Electrochemical behaviour of some industrially important azonaphthol derivatives at glassy carbon electrode

摘要

Electroreduction of-N = N-and-NO_2 groups of azodyes,1-(4-nitro phenyl)-azo-2-naphthol(A),1-(3-nitrophenyl)-azo-2-naphthol(B),1-(2-nitrophenyl)-azo 2-naphthol(C)has been studied.The azo compound not containing-NO_2 group taken for the study was 1-(2-hydroxyphenyl)-azo-2-naphthol(D).The studies were carried out in partial aqueous media containing organic co-solvents such as acetonitrile,DMF and methanol.The substituent effect on cathodic reduction potentials E_(pc)in case of dyes A,B,C were studied and it was found to be in increasing order i.e.E_(pc(A))< E_(pc(B))< E_(pc(C)).During electroreduction of dyes A,B,and C,two separate quasireversible peaks,one for reductive cleavage of-N = N-groups,the other one due to reduction of-NO_2 group into-NH_2 groups were observed.The redox process has been compared with the cyclic voltammetry of the trial compounds,2-nitroaniline and 4-amino-3-hydroxy naphthalene-1-sulphonic acid.The other data such as effect of pH,concentration of active species,supporting electrolyte,scan rate on cathodic reduction peak potential and cathodic peak current has been determined.The process is found to be diffusion controlled.