Chemistry of polynuclear compounds. II. The behaviour in concentrated sulphuric acid solution and absorption spectra of some polynuclear quinones

Abstract

In an investigation into the coking mechanism of coal, polynuclear quinones were adopted as models. The electronic absorption spectra of dibenzanthrone (I) ; 16,17-dimethoxydibenzanthrone (II) ; 16,17-diethoxydibenzanthrone (III) ; 16-methoxy-17-ethoxydibenzanthrone (IV) ; 16-methoxy-17-hydroxydibenzanthrone (V) ; and 16-ethoxy-17-hydroxydibenzanthrone (VI) in chlorobenzene and dioxane solution were measured and are discussed. Nan-planar configurations are proposed for II-VI and the possibility of the same for I considered. The electronic absorption spectra in concentrated sulphuric acid of I, II, V, and VI were measured and are discussed. IV, V, and VI are new vat dyes ; V is produced by the action of concentrated sulphuric acid on II and IV, and VI is produced by the same reaction with III. IV is prepared by the methylation of VI. The electronic absorption spectra of anthraquinone and some derivatives were measured in concentrated sulphuric acid and are discussed in conjunction with some of the above spectra. The infra-red spectra of IV, V, and VI confirm the identification of these compounds as 16,17-disubstituted dibenzanthrones and establish the nature of the alkoxyl substituents ; the quinonoid-carbonyl frequencies are discussed.