The effect of vinylsilane on metathetical degradation and functionalization of 1,4-polybutadiene catalyzed by ruthenium carbene complexes

Abstract

Polybutadiene ( I) containing 91% 1,4-( cis/ trans) units and 9% of 1,2 units, in the presence of vinyltriethoxysilane and ruthenium catalysts Cl 2(PCy 3) 2Ru=CHPh ( II) and [RuCl 2( p-cymene)] 2/N 2CHSiMe 3/PCy 3 ( III) at 60°C and at room temperature undergoes partial degradation and functionalization. At a ratio [vinylsilane]/[total >CC< of ( I)]=0.1, the reaction leads to a limited (compared to ethylene as a substrate) degradation and metathetical conversion of 1,4-polybutadiene (particularly cis-CHCH units) with vinylsilane yielding silylated unsaturated oligomers. At a ratio [vinylsilane]/[total >CC< of ( I)]=1, a cross-metathesis of 1,2 >CC< groups of ( I) with vinylsilane predominated over the degradation/cross-metathesis of 1,4-polybutadiene.