Metal cation-exchanged montmorillonite(M n+ -mont)-catalyzed reductive alkylation of phenol and 1-naphthol with cyclohexanones

Abstract

The alkylation of phenol with cyclohexanone has been investigated in the presence of a variety of metal cation-exchanged montmorillonites (M n+ -monts; M n+ = Zr 4+, Al 3+, Fe 3+, Na +) and montmorillonite K10. Al 3+-mont is revealed to be an effective catalyst for alkylation of phenol with ketones. Al 3+-mont-catalyzed alkylation of phenol with 4-substituted-cyclohexanones produces almost solely trans-(4-alkylcyclohexyl)phenols, which are good starting materials for some liquid crystals. On the other hand, when a similar reaction is carried out with 1-naphthol instead of phenol in chlorobenzene as solvent, the products are tetrahydrobenzonaphthofuran derivatives and 2-(4-alkylcyclohexyl)-1-naphthols, the former being the major and Fe 3+-mont being the most effective catalyst.