Spectrophotometric and electrochemical studies of the interaction of cryptand 222 with DDQ and I2 in ethanol solution

Abstract

Spectrophotometric and electrochemical studies concerning the interaction of cryptand 222 with DDQ and I₂ have been performed in ethanol solution. In the case of DDQ, the results are indicative of the formation of C222⁺ and DDQ^- through an equilibrium reaction. The results of I₂ indicate the formation of I₂-ethanol complex and I₃^- in the absence of C222. In the presence of C222, the formation of C222I⁺ and I₃^- through a non-equilibrium reaction is confirmed. The equilibrium constant of the redox reaction between DDQ and C222 has been calculated from the absorbance mole ratio data, using the nonlinear least square program “KINFIT”. The electrochemical reversibility of I^-/I₂ couple and irreversibility of DDQ/DDQ^- is indicated by amperometry. The behavior of DDQ and I₂ has been compared. A comparison with aprotic solvents has also been made.

KEY WORDS: Spectrophotometry, Electrochemistry, Cryptand 222, DDQ, I₂

Bull. Chem. Soc. Ethiop. 2006, 20(2), 183-192.