Patent ID: 6229022
Filing Date: 2001-05-08
Classification: C07D

Abstract:
A process for preparing pyrazole derivatives of the formula I ##STR5##where R.sup.1 and R.sup.2 are, independently of one another, an unsubstituted or substituted C.sub.1 -C.sub.8 -alkyl, C.sub.3 -C.sub.8 -cycloalkyl, C.sub.6 -C.sub.14 -aryl or phenyl-C.sub.1 -C.sub.4 -alkyl group,R.sup.1 can also be hydrogen, andR.sup.3 is hydrogen which comprises reactinga carbonyl compound of the formula II ##STR6##where R.sup.1, R.sup.2 and R.sup.3 have the abovementioned meanings, with hydrazine, hydrazine hydrate or an acid addition salt thereof, in the presence of a 30 to 100% per weight sulfuric acid and from 0.05 to 5 mol %, based on the hydrazine compound, of iodine or of a compound which liberates iodine or hydrogen iodide at from 80 to 200.degree. C. wherein hydrazine compound and carbonyl compound are employed in a molar ratio of from 1:0.8 to 1:1.5.