A Novel Friedel-Crafts Acylation Reaction of Anisole for Production of 4-Methoxyacetophenone with High Selectivity and Sufficient Reusability of Mordenite Zeolite Catalyst

Abstract

Zeolite catalyzed Friedel-Crafts reactions were examined using acetic anhydride as an acetylating agent and an acetic acid as a solvent. It revealed that the reaction of anisole smoothly occurred quantitatively for 3 h using mordenite zeolite with SiO 2 /Al 2 O 3 = 200, and with SiO 2 /Al 2 O 3 = 110, the increasing of Brønsted acidity allowed to completely react within 2 h. Furthermore the selectivity of 4-methoxyacetophenone (4-MA) among the isomers was found to be quantitative, no by-products and/or isomers were not detectable. With the excellent recyclability and reusability, the mordenite zeolite exhibited at least 30 times quantitatively both conversion of anisole and selectivity of 4-MA. The mordenite catalysts of fresh and the used after 30 times were characterized. This opportunity obviously indicates the sufficient shape selective catalyst of mordenite zeolite and gives a green synthetic tool for heterogeneous acylation reaction.

Nanocrystallite Zeolite BEA for Regioselective and Continuous Acetyl Functionalization of Anisole Using Acetic Anhydride: Catalyst Deactivation Studies

“…Interestingly, all three catalysts were showing high catalytic activity, indicating that even a moderate number of acidic sites are sufficient for attaining the maximum conversion over the strong catalyst surface. The ZB catalysts are extremely regioselective (>98%) toward the facile formation of 4-MAP, and the extent of formation of other side products such as ortho and meta -isomers is much lower due to the catalyst pore topology and pore connectivity . To minimize the deactivation in micropore volume, the feed molar ratio of 2:1 has been chosen to enhance the catalyst stability by using excess anisole that can act as a self-solvent and mitigate the probability of the formation of higher acylated products.…”

“…The ZB catalysts are extremely regioselective (>98%) toward the facile formation of 4-MAP, and the extent of formation of other side products such as ortho and metaisomers is much lower due to the catalyst pore topology and pore connectivity. 2 To minimize the deactivation in micropore volume, the feed molar ratio of 2:1 has been chosen to enhance the catalyst stability by using excess anisole that can act as a self-solvent and mitigate the probability of the formation of higher acylated products. Catalytic activity has been rapidly decreased with increasing TOS in the case of ZB-1 and ZB-3 due to the leaching of aluminum from the catalyst surface by acetic acid, (formed in the reaction) and also the strong retention of the product in the intercrystallite and mesopore region of ZB catalysts due to having higher equilibrium adsorption constant of 4-MAP compared to feedstock molecules.…”

“…Heterogeneous solid acid catalysts were identified as eco-friendly and promising catalysts for Friedel–Crafts acylation reactions because of their tailorable acidity, pore topology, tunable textural properties, high thermal stability, trouble-free handling, easy separation from reaction media, a lower amount of catalyst requirement, and reusability for multiple times after regeneration. Various three-dimensional solid acid catalysts such as mesoporous silica, − heteropolyacids, , H-MFI, H-FAU, H-BEA, − and H-MOR , have been extensively examined for catalytic activity studies on acylation of anisole under various ranges of process parameters in the batch reactor. Among the solid acid catalysts mentioned above, zeolite beta (BEA) is considered as a prominent catalyst for the acylation of anisole because of its divertive strong acidity originating from a structural framework constituted by two polymorphs and interconnecting channels with a high concentration of structural defects, − which provides a higher level of anisole conversion, and also its pore topology oriented toward the regioselective formation of 4-MAP. − Synthesis of organic compounds over solid acid catalysts often suffers from rapid catalytic deactivation because of their strong interaction with oxygenated products, dealumination, and trapping of heavier molecular weight products in micropores/mesopores or on the intercrystalline surfaces because of their diffusion limitation. ,,,− A deactivated catalyst always needs to undergo catalyst regeneration, which triggers an increase in the process economics and yield loss and imposes technical complexities.…”

“…Friedel–Crafts reaction is one of the most promising synthetic tools for the successful incorporation of acyl and alkyl moieties over the benzene ring to produce aromatic ketones and alkyl derivatives of aromatic compounds. − Aromatic ketones/acetophenones are the pivotal intermediates for the production of fine chemicals, drugs, agrochemicals, fragrances, and pharmaceutical industries . Conventionally, homogeneous Lewis acids such as AlCl 3 , BF 3 , and FeCl 3 were used as catalysts to foster the rate of reaction to produce aromatic ketones using activated carboxylic acids (acid chlorides and acid anhydrides) as acylating agents.…”

Synthesis of Novel Biolubricants from Waste Cooking Oil and Cyclic Oxygenates through an Integrated Catalytic Process

“…The Cu/ZSM5-MgO catalyst was removed by filtration while sulfuric acid was neutralized after the hydrotreatment step. The FC acylation of 2-MF takes place on position 5 according to reaction : However, in the case of anisole, the alkylation reaction could take place via both reactions and 5 using anhydrides and carboxylic acids as reactants, respectively: , Both reactions may result in aromatic ketonic products with similar chemical structure. Hence, more detailed reaction studies would be needed to quantify the extent of each reaction.…”