Abstract: | Equimolar reaction of Et2AlOLi and Et2AlCl gave Et2AlOAlEt2. The catalyst behavior for polymerization of acetaldehyde, propylene oxide, and epichlorohydrin was compared with that of the AlEt3–H2O (1:0.5) catalyst system. The thermal disproportionation product of Et2AlOAlEt2 derived from Et2AlOLi–Et2AlCl had the structure, ? (EtAlO)n? , and it showed catalyst behavior quite similar to that of the product obtained by the same treatment of AlEt3–H2O (1:0.5). These ethylaluminum oxides can be regarded as species predominating in AlEt3–H2O (1:0.5) and AlEt3–H2O (1:1), respectively. Stereospecific or high molecular weight polymerizations of these species were investigated. |