With Hydrogen Peroxide or 3-Chloroperbenzoic Acid

Oxidation of 4-(substituted methylene)pyrazol-3-ones 5()5a k with 30% hydrogen 

509 can be oxidized, respectively, with 30% hydrogen peroxide in acetic acid or one 

Oxidative cleavage of pyrazol-4,5-dione-4-[Af-(pyrazol-4-yl)]hydrazone 512 

515 and the Z z5pyrazole 516 in 72%, 0.5%, 10% and 17% yield, respectively. Oxidation of hydrazone 517 under similar conditions gave pyrazol-3-one diazonium salt 518 in 63% yield. The other components were not identified. 

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