Absolute rate constants for some hydrogen atom abstraction reactions by a primary fluoroalkyl radical in water.
A combination of laser flash photolysis and competitive kinetic methods have been used to measure the absolute bimolecular rate constants for hydrogen atom abstraction in water from a variety of organic substrates including alcohols, ethers, and carboxylic acids by the perfluoroalkyl radical, *CF(2)CF(2)OCF(2)CF(2)SO(3)(-) Na(+). Comparison, where possible, of these rate constants with those previously measured for analogous reactions in the non-polar organic solvent, 1,3-bis(trifluoromethyl)benzene (J. Am. Chem. Soc, 1999, 121, 7335) show that the alcohols react 2-5 times more rapidly in the water solvent and that the ethers react at the same rate in both solvents. A transition state for hydrogen abstraction that is more reminiscent of an "intimate ion pair" than a "solvent separated ion pair" is invoked to explain these modest solvent effects.
Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA.
Li
L
Zhang
Joseph
J
Cradlebaugh
Grzegorz
G
Litwinienko
Bruce E
BE
Smart
Keith U
KU
Ingold
William R
WR
Dolbier