6533b86dfe1ef96bd12ca267

RESEARCH PRODUCT

Preparation, separation and identification of some para-substituted ONN and NNO trans-azoxybenzenes

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description

A series of para-substituted azoxybenzenes was obtained as model compounds for the investigation on the mechanism of Wallach rearrangement. Oxidation of azobenzenes with hydrogen peroxide in acetic acid solution, provided mixtures of α and β isomers. Some couples of the products were separated, using chromatography and crystallization techniques, and identified on the basis of their carbon NMR and mass spectra. The SCSD algorithm can be applied to the interpretation of the 13C-NMR spectra. Recognition of the ipso and para carbons suffice to the identification of an isomer, hence there are no strong interactions between the azoxy group and another substituent across the aromatic ring. Fragmentation of azoxybenzenes under electron impact occurs preferentially on the oxidized side of the azoxy bridge. Relative intensities of daughter ions differentiate the ONN = α and NNO = β isomers in most cases.