Patent ID: 7884248
Filing Date: 2011-02-08
Classification: C07F

Abstract:
1. A method for the manufacture of amino polyalkylene phosphonic acid in presence of not more than 2000 parts-per-million, expressed in relation to the phosphorous acid component (100%), of hydrohalogenic acid, whereby all the available N—H functions in 50% or more of the amine raw material are converted to the corresponding alkylene phosphonic acids, by reacting: (a): phosphorous acid; (b): an amine selected from the group consisting of ammonia, primary amines and polyamines; and (c): a formaldehyde; in reactant ratios as follows: (a):(b) of from 0.05:1 to 2:1; (c):(b) of from 0.05:1 to 5:1; and (c):(a) of from 5:1 to 0.25:1; wherein (a) and (c) stand for the number of moles to be used and (b) represents the number of moles multiplied by the number of N—H functions in the amine, in the presence of an acid catalyst having a pKa equal to or less than (b):(d) of from 40:1 to 1:5; wherein (d) stands for the number of moles of catalyst multiplied by the number of available protons per mole of catalyst, followed by recovering the amino polyalkylene phosphonic acid formed in a manner known per sé.