Hydroformylation of eugenol, a naturally occurring allylbenzene, was successfully carried out with a rhodium-functionalized MOF (MOF-808-Rh0.15) as a heterogeneous catalyst, providing the corresponding aldehydes chemoselectively. Optimization of key reaction parameters, including rotation speed, temperature, pressure, reaction time, and catalyst mol %, enabled full conversion with 99% chemoselectivity toward aldehyde products. Ultralow Rh loading (0.15 wt %) and the large pores that facilitate mass transport of bulky substrates, combined with an extremely low Rh-to-substrate mol % of 0.002–0.004, led to high turnover numbers (40,068) and turnover frequency (17,363 h–1) for the three-phase reaction, thus highlighting the rational design of a MOF catalyst as well as that of the hydroformylation protocol. Furthermore, this catalytic system was efficiently extended to other allyl benzene derivatives, such as estragole, methyl eugenol, anethole, allyl benzene, and 4-allyl toluene, the majority of which also occur naturally, demonstrating its versatility. Importantly, recyclability studies revealed negligible loss of activity, underscoring the robustness of the system. The combination of high efficiency, broad substrate scope, catalyst recyclability, and reliance on renewable feedstocks highlights this methodology as a sustainable and economically viable route for hydroformylation.
Prajapati et al. (Fri,) studied this question.