Method for preparing N-Phosphonomethyl iminodiacetic acid through hydrolyzing iminodiacetonitrile

Abstract

The invention discloses a method for preparing N-Phosphonomethyl iminodiacetic acid through hydrolyzing iminodiacetonitrile, which comprises the following steps: hydrolyzing and deaminating the iminodiacetonitrile by using lime aqueous solution to obtain solution with the iminodiacetonitrile, acidizing the solution by using hydrochloric acid aqueous solution and sulfuric acid aqueous solution, filtering calcium desulfurization, decoloring filtrate by using active carbon; removing sulfate ions by using barium salt, removing metal ions through an ion-exchange resin column, condensing to obtain solution with iminodiacetic acid salt, reacting with phosphorous acid and formaldehyde under the catalysis of inorganic acid, condensing, crystallizing and filtering reaction solution, respectively collecting filter cakes and filtrate, finally obtaining N-Phosphonomethyl iminodiacetic acid after the filter cakes are dried, and recycling the filtrate. The invention has the advantages of short process flow, high product recovery rate, low production cost, easy comprehensive utilization of byproducts, less three-waste discharge, low environmental pollution as well as favorable economic and environment benefits.

Description

technical field [0001] The invention relates to a preparation method of diglyphosate, in particular to a method for preparing diglyphosate by hydrolysis of iminodiacetonitrile. Background technique [0002] Diglyphosate (N-Phosphonomethyl Iminodiacetic Acid, PMIDA) is an important intermediate of glyphosate, the herbicide with the largest production and sales volume in the world, and has broad market prospects. [0003] The traditional preparation method of diglyphosate is the iminodiacetic acid (IDA) method developed by U.S. Monsanto Company, that is, with hydrocyanic acid or diethanolamine as starting raw material, first prepare high-purity iminodiacetic acid solid, and then combine with phosphorous acid Or phosphorus trichloride, formaldehyde carry out condensation reaction to prepare bisglyphosate. Among them, the preparation of high-purity iminodiacetic acid solid needs to acidify the intermediate iminodiacetic acid disodium salt with sulfuric acid, convert it into imi...

AI Technical Summary

Problems solved by technology

Among them, the preparation of high-purity iminodiacetic acid solid needs to acidify the intermediate iminodiacetic acid disodium salt with sulfuric acid, convert it into iminodiacetic acid, and then prepare it through the processes of concentration, crystallization, separation and drying. There is a process flow Long, low product yield, high production cost, large environmental pollution and other shortcomings

In order to overcome the above shortcomings, researchers have made a series of improvements to the method. Chinese patent CN 1721422A discloses a method for directly preparing diglyphosate from the crude salt of iminodiacetic acid disodium salt, which saves the preparation of high-purity imino The complex process of diacetic acid solids, but the preparation of iminodiacetic acid disodium salt crude salt also needs to go through processes such as concentration, crystallization, separation and drying, and there are still long technological processes, low product yields, high production costs, Environmental pollution and other issues

Chinese patent CN 1916005A discloses a method for directly preparing bisglyphosate from iminodiacetic acid disodium salt aqueous solution obtained by hydrolysis of iminodiacetonitrile, which saves the complicated process of preparing iminodiacetic acid disodium salt solid, making the process The process is shortened, the product yield is increased, and the production cost is reduced, but its by-product sodium chloride contains a large amount of organic impurities, which is difficult to comprehensively utilize, and the amount of saline wastewater is large, which puts a lot of pressure on the environment