| 18613207 |
Ouchi M, Ito M, Kamemoto S, Sawamoto M: Highly active and removable ruthenium catalysts for transition-metal-catalyzed living radical polymerization: design of ligands and cocatalysts. Chem Asian J. 2008 Sep 1;3(8-9):1358-64.
The systematic search and design of phosphine ligands (PR (3)) and amine cocatalysts resulted in obtaining pentamethyl-cyclopentadienyl (Cp*) ruthenium (II) phosphine complexes [RuCp*Cl (PR (3))(2)], which are highly active and removable catalysts, for transition-metal-catalyzed living radical polymerization of methyl methacrylate (MMA). The catalysts are conveniently prepared in situ from a tetrameric precursor [RuCp*(mu (3)-Cl)](4) and a selected phosphine (PR (3)). The combination of the meta-tolyl phosphine [P (m-Tol)(3)] ligand and a primary diamine cocatalyst [NH (2)(CH (2))(6) NH (2)] provides a highly active catalytic system with precision control of the molecular weight of the polymer. The high activity enables a low catalyst dose and a high turn-over frequency without deteriorating the controllability. A hydrophilic amine cocatalyst (amino alcohol) in place of the diamine, further forms an active and removable catalyst; simple treatment with acidic water gave colorless polymers visually free from metal residues (> 97 % removal; <64 ppm). |
87(1,1,2,2) |