Composition and treating aqueous solutions with N-carboxy alkyl amino alkane polyphosphonic acids and their alkali metal salts

US4308147A · kind A · utility

Assignee

• Benckiser-Knapsack GmbH · DE

Inventors

• Klaus Sommer · Heidelberg, DE
• Hermann Weber

Key dates

• Filing date: Nov 7, 1979
• Grant date: Dec 29, 1981
• Expiry date: Nov 7, 1999

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07F9/3808
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Disclosed are a composition and method for treating aqueous solutions with N-carboxy alkyl amino alkane polyphosphonic acids which have more than two carbon atoms in their carboxy alkyl group, and their alkali metal salts. The acids and salts are prepared in a good yield by reacting alkali metal salts of amino alkane phosphonic acids in which at least one hydrogen atom of the amino group is unsubstituted, in an alkaline medium with an .alpha.,.beta.-unsaturated carboxylic acid at increased temperature. The free acids are preferably recovered from the reaction solution by a treatment with a cation exchange agent. In place of the .alpha.,.beta.-unsaturated carboxylic acids there can also be used their anhydrides, esters, or nitriles. The resulting polyphosphonic acids have a good complexing or sequestering effect on polyvalent metal ions.