Electron-Transfer Reactions of Organosulfur Cation Radicals

The thianthrene cation radical (Th ˙+ ) undergoes electron transfer in reactions with a number of azoalkanes. The oxidized azoalkanes then enter primarily into carbocation reaction pathways rather than the free radical pathways with which they are commonly associated. Examples are given with 1,1′-azoadamantane, phenylazotriphenylmethane, azotoluene, and azo-tertiary-butane. Reactions of Th ˙+ with Grignard agents also result, to varying extents, in electron transfer from the Grignard to Th ˙+ . Here again carbocation chemistry is seen but particularly with solvent tetrahydrofuran, which polymerizes. The Grignard group may end up primarily as alkane (e.g., with t-butyl) or may also be trapped by Th ˙+ in the form of a 5-alkylthianthre-niumyl ion (e.g. with butyl). Possible mechanisms of reactions are discussed