In 95% ethanol, phenylhydroxylamine is oxidized to nit,rosobenzene and can further react, with the nitrosobenzene thus formed to form azoxybenzene. .lzobenzene can be detected occa>ionally as an intermediate oxidat,ion product of phenylhydroxylamine cawed by react,ion of the latter with azoxyhenzene. The difference b e t m e n the reduction and oxidation E,] values of nit,rosobenzene arid phenylhydroxylamine, reh1)ectively. i:, larger at the rotating P.G.Is appear to be lower t,han those for the t'urbidimetric technique, but before valid conclusions can be drawn a more complet,e study of t,he two methods in identical media should be made. The results were used to adjust solution concentration so that studieq could be made when micelles were either present or absent. The presence of micelles of the electroactive species in solution causes a great change in the physical size of the diffusing species. The diffusion of micelles and the monomer to the electrode on a weighted average tiasis would be much slower than the monomer alone. This effect is felt to tie the primary reason for the decrease of i,,/C or I with concentration shown in Table XI. Values for the average diffusion coefficient (D) of DDAO in 0.2.11 NaCl as a function of bulk concentration obtained by open end capillary measurements (10) are shown in Table IT. T'ne D in this case, too, is an average value for both the monomer and micelle. Limiting current values calculated on the basis of D1'2values in Table IV were higher by about 10% on the average, however, than the limiting current values measured. The values of D shown in Table IF7 were taken in a neutral solution of
0.23' KaCl and t,he polarographic study was done at pH 2 and in ionic strength 0.34. I t has been shown by Herrniann ( 5 ) that the micelle molecular weight increases in acid solution for DDAO cation. This increase in molecular weight would lower t'he value for D , thereby decreasing the limiting current further. Since D's in the polarographic media were not det,ermined by an independent means, it is impossible to calculate expected current values. aiseries of studies were made to show the relation of limiting current wit,h mercury colurnn height. If the above phenomenon is the cause of the current concentration relation observed, the limiting current should nevertheless be diffusion controlled unless dissociation of micelles is important. Measurements were made above and below the est,imated critical micelle concentrat,ion. Intercept,s of i d LIS. h1I2plots were linear and passed through the origin for 0.3mJI DDAO (
