Kinetics of Nonbranched-Chain Addition Processes with Competing
Reactions of 1:1 Adduct Radicals

Michael M. Silaev
Page No. 33-62

Five reaction schemes are suggested for the initiated nonbranched-chain addition of free radicals
to the multiple bonds of the unsaturated compounds. 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 lowreactive
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
nonmonotonic (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 (olefin, 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 nonbranched-chain 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.

Keywords: low-reactive radical, autoinhibitor, competition, energy, hydrogen.