Process for the isolation of pyrocatechol and hydroquinone

US4308112A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Christoph Jupe · Cologne, DE
• Jurgen Baumert · Cologne, DE
• Gunter Schummer · Pulheim, DE

Key dates

• Filing date: Jul 2, 1980
• Grant date: Dec 29, 1981
• Expiry date: Jul 2, 2000

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C37/685
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

A process is described for the isolation of pyrocatechol and hydroquinone from mixtures containing the same, and phenol and higher boiling accompanying substances. The mixture can be one obtained by reacting phenol with a peroxidic hydroxylating agent and removing some of the phenol and the substances which have a lower boiling point than phenol. The mixture is subjected to a first rectification in which phenol and substances which have a boiling point between phenol and pyrocatechol are obtained overhead to leave behind a bottom product containing pyrocatechol and hydroquinone. The bottom product is subjected to a second rectification in which the pyrocatechol is obtained overhead to leave behind a bottom product containing hydroquinone and higher boiling accompanying substances. This bottom product is fed to a concentrating unit in which hydroquinone is evaporated overhead to leave behind high boiling accompanying substances as residue.