Synthesis of nitrogen-rich imidazole, 1,2,4-triazole and tetrazole-based compounds

Article abstract of DOI:10.1039/c3ra47227b

Imidazole, 1,2,4-triazole and tetrazole based molecules were prepared for their possible applications in nitrogen-rich gas generators. The energetic salts of 1-(1H-1,2,4-triazol-3-yl)-1H-tetrazole (9), 5-(1H-tetrazol-1-yl)-1H-1,2,4- triazol-3-amine (10), 1-(3-azido-1H-1,2,4-triazol-5-yl)-1H-tetrazole (11) and 3-azido-1H-1,2,4-triazol-5-amine (12) were prepared with various cationic moieties. Their densities, heats of formation, chemical energy of detonation, detonation velocities and pressures were calculated. All of the compounds possessed high positive heats of formation due to high energy contribution from the molecular backbone of the corresponding compounds. The effect of the azole rings and nitro, amino, and azido groups on their physicochemical properties was examined and discussed. The Royal Society of Chemistry 2014.

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Entry for the Table of Contents
A library of nitrogen-rich compounds
has been synthesized via simple and
straightforward approach for the
possible applications in high energy
materials. Their performance has been
evaluated by calculating their densities,
heats of formation, chemical energy of
detonation, detonation velocities and
pressures. The effect of the azole rings
and nitro, amino, and azido groups on
their physicochemical properties was
also examined.
Dharavath Srinivas, Vikas D. Ghule,
Krishnamurthi Muralidharan* ……..

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ARTICLE TYPE
Synthesis of nitrogen-rich imidazole, 1,2,4-triazole and tetrazole-based
compounds
Dharavath Srinivas,a Vikas D. Ghule,b Krishnamurthi Muralidharan*a,c
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX
5
DOI: 10.1039/b000000x
Imidazole, 1,2,4ꢀtriazole and tetrazole based molecules were prepared for their possible applications in
nitrogenꢀrich gas generators. The energetic salts of 1ꢀ(1Hꢀ1,2,4ꢀtriazolꢀ3ꢀyl)ꢀ1Hꢀtetrazole (9), 5ꢀ(1Hꢀ
tetrazolꢀ1ꢀyl)ꢀ1Hꢀ1,2,4ꢀtriazolꢀ3ꢀamine (10), 1ꢀ(3ꢀazidoꢀ1Hꢀ1,2,4ꢀtriazolꢀ5ꢀyl)ꢀ1Hꢀtetrazole (11) and 3ꢀ
azidoꢀ1Hꢀ1,2,4ꢀtriazolꢀ5ꢀamine (12) were prepared with various cationic moieties. Their densities, heats
10 of formation, chemical energy of detonation, detonation velocities and pressures were calculated. All of
the compounds possessed high positive heats of formation due to high energy contribution from the
molecular backbone of the corresponding compounds. The effect of the azole rings and nitro, amino, and
azido groups on their physicochemical properties was examined and discussed.
introduction of nitro, azido or azo groups, salt formation and Nꢀ
oxidation in tetrazole have been developed to improve the
properties of tetrazoleꢀbased energetic materials. Due to high
50 nitrogen content and consequently high average two electron
bond energy associated with the NꢀN triple bond formation, these
compounds have variety of applications as lowꢀsmoke producing
pyrotechnic compositions,4 gas generators,5 propellants,6 and
high explosives.7 Gas generators are used to generate large
55 amount of gas, as for turbopumps, to inflate balloons, especially
airbags, to eject parachutes, and for similar applications.
Herein, we report the synthesis of energetic salts based on the
1ꢀ(1Hꢀ1,2,4ꢀtriazolꢀ3ꢀyl)ꢀ1Hꢀtetrazole (9), 5ꢀ(1Hꢀtetrazolꢀ1ꢀyl)ꢀ
1Hꢀ1,2,4ꢀtriazolꢀ3ꢀamine (10), 1ꢀ(3ꢀazidoꢀ1Hꢀ1,2,4ꢀtriazolꢀ5ꢀyl)ꢀ
60 1Hꢀtetrazole (11) and 3ꢀazidoꢀ1Hꢀ1,2,4ꢀtriazolꢀ5ꢀamine (12)
anions. The presence of high nitrogen content and higher
enthalpy of formation of molecules containing 1,2,3ꢀtriazoles and
tetrazoles in their molecular structure would enable their use as
high enthalpy modifiers in energetic materials. Further, in the
65 recent literature, to the best of our knowledge, there is no report
available exploring the synthesis of these molecules and their
utility as possible nitrogenꢀrich energetic materials.
Introduction
15 In recent years, the development of heterocyclic based energetic
compounds has attracted much attention, since these compounds
offer a high positive heat of formation, density and better oxygen
balance than their hydrocarbon analogs.1 Apart from high heats of
formation,
nitrogenꢀrich
compounds
mainly
generate
20 environmentally friendly molecular nitrogen as a major endꢀ
product of combustion or explosion. Performance and safety
during handling and usage are the most important concern in the
development of energetic materials, but there is an essential
contradiction between them. For example, the wellꢀknown cage
25 and strained energetic material, CLꢀ20 exhibit very high density
(ρ=2.04 g/cm3) and detonation performance (D=9.5 km/s and
P=45 GPa), however tend to be sensitive towards impact or
friction or external stimuli, whereas the less energetic materials
like TNT or TATB show the opposite trend. The power of
30 energetic materials is strongly dependent on its molecular
structure and chemical substituents on it. But their safety
mechanism is much more complicated and controlled by many
factors. Fiveꢀmembered nitrogenꢀcontaining heterocycles such as
imidazole, pyrazole, triazole and tetrazole are known as
35 traditional source of energetic materials. They are at the forefront
of high energy materials research and expected to achieve
increasing performance requirements with reasonable safety.2
Among these heterocyclic compounds, tetrazole is a powerful
building block for high energy density materials (HEDMs) due to
40 its high nitrogen content (~80%), high positive heat of formation
(320 kJ/mol), low sensitivity towards impact and good thermal
Results and discussion
The energy content associated with the five membered azole
70 rings makes them more essential in design and synthesis of high
energy materials. The hydrogen atoms in azole rings can be
substituted by amino, nitro, or azide groups to enhance their
energy content and detonation performance. In this work, we are
reporting the synthesis of 5ꢀaminotetrazole (1) from cyanamide in
stability due to its aromatic ring system.3 This allows substitution 75 good yield (Scheme 1). Previously, 5ꢀaminotetrazole was
of various energetic groups or designing of compounds with
varying performance and sensitivity. Due to its significant
prepared from different starting materials and its derivatives were
extensively studied for their applications in energetic materials
due to their high nitrogen contents and better thermal stability.8
The cyanamide to 5ꢀaminotetrazole conversion was carried out as
45 energetic properties,
a variety of tetrazoleꢀbased energetic
compounds have already been synthesized. Moreover,
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described by Das et al9 using sodium azide and iodine in DMF
and subsequent treatment with HCl.
The presence of two or more azole rings is always desirable in
energetic backbone to improve its thermal stability and energy
content.11 Moving from imidazole to triazole to tetrazole,
improves nitrogen content, heat of formation and oxygen balance.
35 The heats of formation for imidazole, 1,2,4ꢀtriazole, and tetrazole
are 129, 192 and 326 kJ/mol, respectively12 and their
corresponding nitrogen contents are 41, 61, and 80%. Thus, when
1Hꢀ1,2,4ꢀtriazolꢀ3ꢀamine and 1Hꢀ1,2,4ꢀtriazoleꢀ3,5ꢀdiamine were
reacted with triethylorthoformate and sodium azide in acetic acid
40 produced 1ꢀ(1Hꢀ1,2,4ꢀtriazolꢀ3ꢀyl)ꢀ1Hꢀtetrazole (9) and 5ꢀ(1Hꢀ
Scheme 1. Synthesis of 5ꢀaminotetrazole (1).
5
High performance and low sensitivity tend to be contradicting
aspects; hence it is hard to fulfil all the requirements for new
energetic materials. However, incorporation of azole rings into a
compound is also a known strategy for increasing thermal
stability and plays a very important role in designing new
tetrazolꢀ1ꢀyl)ꢀ1Hꢀ1,2,4ꢀtriazolꢀ3ꢀamine
(10),
respectively
(Schemes 3 and 4). The reaction of 1Hꢀ1,2,4ꢀtriazoleꢀ3,5ꢀdiamine
with excess triethylorthoformate and sodium azide failed to
convert both amino groups to tetrazole rings (13). 10 reacted with
45 tertꢀbutyl nitrite and azidotrimethylsilane to form 1ꢀ(3ꢀazidoꢀ1Hꢀ
1,2,4ꢀtriazolꢀ5ꢀyl)ꢀ1Hꢀtetrazole (11). 3ꢀAzidoꢀ1Hꢀ1,2,4ꢀtriazolꢀ5ꢀ
amine (12) was synthesized in excellent yield from 1Hꢀ1,2,4ꢀ
triazoleꢀ3,5ꢀdiamine by following a procedure reported by
Kofman and Namestnikov13 reported using sodium nitrite and
50 sodium azide.
10 potential HEMs. As a result, we have synthesized different
nitrogenꢀrich compounds. Scheme 2 represents the synthesis of
various imidazoleꢀtetrazole based compounds. The 2ꢀnitroꢀ1Hꢀ
imidazoleꢀ4,5ꢀdicarbonitrile (3) was obtained from 2ꢀaminoꢀ1Hꢀ
imidazoleꢀ4,5ꢀdicarbonitrile (2) with excess treatment of sodium
15 nitrite.10 Similarly, 2 was treated with sodium nitrite followed by
sodium azide to get 2ꢀazidoꢀ1Hꢀimidazoleꢀ4,5ꢀdicarbonitrile (4).
The nitrile groups on imidazole backbone were converted easily
to tetrazole rings in high yields using sodium azide and iodine in
DMF to obtain 4,5ꢀdi(1Hꢀtetrazolꢀ5ꢀyl)ꢀ1Hꢀimidazolꢀ2ꢀamine (5)
20 and 1ꢀ[4,5ꢀdi(1Hꢀtetrazolꢀ5ꢀyl)ꢀ1Hꢀimidazolꢀ2ꢀyl]ꢀ1Hꢀtetrazole
(7). 2 reacted with triethylorthoformate and sodium azide in
acetic acid to produce 2ꢀ(1Hꢀtetrazolꢀ1ꢀyl)ꢀ1Hꢀimidazoleꢀ4,5ꢀ
dicarbonitrile (6) in good yield. To understand the effect of amide
group on energetic properties, we have converted nitrile group to
25 amide in 2ꢀaminoꢀ5ꢀcyanoꢀ1Hꢀimidazoleꢀ4ꢀcarboxamide (8). The
nitrile group of 8 could not be converted to tetrazole using similar
conditions of 5 and 7.
Compounds 9, 10, 11, and 12 were subsequently deprotonated
in alcoholic solution with concomitant formation of salts with
various molecules like guanidine, carbohydrazide, 4ꢀaminoꢀ4Hꢀ
1,2,4ꢀtriazole, 3ꢀaminoꢀ1,2,4ꢀtriazole, and 3,5ꢀdiaminoꢀ1,2,4ꢀ
55 triazole. The selected cationic moieties are presented in Scheme
5. These cationic moieties are wellꢀknown due to their energetic
properties and widely used in constructing the energetic salts. In
our previous work,14 we presented the molecular electrostatic
potential graphs to illustrate electrophilicity and nucleophilicity
60 in the selective anionic and cationic moieties. All compounds
were characterized by means of elemental analysis, mass
spectrometry (MS), IR and NMR (1H and 13C) spectroscopy. As
might be expected from the structural similarities between these
nitrogenꢀrich compounds, the vibration modes were also very
65 similar. In most of these azole compounds, the mostꢀimportant
vibrations are the NꢀH, CꢀN, C=C and N=N bond stretches. In
these compounds, NꢀH stretching found as an intense absorption
at 3100–3500 cm–1, CꢀN stretching observed in 1000ꢀ1300 cm–1,
and C=C bond stretching in 1600ꢀ1700 cm–1 region. Compounds
70 containing nitrile group (3, 4, 6, and 8) showed C≡N stretching in
the 2240ꢀ2260 cm–1 region. The amide linkage in 8 shows C=O
stretching at 3096ꢀ3447 cm–1 and NꢀH bending at 1577ꢀ1616 cm–
1 region. In the 1H NMR spectra, the proton signals of the anion 9
occurred at δ ≈10.12 and 8.88 ppm, for 10 anion, δ ≈9.92 and
75 6.65 ppm, for 11 anion, δ ≈10.10 ppm and for 12 anion, δ ≈6.27
ppm and the other signals are assigned to the respective cations.
We have also recorded the 1H NMR for 10 in D2O. The proton of
the NH (signal at δ 12.63 ppm) and –NH2 group (signal at δ 6.64
ppm) of 10 underwent rapid exchange with the protons in D2O as
1
80 shown in the H NMR spectrum. The signal at δ 9.91 ppm was
assigned to the proton of tetrazole ring. No signals were observed
in the 1H NMR spectrum that could be assigned to 10 supporting
the loss of proton(s). Similarly, in the 13C NMR spectra, the three
signals of the anion 9 observed at δ ≈152, 146, and 143 ppm, for
85 anion 10, three peaks occured at δ ≈157, 150, and 143 ppm, for
compound anion 11, signals δ ≈146, 143, and 134 ppm observed
and anion 12 spectra shows two signals at δ ≈157 and 154 ppm,
the remaining signals are associated with the cations. The high
30 Scheme 2. Synthesis of imidazole derivatives (3ꢀ8).
2
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resolution mass spectrum of salt 9a exhibited peak at m/z =
positive HOFs of 5 and 7 clearly reveals the role of tetrazole ring
in the improvement of HOF and their HOFs are 602 and 985
kJ/mol, respectively. Similarly, the calculated HOFs of 9, 10, 11
40 and 12 show high positive HOFs. Introduction of tetrazole and
azido group on the triazole backbone improves HOF
significantly. Comparing 9, 10 and 11 reveals that introduction of
amino group in molecular structure reduces the HOF, while
insertion of azido group improves HOF. The calculated HOFs of
45 salts are summarized in Table 2. All the salts possess high
positive HOFs, and salts of 11 have highest values due to
significant energy contribution from 11 anion (610.7 kJ/mol). The
calculated values of HOF range from 326ꢀ1032 kJ/mol.
Oxygen balance (OB) is an expression used to indicate the
50 degree, to which an explosive can be oxidized. Owing to the
absence of oxygen donor groups in anionic starting materials (5,
7, 9, 10, 11, and 12); all of them have negative OB and are in the
range from ꢀ63 to ꢀ91%. The nitrogen content is another very
important property in energetic materials. Compounds 5, 7, 9, 10,
55 11, and 12 have nitrogen content above 70%, and the salts paired
with triazole based cations possess nitrogen content in the range
67 to 75 %. One of the most important physical properties of a
solid energetic material is its density. The densities of were
calculated using the Hofmann approach16 and the results
60 summarized in Table 1. As shown in Table 2, the densities of
most of the salts range from 1.55 to 1.78 g/cm3. The detonation
parameters were calculated by Kamlet–Jacobs equations17 and
Table 2 shows that for salts, the calculated detonation pressures
(P) were in the range 14.7–27.2 GPa, and detonation velocity (D)
65 were in between 6.0–7.85 km/s, which are more or less close to
that of trinitrotoluene (TNT) (P=19.5 GPa, D= 6.8 km/s).
197.1009 (M+H) which found in good agreement with its actual
mass (m/z = 196.0933). The detailed analysis is presented in
experimental section.
5
Thermal stabilities and energetic properties
The thermal stabilities of all designed compounds were
determined by TGꢀDTA measurements at a heating rate of 10
°C/min. The melting points, thermochemical, and energetic data
of designed energetic salts are summarized in Table 2. As evident
10 from Table 2, compounds 5, 7, 9, 10, 11 and 12 decomposed
without melting, and the decomposition temperatures of these
compounds are in the range 173 to 238 °C representing good
thermal stability. Incorporation of amino group into a triazole
ring improves thermal stability as observed in 9 and 10. From
15 Table 2, the salts of 9, 10, 11, and 12 possess lower
decomposition temperature as compared to its nonionic
compounds. Among 9a to 9e salts 9c, decomposed without
melting, and its decomposition temperatures were found above
187 °C. In 10a-10e, 11e and 12a-12e salts, all compounds except
20 10e decompose without melting. 12a-12e salts showed
comparable decomposition temperature (~170 °C) to its nonionic
azido starting material, 12.
In this work, we have mainly focused on the synthesis and
characterization of tetrazole containing energetic materials to
25 improve nitrogen content and their heat of formation. The heat of
formation (HOF) is important parameter in evaluating the
performance of energetic materials and can be calculated with
good accuracy using isodesmic reactions and the lattice energy of
salts. The solid state HOF of 5, 7, 9, 10, 11, and 12 were
30 calculated from their gas phase HOF and heat of sublimation and
presented in Table 1. Calculations were carried out using the
Gaussian 03 suite of program.15 The structure optimization and
frequency analyses were carried out using B3PW91 functional
with the 6ꢀ31G(d,p) basis set. All of the optimized structures
35 were characterized to be true local energy minima on the
potentialꢀenergy surface without imaginary frequencies. The high
Scheme 3. Synthesis of 1ꢀ(1Hꢀ1,2,4ꢀtriazolꢀ3ꢀyl)ꢀ1Hꢀtetrazole (9) and
structure of its anionic substrate.
70
Scheme 4. Synthesis of nitrogenꢀrich triazoleꢀtetrazole based compounds and structure of their respective anions.
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Scheme 5. Selected nitrogenꢀrich cationic moieties for salt preparation.
5
Scheme 6. Isodesmic reactions designed for the prediction of the heats of formation.
Table 1. Energetic properties of nonionic compounds 5, 7 and 9-12.
c
d
e
HOFGas
HOFSub
HOFSolid
j
Compd
NCa (%)
OBb (%)
ρf (g/cm3)
Dg (km/s)
Ph (GPa)
Qi (cal/g)
Tdec
Mpk
(kJ/mol)
(kJ/mol)
749.8
(kJ/mol)
148.0
152.9
106.0
94.5
5
70.3
72.1
71.5
73.7
78.6
78.4
ꢀ91.3
ꢀ82.4
ꢀ87.6
ꢀ84.2
ꢀ62.9
ꢀ70.4
601.8
984.9
453.9
439.4
733.1
351.8
1.65
1.71
1.67
1.65
1.73
1.61
6.33
6.81
6.68
6.61
7.31
6.60
16.86
19.97
18.92
18.37
23.16
18.09
780
945
910
833
1045
802
227
7
1137.9
559.9
179
243
238
223
173
9
10
11
12
533.9
831.4
98.3
444.8
93.0
153
c
d
e
aNitrogen content (%). bOxygen balance (%). Heat of formation in gas phase (kJ/mol). Heat of sublimation (kJ/mol). Heat of formation in solid state
10 (kJ/mol). Density (g/cm3). Velocity of detonation (km/s). Detonation pressure (GPa). Chemical energy of detonation (cal/g). Thermal decomposition
f
g
h
i
j
temperature under nitrogen gas (DSCꢀTGA, 10°C/min). kMelting point (°C)
Table 2. Energetic properties of salts of 1-(1H-1,2,4-triazol-3-yl)-1H-tetrazole (9), 5-(1H-tetrazol-1-yl)-1H-1,2,4-triazol-3-amine (10), 1-(3-azido-1H-1,2,4-triazol-5-yl)-
1H-tetrazole (11), and 3-azido-1H-1,2,4-triazol-5-amine (12) salts.
e
f
g
l
Compd.
9a
NCa (%)
71.4
OBb
HOFcc
567.2
619.5
946.9
796.4
753.8
567.2
619.5
HOFad
349.9
349.9
349.9
349.9
349.9
368.1
368.1
UPot
522
503
508
508
497
510
493
HL
HOFsalt
390
ρh
Di
Pj
Qk
Tdec
Mpm
177
143
ꢀ98.0
ꢀ81.1
ꢀ97.7
ꢀ97.7
ꢀ94.9
ꢀ94.8
ꢀ79.3
527
508
513
513
502
515
498
1.55
1.58
1.59
1.59
1.59
1.55
1.58
6.07
6.76
6.66
6.38
6.32
6.15
6.79
14.86
18.70
18.24
16.72
16.37
15.26
18.83
696
907
1019
856
792
706
901
197
186
187
191
194
200
195
9b
67.8
462
9c
69.7
784
9d
69.7
634
174
141
9e
71.1
601
10a
10b
73.0
420
69.4
490
4
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10d
71.2
72.5
75.8
76.1
75.0
ꢀ94.9
ꢀ92.4
ꢀ78.0
ꢀ87.0
ꢀ85.7
796.4
753.8
753.8
567.2
753.8
368.1
368.1
610.7
296.6
296.6
497
488
481
533
506
502
493
486
538
511
662
629
878
326
539
1.59
1.58
1.67
1.56
1.60
6.43
6.37
6.86
6.20
6.46
16.99
16.62
19.94
15.55
17.18
854
792
894
659
768
190
200
203
167
172
10e
11e
12a
12e
120
aNitrogen Content (%). bOxygen balance (%). cHeat of formation of cation (kJ/mol). dHeat of formation of anion (kJ/mol). eLattice potential energy
(kJ/mol). fLattice energy (kJ/mol). gHeat of formation of salt (kJ/mol). hDensity (g/cm3). iVelocity of detonation (km/s). jDetonation pressure (GPa).
kChemical energy of detonation (cal/g). lThermal decomposition temperature under nitrogen gas (DSCꢀTGA, 10°C/min). mMelting point (°C).
Computational details
+ HOF (anion, 298 K) ꢀ HL
(4)
5
The isodesmic reactions designed for the prediction of gas
50 The lattice energy can be predicted with reasonable accuracy
by using Jenkins’ equation (5),22
18
phase HOF (HOFGas
)
and selective reactions are shown in
Scheme 6. For estimation of the potential performance of the
energetic material, it is also significant to calculate their solid
phase HOF (HOFSolid) because it is related directly with the
10 detonation characteristics. According to Hess’ law, HOFSolid
can be obtained by,
HL = UPOT + [p(nM/2 – 2) + q(nX/2 – 2)]RT
(5)
55 where nM and nX depend on the nature of the ions Mp+ and Xq
ꢀ
, respectively, and are equal to 3 for monoatomic ions, 5 for
linear polyatomic ions, and 6 for nonlinear polyatomic ions.
The lattice potential energy UPOT (kJ/mol) can be predicted
from equation (6) and (7) as suggested by Jenkins et al.22 using
60 following equations,
HOFSolid = HOFGas ꢀ HOFSub
(1)
where HOFSub is the heat of sublimation and can be evaluated
15 by the Byrd and Rice method19 in the framework of the Politzer
approach,20 using the following empirical relation,
UPOT = γ(ρ/M)1/3 + δ
(6)
(7)
UPOT = 2I[α(V)ꢀ1/3 + β]
HOFSub = β1A2 + β2(vσ2tot) + β3
(2)
65
In above equations, ρ is the density (g/cm3), V is the estimated
volume of ionic material (nm3), M is the chemical formula
mass of the ionic material (g/mol), and the coefficients A, B, γ
(kJ/mol.cm), δ (kJ/mol), α, and β are taken from ref. 22(c).
where A is the area of the isosurface of 0.001 electrons/bohr3
20 electronic density, ν indicates the degree of balance between
the positive and negative surface potentials, σ2tot is a measure of
variability of the electrostatic potential, and β1, β2, and β3 are
determined through a leastꢀsquares with the experimental
HOFSolid of a selected set of known materials.19 Surface area,
25 degree of balance between the positive and negative surface
potentials and variability of the electrostatic potential are
calculated using WFA program.21 Oxygen balance gives
information about amount of oxygen needed for an organic
molecule for its complete oxidation. Complete oxidation
30 means, on decomposition, all the carbons and hydrogens in
particular molecule should be converted to carbondioxide and
water. If a molecule contains oxygen within its structure more
than it required for complete oxidation then the oxygen balance
would be positive. OB (%) for an explosive containing the
35 general formula CaHbNcOd with molecular mass M can be
calculated as:
ꢀ
ꢁ
HOF
Cation+ Anionꢀ (Solid)
C(s) + H (g) + N (g) + O (g)
m
n
o
p
2
2
2
ꢁ
HL
ꢀ
ꢁ
HOFanion
Cation+ (gas) + Anionꢀ (gas)
ꢁ
ꢀ
HOFcation
70
Figure 1. BornꢀHaber cycle for the formation of energetic salts (ꢀHL:
lattice enthalpy of ionic salts, ꢀHOFcation and ꢀHOFanion: heat of
formation of cation and anion, respectively).
75
The empirical KamletꢀJacobs17 equations (8) and (9) were
employed to estimate the values of
D and P for the high energy
materials containing C, H, O and N as following equations:
= 1.01(NM0.5Q0.5 0.5
= 1.55ρo 2 NM0.5Q0.5
)
(1 + 1.30ρo)
(8)
(9)
(d ꢀ 2a ꢀ b/2) x1600
D
P
(3)
OB (%) =
80
M
The lattice potential energies and lattice energies were
40 predicted by using Jenkins approach.22 Based on the Born–
Haber cycle shown in Figure 1, the HOF of an ionic compound
can be simplified by subtracting the lattice energy of the salt
(∆HL) from the total heat of formation of salt i.e. sum of the
heats of formation of the cation and anion as shown in equation
45 (4).
where in above equations
detonation pressure (GPa), N is moles of gaseous detonation
85 products per gram of explosives, M is average molecular
weights of gaseous products, is chemical energy of
detonation (cal/g) defined as the difference of the HOFs
between products and reactants, and ρo is the density of
explosive (g/cm3).
D is detonation velocity (km/s), P is
Q
HOF (salt, 298 K) = HOF (cation, 298 K)
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mixture was refluxed for 6 hrs with stirring. The reaction
60 mixture was cooled to room temperature and added
hydrochloric acid (10mL, 1M). The reaction mixture was
extracted with ethyl acetate. The crude product was purified by
column chromatography over silica gel with nꢀhexane/EtOAc
and dried over sodium sulfate. The solvent was removed under
65 reduced pressure and the product was isolated with satisfactory
purity as orange solid (0.225 g, 51.3 %). DSCꢀTGA (10 °C
min–1): 265 °C (dec). IR (KBr): 3136, 2934, 2241, 2150, 1651,
1523, 1437, 1388, 1344, 1307, 1251, 1197, 667, 642, 505 cmꢀ1.
Experimental section
Caution! We have synthesized all compounds in millimolar
amounts and have experienced no difficulties with temperature.
However, appropriate safety precautions should be taken,
especially when these compounds are prepared on a large scale.
The use of appropriate safety precautions (safety shields, face
shields, leather gloves, protective clothing, such as heavy
leather welding suits and ear plugs) is mandatory. Ignoring
safety precautions can lead to accident or serious injury.
10 Material and instruments: The reagents were available
commercially and were used as purchased without further
purification. Reactions were monitored by TLC analysis, by
using precoated silica gel TLC plates obtained from Merck. 1H
and 13C NMR spectroscopic data were recorded on a Bruker
15 Avance 400 MHz FT NMR spectrometer with
tetramethylsilane (TMS) as an internal standard and
[D6]DMSO as the solvent. Mass analysis was performed on a
LCꢀMS spectrometer. Melting points and decomposition
temperatures were determined by DSCꢀTGA using TA
20 instruments SDT Q 600 instrument. The IR spectra were
recorded on a Perkin–Elmer IR spectrometer by using KBr
pellets. The HRMS were recorded on a Bruker Maxis
instrument. Elemental analyses were performed on a flash EA
1112 full automatic trace element analyzer.
25 1H-Tetrazol-5-amine (1): A mixture of cyanamide (0.200 g,
4.76 mmol), sodium azide (0.309 g, 4.76 mmol) and iodine
(0.06 g) suspended in DMF (10 mL), was refluxed for 6 hrs
with stirring. The reaction mixture was cooled to room
temperature and hydrochloric acid (10mL, 1M) was added. The
30 reaction mixture was extracted with ethyl acetate and dried
over sodium sulfate. The solvent was removed under reduced
pressure and the products were isolated with satisfactory purity
as a white solid (0.280 g, 69.2 %). IR (KBr): 3410, 3217, 2934,
2812, 2501, 2199, 1658, 1568, 1516, 1415, 1253, 1105, 1051,
35 1012, 923, 653, 621 cmꢀ1. 1H NMR (400 MHz, DMSO): δ
(ppm) 4.97 (s, 4H). 13C NMR (100 MHz, DMSO): δ (ppm)
164. LCꢀMS (ES, m/z): 86 [M+H]+.
5
1H NMR (400 MHz, DMSO):
δ
(ppm) 7.21 (s, 2H). 13C NMR
70 (100 MHz, DMSO): δ (ppm) 162.7, 153.8, 142.3. HRMS (ESI)
for C3H3N7 (M+H): calcd 219.9018, found 220.1048. LCꢀMS
(ES, m/z): 220 [M+H]+. C, H, N analysis (%): C5H5N11 (219),
Calculated result: C, 27.40; H, 2.30; N, 70.30; Found: C, 27.51;
H, 2.36; N, 70.21.
75 2-(1H-Tetrazol-1-yl)-1H-imidazole-4,5-dicarbonitrile (6): 2ꢀ
Aminoꢀ1Hꢀimidazoleꢀ4,5ꢀdicarbonitrile (1 g, 7.5 mmol) and
sodium azide (0.733 g, 11.27 mmol) was suspended in triethyl
orthoformate (2 mL) and glacial acetic acid (20 mL) was
added, and the mixture was refluxed for 8 hrs. The slurry was
80 concentrated in vacuum, and residue was partitioned between
ethyl acetate (250 mL) and 3N HCl (50 mL). The organic phase
was dried over Na2SO4, filtered and concentrated under
vacuum to get the compound as a white solid (0.900 g, 64.5 %).
DSCꢀTGA (10 °C min–1): 238 °C (dec). IR (KBr): 3439, 3350,
85 2922, 2852, 2233, 1693, 1651, 1591, 1531, 1469, 1309, 1255,
1143, 1103, 1028, 866, 798, 715, 652 cmꢀ1. 1H NMR (400
MHz, DMSO): δ (ppm) 9.89 (s, 1H). 13C NMR (100 MHz,
DMSO):
δ (ppm) 153.8, 142.7, 115.3, 112.5. HRMS (ESI) for
C6H2N8 (M+H): calcd 186.0402, found 187.0476. LCꢀMS (ES,
90 m/z): 186 [MꢀH]ꢀ. C, H, N analysis (%): C6H2N8 (187),
Calculated result: C, 38.72; H, 1.08; N, 60.20; Found: C, 38.65;
H, 1.16; N, 60.36.
5,5'-(2-(1H-Tetrazol-1-yl)-1H-imidazole-4,5-diyl)bis(1H-
tetrazole) (7): Sodium azide (0.172 g, 2.65 mmol) and iodine
95 (0.120 g, 47.2 mmol) were added to a solution of 2ꢀ(1
Hꢀ
tetrazolꢀ1ꢀyl)ꢀ1 ꢀimidazoleꢀ4,5ꢀdicarbonitrile (0.215 g, 1.1
H
2-Azido-1H-imidazole-4,5-dicarbonitrile (4): 2ꢀAminoꢀ1Hꢀ
mmol) in DMF (10 mL). The reaction mixture was refluxed for
6 hrs with stirring. The reaction mixture was cooled to room
temperature and added hydrochloric acid (20 mL, 1M). The
100 reaction mixture was extracted with ethyl acetate.The crude
product was purified by column chromatography over silica gel
with nꢀhexane/EtOAc and dried over sodium sulfate. The
solvent was removed under reduced pressure and the product
was isolated with satisfactory purity as a white solid (0.060 g,
105 15%). DSCꢀTGA (10 °C min–1): 179 °C (dec). IR (KBr): 3324,
3136, 2934, 2241, 2150, 1651, 1523, 1437, 1388, 1344, 1307,
imidazoleꢀ4,5ꢀdicarbonitrile (1.33 g, 10 mmol) dissolved in
40 hydrochloric acid (7.5 mL) in a 100 mL roundꢀbottom flask
was cooled to ~0°C in an ice bath. To this stirred mixture,
NaNO2 (1 g, 40 mmol) in 3 mL of water was added and stirred
vigorously at room temperature. After this, excess amount of
NaNO2 was added slowly to the mixture (up to disappearing
45 starting material spot in TLC). The crude product was extracted
with ethyl acetate and the solvent was evaporated under
vacuum to give the yellow solid (0.110 g, 69.1 %). DSCꢀTGA
(10 °C min–1): 114 °C (m.p.), 178 °C (dec). IR (KBr): 3308,
2924, 2854, 2446, 2361, 2239, 2156, 1712, 1562, 1525, 1482,
50 1442, 1410, 1315, 1228, 1140, 719, 652 cmꢀ1. 13C NMR (100
MHz, DMSO): δ (ppm) 150.2, 117.2, 115.2. LCꢀMS (ES, m/z):
160 [M+H]+. C, H, N analysis (%): C5HN7 (159), Calculated
result: C, 37.74; H, 0.63; N, 61.62; Found: C, 37.62; H, 0.71;
N, 61.52.
1
1251, 1197, 667, 642, 505 cmꢀ1. H NMR (400 MHz, DMSO):
δ (ppm) 9.89 (s, 1H). 13C NMR (100 MHz, DMSO): δ (ppm)
160.5, 153.9, 146.3, 142.1. HRMS (ESI) for C6H4N14 (M+H):
110 calcd 273.0743, found 273.0707. LCꢀMS (ES, m/z): 273
[M+H]+. C, H, N analysis (%): C6H4N14 (272), Calculated
result: C, 26.48; H, 1.48; N, 72.04; Found: C, 26.35; H, 1.41;
N, 72.15.
55 4,5-Di(1H-tetrazol-5-yl)-1H-imidazol-2-amine (5): Sodium
azide (0.395 g, 6 mmol) and iodine (0.06 g, 0.47 mmol) was
2-Amino-5-cyano-1H-imidazole-4-carboxamide
(8)
:
2ꢀ
115 Aminoꢀ1
Hꢀimidazoleꢀ4,5ꢀdicarbonitrile (0.300 g, 2.25 mmol)
added to
a
solution of
2ꢀaminoꢀ1Hꢀimidazoleꢀ4,5ꢀ
was added to the mixture of phenol (0.848 g, 9.02 mmol) and
dicarbonitrile (0.266 g, 2 mmol) in DMF (10 mL). The reaction
6
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33% HBr/AcOH. The reaction mixture was stirred for 18 hrs at
TGA (10 °C min–1): 143 °C (m.p.), 186 °C (dec). IR (KBr):
60 3368, 3306, 3140, 3037, 2985, 2913, 1635, 1552, 1479, 1469,
1381, 1319, 1267, 1200, 1122, 1091, 1019, 982 cmꢀ1. 1H NMR
(400 MHz, DMSO): δ (ppm) 9.45 (s, 1H), 8.19 (s, 1H) 6.57 (s,
2H), 5.74 (s, 5H). 13C NMR (100 MHz, DMSO): δ (ppm)
167.1, 157.6, 151.2, 151.1, 148.3. DEPT (100 MHz, DMSO): δ
65 (ppm) 151.0, 148.3. LCꢀMS (ES, m/z): 228 [M+H]+. C, H, N
analysis (%): C4H9N11O (227), Calculated result: C, 21.15; H,
3.99; N, 67.82; O, 7.04; Found: C, 21.06; H, 3.91; N, 67.62.
4-Amino-4H-1,2,4-triazol-1-ium 3-(1H-tetrazol-1-yl)-1,2,4-
triazol-1-ide (9c): White solid (0.150 g, 93 %). DSCꢀTGA (10
70 °C min–1): 187 °C (dec). IR (KBr): 3130, 3027, 2908, 1878,
1831, 1626, 1547, 1484, 1459, 1391, 1272, 1189, 1122, 1096,
1024, 982, 832, 729 cmꢀ1. 1H NMR (400 MHz, DMSO): δ
(ppm) 10.12 (s, 1H), 8.88 (s, 1H) 8.41 (s, 2H), 6.23 (s, 3H). 13C
NMR (100 MHz, DMSO): δ (ppm) 152.9, 146.2, 144.6, 143.5.
75 DEPT (100 MHz, DMSO): δ (ppm) 146.2, 144.6, 143.5.
HRMS (ESI) for C5H7N11 (M+Na): calcd 221.0886, found
244.0763. LCꢀMS (ES, m/z): 222 [M+H]+. C, H, N analysis
(%): C5H7N11 (221), Calculated result: C, 27.15; H, 3.19; N,
69.66; Found: C, 27.06; H, 3.25; N, 69.51.
room temperature. Then, the reaction mixture was poured into
diethyl ether (20mL) and the precipitate was filtered. The
collected solid was dissolved in minimal amount of refluxed
methanol (5mL) and cooled to room temperature followed by
drop wise addition of diethyl ether, the precipitate filtered and
dried. White solid (0.250 g, 73.5 %). DSCꢀTGA (10 °C min–1):
180 °C (m.p.). IR (KBr): 3447, 3406, 3348, 3096, 2878, 2737,
2233, 1705, 1670, 1616, 1595, 1577, 1508, 1452, 1396, 1359,
5
10 1251, 1213, 1070, 1043, 783, 702, 657, 601, 545, 486, 455 cmꢀ
1
1. H NMR (400 MHz, DMSO): δ (ppm) 7.93 (s, 2H), 7.69 (s,
2H). 13C NMR (100 MHz, DMSO): δ (ppm) 158.36, 149.32,
133.32, 111.94, 102.55. HRMS (ESI) for C5H5N5O (M+H):
calcd 151.0494, found 152.0571. LCꢀMS (ES, m/z): 152
15 [M+H]+. C, H, N analysis (%): C5H5N5O (151), Calculated
result: C, 39.74; H, 3.33; N, 46.34; O, 10.59; Found: C, 39.62;
H, 3.38; N, 46.23.
1-(1H-1,2,4-Triazol-3-yl)-1H-tetrazole (9):
1Hꢀ1,2,4ꢀtriazolꢀ
3ꢀamine (1 g, 11.90 mmol) and sodium azide (0.773 g, 23.80
20 mmol) was suspended in triethyl orthoformate (3 mL) and
glacial acetic acid (20 mL) was added, and the mixture was
refluxed for 8 hrs. The slurry was concentrated in vacuum and
residue was partitioned between ethyl acetate (200 mL) and 3N
HCl (100 mL). The organic phase was dried over Na2SO4,
25 filtered and concentrated under vacuum to get the target
compound as white solid (1.5 g, 91.9 %). DSCꢀTGA (10 °C
min–1): 228 °C (dec). IR (KBr): 3130, 3032, 2985, 2908, 1547,
1479, 1381, 1324, 1277, 1200, 1179, 1122, 1091, 1014, 977
cmꢀ1. 1H NMR (400 MHz, DMSO): δ (ppm) 10.12 (s, 1H), 8.88
30 (s, 1H). 13C NMR (100 MHz, DMSO): δ (ppm) 152.9, 146.2,
143.5. DEPT (100 MHz, DMSO): δ (ppm) 146.2, 143.8.
HRMS (ESI) for C3H3N7 (M+Na): calcd 137.0450, found
160.0345. LCꢀMS (ES, m/z): 138 [M+H]+. C, H, N analysis
(%): C3H3N7 (137), Calculated result: C, 26.28; H, 2.21; N,
35 71.51; Found: C, 26.58; H, 1.42; N, 72.21.
80 3-Amino-1H-1,2,4-triazol-4-ium 3-(1H-tetrazol-1-yl)-1,2,4-
triazol-1-ide (9d): White solid (0.160 g, 99.2 %). DSCꢀTGA
(10 °C min–1): 174 °C (m.p.), 191 °C (dec). IR (KBr): 3399,
3311, 3125, 3037, 2985, 2918, 1624, 1547, 1479, 1417, 1319,
1
1283, 1189, 1127, 1091, 1055, 1008, 982 cmꢀ1. H NMR (400
85 MHz, DMSO): δ (ppm) 10.13 (s, 1H), 8.88 (s, 2H) 5.50 (s, 2H).
13C NMR (100 MHz, DMSO): δ (ppm) 158.8, 152.9, 146.3,
143.5. DEPT (100 MHz, DMSO): δ (ppm) 146.3, 143.5. LCꢀ
MS (ES, m/z): 222 [M+H]+. C, H, N analysis (%): C5H7N11
(221), Calculated result: C, 27.15; H, 3.19; N, 69.66; Found: C,
90 27.06; H, 3.24; N, 69.52.
3,5-Diamino-1H-1,2,4-triazol-4-ium
3-(1H-tetrazol-1-yl)-
1,2,4-triazol-1-ide (9e): White solid (0.155 g, 90 %). DSCꢀ
TGA (10 °C min–1): 141 °C (m.p.), 194 °C (dec). IR (KBr):
3410, 3327, 3130, 3037, 2985, 2918, 2721, 1883, 1831, 1650,
95 1541, 1474, 1391, 1283, 1117, 1086, 1034, 972 cmꢀ1. 1H NMR
(400 MHz, DMSO): δ (ppm) 10.13 (s, 1H), 8.88 (s, 1H). 13C
NMR (100 MHz, DMSO): δ (ppm) 158.3, 152.9, 148.1, 146.2,
143.5. DEPT (100 MHz, DMSO): δ (ppm) 146.2, 143.5. LCꢀ
MS (ES, m/z): 237 [M+H]+. C, H, N analysis (%): C5H8N12
100 (236), Calculated result: C, 25.43; H, 3.41; N, 71.16; Found: C,
25.51; H, 3.36; N, 71.32.
General Procedure for the Preparation of Salts of 9:
solution of guanidine (0.089 g, 0.729 mmol), carbohydrazide
(0.065 g, 0.7293 mmol), 4 ꢀ1,2,4ꢀtriazolꢀ4ꢀamine (0.061 g,
A
H
0.729 mmol), 3ꢀaminoꢀ1,2,4ꢀtriazole (0.060 g, 0.729 mmol),
40 3,5ꢀdiaminoꢀ1,2,4ꢀtriazole (0.072 g, 0.729 mmol), in methanol
(6 mL) was slowly added to a solution of
9 (0.100g, 0.729
mmol) in methanol (8 mL) at 25 °C with stirring. After stirring
for 6 h at room temperature, the solvent was removed in vacuo
to leave the desired product.
5-(1H-Tetrazol-1-yl)-1H-1,2,4-triazol-3-amine (10):
1Hꢀ
45 Diaminomethaniminium 3-(1H-tetrazol-1-yl)-1,2,4-triazol-
1-ide (9a): White solid (0.135 g, 94.4 %). DSCꢀTGA (10 °C
min–1): 177 °C (m.p.), 197 °C (dec). IR (KBr): 3410, 3192,
3146, 3032, 2980, 2908, 1676, 1578, 1541, 1479, 1386, 1272,
1189, 1112, 1091, 972, 962, 827, 539 cmꢀ1. 1H NMR (400
50 MHz, DMSO): δ (ppm) 8.05 (s, 1H), 6.82 (s, 1H) 4.91 (s, 6H).
13C NMR (100 MHz, DMSO): δ (ppm) 158.3, 152.9, 146.2,
143.5. DEPT (100 MHz, DMSO): δ (ppm) 146.2, 143.5.
HRMS (ESI) for C4H8N10 (M+H): calcd 196.0933, found
197.1009. LCꢀMS (ES, m/z): 197 [M+H]+. C, H, N analysis
55 (%): C4H8N10 (196), Calculated result: C, 24.49; H, 4.11; N,
71.40; Found: C, 24.56; H, 4.06; N, 71.52.
1,2,4ꢀtriazoleꢀ3,5ꢀdiamine (1 g, 10.1 mmol) and sodium azide
(1.969 g, 30.3 mmol) was suspended in triethyl orthoformate (8
105 mL) and glacial acetic acid (35 mL) was added, the mixture
was reflexed for 8 hrs. The slurry was concentrated in vacuum
and residue was partitioned between ethyl acetate (500 mL)
and 3N HCl (100 mL). The organic phase was dried over
Na2SO4, filtered and concentrated under vacuum to get the
110 compound as white solid (0.800 g, 52.1 %). DSCꢀTGA (10 °C
min–1): 238 °C (dec). IR (KBr): 3491, 3393, 3119, 2922, 1697,
1651, 1562, 1531, 1444, 1325, 1255, 1192, 1163, 1101, 1072,
1039, 978, 798, 733, 653, 526 cmꢀ1. 1H NMR (400 MHz,
DMSO): δ (ppm) 12.64 (s, 1H), 9.92 (s, 1H) 6.65 (s, 2H). 13C
115 NMR (100 MHz, DMSO): δ (ppm) 157.9, 150.4, 143.0. DEPT
(100 MHz, DMSO): δ (ppm) 143.0. HRMS (ESI) for C3H4N8
(Hydrazinylcarbonyl) hydrazinium 3-(1H-tetrazol-1-yl)-
1,2,4-triazol-1-ide (9b): White solid (0.150 g, 90.5 %). DSCꢀ
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(M+H): calcd 152.0559, found 153.0361. LCꢀMS (ES, m/z):
153 [M+H]+. C, H, N analysis (%): C3H4N8 (152), Calculated
result: C, 23.69; H, 2.65; N, 73.66; Found: C, 23.76; H, 2.58;
N, 73.45.
3ꢀamine (0.200 g, 1.31 mmol) was dissolved in CH3CN (4 mL)
60 and cooled to 0°C in an ice bath. To this stirred mixture tꢀ
BuONO (0.203 g, 0.2347 ꢂL, 2.27 mmol) was added followed
by TMSN3 (0.1818 g, 0.2075 ꢂL, 1.8 mmol) dropwise. The
resulting solution was stirred at room temperature for 1 h. The
reaction mixture was concentrated under vacuum and the crude
65 product was purified by silica gel chromatography (hexane) to
give the target product as a orange solid (0.200 g, 85.3 %).
DSCꢀTGA (10 °C min–1): 223 °C (dec). IR (KBr): 3264, 3117,
2155, 1699, 1633, 1532, 1374, 1319, 1253, 1177, 1086, 974,
878, 726 cmꢀ1. 1H NMR (400 MHz, DMSO): δ (ppm) 10.14 (s,
70 1H). 13C NMR (100 MHz, DMSO): δ (ppm) 146.2, 143.6,
134.4. HRMS (ESI) for C3H2N10 (M+H): calcd 178.0464,
found 179.0547. LCꢀMS (ES, m/z): 179 [M+H]+. C, H, N
analysis (%): C3H2N10 (178), Calculated result: C, 20.23; H,
1.13; N, 78.64; Found: C, 20.32; H, 1.18; N, 78.54.
5
General Procedure for the Preparation of Salts of 10: A
solution of guanidine (0.080g, 0.6578 mmol), carbohydrazide
(0.059g, 0.6578 mmol), 3ꢀaminoꢀ1,2,4ꢀtriazole (0.066g, 0.6578
mmol), 3,5ꢀdiaminoꢀ1,2,4ꢀtriazole (0.065g, 0.6578 mmol), in
methanol (10 mL) was slowly added to a solution of 10
10 (0.100g, 0.6535 mmol) in methanol (8 mL) at 25 °C with
stirring. After stirring for 6 h at room temperature, the solvent
was removed in vacuo to leave the desired product.
Diaminomethaniminium
3-amino-5-(1H-tetrazol-1-yl)-
1,2,4-triazol-1-ide (10a): White solid (0.130 g, 93.6 %). DSCꢀ
15 TGA (10 °C min–1): 200 °C (dec 1), 268 °C (dec 2). IR (KBr):
3112, 2980, 1961, 1605, 1479, 1419, 1200, 1063, 953 cmꢀ1. 1H
NMR (400 MHz, DMSO): δ (ppm) 9.91 (s, 1H), 6.94 (s, 6H)
6.64 (s, 2H). 13C NMR (100 MHz, DMSO): δ (ppm) 158.3,
157.9, 150.4, 143.0. HRMS (ESI) for C4H9N11 (M+H): calcd
20 211.1042, found 212.1118. LCꢀMS (ES, m/z): 212 [M+H]+. C,
H, N analysis (%): C4H9N11 (211), Calculated result: C, 22.75;
H, 4.30; N, 72.96; Found: C, 22.61; H, 4.41; N, 72.85.
75 General Procedure for the Preparation of Salts of 11:
A
solution of 3,5ꢀdiaminoꢀ1,2,4ꢀtriazole (0.112 g, 1.13 mmol), in
methanol (10 mL) was slowly added to a solution of 11 (0.200
g, 1.13 mmol) in methanol (8 mL) at 25 °C with stirring. After
stirring for 6 h at room temperature, the solvent was removed
80 in vacuo to leave the desired product.
(Hydrazinylcarbonyl)hydrazonium 3-mino-5-(1H-tetrazol-
1-yl)-1,2,4-triazol-1-ide (10b): Yellow solid (0.150 g, 94.2
25 %). DSCꢀTGA (10 °C min–1): 195 °C (dec). IR (KBr): 3358,
3325, 3298, 3199, 1659, 1517, 1445, 1319, 1265, 1204, 1100,
3,5-Diamino-1H-1,2,4-triazol-4-ium 3-azido-5-(1H-tetrazol-
1-yl)-1,2,4-triazol-1-ide (11e): Orange solid (0.280 g, 88.9
%). DSCꢀTGA (10 °C min–1): 203 °C (dec). IR (KBr): 3399,
3311, 3104, 2136, 1707, 1655, 1629, 1562, 1479, 1422, 1262,
1
1
1051, 980, 919 cmꢀ1. H NMR (400 MHz, DMSO): δ (ppm)
85 1086, 1055, 977 cmꢀ1. H NMR (400 MHz, DMSO): δ (ppm)
9.94 (s, 1H), 7.25 (s, 5H) 6.68 (s, 2H). 13C NMR (100 MHz,
DMSO): δ (ppm) 162.2, 157.9, 150.4, 143.0. HRMS (ESI) for
30 C4H10N12O (M+H): calcd 242.1101, found 243.1173. LCꢀMS
(ES, m/z): 243 [M+H]+. C, H, N analysis (%): C4H10N12O
(242), Calculated result: C, 19.84; H, 4.16; N, 69.40; O, 6.61;
Found: C, 19.69; H, 4.23; N, 69.28.
10.11 (s, 1H). 13C NMR (100 MHz, DMSO): δ (ppm) 156.9,
153.1, 150.3, 143.2. DEPT (100 MHz, DMSO): δ (ppm) 143.2.
LCꢀMS (ES, m/z): 278 [M+H]+. C, H, N analysis (%): C5H7N15
(277), Calculated result C, 21.66; H, 2.55; N, 75.79; Found: C,
90 21.52; H, 2.58; N, 75.63.
3-Azido-1H-1,2,4-triazol-5-amine (12):
1Hꢀ1,2,4ꢀTriazoleꢀ
3-Amino-1H-1,2,4-triazol-4-ium 3-amino-5-(1H-tetrazol-1-
35 yl)-1,2,4-triazol-1-ide (10d): White solid (0.150 g, 96.6 %).
DSCꢀTGA (10 °C min–1): 190 °C (dec). IR (KBr): 3472, 3360,
3126, 1651, 1558, 1531, 1448, 1421, 1377, 1325, 1257, 1194,
1072, 979, 868, 731, 650, 621 cmꢀ1. 1H NMR (400 MHz,
DMSO): δ (ppm) 9.90 (s, 1H), 8.42 (s, 4H) 6.67 (s, 2H). 13C
40 NMR (100 MHz, DMSO): δ (ppm) 157.91, 150.45, 144.62,
143.02. DEPT (100 MHz, DMSO): δ (ppm) 144.61, 143.02.
LCꢀMS (ES, m/z): 237 [M+H]+. C, H, N analysis (%): C5H8N12
(236), Calculated result: C, 25.43; H, 3.41; N, 71.16; Found: C,
25.15; H, 3.76; N, 70.69.
3,5ꢀdiamine (1.5 g, 12 mmol) was dissolved in sulfuric acid (15
mL of 20% ) at room temp. The clear solution obtained after
dissolution was cooled to ~0ꢀ5 °C and a solution of sodium
95 nitrite (0.166 g, 24 mmol) in water (20 mL) was added slowly
to this solution over a period of 2 h keeping the temperature
below 10 °C. A small amount of urea was added to the bright
yellow reaction mixture to expel the oxides of nitrogen. A
solution of sodium azide (0.156 g, 24 mmol) in water (20 mL)
100 was added in small portions while keeping the temperature
below 10 °C. The resulting solution was stirred for 1 h at 20 °C
and afterwards slowly heated to 40 °C. The solution was
neutralized using sodium hydrogen carbonate and the product
was extracted using ethyl acetate. The combined extracts were
105 dried over magnesium sulfate. The crude offꢀwhite product,
isolated by removing the solvent under vacuum, was
recrystallized from dry toluene to obtain as a white solid (1.4 g,
93.3 %). DSCꢀTGA (10 °C min–1): 153 °C (m.p.), 173 °C
(dec). IR (KBr): 3470, 3430, 3470, 3336, 3128, 2142 (N3),
110 1660, 1435, 1221, 1019, 816 cmꢀ1. 1H NMR (400 MHz,
DMSO): δ (ppm) 11.84 (s, 1H), 6.27 (s, 2H). 13C NMR (100
MHz, DMSO): δ (ppm) 157.4, 154. HRMS (ESI) for C2H3N7
(M+H): calcd 125.0450, found 148.0348. LCꢀMS (ES, m/z):
126 [M+H]+.C, H, N analysis (%): C2H3N7 (125), Calculated
115 result: C, 19.20; H, 2.42; N, 78.38; Found: C, 19.12; H, 2.46;
N, 78.21.
45 3,5-Diamino-1H-1,2,4-triazol-4-ium
3-amino-5-(1H-
tetrazol-1-yl)-1,2,4-triazol-1-ide (10e): White solid (0.160 g,
96.8 %). DSCꢀTGA (10 °C min–1): 120 °C (m.p.), 200 °C
(dec). IR (KBr): 3395, 3304, 3112, 1648, 1562, 1516, 1486,
1410, 1263, 1091, 1055, 974 cmꢀ1. 1H NMR (400 MHz,
50 DMSO): δ (ppm) 9.91 (s, 1H), 6.67 (s, 2H). 13C NMR (100
MHz, DMSO): δ (ppm) 157.9, 150.4, 143.1, 143.0. DEPT (100
MHz, DMSO): δ (ppm) 143.0. HRMS (ESI) for C5H9N13
(M+H): calcd 251.1104, found 252.1177. LCꢀMS (ES, m/z):
249 [M+H]+. C, H, N analysis (%): C5H9N13 (251), Calculated
55 result: C, 23.91; H, 3.61; N, 72.48; Found: C, 24.12; H, 3.21;
N, 72.65.
1-(3-Azido-1H-1,2,4-triazol-5-yl)-1H-tetrazole (11): In 25
mL roundꢀbottom flask, 5ꢀ(1Hꢀtetrazolꢀ1ꢀyl)ꢀ1Hꢀ1,2,4ꢀtriazolꢀ
8
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DOI: 10.1039/C3RA47227B
General Procedure for the Preparation of Salts of 12:
A
Chemistry and CMSD, University of Hyderabad for providing
experimental and computational facilities.
solution of guanidine (0.047 g, 0.8 mmol), 3,5ꢀdiaminoꢀ1,2,4ꢀ
triazole (0.079g, 0.8 mmol), in methanol (6 mL) was slowly
added to a solution of 12 (0.100 g, 0.8 mmol) in methanol (8
mL) at 25 °C with stirring. After stirring for 6 h at room
temperature, the solvent was removed in vacuo to leave the
desired product.
Notes and references
5
60 a Advanced Centre of Research in High Energy Materials (ACRHEM),
University of Hyderabad, Hyderabadꢀ500 046 (India)
b Department of Chemistry, National Institute of Technology,
Kurukshetraꢀ136119, Haryana (India).
Diaminomethaniminium 5-amino-3-azido-1,2,4-triazol-1-
ide (12a): Orange solid (0.132 g, 89.6 %). DSCꢀTGA (10 °C
c School of Chemistry, University of Hyderabad, Hyderabadꢀ500 046
65 (India). Eꢀmail: kmsc@uohyd.ernet.in
10 min–1): 167 °C (dec). IR (KBr): 3408, 3200, 2147 (N3), 1665,
1605, 1578, 1545, 1358, 1227, 1008 cmꢀ1. 1H NMR (400 MHz,
DMSO): δ (ppm) 6.93 (s, 6H), 6.28 (s, 2H). 13C NMR (100
MHz, DMSO): δ (ppm) 158.3, 157.4, 154.4. HRMS (ESI) for
C3H8N10 (M+H): calcd 184.0933, found 185.1009. LCꢀMS
15 (ES, m/z): 185 [M+H]+. C, H, N analysis (%): C3H8N10 (184),
Calculated result: C, 19.57; H, 4.38; N, 76.06; Found: C, 19.46;
H, 4.31; N, 76.21.
† Electronic Supplementary Information (ESI) available: [details of
any supplementary information available should be included here]. See
DOI: 10.1039/b000000x/
1
T. M. Klapötke, A. Preimesser, J. Stierstorfer, Z. Anorg. Allg.
Chem., 2012, 638, 1278; T. M. Klapötke, J. Stierstorfer, Dalton
Trans., 2009, 643; T. M. Klapötke, C. M. Sabate, J. Stierstorfer,
New J. Chem., 2009, 33, 136; V. Thottempudi, J. M. Shreeve, J.
Am. Chem. Soc., 2011, 133, 19982; V. Thottempudi, H. Gao, J. M.
Shreeve, J. Am. Chem. Soc., 2011, 133, 6464; R. Wang, Y. Guo, Z.
Zeng, B. Twamley. J. M. Shreeve, Chem. Eur. J., 2009, 15, 2625;
T. M. Klapötke, S. M. Sproll, Eur. J. Org. Chem., 2010, 1169; K.
Muralidharan, B. A. Omotowa, B. Twamley, C. Piekarski, J. M.
Shreeve, Chem. Commun., 2005, 5193.
70
75
3,5-Diamino-1H-1,2,4-triazol-4-ium 5-amino-3-azido-1,2,4-
triazol-1-ide (12e): Orange solid (0.170 g, 94.8 %). DSCꢀ
20 TGA (10 °C min–1): 172 °C (dec). IR (KBr): 3408, 3315, 3117,
2147(N3), 1621, 1561, 1490, 1419, 1347, 1221, 1052 cmꢀ1. H
1
2
3
H. Gao, J. M. Shreeve, Chem. Rev., 2011, 111, 7377.
NMR (400 MHz, DMSO): δ (ppm) 6.28 (s, 2H), 5.14 (s, 4H).
13C NMR (100 MHz, DMSO): δ (ppm) 158.8, 157.4, 154.4,
153.2. HRMS (ESI) for C4H8N12 (M+H): calcd 224.0995,
25 found 225.1073. LCꢀMS (ES, m/z): 225 [M+H]+. C, H, N
analysis (%): C4H8N12 (224), Calculated result: C, 21.43; H,
3.60; N, 74.97; Found: C, 21.37; H, 3.65; N, 74.85.
80
(a) H. Xue, B. Twamley, J. M. Shreeve, Adv. Mater., 2005, 17,
2142; C. F. Ye, J. C. Xiao, B. Twamley, J. M. Shreeve, Chem.
Commun., 2005, 2750; C. M. Jin, C. F. Ye, C. Piekar ski, B.
Twamley, J. M. Shreeve, Eur. J. Inorg. Chem., 2005, 3760; Y.
Guo, H. Gao, B. Twamley, J. M. Shreeve, Adv. Mater., 2007, 19,
2884; R. Wang, H. Gao, C. Ye, B. Twamley, J. M. Shreeve, Inorg.
Chem., 2007, 46, 932; Z. Zeng, H. Gao, B. Twamley, J. M.
Shreeve, J. Mater. Chem., 2007, 17, 3819; H. Xue, H. Gao, B.
Twamley, J. M. Shreeve, Chem. Mater., 2007, 19, 1731; H. Gao,
Y. Huang, C. Ye, B. Twamley, J. M. Shreeve, Chem. Eur. J., 2008,
85
Conclusions
90
14, 5596; D. Srinivas, V. D. Ghule,
Muralidharan, Chem. Eur. J., 2012, 18, 15031.
S. P. Tewari, K.
A family of nitrogenꢀrich compounds and energetic salts were
30 prepared and fully characterized. The densities of the designed
salts fall within the range 1.55 to 1.78 g/cm3, which place most
of them in a class of relatively dense compounds. Using
Kamlet–Jacobs equations, we calculated their detonation
pressures and velocities; these fall in the range 14.7 to 27.2
35 GPa and 6.0–7.85 km/s, respectively. Salts of 3ꢀnitroꢀ1,2,4ꢀ
triazole cation show high positive heat of formation, density
and performance. All salts decompose between 146 to 238 °C
and own good thermal stability. All the designed compounds
possess negative oxygen balance, thus affects the performance
40 of these compounds, which needs external oxygen supplier for
the conversion of explosives into their gaseous reaction
products. We are currently working on the mixture of these
compounds with suitable oxidizer to evaluate their performance
and to expand the scope of these compounds to the construction
45 of nitrogenꢀrich frameworks containing diverse nitrogen
heterocyclic building blocks. More importantly, it is
noteworthy that most of the compounds in this work amenable
to large scale synthesis with high yields, easy to control
reaction conditions, reproducibility and facile purification.
50 Furthermore, based on detonation properties and superior
thermal stabilities, these salts have potential as gas generators
and enthalpy modifiers in energetic materials.
4
5
6
J. Kohler, R. Mayer, Explosivstoffe, WileyꢀVCH: Weinheim, 9th
Ed. 1998.
S. Oga, Jpn. Kokai Tokkyo Koho, 2006, JP2006249061,
A20060921, AN2006:976599.
95
T. M. Klapötke, G. Holl, J. Geith, A. Hammerl, J. J. Weigand,
New Trends in Research of Energetic Materials, in Proceedings of
the Seminar, 7th, Pardubice, Czech Republic, ed. J. Wagenknecht,
Press of the University of Pardubice, Pardubice, 2004, 1, 25.
T. M. Klapötke, J. Stierstorfer, A. U. Wallek, Chem. Mater., 2008,
20, 4519; D. Srinivas, V. D. Ghule, K.Muralidharan, H. Donald B.
Jenkins, Chem. Asian J., 2013, 8, 1023; T. M. Klapötke, P. Mayer,
J. J. Stierstorfer, J. J. Weigand, J. Mater. Chem., 2008, 18, 5248.
H. Delalu, K. Karaghiosoff, T. M. Klapötke, C. M. Sabate, Cent.
Eur. J. Energ. Mater., 2010, 7, 197; T. Fendt, N. Fischer, T. M.
Klapötke, J. Stierstorfer, Inorg. Chem., 2011, 50, 1447; J.
Stierstorfer, K. R. Tarantik, T. M. Klapötke, Chem. Eur. J., 2009,
15, 5775; N. Fischer, T. M. Klapötke, J. Stierstorfer, C.
Wiedemann, Polyhedron, 2011, 30, 2374; K. F. Warner, R. H.
Granholm, J. Energ. Mater., 2011, 29, 1; M. I. Barmin, S. A.
Gromova,; V. V. Mel’nikov, Russ. J. Appl. Chem., 2001, 74, 1156;
T. M. Klapötke, N. K. Minar, J. Stierstorfer, Polyhedron, 2009, 28,
13; V. Ernst, T. M. Klapötke, J. Stierstorfer, Z. Anorg. Allg. Chem.,
2007, 633, 879; T. M. Klapötke, H. A. Laub, J. Stierstorfer,
Propellants Explos. Pyrotech., 2008, 33, 421; R. Damavarapu, T.
M. Klapötke, J. Stierstorfer, K. R. Tarantik, Propellants Explos.
Pyrotech., 2010, 35, 395; N. Fischer, T. M. Klapötke, J.
Stierstorfer, Z. Anorg. Allg. Chem., 2009, 635, 271; T. Fendt, N.
Fischer, T. M. Klapötke, J. Stierstorfer, Inorg. Chem., 2011, 50,
1447; Y. H. Joo, H. Gao, D. A. Parrish, S. G. Cho, E. M. Goh, J.
M. Shreeve, J. Mater. Chem., 2012, 22, 6123; G. H. Tao, Y. Guo,
Y. H. Joo, B. Twamley, J. M. Shreeve, J. Mater. Chem., 2008, 18,
5524; Y. H. Joo, W. B. Jeong, S. G. Cho, E. M. Goh, Y. G. Lim, S.
S. Moon, Bull. Korean Chem. Soc., 2012, 33, 373; E. F. Rothgery,
100
105
110
115
120
7
8
Acknowledgments
The authors thank the Defence Research and Development
55 Organization (DRDO), India in the form of a grant to
ACRHEM. The authors are also grateful to the School of
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K. O. Knollmueller, US Patent 5424449, 1995; R. A. Batey, D. A.
Powell, Org. Lett., 2000, 2, 3237; A. R. Modarresi Alam, M.
Nasrollahzadeh, Turk. J. Chem., 2009, 33, 267.
B. Das, C. R. Reddy, D. N. Kumar, M. Krishnaiah, R. Narender,
Synlett., 2010, 3, 391.
9
5
10
15
20
25
10 Y. Lu, G. Just, Tetrahedron, 2001, 57, 1677.
11 Z. Zeng, y. Guo, B. Twamley, J. M. Shreeve, Chem. Commun.,
2009, 6014; H. Huang, Z. Zhou, L. Liang, J. Song, K. Wang, D.
Cao, C. Bian, W. Sun, M. Z. Xue, Z. Anorg. Allg. Chem., 2012,
638, 392; S. Garg, J. M. Shreeve, J. Mater. Chem., 2011, 21, 4787;
T. M. Klapötke, C. M. Sabaté, Chem. Mater., 2008, 20, 3629; T.
M. Klapötke, D. G. Piercey, J. Stierstorfer, Dalton Trans., 2012,
41, 9451; D. Sachin, M. J Gawande, M. R Raihan, Zanwar, K.
Veerababurao, D. Janreddy, C. W. Kuo, M. L. Chen, T. S. Kuo, C.
F. Yao, Tetrahedron, 2013, 69, 1841.
12 M. Zaheeruddin, Z. H. Lodhi, Phys. Chem. (Peshawar Pak.). 1991,
10, 111; P. Jimenez, M.V. Roux, C. Turrion, J. Chem.
Thermodyn., 1989, 21, 759; A. A. Balepin, V. P. Lebedev, E.A.
Miroshnichenko, G.I.
Koldobskii,
V.A.
Ostovskii, B.P.
Larionov, B.V. Gidaspov, Lebedev, A. Yu, Veshchestv Str. Mol.,
1977, 93.
13 T. P. Kofman, V. I. Namestnikov, Russian J. Org. Chem. 2003, 39,
579.
14 V. D. Ghule, D. Srinivas, K. Muralidharan, Asian J. Org. Chem.,
2013, 2, 662.
15 M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A.
Robb, J. R. Cheeseman, J. A. Montgomery, T. Vreven, , Jr, K. N.
Kudin, J. C. Burant, et al. Gaussian 03, revision A.1; Gaussian,
Inc.: Pittsburgh, PA, 2003.
30 16 D. W. M. Hofmann, Acta Crystallogr. Sect. B 2002, 58, 489–493.
17 M. J. Kamlet, S. J. Jacobs, J. Chem. Phys., 1968, 48, 23; M. J.
Kamlet, E. J. Ablard, J. Chem. Phys., 1968, 48, 36.
18 V. D. Ghule, P. M. Jadhav, R. S. Patil, S. Radhakrishnan, T.
Soman, J. Phys. Chem. A, 2010, 114, 498; V. D. Ghule, S.
35
Radhakrishnan, P. M. Jadhav, S. P. Tewari, J. Mol. Model., 2011,
17, 1507; X. J. Xu, H. M. Xiao, X. H. Ju, X. D. Gong, W. H. Zhu,
J. Phys. Chem. A, 2006, 110, 5929; V. D. Ghule, D. Srinivas, S.
Radhakrishnan, P. M. Jadhav, S. P. Tewari, Struct Chem., 2012,
23, 749; V. D. Ghule, J. Phys. Chem. A, 2012, 116, 9391.
40 19 E. F. C. Byrd, B. M. Rice, J. Phys. Chem. A, 2006, 110, 1005.
20 P. Politzer, J. S. Murray, M. E. Grice, M. Desalvo, E. Miller, Mol.
Phys., 1997, 91, 923; P. Politzer, J. S. Murray, Fluid Phase
Equilib., 2001, 185, 129.
21 F. A. Bulat, A. ToroꢀLabbe, T. Brinck, J. S. Murray, P. Politzer, J.
45
Mol. Model., 2010, 16, 1679.
22 H. D. B. Jenkins, J. Chem. Educ., 2005, 82, 950; L. Glasser, H. D.
B. Jenkins, J. Am. Chem. Soc., 2000, 122, 632; H. D. B. Jenkins,
D. Tudela, L. Glasser, Inorg. Chem., 2002, 41, 2364.
10
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