Studies On Solid-acid Catalysts For The Friedel-crafts Acylation Of Arenes

Aromatic ketones are a class of important chemicals and widely employed in medicinal, agricultural chemical and coating industries. They are normally manufactured by Friedel-Crafts acylation. However, serious environmental pollution arises from the catalysts used for this reaction. Therefore, a series of efficient solid-acid catalysts were designed and applied for the Friedel-Crafts acylation of arenes in this paper.1、A series of the supports and metal oxides were selected and examined. It was found that Fe₂O₃/HY exhibited excellent catalytic performance in the acylation of m-xylene with benzoyl chloride. Under the optimal conditions, the conversion of benzoyl chloride was 99.5%, the selectivity of 2,4-dimethyl-benzoyl benzophenone was 94.5%. In addition, Fe₂O₃/HY provided a promising catalyst for the acylation of electron-rich arenes with acyl chloride. The characterization results of BET, NH3-TPD and Py-IR indicated that modification of HY zeolite with Fe₂O₃ slightly altered its specific surface area, pore volume and total acidic capacity, but more Lewis acids enhanced the reaction, so Fe₂O₃/HY displayed the excellent catalytic performance on this acylation.2、The mechanism of electrophilic cations generating from various acylating agents was studied. It was found that TPA/TiO₂ presents stronger total acidity, especially Br?nsted acidity, enhances the protonation of acetic anhydride and led to form acyl cation. So this catalyst exhibited excellent performance on the acylations with acetic anhydride as acylating agent. Moreover, due to stronger Lewis acid of FeTPA/TiO₂, it is helpful for benzoyl chloride to form benzoyl cation. Therefore, this catalyst exhibited excellent catalytic performance on the acylations with benzoyl chloride as acylating agent. When the loading of FeTPA was 30wt%, the specific surface area and micropore volume of FeTPA/TiO₂ reached to maximum. So this catalyst exhibited excellent catalytic performance on the acylation of m-xylene with benzoyl chloride. Furthermore, when the calcination temperature of FeTPA/TiO₂ exceeded 300!, the active components would be decomposed and the catalyst deactivation occurred.3、The activated Fe-MIL-101 has strong Lewis acidity and large pore size, which !contribute to the mobility of the substrate and the interaction between unsaturated metal sites and the substrate. Therefore, this catalyst exhibited good catalytic performance on the benzoylation of m-xylene. Under the optimal conditions, the conversion of benzoyl chloride was 99.43% and the selectivity of product was 94.58%. Moreover, Fe-MIL-101 was only suitable for the acylation with acyl chloride as the acylating agent.4、Fe₂O₃ was employed for the synthesis of tri-（2,4-dihydroxyphenyl）-1,3,5-triazine from cyanuric chloride and resorcinol in THF with a yield of 56.42%. Furthermore, the UV-1577 intermediate was obtained from benzaldehyde through condensation, dehydration, nucleophilic addition and final cyclization. Therefore, the synthetic route of this target compound was estabilished.