Combined Crossed Molecular Beam and ab Initio Investigation of the Multichannel Reaction of Boron Monoxide (BO; X2Σ+) with Propylene (CH3CHCH2; X1A′): Competing Atomic Hydrogen and Methyl Loss Pathways

被引:3
作者
Maity, Surajit [1 ]
Dangi, Beni B. [1 ]
Parker, Dorian S. N. [1 ]
Kaiser, Ralf I. [1 ]
An, Yi [2 ]
Sun, Bing-Jim [2 ]
Chang, A. H. H. [2 ]
机构
[1] Univ Hawaii Manoa, Dept Chem, Honolulu, HI 96822 USA
[2] Natl Dong Hwa Univ, Dept Chem, Shoufeng 974, Hualien, Taiwan
关键词
EXTENDED COMBUSTION MODEL; HYDROCARBON MOLECULES; CHEMICAL-DYNAMICS; CN(X (2)SIGMA(+)); CYANO RADICALS; DIMETHYLACETYLENE CH3CCCH3; INFRARED-SPECTRA; HIGH-INTENSITY; MASS-SPECTRUM; CARBON-ATOMS;
D O I
10.1021/jp507001r
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The reaction dynamics of boron monoxide ((BO)-B-11; X-2 Sigma(+)) with propylene (CH3CHCH(2); X(1)A') were investigated under single collision conditions at a collision energy of 22.5 +/- 1.3 kJ mol(-1). The crossed molecular beam investigation combined with ab initio electronic structure and statistical (RRKM) calculations reveals that the reaction follows indirect scattering dynamics and proceeds via the barrierless addition of boron monoxide radical with its radical center located at the boron atom. This addition takes place to either the terminal carbon atom (C1) and/or the central carbon atom (C2) of propylene reactant forming (BOC3H6)-B-11 intermediate(s). The long-lived 11BOC(3)H(6) doublet intermediate(s) underwent unimolecular decomposition involving at least three competing reaction mechanisms via an atomic hydrogen loss from the vinyl group, an atomic hydrogen loss from the methyl group, and a methyl group elimination to form cis-/trans-1-propenyl-oxo-borane ((CH3CHCHBO)-B-11), 3-propenyl-oxo-borane ((CH2CHCH2BO)-B-11), and ethenyl-oxo-borane ((CH2CHBO)-B-11), respectively. Utilizing partially deuterated propylene (CD3CHCH2 and CH3CDCD2), we reveal that the loss of a vinyl hydrogen atom is the dominant hydrogen elimination pathway (85 +/- 10%) forming cis-/trans-1-propenyl-oxo-borane, compared to the loss of a methyl hydrogen atom (15 +/- 10%) leading to 3-propenyl-oxo-borane. The branching ratios for an atomic hydrogen loss from the vinyl group, an atomic hydrogen loss from the methyl group, and a methyl group loss are experimentally derived to be 26 +/- 8%:5 +/- 3%:69 +/- 15%, respectively; these data correlate nicely with the branching ratios calculated via RRKM theory of 19%:5%:75%, respectively.
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页码:9632 / 9645
页数:14
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