Activation of Alkanes on Metal Surfaces

The effect of delicate adjustments of the catalytic site parameters on the activation modes of hydrocarbons (such as CH4) is further supported by Ichikawa s studies [51] on lamellar compounds. Graphite-K-lamellar entities promote the H -D c.xchangc in methane, but the rate greatly depends on C/K ratio Cj4K gives higher rate (X 2) thanC K at 300°C. Molecular sieves are also active for Ol4- D]0 exchange reactions at 600 C 52]. 

AOIVATION Of ALKANES BY METAL IONS THROUGH 0X11X)REDUCTION PROCESSES 

These types of process are frequently encountered and imply electron transfer from the C H bond to the metal with the formation of radical cations. The Co(IU) acetate oxidation of alkanes probably proceeds, however, through the formation of a radical cobalt complex [S3]. 

The unusual regioseleciivities observed in the chlorination of alkanes by CCU (25) arc explained by the combination of no-bond resonance stabilization and steric control of the coordinated radical formation. 

Tile 4-position is attacked rather than the tertiary carbon atom 2-position as would be expected from radical stabilization steric hindrance favors the 4 osition in relation to the 3-posiiion (electronically stabUized for radical or cation formation). 

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