Hydrovinylation


In organic chemistry, hydrovinylation is the formal insertion of an alkene into the C-H bond of ethylene. The more general reaction, hydroalkenylation is the formal insertion of an alkene into the C-H bond of any terminal alkene. The reaction is catalyzed by metal complexes. A representative reaction is the conversion of styrene and ethylene to 3-phenybutene:

Ethylene dimerization

The dimerization of ethylene gives 1-butene is another example of a hydrovinylation. In the Dimersol and Alphabutol Processes, alkenes are dimerized for the production of gasoline and for comonomers such as 1-butene. These processes operate at several refineries across the world at the scales of about 400,000 tons/year. 1-Butene is amenable to isomerization to 2-butenes, which is used in Olefin conversion technology to give propylene.

Hydroarylation

Hydroarylation is again a special case of hydrovinylation. Hydroarylation has been demonstrated for alkyne and alkene substrates. An early example was provided by the Murai reaction, which involves the insertion of alkenes into a C-H bond of acetophenone. The keto group directs the regiochemistry, stabilizing an aryl intermediate.
When catalyzed by palladium carboxylates, a key step is electrophilic aromatic substitution to give a Pd aryl intermediate.

In organic synthesis

As first reported by Alderson, Jenner, and Lindsey hydrovinylation uses rhodium- and ruthenium-based catalysts. Catalysts based on iron, cobalt, nickel, and palladium have also been demonstrated. The addition can be done highly regio- and stereoselectively, the choices of metal centers, ligands, substrates and counterions often play very important role. N-heterocyclic carbene complexes of Ni allow the selective preparations of functionalized geminal olefins or 1,1-disubstituted alkenes.