NMR spectrum of poly(propene sulfide)

The 100 MHz spectra of polymers of propene sulfide and propene‐2‐d1 sulfide have been determined in CDCl3, CCl4, and C6D6. In the deuterated polymer the main‐chain protons give rise to two overlapping AB quartets in which the two pairs of upfield B lines are coincident and the two pairs of downfield A lines are resolved. With CdCO3 as polymerization catalyst the downfield quartet is twice as strong as the upfield quartet. The former is ascribed to an isotactic dyad: magnified image and the latter to a syndiotactic dyad: magnified image Other catalysts (ZnCO3, CuCO3, SiO2/Al2O3, Na) produce an essentially atactic structure. The values τA = 7.125, τA′ = 7.155, τB = 7.45, JAB = −12.9 Hz, derived from the spectrum of the deuterated polymer (in CCl4) were used to obtain the following values from the spectrum of the undeuterated polymer (tertiary proton = Hc): τC = 7.131, JBC = 10.0 Hz, JCA = 4.1 Hz. The magnitudes of the vicinal coupling constants indicate a preferred trans conformation for the mainchain CC bond. τA, τB, and τC are somewhat dependent on solvent; τCH3 = 8.63, independent of solvent, and JCH3, HC = 6.2 Hz.