The Study Of Chloroacetic Acid Of Glyphosate With The Method Of One-Pot Synthesis

N-phosphonomethylglycine(PMG) is a kind of broad-spectrum herbicides with high efficiency, low toxicity,good bioactivity and other characteristics, which destroys the ruderal after in bud and derives from the amino acid. Because of it's superior performance,recently it has been the largest amount of the herbicides in the world. There are mainly two methods to synthetize glyphosate, one way is using glycine as the starting material,the other is using iminodiacetic acid. And the first way is wirdly used in China. First,the synthesis of glyphosate through glycine-dimethyl phosphate was studied in the paper, the optimum conditions were obtained. And a new technology of syntheticing glyphosate was studied based on the best conditions, which used chloroacetic acid, paraformaldehyde and dimethyl phosphite as the main materials, high-purity glyphosate was directly synthetized after synthesis, condensation and hydrolysis through one-pot method. This process has simplified the synthesis process of Preparation of glycine by chloroactic acid and the preparation of glyphosate by glycine, the integration of the two production chain has been achieved, the production costs has recused.The paper mainly focused on four parts. First part:The glycine was synthesized using chloroacetic acid as raw material; The second part: Glyphosate was prepared using glycine and O, O-dimethylphosphite as primary materials in the experiment;The third part:The effect of triethylamine hydrochloride on the total yield of glyphosate and the solution to the problem were studied; The forth part:Glyphosate was synthesized by one-pot method with chloroacetic acid as main material. Some factors were experimentally analyzed, such as the ratio of the reactants, adding order, reaction temperature, reaction time and so on. The optimum process conditionswere shown as follows:(1) First, chloroacetic acid reacted with chloroactic acid to produce an intermediate;Second, paraformaldehyde reacted with anhydrous methanol and ammonia,the flow rate of which is 302 ml per minute, to produce carbinolamine.The reaction time was about one hour and the reaction temperature was 20 degrees. The molar ratio of reactants:chloroacetic acid: triethylamine:paraformaldehyde:anhydrous methanol= 1:1:1.25:3(2) After the above two resultants were mixed about three and a half hours under 60 degrees, glycine would be precipitated in the form of crystals.(3) 0.125 mole of paraformaldehyde,0.3 mole of anhydrous methanol and 0.085 mole of triethylamine were added into the system. The reaction temperature was 40 degrees,and the reaction time was about one hour and a half.(4) After esterification, triethylamine hydrochloride would be precipitated in the form of crystals. The impact of triethylamine hydrochloride on the total yield of PMG was eliminated by freezing and washing by anhydrous methanol. (5) In the hydrolysis process, the molar ratio of chloroacetate and the amount of hydrochloric acid was three to one. Atmospheric distillation time about three hours and a half, Vacuum distillation time was about one hour. The hydrolysis temperature was in the range of 115 to 120 degrees.(6) After adding a little of distilled water to the crystal liquid, adjust the pH value of the crystal liquid about 1.5 by using 30% NaOH solution, which could make the minimum solubility of glyphosate in the mother liquor, the whole reaction ended,and the total yield of PMG could be increased to 55.5%.