Method of preparing 1,2-dimethyl-3,5-diarylpyrazolium methylsulfates
AssigneeBASF SE
InventorsHans Rupert Merkle, Erich Fretschner
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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 a) methanol and SO.sub.3, b) methanol and sulfuric acid or optionally, c) methanol and methylsulfuric acid elevated temperatures.
Claims4
A process for the preparation of 1,2-dimethyl-3,5-diarylpyrazolium methylsulfates of the formula I ##STR7## 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, which comprises reacting 1-methyl-3,5-diarylpyrazoles of the formula II ##STR8## where R.sup.1 and R.sup.2 have the above-mentioned meanings with a) methanol and SO.sub.3,
- b) methanol and sulfuric acid or
- c) methanol and methylsulfuric acid
- at elevated temperatures.
Dependencies are inferred from the claim text.