Methane substituted

The Joback method works quite well in methane substitutes for boiling points, except for the —H, the —F and —NO2 molecules see figure 5.14. However, the melting points are much less satisfactory, as they depend not only on the properties of the groups added, but also on the architecture and the shapes of the molecules. 

Less obvious than the reactivity discussed above is the chemical instability brought about by hyperconjugation or conjugation of incompatible groups. Methanes substituted with both amino and acyl groups, for example a-amino ketones, tend to form radicals readily (Scheme 5.69), and can undergo facile thermal rearrangements (Scheme 3.11). 

Ttie second large-scale use of methane is its halogenation [I], where chlorine and fluorine are the most important halogens for methane substitution. Chloro-methanes aie formed by thermal chlorination or catalyzed uxychlorination of methane. Monochlorination is controlled by using a ten-fold excess of methane. 

Ethane represents one of the less investigated light hydrocarbons for total oxidation, at least comparatively to methane. Substituted Lai eSr tFe03 perovskites [36] and substituted halo- Lai eSr tFe03 5Xo. (X = F, Cl) perovskites [37] were reported to convert ethane at temperatures higher than 400 °C with a maximum in selectivity in CO2 of 60%. For both perovskites, ethene was the only by-product. Also, the substitution of La by K in Lai eK eMn03 perovskites decreased the activity for ethane combustion and allowed the formation of ethylene [38,39]. These studies also point out that the bulkier cation in the A position perovskite structure plays a role in determining the catalytic performance. 

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