Oxepine, polymerization

Ethylene oxide 3 may be cyclodimerized to 1,4-dioxan 4 in the presence of superacids, like chlorosulfonic or perchloric acid (Equation 1). The reaction was accelerated by aprotic dipolar solvents, but was retarded by less polar solvents. Chlorosulfonic acid also catalysed ring-opening polymerization of the saturated oxygen heterocycle oxepine 5 to the polymer 6 (Equation 2). ... 

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