SYNTHESIS AND PHASE-TRANSFER CATALYTIC ACTIVITY OF NOVEL CHIRAL CROWN-ETHERS IMMOBILIZED ONTO POLYSTYRENE SUPPORTS

Polymer-supported novel optically active crown ethers were prepared by the reaction of chiral crown ethers derived from L-(+)-tartaric acid and 4-chloromethylated polystyrene resins crosslinked with 2 mol% of d ivinylbenzene. The ring substitution which indicates percentages of fu nctionalized unit of the obtained polymers was in the range of 12-33%. The phase-transfer catalytic activity of the polymer-bound crown ethe rs has been studied on the reaction of 1-halo-octane with NaI or KI un der liquid/liquid/solid tri-phase conditions. The catalyst with 18-cro wn-6 unit exhibited higher activity than the catalyst with 15-crown-5 unit. The activity of the catalyst with 18-crown-6 moiety for the reac tion of 1-chloro-octane with KI was independent of catalyst particle s ize and increased with decreasing the degree of ring substitution, and the reaction rates were considered to be controlled only by the intri nsic reactivity at active site. On the other hand, the activity for th e reaction of 1-bromo-octane with KI were dependent on catalyst partic le size and exhibited maximum near 15-20% ring substitution, and the r eaction rates were concluded to be limited by both the intrinsic react ivity and the intraparticle diffusion of reactants. The recovered cata lyst could be reused repeatedly without a decrease in the activity. (C ) 1998 Elsevier Science B.V. All rights reserved.