Equivalent study was undertaken to identify the optimal p-cresol/GII ratio to achieve the highest selectivity towards cross-metathesis product since the addition of p-cresol to GII has made the intended cross-metathesis product 3 prevailed over self-metathesis 4 and to evaluate the impact of reactant mole fraction (X_{Trans-anethole} » 0.09, 0.17, 0.22, 0.33, 0.50, 0.67, 0.83, 0.91) on the product distribution in the p-cresol/GII catalyzed reaction between 2-ethylhexyl acrylate 1 and trans-1-methoxy-4-(1-propenyl)benzene 2. ¹H NMR spectroscopy was employed to monitor the formation and distribution of SM (3), and CM (5) in CD₂Cl₂ at different temperatures (25 ^°C, and 35 ^°C) in the presence of p-cresol/GII (100: 1 ratio and X₁ = 0.33) for 722 mins. Time traces confirmed that an induction period occurred at both temperatures and the elevated temperature has a profound effect on the selectivity of the p-cresol/GII catalyst because at 35 ^°C, the induction period is only 4 mins as compared to the ca. 40 mins at 25 ^°C. The rate for the CM reaction (k'_obs = 0.68 min^-1) is ca. 1.5 times that of SM reaction k'_obs = 0.41 min^-1 at 25 ^°C.

Elizabeth Erasmus

Appearances