Reactions of methyl radicals with poly(vinylacetophenone) during photolysis

✍ Scribed by N.A. Weir; J. Arct

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 286 KB
• Volume: 23
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(87)90095-4

✦ Synopsis

The photochemistry of isotopically labelled poly(vinylacetophenone) (PVAP) has been investigated, with a view to determining the point of H-atom abstraction from the polymer. Poly(ct-Dvinylacetophenone) (DPVAP) and poly [3.[3 dideuterovinyl(acetophenone) (D2PVAP) were irradiated under high vacuum with long wave u.v. radiation (>~ 300 nm). From the nature of the gaseous products, it was confirmed that both underwent initial photo-decomposition by a Norrish Type I reaction. Rates of abstraction reactions by CH3 and CH3CO radicals from DPVAP were subject to an isotope effect of 8.3; the corresponding rates for D2PVAP were about 85% of those observed for PVAP. In addition, no significant yields of deuterated products were obtained from D2PVAP. It is concluded that abstractions occur preferentially at the ~t-C-atom, in line with predictions based on the energetics of abstraction reactions. Molecular weight increases (due to cross-linking which involves interactions of macro-radicals generated by abstraction reactions) confirm the involvement of the ~-C-atom.