Continuous preparation of isatoic anhydride

US4328339A · kind A · utility

Assignee

• BASF SE

Inventors

• Gerhard Kilpper · Battenberg, DE
• Johannes Grimmer · Aarhus, DK
• Peter Tonne
• Hans Christoph Horn · Lambsheim, DE
• Eckhard Hetzel · Frankenthal (Pfalz), DE

Key dates

• Filing date: Nov 24, 1980
• Grant date: May 4, 1982
• Expiry date: Nov 24, 2000

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D265/26
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

A process for the continuous preparation of isatoic anhydrides by two-stage reaction of an alkali metal phthalamate and/or alkali metal phthalimidate with an alkali metal hypohalite, the first stage being carried out substantially adiabatically and both stages being carried out at high flow rates, wherein phthalimide and/or phthalamic acid is first dissolved in a certain amount of an alkali metal hydroxide solution, the resulting solution is mixed with a hypohalite and reacted at a particular temperature, acid is then added and the reaction is completed at a particular temperature. The compounds obtainable by the process of the invention are valuable starting materials for the preparation of dyes, crop protection agents and scents.