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US 2004/0063995 A1Published application
Method for producing n-phosphonomethyl iminodiacetic acid
AssigneeBASF SE
InventorsMatthias Maase, Michael Drogemuller
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AssigneeBASF SE
InventorsMatthias Maase, Michael Drogemuller
Estimating the term…
The present invention relates to a process for the preparation of N-phosphonomethyliminodiacetic acid by reacting an alkali metal salt of iminodiacetic acid with phosphorus trichloride in aqueous solution with formation of the hydrochloride of iminodiacetic acid, phosphorous acid and of the corresponding alkali metal chloride, followed by reaction with a formaldehyde source and, if desired, recovery of the N-phosphonomethyliminodiacetic acid from the reaction mixture, in which water, which may comprise HCl, is removed from the reaction mixture during and/or after reacting the alkali metal salt of iminodiacetic acid with phosphorus trichloride until the concentration of iminodiacetic acid hydrochloride is at least 40% by weight, based on the weight of the reaction mixture minus the weight of alkali metal chloride. The process makes possible the preparation of N-phosphonomethyliminodiacetic acid in a simple fashion and in high yield.
A process for the preparation of N-phosphonomethyliminodiacetic acid by reacting an alkali metal salt of iminodiacetic acid with phosphorus trichloride in aqueous solution with formation of the hydrochloride of iminodiacetic acid, phosphorous acid and of the corresponding alkali metal chloride, followed by reaction with a formaldehyde source and, if desired, recovery of the N-phosphonomethyliminodiacetic acid from the reaction mixture, in which water, which may comprise HCl, is removed from the reaction mixture during and/or after reacting the alkali metal salt of iminodiacetic acid with phosphorus trichloride until the concentration of iminodiacetic acid hydrochloride is at least 40% by weight, based on the weight of the reaction mixture minus the weight of alkali metal chloride.
A process as claimed in any of the preceding claims, wherein the amount of HCl in the reaction mixture before the reaction with the formaldehyde source is brought to 5 to 20% by weight, based on the amount by weight of water in the reaction mixture.
A process as claimed in any of the preceding claims, wherein approximately 1.0 to 1.2 molar equivalents of phosphorus trichloride are used.
A process as claimed in any of the preceding claims, wherein the formaldehyde source is employed in such an amount that 1.0 to 1.5 molar equivalents of formaldehyde are available.
A process as claimed in any of the preceding claims, wherein, to recover the N-phosphonomethyliminodiacetic acid, the pH of the reaction mixture is brought to not more than 1.3 by adding a base.
Dependencies are inferred from the claim text.