• Home
• Resources
• CHEM 125A: Freshman Organic Chemistry II
• CHEM 125A: FRESHMAN ORGANIC CHEMISTRY II - Lecture 15 - Professor J. Michael McBride

CHEM 125A: FRESHMAN ORGANIC CHEMISTRY II - Lecture 15 - Professor J. Michael McBride

Metals and Catalysis in Alkene Oxidation, Hydrogenation, Metathesis, and Polymerization

Alkenes may be oxidized to diols by permanganate or by OsO₄ catalysis. Metal catalysts provide orbitals that allow simultaneous formation of two bonds from metal to alkene or H₂. Coupling such oxidative additions to reductive eliminations, provides a low-energy catalytic path for addition of H₂ to an alkene. Such catalytic hydrogenation is often said to involve syn stereochemistry, but the primary literature shows that addition can be anti when allylic rearrangement occurs on the catalyst. Similar oxidative/reductive cycles operate in olefin metathesis and metal-catalyzed polymerization. Careful catalyst design allows control over polymer stereochemistry (tacticity). Polymerizations catalyzed by free-radicals or acids typically lack stereochemical control, but there are ways to control regiochemistry and chain length. Latex, a natural polymer, coagulates to form a rubber ball.