Unimolecular HBr and HF Elimination Reactions of Vibrationally Excited CHCHBr and CDCHFBr: Identification of the 1,1-HBr Elimination Reaction from CDCHFBr and Search for the CD(F)C:HBr Adduct.

Chemical activation experiments and computational methods have been used to study the unimolecular reactions of CHCHBr and CDCHFBr with 90 and 93 kcal mol of vibrational energy, respectively. The four-centered elimination reactions of HBr and DBr are the dominant reactions; however, 2,1-DF, 1,1-HBr, and 1,1-HF reactions are also observed from CDCHFBr. The main focus was to search for the role of the CD(F)C:HBr adduct in the 1,1-HBr elimination for comparison with carbene adducts in 1,1-HX(Y) elimination from RCHXY (X,Y = Cl and F) molecules.

Post-transition state dynamics and product energy partitioning following thermal excitation of the F⋯HCHCN transition state: Disagreement with experiment.

Born-Oppenheimer direct dynamics simulations were performed to study atomistic details of the F + CHCN → HF + CHCN H-atom abstraction reaction. The simulation trajectories were calculated with a combined M06-2X/MP2 algorithm utilizing the 6-311++G** basis set. The experiments were performed at 300 K, and assuming the accuracy of transition state theory (TST), the trajectories were initiated at the F⋯HCHCN abstraction TS with a 300 K Boltzmann distribution of energy and directed towards products.

Unimolecular reactions of chemically activated CF2BrCF2CH3 and CF2BrCF2CD3: evidence for 1,2-FBr interchange.

Vibrationally excited CF2BrCF2CH3 and CF2BrCF2CD3 molecules were prepared with 96 kcal mol-1 energy at room temperature by the recombination of CF2BrCF2 and CH3 (CD3) radicals. The observed unimolecular reactions are 1,2-BrF interchange to give CF3CFBrCH3 (CD3) molecules and 2,3-FH (FD) elimination; the rate constants are 2.2 x 10(5) (1.

Use of a single trajectory to study product energy partitioning in unimolecular dissociation: mass effects for halogenated alkanes.

A single trajectory (ST) direct dynamics approach is compared with quasiclassical trajectory (QCT) direct dynamics calculations for determining product energy partitioning in unimolecular dissociation. Three comparisons are made by simulating C(2)H(5)F-->HF + C(2)H(4) product energy partitioning for the MP26-31G(*) and MP26-311 + + G(**) potential energy surfaces (PESs) and using the MP26-31G(*) PES for C(2)H(5)F dissociation as a model to simulate CHCl(2)CCl(3)-->HCl + C(2)Cl(4) dissociation and its product energy partitioning. The trajectories are initiated at the transition state with fixed energy in reaction-coordinate translation E(t) (double dagger).

Comparison of levels of electronic structure theory in direct dynamics simulations of C2H5F --> HF + C2H4 product energy partitioning.

Direct dynamics simulations at the MP2/6-311++G** level of theory were performed to study C(2)H(5)F --> HF + C(2)H(4) product energy partitioning. The simulation results are compared with experiment and a previous MP2/6-31G* simulation. The current simulation with the larger basis set releases more energy to HF vibration and less to HF + C(2)H(4) relative translation as compared to the previous simulation with the 6-31G* basis set.