Collect. Czech. Chem. Commun. 1982, 47, 1112-1120

Carbon-13 and nitrogen-15 NMR spectra of cis- and trans-azobenzene, 4-monosubstituted and 4,4'-disubstituted trans-azobenzenes

Antonín Lyčka

Research Institute of Organic Syntheses, 532 18 Pardubice - Rybitví


13C and 15N NMR spectra of cis- and trans-azobenzene, 4-substituted trans-azobenzenes (N(CH3)2; NH2; OH; OCH3; CH3; Br; NO2) and 4,4'-disubstituted trans-azobenzenes (OH; NO2; NH2; OH; N(CH3)2, CH3; N(CH3)2, NO2) were measured. In comparison with trans-azobenzene, cis-azobenzene exhibits a downfield shift of nitrogen and C(1) signals and an upfield one of the C(2) and C(4) signals. The individual coupling constants nJ(15N13C) in 4-substituted and 4,4'-disubstituted trans-azobenzenes, respectively, have characteristic values and can be used for carbon signal assignment. With 4-substituted trans-azobenzenes, the 15N substitution chemical shifts of the nitrogen of the azo-bond were determined and their additivity in series of 4,4'-disubstituted trans-azobenzenes was proved.