Henkel & Cie G.m.b.h.

Norbert Schindler

Karl-Heinz Worms

Walter Ploger

Process for the preparation of 1-aminoalkane-1,1-diphosphonic acids of the formula ##STR1## in which R.sub.1 represents a member selected from the group consisting of alkyl with 1 to 20 carbon atoms, phenyl, phenylalkyl with 7 to 12 carbon atoms, alkylphenyl with 7 to 12 carbon atoms, and in which R.sub.2 represents a member selected from the group consisting of hydrogen and alkyl with 1 to 4 carbon atoms, consisting essentially of reacting adducts of a hydrogen halide selected from the group consisting of HCl and HBr to a corresponding carboxylic acid amide of the formula

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Monheim-Baumberg, Germany

Norbert Schindler