New Process For Preparation Of Glyphosate And Its Ammonium

N-phosphonomethyl glycine(PMG or glyphosate), which derives from the amino acid, is a kind of the important herbicide. Because of its high effective, low toxicity and little harmful effects on the environment, Glyphosate has been became the most popular herbicide. It is also well known that glyphosate has a low solubility in water at room temperature. Thus, it is more often composed as a water-soluble salt, especially as the ammonium glyphosate to employ. The method, to use recycled liquid, will be helpful in shortening the process, decreasing reagent,saving energy and reducing waste. And this approach is really a valuable one which can upgrade profit and be benefit to environment.A process, utilizing air as the oxidant in the presence of a catalyst consisting essentially of the activated carbon, oxidizes the aqueous solutions of PMIDA (N-phosphonomethyliminodiacetic acid) to obtain glyphosate. The oxidative decarboxylation reaction has many advantages such as moderate condition, good selectivity, high yield, etc., According to a great amount of both domestic and foreign literatures, the oxidative decarboxylation of PMIDA has some characteristics. Several factors can be easily determined to test how they will affect on the reaction. A series of mono-factor's experiments are investigated to optimize the reaction. Based on these experimental results, the optimum conditions are found: that concentrate of PMIDA is 26%, the mass ratio of activated carbon to PMIDA is 0.34:1, the temperature is 65℃, the pressure is 0.90Mpa, the gas flow is 140ml/min, the stir speed is 900rpm. Under this reaction condition, the overall yield of PMG is 92%, which increased 2% than industrial production.By comparing glyphosate and its ammonium salt of the respective solubility with temperature variations, a novel preparation process is proposed that the solid glyphosate ammonium salt can be obtained by recycled liquid. Then based on the aforementioned optimum conditions, the overall yield of this method can achieve 86%, the yield of solid ammonium salt is 81%, and the content can reach more than 95%. Through the analysis computation the new process to converte glyphosate to its solid ammonium salt has obtained a high yield of 97.76%. The results are in general agreement with the literature values. But the novel process can shorten the route, decrease reagent consumption, lessen energy consumption, cut down waste emissions.