Ethylene, propylene, and styrene oxides have been polymerized by a range of metal halide catalysts, high molecular weight products being obtained from the two firstnamed. The limited quantitative evidence presented is consistent with the view that these polymerizations proceed by a coordinate propagation mechanism. The effective catalyst for this stage is essentially a metal alkoxide, formed in an initial cationic polymerization in which a small number of monomer units are attached to the metal atom. The propylene oxide polymers generally contain a fraction of crystalline material, but the proportion of this can be reduced practically to zero (with FeCl3 catalysis) by careful exclusion of water.

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H iggivtsm avtd Marshall.4 7 82.Solution: Some Aqects of the Oxidation of Sulphurous Acid.

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