Addition of atomic hydrogen to acetylene. Chain reactions of the vinyl radical

Callear, A. B.; Smith, Geoffrey Benedict

doi:10.1016/0009-2614(84)80426-1

Cited by 20 publications

(10 citation statements)

References 10 publications

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“…For aliphatic fuels, it may be logical to expect the growth of PAHs to start from the first aromatic ring, which in many cases is benzene or phenol radical. Pioneering works on pyrolysis/oxidation of acetylene (C2H2) [141][142][143], C2H2/H2 mixture [144], methyl chloride (CH3Cl) [145], and rich premixed flames of C2H2 [146], ethylene (C2H4) [147], and 1,3-butadiene (1,3-C4H6) [148] suggest that the following reactions are important for benzene (A1) formation from small aliphatics:…”

Section: Formation Of First Aromatic Ringmentioning

confidence: 99%

Soot formation in laminar counterflow flames

Wang

Chung

2019

Progress in Energy and Combustion Science

336

116

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Many practical soot-emitting combustion systems such as diesel and jet engines rely on diffusion flames for efficient and reliable operation. Efforts to mitigate soot emissions from these systems are dependent on fundamental understanding of the physicochemical pathways leading from fuel to soot in laminar diffusion flames. Existing diffusion flame−based soot studies focused primarily on overventilated coflow flame where the fuel gas (or vapor) issues from a cylindrical tube into a co-flowing oxidizer, and counterflow flame, where a reacting zone is established between two opposing streams of fuel and oxidizer. As a canonical diffusion flame configuration, laminar counterflow diffusion flames have been widely used as a highly controllable environment for soot research, enabling significant progress in the understanding of soot formation for several decades. In view of the possibility of fuel/oxidizer premixing in practical systems, counterflow partially premixed flames have also been studied. In the present work we intend to provide a comprehensive review of the researches on various aspects of soot formation utilizing counterflow flames. Major processes of soot formation (formation of gas phase soot precursors, soot inception and surface reactions, as well as particle-particle interactions) are examined first, with focus on the most recent (post-2010) research progress. Experimental techniques and associated challenges for the measurement of soot-related properties (some knowledge of which is helpful for full appreciation of the experimental data to be reviewed) are then introduced. This is followed by a detailed description of soot evolution in counterflow flames, which is complemented by a discussion on the similarity and differences of the sooting structures between counterflow and coflow diffusion flames. Parametric studies of the effects of fuel molecular structure, fuel additive, partial-premixing, pressure, temperature, stoichiometric mixture fraction, and residence time on soot formation in counterflow flames will then be addressed in detail. This review concludes with a summary of the knowledge and challenges gathered and demonstrated through decades of research, and an outlook on opportunities for future counterflow flame−based soot research towards a more complete understanding of soot formation and the development of novel techniques for soot mitigation in practical combustion devices.

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Section: Formation Of First Aromatic Ringmentioning

confidence: 99%

Soot formation in laminar counterflow flames

Wang

Chung

2019

Progress in Energy and Combustion Science

336

116

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“…Several C 4 H 5 radical isomers are important intermediates in the pyrolysis − and photochemistry − of unsaturated hydrocarbons, and are candidates for detection in the interstellar medium . Various C 4 H 5 isomers have been under investigation since 1967, when Martin and Sanders measured the kinetics of perester decomposition to radical products and Benson and Haugen included the 1,3-butadienyl radicals in their kinetic model of radical-mediated carbon chain formation .…”

Section: Introductionmentioning

confidence: 99%

“…Various C 4 H 5 isomers have been under investigation since 1967, when Martin and Sanders measured the kinetics of perester decomposition to radical products and Benson and Haugen included the 1,3-butadienyl radicals in their kinetic model of radical-mediated carbon chain formation . Subsequent kinetics studies have probed the role of these radicals in the photolysis of 2-butyne, the thermal decomposition of pentyne and pentadiene, , the pyrolysis of 1-butyne 3 and 1,2-butadiene, and the radical-mediated chain formation leading to aromatic compounds. − ,,,, Several of these studies have succeeded in predicting formation enthalpies for the more stable C 4 H 5 isomers. There are also many ESR measurements of the magnetic and hyperfine properties of selected C 4 H 5 isomers. − An elegant crossed-beam study by Kaiser and co-workers has recently probed the mechanism for formation of several of these structures from the reaction of propene and atomic carbon …”

Section: Introductionmentioning

confidence: 99%

Ab Initio Study of the Most Stable C₄H₅ Isomers

Parker

Cooksy

1999

J. Phys. Chem. A

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Ab initio calculations have been carried out on the lowest energy isomers of C4H5 to predict spectroscopic properties and relative stabilities. Geometry optimizations were carried out on stationary point conformations of seven configurational isomers at UHF, B3LYP, MP2, CISD, QCISD, MCSCF(7,7), and MCSCF(9,9) levels of theory. Single-point energies were evaluated at the MP4, CCSD(T), MCSCF(11,11), and multireference CISD levels. Disparities as large as 70 kJ mol-1 are found between relative energies predicted by single- and multireference methods for the same isomer. Comparison to experimental values suggests that the multireference methods inadequately model the relative correlation energy. Zero-point corrected relative energies (in kJ mol-1) obtained at the QCISD level with a 6-311G(d,p) basis set are the following: 2-butyn-1-yl (0); 1-butyn-3-yl (10); 1,2-butadien-4-yl (13); cyclobuten-3-yl (17); 1,3-butadien-2-yl (50); 1,3-butadien-1-yl (59); and 1-butyn-4-yl (64). Relative energies calculated by multireference methods are higher, and decrease slowly as the active space size increases. Relative energies and hyperfine constants obtained at the QCISD level are in agreement with available experimental data and empirical estimates. Some of these isomers are candidates for relocalization, a phenomenon that results in predicted multiple minima and unusually flat vibrational potential energy surfaces for the isoelectronic C3H3O isomers. Of the present series of molecules, only 2-butyn-1-yl exhibits an especially flat bending potential along the appropriate isomerization coordinate. Predicted vibrational transition frequencies and intensities, dipole moment components, Fermi contact hyperfine constants, and conformational potential energy curves are presented.

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“…The butadienyl radicals are possible intermediates in the pyrolysis of hydrocarbons and the formation of benzene in flames. − The radical isomers obtained by abstraction of a hydrogen atom from 1,3-butadiene are 1,3-butadien-1-yl and 1,3-butadien-2-yl, assuming that the geometry of the parent molecule is preserved. Both radicals have cis and trans configurational isomers due to the possibility of internal rotation about the CC single bond.…”

Section: Introductionmentioning

confidence: 99%

Ab Initio Study of the 1,3-butadienyl Radical Isomers

Parker

Cooksy

1998

J. Phys. Chem. A

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Ab initio calculations at the B3LYP, QCISD, and MCSCF levels of theory and using the 6-311G(d,p) basis set were carried out on the ground state of the 1,3-butadiene derived radicals. The 1,3-butadien-1-yl and 1,3-butadien-2-yl radicals are obtained from 1,3-butadiene by abstraction of a hydrogen atom from a primary and secondary carbon, respectively. The 1,2-butadien-4-yl radical was also studied to examine the possibility of the relocalization of the unpaired electron from 1,3-butadien-2-yl. 1,2-Butadien-4-yl was consistently found to be the most stable isomer. The MCSCF relative energies are 29 kJ mol-1 for 1,3-butadien-2-yl and 35 kJ mol-1 for the most stable of the 1,3-butadien-1-yl configurational isomers. The 1,3-butadien-2-yl structure is found to be a local minimum in MCSCF calculations, but with an isomerization barrier of less than 1 kJ mol-1, and deforms to the 1,2-butadien-4-yl isomer at all other levels of theory used. The energy of the most stable 1,3-butadien-1-yl isomer relative to 1,3-butadien-2-yl ranges from 6 to 18 kJ mol-1 across all levels of theory used, substantially lower than previous predictions by ab initio and semiempirical means. Optimized geometries, relative energies, permanent dipole moments, Fermi contact terms and harmonic vibrational frequencies are reported.

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Addition of atomic hydrogen to acetylene. Chain reactions of the vinyl radical

Cited by 20 publications

References 10 publications

Soot formation in laminar counterflow flames

Soot formation in laminar counterflow flames

Ab Initio Study of the Most Stable C₄H₅ Isomers

Ab Initio Study of the 1,3-butadienyl Radical Isomers

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Addition of atomic hydrogen to acetylene. Chain reactions of the vinyl radical

Cited by 20 publications

References 10 publications

Soot formation in laminar counterflow flames

Soot formation in laminar counterflow flames

Ab Initio Study of the Most Stable C4H5 Isomers

Ab Initio Study of the 1,3-butadienyl Radical Isomers

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Product

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Ab Initio Study of the Most Stable C₄H₅ Isomers