226998-69-2Relevant academic research and scientific papers
The kinetics and thermodynamics of quinone-semiquinone-hydroquinone systems under physiological conditions
Roginsky, Vitaly A.,Pisarenko, Leonid M.,Bors, Wolf,Michel, Christa
, p. 871 - 876 (1999)
The steady-state concentration of semiquinones (Q·-) determined by EPR in the mixtures of eleven alkyl-, methoxy-and chloro-substituted 1,4-benzoquinones as well as 1,4-naphthoquinone (Q) with corresponding hydroquinones (QH2) in aqueous buffer. pH 7.40, was used to calculate a constant for equilibrium (1) Q + QH2?Q·- + Q·- + 2H+ (k1; 2k-1; K1 = k1/2k-1). The rale constants for comproportionation between Q and QH2, k1, were calculated from the combination of K1 determined in this work and 2k-1 reported previously. The Nernst equation was applied to calculate the change in one-electron reduction potential ΔE1 = E(Q/Q·-) - E(Q·-/QH2) in equilibrium (1). The E(Q·-/QH2) values were calculated from ΔE1 and the values of E(Q/Q·-) known from the literature. The correlations between E(Q·-/QH2) and E(Q/Q·-) as well as between ΔE1 (k1) and E(Q/Q·-) are discussed. The values of ΔE1 and k1 are suggested to be the key factors governing the autoxidation of QH2.
