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Author(s):   Goulay, F.; Trevitt, A.J.; Savee, J.D.; Bouwman, J.; Osborn, D.L.; Taatjes, C.A.; Wilson, K.R.; Leone, S.R.
Title:   Product Detection of the CH Radical Reaction with Acetaldehyde
Journal:   J. Phys. Chem. A
Volume:   116
Page(s):   6091 - 6106
Year:   2012
Book Title:   ''
Editor:   ''
Publisher:   ''
Publisher address:   ''
Comments:   ''
Reference type:   Journal article
Squib:   2012GOU/TRE6091-6106

Reaction:   CH3CHO + ·CHCO + ·C2H5
Reaction order:   2
Temperature:   298 K
Pressure:  5.33E-3 bar
Rate expression:   no rate data available
Category:  Experiment
Data type:   Mechanistic information only
Pressure dependence:   None reported
Experimental procedure:   Static or low flow - Data taken vs time
Excitation technique:   Flash photolysis (laser or conventional)
Time resolution:   In real time
Analytical technique:   Mass spectrometry
Comments:   The reaction of the methylidyne radical (CH) with acetaldehyde was studied at room temperature and at a pressure of 4 Torr (533.3 Pa) using a multiplexed photoionization mass spectrometer coupled to the tunable vacuum ultraviolet synchrotron radiation of the Advanced Light Source at Lawrence Berkeley National Laboratory. Five reaction exit channels were observed corresponding to elimination of methylene (CH2), elimination of a formyl radical (HCO), elimination of carbon monoxide (CO), elimination of a methyl radical (CH3), and elimination of a hydrogen atom. Analysis of the photoionization yields versus photon energy for the reaction of CH and CD radicals with acetaldehyde and CH radical with partially deuterated acetaldehyde (CD3CHO) provides fine details about the reaction mechanism. The CH2 elimination channel is found to preferentially form the acetyl radical by removal of the aldehydic hydrogen. The insertion of the CH radical into a C−H bond of the methyl group of acetaldehyde is likely to lead to a C3H5O reaction intermediate that can isomerize by β-hydrogen transfer of the aldehydic hydrogen atom and dissociate to form acrolein + H or ketene + CH3, which are observed directly. Cycloaddition of the radical onto the carbonyl group is likely to lead to the formation of the observed products, methylketene, methyleneoxirane, and acrolein.

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