Polarographic Reduction of the Phenyl-Substituted Ethenes

Abstract

The polarographic behavior of the five phenyl-substituted ethenes (styrene, stilbene, 1,1-diphenylethylene, triphenylethylene, and tetraphenylethylene) at the dropping mercury electrode has been examined in dimethylformamide (DMF) and DMF-water solution containing 0.2M tetra-n-butylammonium iodide as background electrolyte on the basis of the various criteria for reversibility based on direct current polarography. Heterogeneous rate constants and ana values have been calculated on the basis of the spherical expanding electrode theory.None of the reversibility criteria predictions for the various possible mechanisms are entirely in accord with the experimental results. Although polar0graphic reduction of the phenyl-substituted ethenes is indicated to occur by processes which involved a change of electron transfer mechanisms, a definite decision regarding the actual mechanisms cannot be reached because of the lack of adequate theoretical bases for such a mechanism change and for the effects of variation in double layer structure on any given mechanism.

Polarographic Reduction of the Phenyl-Substituted Ethenes

“…Consequently, the present paper and the succeeding experimental study (9), in which the criteria discussed are applied to the behavior of the five phenyl-substituted ethenes, represent an attempt to determine the value of contemporary direct current polarographic theory when applied to the problem of the elucidation of mechanism for the polarographic reduction of organic compounds. Consequently, the present paper and the succeeding experimental study (9), in which the criteria discussed are applied to the behavior of the five phenyl-substituted ethenes, represent an attempt to determine the value of contemporary direct current polarographic theory when applied to the problem of the elucidation of mechanism for the polarographic reduction of organic compounds.…”

The electrochemical reduction of triphenylethylene in DMSO: a mechanistic study using mercury hemispherical microelectrodes

“…For the electrochemical reduction of phenyl-substituted ethylenes in aprotic solvents in general, a reaction mechanism involving two sequential electron transfers accompanied by disproportionation of the radical anion following the scheme below is found to be in operation where the relative stability of the radical anion to protonation renders the pathway formally DISP2 [8][9][10][11][12][13][14].…”

“…Of the most relevance to the current study are those literature reports on the electrochemical reduction of tetraphenylethylene (TPE) and triphenylethylene (TriPE) [8,9,11,14,[17][18][19]. The electrochemical reduction of TPE has been studied in dimethylformamide (DMF) [8,14,19], hexamethylphosphoric acid triamide (HMPA) [8] and acetonitrile (MeCN) [11].…”

“…Previous voltammetric studies on the reduction of TriPE have been carried out in aprotic solvents including dimethylformamide (DMF) [8,9,14,18], hexamethylphosphoric acid triamide (HMPA) [8], acetonitrile (MeCN) [11], and tetrahydrofuran (THF) [17]. Voltammetries in DMF and HMPA reveal two successive reduction waves corresponding to separate one electron transfers at the electrode, with reversibility observable only for the first wave.…”

Electrochemical Oxidation and Reduction of Allenes

“…Although allenes are isoelectronic with monoacetylenes and conjugated dienes, only the latter two families of compounds have been widely investigated electrochemically, mainly their cathodic reduction [1][2][3][4][5][6][7][8][9][10] and to a lesser extent their anodic oxidation [11][12][13][14][15][16]. In the following sections the electrochemical reactions of isomeric allenes, which have received scant attention, will be reviewed.…”