Photoinitiated Radical-Forming Reactions of 2-Quinolinecarbonitrile At 77 and 331 K

Article abstract of DOI:10.1021/jo00314a007

The photoinitiated dimerization of 2-quinolinecarbonitrile (1) in HCl-acidified 2-propanol/water (4:1) has been studied at 77 and 331 K at 250, 300 and 350 nm in unsensitized and benzophenone- and biphenyl-sensitized reactions.One principal product, a dimer lactam (5), is formed at all wavelengths through a triplet state of 1.ESR spectra taken in ethanol at 77 K show a signal for ethyl radical which is formed by a biphotonic process with 1 in acid solution.A mechanism is proposed for the reaction at 331 K which involves an electron transfer from 2-propanol to an upper triplet state of 1.