Recombination and dissociation of 2-methyl allyl radicals: Experiment and theory

Abstract

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Thermal dissociation of alkyl nitrites and recombination of alkyl radicals

“…For C1-C4 alkyl nitrites Batt et al[2] determined the O-NO bond energy to be ~41±1.5 kcal/mol. The next weakest bond is C-ONO, ~60 kcal/mol[1,2] and at the low temperatures of this work breaking this bond will be uncompetitive with loss of an NO group.Thus the alkyl nitrites decompose solely by loss of NO. In the nitrites studied here, the O-atom in the oxy radical is attached to a CH 2 group, and elimination of formaldehyde from R-CH 2 O is facile.…”

“…n-Butyl nitrite and iso-butyl nitrite were purchased from Sigma Aldrich and n-propyl nitrite was synthesized following Ref. [1], and the identity and purity was confirmed by infrared spectroscopy, 1 H NMR, and 13 C NMR (Figs. S1-S5, and synthesis method, supplemental material).…”

“…Organic nitrites, RO-NO (R>CH 3 ), are an underexploited, clean, thermal source of radicals that have considerable potential for high temperature chemical kinetic studies. For instance, using thermal decomposition of 3-methyl-but-3-enyl nitrite as a source of an alkenyl radical Tranter et al [1] studied the recombination 2-methylally radicals in the low temperature oxidation regime where the reaction is important to ignition of i-butene. In the current work, the focus is on characterizing alkyl nitrites as sources of alkyl radicals and the subsequent reactions of the radicals.…”

“…The experiments were conducted in a diaphragmless shock tube (DFST) by laser schlieren densitometry (LS) using the same techniques as Ref. [1]. Three alkyl nitrites (C 3 H 7 ONO, n-C 4 H 9 ONO, i-C 4 H 9 ONO) were studied over a broad range of conditions (700<T<1000 K; 60<P<250 Torr).…”

“Third‐body” collision parameters for hydrocarbons, alcohols, and hydroperoxides and an effective internal rotor approach for estimating them

“…Detailed models for the collisional energy transfer function 22,38 have been shown to enable a priori kinetics predictions with errors of just 25%, 22,69 whereas simpler models that incorporate fewer physical details, such as the “single‐exponential‐down” model 17,45 that is often used in energy‐resolved master equation calculations, 70–72 have a priori accuracies of closer to a factor of two 69,73–75 . Again, in an effort to be most directly useful for constructing extensive chemical kinetics tabulations, we restrict attention to models where collision outcomes are controlled by the single parameter α = ⟨Δ E d ⟩, which is the average energy transferred in deactivating collisions.…”