Alkylation of toluene over basic catalysts - Key requirements for side chain alkylation

In situ infrared spectroscopy was used to study sorption and reaction of to luene and methanol over various basic catalysts (MgO, hydrotalcites, and ba sic zeolites). The size of the metal cations controls the preference of sor bing methanol or toluene; i.e., the larger the metal cation, the higher the preference for toluene. The key requirements for a good catalyst for side- chain alkylation are (i) sufficient base strength to dehydrogenate methanol to formaldehyde, (ii) stabilization of sorbed toluene and polarization of its methyl group, and (iii) balanced sorption stoichiometry of the two reac tants. The formation of the carbon-carbon bond mechanistically resembles an aldol condensation. (C) 1998 Academic Press.