Add to 3500ml reactor equipped with reflux condenser, stirrer and thermometer300ml (3.55mol) of 50% glyoxal solution, stir and cool, control the temperature to 7±2,Slowly drip 300ml (3.55mol) of 35% hydrogen peroxide solution at the same time within 3 hours,280ml (0.355mol) of 17% ferrous sulfate solution and 120ml (0.75mol) of 15% aqueous ammonia solution, keep at 8±2, react for 3 hours, and let stand overnight, The reaction liquid was filtered to remove the solid by-products, and 350ml of water-carrying toluene was added to the reaction mother liquid.Heat to reflux, remove water, and distill toluene with water-carrying agent to obtain oxidation product.Add 120ml of concentrated sulfuric acid and 700ml of absolute ethanol to the oxidation products.Esterification reaction at 140°C for 3 hours, then distillation under reduced pressure, at 0.02Mpa,The esterification product was collected at 185°C.Add 120ml of 18% sulfuric acid to the esterified product and heat under stirring.The hydrolysis reaction is carried out at 95-98 for 2 hours; the hydrolysis liquid is cooled to room temperature,The precipitated white solid product was filtered, washed 4 times with 120ml of toluene each time, and dried.Obtain 180 g of the target product glyoxylic acid with a purity of 99.5% (HPLC) and a yield of 88%.Melting point is 98.1-98.6.
