Etherification of β-naphthol with alkanols using modified clays and sulfated zirconia

Alkyl 2-naphthyl ethers are an important class of precursors for the manufacture of fine chemicals useful as perfumery and pharmaceutical chemicals. The efficacy of solid acid catalysts such as acid-treated clays (Filtrol-24 and K-10), heteropolyacids (dodecatungstophosphoric acid, dodecatungstosilicic acid, dodecaphosphomolybdic acid), zeolites (X, Y, mordenite, ZSM-5), and sulfated zirconia was tested in the etherification of beta-naphthol with methanol. Among these catalysts, dodecatungstophosphoric acid supported on K-10 clay was found to be the best. The rates of etherification with other aliphatic alcohols over the same catalyst at 150 degrees C were in the following order n-BuOH > 2-PrOH > MeOH > EtOH > n-PrOH. A kinetic model was built for these reactions. The catalyst can be easily recovered and reused without any significant loss in activity.