Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

Two-parameter regression including the acceptor number (AN) and permittivity (ε) of the solvent explains to some extent the solvatochromic shift of the absorption band of benzophenone radical anion (Ph₂C^•-O^-) in the visible region. In 11 dipolar aprotic solvents characterized by ε > 10, in which the Ph₂C^•-O^- anions are not associated with (C₂H₅)₄N⁺ cations (the radicals were prepared by cathodic reduction of benzophenone in the presence of (C₂H₅)₄N⁺ClO₄^- as electrolyte) a correlation equation has the form ν_max (in cm^-1) = 86.2(AN) - 19.7 · 10³[(ε - 1)/(2ε + 1)] + 21.32 · 10³. It reflects the relative stabilization of the ground state in a medium with a high acceptor number and an increase in the dipole moment of Ph₂C^•-O^- during excitation.

Keywords: Benzophenone radical anion; Electronic absorption spectroscopy; Solvent effects; Ketyl radicals; Ketones; Solvatochromism; Electroreductions.

References: 18 live references.