Synthesis and radical ring-opening polymerization behavior of vinylcyclopropanes bearing cyclic thioacetal moieties

The synthesis and radical ring-opening polymerizations of vinylcyclopropanes bearing six-, seven-, and eight-membered cyclic thioacetal moieties, 1-vinyl-4,8-dithiospiro[2.5]octane (4), 1-vinyl-4,9-dithiospiro[2.6]nonane (5), and 1-vinyl-4,10-dithiospiro[2.7]decane (6) were carried out. Monomers 4-6 were prepared by reactions of 1,1-dichloro-2-vinylcyclopropane and corresponding dithiols in N,N-dimethylformamide (DMF) in the presence of a base. Radical polymerizations of 4, 5, and 6 were carried out at 60, 80, and 120 degrees C for 20 h in the presence of an appropriate initiator (3 mol% vs. monomer) to obtain polymers with M-n 600-3100, mainly consisting of a 1,5-ring-opened unit and a unit with no olefinic moiety.