Intermediate oxygen range

Adsorbed water was observed to have a large effect on the F spin-lattice relaxation time for fluorine-doped aluminas in the dilute and intermediate concentration range of fluorine (0.3-8 wt. % F). An increase in Ti by a factor of 2 to 3 was observed in these samples when adsorbed water was removed from the solid by heating between 200-300°. The effect was completely reversible addition of oxygen-free water back to the solid resulted in recovery of the original (shorter) relaxation time. This effect was observed by the measurement of the in phase and ir/2 out of phase components of the dispersion derivative at resonance dx /6Ho at high rf power, from which effective values of Ti may be calculated 46). Values of Ti were also obtained by saturation of the resonance absorption derivative. 

As stated above. It has been established that carboxylate Ions are the true Initiators in B lactone polymerization. In an early study. Hall ( ) stated that In Intermediate pH ranges anions or water Itself attack the CH2 group with alkyl-oxygen cleavage by SN2 reaction that proceeds most rapidly In anhydrous acetonitrile or tetrahydrofuran. From heats of combustion he determined the heat of polymerization of plvalolactone AH j. to be -20.1 kcal mol l. 

In intermediate concentration ranges, the free radicals, as well as oxygen, react with the iron(III) chelate, [Fe(OH)(RS)s] 2, to form iron(II) and the disulfide 131). 

In accordance with the abimdance of certain products, the intermediate-temperature range can be in turn divided into three subranges those of preferential formation of oxygenates (300—600 °C), oxidative coupling of methane (OCM) with predominant formation of C2 hydrocarbons (600—900 °C), and preferential formation of syngas (>900 °C) (Fig. 12.1). This division corresponds to obvious changes in the kinetic mechanism with the temperature of the process. 

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