Polarographic Studies on Substituted 2,2′-Bipyridyl N-Oxides

TLDR: In this article, the polarographic behavior of 4-methoxy-2,2′-bipyridyl 1-oxide has been investigated in 20% dioxane-water solution.

Abstract: The polarographic behavior of 4-methoxy-2,2′-bipyridyl 1-oxide has been investigated in 20% dioxane-water solution. Two well defined reduction waves appear in the pH range 0.76–8.8, a third wave in pH 9.3–10.4, but only one wave in more alkaline solutions. The variation of E1⁄2 with pH followed the relations (E1⁄2)1=−0.37–0.10 pH and (E1⁄2)2=0.84−0.065 pH for waves 1 and 2, respectively. The diffusion current constant for the second wave decrease with increasing pH whereas for the first wave it remains constant upto pH 7.0 and decreases afterwards. Variation of diffusion current with temperature and reservoir height indicates the diffusion controlled nature. Wave 1 is produced by the 2 electron reduction of protonated N-oxide to 4-methoxy-2, 2′-bipyridyl. This intermediate is further reduced, at more negative potentials, to 1,4′-dihydro-4-methoxy-2,2′-bipyridyl by consuming two more electrons and two hydrogen ions simultaneously. The third wave is presumably due to catalytic hydrogen evolution.