Process for preparing N-substituted pyrazoles

US5840913A · kind A · utility

Assignee

• BASF SE

Inventors

• Hans Rupert Merkle · Ludwigshafen, DE
• Erich Fretschner · Neckarsteinach, DE
• Jürgen Schröder · Ludwigshafen, DE

Key dates

• Filing date: Aug 20, 1997
• Grant date: Nov 24, 1998
• Expiry date: Aug 20, 2017

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D249/08
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

A process for the preparation of an N-alkyl- or N-phenylalkyl-substituted pyrazole I by reacting the corresponding N-unsubstituted pyrazole II with an alcohol III of the formula R.sup.1 --OH where R.sup.1 is the same alkyl or phenylalkyl group to be added to the unsubstituted nitrogen group --NH-- of the pyrazole reactant. Both of the reactants, i.e. the pyrazole II and alcohol III compounds, are catalytically reacted in the liquid phase in a molar ratio of from 0.001:1 to 1:1, at temperatures of 50.degree.-400.degree. C. and under a subatmosheric pressure of from 0.8 bar up to a superatmospheric pressure of 250 bar. The catalyst required for this liquid phase reaction is selected as being at least one or more non-heterogeneous acid catalysts, their alkyl esters or their acid anhydrides.