KINETIC EFFECTS OF FLUORINE SUBSTITUENTS IN FREE-RADICAL CHEMISTRY - HYDROGEN-ATOM ABSTRACTION REACTIONS OF PERFLUORO-N-ALKYL RADICALS
Dolbier, WR; Rong, XX
| HERO ID | 4854517 |
|---|---|
| In Press | No |
| Year | 1995 |
| Title | KINETIC EFFECTS OF FLUORINE SUBSTITUENTS IN FREE-RADICAL CHEMISTRY - HYDROGEN-ATOM ABSTRACTION REACTIONS OF PERFLUORO-N-ALKYL RADICALS |
| Authors | Dolbier, WR; Rong, XX |
| Journal | Journal of Fluorine Chemistry |
| Volume | 72 |
| Issue | 2 |
| Page Numbers | 235-240 |
| Abstract | Using competitive methods, the rates of hydrogen-atom abstraction by a typical perfluoro-n-alkyl radical, n-C7F25; have been determined for a series of silane and stannane reductants including (n)Bu(3)Sn-H (2.03 X 10(8) M(-1) s(-1)), Et(3)Si-H (7.5 X 10(5)), (TMS)(2)SiMe-H (1.63 X 10(7)) and (TMS)(3)Si-H (5.1 X 10(7)), all of which exhibited substantial rate enhancements relative to their analogous reductions of hydrocarbon radicals. The reduction by PhSH is, in contrast, similar to 400-times slower than for hydrocarbon radicals. Transition state polar effects are invoked to rationalize the relative reactivity of perfluoro- versus hydrocarbon radicals in these hydrogen-transfer reactions. A Hammett study for H-atom transfer from arene thiols (rho+ = -0.56) provided further substantiation for this conclusion. A discussion of the relative reactivity of t-butoxyl and perfluoro-n-alkyl radicals is presented. |
| Doi | 10.1016/0022-1139(94)00413-A |
| Wosid | WOS:A1995RD58200013 |
| Is Certified Translation | No |
| Dupe Override | No |
| Is Public | Yes |
| Keyword | KINETIC EFFECTS; FREE-RADICAL CHEMISTRY; HYDROGEN-ATOM ABSTRACTION; PERFLUORO-N-ALKYL RADICALS; NMR SPECTROSCOPY; MASS SPECTROMETRY |