| 摘要 |
Process for the preparation of pure 1-phenyl-3-carbalkoxy-5-hydroxypyrazoles of the general formula <IMAGE> (I) in which R denotes methyl or ethyl, by reaction of acetylsuccinic esters with phenyldiazonium chloride and a base with pKB value of 3.6 to -1.5 at a pH of 4 to 9 in an aqueous medium to give the corresponding phenylhydrazone, which is cyclized at a pH of 7 to 9.5, with warming and with the addition of ammonia, to give the ammonium salt of the hydroxypyrazole. Compound I is formed by acidification.
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