Production of aminoalkylene phosphonic acids and their salts

摘要

The invention comprises crystalline anhydrous amino tri-(methylene phosphonic acid) and the preparation of aminoalkylene phosphonic acids of the general formula wherein R3 and R4 may be the same or different and represent either hydrogen or organic radicals and R1 and R2 may be the same or different and represent (i) hydrogen, (ii) an alkylene phosphonic acid radical of the structure shown within the brackets of the above formula, or (iii) an organic radical, or R1 represents hydrogen and R2 represents a hydroxyl or amino group, and salts thereof comprising reacting together in any order (a) ammonia, a primary or secondary amine, hydroxylamine or hydrazine or a salt of any of these, (b) an aldehyde or ketone and (c) orthophosphorous acid or a salt thereof. The reaction is preferably effected at 85 DEG to 200 DEG C. at a pH below 4 in the presence of 5 to 90% (by weight) of water and at least a catalytic amount of a halide. In modified processes of the invention a compound of any one of the reactants (a), (b) and (c) is reacted with the reaction product of compounds taken from each of the other two classes of reactant. The organic radicals represented by R1, R2, R3 and R4 may be saturated or unsaturated, substituted or unsubstituted, aliphatic, alicyclic, aromatic or heterocyclic, R1 and R2 may contain an alkylene phosphonic acid substituent radical, and the reactants (a) and (b) may contain one or more amino and carbonyl groups, respectively.