Visible light-induced oxygen transfer from nitrogen dioxide to ethyne and propyne in a cryogenic matrix. 2. Mechanism and regioselectivity

Journal Article · Thu Nov 24 04:00:00 EST 1994 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100098a007· OSTI ID:6730510

Harrison, J A; Frei, H ^[1]

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

The kinetics of visible light-induced oxidation of ethyne and propyne by NO[sub 2] in solid Ar has been monitored as a function of photolysis wavelength. CW dye and Ar ion laser emission was used for irradiation, and FT-infrared spectroscopy for the measurement of product growth. Determination of the wavelength dependence of quantum efficiencies from the kinetic measurements revealed that the photolysis threshold of HC[triple bond]CH + NO[sub 2] lies approximately 6 kcal mol[sup [minus]1] higher than that of CH[sub 3]C[triple bond]CH + NO[sub 2]. This and other parameters derived from the product growth measurements, and the formyl methyl iminoxy radical trapped in the case of the CH[sub 3]C[triple bond]CH + NO[sub 2] reaction are interpreted in terms of a direct O transfer mechanism. The proposed path involves large-amplitude O transfer from photoexcited NO[sub 2] to the C[triple bond]C group to yield a transient ketocarbene. Formation of iminoxy radical is attributed to trapping of the ketocarbene by NO cage coproduct, which is in competition with Wolff rearrangement to yield ketene. From the structure of the iminoxy radical, it is inferred that the photoinduced O transfer from NO[sub 2] to the unsymmetrical C[triple bond]C bond of propyne is completely regioselective, leading exclusively to the carbene transient with oxygen at the terminal carbon. 29 refs., 7 figs.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6730510
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 98:47; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102 -- Chemical & Spectral Procedures
400201* -- Chemical & Physicochemical Properties
400500 -- Photochemistry
ACETYLENE
ALKYNES
ARGON
CHALCOGENIDES
CHEMICAL REACTIONS
CRYOGENICS
DECOMPOSITION
DEUTERIUM
DYE LASERS
EFFICIENCY
ELEMENTS
EVEN-EVEN NUCLEI
FLUIDS
GASES
HYDROCARBONS
HYDROGEN ISOTOPES
INFRARED SPECTRA
ISOTOPES
LASERS
LIGHT NUCLEI
LIQUID LASERS
NITROGEN 15
NITROGEN COMPOUNDS
NITROGEN DIOXIDE
NITROGEN ISOTOPES
NITROGEN OXIDES
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
OXIDES
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PROPYNE
QUANTUM EFFICIENCY
RADICALS
RARE GASES
REACTION INTERMEDIATES
SPECTRA
STABLE ISOTOPES