A Direct Dynamics Trajectory Study of F- + CH3OOH Reactive Collisions Reveals a Major Non-IRC Reaction Path

A direct dynamics simulation at the B3LYP/6-311+G(d,p) level of theory was used to study the F- + CH3OOH reaction dynamics. The simulations are in excellent agreement with a previous experimental study (J. Am. Chem. Soc. 2002, 124, 3196). Two product channels, HF + CH2O + OH- and HF + CH3OO-, are ob...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2007-08, Vol.129 (32), p.9976-9985
Main Authors: López, José G, Vayner, Grigoriy, Lourderaj, Upakarasamy, Addepalli, Srirangam V, Kato, Shuji, deJong, Wibe A, Windus, Theresa L, Hase, William L
Format: Article
Language:English
Subjects:
CHEMICAL REACTION KINETICS
DISSOCIATION
DOUBLE BONDS
Environmental Molecular Sciences Laboratory
FLUORINE
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
PEROXIDES
POTENTIAL ENERGY
REACTION INTERMEDIATES
SIMULATION
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Summary:A direct dynamics simulation at the B3LYP/6-311+G(d,p) level of theory was used to study the F- + CH3OOH reaction dynamics. The simulations are in excellent agreement with a previous experimental study (J. Am. Chem. Soc. 2002, 124, 3196). Two product channels, HF + CH2O + OH- and HF + CH3OO-, are observed. The former dominates and occurs via an ECO2 mechanism in which F- attacks the CH3− group, abstracting a proton. Concertedly, a carbon−oxygen double bond is formed and OH- is eliminated. Somewhat surprisingly this is not the reaction path, predicted by the intrinsic reaction coordinate (IRC), which leads to a deep potential energy minimum for the CH2(OH)2···F- complex followed by dissociation to HF + CH2(OH)O-. None of the direct dynamics trajectories followed this path, which has an energy release of −63 kcal/mol and is considerably more exothermic than the ECO2 path whose energy release is −27 kcal/mol. Other product channels not observed, and which have a lower energy than that for the ECO2 path, are F- + CO + H2 + H2O (−43 kcal/mol), F- + CH2O + H2O (−51 kcal/mol), and F- + CH2(OH)2 (−60 kcal/mol). Formation of the CH3OOH···F- complex, with randomization of its internal energy, is important, and this complex dissociates via the ECO2 mechanism. Trajectories which form HF + CH3OO- are nonstatistical events and, for the 4 ps direct dynamics simulation, are not mediated by the CH3OOH···F- complex. Dissociation of this complex to form HF + CH3OO- may occur on longer time scales.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja0717360