What is the difference between osmium tetroxide and potassium permanganate in the reaction of alkenes?

1 Answer
Jan 10, 2015

OsO₄ is a catalyst. MnO₄⁻ is a reactant.



  1. The OsO₄ is a catalyst. It reacts with the π electrons of the alkene in a syn addition to form a cyclic osmate ester.

  2. The OH⁻ hydrolyzes the ester. This forms the cis-diol and H₂OsO₄.

  3. The t-BuOOH oxidizes the H₂OsO₄ and regenerates the OsO₄ catalyst:

t-BuOOH + H₂OsO₄ → t-BuOH + OsO₄ + H₂O

#"KMnO"_4"/NaOH/0°C Reaction:"#


As with OsO₄, the reaction goes through a cyclic ester to form a cis diol.

In this case, the MnO₄⁻ is a reactant, not a catalyst, because the MnO₄⁻ is not regenerated.