Affiliations: Lab de Química Computacional, Dpto de Química, Facultad de Ciencias y Tecnología, Universidad de Carabobo, Valencia, Venezuela | [x] Centro de Química, Instituto Venezolano de Investigaciones Científicas, IVIC, Caracas, Venezuela | [y] Departamento de Química, Instituto Universitario de Tecnología FRP, Caracas, Venezuela
Correspondence:
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Corresponding author: J.A. Guaregua, Lab de Química Computacional, Dpto de Química, Facultad de Ciencias y Tecnología, Universidad de Carabobo, Apartado 3366, Bárbula 2005, Valencia, Venezuela. E-mail: guaregua@uc.edu.ve.
Abstract: The elimination kinetics study of 2,4-dimethyl-2,4-pentanediol in gas phase at 440°C has been carried out using ab initio MP2 method with 6-31G, 6-31G(d), 6-31G(d,p), 6-31+G(d,p), 6-311G(d) and 6-311G(d,p) basis functions set to explore the possibility of determining a possible concerted process with a six-membered cyclic transition state (TS). Vibrational frequencies analysis was realized in order to confirm the reactant, TS and products structures. The nature of these chemical species is examined in terms of geometrical parameters and of the charge density on the TQAIM analysis. IRC calculations have been performed in order to verify that localized TS structure connect with the corresponding minimum stationary points of the reactant and products. With the aim of corroborating the reaction mechanics postulated by Chuchani et al. [1] in their experimental work, we present a theoretical study in order to calculate the rate constant and the activation parameters. Results from MP2/6-311G(d,p) method was found to be in better agreement with the experimental values of the A-factor Arrhenius, activation energy and, activation enthalpy. However, at these levels of theory, it was not possible to reproduce the experimental values of the rate constant and, activation entropy.
Keywords: 2, 4-dimethyl-2, 4-pentanediol, gas-phase kinetic, rate constant, ab initio MP2 method, transition state structure
