| 摘要 |
FIELD: organic chemistry, chemical technology. ^ SUBSTANCE: invention relates to the improved method for preparing 1-(4'-tolyl)-3-methyl-5-pyrazolone used in manufacturing dyes and pigments. 1-(4'-Tolyl)-3-methyl-5-pyrazolone is prepared by diazotization of p-toluidine and the following reducing p-tolyldiazonium chloride with sulfite-bisulfite mixture prepared from sodium (ammonium) bisulfite and ammonia water at pH = 5.8-7.0 and the mole ratio bisulfite to p-tolyldiazonium = 2.49:1, hydrolysis of p-tolyl sulfonate to yield reaction solution of p-tolyl hydrazine hydrochloride, its diluting to the concentration 43-45 g/l and condensation of the latter with acetoacetic acid amide at pH = 1.9-2.5 and in the mole ratio p-tolyl hydrazine to acetoacetic acid amide = (1:1):(1:1.1) in the presence of sulfamic acid taken in the amount 0.0029-0.0035 mole per 1 mole of the parent p-toluidine. Invention provides elevating yield of the end product and improving its quality. The yield of the end product is 92-93% as measured for p-toluidine, its melting point is 134.4oC and mass part of the basic substance is 99.5-99.7%. ^ EFFECT: improved preparing method, enhanced yield and improved quality. ^ 1 tbl, 7 ex |
