SPECIFIC POLYMER-SOLVENT INTERACTION AND STEREOSPECIFICITY OF NUCLEOPHILIC-SUBSTITUTION REACTION OF PVC

The substitution reaction of PVC with sodium benzenethiolate is studied in a series of solvents in comparison to cyclohexanone as considered in earlier work. As expected from the known influence of solvent on the nucleophile reactivity, the reaction extent is observed to be higher as the solvent polarity increases. In contrast, the stereoselective character of the reaction, as demonstrated for cyclohexanone solution, is found to hold only for solvents containing C = O or -O-function. The others deviate thoroughly from this behaviour. The results are discussed on the grounds of prior findings. They tentatively suggest that the occurrence of the definite conformational changes that are responsible for the stereoselective mechanism, strongly depends on some specific interactions of the solvent with isotactic GTTG and heterotactic GTTT triad conformations.