SYNTHESIS AND RADICAL RING-OPENING POLYMERIZATION BEHAVIOR OF VINYLCYCLOPROPANE BEARING 6-MEMBERED CYCLIC ACETAL MOIETY

Synthesis and radical ring-opening polymerization of vinylcyclopropane bearing six-membered cyclic acetal moiety, 1-vinyl-4,8-dioxaspiro[2.5 ]octane (1), were carried out. 1 was prepared by the reaction of 1,1-d ichloro-2-vinylcyclopropane and 1,3-propanediol in DMF in the presence of a base. Radical polymerization of 1 was carried out in the presenc e of an appropriate initiator (3 mol % vs. 1) at 60 and 120 degrees C in degassed sealed ampoules for 20 h. A colorless transparent viscous polymer was obtained by the isolation with preparative HPLC. The struc ture of poly(1) was determined to consist of two 1,5-ring-opened units and a unit bearing no olefinic moiety. The difference of the activati on energies for the ring opening reaction of the cyclopropane ring cal culated by the molecular orbital method could explain the selectivity in the direction of the cleavage of the cyclopropane ring. Acid hydrol ysis of poly(1) afforded the corresponding polyketone in quantitative conversion. (C) 1996 John Wiley & Sons, Inc.