The chemistry of clay‐organic reactions is a relatively young scientific discipline, dating from the early 1940s. Its development followed closely on the general acceptance of the crystallinity, and the elucidation of the structures, of the main groups of clay minerals (Grim, 1968). Because of their importance to agriculture and industry, clay‐organic systems have since then, attracted the attention of workers from different backgrounds and with diverse interests (Greenland, 1965; Mortland, 1970; Theng, 1974, 1979; MacEwan and Wilson, 1980; Burchill et al., 1981; Lagaly, 1984; Rausell‐Colom and Serratosa, 1986). Over recent years the focus of attention has shifted from studying the clay‐organic interaction to exploring the potential of clays as catalysts for organic conversions and syntheses (Theng, 1982a; Thomas, 1982; Pinnavaia, 1983; Adams, 1987; Laszlo, 1987; Zielke et al., 1989). Organic catalysis over clays, however, will not be discussed here.