The redox reactions of quinones have been the subject of many studies over the years and they continue to be of interest to electrochemists. In a study of methane (1,I-dimethyl-3,5-cyclohexanedione) by E. Kariv, J. Hermolin, and E. Gileadi (Electrochem. Acta 16, 1437 (1971)), the following current-voltage data were obtained for the reduction of the quinone in anhydrous butanol on a mercury electrode:

(a) How well do these data fit the empirical Tafel equation?

(b) The authors postulate that the reduction product is the dimer HMMH formed by the following mechanism (where the quinone is denoted M):

(1) M (sol) Mf ads)

(2) M (ads) + H + c ?7MH (ads)

(3) MH (ads) + MH (ads) ? HMMH the affixes sol and ads refer to species in solution and on the surface of the electrode, respectively. Does this mechanism help to explain the current-voltage data?

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-E/V j/(A m²²) 1.50 1.58 10 30 1.63 50 1.72 1.87 100 1.98 200 250 22.10 290