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US 7,002,023 B2Granted
Method for producing 1 substituted 5-chloro-4 methly pyrazoles
AssigneeBASF SE
InventorsHans Rupert Merkle, Erich Fretschner
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Abstract
The present invention relates to a process for preparing 1-substituted 5-chloro-4-methylpyrazoles of the general formula I with the meaning for R stated in claim 1, in which a 4-methylpyrazole of the formula II is reacted with chlorine, the resulting mixture of monochlorinated and dichlorinated product is fractionated by distillation, and subsequently the dichlorinated compound is dehalogenated to compound II and returned to the reaction with chlorine.
Claims11
A process for preparing 1-substituted 5-chloro-4-methylpyrazoles of the formula I
- in which
- R is C1–C8-alkyl or C5–C10-cycloalkyl, each of which optionally has one or more substituents,
- by reacting a 4-methylpyrazole of the formula II
- in which
- R has the abovementioned meanings, with chlorine, resulting in a mixture of compound I and a 1-substituted 3,5-dichloro-4-methylpyrazoIe compound III
- in which
- R has the aforementioned meanings, wherein the compound III is separated from the compound I, the compound III is dehalogenated to give the compound II, and the latter is returned to the reaction of II with chlorine.
4 more elements
Dependencies are inferred from the claim text.