Stereoselective nucleophilic substitution on poly(vinyl chloride) in concentrated dioctylphthalate solution as an approach to substitution in the melt

✍ Scribed by C. Mijangos; G. Martínez; A. Méndez; J.M. Gómez-Elvira; J. Millán

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 289 KB
• Volume: 25
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(89)90150-x

✦ Synopsis

The nucleophilic substitution of a commercial poly(vinyl chloride) sample, with sodium benzenethiolate, was studied at 150 ° in dioctylphthalate (DOP), in which the polymer and the nucleophile are soluble and insoluble, respectively. Some experiments of substitution in the melt in the presence of moieties of DOP were also performed for comparison. The conversion curves showed a fast reaction period followed by a plateau, the level of which increased linearly with increasing amount of nucleophile and was considerably lower than expected from the stoichiometric proportions used. Decreasing DOP, for a given polymer/nucleophile ratio, resulted in an increasing efficiency of the nucleophile, approaching that in the melt. The change of the content of iso, hetero and syndiotactic triads, as measured by [~3C]NMR, with the degree of substitution was found to be of the type observed either in cyclohexanone dilute solution or in the melt. The results, as compared to those previously obtained, allow a better knowledge of physical features affecting reaction yields in the molten state and of the conformational character of the reaction mechanism.