METHOD OF SYNTHESIS OF 1-PHENYL-3-METHYL-PYRAZOLONE-5 Russian patent published in 2002 - IPC

FIELD: organic chemistry, chemical technology. SUBSTANCE: invention relates to synthesis of pyrazolones. 1-Phenyl-3-methyl-pyrazolone-5 is synthesized by condensation of acetoacetic acid ester and phenyl hydrazine followed by cyclization reaction of phenylhydrazone formed being reaction is carried out in acid medium at increased temperature. Isolation of final substance is carried out for two stages. On the first stage aliphatic or aromatic hydrocarbon with boiling point above 90 C is added to methanol solution of reaction mass and the main part of 1-phenyl-3-methylpyrazolone-5 is separated by filtration as precipitate. On the second stage the remained phenylmethylpyrazolone is isolated from filtrated obtained on the first stage and after alcohol distillation from filtrate and recovered to the main separation stage. EFFECT: increased yield, enhanced quality of end product. 2 ex