An ab initio investigation on transition states and reactivity of chloroethane with OH radical

Abstract

The reaction C 2 H 5 Clϩ•OH→C 2 H 5 Cl•ϩH 2 O ͑␣ and ␤ abstraction͒ has been investigated by ab initio molecular orbital theory with several basis sets and levels of correlation. Optimized geometries and harmonic vibrational frequencies have been calculated for all reactants, transition states, and products at the ͑U͒HF/6-31G(d,p) and ͑U͒MP2/6-31G(d,p) levels of theory. The correlation energy is found to play an important role in determining the barrier heights and reaction enthalpies as well as the geometry and the vibrational frequencies of the transition states. A pseudocyclic transition state is found to be favorable to the ␤-abstraction reaction since the participation of the chlorine substituent reduces the barrier height by 0.95 kcal/mol, through a relatively large inductive through-space effect. The best results for the barrier heights and reaction enthalpies have been obtained using the second-order Mo "ller-Plesset perturbation theory with spin projection employing the 6-311ϩG(2d,p) basis set. A satisfactory agreement is found with available experimental values.

Modeling lifetime and degradability of organic compounds in air, soil, and water systems (IUPAC Technical Report)

“…The tremendously fast developments in computing technology, hardware, and software have enabled the calculation of the energy profiles of gas-phase reactions with OH radicals. The abstraction of hydrogen atoms by hydroxyl radicals, as well as its addition to the double bonds, have been a subject of theoretical investigations with semiempirical [38][39][40] and accurate ab initio [41][42][43][44][45][46][47][48][49][50][51][52] MO calculations during the last decade. The early efforts have focused on studying structural and energetic properties of reactants, products, and transition-state structures of hydroxyl radical reactions with small hydrocarbons and their halogenated derivatives [41][42][43][48][49][50][51]53].…”

Development of Predictive Models of the Kinetics of a Hydrogen Abstraction Reaction Combining Quantum-Mechanical Calculations and Experimental Data

“…For the hydrogen abstraction reactions between the hydroxyl radical and alkanes, a number of computational studies has been presented in the literature [19][20][21][22][23][24][25][26][27][28][29][30] ranging from the basic framework of Hartree-Fock (HF) theory to very expensive compound methods, such as the popular G2 method, 31 and the coupled-cluster method with triple-excitation terms, CCSD(T). 32,33 Despite the large variety of computational methods tested, there is no clear consensus on which one is the most appropriate method to study the energetics for this class of reactions, as contradictory examples of their performance may be found.…”

Using Variable and Fixed Topological Indices for the Prediction of Reaction Rate Constants of Volatile Unsaturated Hydrocarbons with OH Radicals

“…Recently, several quantitative structure property relationship (QSPR) prediction models were developed to predict reaction rate constants for the reaction of OH radicals with different organic species. These models estimated reaction rate constants based on empirical fragment contribution technique [4][5][6], bond dissociation energy [7][8][9], NMR chemical shift data [10], ionization potentials [11][12][13], molecular orbital calculations [14][15][16][17][18][19][20][21] and various structural descriptors [22][23][24][25][26][27]. A comprehensive overview [28] of these method and their partial evaluations were recently published [29].…”