Zirconium‐β Zeolite‐Catalyzed Continuous‐Flow Friedel‐Crafts Acylation Reaction

Abstract

H-β Zeolites, doped with various metal salts, were investigated as heterogeneous catalysts for continuous-flow Friedel-Crafts acylation reactions. It was found that Zr-β zeolites possessed excellent catalyst activity and stability, which enabled its use as a catalyst, up to 5 days, for Friedel-Crafts reactions between various activated arenes and acid anhydrides. Challenging substrates, such as toluene and mxylene, were also successfully applied for the continuousflow process.[a] Dr.

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

“…The authors noticed an enhancement in activity using an excess of toluene and acetic acid as an additive [ 544 ]. A decrease of the zeolite’s stability was also described by Kobayashi et al in 2019 [ 545 ]. The authors noticed a reduction of aluminium content in the zeolite structure, which inevitably brought about a decrease in activity from 94% down to 59% yield ( 640 → 290 ) after 28 hours of usage.…”

New method for the acylation of benzofurans toward the synthesis of 6H-indeno[2,1-b]benzofuran-6-ones and 2,2-bibenzofurans

“…IR spectra were obtained using a PerkinElmer FT/IR spectrometer. 1 H and 13 C NMR spectra were obtained on a Agilent AV400 instrument. High-resolution mass spectra were recorded on a Micromass Q-TOF mass spectrometer.…”

“…10,11 2-Acylbenzofurans can also be obtained by Lewis acid catalyzed acylation of benzofurans using acid anhydrides or acyl chlorides as acylating agents (Scheme 1b). [12][13][14][15] The trifluoroacetic anhydride (TFAA)-mediated acylation 16 using carboxylic acids as the acylating agent have been applied to arenes 17 and heteroarenes including thiophenes, 18 benzothiophenes, 19 pyrroles, 20 and carbazoles. 21 However, to the best of our knowledge, this protocol has never been used with benzofurans, although a single literature precedent with furans as substrates has been reported.…”

Autocatalytic Friedel‐Crafts Acylation of Arenes without Additional Catalyst and Additive

“…However, the use of these catalysts is inconsistent with the criterion of the green and sustainable chemistry due to the difficulties in the separation and regeneration of these homogeneous catalysts. Thus recent efforts have been directed toward the development of solid acid catalysts, e. g. nanocrystalline ZSM‐5, [4] nanosized iron carbide‐encapsulated N ‐doped porous carbons, [5] iron‐based nanoparticles embedded in a graphitic layer of carbon architectures, [6] Fly ash‐based geopolymers, [7] zirconium‐beta Zeolite, [8] high silica mordenite zeolite, [9] silicotungstic acid modified ZIF‐8 [10] . Very recently, several interesting methods for Friedel‐Crafts benzylation reactions have been reported.…”