Phenylhydrazine, reaction with thermal decomposition

A systematic investigation of the phenylation of thiophene with phenyl radicals generated by different methods has been carried out (73IJS295). Phenyl radicals have been produced by the following methods (i) Gomberg reaction (ii) oxidation of phenylhydrazine (iii) thermal decomposition of AT-nitrosoacetanilide (iv) thermal decomposition of... 

Arylgold(III) complexes have also been obtained from the reactions of tetrachloroaurate(III) salts with substituted phenylhydrazines (303, 304). Thus were prepared the compounds R4N[AuCl3Ar] (R = Et or -Bu Ar = C6H5, p-ClC6H4, / -BrC6H4, or p-NC CsH, which were characterized by their H-NMR and vibrational spectra. Arylgold(III) species have been postulated as intermediates (3OS) in the thermal decomposition of [AuCl3(azobenzene)]. 

Pyridazines were obtained also by photolysis of 1-phenyl-l-vinyl azide in the presence of iron pentacarbonyl (3,6-di-phenylpyridazine was obtained in 1.1% yield) (78HCA589) or by thermal decomposition of an allenic hydrazonate (81JA7011). Acetylenic hydrazides can be transformed into pyridazines [84BSF(2)129], and thermal cyclization of dialkali metal salts of cu-hydroxyketone tosylhydrazones afforded pyridazines in moderate yield (85TL655). Propionyl phenylhydrazine, after reaction with 4-bromobutyronitrile, converts into a pyridazine (87SC1253). 

Carbohydrates that can exist in solution in an acychc form with a free aldehyde or ketone function react with three equivalents of phenylhydrazine to form bright yellow crystalline derivatives called phenylosazones, together with anihne and ammonia as the other products of the reaction. For example, a- and p-D-glucopyranoses 4 and 5 are in dynamic equilibrium in aqueous solution with the ring-opened form 3 (Sec. 23.2), which, because of its free aldehyde group, will react with phenylhydrazine to form the phenylosazone 17, as shown in Equation 23.6. Since phenylosazones are readily identified by either their melting points or temperatures of thermal decomposition, these derivatives may be used to characterize carbohydrates. 

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