| Abstract: | α-Methylstyrene has been polymerized with lithium, sodium and potassium naphthalene in tetrahydropyran, tetrahydrofuran and 1.2-dimethoxyethane at ?30°. The tacticity of the polymers was determined by NMR. spectroscopy. Within the limits of reliability no influence of the cation on the tacticity was observed. With growing polarity of the solvent a slight but definite trend towards higher stereospecifity was noticed. The distribution of isotactic and syndiotactic links is purely statistical. The considerable dependence of tacticity upon the polymerization mechanism is ascribed to differences in the steric configuration of carbanions and carbonium ions due to different hybridization. |
