Survival of CO

An answer to the first question was suggested by Lancet and Anders (1970). The principal meteoritic phases stable above 350-400 K (olivine, pyroxene, Fe, FeS) are not effective catalysts for the Fischer-Tropsch reaction, whereas the phases forming below this temperature (hydrated silicates, magnetite) are. P hough metallic iron is often regarded as a catalyst for this synthesis, the catalytically active phase actually is a thin coating of FCjO formed on the surface of the metal (Anderson, 1956)]. Thus CO may have survived metastably until catalysts became available by reactions such as  

This would also explain why the hydrated silicates, carbonates, and organic compounds in Cl s all have the same formation temperature (Table 1). (The deuterium enrichment (Sect. 5.3), if interpreted as an equilibrium fractionation, suggests lower temperatures, but it may actually be due to reactions with D-rich ions). 

More recently, Lewis and Prinn (1980) have systematically examined the reduction kinetics of CO and Nj in the solar nebula. Taking into account gas-phase reactions as well as surface-catalyzed reactions (for the rather inefficient catalysts pr nt above 400 K), they conclude that reaction rates were so slow relative to the rates of radial mixing or nebular evolution that no more than 1 % of the and CO would have been reduced to NHj and CH over the lifetime of the nebula. Methane, the starting material of the Miller-Urey reaction, apparently was only a minor constituent of the solar nebula. 

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We are making the conventional assumption that the nebula cooled isobarically from high temperatures. Actually, the same final state could be reached by isothermal compression or by some intermediate path (Arrhenius and Raub, 1978). In that case, survival of CO would be virtually assured. CO is the stable from of C at low P and T (fig. 10), and although it would have to traverse the graphite-carbyne field in Fig. 10 before reaching the organic compound field, most of it would survice, since reaction rates at low pressures are very slow (Sect. 6.2). 

Gual A, Eugenin J, Alcayaga J, Stensaas LJ, Eyzaguirre C. The chick chorioallantoic membrane promotes survival of co-transplanted rat carotid bodies and nodose ganglia. Brain Res 1991 556 139-144. 

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