Primary alkyl radicals: Can they be persistent?

✍ Scribed by David Griller; Paul R. Marriott

• Book ID: 102446965
• Publisher: John Wiley and Sons
• Year: 1979
• Tongue: English
• Weight: 179 KB
• Volume: 11
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550111103

✦ Synopsis

Abstract

The structure of t‐Bu~3~SiċH~2~, (I), suggested that it might be a persistent primary alkyl radical since it has (i) a bulky group to protect the radical center; (ii) no β‐hydrogens, so that a radical‐radical disproportionation reaction is impossible; (iii) a β‐silicon atom, which should prevent β‐scission of tert‐butyl as a unimolecular decomposition pathway. However, the self‐reaction of (I) in isooctane was found to be a diffusion controlled process with log(A/M^−1^ sec^−1^) = 10.7 ± 0.3 and E = 2.5 ± 0.2 kcal mole^−1^. Hence (I) is not persistent and it is concluded that a persistent primary alkyl will only be observed when the—ĊH~2~ moiety is deeply buried among sterically protecting groups.