Preparation of 1-aryl-5-amino-pyrazoles

US4824960A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Bernd Gallenkamp · Wuppertal, DE
• Hermann Arold · Wuppertal, DE

Key dates

• Filing date: Apr 3, 1987
• Grant date: Apr 25, 1989
• Expiry date: Apr 3, 2007

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D401/04
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

A process for the preparation of a 1-aryl-5-amino-pyrazole of the formula ##STR1## in which Ar is in each case optionally substituted phenyl or pyridyl, comprising reacting an arylhydrazine of the formula EQU Ar--NH--NH.sub.2 with acrylonitrile of the formula EQU CH.sub.2 .dbd.CH--CN in a first stage in the presence of a diluent at a temperature between about 20.degree. C. and 100.degree. C. to form the arylhydrazine derivative of the formula EQU Ar--NH--NH--CH.sub.2 --CH.sub.2 --CN, and in a second stage contacting such derivative with an oxidizing agent in the presence of a base at a temperature between about 0.degree. C. and 60.degree. C., thereby to effect oxidation and cyclization. The products are known intermediates for herbicides and insecticides.