KINETICS OF REACTIONS OF 2,6-DNFB WITH PYRROLIDINE AND PIPERIDINE
147
1
4a
14
over sodium. The solvents were purified as usual and all
˚
of them were kept over 4 A molecular sieves and stored in
ꢃ. The kinetic response patterns of k values vs
A
XCoS corresponding to the three nucleophiles are
characterized by exhibiting negative deviations
from the ideal response, ꢂ* being the dominant
solvent property. On the other hand, the EAc–AcN
mixtures exhibit a nearly linear response for ꢂ*,
positive deviations for ꢁ and a small synergism for
special vessels that allow delivery without air contamina-
tion. All binary mixtures were prepared prior to use and
stored under anhydrous conditions.
The kinetics of the reactions were studied by UV–
visible spectrophotometry. A Perkin-Elmer Model 124
spectrophotometer was used, equipped with a data-
acquisition system.
The parameters of solvation which minimize the
square residuals of the kA values were computed by
non-linear regressions using the MATLAB 5.2 program.
14b
ꢃ. The corresponding kinetic response patterns of
kA values show positive deviations from the ideal
response in reactions with PYR, for which ꢁ is
dominant, and an ideal response in reactions with
PIP, which are dominated by ꢂ* and ꢁ properties.
Finally, the solvatochromic response for AcN–
CHCl mixtures is characterized by a small syner-
3
14a
gism for ꢂ* and positive deviations for ꢁ and ꢃ.
Acknowledgements
The corresponding kinetic response exhibits negative
deviations from ideal behavior, ꢂ* being the domi-
nant solvent property as in the case of EAc–CHCl3
mixtures.
We are indebted to the Universidad Nacional del Litoral
(UNL), Rep u´ blica Argentina. This work received finan-
cial support from the Science and Technology Secretar-
iat, UNL, CAI þ D Program (Projects 2000-17-151,
2002-21-152 and 2002-21-153).
The above considerations allow us to conclude
that for solvent systems A (HBA þ HBD) and B
(
HBA þ HBA/HBD), the solvatochromic process
and the kinetic process are related to each other.
This correspondence might come from similar solva-
tion mechanisms.
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8
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1
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EXPERIMENTAL
,6-DNFB was synthesized as reported previously.
PYR and PIP were refluxed for 3 h and then fractionated
15
2
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Copyright # 2004 John Wiley & Sons, Ltd.
J. Phys. Org. Chem. 2004; 17: 138–147
Mancini
