Stopcock, ‘Rotaflo

Solvent. Nltromethane (Aldrich) was kept In a vacuum ampoule equipped with a Rotaflo stopcock over calcium hydride. It was distilled Into the reaction vessels on a vacuum line. 

Monomer. 2,6,7-Trloxablcyclo[2.2.1]heptane was prepared by the OOP method (18) and was kept In a vacuum ampoule (equipped with a Rotaflo stopcock) over a sodium mirror. Samples for polymerization were prepared by distillation of the monomer In a vacuum system to ampoules equipped with breakseals. 

Initiator. l,3-Dloxolan-2-yllum hexafluoroantlmonate was prepared and handled as described by Stolarczyk, Kublsa and Penczek (34). Solutions of the salt were prepared In vacuum flasks equipped In Rotaflo stopcocks. Trlphenylmethyl hexafluoroantlmonate (Ozark-Mahonlng) was purified In precipitation from dlchloromethane solution by hexane. 

Chemicals. Methylene chloride, CH2CI2, (Fluka, pure) was purified according to standard procedure (34). Then it was dried and distilled from CaH2 to an ampule with a Rotaflo stopcock installed on a high vacuum line and used under dry argon. 

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