1,2-bis-Phenylhydrazone

The oxidation of n-glucose phenylosazone by periodic acid has been shown to yield l-phenyl-4-phenylhydrazono-5-pyrazolone by the intermediate formation of the 1,2-bis(phenylhydrazone) of mesoxaldehyde. The reaction proceeds normally as if the osazone were acyclic it must be presumed, therefore, that there is an equilibrium between the cyclic (XII) and acyclic forms in the aqueous-ethanolic solutions employed,... 

A simple proof of the (1 —> 4)-linkage was obtained by periodate oxidation of 1 mole of lactose phenylosazone, which gave 1 mole of formaldehyde but no insoluble mesoxaldehyde 1,2-bis(phenylhydrazone) (11), a result that is typical of 4-0-substituted hexose phenylosazones (10) and that can be used for their diagnosis on a semi-micro scale. ... 

Formation of Pyrazoles from Bis(hydrazones).—Mesoxaldehyde bis(phenylhydrazone) (193), obtained by periodate oxidation of saccharide osazones (192) is readily cyclized in the presence of acids to give l-phenyl-4-phenylazo-pyrazole (195).162 365 Hexulose phenylosazones (192) are also disproportionaled in the presence of acidic salts of carbonyl reagents, such as hydroxylamine hydrochloride, to give l-phenyl-4-phenylazo-pyrazolin-5-one (196). The reaction probably proceeds via mesoxalic acid 1,2-bis(phenylhydrazone) (194).365 The hydroxalkyl derivatives of 196 are produced from dehydroascorbic acid bis(phenylhydrazone) by treatment with base to open the lactone ring and permit the conversion of 197 to 199.351,366 Another type of pyrazole that is formed by dehydrating osazones with acetic anhydride is discussed later under anhydroosazones (see Schemes 45,53). 

However, a base-catalyzed -elimination in the cyclohexane series, for example, of the inosose phenylhydrazone, may either stop on carbon-2 to give an arylazocyclohexene derivative (41) or, as for the inosose 1,3-bis(phenylhydrazone), proceed further leading to a complete aromatiza-tion (42). (An alternative free-radical mechanism that may explain the... 

Reactions of cyclic and acyclic 1,2,3-triones with phenylhydrazine give rise to mono- and bis-(phenylhydrazones). The central carbonyl group of a vicinal tricarbonyl system is electron-deficient and highly electrophilic,255 which is why treatment with an aryldiazonium ion affords 2-phenylhydrazones. The structure of such bis(phenylhydrazones) as cyclopentane-1,2,3-trione 1,3-bis(phenylhydrazone), dehydroascorbic acid 2,3-bis(phenylhydrazone), and cy-clobutanetetraone l,3-bis(phenylhydrazone) has been studied by UV, IR,1H-, 13C-, and 15N-NMR spectroscopy.265-268 Quantum-mechanical calculations to predict the most stable tautomeric forms of some 1,2- and l,3-bis(phenylhydrazones) revealed that the chelated bis(hydrazone) structure was usually more stable than the azoene-hydrazine structure.269-271 This does not mean that such structures do not exist, for example cyclobutanetetraone l,2,3-tris(phenylhydrazone) exists in a stable phenylazoene-hydrazine structure (see 49 Scheme 8).257-263... 

Fig, 13, Formation and periodate oxidation of n-lAreo-pentose phenylosazone. Xylose (1) was converted to the osazone (2) which was oxidized with periodic acid to yield formate and mesoxalaldehyde l,2-bis(phenylhydrazone) (3),... 

Example CH=N-NHPh 1 CH = N—NHPh HOCH HCOH HCOH i ch2oh D-araib/no-Hexos-2-ulose bis(phenylhydrazone)... 

Ligand abbreviations bi = 2,2 -bi-2-imidazoline bt = 2,2 -bi-2-thiazoline bpy = 2,2 -bipyridine phen = 1,10-phenanthroline phy = l,10-phenanthroline-2-carbaldehyde phenylhydrazone bpp = 2,6-bis(pyrazol-3-yl)pyridine paptH = 2-(2-pyridylamino)-4-(2-pyridyl)thiazole 2-pic = 2-picolylamine L = macrocyclic ligand derived from condensation of 2,6-diacetylpyridine with 3,6-dioxaoctane-1,8-diamine Hjthpu = pyruvic acid thiosemicarbazone Hjthpx = pyridoxal thiosemicarbazone salen = dianion of W,iV -ethylenebis(salicylideneimine) H2fsa2en = dianion of fV,JV -ethylenebis(3-carboxysalicylaldimine). 

See Oxygen Cyclohexane-1,2-dione bis(phenylhydrazone) See Other a-PHENYLAZO HYDROPEROXIDES... 

Diketo-mj/o-inositol, bis(phenylhydrazone) (XCVI) 217 d. -250 - —222 EtOH-C6H6N 36... 

Anhydro-l-phenylimino-2,4,5-triphenyl-l,2,3-triazolium hydroxide (178), obtained by oxidation of benzil bis-phenylhydrazone, affords 1 1 cycloadducts with a wide variety of alkynic and alkenic dipolarophiles, yielding pyrazolino[2,3-c]- and dihydropyrazolino[2,3-c]-[l,2,3]triazoles (179). The initial 1 1 cycloadduct (180) obtained from (178) and carbon disulfide undergoes thermal fragmentation to give 2,4,5-triphenyl-l,2,3-triazole (181)... 

Iactone. The observed low frequency is probably caused by hydrogen bonding of the lactone carbonyl with the imino proton of the hydrazone residue on C2, as shown by NMR spectroscopy. The same low frequency band also appeared in the spectra of the bis(arylhydrazones) of other analogues (42,46) such as the phenyl analogue of DHA [4-phenyl-butano-1,4-lactone 2,3-bis(phenylhydrazone)], which cannot form a 1,5-lactone. Finally, the lactone ring size was also deduced from its chemical reactions (24). 

---