Direct studies of peroxy radical isomerizations

The variation in A+ with [O2] arises from the complex interplay between reactions (60-62). At high [O2], decomposition of the alkyl radical cannot compete with the addition of oxygen and peroxy radical formation is fast and irreversible (/c6i[02] 5 k-(,i). The concentration of oxygen required to achieve this condition will increase with temperature as both k o and A 6i depend sensitively on temperature. Under these conditions k(,2 is the 

Baldwin et al. qualified the absolute accuracy of their results by noting that the calculated values, as we have seen, are dependent on values of alkyl radical decomposition rates and the alkyl/alkylperoxy radical equilibrium constant. The work of Hughes et al. [122] now means that the data of Baldwin et al. can be appropriately scaled to give the results shown in Table 2.10. 

Further evidence for the validity of the approach adopted by Baldwin et al. and Hughes et al. comes from a comparison of activation energies for the formation of the same sized rings but formed by either primary, secondary or tertiary hydrogen abstractions. According to the two component hypothesis advanced above the ring strain component should be identical in both cases and this is borne out by the following observations  

The data obtained by Hughes et al. gives an indication of the level of detailed knowledge that can be gained from direct studies of appropriate chemical systems and also the complementary nature of direct and indirect studies. However, even in these ideal reactions the chemistry can rapidly become increasingly complex and this may represent the limits of direct studies. 

8 THEORETICAL AND DYNAMICAL STUDIES OF THE HYDROGEN/OXYGEN SYSTEM 

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