10.1021/ja954268f.s002
Osama M. Musa
Osama M.
Musa
John H. Horner
John H.
Horner
Haifa Shahin
Haifa
Shahin
Martin Newcomb
Martin
Newcomb
A Kinetic Scale for Dialkylaminyl Radical Reactions
American Chemical Society
1996
order rate constants
hydrogen atom donors
unimolecular rate constants
methyl
Bu 3 SnH
dialkylaminyl radicals
Calibrated hydrogen atom donors
tran
tin hydride reactions
Dialkylaminyl Radical Reactions
PTOC
alkyl radicals
1996-04-24 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/A_Kinetic_Scale_for_Dialkylaminyl_Radical_Reactions/3659382
A kinetic scale for dialkylaminyl radicals was established by
measuring unimolecular rate constants for a
series of dialkylaminyl radical clocks that spans eight orders of
magnitude and using clock reactions to measure the
second order rate constants for reactions of several hydrogen atom
donors. <i>N</i>-Hydroxypyridine-2-thione
derivatives
of carbamic acids (so-called PTOC carbamates) were used as radical
precursors in direct, laser-flash kinetic
measurements and in indirect, radical chain kinetic studies. The
calibrated radical clocks are
<i>N</i>-methyl-6,6-diphenyl-5-hexenaminyl,
<i>N</i>-methyl-<i>trans</i>-5-phenyl-4-pentenaminyl,
<i>N</i>-methyl-5,5-diphenyl-4-pentenaminyl,
<i>N</i>-methyl-<i>trans</i>-2-phenylcyclobutanaminyl, and
<i>N</i>-methyl-<i>trans</i>-2-phenylcyclopropanaminyl.
Calibrated hydrogen atom donors are
Bu<sub>3</sub>SnH, <i>t</i>-BuSH, PhSH, and PhSeH.
Whereas the tin hydride reactions with dialkylaminyl radicals are
slower than
reactions with alkyl radicals, the polarity-matched reactions of the
electron-rich dialkylaminyl radicals with the electron-poor hydrogen donors <i>t</i>-BuSH, PhSH, and PhSeH have rate
constants nearly equal to those for reactions of alkyl
radicals with the same donor.