Thermochemical and kinetic analysis of the allyl radical with O2 reaction system
Document Type
Article
Publication Date
1-1-2005
Abstract
Thermochemical properties and kinetics for the allyl radical (CH2=CHCH2) + O2 reaction system are analyzed to evaluate reaction paths and kinetics in thermal oxidation. (ΔHf 2980) are determined using isodesmic reaction analysis at the CBSQ//B3LYP/6-31G(d,p) composite and at density functional levels. Entropies (S2980) and heat capacities (Cp0 (T)) are determined using structures and vibrational frequencies obtained at the B3LYP/6-31G(d,p) level of theory. Internal rotor contributions are included in S and Cp(T) values. The allyl radical adds to O2 to form an energized peroxy adduct [CH2=CHCH2OO]∗ with a shallow well, only 20 kcal/mol barrier to dissociation. Reaction channels of the peroxy adduct [CH2@CHCH2OO]∗ include reverse reaction, stabilization, isomerizations via hydrogen shift with subsequent b-scission or R O-OH bond cleavage. The peroxy adduct can also cyclize to four- or five-member cyclic peroxide-alkyl radicals, C H2YCCOO and YCC COO (Y = cyclic). All pathways in this allyl plus O2 system are found to involve barriers that are higher than reverse reaction. The most accessible product (only 5 kcal/mol above reverse reaction) is the cyclization to a five-member ring, that reacts further with O2, resulting in carbonyl and chain propagation products. Other important products are: allene + HO2 via molecular elimination and C H=CHCH2OOH (via hydrogen shift), which undergoes b-scission leading to C2H2 + CH2O + OH above 600 K. Rate constants are estimated as a function of pressure and temperature using quantum Rice-Ramsperger-Kassel analysis for κ(E) and master equation for falloff.
Identifier
84964285921 (Scopus)
Publication Title
Proceedings of the Combustion Institute
External Full Text Location
https://doi.org/10.1016/j.proci.2004.08.092
ISSN
15407489
First Page
1015
Last Page
1022
Issue
1
Volume
30
Recommended Citation
Lee, Jongwoo and Bozzelli, Joseph W., "Thermochemical and kinetic analysis of the allyl radical with O2 reaction system" (2005). Faculty Publications. 19930.
https://digitalcommons.njit.edu/fac_pubs/19930
