The dehydrochlorination of poly(vinyl chloride) (PVC) with LiC1 in dimethylformamide (DMF) is distinguished by the formation of polyenic products exhibiting an optical absorption peak at a wavelength greater than 500 nm. PVC dehydrochlorinated by other means usually absorbs below 450 nm. Since optical absorption characterizes the polyene sequence length distribution, we can assume that more polyenes with a large number of conjugated double bonds are formed. Investigating the influence of reaction conditions on the formation of long conjugated polyenes, a strong influence of reaction temperature and polymer concentration in the reaction system was found. Polyenes with an absorption peak at 630 nm could be prepared by adding an inert matrix polymer and hydrogen chloride. The mechanism of the formation of long polyene sequences is discussed by means of an ineffective CI-CI substitution, which changes the substituent configuration on the PVC backbone and thus creates steric opportunities for dehydrochlorination.
Посилання на статтю:
Chemical dehydrochlorination of poly(vinyl chloride) by LiCI in dimethylformamide / A. Holliinder, H. Zimmermann* and J. Behnisch // Polymer. – 1992. – Vol 33. – P. 637-642.