Polarographic studies on some organic compounds of arsenic. Part IV. Diphenylarsinic acid

Abstract

A study has been made of the polarographic behaviour of diphenylarsinic acid. It gives rise to a single cathodic wave below pH 6, displaying an adsorption pre-wave, and some limited inhibition effects. The latter are removed by addition of a surface-active agent, thus yielding a well formed, diffusion-controlled wave, the height of which is proportional to concentration (up to 1 × 10^–3M) and independent of pH. The current-potential relationships and the reduction mechanism are discussed. An irreversible reduction to tetraphenyldiarsine has been found. The use of polarography is proposed for the quantitative determination of diphenylarsinic acid. In mixtures with phenylarsonic acid and/or triphenylarsine oxide, the wave at pH 1 gives the total concentration of all three, while that at pH 5.3 gives the concentration of diphenyl and triphenyl species and that at pH 7 triphenylarsine oxide alone.