ESTIMATION OF SOLVENT EFFECTS FOR THE COMPLEXING REACTION OF PROPYLENE AND NICKEL DITHILENE
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 are studied in this work, using density functional theory with B3LYP and Onsager model in Gaussian03 progress. Optimizations of all the stagnation points are performed in benzene, toluene, tetrahydrofuran, dichloromethane, 1,2-dichIoroethane, acetone, ethanol, methanot, 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 first step is higher than that of the second, indicating that the first step is the rate-determining step. The solvents make slight changes in the geometries of the reactants, transition states, intermediates and products. However, the corresponding molecular dipole moment becomes large with increase of the solvent polarity, which is beneficial to accelerate the reaction. Furthermore, the activation energies of the first (or second) step 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 the first (or second) step will exponentially increase from 14.45 to 1805 1·mol-1·s-1 (or from 3.771×1023 to 6.795×1023 s-1), and the equilibrium constants will rapidly increase from 0.5066 to 343.4. The sharp variations of activation energies, rate constants, and equilibrium constants will appear when the value of the dielectric constant of solvents is lied between 1 and approximately 20, while these variations will become mildly when the dielectric constant of solvents is larger than 20. AH 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 Keq of the reaction and the dielectric constants of solvents can be presented mathematically as Keq =A·xp(-e/t)+B with correlation parameters A = -378.4, B =350.7 and t = 21.17. This relationship may be seen as a reference for solvent selection in olefin separation practice.
Density functional theory Solvent effects Performance estimation Olefins Nickel dithiolene
Qing-Zhen Han Yue-Hong Zhao Hao Wen
Multi-phase Reaction Laboratory, Institute of Process Engineering, Chinese Academy of Sciences,P.O. Multi-phase Reaction Laboratory, Institute of Process Engineering, Chinese Academy of Sciences,P.O.
国际会议
杭州
英文
246-259
2007-04-01（万方平台首次上网日期，不代表论文的发表时间）