Electronic effects of the azo group.
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
The electronic effects of the azo group have been examined in two ways. Part I. The rates of positive bromination of azoxybenzene and four azobenzenes have been measured in aqueous dioxane The results are interpreted in terms of partial rate factors and the Hammett equation. Electrophilic para-substituent constants (σp⁺) are derived for the phenylazo, 3-chlorop phenylazo, 3-bromophenylazo, 4-fluorophenylazo, and phenyl- ONN-azoxy substituents. A possible explanation is suggested for the discrepancy in the derived σp⁺ value of the phenylazo group with literature values. Part II. The ¹³C N.M.R. spectra of several substituted ethyl cinnamates, ethyl 4-arylethenylcinnamates, ethyl 4-arylazocinnamates, ethyl 3-arylazocinnamates, and azobenzenes have been measured in deuterochloroform. The attenuation of electronic effects by the 4-ethenylphenylene and the 3-and 4-azophenylene linkages is investigated. The chemical shifts of all carbon atoms in these compounds are discussed in terms of the Dual Substituent Parameter extension of the Hammett equation.