Osazone phenylhydrazone

An identical compound is formed from benzil by the action of phenylhydrazine, and from benzaldehyde phenylhydrazone by autoxida-tion (Busch). The formation of osazones from a-hydroxyketones (and a-hydroxyaldehydes) will be discussed later (p. 298). 

Many oxidizing agents have been used, especially copper sulfate and other cupric salts. Potassium dichromate in acetic acid and manganese dioxide are good oxidants for benzil bis(phenylhydrazone). Nitrous acid has been used for the osazones of acetylated sugars and for phenylglyoxal bis(phenylhydrazone). ... 

Another 2,3-bis(phenylhydrazone), namely, l,5 4,6-dianhydro-2,3-hexodiulose bis(phenylhydrazone) (62a), was also found to cyclize to a pyrazoline (63a) by the action of copper(II) sulfate or benzalde-hyde, which usually convert osazones into aldosuloses or osotria-zoles.65 Reduction of this bicyclic compound (63a) led to the pyrazo-lidine 64, and periodate oxidation of 63a gave the expected aldehyde 65. 

Another type of substituted pyrazole is obtained by refluxing osazones with acetic anhydride during the acetylation, two molecules of water per molecule are removed. The structure of the resulting 5-(D-g/ycero-diacetoxyethyl)-3-formyl-l-phenylpyrazole 2-acetyl-2-phenylhydrazone (71) was determined by deacetylation followed by oxidation with (a) periodate to a pyrazolaldehyde (72), and (b) permanganate to the known l-phenyl-pyrazole-3,5-dicarboxylic acid (73), as well as by a study of its n.m.r. spectrum, which confirmed the pres-... 

Deoxyglucose forms an osazone with 3 mol of PhNHNH, but 2-deoxyglucose has no C OH and forms only a phenylhydrazone. 

Electron Spin Resonance Studies of Chemical Changes of Phenylhydrazones and Osazones in Alkaline Solution... 

Figure 2. Electron spin resonance spectra of sugar phenylhydrazones and osazones (2.5 mM to 3.5 mM, in Me2SO-l% K-tert-BuO)...

Table I. Free Radicals from Sugar Phenylhydrazones and Osazones in Methyl Sulfoxide-1 % Potassium ferf-butoxide at 25 zt 3°C...

Radical concentration, based on starting phenylhydrazone or osazone, was determined by comparison with the Fremy s salt standard solution (15), measured in methyl sulfoxide—1 % K-terJ-BuO. 

The solutions were examined in a Varian model V-4548 aqueous solution sample cell. All experiments in solution required a trace of oxygen. Freshly prepared solutions of phenylhydrazones or osazones (0.1 to 3.5 mM) in methyl sulfoxide were mixed with base [1 to 3% (90 mM to 270 mM) potassium terf-butoxide in methyl sulfoxide] and exposed to air for about 30 sec. Initial ESR spectra were recorded in about 30 sec after mixing. 

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