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

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

• introducing an aqueous medium containing N (phosphonomethyl)iminodiacetic acid into an oxidation reaction zone;
• contacting N-(phosphonomethyl)iminodiacetic acid with an oxidizing agent in said aqueous medium within said oxidation reaction zone in the presence of a catalyst for the oxidation, thereby effecting oxidation of N-(phosphonomethyl)iminodiacetic acid and producing N-(phosphonomethyl)glycine or said another intermediate;
• continually or repetitively measuring the exothermic heat generated in said reaction zone;
• monitoring the instantaneous rate of exothermic heat generated in the conversion of N-(phosphonomethyl)iminodiacetic acid to N (phosphonomethyl)glycine or said another intermediate;
• and
• estimating the residual concentration of N (phosphonomethyl)iminodiacetic acid in said aqueous medium within said reaction zone, said estimating comprising comparing said rate of exothermic heat generation with the mass of aqueous medium containing N-(phosphonomethyl)iminodiacetic acid that is charged to the reaction zone or a function thereof.

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

• obtaining a series of Fourier transform infrared (FTIR) analyses of the N-(phosphonomethyl)iminodiacetic acid content of the aqueous reaction medium during the course of the reaction;
• identifying a target conversion of N (phosphonomethyl)iminodiacetic acid to N (phosphonomethyl)glycine or said another 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 the batch reaction time or continuous oxidation residence time within said oxidation reaction zone at which said target conversion or end point may be anticipated to be attained.

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

• introducing an aqueous medium containing N (phosphonomethyl)iminodiacetic acid into an oxidation reaction zone;
• contacting N-(phosphonomethyl)iminodiacetic acid with molecular oxygen in said aqueous medium within said oxidation reaction zone in the presence of a catalyst for the oxidation, thereby effecting oxidation of N-(phosphonomethyl)iminodiacetic acid and producing N-(phosphonomethyl)glycine or said another intermediate;
• measuring the consumption of molecular oxygen in said reaction zone;
• and
• estimating the proportion of N-(phosphonomethyl)iminodiacetic acid that has been converted to N-(phosphonomethyl)glycine or said another intermediate in said reaction zone, said estimating comprising comparing the oxygen consumed in said reaction zone with the mass of N-(phosphonomethyl)iminodiacetic acid charged to the reaction zone and the unit oxygen consumption required for the oxidation of N-(phosphonomethyl)iminodiacetic acid to N (phosphonomethyl)glycine or said other N (phosphonomethyl)glycine intermediate.