Purification of indigo

US5536842A · kind A · utility

Assignee

• BASF SE

Inventors

• Udo Bergmann · Darmstadt, DE
• Manfred Gang · Frankenthal (Pfalz), DE
• Reinhold Kohlhaupt · Bischofswerda, DE

Key dates

• Filing date: Oct 21, 1994
• Grant date: Jul 16, 1996
• Expiry date: Oct 21, 2014

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C09B7/02
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

A process for purifying indigo comprises extracting an aqueous leuco indigo alkali metal salt solution with an inert solvent under oxygen-excluding conditions and conventionally regenerating the indigo by oxidation.