Scandium-Catalyzed Syndiospecific Chain-Transfer Polymerization of Styrene Using Anisoles as a Chain Transfer Agent

The polymerization of styrene in the presence of various anisole derivatives has been examined by using the half-sandwich scandium diaminobenzyl complex (C 5 Me 4 SiMe 3 )Sc(CH 2 C 6 H 4 NMe 2 - o ) 2 with borate [Ph 3 C][B(C 6 F 5 ) 4 ]. The syndiospecific chain transfer polymerization of styrene proceeded efficiently via the ortho -C–H bond activation of anisoles, affording the corresponding end- ortho -anisyl-functionalized syndiotactic polystyrenes. The molecular weight of the resulting polymers could be controlled in a wide range by changing the styrene/anisole feeding ratio. Propenyl and halogen (F, Cl, Br, and I) substituents on the anisole compounds are compatible with the present catalyst system, thus enabling easy introduction of unsaturated C═C double bond or halogen moieties together with the anisole functionality to the chain end of syndiotactic polystyrene.