Synthesis, characterization, and thermal analysis of two energetic Ionic Salts based on 3,4-Diamino-1,2,4-triazole (DATr)

Article abstract of DOI:10.1002/zaac.201300247

Two energetic ionic salts DATr·NTO (2) and DATr·TNR (3) of 3,4-diamino-1,2,4-triazole (DATr) (1) were synthesized by reaction of 3,4-diamino-1,2,4-triazole with either 3-nitro-1,2,4-triazole-5-one (NTO) or 2,4,6-trinitro-resorcinol (TNR) in aqueous soluti

Full text of DOI:10.1002/zaac.201300247

ARTICLE
DOI: 10.1002/zaac.201300247
Synthesis, Characterization, and Thermal Analysis of Two Energetic Ionic
Salts Based on 3,4-Diamino-1,2,4-triazole (DATr)
Jin-Ting Wu,[a] Jian-Guo Zhang,*[a] Xin Yin,[a] Mou Sun,[a] and Tong-Lai Zhang[a]
Keywords: 3,4-Diamino-1,2,4-triazole; 3-Nitro-1,2,4-triazole-5-one; 2,4,6-Trinitro-resorcinol; Crystal structure; Thermal analy-
sis; Energetic compounds; Sensitivity test
Abstract. Two energetic ionic salts DATr·NTO (2) and DATr·TNR (3) tal system, space group P21/c. The crystal density is 1.693 g·cm–3 and
of 3,4-diamino-1,2,4-triazole (DATr) (1) were synthesized by reaction 1.738 g·cm–3, respectively. The thermal decomposition characteristics
of 3,4-diamino-1,2,4-triazole with either 3-nitro-1,2,4-triazole-5-one
of the title compounds were investigated using differential scanning
(NTO) or 2,4,6-trinitro-resorcinol (TNR) in aqueous solution. Their calorimetry (DSC) and thermogravimetry/differential thermogravime-
structures were characterized by FT IR spectroscopy (FT-IR) and X- try (TG/DTG) technologies. Furthermore, the sensitivity properties
ray single-crystal diffraction analysis. Their molecular structure and were determined by standard methods.
crystal structure were determined. They belong to the monoclinic crys-
band of 3348 cm–1 is predicted for the OH group, and the
Introduction
bands of 1616 cm–1, 1565 cm–1, 1494 cm–1, and 1447 cm–1 are
Energetic salts as a unique class of high energetic materials
assigned to the stretching vibration of the benzene cycle of
due to the lower vapor pressures and higher densities than their
atomically similar non-ionic analogues have been widely in-
compound 3. C–N stretching vibrations at 1020–1360 cm–1 are
visible in both spectra of 2 and 3. In addition, the bands of
vestigated.[1–3] Some of them have attractive energetic proper-
lower intensity correspond to vibrational modes in the cation
ties such as good thermal stability and high density.[4–6] The
and the two compounds show bands in the range of 3400–
design of energetic materials based on combinations of dif-
3330 and 1295–1145 cm–1, which are due to the symmetric
ferent ions for a specific purpose provides a powerful method-
stretching of the NH2 groups and the rocking/twisting vi-
ology.[7,8] Triazole is a high nitrogen-containing heterocycle,
brational modes of the NH2 groups, respectively.[11]
which leads to high energetic performances arising from an
additional energy release upon opening of the strained ring
systems during decomposition.[9,10]
Molecular Structure
In this paper, two energetic ionic salts DATr·NTO (2) and
DATr·TNR (3) based on 3,4-diamino-1,2,4-triazole (DATr) (1)
were synthesized by reacting 3,4-diamino-1,2,4-triazole with
either 3-nitro-1,2,4-triazole-5-one (NTO) or 2,4,6-trinitro-res-
orcinol (TNR) in aqueous solution. Their crystal structures
were determined by X-ray single-crystal diffraction analysis
and their thermal decomposition characteristics has been inves-
tigated using DSC and TG-DTG technologies.
There are one 3-nitro-1,2,4-triazole-5-one anion or 2,4,6-tri-
nitro-resresorcinol anion and one 3,4-diamino-1,2,4-trizolium
in 2 and 3, respectively, which are connected by electrostatic
attraction. The molecular structures of compounds 2 and 3 are
shown in Figure 2. One proton from one NTO molecule trans-
fers to a molecule of 1 (N2 accepts the proton). There exist
two planes in the molecular structure of compound 2, as shown
in Figure 2a. The first one is the NTO anion plane (A): 0.087x
+ 0.468y – 0.879z = –0.0827, and the second one is the struc-
ture plane (B) from 1: 0.196x – 0.007y – 0.980z = –4.164. The
angle between A and B is 28.86°. The C1–O1 bond length is
1.27 Å, which is 0.06 Å longer than the normal C=O bond
length (1.21 Å) and 0.18 Å shorter than the normal C–O bond
length (1.45 Å), which indicates that the carbonyl bonds have
a certain degree of distortion due to the loss of the hydrogen
atom on the adjacent N3 atom. This is mainly due to the π
bond of the triazole ring; the electronegativity is enhanced
such that the oxygen atom of the carbonyl bond is excluded
while the intensity of the carbonyl group is reduced.
Results and Discussion
IR Spectroscopy
The FT-IR spectra of 2 and 3 are shown in Figure 1. In
Figure 1a, the band at 1697 cm–1 is assigned to the C=O group
stretching vibration for NTO of compound 2. In Figure 1b, the
* Prof. Dr. J.-G. Zhang
Fax: +86-10-68918038
E-Mail: zjgbit@bit.edu.cn
[a] State Key Laboratory of Explosion Science and Technology
Beijing Institute of Technology
Beijing 100081, P. R. China
In the molecular structure of compound 3, a proton from
one hydroxyl group of the TNR molecule transfers to 1 and
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Energetic Ionic Salts Based on 3,4-Diamino-1,2,4-triazole (DATr)
Figure 1. FT-IR spectra of (a) DATr·NTO (2) and (b) DATr·TNR (3).
Figure 2. Molecular structure of (a) DATr·NTO (2) and (b) DATr·TNR (3).
two nitrogen atoms accept protons. There exist three planes in
the molecular structure of 3: the benzene ring plane (C):
0.8226x + 0.5486y – 0.1498z = 1.8984, another plane is the
3,4-diamino-1,2,4–triazolium unit (D): 0.8328x – 0.0607y –
0.4402z = –2.2520. The angle between C and D is 42.76°. The
benzene ring structure remains of its original nature, where six
carbon atoms are still coplanar, but the interior angles of benz-
ene ring have already changed due to the external groups. The
angle of C5–C6–C7 has the least impact (120.46°), whereas
the angles of C7–C8–C3 (126.44°) and C8–C3–C4 (112.72°)
have the large change.
The packing diagram of 2 shows that the intermolecular ar-
rangement of 3,4-diamino-1,2,4-triazolium consists of regular
stacking, the intermolecular arrangement of 3-nitro-1,2,4-tri-
azole-5-one anion consists of mutual intersecting and stagger-
ing; while the packing diagram of 3 indicates a similar arrange-
ment (see Figure 3). The kind of arrangement improves the
degree of disorder of the entire unit cell, increasing the entropy
of the molecule as a whole, so the stability of the molecule
increased.
For compound 2, the DSC curve shows a sharp exothermic
process starting at 231.1 °C with a peak temperature of
236.7 °C. Corresponding to the exothermic decomposition, a
sharp mass loss (58.4%) was found in the TG-DTG curves,
afterwards there is a further slow process of thermal decompo-
sition with continuous mass loss and a great amount of heat
and gases were released in the total decomposition process and
left nothing.
For compound 3, the DSC curve shows that there are two
processes: one endothermic process occurs at 201.4 °C and one
exothermic process with a top at 261.9 °C. At the same time,
the TG-DTG curves indicate two stages in the process
of thermal decomposition. The first mass loss stage occurs at
272.0 °C, the first stage of mass loss of 59.2% of the
initial mass for 3. The second stage is a slow process of ther-
mal decomposition with continuous mass loss, and left
nothing.
The constant-volume combustion heats (Qv) of DATr·NTO
(2) and DATr·TNR (3) were –10.3417 MJ·kg–1 and
–10.5384 MJ·kg–1, respectively, which were measured with a
Parr company 1104 oxygen bomb calorimeter in an oxygen
atmosphere. The data indicate that both of them release large
amounts of energy upon decomposing. The combustion equa-
tion of the compounds is as follows:
Thermal Decomposition
The DSC and TG-DTG curves of compounds 2 and 3 with
a linear heating rate of 10 K·min–1 are shown in Figure 4 and
Figure 5, respectively.
Z. Anorg. Allg. Chem. 2013, 2354–2358
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J.-T. Wu, J.-G. Zhang, X. Yin, M. Sun, T.-L. Zhang
ARTICLE
Figure 3. Views of stacking unit cell for packing for (a) DATr·NTO (2) and (b) DATr·TNR (3).
Figure 4. DSC curves of (a) DATr·NTO (2) and (b) DATr·TNR (3) at a heating rate of 10 K·min–1.
Figure 5. TG-DTG curves of (a) DATr·NTO (2) and (b) DATr·TNR (3) at a heating rate of 10 K·min–1.
CaHbOcNd + (a + 0.25b – 0.5c)O2 Ǟ aCO2 + 0.5bH2O +0.5dN2 (1) ΔfHo298(R) = ΔfHo (P) – ΔrH
(3)
298
The energy of combustion is calculated by the formula:
ΔH = Qp = QV + ΔnRT
With the known enthalpies of the formation of carbon
dioxide [ΔfHo298(CO2, g) = –393.5 kJ·mol–1] and water
[ΔfHo298(H2O, l) = –285.8 kJ·mol–1], the enthalpy of the for-
mation of 2 and 3 can be calculated with –214.6 kJ·mol–1 and
–678.5 kJ·mol–1, respectively.
(2)
The enthalpies of the compounds can be calculated from the
energy of combustion on the basis of Equation (1) and the
Hess’s law as applied in thermochemical Equation (3).
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Z. Anorg. Allg. Chem. 2013, 2354–2358

Energetic Ionic Salts Based on 3,4-Diamino-1,2,4-triazole (DATr)
Physicochemical Properties
sensitivity analysis, both of the two ionic salts have potential
application as energetic materials and gas generating-agent
components used in military and civilian fields.
The detonation parameters were calculated by equations
proposed by Keshavarz.[12] Table 1 shows that for compounds
2 and 3 the calculated detonation pressures (P) are 17.1 and
19.5 GPa, which are comparable to that of TNT (19.5 GPa).[13]
The detonation velocities (D) are 6320 m·s–1 (2) and 6699 m·s–
Experimental Section
1
(3) comparable to TNT (6881 m·s–1) and RDX (8977 m·s–
Synthesis: 3,4-Diamino-1,2,4-triazolium chloride was synthesized ac-
cording to a literature method[16] starting from the reaction of the di-
aminoguanidinium chloride with formic acid, and hydrochloric acid as
catalytic agent under reflux conditions. Equal potassium hydroxide
was used to neutralize and to get 3,4-diamino-1,2,4-triazole (1).
Scheme 1 shows the synthesis route of the two energetic ionic salts.
1).[13,14]
Table 1. Physicochemical Properties of DATr·NTO (2) and DATr·TNR
(3).
DATr·NTO (2)
DATr·TNR (3)
a)
Tm
Td
OB
N
P
D
–
203.6
261.9
–55.8
32.5
19.5
6699
b)
c)
236.7
–59.4
55.0
17.1
6320
d)
e)
f)
a) Melting point/DSC endothermic peak. b) Thermal degradation/DSC
main exothermic peak. c) Oxygen balance. d) Nitrogen content /%. e)
Detonation pressure /GPa. f) Detonation velocity /m·s–1.
Sensitivity Tests
On the basis of the Chinese standard,[15] the impact and fric-
tion sensitivities as well as the flame sensitivity were deter-
mined. The results of the sensitivity tests of DATr·NTO (2)
and DATr·TNR (3) are listed in Table 2.
Scheme 1. Syntheses of 3,4-diamino-1,2,4-triazole and its salts 2 and
3.
Table 2. Results of sensitivity tests on DATr·NTO (2) and DATr·TNR
(3).
Table 3. Crystal data and structure refinement parameters for 2 and 3.
DATr·NTO (2)
DATr·TNR (3)
DATr·NTO (2)
DATr·TNR (3)
Friction sensitivity /%
Impact sensitivity /cm
Flame sensitivity, h50 /cm
70
40.5
18.43
50
35.2
13.2
Empirical formula
Formula mass
C4H7N9O3
229.19
C8H8N8O8
344.22
Temperature /K
153(2)
153(2)
Crystal system
Space group
Z
a /Å
monoclinic
P21/c
4
10.323(6)
6.186(4)
14.080(8)
91.047(6)
899.0(9)
1.693
monoclinic
P2(1)
2
10.087(3)
6.019(2)
11.036(4)
100.974(4)
657.7(4)
1.738
The sensitivity measurement results for DATr·NTO showed
that the 50% firing height (h50) for flame sensitivity was
18.43 cm and the friction sensitivity firing rate was 70% with
a 1 kg hammer, 90° angle, and 1.96 MPa pressure. The impact
sensitivities of the compounds were determined with a fall-
hammer apparatus. The compound was compressed between
two steel poles and hit with a 0.8 kg hammer. The test results
showed that the 50% firing height is 40.5 cm (3.18 J) for 2,
and 35.2 cm (2.76 J) for 3, comparable to TNT (15 J) and RDX
(7.5 J).[13,14]
b /Å
c /Å
β /°
Cell volume /Å3
Density, calculated /g·cm–3
Absorption coefficient /mm–1 0.71073
0.71073
352
F(000) /Å
472
Θ Range for data collection /° 2.468–31.502
h, k, and l range
2.51–31.50
–14 Ͻ h Ͻ 12
–8 Ͻ k Ͻ 8
–16 Ͻ l Ͻ 16
8154
–15 Ͻ h Ͻ 14
–9 Ͻ k Ͻ 8
–20 Ͻ l Ͻ 20
8406
2949 [Rint = 0.0333] 4167 [Rint = 0.0223]
1.001
In other words, both of the ionic salts are sensitive and can
be regarded as potential energetic materials.
Reflection measured
Independent reflection (Rint
Refinement method
)
0.999
Conclusions
Final R1 and wR2 [I Ͼ 2σ(I)] R1 = 0.0460
R1 = 0.0351
wR2 = 0.0757 b)
R1 = 0.0386
wR2 = 0.0776 b)
0.244, –0.174
wR2 = 0.1079 a)
Two energetic ionic salts based on 3,4-diamino-triazole were
prepared and characterized by FT-IR spectroscopy and X-ray
single-crystal diffraction analysis. Thermal analysis illustrated
that a rapid exothermic process occurs in very short time and
a great number of gases was produced, and left finally nothing
R1 and wR2 indices (all data)
R1 = 0.0606
wR2 = 0.1175 a)
0.259, –0.235
Largest diff. peak and hole
/e·Å–3
a) w = 1/[σ2(Fo )+(0.0748P)2 + 0.1090P], where P = (Fo +2Fc )/3. b) w =
2
2
2
of the two energetic ionic salts. According to the thermal and 1/[σ2(Fo )+(0.0373P)2 + 0.0000P], where P = (Fo +2Fc )/3.
2
2
2
Z. Anorg. Allg. Chem. 2013, 2354–2358
© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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J.-T. Wu, J.-G. Zhang, X. Yin, M. Sun, T.-L. Zhang
ARTICLE
DATr·NTO (2) and DATr·TNR (3) were prepared by reacting 3,4-di-
amino-1,2,4-triazole (1) with an aqueous solution of 3-nitro-1,2,4-tri-
azole-5-one (NTO) or 2,4,6-trinitro-resresorcinol (TNR), respectively.
The mixtures were kept stirring over 15 min at 50 °C. The two title
salts were obtained by slow spontaneous crystallization, filtered off,
and washed three times with methanol.
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Received: May 16, 2013
Published Online: July 23, 2013
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Z. Anorg. Allg. Chem. 2013, 2354–2358