Investigation of aromatic heterocycles

The results of an analysis of the UV and IR spectra confirm the previously drawn conclusion regarding the aromatic character of 1,2,5-oxadiazole derivatives. The spectral properties of naphth-1,2,5-oxadiazole and phenanthrene are similar; saturation of the double bond between the 4- and 5-carbon atoms of the naphthalene ring disrupts conjugation with the heterocyclic fragment. The introduction of a sulfo group into the 5-position does not substantially change the frequencies and distribution of the IR absorption bands. A difference in the effect of hydroxyl groups in the 7- or 8-positions is revealed. The spectral effects that accompany transition from arene-1,2,5-oxadiazoles to their N-oxides are analyzed.See [1] for communication XIV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1036–1042, August, 1971.