A systematic theoretical study on the stability of a series of dialkyl
peroxides to light and heat
Dialkyl peroxides may decompose under heating and illumination
conditions, and consequently cause an explosion or fire possibility.
However, they can promote diesel-degraded branching reaction, enhance
diesel spontaneous combustion ability, and accelerate the chain reaction
of fuel combustion. In this study, one series of dialkyl peroxides, i.e.
methyl, ethyl, isopropyl, and di-t-butyl peroxide, which have different
numbers of terminal methyl groups, have been modeled. We have
systematically explored their stabilities under heating and illumination
conditions by using CCSD(T), DFT/TDDFT, and variational transition state
theory. We focus on the rate constants of thermal dissociation of
peroxide bonds and absorption spectra because previous experimental and
calculated thermal kinetic parameters are not consistent and the
absorption spectra of these compounds are few. Based on the calculated
data including rate constants and simulated absorption spectra, we find
out that di-t-butyl peroxide is the best candidate among four compounds
considering the stability under both heat and light. The most striking
finding is that the previous assumption that the activation energy of
O-O decomposition equals O-O bond energy may be wrong.