Synthesis and Polymerization of Novel Quinone Methide Ketals

Summary Novel quinone methide ketals, 8- 1'-cyano-1'-(ethoxycarbonyl)methylene]-l,4-dioxaspiro4.5]deca-6,9-diene (1a) and 8-(1',l'-dicyanomethy1ene)-1,4-dioxaspiro4.5]deca-6,9-diene (1b), were synthesized, and their polymerization behavior was investigated. Polymerizations of 1a and 1b initiated with BPO and BF₃·Et₂O gave corresponding novel ring-opening polymers, but no polymerization with BuLi. Copolymerization of 1a with St in the presence of AIBN at 60 °C gave the monomer reactivity ratios r₁(1a) = 0.50 ± 0.1 and r₂(St) = 0.1 ± 0.02, and Q and e values of 1a were 2.46 and +0.93, indicating that 1a is a highly conjugative, electron-accepting monomer. Homopolymers of 1a and 1b had better thermal stability than that of 7-cyano-7-(ethoxycarbonyl)- 1,4-benzoquinone methide. Received 23 January 2003/Revised version 28 February 2003/ Accepted 1 March 2003 Correspondence to Takahito Itoh