Fischer-Tropsch Synthesis via Carbidic Intermediates

As mentioned in Section II, chain propagation makes use of the carbon building block Cj 11, 0, which, on the basis of the evidence presented, may be written as CH  

It is clear that a value of x = 2 would permit a very simple formulation of the propagation step, attachment of a CH2 unit to a C H2 + 1 radical being the easiest way to create the homologous C H2 + 1 radical with m = n + 1. This is the most obvious way to formulate propagation reaction (6), converting Y into Y +1, as one elementary step. 

Schulz and Achtsnit (77) state that this transfer process cannot be a secondary cracking, as this would lead to a different distribution pattern. Moreover, the absence of cracking under these conditions had been established separately (20). They, therefore, conclude that a metathesis reaction must take place. This is a very interesting suggestion, as the mechanism of olefin metathesis is well established. There seems to be general agreement in the literature on metathesis (65, 69) that the mechanism involves metal carbenes and a metallocyclobutane intermediate, for instance, 

CHRi + CHRj CHRi.CHRj CHRi=CHR2 

CHRi=CHRi + CHR2=CHR2 — 2CHR,=CHR2 (50) 

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