Substituent effects on the CC bond strength, 18. Stabilization of alkyl radicals by 4-pyridyl, 1-naphthyl or 2-naphthyl substituents in α-position
✍ Scribed by Herberg, Clemens ;Peyman, Anuschirwan ;Nölke, Margot ;Beckhaus, Hans-Dieter ;Rüchardt, Christoph
- Publisher
- John Wiley and Sons
- Year
- 1995
- Tongue
- English
- Weight
- 360 KB
- Volume
- 1995
- Category
- Article
- ISSN
- 0947-3440
No coin nor oath required. For personal study only.
✦ Synopsis
The formation of the a-substituted radicals 1-9 with the 4pyridyl (?), l-naphthyl(8), and the 2-naphthyl(9) substituent by thermolysis of their dimers 1-3 in solution was investigated. The activation parameters of the homolysis of the central CC bond were obtained from kinetic measurements of the thermal cleavage of 1-3 in the presence of radical scavengers. These data were compared with those obtained from the thermolysis of alkanes which cleave into a-alkyl branched radicals, and which lose the same amount of strain during the dissociation. The' "strain-free'' radical stabilization enthalpies of the a-substituted radicals [RSE = 7.9 ? 1.8 (?), 12.0 & 1.4 (8), and 8.7 k 1.9 kcal/mol (9)] were obtained in this way.