Preparation of formylphosphonic acid from tertiary aminomethylphosphonic acid N-oxides

A process for preparing N-(phosphonomethyl)glycine, or a salt or an ester thereof, wherein said process comprises decomposing a (phosphonomethyl)amine N-oxide compound in the presence of a decomposition catalyst to produce a formylphosphonic acid derivative and a dephosphonomethylated amine, and reacting said formylphosphonic acid derivative to produce N-(phosphonomethyl)glycine, or a salt or an ester thereof, wherein:

• said formylphosphonic acid derivative has a structure of formula (I):
• said (phosphonomethyl)amine N-oxide compound has a structure of formula (II):
• said dephosphonomethylated amine has a structure of formula (III):
• and wherein:
• R1and R2 are independently selected from the group consisting of H, hydrocarbyl, substituted hydrocarbyl, heterocycle, and a salt-forming cation, and R1 and R2 taken together with the oxygen and phosphorus atoms to which they are attached optionally form a cyclic structure;
• R3 is selected from the group consisting of —CHO and —CH(OR8)(OR9);
• R4 and R5 are independently selected from the group consisting of H, —CH2PO(OR6)(OR7), hydrocarbyl, substituted hydrocarbyl, and heterocycle, and R4 and R5 taken together with the nitrogen atom to which they are attached optionally form a cyclic structure;
• R6 and R7 are independently selected from the group consisting of H, hydrocarbyl, substituted hydrocarbyl, heterocycle, and a salt-forming cation, and R6 and R7 taken together with the oxygen and phosphorus atoms to which they are attached optionally form a cyclic structure;
• and
• R8 and R9 are independently selected from the group consisting of H, hydrocarbyl, substituted hydrocarbyl, and heterocycle, and R8 and R9 taken together with the oxygen and carbon atoms to which they are attached optionally form a cyclic structure.