| 摘要 |
A process is disclosed for preparing pyrazole and its derivatives having formula (I), in which the residues R1, R2, R3 and R4 stand for hydrogen, halogen, nitro, carboxyl, sulfonyl or C-organic residues, from alpha,beta-unsaturated carbonyl compounds having formula (II) and from hydrazine or hydrazine derivatives having formula (III). The process is characterised in that an alpha,beta-unsaturated carbonyl compound having formula (II) is at first reacted without additional diluting agents with hydrazine or a hydrazine derivative having formula (III), and the thus obtained reaction mixture is reacted in an additional reaction step with a mixture of sulphuric acid and iodine or a iodineor hydrogen iodide-relasing compound.
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