High resolution nuclear magnetic resonance spectra of two kinds of poly(vinyl chloride) and the model compounds, meso and racemic 2,4‐dichloropentane were studied by normal and spin decoupling technique to elucidate the polymer structure. Unlike the methylene resonance of meso 2,4‐dichloropentane which has been observed as an AB type quartet, only a singlet has been observed as the methylene resonance in isotactic sequences of poly(vinyl chloride) in spin‐decoupled spectra. Two peaks of decoupled spectra of the polymer at 7.76 and 7.96 τ are due to methylene protons in isotactic and syndiotactic sequences in the diad, respectively, and the other three peaks at 5.43, 5.53, and 5.69τ correspond, respectively, to syndiotactic, heterotactic, and isotactic units in the triad. By analyzing decoupled spectra of the two kinds of polymer, parameters of local regularity have been determined. A theoretical treatment for the spectrum for four nuclei ABX 2 has been applied to analysis of the methylene resonance of meso 2,4‐dichloropentane.
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Shiroh Satoh (1964) studied this question.
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