Types of Supported Reagents

Whereas the motivation behind Fetizon s original work and much of the early research on supported reagents was directed towards stoichiometric reagents such as silver carbonate (so that at best only the support could be recovered unchanged), much of the more recent published work has dealt with genuinely catalytic materials whereby the entire supported reagent can, at least in principle, be recovered unchanged from the reaction. The main emphasis here will be on catalytic materials. 

Silica gels (commercial) Widely available and inexpensive high surface area, mesoporous and normally broad pore size distribution surfaces are heavily hydroxylated and easily functionalised (halogenation, silylation) 

Structured silicas (synthetic) MCMs and HMS materials are mesoporous prepared using sol-gel methods using onium or amine templates, very high surface areas ( 1000 m2 g ) and narrow pore size distribution but little long-range order often less hydrophilic than normal silicas 

Montmorillonites (natural and synthetic) Natural clays can have swelling structure giving microporosity pillared clays have larger pores add-treated clays are partially mesoporous (and may change with agdng) 

Altuninas Moderate surface areas available in addic, basic and neutral forms 

---