ACTIVATION PARAMETERS OF TRANSESTERIFICATION OF 4-NITROPHENYL ACETATE
1199
result from desolvation upon formation of transition
state with benzenethiol (III) [4]. The reactions of
4-nitrophenyl acetate (I) with nucleophiles II and III
remain enthalpy-controlled since the enthalpy contri-
bution to ∆G≠ is larger than the contribution of entropy
(Table 3).
The relative rate constants were calculated by the fol-
lowing equation [14]:
kI/kVI = (logAI, 0 – logAI, τ)/(logAVI, 0 – logAVI, τ),
where AI, 0 and AVI, 0 are the initial concentrations of
compounds I and VI (M), and AI, τ and AVI, τ are their
concentrations at a moment of time τ (M). The apparent
rate constants k for the reactions of 4-nitrophenyl
acetate I with nucleophiles II and III were calculated
from the rate constants determined previously for anal-
ogous reactions of 4-nitrophenyl benzoate (VI) [3, 4]
and the corresponding relative rate constants for I and
VI (Table 1).
EXPERIMENTAL
The reaction mixtures were analyzed by GLC on
an LKhM-72 chromatograph equipped with a thermal
conductivity detector; linear oven temperature prog-
ramming from 50 do 270°C at a rate of 10 deg/min;
SKTFT-803 column, VS-1 (15%) on Chromaton W;
carrier gas helium, flow rate 60 ml/min. The compo-
nents were identified by adding their authentic samples
and were quantitated by the internal normalization
method using hexamethylbenzene as standard. Com-
mercial dimethylformamide was distilled under
reduced pressure first over calcium hydride and then
over molecular sieves and was stored over molecular
sieves under argon. Commercial potassium carbonate
was preliminarily ground, passed through a 0.5-mm
sieve, calcined in a muffle furnace, and again ground
and sieved (≤0.5 mm). Commercial 4-chlorophenol
and benzenethiol were purified according to standard
procedures. 4-Nitrophenyl acetate (I), 4-chlorophenyl
acetate (IV), and S-phenyl thioacetate (V) were synthe-
sized according to the procedures described in [11–13],
and their physical constants were consistent with
published data.
REFERENCES
1. Buncel, E. and Um, I.H., J. Chem. Soc. Chem.
Commun., 1986, p. 595; Um, I.H., Chung, E.K., and
Kwon, D.S., Tetrahedron Lett., 1997, vol. 38, p. 4787.
2. Os’kina, I.A. and Vlasov, V.M., Russ. J. Org. Chem.,
2006, vol. 42, p. 865; ibid., 2008, vol. 44, p. 561.
3. Os’kina, I.A. and Vlasov, V.M., Russ. J. Org. Chem.,
2009, vol. 45, p. 523.
4. Os’kina, I.A. and Vlasov, V.M., Russ. J. Org. Chem.,
2010, vol. 46, p. 326.
5. Vlasov, V.M., Usp. Khim., 2006, vol. 75, p. 851.
6. Um, I.H. and Buncel, E., J. Org. Chem., 2000, vol. 65,
p. 577.
7. Taft, R.W., Koppel, I.A., Topsom, R.D., and Anvia, F.,
J. Am. Chem. Soc., 1990, vol. 112, p. 2047.
8. Gordon, A.J. and Ford, R.A., The Chemist’s Com-
panion, New York: Wiley, 1972. Translated under the
title Sputnik khimika, Moscow: Mir, 1976, p. 158.
9. Oh, H.K., Kim, S.K., Lee, H.W., and Lee, I., J. Chem.
Soc., Perkin Trans. 2, 2001, p. 1753.
10. Parker, A.J., Chem. Rev., 1969, vol. 69, p. 1; Cramp-
ton, M.R. and Stevens, J.A., J. Chem. Soc., Perkin
Trans. 2, 1990, p. 1097; ibid., 1989, p. 925; Ruff, F.,
Internet Electron. J. Mol. Des., 2004, vol. 3, p. 474.
11. Okahata, Y., Ando, R., and Kunitake, T., J. Am. Chem.
Soc., 1977, vol. 99, p. 3067.
Determination of relative rate constants for the
reactions of compounds I and VI with 4-chloro-
phenol (II) and benzenethiol (III). A flask main-
tained at a constant temperature was flushed with
argon and charged with compounds I and VI, 4-chloro-
phenol (II) or benzenethiol (III), and K2CO3 at a ratio
of 5 :5 :1:2, and dimethylformamide was added to
attain a concentration of I and VI of ~10–2 M. The
mixture was kept for a required time (no longer than
for 60 min) at a definite temperature (15–36°C), and
the reaction was terminated by adding a mixture of
5 ml of chloroform and 5 ml of 5% hydrochloric acid.
The organic layer was separated, washed with 10 ml of
water, and dried over CaCl2, the solvent was removed,
and the residue was weighed and analyzed by GLC.
12. Klarmann, E., Shtenov, V.A., and Gates, L.W., J. Am.
Chem. Soc., 1933, vol. 55, p. 2576.
13. Tarbell, D.S. and Herz, A.H., J. Am. Chem. Soc., 1953,
vol. 75, p. 1668.
14. Investigation of Rates and Mechanisms of Reactions,
Bernasconi, C.F., Ed., New York: Wiley, 1986, part 1,
p. 203.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 9 2012