Process for preparation of substituted aminomethylphosphonic acids.

摘要

A process is disclosed for the preparation of N-substituted aminomethylphosphonic acids, particularly methylaminomethylphosphonic acid, in high yield and purity with related low production cost using conventional equipment, which comprises the steps of (a) reacting an N-substituted amide with paraformaldehyde in a low molecular weight carboxylic acid to form the N-methylol derivative, (b) reacting the N-methylolamide with PCl3 in excess low molecular weight carboxylic acid and heating to form the phosphonomethyl derivative, (c) hydrolyzing acid chloride and acid anhydride with water, (d) distilling off the low-molecular weight carboxylic acid, (e) hydrolyzing the N-acyl group with water and strong acid catalyst, (f) adding low molecular weight alcohol to crystalline the N-substituted-aminomethyl- phosphonic acid and (g) filtering, and washing the product.