Studies on the mechanism of the stereospecific polymerization. Asymmetric‐induction polymerization of benzofuran by use of optically active organo‐stannic compounds

In connection with our previous study on the system triethylaluminum/stannic chloride as a catalyst for the polymerization of vinyl ethers, the effects of ether compounds on the ionic properties of the binary system were investigated. Furthermore, benzofuran was polymerized with the aid of the ternary systems involving various asymmetric compounds. (—)Menthoxytriethyltin was found to be effective as third component for preparation of polybenzofuran with high optical activity. From data of the elemental analyses and the electric conductivity measurements of the catalytic system as well as the polymerization results the properties of the counter‐ion in the asymmetric polymerization are discussed.