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|Theoretical study of photochemical hydrogen abstraction by triplet aliphatic carbonyls by using density functional theory
|Firme, Caio Lima
Garden, Simon John
Lucas, Nanci Câmara de
Nicodem, David Ernest
Corrêa, Rodrigo José
|Hydrogen abstraction;Carbonyls;Oxygen;Hydrogen;Chemical reactions
|American Chemical Society
|FIRME, Caio Lima; GARDEN, Simon John; LUCAS, Nanci Câmara de; NICODEM, David Ernest; CORRÊA, Rodrigo José. Theoretical study of photochemical hydrogen abstraction by triplet aliphatic carbonyls by using density functional theory. The Journal Of Physical Chemistry A, [s. l.], v. 117, n. 2, p. 439-450, 18 dez. 2012. ISSN 1520-5215 versão online. DOI https://doi.org/10.1021/jp307505e. Disponível em: https://pubs.acs.org/doi/10.1021/jp307505e. Acesso em: 09 jun. 2020.
|The density functional theory (DFT) and quantum theory of atoms in molecules (QTAIM) have been used to study the lowest lying spin states of the photochemical hydrogen abstraction reaction by formaldehyde, acetaldehyde, and acetone in the presence of different hydrogen donors: propane, 2-propanol, and methylamine. Calculations of all the critical points on the PES of these reactions were performed at uB3LYP/6-311++G(d,p). Methylamine is the best hydrogen donor, in thermodynamic and kinetic terms, followed by 2-propanol and finally propane. Secondary C–H hydrogen abstraction in 2-propanol and C–H abstraction in methylamine is thermodynamically and kinetically favored with respect to hydrogen abstraction from the OH and NH functional groups. Charge transfer takes place before the transition state when methylamine is the hydrogen donor, and for other hydrogen donors, charge transfer begins only in the transition state. The extent of the charge transfer in the transition states corresponds to about 50% of the total change in electron density of the oxygen atom of the T1 carbonyl compounds during the course of the hydrogen abstraction reactions. The effect of solvent was investigated using the continuum solvation model for the reaction of triplet acetaldehyde in acetonitrile, which resulted in a barrierless transition state for hydrogen abstraction from methylamine.
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