Synthesis and Characterization of Fluorodinitrobenzenes with Tunable Melting Point: Potential Low Sensitive Energetic Plasticizer and Melt-Cast Carrier?

Article abstract of DOI:10.1002/cjoc.202000355

In order to explore the effects of fluoro substituents on the energy and safety of energetic compounds, a series of fluorodinitrobenzenes including 1,3-difluoro-2,4-dinitrobenzene (1), 1,5-difluoro-2,4-dinitrobenzene (2), 1,2,3-trifluoro-4,6-dinitrobenzne (3) and 1,3,5-trifluoro-2,4-dinitrobenzene (4) were prepared. All the compounds were fully characterized. The structures of 2 and 3 were further confirmed by single crystal X-ray diffraction analysis. The results show that these compounds exhibit comparable detonation properties (D = 6703-6978 m·s^–1, and p = 21.3—23.7 GPa) to those of 2,4,6-trinitrotoluene (TNT) due to the significantly increased density of fluorine introduced. Low sensitivity (IS > 40 J, and FS > 360 N) of these compounds along with different melting points make them potential candidates for different allocation. Among them, 1 and 4 with the melting point of 42.5 °C and 55.2 °C, respectively, show promise for application in the field of energetic plasticizer. Compounds 2 and 3 are potential low sensitive melt-cast carrier due to their similar melting point and superior detonation performance to that of TNT.

Full text of DOI:10.1002/cjoc.202000355

Chinese Journal
of Chemistry
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Accepted Article
Title: Synthesis and Characterization of Fluorodinitrobenzenes with Tunable
Melting Point: Potential Low Sensitive Energetic Plasticizer and Melt-cast Carrier
Authors: Yunlu Li, Peng Chen, Yan Liu, Ping Yin, Chunlin He,* and Siping Pang*
This manuscript has been accepted and appears as an Accepted Article online.
This work may now be cited as: Chin. J. Chem. 2020, 38, 10.1002/cjoc.202000355.
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Chinese Journal
of Chemistry
Energetic materials, Fluorine, Synthesis, Plasticizer, Melt-cast carrier
Report
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中
国 化 学 - An International Journal
Synthesis and Characterization of Fluorodinitrobenzenes with Tunable
Melting Point: Potential Low Sensitive Energetic Plasticizer and Melt-
cast Carrier
Yunlu Li,a,b,c Peng Chen,a,b Yan Liu,a,b Ping Yin,a,b Chunlin He,*,a,b,c and Siping Pang*,a
a School of Materials Science & Engineering, Beijing Institute of Technology, Beijing, 100081, China.
b Experimental Center of Advanced Materials, School of Materials Science & Engineering, Beijing Institute of Technology, Beijing 100081, China.
c Beijing Institute of Technology Chongqing Innovation Center, Chongqing, 401120, China.
Cite this paper: Chin. J. Chem. 2019, 37, XXX—XXX. DOI: 10.1002/cjoc.201900XXX
Summary of main observation and conclusion In order to explore the effects of fluoro substituents on the energy and safety of energetic compounds, a
series of fluorodinitrobenzenes including 1,3-difluoro-2,4-dinitrobenzene (1), 1,5-difluoro-2,4-dinitrobenzene (2), 1,2,3-trifluoro-4,6-dinitrobenzne (3) and
1,3,5-trifluoro-2,4-dinitrobenzene (4) were prepared. All the compounds were fully characterized. The structures of 2 and 3 were further confirmed by
single crystal X-ray diffraction analysis. The results show that these compounds exhibit comparable detonation properties (D=6703-6978 m·s-1, and p=21.3-
23.7 GPa) to that of 2,4,6-trinitrotoluene (TNT) due to the significantly increased density of fluorine introduced. Low sensitivity (IS>40 J, and FS>360 N) of
these compounds along with different melting points make them potential candidates for different allocation. Among them, 1 and 4 with the melting point
of 42.5 ℃ and 55.2 ℃, respectively, show promise for application in the field of energetic plasticizer. Compound 2 and 3 are potential low sensitive melt-
cast carrier due to their similarity melting point and superior detonation performance to that of TNT.
A plasticizer enhances fluidity or plasticity of propellant when
adding as a part of formulation. Energetic plasticizers are used to
Background and Originality Content
Continuous efforts had been put into the synthesis of energetic
improve physical properties, to act as a fuel and to improve the
compounds with excellent performance in the recent decades.[1-5]
overall energy level of a formulation. A preferred energetic
It has become an important research field to obtain composite
plasticizer must possess a good density, reasonable sensitivity, low
energetic materials with tailored properties and functions such as
melt-cast explosive and solid propellants through formulation
design.[6-7]
[15]
chemical reactivity, and reasonable low melting point.
At
present, oily liquid nitroglycerin (NG)[16] is one of the most popular
nitrate ester based plasticizer. Because of its high sensitivity and
phase transitions in manufacturing and application, NG is
extremely dangerous in any case. Some alternative energetic
plasticizer based on nitroxyalkyl-, azidoalkyl-, or N-substituted
nitro-based heterocycles were prepared, while the concerns
towards the stability and safety issues still exist. [17-20]
Melt-cast explosive is a kind of composite explosive,
manufactured by adding solid phase high-energy explosives such
as 1,3,5-trinitro-1,3,5-triazinane (RDX),[8] 1,3,5,7-tetranitro-
1,3,5,7-tetrazinane (HMX)[9] or hexanitrohexaazaisowurtzitane
(HNIW)[10-12] into molten liquid phase carrier such as 2,4,6-
trinitrotoluene (TNT), which is widely used in grenades, mortars
and landmines to achieve efficient damage. Since the content of
melt-cast carrier usually exceeding 30%, its energy and safety
properties directly affect the application of melt-cast explosive. An
ideal melt-cast carrier is expected to have a low-vapor pressure
and melting point between 70 – 120 °C, a large gap between its
In designing an optical energetic compound, understanding
how chemical functional groups affect physical properties,
detonation properties and stability for impact and friction of
designed materials becomes imperative. Generally, introducing
-
some high-energy groups such as -NO2, -NHNO2, -C(NO2)2 , -
C(NO2)3 and -N3, etc. to the molecular framework, can effectively
improve the energy level of energetic compounds by enhancing
the density and oxygen balance, but at the same time, their impact
sensitivity also increases.[21-26] Although some strategies including
introducing hydrogen bonds into and between molecules can
efficiently improve the safety performance of energetic
compounds, it often requires introducing -NH2, -CH3 or other
groups into molecules, which will lead to the decrease of energy
melting point and decomposition temperature, a high density and
[13]
low sensitivity and a “greener” synthesis.
Due to the high
toxicity and high sensitivity, TNT, a traditional melt-cast carrier, is
gradually being replaced by 2,4-dinitroanisole (DNAN)[14]. However,
DNAN, with a density of 1.52 g·cm-3, and detonation velocity of
5670 m·s-1, is less powerful than TNT. Therefore, it motivates us to
the research of novel melt-cast carrier.
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level.[27]
Results and Discussion
Synthesis and X-ray crystallography
Fluorination, as an important and effective chemical
modification method, has been widely studied in the field of
materials and chemistry.[28-30] Because of the small volume of
fluorine atom, replacing hydrogen atoms with fluorine atoms can
significantly increase the molecular density.[31-32] The strong
electronegativity of fluorine atoms also strengthens the
interactions between molecules, which is conducive to improving
the stability of molecules and the stacking density of crystal.[33-34]
Moreover, the introduction of fluorine atoms into aluminum-
containing composite propellant can promote the reaction
between aluminum and fluorine to produce gaseous AlF3, which
can not only restrain the agglomeration of aluminum on the
combustion surface, but also improve the combustion efficiency of
aluminum as well as heat of combustion.[35] Therefore, fluorine-
containing energetic materials have gained increasing attentions
from the researchers.
We started with the synthesis of 1,3-difluoro-2,4-
dinitrobenzene (1) by reacting 1,3-difluoro-2-nitrobenzene (R1)
with 98% nitric acid and 98% sulfuric acid at 80 ℃ for two hours,
and the yield of compound 1 reached 87.7% after optimized
synthesis conditions. Compound 2 which is widely used in
supramolecular field,[41] was prepared by starting from
commercially available 1,3-difluoro-4-nitrobenzene (R2) instead of
1,3-difluorobenzene.[42] When replacing the nitration agent of
potassium nitrate and sulfuric acid with the mixed acid, a shorter
reaction time was achieved for preparing compound 3 which was
reported as an intermediate in the synthesis of heat resistant 2-
fluoro-1,3-diamino-4,6-dinitrobenzene.[43]
dinitrobenzene (4) had been reported in the literature with a yield
of 58% by nitrating 1,3,5-trifluorobenzene in 3 days.
1,3,5-trifluoro-2,4-
[44-45]
In recent years, some fluorine based energetic compounds
have been reported. Fluorine atoms were introduced into the
molecular framework in terms of -NF2, -CF3, -CF(NO2)2, and -
CF2(NO2) groups to improve the density, thermal stability and
safety of the energetic compounds (Figure 1).[36-38] Our previous
works also discussed the improvement in energy and safety
performance brought by its introduction of C(N)-F groups.[39-40]
However, few studies were observed on relationship between
fluorination and the affections of physical properties, especially
the melting point. While the appropriate melting point is of great
significance of the design and synthesis of novel low-melting
energetic compounds as candidates for energetic plasticizers and
melt-cast carriers.
Alternatively, by starting from commercially available 1,3,5-
trifluoro-2-nitrobenzene (R4) and reacting with mixed acid
between 60-80 ℃, an improved yield of 84.1% for compound 4 was
obtained. When the reaction temperature is lower than 60 ℃, a
longer reaction time will be needed. For example, when the molar
ratio of nitric acid to raw material is 12.5 to 1 and reacting at 50 ℃,
it takes 10 hours to complete the reaction, while the reaction time
can be reduced to one hour and half if the reaction temperature
was increased to 80 ℃. The structures of all prepared compounds
were confirmed by IR, NMR, and EA.
F
F
N
F
O2
NO2
N
F
O2
N
N
N
N
NO2
NO2
N
N
1
R1
F
3C
N
N
N
O
O
N
N
N
N
N
N
N
CF3
NO2
NO2
F
F
F
F
N
O2
NF2
N
F
O2
N
O2
N
O2
NO2
R2
F
2
F
NO2
NO2
F
N
O2
F
N
N
F
NO2
HN
N
NH
N
O
N
F
N
N
O2
N
N
HNO
N
3/H2SO4
N
N
O
F
℃
NO2
N
N
N
60-80
F
F
F
F
F
O
O
Figure 1 The reported fluorine-based energetic compounds.
N
O2
N
O2
NO2
R3
F
3
F
In this work, we synthesized a series of fluorodinitrobenzenes
and their structures were fully characterized. The heat of
formation of these compounds were calculated based on Gaussian
program using DFT method and detonation properties were
calculated by EXPLO5 v6.04, and further experimental
measurements of thermal properties, impact and friction
sensitivity were carried out. The influence of introducing C-F group
into nitrobenzene on the structure and performance of energetic
compounds was discussed.
N
F
O2
N
F
O2
NO2
F
F
R4
4
Scheme 1 Synthesis of compounds 1 - 4.
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Suitable crystals of compounds 2 and 3 for X-ray crystal
Figure 2 (a) Molecular structure of 2. (b) Pachking diagram of 2.
structure determination were obtained by dissolving 2 or 3 in
methanol solution and let the solvent slowly evaporate,
transparent colorless crystals were obtained for X-ray single crystal
test. The detailed information about the structures is provided in
the ESI. Crystal data showed that the crystal density of 2 and 3 is
1.820 g·cm-3and 1.891 g·cm-3 at room temperature, respectively,
which is 0.15 g·cm-3 and 0.32 g·cm-3 higher 1,3-dinitrobenzene
(DNB, 1.575 g·cm-3),[46] indicating that the introduction of fluorine
atoms significantly increases the density of molecules.
Single crystal structure of 2 was shown in Figure 2. The Fluorine
atom in 2 forms C-F…H hydrogen bond with other two molecules,
with the F-H bond lengths being 2.751 Å and 3.483 Å (Figure 2(a)).
While the intramolecular F-O halogen-like bond formed between
the fluorine atom and the o-nitro O atom with the F-O bond length
being 2.644 Å. This pattern of weak interaction causes the crystals
to accumulate in waves like Figure 2(b). Moreover, the diversity of
weak interactions will enhance the stability of the compound 2.
While the interactions in 3 are much more complex than that
in 2 shown in Figure3(a). The fluorine atom in 3 forms a complex
weak interaction with O atom and H atom of the other three
molecules respectively. The F-H bond, with a length of 2.638 Å, is a
moderately strong hydrogen bond, while the two F-O bonds, with
length of 3.089 Å and 3.436 Å, respectively, are halogen-like bonds
formed due to the strong polarization of C-F bond in 3. The
combination of those complex weak interactions results in the
crystal stacking structure of 3 in a cross-stacking manner showing
in Figure 3(b).
Figure 3 (a) Molecular structure of 3. (b) Pachking diagram of 3.
Perhaps because of the high solubility or the low melting point,
no suitable crystals of 1 and 4 for single X-ray diffraction were
obtained in various solvents including alcohols, esters, ketones or
benzene.
Thermal performance
Thermal stability is an important property for energetic
materials, the thermal behavior of compounds 1, 2, 3, and 4 was
determined with differential scanning calorimeter (DSC) measured
at a heating rate of 10 ℃·min-1. The tends of DSC curves for these
compounds is consistent, and all of the prepared compounds has a
low melting point as well as an exothermic peak (Figure 4).
Compounds 1 and 4 possess the similar melting point of 42.5 ℃
and 55.2 ℃, respectively, which is close to that of 2-
(methyl(nitro)amino)ethyl nitrate (Me-NENA, melting point of
38 ℃)[47] and tetrazido pentaerythritol (TAPE, melting point of
48 ℃)[48], respectively. Compound 2 and 3 have a close melting
point of 76.7 ℃ and 72.4 ℃, respectively, which are very close to
that of TNT (melting point of 80.4 ℃). The significant differences in
the melting point and thermal decomposition temperature of
these compounds make them possible to be used as potential
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energetic plasticizer or melting-cast carrier. The figures of the DSC
test and the integral of heat flow are shown in ESI.
DNB
TNT
89.0
80.4
1.575
1.654
5501.6
6809.0
12.4
18.7
--
--
15
353
It is worth noting that the thermal properties of these
compounds are closely related to their structure. The introduction
of fluorine atom does result in a lower melting point than that of
DNB. Moreover, the number and substituted positions of fluorine
atoms also resulting the variety of their melting point in a wide
range. Among the four compounds, the most asymmetric structure
of 1 with the fluorine atoms and nitro groups occupying 1-, 3- sites
and 2-,4- sites, respectively, giving the lowest melting point. The
introduction of one more fluoro group in 5-position in 4 improves
the possibility of forming more halogen bonds in the structure
which resulting a higher melting point. Compound 2 which has the
most symmetrical structure possesses a highest melting point of
76.7 °C.
d
a Melting point. b Density (gas pycnometer, 25℃). c Detonation velocity.
Detonation pressure. e Impact sensitivity. f Friction sensitivity.
The substitution of two protons by F atoms in DNB, leads to the
formation of compound 1 and 2 which possesses a density of 1.828
g·cm-3 and 1.808 g·cm-3, respectively, are greatly improved by
comparing to that of DNB. While if three H atoms in DNB were
substituted by F atoms, the density increased significantly, from
1.575 g·cm-3 to 1.887 g·cm-3 (3) and 1.872 g·cm-3 (4), respectively.
However, the decreases of heat of formation was obtained as the
numbers of fluoro-substitution increases as the HOF of 1 - 4 were
calculated to be -261.79 kJ mol-1, -278.16 kJ mol-1, -431.79 kJ mol-1
and -436.62 kJ mol-1, respectively. As a result, the calculated
detonation velocity of 1 and 2 are 6978.0 m·s-1 and 6906.9 m·s-1,
and detonation pressure of 23.7 GPa and 23.0 GPa, respectively.
Compound 3 and 4 which possess more fluorine atoms in the
molecule gives lower detonation velocity of 6746.3 m·s-1 and
6703.2 m·s-1, and detonation pressure of 21.7 GPa and 21.3 GPa.
Superior to that of DNB and being comparable to that of TNT.
Application potential
With low melting point, better thermal stability, low impact
and friction sensitivity, and comparable detonation properties to
TNT, these fluorodinitrobenzene compounds are promising to be
used in composite energetic materials. Therefore, we designed
some new formulations to investigate their application potential.
Table 2 Formulations and properties of designed solid propellants.
[d]
Formula. HTPB[a]
AP[b]
Al[c] Bu-NENA
1
4
ISP
[s]
Figure 4 DSC curves of the 1, 2, 3, and 4.
F1
F2
F3
12%
12%
12%
65%
65%
65%
15%
15%
15%
8%
-
-
8%
-
-
-
266.3
262.2
262.0
Detonation and safety performance
-
8%
Detonation velocity and detonation pressure are the two
important indicators to evaluate the energy level of energetic
compounds, which are related to the density, oxygen balance and
heat of formation (HOF).[49] Therefore, in designing novel energetic
materials, improving the density, heat of formation and oxygen
balance are important approach to obtain high-energy density
material with excellent detonation performance.[50] Based on the
measured densities by using a gas pycnometer (25 ℃) and
calculated HOF by DFT method, the detonation properties of these
compounds were evaluated via the EXPLO5 6.04 program (Table
1).[50]
a
b
c
Hydroxyl terminated polybutadiene.
Aluminum. d Specific impulse.
Ammonium perchlorate.
Table 3 Formulations and properties of designed melting-cast explosives.
Formula. TNT
RDX
2
3
D[a]
p[b]
[GPa]
[m·s-1]
F4
F5
F6
40%
60%
60%
60%
-
40%
-
-
-
8002.5
8200.5
8241.5
27.1
30.5
32.8
-
-
40%
a Detonation velocity. b Detonation pressure.
Table 1 Physiochemical properties of prepared fluorodinitrobenzene
compounds.
Compound 1 and 4 were added as energetic plasticizers to
aluminum-containing composite propellant to Bu-NENA, and
obtain formulation F2 and F3. The calculated results show that the
Specific impulse (Isp) of F2 and F3 is 262.2 s and 262.0 s, respectively,
which is comparable to 266.3 s of F1 (Table 2). Compound 2 and 3
were used as melt-cast carrier to replace TNT in classical B
Explosive (40% TNT and 60% RDX) to obtain formulation F5 and F6.
The results show that the detonation velocity of F5 and F6 is 8002.5
m·s-1 and 8241.5 m·s-1, respectively, and detonation pressure is
[a]
Tm
ρ[b]
[g·cm-3]
D[c]
[m·s-1]
p[d]
[GPa]
IS[e]
[J]
FS[f]
[N]
Compd.
[℃]
1
2
3
4
42.5
76.7
72.4
55.2
1.828
1.808
1.887
1.872
6978.0
6906.9
6746.3
6703.2
23.7
23.0
21.7
21.3
>40
>40
>40
>40
>360
>360
>360
>360
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30.5 GPa and 32.8 GPa, respectively, which are both higher than
that of F3 (Table 3). These results show that the prepared
fluorodinitrobenzene compounds have good application potentials.
elemental analysis calcd (%) for C6H2N2O4F2 (204.09), C 35.31%, H
0.99%, N 13.73%; found: C 35.28%, H 0.93%, N 13.85%.
1,5-difluoro-2,4-dinitrobenzene (2) To a stirred solution of 98%
HNO3 (3.2 g, 50 mmol) in 98% H2SO4 (3.6 g, 40 mmol) was slowly
added 2,4-difluoronitrobenzene (0.636 g, 4 mmol). The reaction
solution was stirred at 80 ℃ for 2 h. The reaction mixture was then
poured into ice water, the solid formed was collected by filtration,
washed with water, and recrystallized in methanol to obtain white
Conclusions
By nitrating of commercially available fluoronitrobenzene
precursors R1, R2, R3 and R4 using mixed acid, a series of fluoro-
dinitrobenzene energetic compounds were prepared. The
existence of F-H hydrogen bonds, F-O halogen bonds among
molecules is beneficial to improve the stability of molecules. The
tuning of melting point for compound 1 – 4 can be achieved by
control the number and substituted position of fluoro group.
Meanwhile, the introduction of fluorine atoms increases the
molecular density but decreases the heat of formation. The
calculated detonation velocity and pressure of the obtained
compounds indicates that they have an energy level comparable to
TNT but a lower sensitivity than TNT. The close melting point of
compound 2 (76.7 ℃) and 3 (72.4 ℃) to that of TNT (80.4 ℃) makes
them competitive as melt-cast carriers to the replacement of TNT.
While lower melting point of compound 1 (42.5 ℃) and 4 (55.2 ℃)
close to that of Me-NENA (38 ℃) makes them potential candidates
for energetic plasticizer.
1
solid of 2 with yield of 89.2%. H NMR (400 MHz, DMSO-d6):
δ=8.16-8.22 (t, J=12 Hz, 1H), 8.91-8.95 (t, J=8 Hz, 1H) ppm; 13C NMR
(100 MHz, DMSO-d6): δ=109.78-110.31 (t, J=26 Hz, 1C), 125.10,
156.70, 159.57 ppm; 19F NMR (376 MHz, DMSO-d6): δ=-103.20
ppm. IR(KBr): ν=3071.76, 1616.14, 1545.76, 1349.39 cm-1;
elemental analysis calcd (%) for C6H2N2O4F2 (204.09), C 35.31%, H
0.99%, N 13.73%; found: C 35.15%, H 0.89%, N 13.83%.
1,2,3-trifluoro-4,6-dinitrobenzne (3) To a stirred solution of 98%
HNO3 (3.2 g, 50 mmol) in 98% H2SO4 (3.6 g, 40 mmol) was slowly
added 1,2,3-trifluoro-4-nitrobenzene (0.708 g, 4 mmol). The
reaction solution was stirred at 80 ℃ for 2 h. The reaction mixture
was then poured into ice water, the solid formed was collected by
filtration, washed with water, and recrystallized in methanol to
1
obtain white solid of 3 with yield of 84.2%. H NMR (400 MHz,
DMSO-d6): δ=8.80-8.84 (m, J=16 Hz, 1H) ppm; 13C NMR (100 MHz,
DMSO-d6): δ=117.93, 121.03, 132.92, 180.24 ppm; 19F NMR (376
MHz, DMSO-d6): δ=-150.38, -126.90 ppm. IR(KBr): ν=3097.47,
1641.48, 1551.09, 1350.49, 1311.47 cm-1; elemental analysis calcd
(%) for C6HN2O4F3 (222.08), C 32.45%, H 0.45%, N 12.61%; found: C
32.61%, H 0.37%, N 12.62%.
Experimental
General methods
1H, 13C and 19F NMR spectra were recorded on a 400 MHz
(Bruker ACANCE III 400) nuclear magnetic resonance spectrometer
by using DMSO-d6 as the solvent. DSC are performed at 10 ℃ min-
1 in a closed, gold-plated stainless steel, high-pressure crucible with
a nitrogen flow of 30 mL·min-1 (Mettler Toledo DSC-3). FT-IR
spectra were recorded on a Bruker VERTEX 70 FT-IR instrument at
room temperature. Element analysis of C/H/N were tested with an
Elementar Vario Micro Cube Auto Analyzer. The impact sensitivity
and friction sensitivity were measured using the standard BAM
methods.
1,3,5-trifluoro-2,4-dinitrobenzene (4) To a stirred solution of
98% HNO3 (3.2 g, 50 mmol) in 98% H2SO4 (3.6 g, 40 mmol) was
slowly added 1,3,5-trifluoro-2-nitrobenzene (0.708g, 4mmol). The
reaction solution was stirred at 80 ℃ for 2 h. The reaction mixture
was then poured into ice water, the solid formed was collected by
filtration, washed with water, and recrystallized in methanol to
1
obtain white solid of 4 with yield of 84.1%. H NMR (400 MHz,
DMSO-d6): δ=8.13-8.19 (td, J=12, 4 Hz, 1H) ppm; 13C NMR (100
MHz, DMSO-d6): δ=104.32-104.89 (td, J=26, 4 Hz, 1C), 148.58,
151.25, 155.16, 157.83ppm; 19F NMR (376 MHz, DMSO-d6): δ=-
121.32, -106.36 ppm. IR(KBr): ν=3118.72, 2090.07, 1630.35,
1551.28, 1347.40, cm-1; elemental analysis calcd (%) for C6HN2O4F3
(222.08), C 32.45%, H 0.45%, N 12.61%, found: C 32.54%, H 0.39%,
N 12.62%.
X-ray crystallography
Data collection for 2 and 3 was performed on Mercury CCD and
Saturn 724 CCD diffractometer, respectively, by using graphite
monochromated MoKa radiation. The raw data is refined by
SHELXL-97 and SHELXS-97 program.[51] CCDC-1201170 (2) and
1874978 (3) contains the details of the structures of 2 and 3.
Supporting Information
The supporting information for this article is available on the
WWW under https://doi.org/10.1002/cjoc.2018xxxxx.
Synthesis
1,3-difluoro-2,4-dinitrobenzene (1) To a stirred solution of 98%
HNO3 (3.2 g, 50 mmol) in 98% H2SO4 (3.6 g, 40 mmol) was slowly
added 2,6-difluoronitrobenzene (0.636 g, 4 mmol). The reaction
solution was stirred at 80 ℃ for 2 h. The reaction mixture was then
poured into ice water, the solid formed was collected by filtration,
washed with water, and recrystallized in methanol to obtain white
Acknowledgment
Authors are grateful for the support of the National Natural
Science Foundation of China (Grant Nos. 21702017, 21875020) and
SKLST (BIT) QNKT18-03.
1
solid of 1 with yield of 87.7%. H NMR (400 MHz, DMSO-d6):
δ=7.72-7.78 (td, J=12, 4 Hz, 1H), 8.57-8.63 (td, J=8, 4 Hz, 1H) ppm;
13C NMR (100 MHz, DMSO-d6): δ=113.78-114.04(dd, J=21, 4 Hz, 1C),
130.95-131.08(dd, J=12, 2, 1C), 147.87, 150.64, 155.42, 158.09
ppm; 19F NMR (376 MHz, DMSO-d6): δ=-122.45, -107.90 ppm.
IR(KBr): ν=3114.18, 1622.70, 1540.10, 1483.10, 1348.17 cm-1;
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Entry for the Table of Contents
Page No.
Synthesis
and
Characterization
of
Fluorodinitrobenzenes with Tunable Melting
Point: Potential Low Sensitive Energetic
Plasticizer and Melt-cast Carrier
The melting point and detonation performances of fluorodinitrobenzenes can be finely tuned by
controlling the number and substitute position of fluoro group in 1,3-dinitrobenzene. The prepared
fluorodinitrobenzenes show great potential as energetic plasticizer or melt-cast carrier.
Yunlu Li, Peng Chen, Yan Liu, Ping Yin, Chunlin
He*and Siping Pang*
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© 2019 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2019, 37, XXX－XXX
This article is protected by copyright. All rights reserved.