Photodissociation and photoisomerization dynamics of CH{sub 2}=CHCHO in solution

Journal Article · Sun Mar 28 00:00:00 EDT 2010 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.3352421· OSTI ID:21559846

Weiqiang, Wu; Chunfan, Yang; Hongmei, Zhao; Kunhui, Liu; Hongmei, Su ^[1]

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1. State Key Laboratory of Molecular Reaction Dynamics, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

By means of time-resolved Fourier transform infrared absorption spectroscopy, we have investigated the 193 nm photodissociation and photoisomerization dynamics of the prototype molecule of {alpha},{beta}-enones, acrolein (CH{sub 2}=CHCHO) in CH{sub 3}CN solution. The primary photolysis channels and absolute branching ratios are determined. The most probable reaction mechanisms are clarified by control experiments monitoring the product yields varied with the triplet quencher addition. The predominant channel is the 1,3-H migration yielding the rearrangement product CH{sub 3}CH=C=O with a branching ratio of 0.78 and the less important channel is the {alpha} cleavage of C-H bond yielding radical fragments CH{sub 2}=CHCO+H with a branching ratio of only 0.12. The 1,3-H migration is strongly suggested to correlate with the triplet {sup 3}({pi}{pi}{sup *}) state rather than the ground S{sub 0} state and the {alpha} cleavage of C-H bond is more likely to proceed in the singlet S{sub 1} {sup 1}(n{pi}{sup *}) state. From the solution experiments we have not only acquired clues clarifying the previous controversial mechanisms, but also explored different photochemistry in solution. Compared to the gas phase photolysis which is dominated by photodissociation channels, the most important channel in solution is the photoisomerization of 1,3-H migration. The reason leading to the different photochemistry in solution is further ascribed to the solvent cage effect.

• OSTI ID: 21559846
• Journal Information: Journal of Chemical Physics, Vol. 132, Issue 12; Other Information: DOI: 10.1063/1.3352421; (c) 2010 American Institute of Physics; ISSN 0021-9606
• Country of Publication: United States
• Language: English

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37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION SPECTROSCOPY
ACETONITRILE
ACROLEIN
BRANCHING RATIO
CHEMICAL BONDS
CLEAVAGE
DISSOCIATION
FOURIER TRANSFORMATION
GROUND STATES
INFRARED SPECTRA
ISOMERIZATION
MATHEMATICAL SOLUTIONS
MIGRATION
PHOTOCHEMISTRY
PHOTOLYSIS
REACTION KINETICS
SOLUTIONS
SOLVENTS
TIME RESOLUTION
TRIPLETS
ALDEHYDES
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
DIMENSIONLESS NUMBERS
DISPERSIONS
ENERGY LEVELS
HOMOGENEOUS MIXTURES
INTEGRAL TRANSFORMATIONS
KINETICS
MICROSTRUCTURE
MIXTURES
MULTIPLETS
NITRILES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
RESOLUTION
SPECTRA
SPECTROSCOPY
TIMING PROPERTIES
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