Mechanistic aspects of Friedel-Crafts alkylation over FeY zeolite

Abstract

Foram estudados os efeitos da razão molar aromático/cloreto de alquila, adição de base, solvente e agente alquilante, na alquilação do etilbenzeno catalisada pela zeólita FeY. Ficou caracterizada a alquilação ocorrendo no interior dos poros da zeólita, uma vez que ela é pouco afetada pela razão molar dos reagentes. A adição de bases e solventes oxigenados, capazes de complexar com o sítio ativo, inibe a reação. Foi proposto um mecanismo envolvendo transferência de um elétron entre as espécies de ferro ativas e o cloreto de alquila, para explicar os resultados.The effect of aromatic/alkylchloride molar ratio, base addition, solvent and alkylating agent on the ethylbenzene alkylation over FeY zeolite was investigated. It was shown that alkylation occurs inside the pores and it is little affected by the reactants molar ratio. On the other hand, addition of bases or oxygenated compounds, capable of complexing with the active site, blocks the reaction. A mechanism involving single electron transfer between the active iron species and the alkylchloride was propose to account for the results.

The tert-butyl cation on zeolite Y: A theoretical and experimental study

“…This strategy has shown to be efficient to characterize the different butoxides over zeolite Y by infrared spectroscopy [18], under controlled conditions. We have also employed this procedure in Friedel-Crafts reactions [19,20] and isobutane/2-butene alkylation [21].…”

Combined Influence of Fluorinated Solvent and Base in Friedel−Crafts Reaction of Toluene and CO2

“…This clearly indicated that the increase in the rate of reaction is a function of proton absorption capability of the base. There are few literature reports which ascertain the concept of absorption of HCl by base increasing the rate of reaction …”

“…There are few literature reports which ascertain the concept of absorption of HCl by base increasing the rate of reaction. 28 3.3. Effect of the Fluorinated Solvent.…”

Spectroscopic Evidence for the Involvement of a Radical Intermediate in the Friedel-Crafts Benzylation Using Ion-Exchanged K10 Catalysts

“…Three probable mechanistic interpretations can be found in the literature for benzylation of aromatic hydrocarbons with benzyl chloride on solid acid based supported metal catalysts, without any direct (preparative or spectroscopic) experimental verification: a simple radical step [12][13][14][15][16][17] -see Scheme 1; the presence of a benzyl chloride radical cation [4,[18][19][20][21][22][23][24][25]] -see Scheme 2; or the presence of a benzyl radical cation [26][27][28] as intermediate -see Scheme 3. In some cases the same authors have different suggestions for similar catalytic systems.…”