Organic synthesis using clay catalysts: Clays for "green chemistry"

A review. An important family of catalysts that has received significant attention is derived from the soil, the most noteworthy ones being clays and zeolites. Clays are solid acidic catalysts which can function as both Bronsted and Lewis acids in their natural and ion-​exchanged form. Some of the org. reactions that have been conducted using clays as catalysts for reducing environmental pollution are described. Chem. modified clays are considered to be potentially the most cost-​effective nanomaterials, and it is estd. that hundreds of millions of dollars worth of clays will be marketed by 2010. The structure and properties of montmorillonite clay are described. The range of reactions that have been successfully conducted on clay catalysts includes addn., elimination, addn.-​elimination, substitution, rearrangement, Diels-​Alder reactions, and oxidn.-​redn