Polymerization of alkylene oxides by dialkylzinc–lewis base systems

Dialkylzinc–Lewis base systems are found to be active catalysts for the polymerization of alkylene oxides. The diethylzinc–dimethyl sulfoxide system is especially effective in the preparation of high polymers of ethylene oxide and propylene oxide. Diethylzine does not react with dimethyl sulfoxide, but there is strong association between the compounds. The proton magnetic resonance spectrum of a poly(ethylene oxide) prepared by the catalyst system suggests that the n‐butoxyl group is attached to the end of the polymer chain. Polymerization of ethylene oxide seems to be initiated by the ethyl–zinc bond. The active species of the system seems to be diethylzinc coordinated with dimethyl sulfoxide. The efficiency of the catalyst system for the formation of high molecular weight polymer is 10−1−10−2. The other part of the catalyst is responsible for the formation of low polymers.