Method for preparing 1-alkyl-pyrazol-5-carboxylic acid esters III

US6444828B1 · kind B1 · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Nikolaus Muller · Monheim, DE
• Michael Matzke · Wuppertal, DE

Key dates

• Filing date: Feb 9, 2001
• Grant date: Sep 3, 2002
• Expiry date: Feb 9, 2021

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D231/14
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

1-Alkyl-pyrazole-5-carboxylic esters are obtained with surprisingly low proportions of 1-alkyl-pyrazole-3-carboxylic esters if a 2,4-diketo ester and/or an enolate thereof is reacted with an alkylhydrazine and/or a corresponding alkylhydrazinium salt, if appropriate, in the presence of a solvent and/or of water, in such a manner that during at least about 90% of the reaction free alkylhydrazine is present.