Partial electrolytic dehalogenation of dichloroacetic and trichloroacetic acid and electrolysis solution

US5362367A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Steffen Dapperheld · Hofheim, DE
• Rudolf Rossmeissl · Mertingen, DE

Key dates

• Filing date: Oct 19, 1993
• Grant date: Nov 8, 1994
• Expiry date: Oct 19, 2013

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C25B3/25
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

Trichloroacetic and dichloroacetic acid are dehalogenated to give monochloroacetic acid by electrolyzing aqueous solutions of these acids in divided electrolysis cells using carbon cathodes; the aqueous electrolytic solutions also contain one or more metal salts having a hydrogen overvoltage of at least 0.4 volt (at a current density of at least 4000 A/m.sup.2) and specific ammonium and/or phosphonium salts. In this process, there is an extremely small evolution of hydrogen at the cathode, even at a very low concentration of the polychlorinated acetic acid, without the high selectivity of conversion of the electrolysis being impaired in continuous operation.