Polymeric analogues of dipolar aprotic solvents as phase transfer catalysts

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Abstract
Soluble polymers containing dipolar aprotic solvent moieties such as dimethyl sulfoxide, sulfolane, N,N-dimethylformamide, N,N-dimethyl- acetamide, N-methylpyrrolidone, tetramethylurea and their analogues were prepared by free-radical polymerization and copolymerization of correspon- ding monomers. These polymers serve as effective phase transfer catalysts for several reactions under liquid-liquid two-phase condition. The catalytic activity of the copolymers containing styrene units is generally higher than that of homopolymers. It was found that these polymers extract all alkali metal cations more effectively than their monomeric analogues, and that the extraction ability increases with increasing density of active sites, suggesting their cooperative effect. It is reasonable to assume that the catalytic activity is due to both cation extraction ability of the polymers and the activation of anions caused by desolvation in the hydro- phobic regions of polymers. Insoluble polymers containing dipolar aprotic solvent moiety as well as partially alkylated poly-L-leucine and Nylon-66 also exhibit phase transfer catalytic activity.

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