Equilibrium concentration of trioxane in cationic polymerization

In the cationic polymerization of trioxane and tetraoxane near room temperature, the equilibrium trioxane concentration is not negligible during polymerization. In this work, tetraoxane was polymerized with BF 3 • O(C 2 H 5 ) 2 in various solvents and the equilibrium concentration of trioxane produced during the polymerization of tetraoxane and equilibrated with the growing polyoxymethylene chain was determined. The equilibrium trioxane concentrations were 0.05, 0.13, and 0.19 mole/l. in benzene, ethylene dichloride, and nitrobenzene at 30°C, respectively, and 0.20 mole/l. in thhylene dichloride at 50°C. The values in ethylene dichloride showed that the approximate values of Δ H p and Δ S were −4.2 kcal/mole and −9.7 cal/mole‐deg., respectively.