Friedel-Crafts alkylations on nanoscopic inorganic fluorides

The catalytic potential of nanoscopic MFx (M = Mg, Al; x = 2, 3) has been investigated using batch Friedel-Crafts alkylation of aromatic compounds, including benzene, ethylbenzene, trimethylhydroquinone (TMHQ), and menadiol (MDL), with isophytol and benzyl alcohol. The conversion of isophytol was 100% in the reactions with trimethylhydroquinone (TMHQ), menadiol (MDL) and benzene while the highest selectivity in alkylated compounds was achieved with TMHQ (>99%). The different reaction rates of the alkylation reactions are due to the different nucleophylicities of the substrates, and therefore, due to their ability to delocalize the positive charge in the Wheland intermediate by inductive and resonance effects. The conversions of benzyl alcohol varied between 10 and 84% as a function of the catalyst nature and reaction conditions while the highest selectivity to monobenzyl derived compounds (25%) was achieved with ethylbenzene. The formation of high amounts of dibenzyl ether was also observed, indicating the presence of high amounts of Bronsted acid sites in this type of catalysts. (C) 2010 Elsevier B.V. All rights reserved.