Esterification of lactic acid in ethanol distillation

 The 225g80% of lactic acid, 475Ml (380g) 95% ethanol, 100mL of benzene, 2 mL of concentrated sulfuric acid and adding a little water separator distillation apparatus Zinc lactate （ 1000 mL) in. Added to the reaction solution to a boil, steam (ethanol, benzene and water) into the condenser through the distillation column, the water layer was separated and refluxed to the distillation column, column top temperature stabilized at 64.9 ℃. When the aqueous layer was 240g (containing ethanol 119g, water, 99g, benzene, 22g), the basic water separation, the column top temperature was raised to 68 ℃, ferrous lactate ends. After cooling, the reaction solution 6g of anhydrous sodium acetate and sulfuric acid by distillation under reduced pressure. First total reflux 1h, and then under vacuum in 2.45Kpa control reflux ratio of not less than 5, a head temperature of 58 ℃, distillation clear colorless ethyl lactate 226g, yield 96%. the lactic acid with an excess of alcohol in the esterification catalyst, after refining.