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Author(s):   Sivaramakrishnan, R.; Michael, J.V.; Klippenstein, S.J.
Title:   Direct Observation of Roaming Radicals in the Thermal Decomposition of Acetaldehyde
Journal:   J. Phys. Chem. A
Volume:   114
Page(s):   755 - 764
Year:   2010
Reference type:   Journal article
Squib:   2010SIV/MIC755-764

Reaction:   CH3CHOH2C=C=O + H2
Reaction order:   1
Temperature:   1405 - 1799 K
Pressure:  7.87E-3 - 4.25E-2 bar
Rate expression:   no rate data available
Category:  Experiment
Data type:   Derived from fitting to a complex mechanism
Pressure dependence:   Rate constant is pressure dependent
Experimental procedure:   Shock tube
Excitation technique:   Thermal
Time resolution:   In real time
Analytical technique:   Vis-UV absorption
Comments:   The thermal dissociation of acetaldehyde has been studied with the reflected shock tube technique using H(D)-atom atomic resonance absorption spectrometry detection. Both the total decomposition rate and the branching to radical versus molecular channels were determined. This branching provides a direct measure of the contribution from the roaming radical mechanism since the contributions from the usual tight transition states are predicted by theory to be negligible. Rate constants for the radical channel (CH3 + HCO products) and the sum of the molecular channels (CH4 + CO and CH2CO + H2 products) are reported in tables. No Arrhenius expressions are derived. The results are compared with those of an accompanying theoretical paper.

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