The proton magnetic resonance spectra of conjugated aromatic hydrocarbons

Abstract

Abstract The proton resonance spectra of a number of alternant aromatic hydrocarbons are reported. With the exception of benzene and pyrene, two or more signals were obtained for each hydrocarbon. A probable assignment of the spectrum for each compound is given, and this was confirmed for anthracene and phenanthrene by deuteration. The spectrum of the non-alternant hydrocarbon azulene is also presented. The observed nuclear magnetic resonance spectra of the aromatic hydrocarbons cannot be interpreted on the basis of symmetry considerations or π-electron density, but are readily explained in terms of a simple model based on induced diamagnetic currents in the conjugated aromatic rings. The spectra calculated for each hydrocarbon on the basis of this model satisfactorily reproduce the main features of the observed spectra.