Yttrium-catalyzedcis-1,4-Selective Polymerization of 2-(4-Halophenyl)-1,3-Butadienes and Their Copolymerization with Isoprene

Polymerization of 2-(4-halophenyl)-1,3-butadiene (2-XPB) and their copolymerization with isoprene using a yttrium catalyst have been examined. The beta-diketiminato yttrium bis(alkyl) complex(1)activated by [Ph3C][B(C6F5)(4)] and Al(i)Bu(3)shows highcis-1,4-selectivity (>98%) for the polymerization of 2-XPB (2-XPB = 2-FPB, 2-ClPB and 2-BrPB) to afford halogenated plastic poly(dienes) with glass transition temperatures of 30-55 degrees C. Moreover, the copolymerization of 2-XPB with isoprene (IP) has also been achieved by this catalyst, and the insertion ratios of 2-XPB can be facilely tuned in a full range of 0%-100% simply by changing the 2-XPB-to-IP ratio. Quantitative hydrogenation ofcis-1,4-poly(2-XPB) results in perfect alternating ethylene-halostyrene copolymers, and an alternating copolymer of 4-vinylbenzoic acid with ethylene is obtained by a consecutive reaction of ethylene-4-bromostyrene copolymer with(n)BuLi, CO(2)and HCl.