Add time:07/18/2019         Source:sciencedirect.com

The acylation of methylfuran has been investigated using Brønsted and Lewis acid zeolite catalysts. The highest reaction rate for acylation on a per gram basis is found on zeolite Beta with high aluminum content (Si/Al = 23) and the highest turnover frequency on a per metal site basis is found on zeolite Beta with low aluminum content (Si/Al = 138). Among Lewis acid zeolites, [Sn]-Beta shows higher turnover frequency than [Hf]-, [Zr]- or [Ti]-Beta. Similar apparent activation energies were found for [Al]-Beta with different Si/Al ratios and a lower apparent activation energy was found for [Sn]-Beta. Electronic structure calculations reveal that on both [Al]- and [Sn]-Beta the most favorable pathway follows the classic addition-elimination aromatic electrophilic substitution mechanism. The calculations also reveal that, on both [Al]- and [Sn]-Beta, the rate of methylfuran acylation is controlled by the dissociation of the COC linkage of the anhydride while hydrogen elimination is the rate-determining step in the acylation of furan. The latter is in complete agreement with measured primary kinetic isotope effects. One remarkable and unexpected finding from our calculations is that the most favorable catalytic pathway in [Sn]-Beta involves Brønsted acid catalysis by the silanol group of the hydrolyzed “open” site and not Lewis acid catalysis by the Sn metal center.

We also recommend Trading Suppliers and Manufacturers of 3-Methylfuran-methyl-D3 (cas 105855-05-8). Pls Click Website Link as below: cas 105855-05-8 suppliers