Method for the manufacture of phosphonoalkyl iminodiacetic acid
AssigneeStraitmark Holding AG
InventorsPatrick Notté, David Lemin, Cedric Nicolas Pirard
Life of this patent
Estimating the term…
Abstract
An improved method for the manufacture of phosphonoalkyl iminodiacetic acid M2PO3—X—N—(CH2COOM)2 wherein X is a C1-6 linear or branched alkyl group; and M is selected from hydrogen, alkali, earth-alkali, ammonium and protonated amine is disclosed. The iminodiacetic acid starting material is reacted with a substantially stoichiometric amount of phosphorous acid, in the presence of a large excess of phosphoric acid to thereby yield a reaction medium insoluble reaction product (PAI-DA) which can be separated from the reaction medium. In a particularly preferred approach, the phosphorous acid is prepared in situ starting from liquid P4O6.
Claims13
A method for the manufacture of a phosphonomethyl iminodiacetic acid or a salt thereof having the formula:
- M2PO3—CH2—N—(CH2COOM)2
- Wherein M is selected from hydrogen, alkali, earth-alkali, ammonium and protonated amine;
- comprising the steps of:
- a) reacting iminodiacetic acid with phosphorous acid whereby the phosphorous acid is used in a molar ratio of phosphorous acid:
- iminodiacetic acid of from 0.7:1 to 1.5:1 in the presence of phosphoric acid whereby the molar ratio of phosphoric acid:
- phosphorous acid is of from 9:0.8 to 1:1 and formaldehyde in a molar ratio formaldehyde:
- iminodiacetic acid of from 2:1 to 0.5:1, at a temperature in the range of from 45° C. to 200° C. for a period of from 1 minute to 10 hours, to thereby yield a substantially reaction medium insoluble product;
- b) separating the insoluble reaction product from the reaction medium, and optionally water washing the insoluble reaction product, wherein the mother liquid is, after the separation of the reaction product, recycled into the reaction medium, wherein the term “phosphoric acid” means phosphoric acid prepared in situ starting from P2O5, with the proviso that hydrochloric acid is not present in the reaction medium.
Dependencies are inferred from the claim text.