Process for preparing ethanebis(alkylphosphinic) acids

US6583315B2 · kind B2 · utility

Assignee

• Clariant Corporation · DE

Inventors

• Martin Sicken · Cologne, DE
• Norbert Weferling · Hürth, DE
• Hans-Peter Schmitz · Mönchengladbach, DE

Key dates

• Filing date: Dec 19, 2001
• Grant date: Jun 24, 2003
• Expiry date: Dec 19, 2021

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07F9/305
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The invention relates to a process for preparing ethanebis(alkylphosphinic) acids bya) reacting elemental yellow phosphorus with alkyl halides in the presence of alkali metal hydroxide or of alkaline earth metal hydroxide to give a mixture whose main constituents are the alkali metal salts and/or alkaline earth metal salts of alkylphosphonous, phosphorous, and hypophosphorous acid,b) liberating alkylphosphonous, phosphorous, and hypophosphorous acid by adding mineral acids, and also at the same time precipitating the alkali metal ions and, respectively, alkaline earth metal ions in the form of their salt of the mineral acids, and thenc) esterifying the alkylphosphonous acid from the mixture of the alkylphosphonous, phosphorous, and hypophosphorous acid,d) isolating the ester of alkylphosphonous acid from the mixture and hydrolyzing the same to give alkylphosphonous acid, ande) preparing, from the alkylphosphonous acid, the corresponding ethanebis(alkylphosphinic) acid of the general formula (I) where R1 and R2 may be identical or different and are hydrogen, a carboxy group, a carboxylic acid derivative, an unsubstituted or substituted alkyl group having from 1 to 10 carbon atoms, p…