Struktur und reaktivität aliphatischer diazoverbindungen—X. Untersuchungen zum mechanismus der elektrochemischen oxydation aliphatischer diazoverbidungen, teil 1

Abstract

The anodic oxidation of 1-diazo-2.3.4.5-tetraphenylcyclopentadiente (A), p-phenyl-diphenyldiazomethane (B), diphenyldiazomethane (C), p-nitro-diphenyldiazomethane (D), p-nitrophehyl-methyl-diazomethane (E), p-nitrophenyldiazomethane (F), 9-diazofluorene (G), diazomethane (H) and ethyl diazoacetate (J) has been studied in acetonitrile solution containing lithium perchlorate as supporting electrolyte. The half-wave potentials of the first anodic wave measured at a rotating platinum-disk electrode are shifted to more negative values the more the electron density of the diazo carbon is increased by electron-releasing substituents and the better the primary product of the electrode reaction is stabilized by mesomeric effects of aromatic groups. The oscillopolarographic curves d E/d t = f( E), also measured at the rotating platinum-disk electrode, prove that diazonium radical-cations are the primary oxidation products of the compounds A-G. As final products of the anodic decomposition of the diazo compounds B-G the corresponding olefins are isolated with good yield. Coulometric measurements showed that with increasing concentration of the diazo compounds only between 0·20 and 0·03 faradays per mole are necessary for the quantitative decomposition. These results must be attributed to a chain reaction initiated by the diazonium radical-ions. As concluded from polarographic and oscillopolarographic measurements of diphenyldiazomethane, a carbonium radical-ion seems to be a further intermediate compound of this reaction.