Boron trifluoride dibutyl etherate

The copolymerization of trioxane with cyclic ethers or formals is accomplished with cationic initiators such as boron trifluoride dibutyl etherate. Polymerization by ring opening of the six-membered ring to form high molecular weight polymer does not commence immediately upon mixing monomer and initiator. Usually, an induction period is observed during which an equilibrium concentration of formaldehyde is produced. 

Materials. Trioxane (Celanese) was purified by refluxing over metallic sodium followed by distillation (b.p., 114.3°C.). Ampoules of ethylene oxide (Eastman white label) were opened immediately before use. The purity was established by mass spectrometry. Boron trifluoride dibutyl etherate (Eastman white label) was used without further purification. 

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