Onium salts, supported phase catalysis

With a view to producing catalysts that can easily be removed from reaction products, typical phase-transfer catalysts such as onium salts, crown ethers, and cryptands have been immobilized on polymer supports. The use of such catalysts in liquid-liquid and liquid-solid two-phase systems has been described as triphase catalysis (Regen, 1975, 1977). Cinquini et al. (1976) have compared the activities of catalysts consisting of ligands bound to chloromethylated polystyrene cross-linked with 2 or 4% divinylbenzene and having different densities of catalytic sites ([126], [127], [ 132]—[ 135]) in the... 

The majority of research on catalysis by anion-exchange resins is devoted to the use of resins in interfacial catalysis reactions [38-43]. In this connection, quaternary ammonium or phosphonium, onium salts have been commonly obtained [44]. Crown-ethers, cryptands and linear polyesters supported on polymers also catalyze similar reactions dealing with the interfacial transfer of reagents. In the simplest case, the mechanism of interfacial catalysis represents a substitution reaction of Sf 2 type typical for the interaction of the nucleophile, T , present in the aqueous solution with the alkyl halogenide, RX, in the organic phase ... 

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