TY - JOUR
T1 - Kinetics of the hydrogen atom abstraction reactions from 1-butanol by hydroxyl radical
T2 - Theory matches experiment and more
AU - Seal, Prasenjit
AU - Oyedepo, Gbenga
AU - Truhlar, Donald G
PY - 2013/1/17
Y1 - 2013/1/17
N2 - In the present work, we study the H atom abstraction reactions by hydroxyl radical at all five sites of 1-butanol. Multistructural variational transition state theory (MS-VTST) was employed to estimate the five thermal rate constants. MS-VTST utilizes a multifaceted dividing surface that accounts for the multiple conformational structures of the transition state, and we also include all the structures of the reactant molecule. The vibrational frequencies and minimum energy paths (MEPs) were computed using the M08-HX/MG3S electronic structure method. The required potential energy surfaces were obtained implicitly by direct dynamics employing interpolated variational transition state theory with mapping (IVTST-M) using a variational reaction path algorithm. The M08-HX/MG3S electronic model chemistry was then used to calculate multistructural torsional anharmonicity factors to complete the MS-VTST rate constant calculations. The results indicate that torsional anharmonicity is very important at higher temperatures, and neglecting it would lead to errors of 26 and 32 at 1000 and 1500 K, respectively. Our results for the sums of the site-specific rate constants agree very well with the experimental values of Hanson and co-workers at 896-1269 K and with the experimental results of Campbell et al. at 292 K, but slightly less well with the experiments of Wallington et al., Nelson et al., and Yujing and Mellouki at 253-372 K; nevertheless, the calculated rates are within a factor of 1.61 of all experimental values at all temperatures. This gives us confidence in the site-specific values, which are currently inaccessible to experiment.
AB - In the present work, we study the H atom abstraction reactions by hydroxyl radical at all five sites of 1-butanol. Multistructural variational transition state theory (MS-VTST) was employed to estimate the five thermal rate constants. MS-VTST utilizes a multifaceted dividing surface that accounts for the multiple conformational structures of the transition state, and we also include all the structures of the reactant molecule. The vibrational frequencies and minimum energy paths (MEPs) were computed using the M08-HX/MG3S electronic structure method. The required potential energy surfaces were obtained implicitly by direct dynamics employing interpolated variational transition state theory with mapping (IVTST-M) using a variational reaction path algorithm. The M08-HX/MG3S electronic model chemistry was then used to calculate multistructural torsional anharmonicity factors to complete the MS-VTST rate constant calculations. The results indicate that torsional anharmonicity is very important at higher temperatures, and neglecting it would lead to errors of 26 and 32 at 1000 and 1500 K, respectively. Our results for the sums of the site-specific rate constants agree very well with the experimental values of Hanson and co-workers at 896-1269 K and with the experimental results of Campbell et al. at 292 K, but slightly less well with the experiments of Wallington et al., Nelson et al., and Yujing and Mellouki at 253-372 K; nevertheless, the calculated rates are within a factor of 1.61 of all experimental values at all temperatures. This gives us confidence in the site-specific values, which are currently inaccessible to experiment.
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U2 - 10.1021/jp310910f
DO - 10.1021/jp310910f
M3 - Article
C2 - 23244297
AN - SCOPUS:84872515290
SN - 1089-5639
VL - 117
SP - 275
EP - 282
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 2
ER -