Abstract
DC and AC polarographic behavior of p-nitrophenol (PNP) has been studied in the presence of α- and β-cyclodextrin (a- and 8-CD); the concentration ratio of CD to PNP changed from 0 to 10 in acidic and basic solutions. Both α- and β-CD are adsorbed on the dropping mercury electrode. In acidic solution, in the presence of α-CD the reduction wave of PNP splits into two whose wave height ratio being 2: 1, The result has been intertpreted in terms of ECE reduction mechanism, viz, the dehydration reaction, followed by 4-electron reduction of PNP, is suppressed by the adsorbed film of α-CD. The second wave appears at the desorption potential of α-CD and the total wave height is diffusion controlled. In the presence of β-CD, a single 6-electron reduction wave appears at the potential Where β-CD is desorbed simultaneously. In basic solution, the reduction of PNP occurs after CD is desorbed. In both acidic and basic solutions, 6-electron total wave heights are diffusion controlled and decrease with increasing concentration of CD; this is attributed to the formation of PNP-CD clathrate compound. Dissociation constants of this clathrate compound in acidic and basic solutions were also determined.
