Enol Formation and Ring-Opening in OH-Initiated Oxidation of Cycloalkenes

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• 作者：Giovanni Meloni ; Talitha M. Selby ; David L. Osborn ; Craig A. Taatjes
• 刊名：Journal of Physical Chemistry A
• 出版年：2008
• 出版时间：December 25, 2008
• 年：2008
• 卷：112
• 期：51
• 页码：13444-13451
• 全文大小：226K
• 年卷期：v.112,no.51(December 25, 2008)
• ISSN：1520-5215

文摘

Photolytic OH-initiated oxidation of cyclopentene, cyclohexene, and 1,4-cyclohexadiene have been investigated by using tunable synchrotron photoionization mass spectrometry. Electronic structure calculations (CBS-QB3) are employed in Franck−Condon (FC) spectral simulations of the photoionization efficiency curves (PIE) of the observed products. Cyclopentenol (cyclopenten-1-ol, 1-c-C₅H₇OH) and its isomers cyclopenten-2-ol (2-c-C₅H₇OH) and cyclopentanone (c-C₅H₈O), are detected from OH-initiated cyclopentene oxidation. The measured adiabatic ionization energy (AIE) of 1-c-C₅H₇OH is 8.4(±0.1) eV, and that of 2-c-C₅H₇OH is 9.5(±0.1) eV. The calculated AIE of possible cyclopentene oxidation products cis-1,2-epoxycyclopentane and 2,3-epoxycyclopentanol is 9.97 and 9.44 eV, respectively. Product spectra from OH-initiated oxidation of cyclohexene and cyclohexa-1,4-diene show a substantial contribution from linear aldehydes, indicating a prominent role for ring opening. Implications for the oxidation chemistry of cycloalkenes are briefly discussed.