REACTIVITY OF INORGANIC α-NUCLEOPHILES ... I.
357
In conclusion, it should be emphasized that, among
various classes of surfactants, those possessing a reac-
tive ion, as well as functionalized surfactants [12–15],
attract particular interest since they make it possible to
achieve considerable micellar effects without intro-
duction of additional reagents. An undoubted advan-
tage of systems based on organic complexes with tri-
bromide ion is that they are convenient in handling and
versatile reagents capable of acting as nucleophile,
oxidant, or brominating agent.
mined from the change of the optical density with time
using Eq. (3) [13, 20]:
ln(D
∞
– D
τ
) = ln(D
∞
– D
0
) – kobs τ,
(3)
where D , D , and D are the optical densities at the
0
τ
∞
initial moment, time τ, and by the end of the process,
respectively. The linear dependences were processed
by the least-squares method, and the obtained values
were characterized by mean-square deviations.
REFERENCES
EXPERIMENTAL
1
2
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Bis(N,N-dimethylacetamide) hydrogen tribromide
1), bis(N-acetylpiperidine) hydrogen tribromide (3),
and cetyl(trimethyl)ammonium tribromide (9) were
synthesized according to the procedure described in
20]. The active bromine content of complexes 1 and 3
96–98%) was determined by iodometric titration. The
(
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[
(
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molar absorption coefficient of hypobromite ion was
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4
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(
Fig. 6). The concentration of hypobromite ion in
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aqueous solutions of complexes 3 and 9 was deter-
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6
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–
1
–1
2
0 L mol cm ). The difference between the theoreti-
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7. Moutiers, G., Guével, E.L., Cannes, C., Terrier, F., and
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described in [20]. Commercial diethyl 4-nitrophenyl
phosphate (6) (≥90%, Aldrich), cetyl(trimethyl)am-
monium bromide (8) (≥99.0%, Aldrich), and inorganic
reagents of analytical and ultrapure grades were used
without additional purification. All solutions were
prepared using doubly distilled water just before
kinetic measurements and were adjusted to required
pH values by adding a small amount of concentrated
aqueous potassium hydroxide or HCl. The acidity of
the medium was measured before and after each
kinetic run with a Metrohm 744 pH meter. The kinetics
of nucleophilic cleavage of esters 5–7 was monitored
by accumulation of 4-nitrophenoxide ion (water, 25°C,
λ 400–420 nm; Thermo Electron Genesys 10S UV
spectrophotometer). The initial substrate concentration
9
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1
0. Singh, N., Karpichev, Ye., Sharma, R., Gupta, B.,
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1
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1
2. Kapitanov, I.V., Theor. Exp. Chem., 2011, vol. 47,
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1
3. Kapitanov, I.V., Belousova, I.A., Turovskaya, M.K.,
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1
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1
1
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–5
(<5×10 M) was always much lower than the initial
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nucleophile concentration. The substrate (as a concen-
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photometric cell through a capillary. The observed
6. Vakhitova, L.N., Matvienko, K.V., Skrypka, A.V.,
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–
1
pseudofirst-order rate constants kobs (s ) were deter-
17. Welton, T., Chem. Rev., 1999, vol. 99, p. 2071.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 53 No. 3 2017