CYCLOPOLYMERIZATION OF DIVINYL ETHERS - SYNTHESIS AND THE CATION-BINDING PROPERTY OF POLY(CROWN ETHER)S

Divinyl ethers capable of forming 16-25-membered rings (1a-g) were synthesized and polymerized with SnCl4 in CH2Cl2 at 0-degrees-C. All the polymers obtained were gel-free and did not contain any residual vinylic bonds. In order to confirm the cyclic units, 1,2-bis[2-(2-(vinyloxy)ethoxy)ethoxy]benzene (1a) was reacted with a HI/12 initiator and with MeOH as the terminator. The 19-membered cyclic unimer was isolated, and this result proved that cationic cyclopolymerization of la gave poly(benzo-19-crown-6) (2a) through a head-to-tail addition. Polymer 2a showed the same binding property toward alkali-metal picrates, regardless of its polymerization degrees. The extraction yields for 2a were higher than those for benzo-19-crown-6, and their selectivities were different. For the polymers consisting of 16-25-membered rings, the cation-binding properties were discussed in connection with ring size, shape, and the number and electronic properties of oxygen.