8
22
Russ.Chem.Bull., Int.Ed., Vol. 50, No. 5, May, 2001
Polyakova et al.
Table 2. Hydrolysis constants (k) and half reaction times (τ1/2
)
comparison. It has a resembling, although less pro-
of sorbates under study at 293 K
nounced shape than that in the case of D O.
2
The half reaction period of compounds 1 and 2 at
pH 7, according to the chromatographic data, is about
2.5 h (see Table 2). This corresponds to approximately
half an increase in the SDC values, and 5 h after the
curve of SDC changing reaches a plateau (see Fig. 2).
Thus, the PFG NMR studies gave the results that
agree well with the kinetic parameters of hydrolysis
obtained in the chromatographic experiment.
Sorbate pH
k*/min1
τ1/2/min
4.54103±5.1210
4
4
4
4
4
1
2
7
4
7
8
7
9
151.0±20.2
128.8±15.5
151.0±10.1
220.1±35.7
144.9±4.50
172.9±10.9
5.38103±8.9310
4.59103±3.0410
3.15103±6.5510
4.78103±1.2810
3
4.01103±1.78104
*
n = 5, P = 0.95.
This work was financially supported by the Federal
Target Program "Integration" (Project No. KO 357).
1
0
2 1
D10 /m s
4
References
3
1
3
2
2
2
8
4
1. N. M. Ezhova and O. A. Pisarev, Tez. dokl. Vseros. simpoz.
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2
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t/h
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Fig. 2. Plots of SDC vs. time of a 1% solution of 1-tosyl-
benzimidazole 2 (1); a 3% solution of 1-mesylimidazole 1 (2)
in D O, and a 1% solution of 1-mesylimidazole in H O (3) at
4
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2
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The hydrolysis reaction in the general form can be
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. T. L. Gilchrist, Heterocyclic Chemistry, J. Wiley and Sons,
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RSO Het + H O
2
RSO OH + HetH,
2
2
7
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R = Me, 4-MeC H ; Het = imidazolyl, benzimidazolyl,
benzotriazolyl.
6
4
8
9
. G. M. Kotikov and V. E. Lerner, Zh. Nevropatologii i
Psikhiatrii [J. of Neuropathology and Psychiatry], 1990, 3,
The rate constants and half reaction periods for
hydrolysis of compounds 13 are presented in Table 2.
The hydrolysis rate constants of the studied substrates
are close, and hydrolysis is completed for 5 h. It can
easily be seen that the rate constants increase when pH
decreases. Thus, we can assume that hydrolysis of these
compounds can be catalyzed by acids.
1
32 (in Russian).
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1
1
1
1
1
0. P. P. Purygin, A. V. Dragunova, L. V. Limareva, and O. P.
Danil´chenko, Khim.-Farm. Zh., 1998, 32, No. 5, 19 [Pharm.
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1. Kratkii spravochnik khimika [Brief Chemist´s Reference Book],
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The plots of the self-diffusion coefficients of mesyl-
and tosyl-substituted derivatives of 1 and 2 vs. time at
3
09 K are presented in Fig. 2. The coefficient for pure
water at the same temperature is given for comparison
curve 4). It is seen that the plot of SDC for compound
(curve 1) has a characteristic shape: for the first 1.5 h
(
2
the coefficient values are lower than the SDC of H O by
2
almost 35%, then they increase virtually achieving the
SDC of H O and remain unchanged for ∼ 1 h, then
2
4. T. A. Gloriozova, D. A. Filimonov, A. A. Lagunin, and
V. V. Poroikov, Khim.-Farm. Zh., 1998, 32, No. 12, 33
[Pharm. Chem. J., 1998, 32, No. 12 (Engl. Transl.)].
somewhat decrease, and further remain unchanged (by
1
015% lower than the SDC of H O). The same
2
tendency of SDC changing is observed for compound 1
curve 2). A similar plot for a solution of tosyl-substi-
tuted derivative 2 in water (curve 3) is presented for
(
Received March 3, 2000;
in revised form August 28, 2000