SYNTHESIS AND RADICAL POLYMERIZATION OF SPIRO ORTHOCARBONATES BEARINGEXOMETHYLENE GROUPS

Synthesis and radical polymerization of spiro orthocarbonates (SOCs) b earing exomethylene groups at the alpha to the ether oxygen (1a-1e) we re studied. SOCs 1a-1e were prepared by the successive reactions of di chlorodiphenoxymethane with two different diols followed by dehydrochl orination. Radical polymerization of the SOCs was carried out in the p resence of an appropriate initiator (3 mol % versus monomer) at 130 an d 180 degrees C. The obtained polymer insoluble in n-hexane contained both vinyl polymerization unit 13 and double ring-opening polymerizati on unit 14 (ketone-carbonates). The degree of ring-opening followed th e order: 1a < 1b < 1d, 1e. n-Hexane-insoluble polymer was not obtained in the polymerization of 1c. Both steric hindrance of methyl group an d ring size affected the degree of ring-opening. The introduction of m ethyl group into SOC increased the degree of ring-opening (1a < 1b), w hereas the degree of ring-opening of either 1d, consisting of six- and seven-membered rings, and 1e, consisting of two seven-membered rings, was higher than those of 1a and 1b, consisting of five and seven-memb ered rings. From the molecular orbital calculation (PM3, UHF method), it was concluded that if the first single ring-opening occurs, then th e successive second ring-opening takes place more smoothly. The first ring-opening requires more energy than the vinyl polymerization does. (C) 1994 John Wiley & Sons, Inc.