Process for preparing pyrazoles

US6022979A · kind A · utility

Assignee

• BASF SE

Inventors

• Thomas Barth · Ludwigshafen, DE
• Norbert Rieber · Mannheim, DE
• Klaus Erhardt

Key dates

• Filing date: Jul 13, 1999
• Grant date: Feb 8, 2000
• Expiry date: Jul 13, 2019

Classification

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

Abstract

A process for preparing pyrazoles of the formula I ##STR1## in which R.sup.1,R.sup.2,R.sup.3 independently of one another are C.sub.1 - to C.sub.20 -alkyl, C.sub.3 - to C.sub.8 -cycloalkyl, or C.sub.7 - to C.sub.20 -aralkyl or aryl, unsubstituted or substituted by C.sub.1 - to C.sub.4 -alkyl, halogen and/or nitro, PA1 R.sup.1,R.sup.3 are additionally independently of one another hydrogen, PA1 by reacting a carbonyl compound of the formula R.sup.1 --CH.sub.2 --CO--R.sup.2, in which R.sup.1 and R.sup.2 are as defined above in the presence of a strong base with PA2 a) formic esters of the formula H--COOR.sup.4, in which R.sup.4 is C.sub.1 - to C.sub.8 -alkyl at from (-20) to 70.degree. C. and a pressure of from 1 to 50 bar or PA2 b) carbon monoxide at from 0 to 100.degree. C. and a pressure of from 1.5 to 150 bar and reacting the resulting intermediate, the hydrazines of the formula R.sup.3 --NH--NH.sub.2, in which R.sup.3 is as defined above, and an inorganic or organic acid at from 0 to 90.degree. C. and a pressure of from 1 to 10 bar, which comprises filtering off or centrifuging off the intermediate, is described.