Collect. Czech. Chem. Commun. 1995, 60, 1303-1309

Theoretical Study of Thermal Dehydrochlorination of Poly(vinyl chloride) Initiated by Tertiary Chlorine Groupings

Jaroslav Burdaa and Rudolf Lukášb

a Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 162 06 Prague 6, Czech Republic
b LUKAS Research, Doubravinova 1/219, 163 04 Prague 6, Czech Republic


Thermal dehydrochlorination of syndiotactic poly(vinyl chloride) sequences initiated by structural defects possessing chlorine atoms bound on tertiary carbon atoms (branched structures) was theoretically studied on the low-molecular-weight models using the semiempirical quantum chemical methods MNDO and AM1. The results are compared with those obtained previously by studying the dehydrochlorination in syndiotactic sequences without defects. It was found that elimination of the first HCl molecule is much easier in the branched structure. However, this effect fast decreases with dehydrochlorination continuing along the chain due to its distinct localization in the closest vicinity of tertiary carbon atom. A detailed evaluation of possible radical and ionic intermediates revealed that for ionic mechanism of dehydrochlorination the effect of branching is perceptible slightly longer.