Novel catenated N6 energetic compounds based on substituted 1,2,4-triazoles: Synthesis, structures and properties

Article abstract of DOI:10.1039/c8ra02491j

1-Amino-3,5-dinitro-1,2,4-triazole (ADNT) was prepared using an efficient N-amination process. Three novel catenated N₆ energetic derivatives of ADNT, which contain 1,1′-azobis(3,5-dinitro-1,2,4-triazole) (ABDNT), 1,1′-azobis(3-chloro-5-nitro-1,2,4-triazole) (ABCNT) and 1,1′-azobis(3,5-diazido-1,2,4-triazole) (ABDAT), were synthesized from N-amino oxidative-coupling reactions of ADNT. All compounds were fully characterized by ¹H and ¹³C nuclear magnetic resonance spectroscopies, infrared spectroscopy, elemental analysis, mass spectrum, as well as differential scanning calorimetry (DSC). The crystal structure of compound ABCNT was confirmed by single-crystal X-ray diffraction showing an extensive conjugated structure. The densities of energetic derivatives ranged from 1.71 to 1.93 g cm^-3, and all compounds have positive heats of formation in the range of 774.8 to 2150.8 kJ mol^-1. Based on the measured densities and calculated heats of formation, theoretical performance calculations, including detonation pressures (29.6-42.4 GPa) and detonation velocities (8.22-9.49 km s^-1) were carried out using the Gaussian 09 program and Kamlet-Jacobs equations, and they compared favorably with those of TNT and RDX. These properties make them potentially competitive as new high energy-density compounds.

Full text of DOI:10.1039/c8ra02491j

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Novel catenated N6 energetic compounds based on
substituted 1,2,4-triazoles: synthesis, structures
and properties†
Cite this: RSC Adv., 2018, 8, 13755
*
*
Bin Wang, Pei Chang, Jianjian Hu, Tao Chen, Yinglei Wang
Yanan Li,
and Bozhou Wang
1-Amino-3,5-dinitro-1,2,4-triazole (ADNT) was prepared using an efficient N-amination process. Three
novel catenated N6 energetic derivatives of ADNT, which contain 1,10-azobis(3,5-dinitro-1,2,4-triazole)
(ABDNT), 1,10-azobis(3-chloro-5-nitro-1,2,4-triazole) (ABCNT) and 1,10-azobis(3,5-diazido-1,2,4-triazole)
(ABDAT), were synthesized from N-amino oxidative-coupling reactions of ADNT. All compounds were
fully characterized by 1H and 13C nuclear magnetic resonance spectroscopies, infrared spectroscopy,
elemental analysis, mass spectrum, as well as differential scanning calorimetry (DSC). The crystal
structure of compound ABCNT was confirmed by single-crystal X-ray diffraction showing an extensive
conjugated structure. The densities of energetic derivatives ranged from 1.71 to 1.93 g cmꢀ3, and all
compounds have positive heats of formation in the range of 774.8 to 2150.8 kJ molꢀ1. Based on the
measured densities and calculated heats of formation, theoretical performance calculations, including
detonation pressures (29.6–42.4 GPa) and detonation velocities (8.22–9.49 km sꢀ1) were carried out
using the Gaussian 09 program and Kamlet–Jacobs equations, and they compared favorably with those
of TNT and RDX. These properties make them potentially competitive as new high energy-density
compounds.
Received 21st March 2018
Accepted 5th April 2018
DOI: 10.1039/c8ra02491j
rsc.li/rsc-advances
are at the forefront of high energy research.4 Recently, the
combination of an azo group with nitrogen-rich heteroaromatic
Introduction
rings has been extensively studied because the azo linkage not
only desensitizes but also dramatically increases the heats of
formation of high-nitrogen compounds such as 3,30-
azobis(1,2,4-triazole) (1), 5,50-dinitro-3,30-azo-1H-1,2,4-triazole
Traditional energetic materials including quintessential explo-
sives such as TNT (2,4,6-trinitrotoluene), RDX (1,3,5-trinitro-
1,3,5-triazinane)
and
HMX
(1,3,5,7-tetranitro-1,3,5,7-
tetrazocane) are based on the oldest strategy in the design of
energetic materials: the presence of fuel and oxidizer in the
same molecule. New strategies in energetic materials' research
focus on nitrogen-rich/high positive heat of formation
compounds.1 Nitrogen-rich compounds have therefore received
increasing attention as promising candidates for high energy-
density materials (HEDM) which might be used as propel-
lants, explosives or especially as gas generators,2 and the
generation of nitrogen gas as a nal product of nitrogen-rich
compounds is highly favored for the enhancement of energy
and avoiding environmental pollution.3 Nitrogen-rich
compounds based on C/N heteroaromatic rings with high
nitrogen content like triazole, tetrazole, triazine and tetrazine
(2),
3,30-azobis-(6-amino-1,2,4,5-tetrazine)
(3),
4,40,6,60-
tetra(azido)azo-1,3,5-triazine (4) and are four representative
compounds of this kind (Scheme 1),5 where the two hetero-
aromatic rings are connected by a C–N]N–C linkage. However,
if the azo group is attached to the nitrogen of the hetero-
aromatic rings to create a rather long chain of catenated
nitrogens (N–N]N–N linkage), such a polynitrogen structure
State Key Laboratory of Fluorine & Nitrogen Chemicals, Xi'an Modern Chemistry
Research Institute, Xi'an, Shanxi 710065, P. R. China. E-mail: lyn2003080094@126.
com; wangyl204@163.com
† Electronic supplementary information (ESI) available: (1) X-ray crystallography,
(2) 1H and 13C NMR spectra of all compounds, (3) the details for the heat of
formation. CCDC 1826501. For ESI and crystallographic data in CIF or other
electronic format see DOI: 10.1039/c8ra02491j
Scheme 1 Examples of reported high-nitrogen compounds with
C,C0-azo linkage.
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could result in unique properties and features of these energetic azobis(3,5-diazido-1,2,4-triazole) (ABDAT) (Scheme 4). All the
compounds.
compounds were characterized by 1H and 13C nuclear magnetic
In the pursuit of novel nitrogen-rich energetic materials, resonance spectroscopies, infrared spectroscopy, elemental
some catenated nitrogen-atom compounds containing the N– analysis, mass spectrum and differential scanning calorimetry
N]N–N linkage have been synthesized over the past years, such (DSC). The single crystal of ABCNT was determined by X-ray
as 4,40-azo-1,2,4-triazole (5),5a,6 1,10-azobis-1,2,3-triazole (6), 1,10- diffraction. Computational calculations conrming the high
azobis(tetrazole) (7), 2,20-azobis(5-nitrotetrazole) (8) and 1,10- energetic performance of all derivatives were also performed.
azobis(5-methyltetrazole) (9) (Scheme 2).7 Unfortunately, most
of the above compounds don't own excellent detonation
performance (such as compounds 5, 6, 9) or thermal unstable
Results and discussion
Synthesis of N-amination agents
(such as compounds 7, 8, 9).
The N-amination of electron-rich systems, such as imidaz-
oles, pyrazoles, triazoles and tetrazoles, have been reported for
several researchers,7c,8 using the commercially available
hydroxylamine-O-sulfonic acid (HOSA) as N-amination agent.
However, HOSA aminations unfortunately do not apply to
electron-poor systems. The addition of an amino group to
energetic compounds could improve the stability, for example
amino–nitro compounds such as diaminodinitroethylene (FOX-
7) or 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) are
low-sensitivity and high-performance explosives that are the
standard for insensitive explosives.7c,9 N-Amino compounds
have the further advantage that their heats of formation and
other explosive performance increase as a result of the addi-
tional N–N bond. Furthermore, new potential nitrogen ligands
for high energy-density materials can be designed and synthe-
sized by the N–NH2 group of N-amino compounds.
O-Tosylhydroxylamine (THA)10 is a powerful amination agent
well known to aminate electron-poor systems, but THA is
unfortunately not stable in storage under room temperature
condition, so before each reaction it was rstly prepared. In this
paper, several new N-amination agents were synthesized
(Scheme 3), and the thermal stability were investigated by DSC
method. Among of them, 2,4,6-trimethylbenzenesulfonyl
The commercially hydroxylamine-O-sulfonic acid (HOSA) as N-
amination agent could only be used to the N-amination reac-
tion of electron-rich systems, and the yields of N-amination
products were always lower. O-Tosylhydroxylamine (THA) is an
efficient N-amination agent that could aminate electron-poor
systems and have better yields of targets, but THA is not
stable in storage under room temperature condition.7c,8,10 In our
studies, seven new N-amination agents, such as 2-nitro-
benzenesulfonyl
benzenesulfonyl
hydroxylamine
hydroxylamine
(2-NSH),
(3-NSH),
3-nitro-
2,4-
dinitrobenzenesulfonyl hydroxylamine (DNSH), 2,4-dime-
thylbenzenesulfonyl hydroxylamine (DMSH), 2,4,6-trime-
thylbenzenesulfonyl
hydroxylamine
(MSH),
2,4,6-
triisopropylbenzenesulfonyl hydroxylamine (TSH) and 2,4,6-
trinitrophenyl hydroxylamine (PHA), were synthesized using O-
substituted benzenesulfonyl chloride and ethyl acetohydrox-
amate as starting materials by the reactions of condensation
and hydrolysis. The compounds 2-NSH, 3-NSH, DNSH, and
DMSH easily decomposed in the solid state at room tempera-
ture more than half an hour, but they was stable in the solution
at lower temperature for several weeks. According to the results
of DSC experiments, the compounds MSH, TSH, and PHA could
be stable in storage under ambient condition. The thermal
decomposition temperatures were 79.3 ꢁC, 107.7 ꢁC, and
hydroxylamine
(MSH),
2,4,6-triisopropylbenzenesulfonyl
hydroxylamine (TSH) and 2,4,6-trinitrophenyl hydroxylamine
(PHA) are stable in storage under room temperature. We have
used MSH to aminate the electron-poor 3,5-dinitro-1,2,4-
triazolate anion yielding 1-amino-3,5-dinitro-1,2,4-triazole
ꢁ
94.1 C, respectively.
Synthesis of ADNT and its energetic derivatives
(ADNT). Three energetic derivatives of ADNT have also been Various N,N0-diazo-bridged compounds of single-ring azole-
prepared: the azo coupling product of ADNT, 1,10-azobis(3,5- based compounds, such as substituted pyrazole, imidazole,
dinitro-1,2,4-triazole) (ABDNT); the azo coupling and chlorina- 1,2,3-triazole and tetrazole, have been synthesized by several
tion product of ADNT, 1,10-azobis(3-chloro-5-nitro-1,2,4- research groups.5a,6,7,8a,8b N-amino azo-coupling products of
triazole) (ABCNT), and the azidation product of ABCNT, 1,10- substituted 1,2,4-triazole, however, have not been fully explored
and fully characterized.8b 3,5-dinitro-1,2,4-triazole (DNT) reac-
ted with potassium hydroxide ethanol solution to produce
potassium 3,5-dinitro-1,2,4-triazolate (KDNT), followed by
amination reaction with the MSH as the N-amination agent to
yield N-amino compound 1-amino-3,5-dinitro-1,2,4-triazole
(ADNT). Treatment of an acetonitrile solution of ADNT with
tert-butyl hypochlorite (t-BuOCl) led to obtain two different
compounds. When the molar ratio of t-BuOCl and ADNT was
1.3 : 1, the azo coupling product was 1,10-azobis(3,5-dinitro-
1,2,4-triazole) (ABDNT). When the molar ratio of t-BuOCl and
ADNT was more than 2.5 : 1, the azo coupling product was 1,10-
azobis(3-chloro-5-nitro-1,2,4-triazole) (ABCNT); the chlorine
atoms and nitro groups in ABCNT are certainly activated and are
Scheme 2 Examples of reported high-nitrogen compounds with
N,N0-azo linkage.
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Scheme 3 Synthesis routes of N-amination agents.
reacted with nucleophiles. The chlorine atoms and nitro groups IS ¼ 7.4 J, FS ¼ 112 N), which suggest that they can serve as
in compound ABCNT were substituted with azide groups by promising candidates for safe energetic materials. All the novel
reaction with sodium azide to produce 1,10-azobis(3,5-diazido- catenated N6 energetic derivatives based on ADNT are less
1,2,4-triazole) (ABDAT). The synthetic pathways to ADNT and sensitive than the reported high-nitrogen compounds with
its all energetic derivatives are depicted in Scheme 4. The N,N0-diazo-bridged compounds (N8 and N10 compounds).
structures of all compounds were fully characterized by IR
spectroscopy, DSC, 1H and 13C NMR spectroscopies and
elemental analysis. The data are listed in the Experimental
Physiochemical and detonation properties
The thermal stabilities of compounds ABDNT and ABDAT were
determined by differential scanning calorimetric (DSC)
measurements at a heating rate of 5 ꢁC minꢀ1. The thermal
decomposition peak temperatures of ABDNT and ABDAT were
section.
Sensitivities
To evaluate the stabilities of these N,N0-diazo-bridged energetic 262.4 ꢁC and 168.8 ꢁC (seen in Table 1), respectively, compared
compounds, we studied the impact and friction sensitivities. with that of traditional energetic compound RDX (239.2 ꢁC).
The sensitivities of all explosives were determined experimen- Because of the existence of the four azide groups in one
tally according to standard BAM methods.11 As can be seen in molecular structure, compound ABDAT has lower decomposi-
ꢁ
Table 1, The impact sensitivities of these energetic derivatives tion temperature (168.8 C). However, the decomposition peak
range from 6 J to 20 J. The value of friction sensitivities are from temperatures of ABDNT and ABDAT are much higher than those
+
80 N to 300 N. The compounds ABDNT and ABCNT are of hexazene (N6) ligand (140 C) and N5 (70 ꢁC).12
ꢁ
considerably less sensitive toward impact and friction sensi-
Densities of these energetic compounds which are in the
tivities than RDX and HMX (RDX: IS ¼ 7.4 J, FS ¼ 120 N; HMX: range of 1.71 to 1.93 g cmꢀ3 were determined using gas
Scheme 4 The synthetic pathways of energetic derivatives based on ADNT.
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Table 1 Physiochemical and detonation properties of novel catenated N6 energetic derivatives based on ADNT
Compound
ABDNT(N6)
ABCNT(N6)
ABDAT(N6)
6(N8)
7(N10
80
ꢀ48.2
84.3
1.77
1030.0
9.18
36.1
—
)
8(N10
)
9(N10
)
TNT
RDX
HMX
a
Tdec (ꢁC)
262.4
0
—
168.8
ꢀ39.0
85.3
1.71
2150.8
8.22
29.6
6629
6
187.5
ꢀ97.6
68.3
1.62
962.3
7.76
25.2
—
50
0
65.6
1.80
1153.0
9.18
112.5
ꢀ90.7
72.1
1.48
986.1
7.32
21.0
5078
—
295.0
ꢀ74.0
18.5
1.65
ꢀ115.0
6.88
19.5
4222
15
239.2
ꢀ21.6
37.8
1.82
92.6
8.71
33.7
5355
7.4
287.0
ꢀ21.6
37.8
1.90
104.8
9.10
39.6
5695
7.4
OBb (%)
ꢀ25.4
43.4
1.92k
774.8
8.83
35.8
6283
20
Nc (%)
48.8
1.93
973.9
9.49
42.4
7476
10
r
d (g cmꢀ3
)
DHfe (kJ molꢀ1
)
Df (km sꢀ1
Pg (GPa)
)
39.0
Qh (kJ kgꢀ1
ISi (J)
)
6931
01
05
4.1
—
ꢂ1
FSj (N)
160
300
80
ꢂ5
—
353
120
112
a
Thermal decomposition temperature. b Nitrogen content. c Oxygen balance (based on CO2) for CaHbOcNd, 1600(cꢀ2aꢀb/2)/MW, MW ¼ molecular
d
e
f
g
h
i
weight. Density measured by gas pycnometer. Heat of formation. Detonation velocity. Detonation pressure. Heat of detonation. Impact
sensitivity. j Friction sensitivity. k Single crystal density (296 K).
pycnometer or single-crystal X-ray diffraction. It is noteworthy
that the densities of compounds ABDNT and ABCNT fall in the
range designated for new HEDMs (1.8–2.0 g cmꢀ3),13 which are
higher than RDX (1.82 g cmꢀ3). Moreover, the high densities of
ABDNT (1.93 g cmꢀ3) and ABCNT (1.92 g cmꢀ3) are even
comparable with that of HMX (1.90 g cmꢀ3).
X-Ray crystallography
A single crystal of compound ABCNT suitable for crystal struc-
ture analysis was obtained by slow evaporation from acetonitrile
solution of ABCNT at room temperature. The crystal data and
structure renement details of ABCNT are given in Table 2. The
crystal structure of ABCNT adopts a planar structure with two
almost planar 3-chloro-5-nitro-1,2,4-triazole rings, a planar N6
chain and an E conguration about the azo bond (Fig. 1). The
azo bond adopts a stable E conguration due to lower active
energy than the Z conguration. The bond length between the
Heats of formation are one of the important characteristics
for energetic compounds and are directly related to the number
of nitrogen–nitrogen bonds in molecular structures. The stan-
dard enthalpies of formation for these derivatives were calcu-
lated by using the Gaussian 09 (Revision A. 02)14 suite of
programs and atomization method based on CBS-4M
enthalpies.15 All of the optimized structures were character-
ized to be true local energy minima on the potential-energy
surface without imaginary frequencies. As shown in Table 1,
the solid phase heats of formation for N,N0-diazo-bridged
energetic derivatives based on ADNT are highly endothermic
compounds. All of these compounds exhibit higher positive
ꢀ
N-atoms of the azo group (N1]N1A) is 1.240 A, shorter than
that of compound 5 with the N4 structure (1.249 A), compound 6
with the N8 structure (1.250 A) and compound 9 with the N10
ꢀ
ꢀ
ꢀ
structure (1.243 A), which indicates a stronger delocalization of
the nitro p3 (ref. 4) conjugated bond and azo p-bond along the
molecular structure within compound 6. But longer than that of
N4H4 (2-tetrazene)17 with the N4 structure (1.205 A) and
compound 7 with the N10 structure (1.178 A), respectively. This
is probably due to the electron-withdrawing property of the
nitro groups.
ꢀ
ꢀ
heats of formation ranging between 774.8 and 2150.8 kJ molꢀ3
,
which are compared with those of RDX (92.6 kJ molꢀ3), HMX
(104.8 kJ molꢀ3), and other reported catenated nitrogen-atom
compounds (N8 and N10 structures in Table 1). Especially,
compound ABDAT exhibits the highest heat of formation
(2150.8 kJ molꢀ1) among of them because of four azido-
functionalization groups in the same molecular structure.
Based on the calculated values of heats of formation and the
experimental values for the densities of these energetic deriva-
tives, the detonation velocities (D) and detonation pressures (P)
were calculated using the Kamlet–Jacobs equations.16 The
detonation velocities (D) lie between 8.22 and 9.49 km sꢀ1
(compared with TNT 6.88 km sꢀ1, and RDX 8.71 km sꢀ1).
Detonation pressures of these compounds lie in the range
between 29.6 to 42.4 GPa (compared with TNT 19.5 GPa, and
RDX 33.7 GPa). Compound ABDNT has the highest detonation
velocity (9.49 km sꢀ1) and detonation pressure (42.4 GPa),
which are also higher than other reported N,N0-diazo-bridged
energetic compounds (N8 and N10 structures). Although not
all these energetic derivatives perform better than RDX by
calculations, they can probably nd use in certain applications
in civilian use or in military applications.
Table 2 Crystal data and structure refinement details of ABCNT
Compounds
Empirical formula
Formula weight
CCDC number
T (K)
ABCNT
C4N10O4Cl2
323.04
1826501
296(2)
ꢀ
l (A)
0.71073
Monoclinic
Crystal system
Space group
Unit cell dimensions (A,
P21/c
ꢁ
ꢀ
)
a ¼ 8.844(5), a ¼ 90
b ¼ 15.589(9), b ¼ 105.495(11)
c ¼ 8.401(5), g ¼ 90
ꢀ3
V (A )
1116.2(12)
Z
4
Dc (g cmꢀ3
)
1.922
0.619
640
1.001
Absorption coefficient (mmꢀ1
F (000)
)
Goodness-of-t on F2
Final R indices (I > 2s(I))
R1 ¼ 0.0536, wR2 ¼ 0.1352
ꢀꢀ3
Largest diff. peak and hole (e A
)
0.302 and ꢀ0.378
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mL minꢀ1. About 0.5–1.0 mg of the sample was sealed in
aluminium pans for DSC. For all energetic materials, the impact
sensitivity were determined with a ZBL-B impact sensitivity
instrument, the friction sensitivity were determined with
a FSKM 10 friction sensitivity instrument. Energetic properties
have been calculated with Gaussian 09 program14 and Kamlet–
Jacobs equations16 using the calculated solid state heat of
formation and experimental value of density. These were
computed by the atomization method as described in published
papers.
X-ray crystallography
Single crystal suitable of compound ABCNT for X-ray measure-
ment was obtained by slow evaporation of acetonitrile solution
of ABCNT at room temperature. The crystal structure of ABCNT
was determined by a Bruker SMART APEXII CCD X-ray diffrac-
tometer and the SHELXTL crystallographic soware package. A
single crystal was mounted on a Bruker SMART APEXII CCD X-
ray diffractometer equipped with graphite-monochromatized
ꢀ
Mo-Ka radiation (0.71073 A). Data were collected by the u
scan technique. The structure was solved by direct methods
using SHELXS-97 program18 and rened against F2 by full-
matrix least-squares using SHELXL-97 program.19
Theoretical study
All the quantum computations were performed using the
Gaussian 09 (Revision A. 02) suite of programs.14 The optimized
structures were characterized to be true local energy minima on
the potential-energy surface without imaginary frequencies. The
room-temperature gas-phase enthalpies of all energetic
compounds were obtained by the atomization method based on
CBS-4M calculated electronic enthalpies using NIST20 values as
standardized values for the standard heats of formation (DHfꢁ).
Oen the standard state of the materials of interest corresponds
to the solid phase. Thus, the solid state enthalpies of formation
can be determined using the gas-phase enthalpy of formation
and enthalpy of sublimation phase transition according to the
Hess' law of constant heat summation as the eqn (1).21
Fig. 1 (a) X-ray structure of ABCNT with thermal ellipsoids at 50%
probability. (b) Packing diagram of ABCNT viewed down the a axis.
Experimental
Caution
Although we experienced no problems during the synthesis of
the target compounds, standard safety precautions (leather
gloves, face shield and ear plugs) should be used when handling
these energetic materials.
DH (solid) ¼ DH (gas) ꢀ DH (sublimation)
(1)
Based on the electrostatic potential of a molecule by
quantum mechanical prediction, the heat of sublimation can be
represented as the eqn (2).22
General methods
DH (sublimation) ¼ a(SA)2 + b(sTot2n)1/2 + c
(2)
All chemical reagents and solvents (analytical grade) were used
2
as supplied unless otherwise stated. Infrared spectra were ob- where, (SA) is the molecular surface area for this structure, sTot
tained from KBr pellets on a Nicolet NEXUS870 Infrared spec- is described as an indicator of the variability of the electrostatic
trometer in the range of 4000–400 cmꢀ1. 1H NMR and 13C NMR potential on the molecular surface, n is interpreted as showing
were obtained in DMSO-d6 on a Bruker AV500 NMR spectrom- the degree of balance between the positive and negative
eter. Elemental analyses (C, H and N) were performed on potentials on the molecular surface and a, b, and c are the tting
a VARI-El-3 elementary analysis instrument. Mass spectra were parameters. We further followed the approach of Politzer to
acquired using a GCMS-QP 2010 Micromass UK spectrometer. predict the heats of sublimation of energetic materials, and
The DSC experiment was performed using a DSC-Q 200 appa- then combined these with eqn (1) and (2) to predict the solid
ratus (TA, USA) under a nitrogen atmosphere at a ow rate of 50 enthalpies of formation.
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The empirical Kamlet–Jacobs (K–J) equations16 widely 1192, 1051, 959 cmꢀ1. Anal. calcd for C10H11N3O8S: C 36.04, H
employed to evaluate the energy performance of energetic 3.33, N 12.61%; found C 36.24, H 3.24, N 12.71%.
compounds were used to estimate the detonation velocity (D)
Compound D. Yellowish solid, with a yield of 70.9%. 1H
and detonation pressure (P) of all target compounds. Empirical NMR ([D6]DMSO, 500 MHz, 25 ꢁC, TMS): d ¼ 1.20 (t, 3H), 2.05 (s,
Kamlet–Jacobs (K–J) equations can be shown in eqn (3)–(5).
3H), 2.56 (s, 3H), 2.90 (s, 3H), 3.93 (t, 2H), 7.2 (d, 1H), 7.8 (d, 1H),
13
ꢁ
8.12 (s, 1H) ppm. C NMR ([D6]DMSO, 125 MHz, 25 C): d ¼
13.88, 14.76, 20.98, 22.64, 63.49, 129.13, 130.53, 133.24, 135.61,
141.67, 142.36, 170.31 ppm. IR (KBr pellet): n ¼ 2993, 2952,
1641, 1611, 1452, 1361, 1320, 1191, 971 cmꢀ1. Anal. calcd for
C12H17NO4S: C 53.12, H 6.32, N 5.16%; found C 53.23, H 6.23, N
5.27%.
P ¼ 1.558r2F
(3)
(4)
(5)
D ¼ 1.01F1/2(1.011 + 1.312r)
F ¼ 0.4889N(MQ)1/2
1
Compound E. White solid, with a yield of 95.6%. H NMR
where, D is the predicted detonation velocity (m sꢀ1), P is the
predicted detonation pressure (GPa), r is the density of explo-
sives (g cmꢀ3), N is the moles of detonation gases per gram
explosive, M is the average molecular weight of these gases, and
Q is the chemical energy of detonation (kJ gꢀ1). The densities
and the calculated heats of formation were used to compute the
D and P values.
([D6]DMSO, 500 MHz, 25 ꢁC, TMS): d ¼ 1.19 (t, 3H), 2.04 (s, 3H),
2.31 (s, 3H), 2.65 (s, 6H), 3.91 (t, 2H), 6.97 (s, 2H) ppm. 13C NMR
([D6]DMSO, 125 MHz, 25 ꢁC): d ¼ 13.98, 14.87, 21.07, 22.83,
63.61, 130.39, 131.52, 140.71, 143.32, 169.24 ppm. IR (KBr
pellet): n ¼ 2981, 2941, 1636, 1605, 1454, 1365, 1316, 1180, 1054,
962, 851 cmꢀ1. Anal. calcd for C13H19NO4S: C 54.72, H 6.71, N
4.91%; found C 54.63, H 6.82, N 4.98%.
1
Compound F. White solid, with a yield of 91.1%. H NMR
General procedure for O-substituted benzenesulfonyl ethyl
acetohydroxamate (A–G)
ꢁ
([D6]DMSO, 500 MHz, 25 C, TMS): d ¼ 1.15 (m, 24H), 2.04 (s,
3H), 3.88 (t, 2H), 7.31 (s, 2H) ppm. 13C NMR ([D6]DMSO, 125
Ethyl acetohydroxamate (5.15 g, 50.0 mmol) was dissolved in MHz, 25 ꢁC): d ¼ 14.09, 15.12, 23.76, 24.29, 24.72, 25.27, 28.52,
N,N-dimethylformamide (25.0 mL) at room temperature, then 29.70, 33.91, 64.00, 121.87, 124.20, 129.06, 142.08, 147.30,
triethylamine (5.05 g, 50.0ꢁ mmol) was added dropwise. The 147.81, 151.28, 154.47, 169.59 ppm. IR (KBr pellet): n ¼ 2981,
mixture was kept at 20–25 C for another 10 minutes and was 2941, 1636, 1605, 1454, 1365, 1316, 1180, 1054, 962, 851 cmꢀ1
.
ꢁ
then cooled to 0–5 C. O-substituted benzenesulfonyl chloride Anal. calcd for C19H31NO4S: C 61.76, H 8.46, N 3.79%; found C
(50.0 mmol) was slowly added to the above cooled mixture while 61.87, H 8.35, N 3.86%.
maintaining the reaction temperature below 5 ꢁC. Aer
Compound G. Light-pink solid, with a yield of 85.2%. 1H
complete addition, the reaction mixture was stirred for 1 h at NMR ([D6]DMSO, 500 MHz, 25 ꢁC, TMS): d ¼ 1.35 (t, 3H), 2.23 (s,
10 ꢁC. When the reaction solution was poured into ice-water, 3H), 3.98 (t, 2H), 8.82 (s, 2H) ppm. 13C NMR ([D6]DMSO, 125
a solid precipitated. The solid was ltered off, washed with MHz, 25 ꢁC): d ¼ 14.14, 15.03, 64.34, 123.71, 139.87, 141.32,
cold water, and dried in air to give product O-substituted ben- 150.51, 170.26 ppm. IR (KBr pellet): n ¼ 3092, 2989, 2906, 1542,
zenesulfonyl ethyl acetohydroxamate.
1357, 1633 cmꢀ1. Anal. calcd for C10H10N4O8: C 38.23, H 3.21, N
Compound A. White solid, with a yield of 83.3%. H NMR 17.83%; found C 38.33, H 3.18, N 17.78%.
([D6]DMSO, 500 MHz, 25 ꢁC, TMS): d ¼ 1.15 (t, 3H), 2.09 (s, 3H),
1
3.92 (t, 2H), 7.95 (t, 1H), 8.05 (t, 1H), 8.12 (d, 1H), 8.17 (d,
General procedure for synthesis of N-amination agents
1H) ppm. 13C NMR ([D6]DMSO, 125 MHz, 25 ꢁC): d ¼ 14.19,
15.37, 64.54, 125.34, 126.72, 132.68, 133.19, 136.91, 148.48, O-Substituted benzenesulfonyl ethyl acetohydroxamate (5.0 g)
171.65 ppm. IR (KBr pellet): n ¼ 3101, 2992, 2946, 1620, 1538, was dissolved in 1,4-dioxane (20.0 mL) at room temperature and
1442, 1382, 1323, 1195, 1127, 1058, 956, 886, 826 cmꢀ1. Anal. was then cooled to 0–5 ꢁC. Then perchloric acid (70%ꢃ72%, 8.0
calcd for C10H12N2O6S: C 41.66, H 4.20, N 9.72%; found C 41.79, mL)ꢁwas slowly added dropwise to the above cooled mixture at
H 4.12, N 9.82%.
0–5 C. Aer complete addition, the reaction mixture was stir-
1
Compound B. White solid, with a yield of 75.0%. H NMR red for 0.5–1 h at 5–10 ꢁC. When the reaction solution was
([D6]DMSO, 500 MHz, 25 ꢁC, TMS): d ¼ 1.18 (t, 3H), 2.03 (s, 3H), poured into ice-water, a solid precipitated. The solid was ltered
3.96 (t, 2H), 8.00 (t, 1H), 8.39 (d, 1H), 8.58 (s, 1H), 8.63 (d, off, washed with cold water, and dried in air to give target.
1H) ppm. 13C NMR ([D6]DMSO, 125 MHz, 25 ꢁC): d ¼ 14.23,
Compound 2-NSH. Light-yellow solid, with a yield of 74.2%.
1
ꢁ
15.34, 64.47, 123.77, 129.64, 132.11, 134.85, 136.29, 148.36,
H NMR ([D6]DMSO, 500 MHz, 25 C, TMS): d ¼ 6.41 (s, 2H),
171.40 ppm. IR (KBr pellet): n ¼ 3104, 2993, 2953, 1632, 1534, 6.96 (d, 1H), 7.10 (d, 1H), 7.32ꢁ(t, 1H), 7.51 (d, 1H) ppm. 13C
1379, 1353, 1197, 1053 cmꢀ1. Anal. calcd for C10H12N2O6S: C NMR ([D6]DMSO, 125 MHz, 25 C): d ¼ 114.31, 121.60, 124.99,
41.66, H 4.20, N 9.72%; found C 41.58, H 4.32, N 9.61%.
130.69, 141.34, 150.10 ppm. IR (KBr pellet): n ¼ 3423, 3092,
Compound C. Light-yellow solid, with a yield of 70.9%. H 3016, 1554, 1510, 1459, 1374, 1274, 1243, 1130 cmꢀ1. Anal. calcd
1
NMR ([D6]DMSO, 500 MHz, 25 ꢁC, TMS): d ¼ 1.18 (t, 3H), 2.10 (s, for C6H6N2O5S: 33.03, H 2.77, N 12.84%; found C 33.20, H
3H), 3.93 (t, 2H), 8.42 (d, 1H), 8.66 (d, 1H), 9.02 (d, 1H) ppm. 13
C
2.84, N 12.92%.
NMR ([D6]DMSO, 125 MHz, 25 ꢁC): d ¼ 14.26, 15.48, 64.76,
Compound 3-NSH. Light-yellow solid, with a yield of 60.8%.
1
ꢁ
120.99, 127.63, 131.36, 134.57, 148.52, 151.66, 172.26 ppm. IR
H NMR ([D6]DMSO, 500 MHz, 25 C, TMS): d ¼ 6.18 (s, 2H),
(KBr pellet): n ¼ 3111, 3092, 2999, 1630, 1559, 1539, 1350, 1326, 7.68 (t, 1H), 8.04 (d, 1H), 8.21 (d, 1H), 8.36 (s, 1H) ppm. 13C NMR
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([D6]DMSO, 125 MHz, 25 ꢁC): d ¼ 120.53, 123.92, 130.30, 132.43, 500 MHz, 25 ꢁC, TMS): d ¼ 6.83 (s, 2H) ppm. 13C NMR ([D6]
147.70, 150.31 ppm. IR (KBr pellet): n ¼ 3396, 3244, 3097, 1609, DMSO, 125 MHz, 25 ꢁC): d ¼ 155.31, 155.92 ppm. IR (KBr pellet):
1536, 1350, 1239, 1193, 1043 cmꢀ1. Anal. calcd for C6H6N2O5S: C n ¼ 3424, 3340, 3297, 3229, 1671, 1520, 1313 cmꢀ1. Anal. calcd
33.03, H 2.77, N 12.84%; found C 33.15, H 2.67, N 12.75%.
for C2H2N6O4: C 13.80, N 48.28, H 1.16%; found C 13.96, N
Compound DNSH. Off-white solid, with a yield of 81.0%. 1H 48.01, H 1.22%. MS (m/z): 174.05 [M+].
ꢁ
NMR ([D6]DMSO, 500 MHz, 25 C, TMS): d ¼ 3.94 (s, 2H), 8.42
(d, 1H), 8.67 (d, 1H), 9.03 (d, 1H) ppm. 13C NMR ([D6]DMSO, 125
MHz, 25 ꢁC): d ¼ 120.98, 127.61, 131.38, 134.58, 148.52, 1,10-Azobis(3,5-dinitro-1,2,4-triazole) (ABDNT)
151.65 ppm. IR (KBr pellet): n ¼ 3412, 3273, 3102, 1612, 1539,
ADNT (0.1 g, 0.58 mmol) was dissolved in anhydrous acetoni-
1358, 1241, 1045, 884 cmꢀ1. Anal. calcd for C6H5N3O7S: C 27.38,
H 1.91, N 15.97%; found C 27.51, H 1.83, N 16.04%.
trile (10.0 mL) under the existence of nitrogen gas at room
temperature, then tert-butyl hypochlorite (t-BuOCl) (0.082 g,
0.75 mmol) was slowly added dropwise at 0–5 ꢁC. Aer complete
Compound DMSH. White solid, with a yield of 70.3%. 1H
NMR ([D6]DMSO, 500 MHz, 25 ꢁC, TMS): d ¼ 2.17 (s, 3H), 2.53 (s,
ꢁ
addition, the mixture was stirred at 20–25 C for another 20 h,
3H), 6.76 (s, 2H), 7.32 (d, 1H), 7.76 (d, 1H), 8.03 (s, 1H) ppm. 13
C
evaporated acetonitrile under reduced pressure, and triturated
with isopropyl alcohol (1.5 mL). The precipitate was ltered off,
washed with isopropyl alcohol and ice-water, and dried to give
41.0 mg yellow solid ABDNT with a yield of 41.5%. 13C NMR
NMR ([D6]DMSO, 125 MHz, 25 ꢁC): d ¼ 21.07, 23.54, 129.91,
130.43, 134.52, 137.87, 142.82, 144.79 ppm. IR (KBr pellet): n ¼
3339, 3268, 3036, 2985, 2947, 781, 688 cmꢀ1. Anal. calcd for
C8H11NO3S: C 47.75, H 5.51, N 6.96%; found C 47.86, H 5.42, N
7.05%.
ꢁ
([D6]DMSO, 125 MHz, 25 C): d ¼ 133.45, 141.66 ppm. IR (KBr
pellet): n ¼ 1661, 1657, 1570, 1371, 1329, 1397, 1250, 1122,
1012 cmꢀ1. Anal. calcd for C4N12O8: C 13.96, N 48.84%; found C
13.87, N 48.91%. MS (m/z): 344.06 [M+].
Compound MSH. White solid, with a yield of 74.3%. 1H NMR
([D6]DMSO, 500 MHz, 25 ꢁC, TMS): d ¼ 2.18 (s, 3H), 2.51 (s, 6H),
6.77 (s, 2H), 9.24 (s, 2H) ppm. 13C NMR ([D6]DMSO, 125 MHz, 25
ꢁC): d ¼ 20.76, 23.18, 130.45, 136.42, 137.14, 142.63 ppm. IR
(KBr pellet): n ¼ 3340, 3270, 3035, 2987, 2945, 779, 689 cmꢀ1
.
1,10-Azobis(3-chloro-5-nitro-1,2,4-triazole) (ABCNT)
Anal. calcd for C9H13NO3S: C 50.21, H 6.09, N 6.51%; found C
50.33, H 6.15, N 6.44%. MS (m/z): 214.10 [M ꢀ H]ꢀ.
ADNT (0.174 g, 1.0 mmol) was dissolved in anhydrous aceto-
nitrile (15.0 mL) under the existence of nitrogen gas at room
temperature, then tert-butyl hypochlorite (t-BuOCl) (0.273 g, 2.5
mmol) was slowly added dropwise at 0–5 ꢁC. Aer complete
Compound TSH. White solid, with a yield of 91.4%. 1H NMR
ꢁ
([D6]DMSO, 500 MHz, 25 C, TMS): d ¼ 1.12 (d, 12H), 1.17 (d,
6H), 2.81 (t, 1H), 4.53 (t, 2H), 6.98 (s, 2H), 9.59 (s, 2H) ppm. 13
C
ꢁ
addition, the mixture was stirred at 20–25 C for another 20 h,
NMR ([D6]DMSO, 125 MHz, 25 ꢁC): d ¼ 24.78, 25.26, 28.59,
33.75, 66.83, 121.99, 141.57, 147.37, 148.12 ppm. IR (KBr pellet):
n ¼ 3333, 3265, 3187, 2960, 2870, 1637, 1599, 1461, 1378, 1318,
1182, 1086, 1014, 881 cmꢀ1. Anal. calcd for C15H25NO3S: C
60.17, H 8.42, N 4.68%; found C 60.37, H 8.35, N 4.73%.
Compound PHA. Yellow solid, with a yield of 82.9%. 1H NMR
([D6]DMSO, 500 MHz, 25 ꢁC, TMS): d ¼ 5.00 (s, 2H), 9.01 (s, 1H),
then ethyl acetate (30.0 mL) was added, washed organic phase
with ice-water, dried with magnesium sulfate, evaporated
organic solvent under reduced pressure and dried in air to
obtain 0.113 g light-yellow solid ABCNT with a yield of 65.7%.
13C NMR ([D6]DMSO, 125 MHz, 25 ꢁC): d ¼ 141.73, 158.73 ppm.
IR (KBr pellet): n ¼ 1650, 1574, 1507, 1446, 1388, 1347, 1303,
1242, 1218, 1097, 1000, 844, 743 cmꢀ1. Anal. calcd for
C4N10O4Cl2: C 14.87, N 43.36%; found C 14.93, N 43.29%.
13
ꢁ
9.04 (s, 1H) ppm. C NMR ([D6]DMSO, 125 MHz, 25 C): d ¼
124.08, 125.39 ppm. IR (KBr pellet): n ¼ 3331, 3303, 3266, 3084,
1552, 1540, 1360, 1341 cmꢀ1. Anal. calcd for C6H6N4O7: C 29.52,
H 1.65, N 22.95%; found C 29.43, H 1.72, N 22.88%. MS (m/z):
243.06 [M ꢀ H]ꢀ.
1,10-Azobis(3,5-diazido-1,2,4-triazole) (ABDAT)
ADNT (0.174 g, 1.0 mmol) was dissolved in anhydrous aceto-
nitrile (15.0 mL) under the existence of nitrogen gas at room
temperature, then tert-butyl hypochlorite (t-BuOCl) (0.273 g, 2.5
1-Amino-3,5-dinitro-1,2,4-triazole (ADNT)
3,5-Dinitro-1,2,4-triazole (DNT) (2.0 g, 0.13 mol) was dissolved mmol) was slowly added dropwise at 0–5ꢁ ꢁC. Aer complete
in ethanol (15.0 mL) at room temperature, then potassium addition, the mixture was stirred at 20–25 C for another 20 h,
hydroxide (5%, 14.2 g, 0.13 mol) was added dropwise at 5–10 ꢁC. then ethyl acetate (30.0 mL) was added, washed organic phase
Aer 1 h at room temperature, the precipitate was ltered off, with ice-water, dried with magnesium sulfate, evaporated
washed with ethanol and ice-water, and dried in air to give organic solvent under reduced pressure and dried in air to
yellow solid potassium 3,5-dinitro-1,2,4-triazolate (KDNT). obtain 0.113 g light-yellow solid ABCNT with a yield of 65.7%.
KDNT (1.0 g, 5.1 mmol) was dispersed in anhydrous acetonitrile 13C NMR ([D6]DMSO, 125 MHz, 25 ꢁC): d ¼ 151.65, 157.41 ppm.
14
ꢁ
(40.0 mL) at room temperature. A solution of MSH (1.62 g, 7.5
N NMR ([D6]DMSO, 60 MHz, 25 C): d ¼ ꢀ275.12, ꢀ229.05,
mmol) and acetonitrile (10.0 mL) was added dropwise for 0.5 h. ꢀ145.99, ꢀ145.17, ꢀ142.52, ꢀ130.17, ꢀ68.91, ꢀ1.382 ppm. IR
Aer complete addition, the mixture was stirred at 20–25 ꢁC for (KBr pellet): n ¼ 2405, 2288, 2208, 2182, 2155, 1542, 1515, 1406,
another 10 h, evaporated organic solvent under reduced pres- 1343, 1291, 1212, 1200, 1086, 999 cmꢀ1. Anal. calcd for C4N20: C
sure, recrystallized from acetone, dried in air to obtain 0.73 g 14.64, N 85.36%; found C 14.76, N 85.21%. MS (m/z): 351.10 [M
yellow solid ADNT with a yield of 82.6%. H NMR ([D6]DMSO, + Na]+.
1
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¨
¨
M. Gobel, K. Karaghiosoff, T. M. Klapotke, D. G. Piercey
and J. Stierstorfer, J. Am. Chem. Soc., 2010, 132, 17216–17226.
4 (a) M. H. V. Huynh, M. A. Hiskey, D. E. Chavez, D. L. Naud
and R. D. Gilardi, J. Am. Chem. Soc., 2005, 127, 12537–
12543; (b) T. Abe, G. Tao, Y. H. Joo, Y. Huang, B. Twamley
and J. M. Shreeve, Angew. Chem., 2008, 120, 7195–7198.
5 (a) C. Qi, S. Li, Y. Li, Y. Wang, X. Chen and S. Pang, J. Mater.
Chem., 2011, 21, 3221–3225; (b) D. L. Naud, M. A. Hiskey and
H. H. Harry, J. Energ. Mater., 2003, 21, 57–62; (c) D. E. Chavez,
M. A. Hiskey and R. D. Gilardi, Angew. Chem., Int. Ed., 2000,
39, 1791–1793; (d) M. H. V. Huynh, M. A. Hiskey,
E. L. Hartline, D. P. Montoya and R. Gilardi, Angew. Chem.,
Int. Ed., 2004, 43, 4924–4928.
Conclusions
Three novel catenated N6 energetic derivatives based on 1-
amino-3,5-dinitro-1,2,4-triazole (ADNT), which contain 1,10-
azobis(3,5-dinitro-1,2,4-triazole) (ABDNT), 1,10-azobis(3-chloro-
5-nitro-1,2,4-triazole) (ABCNT) and 1,10-azobis(3,5-diazido-
1,2,4-triazole) (ABDAT), were prepared and fully characterized
by using IR and NMR spectroscopies, elemental analysis, mass
spectra, and single-crystal X-ray diffraction analysis for ABCNT.
These energetic derivatives exhibit acceptable thermal stabili-
ties (168.8–262.4 ꢁC). Densities for these compounds fall in the
range between 1.71 and 1.93 g cmꢀ3. All of the compounds
exhibit higher positive heats of formation ranging between
774.8 and 2150.8 kJ molꢀ3. Especially, compound ABDAT
exhibits the highest heat of formation (2150.8 kJ molꢀ1), which
is higher than other reported catenated nitrogen-atom
compounds. Their detonation properties were evaluated by
Gaussian 09 and Kamlet–Jacobs equations. The calculated
detonation velocities (8.22–9.49 km sꢀ1) and detonation pres-
sures (29.6–42.4 GPa) are comparable to those of explosives
such as TNT (6.88 km sꢀ1, 19.5 GPa) and RDX (8.71 km sꢀ1, 33.7
GPa). Most of these compounds have reasonable impact sensi-
tivities (6 to 20 J) and friction sensitivities (80 to 300 N), which
suggest that they have the potential to be useful new energetic
materials.
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Conflicts of interest
There are no conicts to declare.
´
´
9 W. A. Trzcinski, S. Cudzilo, Z. Chylek and L. Szymanczyk, J.
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Financial support of this work by the National Natural Science
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