Kombination und disproportionierung von modellradikalen für die wachsende polystyrolkette

✍ Scribed by Gleixner, Günther ;Olaj, Oskar Friedrich ;Breitenbach, Johann Wolfgang

• Publisher: Wiley (John Wiley & Sons)
• Year: 1979
• Weight: 629 KB
• Volume: 180
• Category: Article
• ISSN: 0025-116X
• DOI: 10.1002/macp.1979.021801103

✦ Synopsis

Abstract

The mechanism of the bimolecular reaction between the model radicals for polystyryl: 1‐phenylethyl, 1‐phenylpropyl, and 1,3‐diphenylpropyl radical is investigated by means of gas chromatography. The radicals are generated either at 80°C by thermal or at 20°C by photochemical decomposition of the corresponding azoalkanes in benzene solution. At 80°C 7,5% of the 1‐phenylethyl radicals, 12,9% of the 1‐phenylpropyl radicals, and 13,5% of the 1,3‐diphenylpropyl radicals undergo disproportionation. Since the structure of these model radicals approaches that of the growing polystyrene chain in this order one may expect polystyryl radicals to disproportionate to about the same extent as 1,3‐diphenylpropyl radicals. In photolysis experiments evidence for ortho coupling of 1‐phenylalkyl radicals is found. Photoisomerisation of this ortho coupling product leads to the formation of a small amount of a thermally stable unsymmetrical dimer.