Process for the preparation of pyrazole

US4423225A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Reinhard Lantzsch · Leverkusen, DE
• Klaus Ditgens · Wuppertal, DE
• Ulrich Heinemann · Leichlingen, DE
• Rudolf Thomas · Haan, DE
• Erhard Weber · Bocholt, DE

Key dates

• Filing date: Sep 8, 1981
• Grant date: Dec 27, 1983
• Expiry date: Sep 8, 2001

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D231/12
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Process for the preparation of pyrazole by heating a pyrazoline derivative of the general formula ##STR1## in which R represents an optionally substituted phenyl radical, or an alkyl or halogenoalkyl radical, without the addition of an acid or base, at a temperature between 100.degree. and 200.degree. C. under a pressure between 1 mbar and 10 bars, optionally in the presence of a diluent.