Two iodo-organic compounds, iodochlorhydroxyquin and diiodohydroxyquin, were reduced at the dropping mercury electrode of a polarograph in nonaqueous systems. The diffusion current at various concentrations was determined. The currents produced were found to be diffusion controlled and applicable to a quantitative assay in the range of concentrations used.
HE POLAROGRAPHIC behavior of iodo com-Tpounds has been studied by Gergely and Iredale (1). They investigated reduction potentials of the iodobenzoic acids, iodoacetic acid, iodoanilines, and iodophenols in various media and buffers of controlled pH. The reduction potentials of the ionizable compounds that were studied were dependent on pH and the potentials of the unionizable compounds were independent of pH. They found that reduction involved two electrons in most cases. A compound such as o-iodobenzoic acid produced a double wave in one medium but only a single wave in another medium. They postulated that the double wave was due to partial dissociation of the compound in that medium. The double wave was diffusion controlled since the sum of the two waves was proportional to the concentration.
Colichman and Liu (2) investigated the polarographic properties of twenty-nine different iodo compounds. Their results were considered in terms of Hammett's linear free-energy relationship between structure and reactivity. They found that the proximity phenomenon of an artho substituent seemed to facilitate the polarographic reduction of the iodo group whether the ortho substituent was electropositive or electronegative. They reported half-wave potentials for all the compounds studied.
The relation between structure of aromatic halogen compounds and their reduction potentials was studied polarographically by Levin and Fodiman (3). Their work coniirmed what was previously learned from chemical experiments concerning the stabilities of carbon-halogen bonds. They found that a molecule containing chlorine atoms was reduced at a potential independent of whether this molecule was introduced