Pulse radiolysis of nitrobenzene solutions

Abstract

The absorption spectra of the radicals HC₆H₅NO₂ and OHC₆H₅NO₂ in aqueous solutions have been obtained. These transients have a strong absorption at 4100 Å and their molar extinction coefficients are both 3700 M^–1 cm^–1. The following rate constants have been measured : k(H+C₆H₅NO₂)=(5.6±0.6)× 10⁹ M^–1 sec^–1; k(OH+C₆H₅NO₂)=(4.7±0.5)× 10⁹ M^–1 sec^–1; k(O₂+OHC₆H₅NO₂)=(2.3±0.3)× 10⁶ M^–1 sec^–1; k(OHC₆H₅NO₂+OHC₆H₅NO₂)=(6.0±0.4)× 10⁸ M^–1 sec^–1. About 25% of the reactions between two nitro-hydroxycyclohexadienyl-radicals lead to nitrophenol-isomers by disproportionation. The majority of these reactions lead to other products (probably dimers by combination) which exist in acid and basic forms, the latter having strong absorptions in the visible range. These products are believed to be derivatives of nitro-cyclohexadiene.