Catalytic Alkane Metathesis byTandem Alkane Dehydrogenation–

Olefin Metathesis

Fischer-Tropsch

CH4 + 1/2O2 2H2 + CO

(2n+1)H2 + nCO CnH2n+2 + nH2O

http://en.wikipedia.org/wiki/Fischer-Tropsch_synthesis

Alkane Metathesis

Tandem Alkane Dehydrogenation–Olefin Metathesis

n(Cn) C(2n-2) + ethane

Molecular Redistribution Mechanism by Olefin Intermediates

24.7% 15.9%

Burnett, R. L., Hughes, T. R. J. Catal. 1973, 31, 55

Dehydrogenation catalysts

Schrock-type Metathesis Catalyst

Schrock, R. R. et. al. J. Am. Chem. Soc. 1990, 112, 3875

Representative Examples of the Metathesis of n-hexane

TBEbutylethylene

The Mechanism of Metathesis and Dehydrogenation

Goldman, A. S. et. al. J. Am. Chem. Soc. 1999, 121, 4087

The Reason of Decomposition

2-methyl-2-phenylpropylidene

CH:

2-methyl-2-phenylbutane

2,6-diisopropylaniline

NH2

The Metathesis by Ir-based Catalysts and Re2O7/Al2O3

Conclusions

• The decomposition of the olefin metathesis

catalysts appears to limit conversions.

• The author also expect that more active

dehydrogenation catalysts will give more turnovers before decomposition of the metathesis catalyst.