Refractometric Assessment of π-Electron Delocalization and Aromaticity in Polycyclic Aromatic and Unsaturated Hydrocarbons

The results of precision measurements of the renewed optical exaltation, which allows quantitative assessment of the degree of π-electron delocalization in unsaturated and (poly)cyclic aromatic hydrocarbons, are presented and discussed for the first time. Correlations were established between the renewed exaltation of molar refraction in a series of unsaturated and polycyclic aromatic hydrocarbons and known conjugation parameters, including their electronic molecular structure, the number of π-electrons involved in conjugation, their electronic absorption spectra, and resonance energy. The resulting correlation equations were used to predict the refraction constants and evaluate the aromaticity of acenes.