Effect of the micellar surfactant nanoreactors on the reactions of 2,4-dinitrophenylhydrazine with some aldehydes

Article abstract of DOI:10.1134/S1070363208050113

By thermogravimetry, the IR and electronic spectroscopy physicochemical characteristics of systems including aromatic aldehydes, 2,4- dinitrophenylhydrazine, and a surfactant were investigated. Selective solubilization effect of the cationic surfactant (c

Full text of DOI:10.1134/S1070363208050113

ISSN 1070-3632, Russian Journal of General Chemistry, 2008, Vol. 78, No. 5, pp. 903–907. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © S.Yu. Doronin, R.K. Chernova, A.A. Burmistrova, 2008, published in Zhurnal Obshchei Khimii, 2008, Vol. 78, No. 5, pp. 761–765.
Effect of the Micellar Surfactant Nanoreactors
on the Reactions of 2,4-Dinitrophenylhydrazine
with Some Aldehydes
S. Yu. Doronin, R. K. Chernova, and A. A. Burmistrova
Chernyshevskii Saratov State University, Chemical Faculty,
Astrakhanskaya 83, building 1, Saratov, 410012 Russia
e-mail: DoroninSU@mail.ru
Received July 31, 2007
Abstract—By thermogravimetry, the IR and electronic spectroscopy physicochemical characteristics of systems
including aromatic aldehydes, 2,4-dinitrophenylhydrazine, and a surfactant were investigated. Selective solubilization
effect of the cationic surfactant (cetylpyridinium chloride) micelles on the aci-form of hydrazone arising in the
alkaline medium was found. The universal character of solubilization by the cationic surfactant micelles in the
aromatic aldehyde—2,4-dinitrophenylhydrazine systems was shown by an example of the benzaldehyde derivatives
with substituents of different nature. This effect leads to the increase in solubility of the reaction products and the
aggregative stability of solutions.
DOI: 10.1134/S1070363208050113
Reaction of 2,4-dinitrophenylhydrazine with car-
bonyl compounds (aldehydes, ketones, quinones) is
widely used in the organic [1–3] and the analytical [4–
13] chemistry. Such reactions are distinguished by
their high selectivity. The products of these reactions
proceeding as a rule in water and organic-water media
are the corresponding hydrazones. Under the action of
alkali the latter are converted to intensely colored aci-
salts II.
of 2,4-dinitrophenylhydrazine and p-dimethylamino-
cynnamaldehyde.
As it was shown previously two main reaction steps
could be distinguished. In the first stage proceeding in
the acidic medium the condensation of reagent with the
carbonyl compound takes place to form the poorly
water-soluble hydrazone (the electroneutral form I). In
the second stage proceeding in the alkaline medium the
negatively charged aci-form of the corresponding
hydrazone is formed and its solubility in water
somewhat increases. To prove that the product I
obtained in the first stage of the reaction is the
hydrazone and to evaluate its physicochemical
Effect of the micellar media of surfactants on this
type of reactions was not studied before. Considering
that the surfactant-based micellar nanoreactors can
significantly alter physicochemical properties of
systems, the aim of the present work was to establish
the effect of various types of surfactants on the
reactions of 2,4-dinitrophenylhydrazine with a series
of aromatic aldehydes (Table 1).
Table 1. Aromatic aldehydes under investigation
Aldehyde
FW
Benzaldehyde
106.12
149.19
The choice of aldehydes was determined by
different position (o-, m-, p-) and the nature of
substituents in the aromatic ring with the purpose of
evaluating the effect of these factors on the properties
of hydrazones formed and their behavior in water and
the micellar media.
p-Dimethylaminobenzaldehyde
p-Dimethylaminocynnamaldehyde
p-Methoxybenzaldehyde
p-Nitrobenzaldehyde
176.16
136.15
151.13
m-Nitrobenzaldehyde
p-Chlorobenzaldehyde
2,4-Disulfobenzaldehyde
151.13
186.5
Effect of various types of surfactants was
investigated by an example of model system consisting
262.12
903

904
DORONIN et al.
O
C
CH CH
N(CH3)2
N(CH3)2
O2N
NH NH2 +
H
NO2
H+
O2N
NH
NO2
N
CH CH CH
_H2O
I
NaOH
O
N
N
N
CH CH CH
N(CH3)2
_
Na+
O
NO2
II
characteristics the substance obtained was isolated in
solid state and investigated by thermogravimetry (Fig. 1a),
IR spectroscopy (Fig. 1b), and elemental analysis (see
Experimental).
gravimetric curve up to 200°C and the absence of the
endothermic effect corresponding to the removing of
solvent (water) on the differential curve. The sample
burns out completely (the mass loss is 100%) and
hence does not contain the inorganic admixtures.
The product obtained (Fig. 1a) does not contain the
hygroscopic and the structurally-bound water as is
confirmed by the broad plateau on the thermo-
Analysis of the IR spectrum of the hydrazone I
(Fig.1b) showed the presence of the characteristic
(a)
DTG
DTA
(b)
35%
45%
0.6
0.4
0.2
0
3500 2500
1800
1600
1450 1400 1300
900
500
Wave number, 1/cm
TG
Fig. 1. The thermogram (a) and the IR spectrum (b) of hydrazone I.
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EFFECT OF THE MICELLAR SURFACTANT NANOREACTORS
905
bands at 1600–1618 cm–1 belonging to the azomethine
group >C=N–, and also of the band at 3265 cm–1
corresponding to the N–H bond vibrations. In the IR
spectrum of the hydrazone I the absence of bands
characteristic of initial reagents was established: at
1715–1695 cm–1 (aldehyde group) and at 3200–
3500 cm–1 (NH2 group). Hence, the analytical data
obtained for the product synthesized confirm that it is
hydrazone I.
surfactants is governed by two main factors, the
electrostatic interaction of the oppositely charged aci-
form of hydrazone and the surface of the cationic
micelle of surfactant, and the presence of the
hydrophobic aromatic rings in compound II.
The optimal conditions of the reaction of 2,4-di-
nitrophenylhydrazine with other aldehydes were also
studied. The pH, the concentrations of reagent and of
cetylpyridinium chloride, the temperature, and the
order of mixing the solutions were varied. It was found
that the effect of the cetylpyridinium chloride micelles
is independent of the nature and the position of
substituent in the aromatic ring of aldehyde under the
following conditions: pH 13, CDPH 4 × 10–4 M, CCPC
6 × 10–4M, t 20–25°C, the order of mixing: dinitro-
phenylhydrazine–aromatic aldehyde–cetylpyridinium
chloride-buffer solution.
We have studied the reaction of 2,4-dinitro-
phenylhydrazine with aldehydes in the micelles of
surfactants of different nature. Introduction into the
system under study of micelles of an anionic surfactant
(sodium dodecylsulfate) does alter the reaction charac-
ter and the properties of hydrazone I and of its aci-
form II. In the micelles of nonionogenic surfactant
(OP-10) the insignificant increase in solubility of the
form I within 5–6 h was observed.
Analysis of data listed in Table 2 shows that
introduction of the electron-donor [N(CH3)2, OCH3]
and the electron-acceptor (NO2, Cl, SO3H) substituents
in the molecule of benzaldehyde practically does not
influence such charactristics of the hydrazones
obtained as the molar extinction (εmol), the detection
limit and the range of detected concentrations.
In contrast to the anionic and nonionogenic
surfactants the micellar medium of cationic surfactant
(cetylpyridinium chloride) provided
a
complete
solubility of the hydrazone aci-form II. It seemed
expident to evaluate the solubility of hydrazone I in
the absence and in the presence of micelles of the
cationic surfactants (pH 13). The solubility of
hydrazone I evaluated by the isothermal saturation
method was 4.0 × 10–7 mol l–1 (7.05 × 10–5 g l–1) in
water and 2.5 × 10–5 mol l–1 (4.4 × 10–3 g l–1) in the
micelles of cetylpyridinium chloride. This finding
means that the solubility of hydrazone at the transfer
from water to the micellar medium increases ~60 times.
Increase in the aggregative stability of solutions was
observed (within 5 h). The homogenous solutions
obtained were intensely colored (λmax 470–530 nm,
Fig. 2) and stable during several hours. Solubilization
of the aci-form of hydrazones analogous to II occurs
evidently in the surface layer of the cationic micelles.
Detection limit is determined as the smallest
content of a substance which can be found in the
А
1.2
3
4
1
2
0.8
0.6
1
The increase in solubility of hydrophobic sub-
stances when the critical concentration of the micelle
formation is attained in the solutions of surfactants (the
solubilization) in many cases is accompanied by
formation of thermodynamically stable isotropic
solutions. This process is analogous to extraction. The
role of the second phase is played by the micelles of
surfactant (pseudophase). The solubilization is affected
by different factors like temperature, the nature of
surfactant and of the solubilized compound, presence
of alien electrolytes, the concentration of counterions,
etc. [14]. It is presumable that the sharp increase in the
solubility of hydrazone II in the micelles of cationic
0.4
0.2
0
400 440
480 520 560 600
640
λ, nm
Fig. 2. The electron absorption spectra of the system 2,4-
dinitrophenylhydrazine (1 × 10–5 M)–p-dimethylamino-
cynnamaldehyde (1 × 10–5 M)–cetylpyridinium chloride.
CCPC: (1) 1 × 10–4 M; (2) 2 × 10–4 M; (3) 6 × 10–4 M; (4) 8 ×
10–4 M. A reference solution is borate buffer (pH 13), l = 1 cm.
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906
DORONIN et al.
Table 2. Some characteristics of the system aromatic aldehyde–2,4-dinitrophehylhydrazine–cetylpyridinium chloride (pH 13).
εmol×104,
l mol–1cm–1
12.6
Detection limit
Range of detected
contents, μg ml–1
0.06–0.2
Aldehyde
λmax, nm
× 10–6, mol l-
p-Dimethylamino cynnamaldehyde
p-Dimethylamino benzaldehyde
Benzaldehyde
500
480
470
470
530
470
470
0.39
1.2
2.4
1.6
1.2
1.2
1.2
1.97
0.18–2.1
2.08
0.25–1.4
p-Methoxybenzaldehyde
p-Nitrobenzaldehyde
3.97
0.28–2.1
2.02
0.18–1.9
m-Nitrobenzaldehyde
2.02
0.18–2.0
p-Chlorobenzaldehyde
2.08
0.20–2.1
2,4-Disulfobenzaldehyde
480
1.87
1.3
0.28–2.3
sample by the given procedure with the given
confidential probability. The range of detected
concentrations is the range between the smallest and
the largest concentration of the given component. For
the aci-form of hydrazone of p-nitrobenzaldehyde the
red shift was observed due to maximum redistribution
of the electronic density in the molecule caused by the
pronounced induction (–I) and mesomeric (–C) effects,
and also the field effect (–F) of the nitro group in p-
position of the benzene ring.
These electronic effects caused by the dimethyl-
amino group and the vinyl fragment result in the
highest reactivity of p-dimethylaminocynnamaldehyde
among the aromatic aldehydes under study. They also
lead to the increase in εmol of the corresponding
hydrazone and the decrease in the detection limit of the
aldehyde.
Hence, micellar media of the cationic surfactants
favor the increase in solubility of the aci-forms of
hydrazones and their stabilization. The above-
mentioned effects can be used in the photometry of the
lagre number of carbonyl compounds (ketones,
aldehydes, and quinones) without using toxic solvents,
extraction, and prolonged heating.
Introduction of an electron-donating dimethylamino
group and a vinyl fragment in the molecule of
benzaldehyde (the case of p-dimethylaminocynnamal-
dehyde) not only increases the conjugation chain in the
molecule of the obtained hydrazone by redistribution
of the electronic density in the initial aldehyde (a
semiquinoid form [15]), but also leads to the 10-fold
increase in the εmol as compared to the other aldehydes
under investigation. In [16] quantum chemical
calculations were performed on the distribution of the
molecular electrostatic potential in the molecules of
benzaldehyde and some its derivatives including p-
dimethylaminobenzaldehyde and p-dimethylamino-
cynnamaldehyde. It was shown that the introduction of
dimethylamino group into the molecule of
benzaldehyde leads to the alteration in the molecular
electrostatic potential in the functional group of
aldehydes: An increase was found of the area of
negative molecular electrostatic potential around the
oxygen atom of the carbonyl group as well as of the
positive area of molecular electrostatic potential
around the carbonyl carbon atom. Therewith the area
of positive values of the molecular electrostatic
potential above the carbon atom of the carbonyl group
in the p-dimethylaminocynnamaldehyde is signif-
icantly larger than in the p-dimethylaminobenz-
aldehyde and benzaldehyde.
EXPERIMENTAL
The electron absorption spectra were registered on
a SF-46 spectrophotometer. The IR spectra were
obtained on a FSM 1201 Fourier spectrometer in
hexachlorobutadiene (4000–1800, 1500–1300 cm–1 and
in mineral oil (1300–400 cm–1). The derivatograms
were taken on an OD-103 derivatograph in air in the
temperature range 0–1000°C at heating rate 10°C/min.
pH values were measured on pH-121 and pH-673
devices. Starting 2,4-dinitrophenylhydrazine (pure,
TU-6-09- 2394-72), the aldehydes (p-, m-nitro, p-
chloro-, p-dimethylamino-, 2,4-disulfobenzaldehydes,
and p-dimethylaminocynnamaldehyde) were crystal-
lized from aqueous ethanol (melting points checked
[16]). Benzaldehyde and p-methoxybenzaldehyde were
distilled before use. Cetylpyridinium chloride mono-
hydrate, C21H38NCl · H2O (pure for analysis, TU-6-09-
15-121-74), sodium dodecylsulfate, C12H25OSO3Na
(pure, TU-6-09-07-1816-93, main substance content
82.4 1.3%0), and hydroxyethylated alkylphenol OP-
10, C14H23O(C2H4O)10H, (pure) were used as sur-
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EFFECT OF THE MICELLAR SURFACTANT NANOREACTORS
907
factants. The constant pH was maintained with the use
REFERENCES
of borate buffer solutions.
1. Brettle, R., Obshchaya organicheskaya khimiya
(Comprehensive Organic Chemistry), Moscow:
Khimiya, 1982, vol. 2, p. 488.
Synthesis of hydrazone from 2,4-dinitrophehyl-
hydrazine and p-dimethylaminocynnamaldehyde. A
weighed portion (0.0277 g) of 2,4-dinitrophenyl-
hydrazine was dissolved in distilled water at heating in
a 500 ml flask, and the solution obtained was acidified
with concentrated HCl to pH 1. A weighted portion p-
dimethylaminocynnamaldehyde (0.0492 g) was
dissolved analogously. The hot solutions of reactant
were mixed and heated at 80–90°C till complete
coagulation of the precipitate obtained. The reaction
mixture was thoroughly stirred and cooled. The
precipitate was filtered off on a frit and washed with
distilled water till the negative test for chloride ion
with silver nitrate. The hydrazone obtained was dried
at 110°C to remove the adsorbed moisture till the
constant weight. The yield of the product was 70%.
Found, %: C 57.46; H 4.82; N 19.71; O 18.01.
C17H17N5O4. Calculated, %: C 57.88; H 4.47; N 20.05;
O 17.60.
2. McMurry, J.E., Chem. Communs, 1968, no. 8, p. 443.
3. Kuznetsova, E.V., Tatarenko, S.A., Mil’kina, T.N.,
Morzhakova, T.M., Kudinova, L.M., and Batalin, O.A.,
Neftekhimiya, 1983, vol. 23, no. 5, p. 693.
4. Roper, K. and Zohn, H., Leder, 1992, vol. 43, no. 5,
p. 117.
5. Vinuelas Cobo, J.L., Rodriguez Roldan, A., Botas
Rabasa, M., and Garsia-Moreno del Rio, C., A
limentaria, 1996, vol. 34, no. 269, p. 67.
6. Znerek, G., Lyftmann, H., and Karst, U., Analyst., 1999,
vol. 124, no. 9, p. 1291.
7. Serikov, A.V., Berezkin, V.G., and Gogoman, I.V.,
Zavod. Laborat.: Diagnost. Mater., 2002, vol. 68, no. 9,
p. 9.
8. Tang, J., Wang, X., Fen, Y., Sheng, G., and Fu, J., Anal.
Chem., 2003, vol. 31, no. 12, p. 1468.
9. Fenaille, F., Tabet, J.-C., and Guy, P.A., Anal. Chem.,
2004, vol. 76, no. 4, p. 867.
Evaluation of solubility of hydrazone in alkaline
medium by isothermic saturation method. A
weighed portion of the hydrazone synthesized, 0.05–
0.1 g, was placed in a flask equipped with a glycerol
seal and a stirrer, and 10 ml of the borate buffer (pH
13) was added to it. Cetylpyridinium chloride, 0.6 ml
of 10–2 M solution, and 9.4 ml of the borate buffer was
added to create the micellar medium. The rotation rate
of the stirrer was chosen to provide the greater part of
the solid phase to be in the suspended state. The
establishing of the equilibrium in the heterogeneous
system was checked by sampling once in an hour in
the course of 6 h. The concentration of the hydrazone
aci-form in water and water–micellar media was
established using the corresponding calibration graphs.
For evaluation of concentration of the hydrazone aci-
form in the micelles of cetylpyridinium chloride the
sample was preliminary diluted 10 times.
10. Sekine, Y., Oikava, D., Saiton, K., and Asano, Y., J. Health
Sci., 2005, vol. 51, no. 6, p. 629.
11. Saczk, A.A., Okumura, L.L., De Olivera, M.F., Za-
noni, M.V.B., and Stradiotto, N.R., Anal. and Bioanal.
Chem., 2005, vol. 381, no. 8, p. 1619.
12. Zhang, H-J., Huang, J.-F., Wang, H., and Feng, Y.-Q.,
Anal. Chim. Acta, 2006, vol. 565, no. 2, p. 129.
13. Korenman, I.M., Fotometricheskii analiz. Metody
opredeleniya organicheskikh soedinenii (Photometric
Analysis. Methods of Evaluation of Organic Com-
pounds), Moscow: Khimiya, 1970.
14. Shinoda, K., Hakagava, T., Tamamusi, B., and Isemura, T.,
Kolloidnye poverkhnostno-aktivnye veshchestva (Col-
loid Surfactants), Moscow: Mir, 1966.
15. Gusakova, N.N., Teoreticheskie i prikladnye aspekty
primeneniya
v
fotometricheskom analize sistem
pervichnye aromaticheskie aldegidy (APAV Theoretical
and Applied Aspects of Use of the Aromatic Aldehyde
Anionic Surfactant Systems in Photometric Analysis),
Saratov: SGAU, 2002.
ACKNOWLEDGMENTS
The work was carried out with the financial support
of the Federal Agency of Science and Innovations
(grant no 2007-3-1.3-28-01-229).
16. Gordon, A. and Ford, P., Sputnik khimika (Chemist’s
Companion), Moscow: Mir, 1976.
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