Isomerization of 4-vinylcyclohexene radical cation. A tandem mass spectrometry study

Journal Article · Tue Feb 07 23:00:00 EST 1995 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00110a036· OSTI ID:6455602

Vollmer, D; Rempel, D L; Gross, M L ^[1]; Williams, F ^[2]

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1. Univ. of Nebraska, Lincoln, NE (United States)
2. Univ. of Tennessee, Knoxville, TN (United States)

Investigation by matrix-isolation ESR has shown that 4-vinylcyclohexene, 1, surprisingly undergoes isomerization to the bicyclo[3.2.1]oct-2-ene ion, 3. Here we demonstrate the occurrence of this isomerization in the gas phase by use of tandem (MS/MS) sector and Fourier transform (FT) mass spectrometries. The radical cations of 4-vinylcyclohexene (IE = 8.93 eV) or bicyclo[3.2.1]oct-2-ene (approximately 14 kcal/mol more stable than that of 4-vinylcyclohexene) were formed, in separate trials, in a chemical ionization (CI) source by electron ionization (EI). The radical cations were then studied by obtaining their collisionally activated decomposition (CAD) spectra. The CAD spectra are similar, indicating that the isomerization has occurred. Both the sector and the FT mass spectrometer results reflect those obtained in the matrix-isolation ESR investigation. That is isomerizes to 3 at high internal energy, but is stable at low internal energy. Two mechanisms explain this rearrangement. The second mechanism is questionable because the most stable olefin radical cation formed from 5 is that of bicyclo[2.2.2]-2-octene, which gives different ESR and CAD spectra than those of 1 or 3. The CAD spectrum of bicyclo[2.2.2]-2-octene radical cation indicates that the retro-Diels-Alder loss of ethylene is more facile than that from 1 or 3. 18 refs., 3 figs.

• DOE Contract Number: FG05-88ER13852
• OSTI ID: 6455602
• Journal Information: Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 117:5; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102 -- Chemical & Spectral Procedures
400201* -- Chemical & Physicochemical Properties
664300 -- Atomic & Molecular Physics-- Collision Phenomena-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ALKYL RADICALS
CATIONS
CHARGED PARTICLES
CHEMICAL REACTIONS
COLLISIONS
DECOMPOSITION
IONS
ISOMERIZATION
MASS SPECTRA
MASS SPECTROMETERS
MEASURING INSTRUMENTS
RADICALS
SPECTRA
SPECTROMETERS
VINYL RADICALS