Experimental, DFT and kinetic study of 1-octene metathesis with Hoveyda-Grubbs second generation precatalyst
Van der Gryp, Percy
Vosloo, Hermanus C.M.
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In this study we report the catalytic performance, reaction engineering kinetics and elucidation of the reaction mechanism using density functional theory (DFT) for the metathesis reaction of 1-octene in the presence of the Hoveyda-Grubbs 2 [RuCl2(CHoOiPrC6H4)(H2IMes)] precatalyst. The study showed that reaction temperature (30-100 °C), 1-octene/precatalyst molar ratio (5000-14,000) and different solvents had a significant effect on the selectivity, activity and turnover number. Turnover numbers as high as 6448 were observed. Two main reactions were observed, namely: metathesis over the entire temperature range and isomerization above 50 °C. The observed experimental product-time distribution data for the complex parallel reaction system was fairly accurately described by four pseudo-first order reaction rates. The effects of temperature (Arrhenius Equation) and precatalyst concentration were incorporated in the observed rate constant. The primary observed activation energy was approximately 24 kcal mol−1, which is in agreement with the DFT computational values for the proposed Hoveyda-Grubbs mechanism.