Phenoxy Radical (C₆H₅O) Formation under Single Collision Conditions from Reaction of the Phenyl Radical (C₆H₅, X²A₁) with Molecular Oxygen (O₂, X³Σ_g^–): The Final Chapter?

Abstract

The combustion relevant elementary reaction of photolytically generated phenyl radicals (C(6)H(5), X(2)A(1)) with molecular oxygen to form the phenoxy radical (C(6)H(5)O) plus a ground state oxygen atom was investigated under single collision conditions at a collision energy of 21.2 ± 0.9 kJ mol(-1). The reaction was found to proceed indirectly via the involvement of a long-lived phenylperoxy radical (C(6)H(5)O(2)) intermediate that decomposed via a rather loose exit transition state. In comparison with crossed beams data obtained previously at elevated collision energies, we suggest that, as the collision energy rises from 21 to 107 kJ mol(-1), the lifetime of the C(6)H(5)O(2) reaction intermediate decreases, that is, a classical behavior within the osculating complex model.

Rate coefficients and product branching ratios for the oxidation of phenyl and naphthyl radicals: A theoretical RRKM-ME study

“…A detailed theoretical analysis of the mechanism and kinetics of their reactions with O 2 is sought to better understand how larger PAH radicals are oxidized in flames. The mechanism and kinetics of the C 6 H 5 +O 2 reaction has received considerable attention by the combustion community in the last two decades [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17].…”

“…Additionally, the minor reaction channels producing o-and p-benzoquinone, o/p-C 6 H 4 O 2 , plus H atoms were also suggested [7]. However, the only products observed in the recent crossed molecular beam experiments at collision energies of 5-26 kcal mol -1 [15][16][17], which correspond to high combustion temperatures and beyond, were C 6 H 5 O+O.…”

Revisiting the photodissociation dynamics of the phenyl radical

“…These studies concluded that o-benzyne was the most likely C 6 as well as several further experimental and computational studies by Kaiser and co-workers. 12,[47][48][49] In work from our laboratory, Negru et al 50 investigated the photodissociation of the phenyl radical at 248 and 193 nm via photofragment translational spectroscopy. The radicals were produced by flash pyrolysis 51 of nitrosobenzene (C 6 H 5 NO).…”

Theoretical study of the triplet state aryl cations recombination: A possible route to unusually stable doubly charged biphenyl cations

“…The reactions of phenyl radicals are gaining interest among the study of the carbonaceous soot particles formation mechanism and their precursors, such as polycyclic aromatic hydrocarbons due to their importance in combustion, atmospheric, interstellar, and graphene chemistry . The diazonium salt‐derived phenyl (aryl) radicals known as effective grafting agents for metal and organic surfaces provide an additional reason for the extensive study of these species .…”