Patent ID: 7091376

Claim:
A method for producing N-(phosphonomethyl) glycine, a salt or an ester thereof, the method comprising contacting formaldehyde, phosphorous acid and an amine, or a salt thereof, having the formula (III): wherein R 4 and R 5 are independently selected from the group consisting of H, —CH 2 PO(OR 6 )(OR 7 ), hydrocarbyl, substituted hydrocarbyl, and heterocycle; and R 6 and R 7 are independently selected from the group consisting of H, hydrocarbyl, substituted hydrocarbyl, heterocycle, and a salt-forming cation; to produce a phosphonomethylation reaction product mixture containing an aminomethylphosphonic acid derivative, or a salt thereof, having the formula (II): wherein R 1 and R 2 are independently selected from the group consisting of H, hydrocarbyl, substituted hydrocarbyl, heterocycle, and a salt forming cation; and R 4 and R 5 are as defined above; contacting said aminomethylphosphonic acid derivative, or a salt thereof, having the formula (II), water and an oxidizing gas in the presence of a catalyst to form an oxidation reaction product mixture containing formylphosphonic acid, or a salt thereof, and controlling the conditions under which said contacting is conducted so that (a) at least about 75% of the aminomethylphosphonic acid substrate is converted to formylphosphonic acid, or a salt thereof, and (b) the molar ratio of formylphosphonic acid, or salt thereof to formic acid is at least about 2:1 in said reaction product mixture; contacting said formylphosphonic acid with glycine to produce a condensation reaction product mixture containing a condensed intermediate; and reducing said condensed intermediate to produce a reduction product mixture containing N-(phosphonomethyl) glycine, or a salt thereof.