In continuation of the polar0 described in Part 1, the electrochemical oxi &? phic. oscillopolarographic and coulometric studies tions of l-diazo-2.3.4.5-tetraphenylcyclopentadiene (A), p-phenyl-diphenyldiazomethane (B), diphenyldiazomethane (C), p-nitro-diphenyldiazomethane (D), p-nitrophenylmethyl-diazoxnethane (E), pmitrophenyl-diazomethane (F), 9-diazofluorene (G), phenyl-benzoyl-diazomethane (H) andp-nitrophenyl-benzoyI-diazometbane (J) have been investigated in LiClO,/acetonitrile solution by measurements at a rotating platinum ring-disk electrode and by recording the Kalousek polarograms. In comparison with the reversible anodic wave of diphenylpicrylhydrazyle at +0*69 V(sce) the electrochemically initiated chain reaction of the aromatic substituted diazomethane derivatives B to G causes a considerable degradation of the shielding efficiency S of the ring-disk electrode. This is an example for the fact that, in addition to the collection efficiency N, the value of S can also be used as criterion of the mechanism of an electrode reaction. Because the lifetime of the primary electrochemical products is diminished by irreversible reactions, a degradation of the collection efBciency N has also been observed. The graduation of the stability of the diazonium radical ions II following from the values of N is confirmed by the quotients icsta/ &nod of the Kalousek polarograms and can be ex ! effects of the substituents bonded to the diazo car lained qualitatively by mesomeric and inductive on atom. Current/potential curves of diphenyldiazomethane, measured at the rotating platinum ring-disk electrode and at the rotating disk electrode using a Kalousck commutator, are discussed. R&au&-En continuant des recherches polarographiques. oscillopolarographiques et coulombriques de l'oxydation dlectrocbimique de l-diazo-2.3.4.5-t&raphenyle-cyclop&ntadi&ne (A), p-phenylediphenyle-diazomtthane (B), diphbnyle-diazomethane (C), p-nitro-diphenyle-diazomethane (D), p-nitroph6nyle-methyle-diazomkthane (E), p-nitrophenyle-diazomethane (F), 9-diazofluorene (G), phenylebenzoj[le-diazomethane (H) et p-nitrophenyle-benzoIle-dlazomethane (J) en ac&onitrile en presence de perchlorate de lithium comme 6lectrolyte indifferent d&rites dans la premiere partie, on presente des m&a-ages a l'blectrode tournante & disque et a anneau et des polarogrammes d'apr& * Manuskript eingegangen am 7 Juli 1969.