Modern theories of chemical reactions in condensed phases

Thermolysis of organic peroxides in solution

“…According to X-ray diffraction data, 34 the hydroperoxide homoassociates R7O (1) 7O (2) 7H can have different structures depending on the structure of the radical R. Thus tert-butyl hydroperoxide molecules form a hydrogen bond including the O (1) atom, whereas 1,1-diphenyl hydroperoxides form a hydrogen bond including the O (2) atom. Because of steric hindrance, triphenylmethyl hydroperoxide forms a hydrogen bond with the p-electrons of the benzene ring of the second hydroperoxide molecule rather than with oxygen atoms.…”

“…where k (1) and k (2) are complex combinations of kinetic constants and acetone concentration. The first component of Eqn (23) reflects the consumption of compound 7b in the reaction with the acetonyl radical, while the second one describes the contribution of reaction (13) to the total rate of DMDO decomposition.…”

“…They are widely used for initiating radical (including chain) processes and crosslinking of polymers. 1,2 The low thermal stability of peroxides due to the presence of a weak O7O bond and the strong dependence of the decomposition time on their structures allow their wide use as initiators in a broad range of temperatures, from * 40 to * 200 8C. Redox systems of the type `hydroperoxide ± metal ion' and `diacyl peroxide ± amine' enable initiation even at 0 8C.…”

“…Intermolecular contacts and reactions occurring in the solvent cage affect essentially the kinetics, mechanism and, as a consequence, composition of reaction products. 1,2 Thermal decomposition of organic peroxides has previously been considered in several monographs. 5 ± 10 The effect of pressure on the kinetics and mechanisms of thermolysis (including DV T ) depends on the mode of the interaction of the reactants with the solvent, the viscosity of the solvent and the processes occurring in the solvent cage.…”

Theoretical Study of the Intramolecular Localization and Migration of a Triplet Exciton in the N,N′-Di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (α-NPD) Molecule

“…This process takes place on a single potential energy surface. Therefore, the corresponding rate constant can be calculated by the Arrhenius equation k = k 0 e – E a / k B T with the pre-exponential factor k 0 taken to be equal to the frequency of the reorganization mode − and the activation energy E a taken at the barrier top on the T 1 surface. The barrier height can be found from the energy profile, and the frequency of the reorganization mode used as a pre-exponential factor can be found after considering the contributions of normal modes to the reorganization energy (the soft mode with the largest contribution is taken as the reorganization mode).…”