Reaction Pathways, Thermodynamics, and Kinetics of Cyclopentanone Oxidation Intermediates: A Theoretical Approach.

Despite the promising role of cyclopentanone as a bioderived fuel, thermodynamic and kinetic data are lacking for low temperature oxidation regimes. In this study, calculations at the CBS-QB3 level explore the subsequent reactivity that results from O-addition to 2- and 3-oxo cyclopentyl radicals, including expected reaction classes such as intra-H migration, HO-elimination, cyclic ether formation, and β-scission along with their thermodynamic parameters. Some of the rates are similar to the analogous reactions of cyclopentane, but some other reactions of cyclopentanone are very different.

Thermochemistry and Group Additivity Values for Fused Two-Ring Species and Radicals.

Motivated by a lack of understanding in the chemical mechanisms of alkylaromatic pyrolysis, the thermochemistry of fused two-ring aromatic molecules and radicals was calculated in this work using the CBS-QB3 level of theory. The enthalpies of formation of some fused ring species differ by as much as 13 kcal/mol from previous estimates. New group values were defined to facilitate better thermochemistry estimates in the future and were found to match the CBS-QB3 calculated values with an average deviation of 0.

Kinetics of Intramolecular Phenyl Migration and Fused Ring Formation in Hexylbenzene Radicals.

A combined ab initio/TST study was conducted to study the phenyl migration and fused ring formation of a series of 1-phenyl-hex- x-yl radicals. Phenyl shift proceeds through a two-step mechanism with a ring closure by ipso-cycloaddition, followed by a ring-opening by β-scission leading to x-phenyl-hex-1-yl radical isomers. Both steps involve a spirocyclic transition state connected by a spirocyclic intermediate.

Reactivity of Hydrogen Peroxide with Br and I Atoms.

The reaction mechanisms of Br and I atoms with HO have been investigated using DFT and high-level ab initio calculations. The H-abstraction and OH-abstraction channels were highlighted. The geometries of the stationary points were optimized at the B3LYP/aug-cc-pVTZ level of theory, and the energetics were recalculated with the coupled cluster theory.

A Density Functional Theory and ab Initio Investigation of the Oxidation Reaction of CO by IO Radicals.

To get an insight into the possible reactivity between iodine oxides and CO, a first step was to study the thermochemical properties and kinetic parameters of the reaction between IO and CO using theoretical chemistry tools. All stationary points involved were optimized using the Becke's three-parameter hybrid exchange functional coupled with the Lee-Yang-Parr nonlocal correlation functional (B3LYP) and the Møller-Plesset second-order perturbation theory (MP2). Single-point energy calculations were performed using the coupled cluster theory with the iterative inclusion of singles and doubles and the perturbative estimation for triple excitations (CCSD(T)) and the aug-cc-pVnZ (n = T, Q, and 5) basis sets on geometries previously optimized at the aug-cc-pVTZ level.

State-to-state chemiluminescence in reactions of Mn atoms with S2Cl2.

A combined experimental and time-dependent density functional theory (TDDFT) investigation of the title reaction is presented. Both 'hot' and 'cold' laser-ablated Mn atom beams have been employed to determine the translational excitation functions for production of MnCl*(c(5)Σ(+), d(5)Π, e(5)Δ, e(5)Σ(+), A(7)Π). Analysis in terms of the multiple line-of-centres approach shows that the 'hot' results are dominated by reactions of the second metastable state of Mn, z(8)P(J), all with very low thresholds; while the first metastable state, a(6)D(J), and the ground state, a(6)S, are the precursors in the 'cold' results, all with significant excess barriers.