Stereochemical Factors in Epoxide Polymerization by Base and Coordination Catalysts

Abstract

The amorphous fraction accompanying isotactic poly (propy-lene oxide) or poly(tert-butylethylene oxide) formed by co-ordination catalysts was shown by degradation to the dimer glycols to involve inversion of configuration at every ring opening at the secondary carbon atom for (R) - [or (S) -] PO and to involve no stereoselection in the coordination step for tert-BuEO. The crystalline poly(tert-BuEO) formed by polymerization with tert-BuOK was similarly shown to give equal amounts of erythro and threo dimer glycol. It is proposed that these dimer units arise from regular alternate isotactic and syndiotactic placements (iso,syn). Aryl glycidyl