Preparation of chlorinated phenoxyalkanoic acids

US4515985A · kind A · utility

Assignee

• BASF SE

Inventors

• Gerd Husslein · Bad Dürkheim, DE
• Gerhard Hamprecht · Weinheim, DE
• Karl-Heinz Koenig
• Walter Boehm · Washington, US
• Manfred Gaeng · Frankenthal (Pfalz), DE

Key dates

• Filing date: Dec 16, 1981
• Grant date: May 7, 1985
• Expiry date: Dec 16, 2001

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C51/367
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

A process for the preparation of 2,4-dichloro- or 2-methyl-4-chlorophenoxyacetic acid or .alpha.-2,4-dichloro- or .alpha.-2-methyl-4-chlorophenoxypropionic acid by reacting phenoxyacetic or 2-methylphenoxyacetic acid or .alpha.-phenoxypropionic or .alpha.-2-methylphenoxypropionic acid with chlorine in water, wherein phenoxyacetic acid or phenoxypropionic acid is precipitated from an aqueous solution thereof, chlorine gas is passed into the resulting suspension of phenoxyacetic or 2-methylphenoxyacetic acid or .alpha.-phenoxypropionic or .alpha.-2-methylphenoxypropionic acid in water at from 30.degree. to 70.degree. C. at a rate not exceeding the rate at which it is consumed in the suspension, until from 100 to 110% of the theoretically required amount of chlorine gas has been taken up by the suspension, and the 2,4-dichloro- or 2-methyl-4-chloro-phenoxyacetic acid or .alpha.-2,4-dichloro- or .alpha.-2-methyl-4-chloro-phenoxypropionic acid is isolated from the suspension.