The polarographic reduction of conjugated hydrocarbons: II. The reduction of 1,n‐diphenylpolyenes

Abstract

Abstract The current‐voltage curves of some 1,n‐diphenylpolyenes were measured in a 0.175 molar solution of tetrabutylammoniumiodide in 96% dioxanewater at 25° and 75° C. The experimental half‐wave potentials and the roots a of the M.O. secular equation, corresponding to the lowest non‐occupied π‐electronic level of the conjugated systems, fit the linear equation: ϵ 1/2 = a · γ − 1.05 Volts, discussed in part I, giving a mean value of y¯ = − 2.18 ± 0.04 ev (stand, dev.). The theoretical discussion of the course of the reduction of conjugated hydrocarbons has been extended, taking into account the effect of the methylene group on the π‐electronic distribution in the intermediately formed radical ions. From a comparison between the results of these theoretical approximations and the experimental data some reasonable suppositions have been made about the behaviour of these polyenes and their partial reduction products at the dropping mercury electrode during electrolysis.