The effects of substitution on the electrochemical reduction of naphthacenetetrone in N,N-Dimethylformamide

The polarographic reduction of 5,6,11,12-naphthacenetetrone (NT) and several of its chloromethyl, and nitro derivatives were investigated. The electrochemical behavior of NT was compared with 6, 11-dihydroxy-5, 12-naphthacencequinone (DHNQ) previously studied. Like DHNQ, NT exhibits two reduction waves in N,N-dimethylformamide. However, two additional post adsorption waves which were not present in DHNQ reduction were also observed. The first step reduction of NT, representing the formation of the radical anion NT^?, has a potential (0.01 V vs sce) much more anodic than that of its DHNQ counterpart ( ?0.75 V vs sce). The substituent effects of NTs were noted. A linear Hammett relationship similar to that of the DHNQ series was also found for the NTs. In both cases, the averaged values of σ_meta and σ_para were used as the substituent constants