325135-56-6Relevant articles and documents
Photoreduction of ortho-benzoquinones in the presence of para-substituted N,N-dimethylanilines
Chesnokov,Cherkasov,Checket,Nevodchikov,Abakumov,Mamysheva
, p. 1506 - 1511 (2000)
Photoreduction of o-benzoquinones irradiated at the wavelengths λmax ≈ 400 and 600 nm corresponding to the S(π→π*) and S(n→π*) electron transitions in the >C=O groups, respectively, in the presence of N,N-dimethylaniline and its derivatives was studied. The apparent rate constants of the photoreduction (kH) of o-quinones are determined by the free energy of electron transfer from the amine molecule to a photoexcited o-quinone molecule (ΔGe.t). The ΔGe.t values are calculated as the sums of the energies of the 0→0 transitions of the lowest triplet excited state of o-quinones, the reduction energies of o-quinones, and the oxidation energies of amines (the last two terms are numerically equal to the corresponding redox potentials). The maximum rate of photoreduction was found for ΔGe.t ≈ 0. The reaction mechanism is proposed, in which the reversible formation of a triplet exiplex is the rate-determining stage and hydrogen transfer proceeds in parallel with electron transfer within the exiplex.
