An investigation on the mechanism of homogeneous cationic polymerization of methyl vinyl ether by NMR spectroscopy

Methyl vinyl ether‐α.β‐d 2 was synthesized and polymerized with BF 3 ·OEt 2 or stannic chloride‐trichloroacetic acid as catalyst at −78 up to 0°C in toluene or methylene chloride. The NMR spectra of the polymers were determined on nitromethane solutions and the triad tacticity was obtained from the methoxyl absorptions. Pentad resonances were observed on chlorobenzene solutions. Tetrad resonances were assigned from the methylene proton absorptions in the deuterium‐decoupled spectra, assuming that the polymerization proceeded according to the first‐order MARKOVIAN trial. It was found that the proportions of the two meso methylene protons were nearly equal irrespective of polymerization conditions and the mode of double bond opening was discussed.