Spectral and Cyclic Voltammetric of Oxidized Products of 10-[4?-(N-Diethylamino)Butyl]-2-Chlorophenoxazine and its Applications in Redox Titrimetry

Abstract

Abstract. 10-[4 H -(N-diethylamino)butyl]-2-chlorophenoxazine (DBCP) undergoes a reversible one-electron oxidation with cerium (IV) to form a pink coloured radical cation [DBCP Á ] in the presence of stoichiometric amounts [DBCP: Ce(IV) 1:1] of the reactants. The radical cation underwent a second oneelectron oxidation to form a brownish yellow coloured dication [DBCP 2 ] in the presence of more than one equivalent of cerium(IV), which was characterized by UV-vis, IR and mass spectrometry. The cyclic voltammogram of DBCP exhibited two anodic waves at 721 mV and 1158 mV and two cathodic waves at 653 mV and 1076 mV at a scan rate of 24 mV/s. The peak at 721 mV corresponds to the oxidation of DBCP to the radical cation [DBCP Á ] and the second anodic peak at 1158 mV stands for the oxidation of the radical cation to the dication [DBCP 2 ]. Bromine oxidizes DBCP to three products as evidenced by HPLC and the tentatively predicted structures based on the massspectral data support the formation of brominated oxidized products. In order to explore the analytical applications, the optimum conditions for the successful use of DBCP as a redox indicator in the macro and micro estimation of ascorbic acid, methionine, isoniazid, phenylhydrazine hydrochloride and biotin using chloramine-B as oxidant, have been developed. The indicator gives sharp and stoichiometric end-points.