Polymerization of oxiranes by polymeric organoantimony oxides

Polymeric arylantimony(V) oxides [poly(ArSbO2), Ar = phenyl, p‐chlorophenyl (CPh), and p‐methylphenyl (Tol)] were employed as catalysts for the polymerization of oxirane [ethylene oxide (EO)] and also substituted oxiranes [propylene oxide (PO), 1,2‐butylene oxide (BO), and epichlorohydrin (ECH)]. The polymerization of EO by ArSbO2s proceeded 3–60 times faster than that by the other organoantimony and ‐tin compounds such as triphenylstibine oxide (Ph3SbO) and arenestannoic acids (ArSnO2H), respectively. Apparent activation energy for the polymerization of EO was estimated as 13.7, 13.3, and 13.6 kcal/mol for PhSbO2, TolSbO2, and CPhSbO2, respectively. The results of the polymerization as well as 1H‐, 13C‐, and 17O‐NMR spectroscopy suggested that the polymerization was initiated by ArSbO2 or Ar2Sb2O4 fragments, which was derived from a nucleophilc solvation of the polymeric ArSbO2 by oxiranes in situ.