The aim of this study was the conclusion of simple kinetic equations to
describe ab initio initiated Nonbranched-chain processes
of the saturated free-radical addition to the double bonds of
unsaturated molecules in the binary reaction systems of saturated
and unsaturated components. In the processes of this kind the formation
rate of the molecular addition products (1:1 adducts) as
a function of concentration of the unsaturated component has a maximum.
Five reaction schemes are suggested for this addition
processes. The proposed schemes include the reaction competing with
chain propagation reactions through a reactive free radical.
The chain evolution stage in these schemes involves three or four types
of free radicals. One of them is relatively low-reactive
and inhibits the chain process by shortening of the kinetic chain
length. Based on the suggested schemes, nine rate equations
(containing one to three parameters to be determined directly) are
deduced using quasi-steady-state treatment. These equations
provide good fits for the no monotonic (peaking) dependences of the
formation rates of the molecular products (1:1 adducts) on the
concentration of the unsaturated component in binary systems consisting
of a saturated component (hydrocarbon, alcohol, etc.) and
an unsaturated component (alkene, allyl alcohol, formaldehyde, or
dioxygen). The unsaturated compound in these systems is both a
reactant and an autoinhibitor generating low-reactive free radicals. A
similar kinetic description is applicable to the Nonbranchedchain
process of the free-radical hydrogen oxidation, in which the oxygen with
the increase of its concentration begins to act as an
oxidation autoingibitor (or an antioxidant). The energetics of the key
radical-molecule reactions is considered.
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