| 摘要 |
PCT No. PCT/EP94/02708 Sec. 371 Date Feb. 15, 1996 Sec. 102(e) Date Feb. 15, 1996 PCT Filed Aug. 13, 1994 PCT Pub. No. WO95/06036 PCT Pub. Date Mar. 2, 1995A process for preparing pyrazole and its derivatives of the formula I <IMAGE> I where R1, R2, R3 and R4 are each hydrogen, halogen, nitro, carboxyl, sulfonyl or C-organic radicals, from alpha,beta-unsaturated carbonyl compounds of the formula II <IMAGE> II and hydrazine or hydrazine derivatives of the formula III H2N-NHR4 III wherein, initially without additional diluent, an alpha,beta-unsaturated carbonyl compound of the formula II is reacted with hydrazine or a hydrazine derivative of the formula III, and the resulting reaction mixture is reacted in another step with a mixture of sulfuric acid and iodine or a compound which liberates iodine or hydrogen iodide. |
