POLYMERIZATION OF 1,3-DIOXEPAN .I. STRUCTURE OF POLYMER AND THERMODYNAMICS OF ITS FORMATION AND A NOTE ON 1,3-DIOXAN

1,3-Dioxepan was polymerized under vacuum in methylene dichloride solution by anhydrous perchloric acid. The reaction involves a perfectly clean monomer-polymer equilibrium. The oligomers and polymers are cyclic and are formed by a ring-expansion mechanism. For the initial monomer concentrations between 0·3 and 1 m and temperatures between -65° and +5°C, ΔHss0 = -3·6 ±0·3 kcal mole-1, ΔSss0 = -11·5 ± 1·5 cal deg-1 mole-1; for the 1 m solution the ceiling temperature is +27°C. The only product obtainable from the attempted polymerization of 1,3-dioxan was a mixture of crystalline cyclic dimer and trimer. © 1969.