Stereocontrol of the red light induced photoepoxidation of 2-butenes by nitrogen dioxide in solid Ar

Journal Article · Thu Nov 02 04:00:00 EST 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100359a028· OSTI ID:6737837

Nakata, M; Frei, H ^[1]

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1. Lawrence Berkeley Lab., CA (USA)

Photooxidation of cis-2-butene was initiated in an inert gas matrix by exciting cis-2-butene-NO{sub 2} pairs at red, yellow, and green wavelengths (NO{sub 2} {sup 2}B{sub 2} {r arrow} X{sup 2}A{sub 1}). Chemical reaction was monitored by FT-IR spectroscopy, and emission from an Ar ion or a tuned CW dye laser was used for photolysis. As in the case of the trans-2-butene + NO{sub 2} reaction reported earlier, 2,3-epoxybutane was the only final oxidation product observed upon direct photolysis of reactant pairs. While in the case of the trans-2-butene reaction stereochemical retention was complete, we found in the cis case 85% of the epoxide with retained configuration when conducting the reaction at low matrix concentration. This fraction decreased with increasing reactant to matrix ratio. Infrared bands of two conformers of a butyl nitrite radical were observed concurrently with the epoxide, one syn, the other anti with respect to conformation (CH{sub 3} groups) about the central CC bond. A correlation was found between the syn to anti nitrite radical and the cis to trans epoxide ratios, suggesting a common transient precursor. It is most probably an oxirane biradical, whose conformation determines the stereochemistry of the epoxide product. The photolysis wavelength dependence of the product growth kinetics was studied, and relative reaction of efficiencies so obtained are shown to give insight into aspects of the dynamics of the reaction that relate to the observed product and stereospecificity.

• OSTI ID: 6737837
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:22; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKENES
BUTENES
CHALCOGENIDES
CHEMICAL REACTIONS
DATA
DATA ANALYSIS
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
INFRARED SPECTRA
MEASURING INSTRUMENTS
MEASURING METHODS
NITROGEN COMPOUNDS
NITROGEN DIOXIDE
NITROGEN OXIDES
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
SPECTRA
STEREOCHEMISTRY