Ally in our laboratory working with the identical experimental technique, exactly the same reference reaction and performed inside the similar temperature range [22, 32, 38]. In addition to that, the reactions of entirely deuterated reactants CD3 X Cl ! CD2 X DCl; were simultaneously studied below precisely the same experimental circumstances. The obtained final results are then precious reference data for the theoretical comparative kinetic analysisputational details The halogenated alkanes were studied theoretically making use of quantum mechanical ab initio methods at a variety of levels of theory. Benefits of those calculations performed to get a wide class of organic compounds show that the G2 technique [45] reproduces effectively the structural parameters and molecular properties of a wide group of organic compounds. The dependable values in the thermochemical properties and vibrational frequencies have already been obtained applying G2 methodology for perhalogenated methanols, methyl hypohalites, halogenated alkyl and alkoxy radicals [466]. The G2 system was also effectively utilized within the theoretical description in the kinetics and mechanism of the hydrogen abstraction from methanol by halogen atoms [579].PhIP Thus, we decided to make use of this degree of theory in our investigations.Capecitabine All quantum mechanical ab initio calculations have been carried out making use of the Gaussian 09 program [60] package.PMID:23935843 The geometries of all stationary point structures with the possible energy surface had been totally optimized at both the SCF and MP2 levels with the 6-31G(d) basis set. Relative total energies were examined applying G2 methodology [45]. Thiswhere X 0 F, Cl and Br. A single expects that the mechanism with the reaction (1) is complicated and H-abstraction proceeds through the formation of intermediate complexes. The attainable competitive reaction channels connected using the abstraction of halogen X from the CH3 X molecule, along with the formation of XCl merchandise are probably associated with higher activation energies and proceed very slowly. Any trace of XCl products was not found within the experimental research, which was the grounds to omit the halogen abstraction within the mechanism on the reactions CH3X + Cl. Our theoretical evaluation with the reaction systems concerns ab initio calculations applying molecular orbital theory in an effort to locate and characterize the characteristic points with the prospective energy surface. The main interest of our study is focused on the doable influence from the formed molecular complexes on the reaction mechanism. The theoretical process applied for the description of your reaction kineticsJ Mol Model (2013) 19:1489approach requires some further calculations at the MP4/ 6-311G(d,p), MP4/6-311+G(d,p), MP4/6-311G(2df,p), MP2/6-311+G(3df,2p), and QCISD(T)/6-311G(d,p) levels using the MP2/6-31G(d) optimized geometry as a reference to get improved energy values. The price constants of the reactions studied had been analyzed in terms of traditional transition-state theory (TST) [61, 62]. The thermochemical formulation of TST leads to the price continuous, kTST, offered by kTST six kB T S H 6exp exp ; h R RT where denotes a symmetry aspect related to reaction path degeneracy, kB and h are the Boltzmann and Planck constants, respectively, S is definitely the activation entropy, and H the activation enthalpy for the reaction under investigation. The vibrational and rotational contributions for the thermodynamic functions had been derived by the classical harmonicoscillator rigid-rotor approximation (no totally free or internal rotation was considered).Results and discussion The molecular arrang.
