Infrared multiphoton decomposition of cis-2-pentene and 3-methyl-cis-2-pentene

Journal Article · Thu Oct 23 04:00:00 EDT 1986 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100280a042· OSTI ID:7169873

Back, R A; Collin, G J

The infrared multiphoton (IRMP) decomposition of cis-2-pentene and 3-methyl-cis-2-pentene has been studied in order to compare the fragmentation pattern of the photoexcited molecules with that observed in the vacuum ultraviolet photolysis. The decompositions were studied at pressures from 0.2 to 5 Torr, using a pulsed CO/sub 2/ laser weakly focused to five fluences from about 5 to 20 J/cm/sup 2/ in the focal region. The IRMP decomposition of both molecules can be explained on the basis of a primary dissociation of a ..beta..C-C bond, followed by secondary fragmentation of the allylic moiety and the usual stabilizing processes and radical-radical reactions. The fragmentation patterns are generally similar to those observed in the vacuum UV photolysis, and the present results simply show the possibility that the ground state is involved in the vacuum UV photolysis; the behavior of the latter system itself lends support to this. Differences between the two systems can be explained by the higher initial energy of the molecules excited in the vacuum UVC. Some isomerization was also observed, mostly arising from radical-radical reactions. The formation of 1-pentene, however, indicates that the sigmatropic 1,3 hydrogen atom transfer can take place via the vibrationally excited ground state of cis-2-pentene. Conversely, 2-methyl-1-butene is not observed; its formation requires an internal methylene shift, and its occurrence in the vacuum UV photolysis suggests its direct formation from an electronically excited state.

• Research Organization: National Research Council of Canada, Ottawa, Ontario
• OSTI ID: 7169873
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 90:22; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ALKENES
CARBON DIOXIDE LASERS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
DATA
DECOMPOSITION
EXPERIMENTAL DATA
GAS LASERS
HYDROCARBONS
INFORMATION
LASERS
MULTI-PHOTON PROCESSES
NUMERICAL DATA
ORGANIC COMPOUNDS
PENTENES
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PRESSURE DEPENDENCE
REACTION INTERMEDIATES
YIELDS