Nitramino- and Dinitromethyl-Substituted 1,2,4-Triazole Derivatives as High-Performance Energetic Materials

Article abstract of DOI:10.1002/chem.201701407

Since highly nitrated nitrogen-rich heterocycles are important motifs in high energy density materials, extensive studies for the development of such novel molecules have been underway. A highly energetic moiety, 3-dinitromethyl-5-nitramino-1,2,4-triazole, which consists of a triazole ring, and nitramino and dinitromethyl groups, has been designed and synthesized. By pairing with nitrogen-rich cations, several ionic derivatives were obtained. Theoretical and experimental studies show that the hydroxylammonium salt (7) is highly dense, and has excellent detonation performance with acceptable thermal stablity and sensitivities, which are superior to those of RDX.

Full text of DOI:10.1002/chem.201701407

A Journal of
Accepted Article
Title: Nitramino- and dinitromethyl-substituted 1,2,4-triazole derivatives
as high-performance energetic materials
Authors: Jean'ne Shreeve, Yongxing Tang, Srinivas Dharavath,
Gregory Imler, and Damon Parrish
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To be cited as: Chem. Eur. J. 10.1002/chem.201701407
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10.1002/chem.201701407
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Nitramino- and dinitromethyl-substituted 1,2,4-triazole derivatives
as high-performance energetic materials
Yongxing Tang,[a] Srinivas Dharavath,[a] Gregory H. Imler,[b] Damon A. Parrish[b] and
Jean’ne M. Shreeve*[a]
Dedication ((optional))
Abstract: Since highly nitrated single nitrogen rich heterocycles are
important motifs in high energy density materials, extensive studies
for the development of such novel molecules have been underway.
A highly energetic moiety, 3-dinitromethyl-5-nitramino-1,2,4-triazole,
which consists of a triazole ring, and nitramino and dinitromethyl
groups, has been designed and synthesized. By pairing with
nitrogen rich cations, several ionic derivatives were obtained.
derivatives,[7] 5-nitro-3-trinitromethyl-1H-1,2,4-triazole,[5] and 3,5-
dintramino- 1,2,4-triazole[8] shown in Figure 1.
A) Previous work
NO2
NO2
NO2
NO2
NO2
NO2
NO2
O2N
O2N
N
N
N
O2N
O2N
NO2
N
N
H
HN
N
N
HN N
Theoretical
and
experimental
studies
show
that
the
O2N
O2N
NO2
H
hydroxylammonium salt (7) is highly dense, and has excellent
detonation performance with acceptable thermal stablity and
sensitivities, which are superior to those of RDX.
N
N
N
NO2
N
N
NO2
NO2
O2N
O2N
HN
N
N
N
H
N
N N
H H
B) This work
NO2
NO2
N
N
O2N
N
H
Introduction
Figure 1. Representative examples of triazoles rings with different energetic
groups
The development of high energy density materials (HEDMs)
continues to give rise to the exploration for new materials with a
detonation performance comparable to octahydro-1,3,5,7-
tetranitro-1,3,5,7-tetrazocine (HMX) and an insensitivity of 1,3,5-
triamino-2,4,6-trinitrobenzene (TATB).[1] Being environmentally
friendly is a concern that also needs to be considered. Many of
the current synthesis strategies for energetic materials have
focused on incorporating energetic groups into nitrogen rich
heterocycles.[2]
Triazole rings have emerged as a class of promising synthetic
building blocks that can be converted into a diverse range of
energetic compounds due to their high positive heats of
formation, ring strain and generation of environmentally friendly
dinitrogen upon decomposition with a concomitant high order of
energy release.[3] Many studies have been conducted on the
combination of energetic groups with triazole or bis-triazoles.[4]
With respect to insight into structure-property relationships,
highly nitrated small-ring/single heterocycles are promising
energetic materials arising from the additional energy release
upon opening of the strained ring systems during
In our continuing mission of seeking energetic compounds by
incorporating different energetic fragments into
a single
heterocyclic ring, a series of energetic salts based on a triazole
ring-containing a nitramino group and a dinitromethyl group were
designed and synthesized. All of the new compounds were fully
characterized. In addition, the potential application of the new
ionic compounds as energetic materials was experimentally and
theoretically studied.
Results and Discussion
Attempts to introduce the nitro group into ethyl 2-(5-amino-1H-
1,2,4-triazol-3-yl)acetate (1) by various nitration reagents have
been studied.[5] However, it was difficult to isolate the product
from the reaction mixture. After continuing to investigate this
reaction, we found that ethyl 2-[5-(nitramino)-1H-1,2,4-triazol-3-
yl]acetate (5) could be isolated from the nitration reaction of 1 by
using a mixture of 100% nitric acid and concentrated sulfuric
acid when the reaction time was 6 h. When the reaction time
was extended to 24 h and after decarboxylation with methanolic
ammonia, the ammonium salt 6 was isolated and characterized.
However, the yield of each step was rather poor (Scheme 1).
After isolating and confirming the structure of 5, a new
synthetic route was designed as shown. The reaction started
with diethyl malonate, which was treated with hydrazine
monohydrate in ethanol to give ethyl 3-hydrazinyl-3-
oxopropanoate (3).[9] Reaction of 3 with N-methyl-N-nitroso-N’-
nitroguanidine generated ethyl 3-[2-amino(nitroimino)methyl]-
hydrazinyl-3-oxopropanoate (4), which was treated with aqueous
sodium hydroxide and was subsequently acidified to form 5. The
decomposition.[5]
bis(dinitromethyl)-1,2,4-triazole monoanion and dianion,[6] 5-
(dinitromethyl)-3-(trinitromethyl)-1,2,4-triazole and its
Typical
examples
including
3,5-
[a]
[b]
Dr. Y. Tang, Dr. S. Dharavath, Prof. Dr. J. M. Shreeve
Department of Chemistry, University of Idaho, Moscow, Idaho,
83844-2343, USA.
Fax: (+1) 208-885-9146
E-mail: jshreeve@uidaho.edu
Dr. G. H. Imler, Dr. D. A. Parrish
Naval Research Laboratory, 4555 Overlook Avenue, Washington,
D.C. 20375, United States
Supporting information for this article is given via a link at the end of
the document.((Please delete this text if not appropriate))
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NH3/CH3OH
NO2
N
+
6
2 NH4
2 NH3OH+
or 50% NH2OH
N
O2N
N
7
NO2
NH
H2SO4
100% HNO3
H2SO4
100% HNO3
O2N
O
NO2
N
O
O
N
O
N
H
H
NH2
N
N
24 h
24 h
N
NH
N
O
NO2
NH
O
N
NO2
NH
5
1
2
1. NaOH
2. HCl
N
N
O2N
NO
NH2
H
N
·
N2H4 H2O
NH2
H
N
O
O
O
O
NO2
NH2
N
N
H
O
O
O
O
O
O
3
4
NO2
N
NO2
2 Ag+
·
AgNO3
B HCl
2 B+
NO2
6
N
O2N
N
O2N
N
N
NO2
NH
N
NH
8
H2N
HN
H
N
H
N
H
N
NH2
H2N
NH2
NH
B+
:
H2N
H2N
N
H2N
NH2
N
N
NH2 H2N
NH2
NH2
NH2
NH2
NH
NH
N
N
H2N
HN
H2N
N
NH2
9
10
11
12
13
14
Scheme 1. Synthesis of energetic salts (6–7 and 9–14) based on 3-dinitromethyl-5-nitramino-1,2,4-triazolate.
group with a calculated density of 1.744 g cm-3 at 150 K. The
nitration of 5 with mixed acid gave the intermediate 2, which was
not isolated but treated with methanolic ammonia/hydroxylamine
to give the corresponding energetic salts (6 and 7). Energetic
salts (9
̶ 14) were synthesized by metathesis reactions of
hydrochloride salts with the silver salt (8), which was prepared
by treating 6 with two equivalents of aqueous silver nitrate. All of
the new compounds were characterized by 1H, and 13C NMR,
and IR, elemental analysis and single crystal X-ray diffraction of
6 and 11.
The 15N NMR spectra for 6 and 14 are shown in Figure 2. The
signals are assigned based on comparison with compounds
reported in the literature[10] and additional theoretical calculations
B3LYP/6-311+g(2d,p) with IEF-PCM continuum solvation
models[11] of Gaussian 03 software as well as analysis of 1H-15N
heteronuclear multiple bond correlation (HMBC, Supporting
Information). For 6, the signal for the ammonium cation was
observed at the highest field of δ = -360.7 ppm. The signals for
nitrogen atoms in nitramino (N1) and dinitromethyl groups (N6)
are located at -18.8 and -23.9 ppm, respectively. Only two
signals (N4 and N5) were found for the triazole ring due to fast
proton exchange. In the spectrum of 14, the nitrogen atoms
(N12/N13/N14) in the amino groups are found at -324.9 ppm at
high field. According to the 1H-15N HMBC spectrum (Figure S19,
SI), the nitrogen atoms (N10 and N11) were found at -188.6 and
-260.9 ppm, respectively. The chemical shifts (N1, N6, N4 and
N2) in the anion of 14 are comparable to those in 6, while both
of signals (N3 and N5) in the triazole ring are seen at δ = -189.8
Figure 2. 15N NMR spectra of 6 and 14 recorded in d6-DMSO. The x axis
represents the chemical shift δ in ppm.
crystal structure is shown in Figure 3a. The hydrogen atom is
located on N6 on the triazole ring, indicating that the
deprotonation occurs at C10 and N4. The bond lengths of the
triazole ring are between the length of the corresponding single
and double bonds (C–N: 1.47 Å, 1.22 Å; N–N: 1.48 Å, 1.20 Å) [12]
N9–C5 (1.3397(16) Å) and N7–C8 (1.3270(17) Å) have a more
double bond character, while N6–C5 (1.3475(16) Å) has a more
single bond character. The nitramino group and the triazole ring
are essentially coplanar (torsion angle: <O2-N3-N4-C5 = -
1.42(19)o), while the atoms in the dinitromethyl group form
another plane. The angle between the two planes is 76.34 o. The
crystal packing of the compound is dominated by several
,
(N3) and -188.1 (N5) ppm.
Suitable crystals of 6 and 11 for single crystal X-ray diffraction
were obtained by slow evaporation of their aqueous solutions.
Compound 6 crystallizes in the orthorhombic P212121 space
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hydrogen bonds between nitrogen atoms and oxygen atoms
(Figure 3b), the details are found in the SI.
The UV−vis absorption spectra of 6 and 14 were measured in
water solution (pH = 7.02) and shown in Figure 5. The UV-vis
spectrum of 6 shows two strong absorption bands in the region
of 250–450 nm, with maximum absorptions at 288 nm and 358
nm, respectively. The molar extinction coefficients are 1.38 × 104
and 1.54 × 104 M-1 cm-1, respectively. Similarly, compound 14
also exhibits maximum absorption peaks in the same positions.
Figure 3. (a) Crystal structure of 6; thermal ellipsoids are drawn at the 50%
probability level. (b) Packing diagram of 6 viewed down the a-axis. Unit cell
indicated and dashed lines represent hydrogen bonding.
Figure 5. UV-vis absorption spectra of 6 and 14 in aqueous solution.
The physicochemical properties of energetic salts 6–7 and 9–
14 including thermal stabilities, detonation properties, heats of
formation, and impact and friction sensitivities were determined.
The results are given in Table 1. Most of new materials
decompose at < 200 oC varying in the range between 143 to 185
oC, while 14 has the highest decomposition temperature of 208
oC, which is comparable to RDX. The heats of formation were
calculated by Gaussian 03 software.[13] Compound 11 has a
negative value due to the presence of water molecules.
Compounds 6 and 9 also exhibit negative heats of formation,
while the others have positive values arising from the increased
nitrogen content. The heat of formation of 14 is 1131 kJ mol-1
(2.09 kJ g-1), which is the most positive value found for these
compounds
The trihydrate of the diaminoguanidinium salt, 11·3H2O,
crystallizes in the triclinic P-1 space group, with two formula
units per unit cell (Z = 2). Due to the presence of three water
molecules in the unit cell, it has a low calculated density of 1.625
g cm-3 at 150 K. The molecular structure is shown in Figure 4a.
The parameters in the anion are in good agreement with those
described previously for 6. In Figure 4b, the solid-state structure
is dominated by hydrogen-bonding interactions between the
anions and the diaminoguanidinium cations as well as the water
molecules.
Densities were measured by a gas pycnometer at 25 °C. The
hydroxylammonium salt 7 has a density of 1.805 g cm-3, while
the others show moderate densities varying from 1.610 to 1.752
g cm-3. By using the measured densities and calculated heats of
formation, the detonation velocities and detonation pressures
were predicted based on traditional Chapman–Jouguet
thermodynamic detonation theory using EXPLO5 6.01.[14] The
calculated detonation pressures (P) for the new salts fall in the
range of 22.6 (9) to 36.1 GPa (7), and the detonation velocities
(Dv) are distributed between 7912 (9) to 9026 m s-1 (7). The
hydroxylammonium salt 7 exhibits an excellent detonation
performance exceeding that of RDX.
Since these compounds have several nitro groups, which
have potential application as energetic compounds, their impact
and friction sensitivities were determined according to BAM
standard technology.[15] The values of the impact sensitivities of
these energetic compounds are between 10 J and 25 J.
Although the hydroxylammonium salt (7) has a friction sensitivity
of 240 N, the other compounds are more insensitive to friction
(FS: 360 N).
Figure 4. (a) Crystal structure of 11; thermal ellipsoids are drawn at the 50%
probability level. (b) Packing diagram of 11 viewed down the b-axis. Unit cell
indicated and dashed lines represent hydrogen bonding.
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Table 1. Energetic properties of the synthesized salts (6–7 and 9–14) compared to RDX.
ρ[a]
Dv [b]
P[c]
∆Hf[d]
Tdec
IS[f]
FS[g]
[e]
Comp
(g·cm-3)
(m s-1)
(GPa)
(kJ mol-1/kJ g-1)
(o C)
(J)
(N)
6
1.710
1.805
1.649
1.706
1.610
1.721
1.734
1.752
1.800
8477
9026
7912
8447
8239
8906
8459
8615
8795
28.1
36.1
22.6
26.3
24.3
29.7
27.4
28.3
34.9
-91.3/-0.34
25.0/0.08
143
15
10
20
18
15
18
20
25
7.5
360
240
360
360
360
360
360
360
120
7
168
185
159
145
165
162
208
204
9
-50.4/-0.14
171.1/0.45
-50.7/-0.11
638.9/1.40
628.7/1.46
1131/2.09
70.3/0.32
10
11
12
13
14
RDX
[a] Density measured by a gas pycnometer at 25 °C; [b] Calculated detonation velocity; [c] Calculated detonation pressure; [d] Calculated molar enthalpy of
formation in solid state; [e] Temperature of decomposition (onset); [f] Impact sensitivity; [g] Friction sensitivity.
General methods
Conclusions
All reagents were purchased from AKSci or Alfa Aesar in analytical
In conclusion, in contrast to the direct nitration of 1 followed
by decarboxylation which led to the formation of 6 at a low yield
grade and were used as received. 1H, 13C, and 15N NMR spectra were
recorded on a 300 MHz (Bruker AVANCE 300) or 500 MHz (Bruker
(12%), an improved synthetic route was designed. The
AVANCE 500) nuclear magnetic resonance spectrometer. Chemical
ammonium salt (6) is readily prepared by nitration of 5, which
was synthesized from diethyl malonate in a facile strategy.
Several nitrogen rich energetic compounds based on 3-
dinitromethyl-5-nitramino-1,2,4-triazolate were obtained by
decarboxylation or metathesis reactions. All of them were
characterized and, in addition, 6 and 11 were studied by single
crystal X-ray analysis. The energetic properties of these salts
were examined. Among them, the hydroxylammonium salt (7)
exhibits promising properties with a density of 1.805 g cm-3, a
detonation velocity of 9026 m s-1, a detonation pressure of 36.1
GPa, and acceptable sensitivities (IS: 10 J; FS: 240 N), which
suggest that it could be a promising candidate to replace the
traditional RDX.
shifts for 1H, 13C, and 15N NMR spectra are reported with respect to
external (CH3)4Si (1H and 13C) and CH3NO2 (15N). [D6]DMSO was used
as a locking solvent unless otherwise stated. Infrared (IR) spectra were
recorded on an FT-IR spectrometer (Thermo Nicolet AVATAR 370) as
thin films using KBr plates. The UV-vis spectra were measured with a
Hewlett Packard 8453 UV-Visible Spectrophotometer. The pH was
measured using a Vernier Labquest system. Density was determined at
room temperature by employing a Micromeritics AccuPyc II 1340 gas
pycnometer. Melting and decomposition (onset) points were recorded on
a differential scanning calorimeter (DSC, TA Instruments Q2000) at a
scan rate of 5 oC min-1. Elemental analyses (C, H, N) were performed on
a CE-440 Elemental Analyzer or Vario Micro cube Elementar Analyser.
Impact and friction sensitivity measurements were made using
standard BAM Fallhammer and a BAM friction tester.
a
Computational Methods
Experimental Section
The gas phase enthalpies of formation were calculated based on
isodesmic reactions (Scheme S1, SI). The enthalpy of reaction is
obtained by combining the MP2/6–311++G** energy difference for the
reactions, the scaled zero point energies (ZPE), values of thermal
correction (HT), and other thermal factors. For energetic salts, the solid-
phase enthalpy of formation is obtained using a Born−Haber energy
cycle.[16] For the compound which is a hydrate (11·2H2O), the solid-phase
enthalpy of formation is obtained by adding the gas phase heat of
formation of anhydrous compound to that of water (-241.8 kJ mol-1).[17]
Caution: The compounds described are potentially energetic materials
that might explode under certain conditions, such as impact, friction or
electric discharge. Although we have encountered no difficulties during
their preparation and handling, they must be treated carefully. Since
silver salt 8 is light sensitive, the process of making it and going through
the next step should be kept in a dark environment. Appropriate safety
precautions must be noted. Mechanical actions of these energetic
materials, involving scratching or scraping, must be avoided.
Manipulations must be carried out by using appropriate standard safety
precautions.
X-Ray crystallography data
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A clear orange needle (6) of dimensions 0.407 × 0.364 × 0.105 mm3
was mounted on a MiteGen MicroMesh using a small amount of Cargille
immersion oil. Data were collected on a Bruker three-circle platform
diffractometer equipped with a SMART APEX II CCD detector. The
crystals were irradiated using graphite monochromated MoK radiation (λ
= 0.71073 Å). An Oxford Cobra low temperature device was used to keep
the crystals at a constant 150(2) K during data collection.
Method A: Compound 1 (1.0 g, 5.9 mmol) was added slowly to a cooled
and well-stirred mixture of concerntrated sulfuric acid (10 mL) and 100%
nitric acid (4 mL) at 0 °C. The temperature was allowed to warm slowly to
room temperature over a period of 1 h, and the mixture was stirred for an
additional 24 h. The solution was poured into ice water (100 g) and
extracted with diethyl ether (20 mL × 3). The combined organic phases
were dried over magnesium sulfate and filtered. The solvent was
evaporated at ambient temperature under vacuum to give a light yellow
oil to which ethanol (10 mL) was added. The solution was stirred and
methanolic ammonia (2 M, 4 mL) was added. After 6 h, the yellow
precipitate was collected by filtration, washed with ethanol (10 mL), and
diethyl ether (10 mL) to give 6 (0.19 g, yield: 12%).
A clear yellow chunk crystal (11·3H2O) of dimensions 0.249 × 0.175 ×
0.062 mm3 was mounted on a MiteGen MicroMesh using a small amount
of Cargille immersion oil. Data were collected on a Bruker three-circle
platform diffractometer equipped with a PHOTON 100 CMOS detector.
The crystals were irradiated using a 1μs microfocus CuKa source (λ =
1.54178 Å) with Helios optics. An Oxford Cobra low temperature device
Method B: Compound 5 (1.0 g, 4.6 mmol) was added slowly to a cooled
and well-stirred mixture of concentrated sulfuric acid (10 mL) and 100%
nitric acid (4 mL) at 0 °C. The temperature was raised slowly to room
temperature over a period of 1 h, and the mixture was stirred for an
additional 24 h at this temperature. The solution was poured into ice
water (100 g) and the solution was extracted with diethyl ether (20 mL ×
3). The combined organic phases were dried over magnesium sulfate
and filtered. The solvent was evaporated at ambient temperature under
vacuum to give a light yellow oil to which was added ethanol (10 mL).
The solution was stirred and methanolic ammonia (2 M, 4 mL) was
added. After 6 h, the yellow precipitate was collected by filtration, washed
with ethanol (10 mL) and diethyl ether (10 mL) to give 6 (0.70 g, yield:
52%). Yellow solid. Td (onset): 143 oC. 1H NMR: δ 7.18 (br) ppm. 13C NMR:
δ 156.9, 152.4, 127.9 ppm. IR (KBr): ꢁꢀ = 3382(w), 1673(s), 1523(s),
1422(s), 1316(m), 1205(s), 1128(s), 1077(m), 983(m), 853(w), 824(vw),
784(w), 766(w), 753(w), 728(w), 662(w), 543(w) cm-1. Elemental analysis
for C3H10N9O6 (268.17): Calcd C 13.44, H 3.76, N 47.01 %. Found: C
13.31, H 3.64, N 47.82 %. IS: 15 J. FS: 360 N.
was used to keep the crystals at
collection.
a constant 150(2)K during data
Data collection was performed and the unit cell was initially refined
using APEX3 [v2015.5-2].[18] Data reduction was performed using SAINT
[v8.34A][19] and XPREP [v2014/2][20]
. Corrections were applied for
Lorentz, polarization, and absorption effects using SADABS [v2014/2].[21]
The structures were solved and refined with the aid of the program
SHELXL-2014/7.[22] The full-matrix least-squares refinement on F2
included atomic coordinates and anisotropic thermal parameters for all
non-H atoms. Hydrogen atoms were located from the difference
electron-density maps and added using a riding model.
Ethyl 3-[2-amino(nitroimino)methyl]-hydrazinyl-3-oxopropanoate (4)
N-methyl-N-nitroso-N’-nitroguanidine[23] (6.62 g, 45 mmol) was added in
small portions to a suspension of 1[5] (5.84 g, 40 mmol) in water (50 mL)
at room temperature. The reaction mixture was heated to 60 °C and
stirred for 24 h. The resulting precipitate was collected by filtration,
washed with cold water (80 mL), and dried in air to give 2 as a white
powder (7.05 g, yield: 76%). 1H NMR: δ 10.14 (s, 1H), 9.75 (s, 1H), 8.68
(s, 1H), 8.13 (s, 1H), 4.09 (q, 2H), 3.35 (s, 2H), 1.20 (t, 3H) ppm. 13C
NMR: δ 167.5, 165.7, 161.1, 60.9, 40.9, 14.1 ppm.
Dihydroxylammonium
3-dinitromethyl-5-nitramino-1,2,4-triazolate
(7)
Compound 5 (1.0 g, 4.6 mmol) was added slowly to a well-stirred mixture
of concentrated sulfuric acid (10 mL) and 100% nitric acid (4 mL) at 0 °C.
The temperature was raised slowly to room temperature over a period of
1 h, and the mixture was stirred for an additional 24 h. The solution was
poured into ice water (100 g) and extracted with diethyl ether (20 mL × 3).
The combined organic phases were dried over magnesium sulfate and
filtered, and the solvent was evaporated at ambient temperature under
vacuum to give a light yellow oil to which was added ethanol (10 mL).
Aqueous hydroxylamine (50% solution in water, 0.4 g) was added with
stirring. After 6 h, a yellow precipitate was collected by filtration, washed
with ethanol (10 mL) and diethyl ether (10 mL) to give 7 (0.63 g, yield:
45%). Yellow solid. Td (onset): 168 oC. 1H NMR: δ 8.76 (br) ppm. 13C NMR:
δ 155.8, 150.3, 126.6 ppm. IR (KBr): ꢁꢀ = 1684(w), 1518(s), 1470(m),
1399(m), 1239(s), 1135(w), 1090(w), 987(w), 828(vw), 746(w), 660(vw),
540(w) cm-1. Elemental analysis for C3H10N9O8 (300.17): Calcd C 12.00,
H 3.36, N 42.00 %. Found: C 12.04, H 3.03, N 40.75 %. IS: 10 J. FS: 240
N.
Ethyl 2-(5-(nitramino)-1H-1,2,4-triazol-3-yl)acetate (5)
Method A: Compound 1 (1.0 g, 5.9 mmol) was added to a mixture of
100% nitric acid (4 mL) and concentrated sulfuric acid (10 mL) at 0 oC.
After stirring for 30 minutes at this temperature, the reaction mixture was
allowed to warm to room temperature and continue with stirring for 6 h.
The reaction mixture was poured into 100 g ice-water, the precipitate was
collected by filtration, washed with cold water (30 mL) and dried in air to
give 5 (0.38 g, yield: 30%).
Method B: A solution of sodium hydroxide (0.8 g, 20 mmol) in water (10
mL) was added to a suspension of 4 (4.66 g, 20 mmol) in water (50 mL).
The reaction mixture was heated at reflux for 2 h and cooled to room
temperature and acidified with concentrated hydrochloric acid to pH ~ 1.
The resulting precipitate was collected and washed with water and dried
in air to give 5 (3.00 g, yield: 70%).
General procedure for preparing 9 ̶ 14. The ammonium salt 6 (0.54 g,
2.0 mmol) was dissolved in water (30 mL); then silver nitrate (0.75 g, 4.4
mmol) was added. The reaction mixture was stirred for 2 h at room
temperature. Silver salt 8 was obtained by filtration and washed with
water (30 mL). Then 8 was suspended in water (40 mL), and two
White solid. Td (onset): 183 oC. 1H NMR: δ 14.05 (br), 4.13 (q, 2H), 3.89 (s,
2H), 1.20 (t, 3H) ppm. 13C NMR: δ 167.5, 152.8, 145.1, 61.2, 31.7, 13.9
ppm. IR (KBr): νꢀ = 3294(m), 1723(s), 1616(s), 1572(s), 1508(m), 1446(w),
1403(w), 1382(w), 1322(m), 1259(w), 1224(m), 1089(w), 1022(w),
1011(w), 995(w), 875(w), 779(w), 721(w), 699(w) cm-1. Elemental
analysis for C6H9N5O4 (215.17): Calcd C 33.49, H 4.22, N 32.55 %.
Found: C 32.95, H 4.02, N 32.63 %.
equivalents of
a corresponding hydrochloride salt was added. The
temperature of the reaction mixture was increased to 60 oC and it was
stirred for 4 h. After removing the insoluble solids, the filtrate was
concentrated to give the final products (9 ̶ 14).
Diammonium 3-dinitromethyl-5-nitramino-1,2,4-triazolate (6)
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10.1002/chem.201701407
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Diguanidinium 3-dinitromethyl-5-nitramino-1,2,4-triazolate (9) Yellow
solid. Td (onset): 185 oC. 1H NMR: δ 12.93 (br), 7.03 (6H) ppm. 13C NMR: δ
158.0, 156.4, 152.7, 127.8 ppm. IR (KBr): ꢁꢀ = 3450(w), 3174(w), 1665(s),
1581(vw), 1544(m), 1515(w), 1459(m), 1403(w), 1388(w), 1341(m),
1262(m), 1211(w), 1147(w), 1060(vw), 1045(w), 983(w), 737(w), 619(vw)
cm-1. Elemental analysis for C5H13N13O6 (351.24): Calcd C 17.10, H 3.73,
N 51.84 %. Found: C 17.25, H 3.59, N 51.71 %. IS: 20 J. FS: 360 N.
500 MHz NMR spectrometer is gratefully acknowledged. We are
also indebted to and thank Dr. O. Charles Nwamba for
determing UV-vis spectra.
Keywords: Triazole • nitramino group • dinitromethyl group •
energetic materials • nitration
Diaminoguanidinium
3-dinitromethyl-5-nitramino-1,2,4-triazolate
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a) D. G. Piercey, D. E. Chavez, B. L. Scott, G. H. Imler, D. A. Parrish,
Angew. Chem. Int. Ed. 2016, 55, 15315–15318; Angew. Chem. 2016,
128, 15541–15544. b) T. M. Klapötke, Chemistry of High-Energy
Materials, 2nd ed. Walter de Gruyter, Berlin, 2012.
(10) Yellow solid. Td (onset): 159 oC. 1H NMR: δ 12.86 (br), 8.67 (1H), 7.27
(2H), 6.87 (2H), 4.66 (2H) ppm. 13C NMR: δ 158.8, 156.6, 152.8, 127.9
ppm. IR (KBr): ꢁꢀ = 3422(w), 3325(w), 1673(s), 1518(s), 1486(w), 1443(w),
1368(m), 1328(m), 1247(w), 1168(m), 1124(m), 1082(m), 1014(w),
978(m), 868(vw), 821(w), 768(vw), 751(vw), 616(vw) cm-1. Elemental
analysis for C5H15N15O6 (381.27): Calcd C 15.75, H 3.97, N 55.11 %.
Found: C 15.87, H 3.76, N 54.34 %. IS: 18 J. FS: 360 N.
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a) X. Zhao, S. Li, Y. Wang, Y. Li, F. Zhao, S. Pang, J. Mater. Chem. A
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Di(diaminoguanidinium) 3-dinitromethyl-5-nitramino-1,2,4-triazolate
dihydrate (11) Yellow solid. Td (onset): 145 oC. 1H NMR: δ 8.83 (2H), 7.27
(2H), 4.64 (4H) ppm. 13C NMR: δ 159.7, 156.5, 153.4, 127.6 ppm. IR
(KBr): ꢁꢀ = 3406(w), 3265(w), 3141(vw), 1686(s), 1511(s), 1464(m),
1431(w), 1393(w), 1313w, 1221(m), 1172(w), 1119(m), 982(m), 860(vw),
819(w), 753(vw), 636(w), 596(w) cm-1. Elemental analysis for C5H22N17O8
(448.34): Calcd C 13.39, H 4.95, N 53.11 %. Found: C 13.73, H 4.98, N
52.65 %. IS: 15 J. FS: 360 N.
[4]
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14485–14492. b) H. Xue, H. Gao, B. Twamley, J. M. Shreeve, Chem.
Mater. 2007, 19, 1731–1739. c) Y. Tang, H. Gao, D. A. Parrish, J. M.
Shreeve, Chem. Eur. J. 2015, 21, 11401–11407. d) A. A. Dippold, D.
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Di(triaminoguanidinium) 3-dinitromethyl-5-nitramino-1,2,4-triazolate
(12) Yellow solid. Td (onset): 165 oC. 1H NMR: δ 8.58 (3H), 4.49 (6H) ppm.
13C NMR: δ 159.0, 157.0, 153.0, 128.2 ppm. IR (KBr): ꢁꢀ = 3231(w),
1587(s), 1508(m), 1494(m), 1421(m), 1364(w), 1288(w), 1242(m),
1150(m), 1097(w), 1023(w), 978(w), 947(w), 826(w), 787(w), 760(w),
749(w), 725(vw) cm-1. Elemental analysis for C5H20N19O6 (442.34): Calcd
C 13.58, H 4.56, N 60.16 %. Found: C 13.48, H 4.26, N 60.66 %. IS: 18 J.
FS: 360 N.
a) V. Thottempudi, H. Gao, J. M. Shreeve, J. Am. Chem. Soc. 2011,
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Di(3,4-diamino-1,2,4-triazolium)
3-dinitromethyl-5-nitramino-1,2,4-
triazolate (13) Yellow solid. Td (onset): 162 oC. 1H NMR: δ 8.39 (1H), 8.00
(2H), 6.02 (2H) ppm. 13C NMR: δ 152.7, 151.0, 143.5, 141.8, 122.6 ppm.
IR (KBr): ꢁꢀ = 3420(w), 3341(w), 3285(vw), 1698(s), 1591(s), 1543(m),
1517(w), 1473(w), 1439(m), 1394(w), 1351(w), 1310(w), 1268(m),
1221(s), 1151(s), 1078(w), 989(vw), 966(w), 955(w), 868(w), 773(w),
746(w), 717(w) cm-1. Elemental analysis for C7H13N17O6 (431.29): Calcd
C 19.49, H 3.04, N 55.21 %. Found: C 19.52, H 3.07, N 55.25 %. IS: 20 J.
FS: 360 N.
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Di{3,6,7-triamino-7H-[1,2,4]triazolo[5,1-c][1,2,4]triazol-2-ium}
dinitromethyl-5-nitramino-1,2,4-triazolate (14) Yellow solid. Td
3-
:
(onset)
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208 oC. 1H NMR: δ 7.34 (2H), 7.02 (2H), 5.80 (2H) ppm. 13C NMR: δ
159.6, 154.0, 147.9, 146.4, 141.9, 124.2 ppm. IR (KBr): ꢁꢀ = 3430(w),
1666(s), 1639(s), 1572(m), 1528(w), 1429(s), 1398(m), 1304(w), 1198(m),
1129(m), 1109(m), 1068(w), 1003(vw), 981(w), 920(w), 883(vw), 842(vw),
828(w), 748(m), 727(w), 707(w), 620(w) cm-1. Elemental analysis for
C9H16N23O6 (542.37): Calcd C 19.93, H 2.97, N 59.40 %. Found: C 19.89,
H 2.84, N 59.49 %. IS: 25 J. FS: 360 N.
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Acknowledgements ((optional))
Financial support of the Office of Naval Research (N00014-16-1-
2089), the Defense Threat Reduction Energy (HDTRA 1-15-1-
0028), and the M. J. Murdock Charitable Trust (No.
201420:MNL:11/20/2014) for funds supporting the purchase of a
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Several energetic salts based on a
highly nitrated triazole ring, 3-
dinitromethyl-5-nitramino-1,2,4-
triazole, were prepared. The
hydroxylammonium salt shows
promising energetic properties.
Y. Tang, S. Dharavath, G. H. Imler, D. A.
Parrish, J. M. Shreeve*
Page No. – Page No.
Nitramino- and dinitromethyl-
substituted 1,2,4-triazole derivatives
as high- performance energetic
materials
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