20th International CODATA Conference (Times New Roman, 11pt)
Session: Computational informatics: integrating data science with materials modeling

Estimation of Solvent Effects For Complexing Reaction of Propylene and Nickel Dithiolene

Qing-Zhen Han^{1, 2}, Yue-Hong Zhao¹ and Hao Wen¹

¹Multi-Phase Reaction Laboratory, Institute of Process Engineering, Chinese Academy of Sciences, P.O. Box 353, Beijing 100080, P. R. China

²Graduate University of Chinese Academy of Sciences, P.O. Box 4588, Beijing 100049, P. R. China

The formation of olefin complexes is of potential importance in the separation of olefins. The solvents will affect the activation energies, and hence the rates and equilibrium constants of the complexing reactions, which performance should be well estimated for the purpose of industrial practice. The solvent effects on the complexing reaction of propylene and nickel dithiolene Ni(S₂C₂H₂)₂ + C₂H₄=CH₂ ® Ni(S₂C₂H₂)₂×C₂H₄=CH₂ are studied in this work by using B3LYP method and Onsager model. Complete optimizations of all the stagnation points are performed in benzene, toluene, tetrahydrofuran, dichloromethane, 1,2-dichloroethane, acetone, ethanol, methanol, 1,2,3-propanetriol, dimethylsulfoxide and water, respectively. The reaction of complexing nickel dithiolene with propylene is a two-step process:

The activation energy of the step-I is higher than that of step-II, indicating that the step-I is the rate-determining step. The solvents make slight changes in the geometries of the reactants, transition states, intermediates, and products. However, the activation energies of step-I (or step-II) will exponentially decrease from 125.0 to 113.0 kJ×mol^-1 (or from 101.8 to 83.43 kJ×mol^-1) when the dielectric constants of solvents increase from 1.00 to 78.39, while the reaction rates of step-I (or step-II) will exponentially increase from 0.767´10^-9 to 96.2´10^-9 s^-1 (or from 0.550 to 1.04 s^-1), and the equilibrium constants will rapidly increase from 0.1863 to 126.4 l×mol^-1. Also, the sharp variations of activation energies, rate constants, and equilibrium constants will appear when the value of the dielectric constant is lied between 1.00 and 20.70, while these variations will become mildly when the dielectric constant of solvents is larger than 20.70. All of these results demonstrate that the complexing reaction of propylene and nickel dithiolene will become much easier and faster to occur in polar solvents. The relationship between the equilibrium constants of the complexing reaction and the dielectric constants of solvents e can be presented mathematically as with the correlation parameters A = -139.3 l·mol^-1, B = 129.1 l·mol^-1 and t = 21.17. This relationship may be seen as a reference for solvent selection in olefin separation practice.

Keywords: Density functional theory; Solvent effects; Performance estimation; Olefins; Nickel dithiolene