The sensitized photodehydrochlorination of poly(vinyl chloride)—II. Model compound studies

p-Cresol, a model compound for an additive shown previously to be a potent photosensitizer of dehydrochlorination in poly(vinyl chloride) PVC, has been shown to sensitize dehydrochlorination in t-butyl chloride, a model for PVC. A quantitative study of the effect of chlorinated alkanes upon the fluorescence of p-cresol in solution reveals that quenching is due to charge transfer interactions, the halogenated compound acting as electron acceptor. Since the mono-halo compound t-butyl chloride does not quench p-cresol fluorescence, it was concluded that the photosensitization occurs via the triplet state of the p-cresol, and this view was confirmed by addition of triplet quenchers. A mechanism for the reaction is proposed, initial exciplex formation being followed by electron transfer.