Study On Glycolic Acid Synthesis From The Partial Oxidation Of Glycol

As an important fine chemical intermediate, glycolic acid can be widely used in medicine, daily chemical textile industry and so on. Traditional technologies have many disadvantages, long process, small-scale, serious corrosion of equipment, increase investment in equipment, high production costs, low yield, low security, and environmental pollution, thus limited the widespread used. Used the ethylene glycol as the raw material, the hydrogen peroxide as the oxidant, and used new catalysts. Various factors which influence the yield of glycolic acid were studied and optimized. The computational simulation on thermodynamic of glycolic acid synthesis was studied by using the B3LYP method of density functional theory. The structures were optimized by computational analysis. The changes in reaction enthalpy, Gibbs free energy and equilibrium constant for the primary and side reaction were calculated and analyzed with the basic thermodynamic data obtained from vibration frequency analysis.The computational studies on thermodynamics of glycolic acid synthesis can provide the theoretical guidance to the reaction process condition control.HPLC method for determining the hydroxyacetic acid was studied. Using C18 column, the mobile phase consisted 0.3% H3PO4,the flow rate was 0.8 mL/min and the UV absorbance detection was set at 210 nm, column temperature 30?, and then a 10?L aqueous sample was injected directly into the chromatograph. A linear calibration was obtained from 0.05mg/mL to 4mg/mL of glycolic acid (R=0.9998) with the RSD of 3% for peak area, and the average recovery was 99.8%. The testing results show that the method is precise, simple and cost-effective.Glycolic acid was prepared by means of liquid-phase oxidated reaction with glycol, hydrogen peroxide. So the experiment was carried out on the atmospheric pressure as the pressure has little effect on this experiment. The reaction temperature, mole ratio, water content, reaction time were mainly studied. The purity and chemical structure of the products were identified by HPLC and IR. The result showed that the optimum reaction conditions were as following, the ratio of hydrogen peroxide and glycol was 3:1, the oxidation temperature was 85?, the water content was 60%, the reaction time was 2.5h.Under this optimal conditions, the yield of the product is 88.1%, the conversion of glycol is 95.0%, the selectivity of glycol acid is 93.0%?The structures of the reactants and products of synthesis of Glycolic acid was studied by using the B3LYP method of density functional theory. Then the structures were optimized by computational analysis. The changes in reaction enthalpy, Gibbs free energy and equilibrium constant for the primary and side reaction were calculated and analyzed with the basic thermodynamic data obtained from vibration frequency analysis. The simulation results show that both the primary reaction process is exothermic and irreversible, the enthalpy change is-630KJ/mol, the Gibbs free energy change is -745KJ/mol. The side reaction process is exothermic and irreversible, the enthalpy change is -580KJ/mol, the Gibbs free energy change is -558KJ/mol. The computational studies on thermodynamics of glycolic acid synthesis can provide the theoretical guidance to the reaction process condition control.