Property of the O-2p-Electrons of Dibenzofuran (Part 1) -Electronic Spectra of Dibenzofuran-

Abstract

The electronic spectra of dibenzofuran derivatives were observed. The spectrum of dibenzofuran has main peaks at 3O^2-.1, 287.1, and 249.7 nm in cyclohexane. They have been assigned to be Lb, L, , and B transitions respectively by using the results of solvent and substituent effects. The Lb band is short axis-polarized, shows blue shift in acidic solvents, and is most affected by the substituent at the 2-popition of dibenzofuran. The correlation of the wave number with the resonance parameter of substituent was expressed as v (kK) =33.10-4.17 The L. band is long axis-polarized, and is affected by the substituent at the 3-position of dibenzofuran. The correlation was expressed as v (kK) = 34.83 3.99.1a, 1 The Lb band of dibenzofuran and its analogues (fluorene, dibenzothiophene, etc.) were closely related to the p-orbital electronegativity of heteroatoms and the aromaticity of the five-membered ring. The interaction of oxygen with the aromatic ring was discussed.