Alkylation of dihydroxybenzenes and anisole with methyl-tert-butyl ether (MTBE) over solid acid catalysts

Abstract

The synthesis of tert-butylated dihydroxy and alkoxy benzenes from catechol, resorcinol and anisole, with MTBE has been carried out in presence of variety of solid acid catalysts. The current work dealt with the efficacy of various solid acid catalysts in the alkylation of substituted benzenes and MTBE. MTBE is a better tert-butylating agent than isobutylene and tert-butyl alcohol. 20% w/w dodecatungstophosphoric acid (DTP) supported on K10 montmorillonite clay was found to be very effective in comparison with other solid acid catalysts used. A complete theoretical and experimental analysis is presented for the model studies of catechol/anisole with MTBE. The reaction follows a typical second order kinetics at a fixed catalyst loading, with weak adsorption of both the species. The energy of activation for catechol alkylation was found to be 8.86 kcal mol⁻¹, which was low and suggested that intraparticle diffusional resistance would set in for larger particle size. For anisole alkylation the energy of activation was 17.36 kcal mol⁻¹ indicating that the reaction is intrinsically kinetically controlled.