The thermal decomposition of di(trifluoromethyl) peroxide (between 575 and 900 K) and di-tert-butyl peroxide
(between 425 and 650 K) has been investigated by means of a very low pressure pyrolysis method. The
Arrhenius equations for homolytic oxygen−oxygen bond rupture obey log(k
1/s-1) = 15.30−45.0 kcal mol-1/2.303RT for CF3O−OCF3 and log(k
2/s-1) = 15.30−37.4 kcal mol-1/2.303RT for Me3CO−OCMe3. The
oxygen−oxygen bond dissociation enthalpies, BDE(O−O), at 298 K for the peroxides are derived to be 47.5
± 0.5 (CF3O−OCF3) and 38.9 ± 0.5 kcal mol-1 (Me3CO−OCMe3). Various density functional theory
calculations have been utilized to compute the BDEs for XO−H, XO−OH, and XO−OX, with X = H, CF3,
and Me3C. Expansion of the basis set and the application of the restricted open-shell (RO) formalism for the
radical species affords better agreement with experimental values. Using isodesmic reactions, a convergence
is obtained for the BDE(O−H) in trifluoromethanol (CF3O−H) toward 118.8 ± 0.5 kcal mol-1. Reevaluation
of literature thermokinetic data leads to BDE(F−CF2O•) of 27 ± 1, and BDE(CF3O−F) of 48 ± 1 kcal
mol-1.
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