as oxidant.Sodium tungstate combined sulfonated carbon as catalyst can effectively catalyze the oxidation of benzyl alcohol to the corresponding acid with30wt%H2O2as oxidant. In this paper, the infulence of carbon precursor, carbonization methods, reaction temperature, reaction time, and the amount of sulfonated carbon and other factors on the oxidation of benzyl alcohol were systemically investigated. It was showed that sulfonated fast pyrolysis of sawdust carbon (RC-SO3H) with sodium tungstate exhibited the best catalytic performance. About100%conversion with86%isolated yield of benzoic acid was gaved at100℃and10h.Au/NaY can effectively catalyze the oxidation of alcohols to the corresponding acid with molecular oxygen as oxidant. The preparation conditions for catalyst, including pH and temperature of chloroauric acid solution, deposit time and temperature, calcination temperature and the loading amount of Au, on the catalytic properties of Au/NaY were studyed. The proper prameters of the pH and temperature of the solution of HAuCl4, deposit time and calcination temperature were6.0,80℃,16h and300℃, respectively.2%Au/NaY showed the best activity in the oxidation of benzyl alcohol.96.6%conversion with94.4%isolated yield of benzoic acid was obtained at80℃for8h in presence of1.5eq NaOH using1.0MPa O2as oxidant. Au/NaY could be reused for three times, and its catalytic activity almost unchanged.