Patent ID: 6118022
Filing Date: 2000-09-12
Classification: C07F

Abstract:
A process for producing phosphonomethyliminodiacetic acid, comprising:a) reacting an aqueous solution containing a metal salt of iminodiacetic acid with a sufficient amount of a strong mineral acid to convert said salt to iminodiacetic acid and the metal salt of said strong acid;b) adding a phosphorous acid source to the reaction product of step a) to form a solution of iminodiacetic acid phosphite salt;c) separating the precipitated metal salt of said strong mineral acid from said solution of iminodiacetic acid phosphite salt;d) phosphonomethylating said iminodiacetic acid phosphite salt with a phosphorous acid source and a formaldehyde source in the presence of a strong mineral acid to produce phosphonomethyl-iminodiacetic acid and a mother liquor; ande) recovering phosphonomethyliminodiacetic acid from said mother liquor.