Organoaluminum catalysts for polymerization reactions. The effect of metal hydroxides on the catalytic activity of the Al(C2H5)3/H2O system

The catalytic activity of the system Al(C₂H₅)₃/H₂O was investigated. Instead of pure water aqueous solutions of inorganic bases were reacted with Al(C₂H₅)₃ in toluene/diethyl ether media. A uniform soft gel-like product was readily obtained in this reaction (H₂O/Al(C₂H₅)₃ ～ 1.0–1.5) differing from the heterogeneous nature of the product obtained with pure water. The polymerization of acetaldehyde proceeded with higher stereo-regularity in this system Al(C₂H₅)₃/aqueous inorganic base. The polymerization behavior and the stoichiometric reaction between the catalyst and the monomer (ethyl acetate formation) indicate that there seem not to be significant differences in the active species of Al(C₂H₅)₃/aqueous inorganic base and Al(C₂H₅)₃/H₂O systems. Improved stereospecific polymerization in the presence of inorganic bases is discussed with respect to the formation of a cross-linked product in the Al(C₂H₅)₃/H₂O system in the preparation of the catalyst.