Synthesis of 2,4-dinitrophenol

Article abstract of DOI:10.1134/S1070427212100163

New highly selective method is suggested for synthesis of 2,4-dinitrophenol by nitration of phenol with nitric acid in an aqueous-alcoholic medium at the boiling point of the reaction mixture. The yield of 2,4-dinitrophenol is as high as 80%. Pleiades Publishing, Ltd., 2012.

Full text of DOI:10.1134/S1070427212100163

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 10, pp. 1577−1580. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © Yu.G. Khabarov, D.E. Lakhmanov, D.S. Kosyakov, N.V. Ul’yanovskii, 2012, published in Zhurnal Prikladnoi Khimii, 2012, Vol. 85,
No. 10, pp. 1644−1647.
ORGANIC SYNTHESIS
AND INDUSTRIAL ORGANIC CHEMISTRY
Synthesis of 2,4-Dinitrophenol
Yu. G. Khabarov, D. E. Lakhmanov, D. S. Kosyakov, and N. V. Ul’yanovskii
Lomonosov Northern (Arctic) Federal University, Arkhangelsk, Russia
e-mail: khabarov.yu@mail.ru
Received May 10, 2012
Abstract—New highly selective method is suggested for synthesis of 2,4-dinitrophenol by nitration of phenol
with nitric acid in an aqueous-alcoholic medium at the boiling point of the reaction mixture. The yield of 2,4-di-
nitrophenol is as high as 80%.
DOI: 10.1134/S1070427212100163
2,4-Dinitrophenol is an important product of organic
synthesis used as means of corrosion protection of metals
[1], styrene polymerization inhibitor [2], antiseptic for
wood impregnation [3], and raw material for synthesis
of aromatic amino and nitro derivatives [4–6], dyes [7],
and chemicals for agriculture [8, 9].
By the nitration reaction, 2,4-dinitrophenol can
be synthesized using the classical nitrating mixture
[14]. The reaction product is dark red oil. After the
reaction product is purified with bone coal, the yield of
2,4-dinitrophenol is 65%.
A method has been suggested for synthesis of mono-
and dinitrophenol, in which sodium nitrite, oxalic
acid, and wet silicon dioxide are used. The reaction is
performed in methylene chloride [15].
The main method for obtaining 2,4-dinitrophenol is
by nitration of benzene, phenol, or mononitrophenol;
it is also synthesized by alkaline hydrolysis of
2,4-dinitrochlorobenzene.
Nitration of phenol with liquid N2O4 yields
2,4-dinitrophenol [16]. The expenditure of N2O4
is 4–6 mL g–1 phenol. It is recommended to purify
2,4-dinitrophenol by heating its alcoholic solution with
bone coal. The yield of 2,4-dinitrophenol is 76%.
2,4-Dinitrophenol is produced from benzene via
oxidative nitration with nitric acid in the presence of
mercury(II) hydroxide and a minor addition of sodium
nitrite. The yield of the product is 56.8% [10].
Another method for oxidative nitration of benzene
consists in bubbling of air or nitrose gases through
a nitric acid solution of mercury(II) nitrate, heated to
above 40°C. 2,4-Dinitrophenol with a melting point of
about 105°C has been produced by this technique [11].
2,4-Dinitrophenol is formed from sodium
nitromalonic aldehyde monohydrate and 1-nitro-2-
propanone via cyclodehydration in an alkaline medium
at room temperature in the course of 18 h. A purification
by column chromatography (SiO2; CH2Cl2) yielded
440 mg of pale yellow 2,4-dinitrophenol from 2 g of
sodium nitromalonic aldehyde monohydrate and 1.18 g
of 1-nitro-2-propanone [17].
A synthesis of 2,4-dinitrophenol has been described
in which nitrosophenol is produced from phenol and
then is subjected to oxidative nitration with nitric
acid at 90°C in the course of 1.5 h [12]. The yield of
2,4-dinitrophenol is 79%.
Thus, a large number of multistage labor-
consuming methods have been developed for synthesis
of 2,4-dinitrophenol. The goal of our study was to
develop a new high-selectivity method for synthesis
of 2,4-dinitrophenol, based on the reaction of phenol
2,4-Dinitrophenolisproducedfrom2,4-dinitrochloro-
benzene by the reaction of nucleophilic substitution
[13]. The reaction is performed in an alkaline medium at
a temperature of 95–97°C in the course of 3.5 h.
1577

1578
KHABAROV et al.
nitration with nitric acid in an aqueous-alcoholic
medium.
acetonitrile in a 0.5% aqueous solution of HCOOH
served as eluent. The flow rate was 0.4 mL min–1. The
HPLC data indicate that the preparation is an impurity-
free individual substance.
EXPERIMENTAL
The melting point (104.8°C) was determined with
a DSC Q2000 differential scanning calorimeter (TA
Instruments, United States).
We used for synthesis freshly distilled crystalline
phenol, concentrated nitric acid of chemically pure grade
(concentration 65%), and rectified ethanol (ethanol
content 95.3%).
The elemental composition was determined with
a EuroEA-3000 CHNS-analyzer (EuroVector, Italy).
Found (%): C 39.3 ± 1.1, H 2.13 ± 0.06, N 17.1 ± 0.5.
Calculated (%): C 39.13, H 2.17, N 15.2.
2,4-Dinitrophenol. A 2.5-g portion of phenol and
an aqueous-ethanolic solution of nitric acid, prepared
from 12.5 mL of concentrated nitric acid and 50 mL of
ethanol, was mixed in a round-bottomed flask.
The elemental composition of the synthesized
2,4-dinitrophenol coincides with that theoretically
predicted.
The reaction mixture was heated in an installation
with a reflux for 0.5–2 h. Then, approximately 50 mL
of a liquid was obtained by vacuum distillation. The
residue was transferred to a cup. The product crystallized
as yellow crystals. The crystals were washed with cold
water and dried in a vacuum-desiccator.
An electronic absorption spectrum of 2,4-dinitro-
phenol in a 2 M NH4OH solution was recorded in the
spectral range 200–500 nm with a Shimadzu UV1650
PC spectrophotometer (Fig. 1). Results of three
parallel measurements were used to calculate the molar
extinction coefficients at wavelengths corresponding
to absorption peaks (see table). These data pint to
a good reproducibility of the electronic spectra, and
the calculated extinction coefficients coincide with the
values reported in [18].
It was found that the yield of the product little depends
on the reaction duration. It was 4.8, 4.8, 4.7, and 4.8 g
at reaction durations of 0.5, 1, 1.5, and 2 h, respectively,
which is close to the theoretical value (4.89 g).
To be purified, 2,4-dinitrophenol was dissolved
in a hot 1 M solution of NaOH and 16% activated
carbon was added. In 5–10 min, the activated carbon
was separated by filtration. The filtrate was cooled
and acidified with hydrochloric acid to pH 2–3. The
precipitated light yellow crystals were separated from
the solution by vacuum-filtration and dried. The yield
upon the purification was 80% relative to the mass of the
product taken for recrystallization.
An IR spectrum was recorded with a Vertex IR
Fourier spectrometer (Bruker, Germany) by the method
of attenuated total internal reflection method (diamond
ATIR crystal, resolution 4 cm–1). The IR spectrum of
the synthesized 2,4-dinitrophenol (Fig. 2, spectrum 1)
coincides with spectrum 2 from the General library
database of IR spectra.
Chromato-mass-spectrometric
studies
were
A chromatographic analysis by reverse-phase HPLC
was made on a Zorbax Eclipse Plus C18 150 × 3 mm,
3.5 μm (Agilent, United States). A 40% solution of
performed on an LCMS-2020 liquid chromato-mass-
spectrometer (Shimadzu, Japan). The mass-detector
operated in the negative APCI (atmospheric pressure
Molar extinction coefficients of 2,4-dinitrophenol
Extinction coefficient, M–1 cm–1
λ, nm
Standard
deviation
Variation
coefficient
ε1
ε2
ε3
εav
ε [18]
–
220
256
360
395
12.7
7.2
12.4
7.1
12.4
7.0
12.5
7.1
0.2
0.1
0.3
0.3
1.3
1.9
2.7
2.5
7
12.6
10.6
12.5
10.4
12.0
10.1
12.4
10.4
13
10
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 85 No. 10 2012

SYNTHESIS OF 2,4-DINITROPHENOL
1579
D
Fig. 3. Mass spectrum of 2,4-dinitrophenol. (I) Intensity and
(m/z) mass-to-charge ratio.
CONCLUSIONS
λ, nm
A new selective method for synthesis of 2,4-dini-
trophenol in high yield was developed. The method is
based on nitration of phenol with nitric acid in an aque-
ous-alcoholic medium.
Fig. 1. Electronic spectrum of 2,4-dinitrophenol in a 2 M
solution of ammonia. 2,4-Dinitrophenol concentration
0.065 mM. (D) Optical density and (λ) wavelength.
ACKNOWLEDGMENTS
T
The study was carried out at the Center for Collective
Use, Research Association Arktika [Lomonosov
Northern (Arctic) Federal University] under the finan-
cial support from the Ministry of Education and Science
of the Russian Federation.
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ν, cm–1
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Fig. 2. IR spectra of 2,4-dinitrophenol. (T) Transmission
and (ν) wave number. (1) Synthesized preparation and (2)
spectrum from the General library IR spectral database signed
by Bruker Optic.
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The mass spectrum in Fig. 3 shows lines of the
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183), and dehydroxylated anion of 2,4-dinitrophenol
(m/z = 167), i.e., the product hardly contains any
impurities.
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