Determination of Kinetic Constants for Titanium-based Ethylene Trimerization Catalysis

For two titanium-based ethylene trimerization catalysts, [(Me₃SiC₅H₃CMe₂C₆H₃Me₂)TiCl₃] (1) and [(Me₃SiC₅H₃C(CH₂)₅C₆H₃Me₂)TiCl₃] (2), the entropies and enthalpies of activation for the ethylene trimerization reaction (k₁) as well as the catalyst deactivation reaction (k_d) have been determined. Using a combination of, on the one hand, experimental pressure and temperature data and, on the other hand, vapor−liquid equilibrium calculations, the 1-hexene concentration as a function of time was estimated and these data were fitted to a kinetic model to obtain the thermodynamic data. A best fit was obtained for a combination of a propagation reaction that is first order in the ethylene concentration and a catalyst deactivation reaction that is second order in the catalyst concentration. The measured entropies and enthalpies of activation are in good agreement with the previously reported calculated ones.