Voltammetry of electroactive oil droplets:: Electrochemically-induced ion insertion, expulsion and reaction processes at microdroplets of N,N,N′,N′-tetraalkyl-para-phenylenediamines (TRPD, R = n-butyl, n-hexyl, n-heptyl-and n-nonyl)

The electrochemistry of microdroplets, shown to be nearly monodisperse, of N,N,N',N'-tetraalkyl-para-phenylenediamine oils (TRPD, R = n-butyl, n-hexyl, n-heptyl, and n-nonyl) immobilized on a basal plane pyrolytic graphite electrode and immersed into aqueous electrolyte solution is studied using cyclic voltammetry. Upon oxidation of the TRPD droplet to the cation radical TRPD+., anion uptake from, or cation loss into the aqueous solution takes place, so as to maintain electroneutrality within the oily deposit. The former process is shown to produce an ionic liquid, with the anion insertion taking place at the triple phase boundary of electrode \TRPD oil\ aqueous electrolyte; the latter process, in contrast, takes place at the interface between the two immiscible liquids, and with two-thirds-order kinetics. The possibility of a chemical reaction taking place between the electrogenerated and. inserted ions at the three-phase junction, viz. redox-catalysis or otherwise; is illustrated via reference to two systems (azide and iodide).