Polarographic studies on o-aminobenzenethiol

Abstract

Polarographic behaviour of o-aminobenzenethiol (RSH) is studied at dme in 0.1M-HClO₄, 0.1M-NaOH,Britton-Robinson buffers of different pH values and aqueous acetic acid. A well defined single wave is obtained in 0.1M-HClO₄ and buffers of pH 2.0 at all concentrations of the depolarizer whereas in all the other buffers, a well defined single wave is obtained only if the concentration is less than 2×10⁻⁴ M. In other cases, two waves are observed. With the increase in pH, theE _1/2 becomes more negative and finally attains a constant value. Thus the dissociation constant of sulphydryl group under the experimental conditions is 5.14. The diffusion coefficient in buffer of pH 2.0 is calculated to be 5.76×10⁻⁶ usingIlkovič equation.

The reaction is reversible and the oxidation product is a mercurous compound (RSHg) which converts quickly to (RS)₂Hg. Even in acetic acid media, well defined reversible anodic wave is obtained in all proportions of acetic acid and water.