Infrared Spectra of Some Substituted Monoazobenzenes, Hydroxyhydrazone Tautornerism in Orthohydroxy, and Orthoarninoazobenzenes

Author： Afifi M. S. Tera F. M. Sayed A. M. B.

Publisher： Society for Applied Spectroscopy

ISSN： 0003-7028

Source： Applied Spectroscopy, Vol.36, Iss.6, 1982-11, pp. : 682-684

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Abstract

The infrared spectra of substituted monoazobenzenes (O-Cl, m-Cl, p-Cl, p-Br, 2,5-dichloro, O-NO₂, m-No₂, p-NO₂, and 2,4-dinitro) derived from p-hydroxy, O-aminobenzenes (series A), and of the substituted monoazobenzenes (O-Cl, m-Cl, p-Cl, 2,5-dichloro, p-Br, and O-NO₂) derived from p-amino, O-hydroxybenzene (series B) have been recorded and tentatively assigned. In series A the O-NO₂, m-NO₂, and 2,4-dinitro compounds and all members of series B show a relatively intense IR band at 1651 ± 17 cm^-1. The appearance of this band in the nitrocompounds of series A at 1654 ± 14 cm^-1 is interpreted as being probably due to coupling of δNH₂ and α as NO₂. The band at 1642 ± 8 cm^-1 in series B is tentatively as signed as a v C==O absorption. This interpretation is regarded as evidence of tautomeric equilibrium in series B of these azodyes.