H Atom Branching Ratios from the Reactions of CH with C2H2, C2H4, C2H6, and neo-C5H12 at Room Temperature and 25 Torr

McKee, Kenneth W.; Blitz, Mark A.; Hughes, Kevin J.; Pilling, Michael J.; Qian, Huanyan; Taylor, Ashby B.; Seakins, Paul W.

doi:10.1021/jp021613w

Cited by 48 publications

(70 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…19 Within the photon energy range employed in this study these three C 3 H 4 isomers are likely to be the only contributors to the ion signal at m/z=40. Figure 4 The photoionization cross section of allene and methylacetylene have been measured by Cool at al.…”

Section: Methylidyne Reaction With Ethylenementioning

confidence: 88%

“…The experimental branching ratios are displayed in Table 3 and compared to predicted branching ratios based on RRKM calculations using calculated C 3 H 5 potential energy surfaces. 19 Figure 4 These results suggest that the reaction pathway leading to the formation of allene proceeds mainly via Helimination when methylacetylene formation proceeds mainly via D-elimination.…”

Section: Methylidyne Reaction With Ethylenementioning

confidence: 89%

“…[17][18][19]43,64 Stabilization of C 3 H 3 intermediates are usually not considered as important exit channels due to the high exothermicity for the reaction intermediate formation. For the entrance channel, insertion of the CH radical into the C−H bond is considered to be unfavorable due to the large change of entropy compared to cycloaddition onto the π-electron system.…”

Section: Formation Mechanism Of C 3 H 2 Isomers By Reaction Of the Chmentioning

confidence: 99%

“…McKee et al 19 discussed the mechanism of this reaction and concluded that the fate of any cyclopropyl radical is likely to be conversion into the stable allyl radical. Direct elimination of the H atom on the central carbon from the allyl radical leads to the formation of allene.…”

Section: Formation Mechanism Of C 3 H 4 Isomers By Reaction Of the Chmentioning

confidence: 99%

“…The corresponding mechanism for reaction of the CD radical with ethylene is depicted in Figure 7. McKee et al 19 used the potential energy surfaces calculated by Davis et al 75 and Deyerl et al 76 to perform statistical calculations of the CH + ethylene product branching ratios. Table 2 compares the calculated values 19 to the experimental results obtained in the current study.…”

Section: Formation Mechanism Of C 3 H 4 Isomers By Reaction Of the Chmentioning

confidence: 99%

See 4 more Smart Citations

Cyclic Versus Linear Isomers Produced by Reaction of the Methylidyne Radical (CH) with Small Unsaturated Hydrocarbons

et al. 2009

View full text Add to dashboard Cite

The reactions of the methylidyne radical (CH) with ethylene, acetylene, allene, and methylacetylene are studied at room temperature using tunable vacuum ultraviolet (VUV) photoionization and time-resolved mass spectrometry. The CH radicals are prepared by 248 nm multiphoton photolysis of CHBr 3 at 298 K and react with the selected hydrocarbon in a helium gas flow. Analysis of photoionization efficiency versus VUV photon wavelength permits isomer-specific detection of the reaction products and allows estimation of the reaction product branching ratios. The reactions proceed by either CH insertion or addition followed by H atom elimination from the intermediate adduct. In the CH + C 2 H 4 reaction the C 3 H 5 intermediate decays by H atom loss to yield 70(±8)% allene, 30(±8)% methylacetylene and less than 10% cyclopropene, in agreement with previous RRKM results. In the CH + acetylene reaction, detection of mainly the cyclic C 3 H 2 isomer is contrary to a previous RRKM calculation that predicted linear triplet propargylene to be 90% of the total H-atom co-products. High-level CBS-APNO quantum calculations and RRKM calculation for the CH + C 2 H 2 reaction presented in this manuscript predict a higher contribution of the cyclic C 3 H 2 (27.0%) versus triplet propargylene (63.5%) than these earlier predictions.Extensive calculations on the C 3 H 3 and C 3 H 2 D system combined with experimental isotope ratios for the CD + C 2 H 2 reaction indicate that H-atom assisted isomerization in the present experiments is responsible for the discrepancy between the RRKM calculations and the experimental results. Cyclic isomers are also found to represent 30(±6)% of the detected products in the case of CH + methylacetylene, together with 33(±6)% 1,2,3-butatriene and 37(±6)% vinylacetylene. The CH + allene reaction gives 23(±5)% 1,2,3-butatriene and 77(±5)% vinylacetylene, whereas cyclic isomers are produced below the detection limit in this reaction. The reaction exit channels deduced by comparing the product distributions for the aforementioned reactions are discussed in detail.3

show abstract

Section: Methylidyne Reaction With Ethylenementioning

confidence: 88%

Section: Methylidyne Reaction With Ethylenementioning

confidence: 89%

Section: Formation Mechanism Of C 3 H 2 Isomers By Reaction Of the Chmentioning

confidence: 99%

Section: Formation Mechanism Of C 3 H 4 Isomers By Reaction Of the Chmentioning

confidence: 99%

Section: Formation Mechanism Of C 3 H 4 Isomers By Reaction Of the Chmentioning

confidence: 99%

See 3 more Smart Citations

Cyclic Versus Linear Isomers Produced by Reaction of the Methylidyne Radical (CH) with Small Unsaturated Hydrocarbons

et al. 2009

View full text Add to dashboard Cite

show abstract

Theoretical mechanistic study of the reaction of the methylidyne radical with methylacetylene

et al. 2011

View full text Add to dashboard Cite

A detailed doublet potential energy surface for the reaction of CH with CH(3)CCH is investigated at the B3LYP/6-311G(d,p) and G3B3 (single-point) levels. Various possible reaction pathways are probed. It is shown that the reaction is initiated by the addition of CH to the terminal C atom of CH(3)CCH, forming CH(3)CCHCH 1 (1a,1b). Starting from 1 (1a,1b), the most feasible pathway is the ring closure of 1a to CH(3)-cCCHCH 2 followed by dissociation to P ( 3 )(CH(3)-cCCCH+H), or a 2,3 H shift in 1a to form CH(3)CHCCH 3 followed by C-H bond cleavage to form P ( 5 )(CH(2)CHCCH+H), or a 1,2 H-shift in 1 (1a, 1b) to form CH(3)CCCH(2) 4 followed by C-H bond fission to form P ( 6 )(CH(2)CCCH(2)+H). Much less competitively, 1 (1a,1b) can undergo 3,4 H shift to form CH(2)CHCHCH 5. Subsequently, 5 can undergo either C-H bond cleavage to form P ( 5 ) (CH(2)CHCCH+H) or C-C bond cleavage to generate P ( 7 ) (C(2)H(2)+C(2)H(3)). Our calculated results may represent the first mechanistic study of the CH + CH(3)CCH reaction, and may thus lead to a deeper understanding of the title reaction.

show abstract

F/Cl + C2H2 reactions: Are the addition and hydrogen abstraction direct processes?

Geng

Huang

et al. 2006

Chemical Physics

View full text Add to dashboard Cite

H Atom Branching Ratios from the Reactions of CH with C₂H₂, C₂H₄, C₂H₆, and neo-C₅H₁₂ at Room Temperature and 25 Torr

Cited by 48 publications

References 47 publications

Cyclic Versus Linear Isomers Produced by Reaction of the Methylidyne Radical (CH) with Small Unsaturated Hydrocarbons

Cyclic Versus Linear Isomers Produced by Reaction of the Methylidyne Radical (CH) with Small Unsaturated Hydrocarbons

Theoretical mechanistic study of the reaction of the methylidyne radical with methylacetylene

F/Cl + C2H2 reactions: Are the addition and hydrogen abstraction direct processes?

Contact Info

Product

Resources

About