Effect of Charge Distribution upon Condensed-Phase Electron Transfer between Isotopic Isomers

Article abstract of DOI:10.1021/jo00300a027

EPR analysis of the anion radicals resulting from the partial potassium reduction of mixtures of perdeuteriated and perprotiated polyaromatics (*R and R, respectively) in tetrahydrofuran shows that the equilibrium constant for the reaction R-radicalanion,M+ + *R -> <- R + *R-radicalanion,M+ is less than unity but that it is closer to unity for systems with large amounts of charge density on the ring juncture carbons.These EPR results predict that a separation of anion radical from neutral molecule would effect an isotopic separation.Removal of the THF leaves a solid mixture of neutral polyaromatic and the potassium anion-radical salt.Subsequent dissolution or sublimation of the neutral polyaromatics from the anion radical yields a mixture that is enriched in the heavy isotopic isomer, and reoxidation of the anion radical with iodine yields a mixture that is depleted in the heavy isotopic isomer.The room-temperature equilibrium constants obtained from these physical separations are not as large as those measured in solution due to lattice effects in the solid state.