Synthesis and polymerizations of methyl 3,3‐difluorocyclobutene‐1‐carboxylate and methyl 3,3,4,4‐tetrafluorocyclobutene‐1‐carboxylate

Abstract

AbstractTwo new monomers, methyl 3,3‐difluorocyclobutene‐1‐carboxylate (MDFC) and methyl 3,3,4,4‐tetrafluorocyclobutene‐1‐carboxylate (MTFC), were synthesized. Under free radical conditions, MDFC gave homopolymer; MTFC did not. Copolymerizations of these monomers showed them to behave as very electron‐deficient monomers, MTFC more so than MDFC. MDFC copolymerized with various vinyl ethers and styrenes to give high yields of almost 1:1 copolymers. Acrylonitrile copolymerized in lower yield with less incorporation of MDFC; trimethylethylenetricarboxylate did not copolymerize. Bicyclobutane‐1‐carbonitrile copolymerized well. MTFC copolymerized with the very electron‐rich monomers t‐butyl vinyl ether and p‐methoxystyrene, leading to alternating and nearly alternating copolymers, respectively, and even styrene tended to give almost 1:1 copolymers. Acrylonitrile gave only polyacrylonitrile, and trimethylethylenetricarboxylate did not react with MTFC under free radical conditions. The reaction of MTFC with the electron‐rich monomers t‐butyl vinyl ether and p‐methoxystyrene occurred spontaneously via charge transfer complexes. Thermally, the copolymers were rather stable, those of MTFC more so than those of MDFC.