Preparation of 3-chlorophthalic anhydride

US5683553A · kind A · utility

Assignee

• BASF SE

Inventors

• Karl Baur · Baierbrunn, DE
• Erwin Brunner · Meiningen, DE
• Eckhardt Brandt · Schifferstadt, DE

Key dates

• Filing date: Dec 28, 1995
• Grant date: Nov 4, 1997
• Expiry date: Dec 28, 2015

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C51/573
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

A process for preparing essentially pure 3-chlorophthalic anhydride from a mixture in which 3-chlorophthalic anhydride is present in addition to 4,5-dichlorophthalic anhydride, which involves first distilling off a mixture of 3-chlorophthalic anhydride and 4,5-dichlorophthalic anhydride, so that the obtained bottoms is essentially free of 4,5-dichlorophthalic anhydride, and then by distillation of the obtained bottoms, recovering 3-chlorophthalic anhydride in a second distillation step. The starting mixture is preferably prepared without solvent in a melt by incomplete chlorination of phthalic anhydride using FeCl.sub.3 as a catalyst.