OsO4-catalyzed dihydroxylations Reoxidants are commonly used in reactions catalyzed by
osmium tetroxide, which is a primary oxidant converting alkenes to
glycols. The spent catalyst is an osmium(VI) complex, which reacts with a reoxidant to regenerate Os(VIII). Typical reoxidants for this application include
pyridine-N-oxide, ferricyanide/water, and
N-methylmorpholine N-oxide.
Vanadium(III)-based alkene polymerizations As catalysts for the polymerization of dienes, vanadium complexes are activated with alkylaluminium chlorides, e.g.
diethylaluminium chloride. The organoaluminium reagent installs alkyl groups on the V(III) precatalyst. During catalysis or during
catalyst activation, some vanadium(III) is reduced to inactive vanadium(II) derivatives. To correct for this reduction, reoxidants such as methyl trichloroacetate are added. The alkyl chloride functions as a source of a chlorine radical, which adds to the inactive V(II) species. In some cases, the reoxidants are called
rejuvenators. :
oxidation: RCH2OH + 2 TEMPO → RCHO + 2 TEMPO-H :
reoxidation: 2 TEMPO-H + I2 → 2 TEMPO + 2 HI ==References==