A-Azohydroperoxide

Tezuka s group (Tezuka and Ando, 1985 Tezuka et al., 1986) was able to isolate and characterize the benzenediazo ether of 1-naphthol (6.10). They stirred a solid mixture of the molecular complex 6.9 formed between an a-azohydroperoxide acid and benzene with an excess of 1-naphthol at room temperature in the dark for several hours. The separation of this solid by thin layer chromatography (silica gel, with a benzene-ethyl acetate mixture [9 1] as eluent) afforded the diazo ether 6.10 as a yellow oil in 17 % yield, together with 4- and 2-phenylazo-l-naphthol (6.11 and 6.12, 4% and 42%, respectively), 4-phenylbenzaldehyde (32%), benzoic acid (23%), and traces of other compounds (Scheme 6-6). Higher yields of the diazo ether (up... 

Various other oxidants have also been employed for N-oxidation of tertiary amines such as peracids [111], 2-sulfonyloxaziridines [112], and a-azohydroperoxides... 

Amine N-oxides can be prepared from amines with 30% aqueous hydrogen peroxide in a non-catalytic slow reaction (80, 90]. At elevated temperatures this oxidation proceeds at a reasonable rate and has been used in industrial applications. Various other oxidants have also been employed for N-oxidation of tertiary amines such as peracids [91], 2-sulfonyloxaziridines [92] and a-azohydroperoxides [93]. 

The photolysis of -azohydroperoxides in acetonitrile solutions of arenes gives rise to a different isomeric mixture of phenols in the presence or absence of oxygen (ref. 12). 

A soln. of startg. N-aryl-1,1-azohydroperoxide in benzene refluxed on an oil bath for 23 h with gentle bubbling of argon or N2 - product. Y 80%. Reaction is thought to occur via oxidation of the initially formed arylcyclohexadienyl radical. F.e.s. T. Tezu-ka et al., Tetrahedron Letters 30, 963-6 (1989). 

The syntheses of 1-amino-1-azocyclopropanes from enaminosulphonium salts and tosylhydrazides and of 1,1-azohydroperoxides from hydrazones, and an improved synthesis of mejo-azobis(a-phenylethane) from acetophenone azine have also been reported. 

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