KINETIC EFFECTS OF FLUORINE SUBSTITUENTS IN FREE-RADICAL CHEMISTRY - HYDROGEN-ATOM ABSTRACTION REACTIONS OF PERFLUORO-N-ALKYL RADICALS

被引：16

作者：

DOLBIER, WR

RONG, XX

机构：

[1] Department of Chemistry, University of Florida, Gainesville

来源：

JOURNAL OF FLUORINE CHEMISTRY | 1995年 / 72卷 / 02期

关键词：

KINETIC EFFECTS; FREE-RADICAL CHEMISTRY; HYDROGEN-ATOM ABSTRACTION; PERFLUORO-N-ALKYL RADICALS; NMR SPECTROSCOPY; MASS SPECTROMETRY;

D O I：

10.1016/0022-1139(94)00413-A

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

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.

引用

页码：235 / 240

页数：6

共 18 条

[1]

Newcomb, Tetrahedron, 49, (1993)

[2]

Avila, Ingold, Lusztyk, Dolbier, Pan, J. Am. Chem. Soc., 115, (1993)

[3]

Avila, Ingold, Lusztyk, Dolbier, Pan, Muir, J. Am. Chem. Soc., 116, (1994)

[4]

Dolbier, Rong, Pan, Smart, J. Am. Chem. Soc., 116, (1994)

[5]

Citterio, Minisci, Porta, Sesana, J. Am. Chem. Soc., 99, (1977)

[6]

Chatgilialoglu, Ferrari, Lucarini, A comment on the use of triethylsilane as a radical-based reducing agent, The Journal of Organic Chemistry, 58, (1983)

[7]

Chatgilialoglu, Dickhaut, Giese, J. Org. Chem., 56, (1991)

[8]

Chatgilialoglu, Ingold, Scaiano, J. Am. Chem. Soc., 103, (1981)

[9]

Lusztyk, Maillard, Ingold, J. Org. Chem., 51, (1986)

[10]

McMillen, Golden, Hydrocarbon Bond Dissociation Energies, Annual Review of Physical Chemistry, 33, (1982)

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