Abstract
The results of the investigation on the electrolytic reduction potential of p-aminoazobenzene with the polarograph and dropping mercury cathode at 25°C were as follows.
(1) Reduction potential of p-aminoazobenzene was more positive in lower concentration than that in higher concentration in every PH solution.
(2) Owing to the weak basic property of p-aminoazobenzene, there were two reduction potentials which were due to the dissociated and undissociated forms in some proper acidic solutions. In high acidic solution, p-aminoazobenzene changed to quinoid form which was demonstrated by spectrographic study. The reduction potential of quinoid form was more positive than that of azoid form and further, that of dissociated form more posi tive than that of undissociated form.
(3) The reduction potential of p-aminoazobenzene which substituted NH2 group in azobenzene was more negative than that of the latter. This is expected from our negativity rule of electrolytic reduction.
(4) The solubility of p-aminoazobenzene in water at 25°C was found to be 2.815•10-4g. mol per litre calculated by the result of polarographic measurement.
