Chemistry of Polynuclear compounds

Abstract

In an investigation into the coking mechanism of coal, polynuclear quinones were adopted as models. The infra-red absorption spectra (between 2000 and 650 cm^-1) are now reported for several of these quinones, namely : dibenzanthrone (I) ; isodibenzanthrone (II) ; 16,17-dimethoxydibenzanthrone (III) ; 16,17-diethoxydibenz-anthrone (IV) ; pyranthrone (V) ; flavanthrone (VI) ; 4,lO-dibromoanthanthrone (VII) ; 4,4'-dibenzanthronyl (VIII) ; 2.2'-dimethyl 1,1'-dianthraquinoyl (IX) ; and for the polynuclear aromatic hydrocarbons violanthrene (X) and isoviolanthrene (XI). Factors influencing the quinonoid carbonyl group bond order (hence frequency of absorption) and the redox potential are discussed. Tentative correlations are advanced for strong absorption bands in the CH out-of-plane vibration region. The carbonyl group frequencies and the electronic absorption spectra indicate the molecular non-planarity of VIII and IX.