Simple access to alkoxysilyl telechelic polyolefins from ruthenium-catalyzed cross-metathesis depolymerization of polydienes

Abstract

The first functional cross-metathesis (CM) depolymerization of commercial (co)polydienes using a ruthenium catalyst and an acyclic bis(trialkoxysilyl) difunctionalized chain-transfer agent (CTA), [(EtO)3Si(CH2)3NHC(O)OCH2CH]2 (1), towards the synthesis of low viscosity liquid α,ω-bis(trialkoxysilyl) telechelic (co)polydienes is reported. The reactivity of three commercial grades of liquid (co)polydienes (P1–P3, polybutadienes (PBDs) or poly(butadiene-co-isoprene) (P(BD-co-IP))) differing in their end-functionalization, in the amount of 1,2-vinyl and in their dispersity, was explored. Operating conditions for effective production of α,ω-bis(trialkoxysilyl) telechelic PBDs or P(BD-co-IP)s with high chemoselectivity (80–90wt%) and catalytic productivity (non-optimized TON up to 24000) were established. The chemoselectivity of this tandem metathesis reaction was assessed in particular through detailed 2D NMR analyses. An original approach combining the CM depolymerization of PBD with the ring-opening functional metathesis polymerization (ROMP) of a cycloolefin in the presence of CTA 1has also been next implemented affording low viscosity liquid α,ω-bis(trialkoxysilyl) telechelic copolydienes. The viscosity of the (co)polyolefins was investigated by rheological analyses.