Substituent effects on benzylic radical hydrogen hyperfine coupling constants. Part 4. The effect of branching of the alkyl substituent
- 1 September 1985
- journal article
- Published by Canadian Science Publishing in Canadian Journal of Chemistry
- Vol. 63 (9) , 2378-2383
- https://doi.org/10.1139/v85-394
Abstract
The effects of substituents in the meta and para positions of the benzyl radical on the α-hydrogen hyperfine coupling constants (hfc's) are discussed. The electron spin resonance (esr) spectra of the para-methyl, ethyl, isopropyl, and tert-butyl substituted benzyl and cumyl radicals are analysed. Hyperconjugation involving the C—C bond is 40–60% as effective as C—H hyperconjugation for delocalizing spin density. This conclusion is supported by INDO molecular orbital calculations. Similar analysis of the 13Cmr spectra of the para-alkyl substituted cumyl carbocations provides evidence that C—C hyperconjugation is 75–90% as effective as C—H hyperconjugation for delocalizing charge density.Keywords
This publication has 0 references indexed in Scilit: