¹H and ¹³C NMR study of 8‐hydroxyquinoline and some of its 5‐substituted analogues

Abstract

Abstract 1 H and 13 C NMR spectra of 8‐hydroxyquinoline (oxine) and its 5‐Me, 5‐F, 5‐Cl, 5‐Br and 5‐NO 2 derivatives have been studied in DMSO‐ d 6 solution. The 1 H and 13 C chemical shifts and proton–proton, proton–fluorine, carbon–proton and carbon–fluorine coupling constants have been determined. The 1 H and 13 C chemical shifts have been correlated with the charge densities on the hydrogen and carbon atoms calculated by the CNDO/2 method. The correlation of the 1 H and 13 C chemical shifts with the total charge densities on the carbon atoms is approximately linear ( r H 2 = 0.85, r C 2 = 0.84). The proton in peri position to the nitro group in 5‐NO 2 ‐oxine is an exception.