Acyclic alkanes from mixtures

In the presence of an acyclic alkane, 3 catalyzes at moderate temperature (25-200 °C) the metathesis reaction, leading to the formation of heavier and lower homolog alkanes by simultaneous breaking and formation of C-H and C-C bonds. For example, propane is transformed, even at 25 °C into a quasi-equimolar mixture of ethane and butanes (n- and iso-mixture) as well as methane and pentanes, in lower quantities. Lower and heavier homologs are also obtained starting from... 

Gas Chromatography. Whereas N.M.R. effectively senses the f mctional groups present in a mixture, differences between retention times enable G.C. to identify individual members (provided they are moderately volatile) of a homologous series such as the n-alkanes. Positive identification requires calibration by co-injection with authentic samples (here n-alkanes) or coupling of M.S. with, preferably, a capillary G.C. column. Although G.C. stick diagrams of n-alkane distributions have been used for comparing extracts from fossil fuels, we advocate acyclic-isoprenoid-hydrocarbon distributions, and particularly the pristane/phytane ratio, as more reliable indicators of fossil fuel maturation 6). 

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