Kinetics of 1,4-hydrogen migration in the alkyl radical reaction class.

The kinetics of the 1,4-intramolecular hydrogen migration in the alkyl radicals reaction class has been studied using reaction class transition-state theory combined with the linear energy relationship (LER) and barrier height grouping (BHG) approach. The rate constants for the reference reaction of n-C(4)H(9) were obtained by canonical variational transition-state theory (CVT) with the small curvature tunnelling (SCT) correction in the temperature range 300-3000 K with potential-energy surface information computed at the CCSD(T)/cc-pVDZ//BH&HLYP/cc-pVDZ level of theory. Error analyses indicate that RC-TST/LER, where only reaction energy is needed, and RC-TST/BHG, where no other information is needed, can predict rate constants for any reaction in this reaction class with excellent accuracy. Specifically, for this reaction class the RC-TST/LER method has less than 65% systematic errors in the predicted rate constants, while the RC-TST/BHG method has less than 80% error when compared to explicit rate calculations.