SEPARATION OF CLOSELY BOILING ISOMERS AND IDENTICALLY BOILING ISOTOPOMERS VIA ELECTRON-TRANSFER-ASSISTED EXTRACTION

Mixtures of isotopomers with identical molecular weights (ethyl-d(5)-b enzene + ethylbenzene-d(5) and tert-butyl-d(9)-biphenyl + tert-butylbi phenyl-d(9)) have been partially resolved by making use of their diffe ring solution electron affinities. EPR analysis of the anion radicals resulting from the partial potassium reduction of mixtures of the isot opomers (R and R, respectively) in tetrahydrofuran show that the equi librium constant for the reaction R.-,M+ + R = R + *R.-,M+ deviates f rom unity. These EPR results predict that a separation of anion radica l from neutral molecule would effect a separation of the isotopomers, Removal of the solvent leaves a solid mixture of neutral and potassium anion radical salt forms of the isotopomers. Subsequent dissolution o f the neutral materials from the anion radical salts yields a mixture that is enriched in the ring-deuterated isotopomer, and reoxidation of the anion radical with iodine yields a mixture that is enriched in th e ring-protiated isotopomer. Analogous experiments were also used to s eparate closely bailing geometric isomers.