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Title: The 213. 8-nm photochemistry of gaseous 1,3-butadiene and the structure of some C sub 3 H sub 3 radicals

Abstract

A systematic study of the 213.8-nm (zinc line) photochemistry of 1,3-butadiene has been made either in the absence or in the presence of various additives--such as radical scavengers (O{sub 2}, NO, DI) and collisional quenchers--in the gas phase (pressure between 1 and 500 Torr). The major fate of the photoexcited 1,3-butadiene molecule is isomerization to the 1,2-butadiene structure which may then decompose to methyl and C{sub 3}H{sub 3} radicals ({Phi} = 0.64 {plus minus} 0.04 at 1 Torr of 1,3-butadiene). Minor processes include decomposition to the acetylene + ethylene couple ({Phi} = 0.22 {plus minus} 0.02) or to vinylacetylene ({Phi} = 0.038 {plus minus} 0.003) and molecular hydrogen. These two minor processes occur from different excited states. Some 2-butyne ({Phi} < 0.015) is formed by a unimolecular isomerization process. The photolysis of 1,3-butadiene-1,1,4,4-d{sub 4} indicates that at least three different intermediates are involved in the formation of molecular ethylene and acetylene. The C{sub 3}H{sub 3} radicals are not easily intercepted by DI: k(C{sub 3}H{sub 3} + DI) = 0.09 {plus minus} 0.03. Also at 21{degree}C and for (DI)/(1,3-butadiene) = 10, the highest ratio used {Phi}(allene + propyne)/{Phi}(CH{sub 3}D) = 0.72 and a fraction of the C{sub 3}H{sub 3} radicals aremore » still not accounted for (reaction with 1,3-butadiene and/or recombination ). The relative energies obtained by ab initio RHF-SCF geometry optimizations for the doublet electronic state of the C{sub 3}H{sub 3} radical structures are E(propargyl) < E(propyn-1-yl) < E(cyclopropen-1-yl) < E(allenyl). General valence bond geometry optimizations and a multiconfigurational self-consistent-field surface scan also show that the propargyl species ({sup 2}B{sub 1} state) is the lowest energy one. There are probably at least two distinct C{sub 3}H{sub 3} radical structures (different states) present in the far-UV photolysis of 1,3-butadiene.« less

Authors:
;  [1];  [2];  [3]
  1. Universite du Quebec a Chicoutimi (Canada)
  2. Universite Libre de Bruxelles (Belgium)
  3. Memorial Univ. of Newfoundland, Saint-John's (Canada)
Publication Date:
OSTI Identifier:
6946646
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry; (USA)
Additional Journal Information:
Journal Volume: 94:1; Journal ID: ISSN 0022-3654
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BUTADIENE; PHOTOCHEMISTRY; CALCULATION METHODS; COMPUTER CODES; DATA ANALYSIS; ETHYLENE; EXPERIMENTAL DATA; MEASURING INSTRUMENTS; MEASURING METHODS; PROPYL RADICALS; STRUCTURAL CHEMICAL ANALYSIS; THEORETICAL DATA; ALKENES; ALKYL RADICALS; CHEMISTRY; DATA; DIENES; HYDROCARBONS; INFORMATION; NUMERICAL DATA; ORGANIC COMPOUNDS; POLYENES; RADICALS; 400500* - Photochemistry

Citation Formats

Collin, G J, Deslauriers, H, De Mare, G R, and Poirier, R A. The 213. 8-nm photochemistry of gaseous 1,3-butadiene and the structure of some C sub 3 H sub 3 radicals. United States: N. p., 1990. Web. doi:10.1021/j100364a020.
Collin, G J, Deslauriers, H, De Mare, G R, & Poirier, R A. The 213. 8-nm photochemistry of gaseous 1,3-butadiene and the structure of some C sub 3 H sub 3 radicals. United States. https://doi.org/10.1021/j100364a020
Collin, G J, Deslauriers, H, De Mare, G R, and Poirier, R A. 1990. "The 213. 8-nm photochemistry of gaseous 1,3-butadiene and the structure of some C sub 3 H sub 3 radicals". United States. https://doi.org/10.1021/j100364a020.
@article{osti_6946646,
title = {The 213. 8-nm photochemistry of gaseous 1,3-butadiene and the structure of some C sub 3 H sub 3 radicals},
author = {Collin, G J and Deslauriers, H and De Mare, G R and Poirier, R A},
abstractNote = {A systematic study of the 213.8-nm (zinc line) photochemistry of 1,3-butadiene has been made either in the absence or in the presence of various additives--such as radical scavengers (O{sub 2}, NO, DI) and collisional quenchers--in the gas phase (pressure between 1 and 500 Torr). The major fate of the photoexcited 1,3-butadiene molecule is isomerization to the 1,2-butadiene structure which may then decompose to methyl and C{sub 3}H{sub 3} radicals ({Phi} = 0.64 {plus minus} 0.04 at 1 Torr of 1,3-butadiene). Minor processes include decomposition to the acetylene + ethylene couple ({Phi} = 0.22 {plus minus} 0.02) or to vinylacetylene ({Phi} = 0.038 {plus minus} 0.003) and molecular hydrogen. These two minor processes occur from different excited states. Some 2-butyne ({Phi} < 0.015) is formed by a unimolecular isomerization process. The photolysis of 1,3-butadiene-1,1,4,4-d{sub 4} indicates that at least three different intermediates are involved in the formation of molecular ethylene and acetylene. The C{sub 3}H{sub 3} radicals are not easily intercepted by DI: k(C{sub 3}H{sub 3} + DI) = 0.09 {plus minus} 0.03. Also at 21{degree}C and for (DI)/(1,3-butadiene) = 10, the highest ratio used {Phi}(allene + propyne)/{Phi}(CH{sub 3}D) = 0.72 and a fraction of the C{sub 3}H{sub 3} radicals are still not accounted for (reaction with 1,3-butadiene and/or recombination ). The relative energies obtained by ab initio RHF-SCF geometry optimizations for the doublet electronic state of the C{sub 3}H{sub 3} radical structures are E(propargyl) < E(propyn-1-yl) < E(cyclopropen-1-yl) < E(allenyl). General valence bond geometry optimizations and a multiconfigurational self-consistent-field surface scan also show that the propargyl species ({sup 2}B{sub 1} state) is the lowest energy one. There are probably at least two distinct C{sub 3}H{sub 3} radical structures (different states) present in the far-UV photolysis of 1,3-butadiene.},
doi = {10.1021/j100364a020},
url = {https://www.osti.gov/biblio/6946646}, journal = {Journal of Physical Chemistry; (USA)},
issn = {0022-3654},
number = ,
volume = 94:1,
place = {United States},
year = {Thu Jan 11 00:00:00 EST 1990},
month = {Thu Jan 11 00:00:00 EST 1990}
}