Synchrotron photoionization measurements of OH-initiated cyclohexene oxidation: ring-preserving products in OH + cyclohexene and hydroxycyclohexyl + O2 reactions.
Earlier synchrotron photoionization mass spectrometry experiments suggested a prominent ring-opening channel in the OH-initiated oxidation of cyclohexene, based on comparison of product photoionization spectra with calculated spectra of possible isomers. The present work re-examines the OH + cyclohexene reaction, measuring the isomeric products of OH-initiated oxidation of partially and fully deuterated cyclohexene. In particular, the directly measured photoionization spectrum of 2-cyclohexen-1-ol differs substantially from the previously calculated Franck-Condon envelope, and the product spectrum can be fit with no contribution from ring-opening. Measurements of H(2)O(2) photolysis in the presence of C(6)D(10) establish that the addition-elimination product incorporates the hydrogen atom from the hydroxyl radical reactant and loses a hydrogen (a D atom in this case) from the ring. Investigation of OH + cyclohexene-4,4,5,5-d(4) confirms this result and allows mass discrimination of different abstraction pathways. Products of 2-hydroxycyclohexyl-d(10) reaction with O(2) are observed upon adding a large excess of O(2) to the OH + C(6)D(10) system.
Department of Chemistry, University of San Francisco, San Francisco, California 94117, USA.
Amelia W
AW
Ray
Craig A
CA
Taatjes
Oliver
O
Welz
David L
DL
Osborn
Giovanni
G
Meloni
D003511:Cyclohexanols / Q000737:chemistry*; D053138:Cyclohexenes / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry*; D013058:Mass Spectrometry; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D055668:Photochemical Processes; D017356:Synchrotrons
D003511:Cyclohexanols; D053138:Cyclohexenes; C052568:cyclohexene; D017665:Hydroxyl Radical; D010100:Oxygen