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Title: Enhanced H-atom Abstraction from Pinonaldehyde, Pinonic Acid, Pinic Acid, and Related Compounds: Theoretical Study of C-H Bond Strengths
Journal: Phys. Chem. Chem. Phys.
Volume: 4
Page(s): 467 - 472
Year: 2002
Reference type: Journal article
Squib: 2002VER/PEE467-472
Reaction:
(CH3)2CO + ·OH → CH3C(O)CH2(·) + H2O
Reaction order:
2
Reference reaction:
(CH3)2CO + ·OH → Products
Reference reaction order:
2
Temperature:
290
K
Rate expression:
9.5x10-1
Rate constant is a lower limit.
Category: Experiment
Data type:
Mechanistic information only
Pressure dependence:
None reported
Experimental procedure:
Flow tube - Data taken vs distance
Excitation technique:
Discharge
Time resolution:
By end product analysis
Analytical technique:
Mass spectrometry
Comments:
The possible OH addition/CH3 elimination channel was found to be < 5% of reaction, with no significant formation of acetic acid detected. Reaction proceeds via H abstraction.
In addition to the experimental work, the potential energy surface was characterized at the B3LYP-DFT/6-31G(d,p) and B3LYP-DFT/6-311++G(d,p) levels of theory, with single-point CCSD(T)/6-311++G(2d,2p) energy calculations. At all levels, the barrier for OH-addition was found to be 6±0.5 kcal/mol, at least 2.5 kcal/mol higher than that for the H-abstraction channels. Transition state theory and RRKM - master equation calculations suggest the OH-addition channel is negligible at all relevant atmospheric temperatures.
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