Bischoff, Christian et al. published their research in Journal fuer Praktische Chemie/Chemiker-Zeitung in 1994 | CAS: 51395-52-9

4-Bromo-3-methyl-1H-pyrazol-5(4H)-one (cas: 51395-52-9) belongs to pyrazole derivatives. An alternative way to synthesize multisubstituted pyrazoles is the Csingle bondH arylation of simple pyrazoles. The pyrazole ring is resistant to oxidation and reduction but the groups, such as alkyl and formyl attached to the ring, are oxidized to respective acids. Only electrolytic oxidation, ozonolysis, and a strong base cause ring opening.Computed Properties of C4H5BrN2O

Oxidation of pyrazolinones was written by Bischoff, Christian;Ramm, Matthias;Schroeder, Edith;Jancke, Harald. And the article was included in Journal fuer Praktische Chemie/Chemiker-Zeitung in 1994.Computed Properties of C4H5BrN2O This article mentions the following:

Oxidation of pyrazolinones I (R = H, Ph, CONH2) with H2O2/HCOOH gave dimer II which underwent cleavage on treatment with either phenylhydrazine or Br2 to pyrazolinones III (Q = :NNHPh, Br, resp.). In the experiment, the researchers used many compounds, for example, 4-Bromo-3-methyl-1H-pyrazol-5(4H)-one (cas: 51395-52-9Computed Properties of C4H5BrN2O).

4-Bromo-3-methyl-1H-pyrazol-5(4H)-one (cas: 51395-52-9) belongs to pyrazole derivatives. An alternative way to synthesize multisubstituted pyrazoles is the Csingle bondH arylation of simple pyrazoles. The pyrazole ring is resistant to oxidation and reduction but the groups, such as alkyl and formyl attached to the ring, are oxidized to respective acids. Only electrolytic oxidation, ozonolysis, and a strong base cause ring opening.Computed Properties of C4H5BrN2O

Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics