Structure and catalytic activity of polymer-supported polyethylene glycol and onium phase transfer catalyst

The gelatinous and macroporous phase-transfer catalysts with multiple activ e centers were synthesized by means of quarterisation. of PEG tertiary amin e and chloromethylated St-DVB copolymer. They were examined as phase-transf er catalysts in the reaction of n-C8H17Br with solid NaI The experimental r esults showed that the reaction rate was first-order with respect to the co ncentration of n-C8H17Br. The effects of catalyst structure on the catalyti c activity were also investigated. The observed reaction rate constant (k(o bsd)) increased as the degree of cross-linking of polymer decreased. Macrop orous catalysts showed a higher activity (2 similar to2.5 times) than that of microporous catalysts with the same degree of cross-linking of polymer, particle size and amount of supported PEG. Molecular weight of PEG also sho wed much influence on k(obsd). As molecular weight of PEG rose properly, th e catalysts showed a higher activity. The results were discussed from the a spect of triphase catalysis reaction mechanism.