Control of n-(phosphonomethyl)iminodiacetic acid conversion in manufacture of glyphosate

A method for monitoring or detecting conversion of N-(phosphonomethyl)iminodiacetic acid to N-(phosphonomethyl)glycine or an intermediate for N-(phosphonomethyl)glycine during catalytic oxidation of N-(phosphonomethyl)iminodiacetic acid in an aqueous medium within an oxidation reaction zone, the method comprising:

• introducing the aqueous medium containing N-(phosphonomethyl)iminodiacetic acid into said oxidation reaction zone;
• contacting N-(phosphonomethyl)iminodiacetic acid with an oxidizing agent in the aqueous medium within said oxidation reaction zone in the presence of an oxidation catalyst, thereby effecting catalytic oxidation of N-(phosphonomethyl)iminodiacetic acid and producing N-(phosphonomethyl)glycine;
• obtaining a series of Fourier transform infrared (FTIR) analyses of the N-(phosphonomethyl)iminodiacetic acid content of the aqueous medium during the catalytic oxidation, wherein said series of FTIR analyses is obtained under non-zero order reaction conditions;
• identifying a target conversion of N-(phosphonomethyl)iminodiacetic acid to N-(phosphonomethyl)glycine or said intermediate for N-(phosphonomethyl)glycine, and/or a target end point defined by a target residual N-(phosphonomethyl)iminodiacetic acid content;
• and
• from said series of FTIR analyses, projecting a batch reaction time or continuous oxidation residence time within said oxidation reaction zone necessary to achieve said target conversion or said target end point;
• and
• wherein said projecting is made on the basis of a substantially first order reaction and said batch reaction time or continuous oxidation residence time is projected based on straight line extrapolation on a logarithmic plot of remaining N-(phosphonomethyl)iminodiacetic acid concentration versus time.