Process Opimization For Synthesis Of N-(Phosphonomethyl) Iminodiacetic Acid

Glyphosate is a kind of low toxic and high efficient herbicide with systemicity, which was first developed by John-E-Franz of Monsanto chemical company in 1971. Currently, as the the most widely used and the largest current consumption herbicide in the world, glyphosate has been the most popular in the 1980s. Especially with the development of the acreage of genetically modified crops, the market demand of glyphosate has been more and more strongly promoted. Due to the increasingly intense competition in the market at home and abroad, we have to put more forward on the quality of product and the cost of production. Therefore, to explore a low cost production process of glyphosate production process is very important. And the N-phosphonomethyl iminodiacetic acid (PMIDA) is one of the most important intermediate of glyphosate synthesis, thus improving the preparation of the N-phosphonomethyl aminodiacetic acid (PMIDA) is the key glyphosate synthesis.Iminodiacetic acid (IDA) method has become the international mainstream. Because the technology of N-phosphonomethyl iminodiacetic acid (PMIDA) oxide to prepare glyphosate is more mature, the main content of this topic research is to pyepare N-phosphonomethyl aminodiacetic acid (PMIDA), shorten reaction cycle and reduce the cost. Compared the advantages and disadvantages for the several kinds of synthesis method of the iminodiacetic acid (IDA), analyzed the research progress of the route, according to the experimental conditions, we decided to adopt to iminodiacetonitrile (IDAN) as raw material. After alkaline hydrolysis, acidification and condensation process synthesis, we finally get N-phosphonomethyl aminodiacetic acid (PMIDA).First, we studied the alkaline hydrolysis and acidification process for synthesis of iminodiacetic acid, which iminodiacetonitrile (IDAN) has been taken as the raw material. The iminodiacetonitrile (IDAN) suspension can react with sodium hydroxide solution, with alkaline hydrolysis by using temperature progyammed and removing ammonia process at the same time. Then excessive hydrochloric acid is added to acidification, next, the solution is filtered to remove heat byproduct sodium chloride, the rest of the iminodiacetic acid solution to continue the next response, Which can eliminating the cooling, crystallization process. In order to reduce the solubility of sodium chloride, considering the condensation section is still to join the hydrochloric acid, we join the hydrochloric acid for the condensation using hydrochloric acid. In this way,we can not only shortens the reaction period, also simplifies the process. By using single factor experiment to investigate the effects of reaction conditions on the results, we determined the optimum reaction condition:the best ratio of material is sodium hydroxide/hydrochloric acid/iminodiacetonitrile=2.2:3.4:1, sodium hydroxide concentration is 25%, temperature progyammed, kept at 60～65℃ for charging 1 h, kept at 70～75℃ for 0.5 h, kept at 80～85℃ for 0.5 h, kept at 90～95℃ for 0.5 h, kept at more than 100℃ for 2 h to remove ammonia.Second, we studied the iminodiacetic acid, formaldehyde and phosphorous acid in the process of condensation reaction in acidic environment. Add the phosphorous acid to the iminodiacetic acid solution, then heating up to the condensation temperature, following add the formaldehyde to the solution, then insulation for a period of time. After cooling, crystallization, the suction filter washing, drying, we finally get N-phosphonomethyl aminodiacetic acid (PMIDA). In the same way, By using single factor experiment to investigate the effects of reaction conditions on the results, we determined the optimum reaction condition:the best ratio of material is formaldehyde/phosphorous acid/iminodiacetic acid=1.2:1.2:1, the dropping time of formaldehyde is 2h, the reaction temperature is 110℃, and the holding time is 1.2 h. In conclusion, through optimizing the reaction condition, we adopt innovatively hot filtering technique to remove byproduct sodium chloride, which eliminating the iminodiacetic acid crystallization process, thus, we can improve N-phosphonomethyl aminodiacetic acid (PMIDA) synthetic route, shorten the reaction cycle, reduce the production cost. Finally, we can enhance the market competitiveness of N-phosphonomethyl aminodiacetic acid (PMIDA) synthetic, which has a wide prospect of industrialization.