Method of preparing 1,2-dimethyl-3,5-diarylpyrazolium methylsulfates

US5847154A · kind A · utility

Assignee

• BASF SE

Inventors

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

Key dates

• Filing date: Jan 13, 1998
• Grant date: Dec 8, 1998
• Expiry date: Jan 13, 2018

Classification

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

Abstract

A process for the preparation of 1,2-dimethyl-3,5-diaryl-pyrazolium methylsulfates of the formula I ##STR1## where R.sup.1 and R.sup.2 independently of one another are hydrogen, C.sub.1 -C.sub.4 -alkyl, C.sub.3 -C.sub.8 -cycloalkyl, C.sub.1 -C.sub.4 -alkoxy, halogen, nitro, C.sub.1 -C.sub.4 -haloalkyl or aryl all of which are inert under the reaction conditions, in which 1-methyl-3,5-diarylpyrazoles of the formula II ##STR2## where R.sup.1 and R.sup.2 have the abovementioned meanings are reacted with PA1 a) methanol and SO.sub.3, PA1 b) methanol and sulfuric acid or optionally, PA1 c) methanol and methylsulfuric acid elevated temperatures.