Photochemistry of cycloalkeneter dot NO sub 2 collisional pairs in a cryogenic matrix: Chemical trapping of cycloalkene oxirane biradical conformers, and comparison of product control for excitation above and below the NO sub 2 dissociation threshold

Journal Article · Thu Apr 04 00:00:00 EST 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100160a007· OSTI ID:5542857

Fitzmaurice, D J; Frei, H ^[1]

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1. Lawrence Berkeley Lab., CA (United States)

Oxygen atom transfer from NO{sub 2} to cyclohexene and from NO{sub 2} to cyclopentene was induced by excitation of reactant pairs isolated in solid Ar by light in the wavelength range between 610 and 355 nm. Continuous wave dye, Ar ion, and ND:YAG lasers were used as photolysis sources, and the chemistry was monitored by Fourier transform infrared spectroscopy. The O atom transfer path accessible at wavelengths longer than the 398-nm NO{sub 2} dissociation limit led to cycloalkene oxide as the only final oxidation product. The reaction threshold was at 610 nm. In the case of cyclohexene + NO{sub 2}, two cyclohexyl nitrite radical diastereomers were produced concurrently with the epoxide. Infrared analysis based on {sup 18}O and {sup 15}N isotopic substitution, visible light induced wavelength-selective photodissociation, and matrix annealing experiments indicate that the two stereoisomers were produced concurrently with the epoxide. Infrared analysis based on {sup 18}O and {sup 15}N isotopic substitution, visible light induced wavelength-selective photodissociation, and matrix annealing experiments indicate that the two stereoisomers are cyclohexyl nitrite radical chair conformers with an equatorial and an axial C-O bond, respectively. Since these are transient cyclohexene oxirane biradicals chemically trapped by reaction with NO cage coproduct according to the previously established reaction mechanism, it is concluded that cyclohexene oxidation proceeds along two diastereomeric paths. In the case of the cyclopentene + NO{sub 2} reaction only a single cyclopentyl nitrite radical stereoisomer is observed, presumably because of the very low barrier to pseudorotation of the pentyl ring.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5542857
• Journal Information: Journal of Physical Chemistry; (United States), Vol. 95:7; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CYCLOALKENES
PHOTOCHEMISTRY
NITROGEN DIOXIDE
ABSORPTION SPECTROSCOPY
ALCOHOLS
ALKYL RADICALS
ANNEALING
EPOXIDES
EXPERIMENTAL DATA
HEXENES
INFRARED SPECTRA
ISOTOPIC EXCHANGE
KETONES
LASER RADIATION
MATRIX ISOLATION
MOLECULAR STRUCTURE
MOLECULE COLLISIONS
NITROGEN 15
OXYGEN
OXYGEN 18
PENTENES
PHOTOCHEMICAL REACTIONS
SAMPLE PREPARATION
TEMPERATURE RANGE 0013-0065 K
ULTRAVIOLET SPECTRA
VISIBLE RADIATION
VISIBLE SPECTRA
ALKENES
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
COLLISIONS
DATA
ELECTROMAGNETIC RADIATION
ELEMENTS
EVEN-EVEN NUCLEI
HEAT TREATMENTS
HYDROCARBONS
HYDROXY COMPOUNDS
INFORMATION
ISOTOPES
LIGHT NUCLEI
NITROGEN COMPOUNDS
NITROGEN ISOTOPES
NITROGEN OXIDES
NONMETALS
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
RADIATIONS
RADICALS
SPECTRA
SPECTROSCOPY
STABLE ISOTOPES
TEMPERATURE RANGE
400500* - Photochemistry