RRKM dynamics reaction pathways

As the olefin becomes more complex, more reaction pathways and products become possible and the dynamics are even more complicated. In the case of the reaction of F with various butenes [585, 587], both CH3 and H substitution pathways can occur via long-lived collision complexes. The relative cross sections for the two different channels agree with RRKM predictions in most cases, indicating energy randomisation and some... 

The last issue is the possibility of nonstatistical dynamics. TST and RRKM are statistical theories. If this assumption is true, then both theories can predict reaction rates, leading to what is called statistical dynamics. Of relevance to this chapter is that for statistical dynamics to occur, any intermediates along the reaction pathway must live long enough for energy to be statistically distributed over all of the vibrational modes. If this redistribution cannot occur, then TST and RRKM will fail to predict reaction rates. A principle characteristic of nonstatistical dynamics is a reaction rate much faster than that predicted by statistical theories. 

Apparent non-RRKM behaviour occurs when the molecule is excited non-randomly and there is an initial non-RRKM decomposition before IVR forms a microcanonical ensemble (see section A3.12.2). Reaction pathways, which have non-competitive RRKM rates, may be promoted in this way. Classical trajectory simulations were used in early studies of apparent non-RRKM dynamics [113.114]. 

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