Determination of standard potentials and electron-transfer rates for halobiphenyls from electrocatalytic data

Electron-transfer properties of halogenated biphenyl (PCB's and PBB's) are important in their synthetic, environmental, and biological transformations, many of which involve radical pathways. The electrocatalytic method was used to obtain standard formal potentials (E/sup 0/') and homogeneous electron transfer rate constants (k/sub ss/) for five halobiphenyls of representative structures. A nonlinear regression method was developed to obtain the best fit of theory to the log k/sub 1/ vs. E/sub PQ//sup 0/ data and yielded optimized values of parameters. Precisions of 2-7 mV in E/sup 0/' and 0.1-0.4 in log k/sub ss/ were improved over those obtained graphically. A correlation was observed between E/sup 0/' of the halobiphenyls and biological activity. 25 references, 1 figure, 8 tables.