Selective organic synthesis over metal cation-exchanged clay catalyst

Abstract

Results of recent studies conducted by the authors are reviewed on the use, as catalysts, of metal cation-exchanged montmorillonite (M•+-mont), a modified natural clay with a layer structure, and metal cation-exchanged fluor-tetrasilicic mica (M•+-TSM), a synthetic clay with a layer structure, for the following organic synthesis: (1) Friedel-Crafts alkylation of phenol with 4-hydroxybutan-2-one to produce 4-(4-hydroxyphenyl)butan-2-one (raspberry ketone), (2) rearrangement of alkyl phenyl ethers to corresponding alkylphenols, (3) aromatic alkylation of phenol with aldehydes and ketones to produce corresponding gem-bis(hydroxyphenyl)alkanes (bisphenols) and alkylphenols, respectively, (4) a facile and an almost quantitative substrate-selective acetallization, (5) alkane oxidation with aqueous tert-butyl hydroperoxide, (6) Prins reaction of styrenes with aldehydes using clay as a Brönsted acid, and (7) inter-and intra-molecular carbonayl-ene reaction using clay as a Lewis acid in condition similar to that of Prins reaction. In almost all cases, the clay catalysts could be regenerated and reused several times, after filtration, washing and drying.