Copolymerization of propylene oxide and carbon disulfide with diethylzinc–electron-donor catalyst

Copolymerization of propylene oxide with carbon disulfide was studied by using a catalyst consisting of diethylzinc (ZnEt₂) and various electron donors. Tertiary amines, tertiary phosphines, and hexamethylphosphoric triamide were the effective donors for the copolymerization, but ZnEt₂–water, alcohol, and primary or secondary amines having high activities for the homopolymerization of propylene oxide were not effective for the copolymerization of propylene oxide and carbon disulfide. The copolymers obtained were of low molecular weight and had a monomer unit ratio (CS₂/PO) of 0.5–0.7. In addition, a considerable amount of 1,3-oxathioran-4-methyl-2-thion was isolated as a by-product.