2,3-difluoro-6-nitrobenzonitrile and 2-chloro-5,6-difluorobenzonitrile-(2,3-difluoro-6-chlorobenzonitrile), process for their preparation and their use for the preparation of 2,3,6-trifluorobenzoic acid

US5478963A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Ralf Pfirmann · Griesheim, DE
• Theodor Papenfuhs · Frankfurt, DE

Key dates

• Filing date: Jan 21, 1994
• Grant date: Dec 26, 1995
• Expiry date: Jan 21, 2014

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C255/50
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The present invention describes the novel intermediates 2,3-difluoro-6-nitrobenzonitrile and 2-chloro-5,6-difluorobenzonitrile, a process for their preparation and their advantageous use for the preparation of 2,3,6-trifluorobenzoic acid, which in turn is a valuable intermediate for the preparation of insecticides and antibacterial agents. The intermediates according to the invention are prepared from 2,3,4-trifluoronitrobenzene by fluorine/cyanide exchange and subsequent denitrating chlorination. 2,3,6-Trifluorobenzoic acid can be prepared from the novel intermediates, in a manner known per se in the literature, by simple chlorine/fluorine exchange and subsequent hydrolysis in a process which overall is industrially advantageous and economically favorable.