Patents Assigned to Chemie Linz G.m.b.H.
  • Process for the preparation of pure 1-phenyl-3-carbalkoxy-5-hydroxypyrazoles
    Patent number: 4837335
    Abstract: Process for the preparation of pure 1-phenyl-3-carbalkoxy-5-hydroxypyrazoles of the general formula ##STR1## in which R denotes methyl or ethyl, by reaction of acetylsuccinic esters with phenyldiazonium chloride and a base with pK.sub.B 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.
    Type: Grant
    Filed: April 4, 1988
    Date of Patent: June 6, 1989
    Assignee: Chemie Linz G.m.b.H.
    Inventors: Hubert Stuckler, Wilhelm Dobramysl