Investigation on the Sodium and Potassium Tetrasalts of 1,1,2,2-Tetranitraminoethane

Article abstract of DOI:10.1002/zaac.201600339

With respect to high-energy dense materials with high oxygen-content, the tetrasodium salt of 1,1,2,2-tetranitraminoethane as monohydrate Na₄TNAE·H₂O (4) and the tetrapotassium salt as dihydrate K₄TNAE·2H₂O (5) were synthesized and reported for the first time together with their crystal structures at 173 K. Whilst 4 cannot be dehydrated the crystal water content of 5 can be removed irreversibly at 160 °C to obtain K₄TNAE (6) as demonstrated by DTA and TGA measurements. K₄TNAE (6) was demonstrated using the small scale reactivity test to be a inferior explosive to RDX and CL-20. However the anionic nitramine compound was measured to be less toxic against Vibrio fischeri than RDX (EC₅₀: 240 mg·L^–1) with respect to its EC₅₀value above 15070 mg·L^–1. This demonstrates that the introduction of anionic nitramine moieties is a promising concept for the stabilization of energetic materials with lower toxicity.

Full text of DOI:10.1002/zaac.201600339

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DOI: 10.1002/zaac.201600339
Investigation on the Sodium and Potassium Tetrasalts of
1,1,2,2-Tetranitraminoethane
Maximilian Born,[a] Martin A. C. Härtel,[a] Thomas M. Klapötke,*[a]
Mathias Mallmann,[a] and Jörg Stierstorfer[a]
Keywords: High energy density materials; Nitramines; Alkali metals; Polyanions; Structure elucidation
Abstract. With respect to high-energy dense materials with high oxy-
gen-content, the tetrasodium salt of 1,1,2,2-tetranitraminoethane as scale reactivity test to be a inferior explosive to RDX and CL-20.
monohydrate Na4TNAE·H2O (4) and the tetrapotassium salt as dihy- However the anionic nitramine compound was measured to be less
TGA measurements. K4TNAE (6) was demonstrated using the small
drate K4TNAE·2H2O (5) were synthesized and reported for the first toxic against Vibrio fischeri than RDX (EC50: 240 mg·L–1) with respect
time together with their crystal structures at 173 K. Whilst 4 cannot
be dehydrated the crystal water content of 5 can be removed irrevers-
to its EC50 value above 15070 mg·L–1. This demonstrates that the in-
troduction of anionic nitramine moieties is a promising concept for the
ibly at 160 °C to obtain K4TNAE (6) as demonstrated by DTA and stabilization of energetic materials with lower toxicity.
In 2016 Fischer et al.[6] reported the synthesis of 1,1,2,2-
Introduction
tetranitratoethane (TNE), which is a powerful solid C,H,N,O
1,1,2,2-Tetranitraminoethane (TNAE) (3) has been first pub-
oxidizer with a high oxygen balance Ω(CO2) of 40.9%. The
lished in 1980 by Lee et al. in China.[1] In western literature
the synthesis of TNAE (3) appears first in a military report
isoelectronicity of the corresponding TNAE (3) tetraanion with
TNE and the lack of structure elucidation by X-ray diffraction
from 1982.[2] The scientists from Lawrence Livermore
was the motivation to synthesize the sodium and potassium
National Laboratory intended to use it as a building block for
salt of TNAE. The outstanding energetic properties of the
the synthesis of novel cycloaliphatic explosives containing the
TNAE salts that were reported in the literature should be veri-
secondary nitramine explosophore. The excellent acid-base re-
fied. Anionic nitramines are proposed structural motifs for the
activity of TNAE (3) has been reported by Daozheng in
stabilization of energetic materials by ionic interactions.[7] De-
1991.[3] A special focus was set on the tetrasodium salt
spite that the toxicity of the nitramine moieties in RDX (1,3,5-
Na4TNAE, which was reported with a crystal density of
trinitroperhydro-1,3,5-triazine) is the essential motivation for
the search of replacement compounds for this important
ubiquitious military explosive.[8] Bearing four anionic nitra-
2.11 g·cm–3 and a detonation velocity of 8995 m·s–1 at a den-
sity of 1.89 g·cm–3. Despite that an X-ray structure elucidation
of Na4TNAE has not been published. It was stated that the salt
mines the TNAE (3) tetraanion is an excellent model com-
is hygroscopic, which supposedly could be overcome by the
pound for the aquatic toxicity of anionic nitramines.
coating with TNT. In 2005 Lee et al.[4] published the tetrapo-
tassium salt K4TNAE (6) amongst the nitrogen-rich ammo-
nium and guanidinium derivatives. In 2011 Szala et al.[5] re-
ported a synthesis of TNAE (3) from glycoluril (1) without the
use of nitronium nitrate N2O5 and reported for the tetrasodium
salt Na4TNAE a detonation velocity of 10900 m·s–1 in combi-
nation with a detonation pressure of 42.7 GPa for the theoreti-
cal maximum density of 2.11 g·cm–3 based on calculations
with the CHEETAH code.
Results and Discussion
Synthesis
The synthetic route employed is based on the work of Szala
et al.[5] since it does not require the use of nitronium nitrate
N2O5 for the synthesis of tetranitroglycoluril (2). It was opti-
mized in several aspects, which shall be elucidated in the fol-
lowing. The fundamental principle of synthetic optimization in
the frame of this work is the abdication of purification steps
of the unstable synthetic intermediates tetranitroglycoluril
(TNGU) (2) and TNAE (3). TNGU (2) is known to be hydro-
lytically unstable[9] and TNAE (3) can only be properly stored
at –30 °C. The NMR spectra of 3 must be recorded instantane-
ously due to its slow decomposition in solution. Therefore
TNGU (2) and TNAE (3) were directly used as crude products
without purification for further synthesis and only the stable
* Prof. Dr. T. M. Klapötke
Fax: +49-89-2180-77492
www.hedm.cup.uni-muenchen.de
E-Mail: tmk@cup.uni-muenchen.de
[a] Department of Chemistry
University of Munich (LMU)
Butenandtstr. 5–13 (D)
81377 München, Germany
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/zaac.201600339 or from the au-
thor.
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salts Na4TNAE·H2O (4) and K4TNAE·2H2O (5) were purified X-ray Diffraction
by vapor diffusion recrystallization.
The solid-state structures of Na4TNAE·H2O (4) and
K4TNAE·2H2O (5) were determined by low temperature
The synthesis starts from commercially available glycoluril
(1), which can also be easily prepared by the acid-catalyzed
condensation of urea and glyoxal.[10] 1 can be nitrated four
times by the use of in situ generated acetyl nitrate in fuming
nitric acid. For the aqueous, alkaline hydrolysis and decarbox-
ylation of TNGU (2) Szala et al.[5] suggest the use of sodium
hydroxide (3 m, aq.). Under these conditions the reaction of
TNGU (2) is strongly exothermic and led twice to the auto-
ignition of reactant 2 during the addition. Therefore a lower
base concentration (1 m, aq.) was applied facilitating the ad-
dition of TNGU (2). With TNAE (3) in hands the synthesis of
the salts could be started. For Na4TNAE·H2O (4) the literature
procedure[5a] was applied using methanol as solvent. The syn-
thesis of K4TNAE·2H2O (5) was carried out in water. For both
salts the crude product was purified by gas-phase diffusion
of methanol in a highly concentrated aqueous solution of the
corresponding crude product. This cleanup step results in crys-
tals that are suitable for X-ray structure elucidation.
K4TNAE·2H2O (5) can be dehydrated to K4TNAE (6) at
160 °C in nearly quantitative yield (Figure 1). K4TNAE (6) is
not hygroscopic since the subjection of a sample to ambient
conditions for two weeks did not alter the results of elemental
analysis.
(173 K) single-crystal X-ray diffraction. Details on the mea-
surements and refinements are given in the Supplementary
Information. Cif files were deposited with the CCDC data-
base.[11] Single crystals containing crystal water of both com-
pounds were grown by slow diffusion of methanol into a satu-
rated aqueous solution of the corresponding compound. The
sodium salt crystallizes as a monohydrate (4) in the monoclinic
space group P21/n, the potassium salt as a dihydrate (5) in the
alternative space group P21/c. The densities at 173 K follow
the expected trend increasing within the group of alkali metal
salts (4: 2.060 g·cm–3, 5: 2.195 g·cm–3). The molecular moie-
ties are shown in Figure 2 and Figure 3. Both tetranitramino-
ethane tetraanions show very similar structures. The molecular
structures are also comparable to that of 1,1,2,2-tetranitrato-
ethane.[5] The bond lengths and angles (given in the figure
captions) agree nearly perfectly with literature values. The
hydrogen atoms in both structures are arranged trans to each
other with a planar H–C–C–H torsion angle in the case of 5
(180°) and almost planar in the case of 4 (177.8°). The middle
C–C bond in the tetraanions is a typical single bond (1.54 Å).
Both sp3 carbon atoms show expected tetrahedral surroundings
with C–N single bonds (1.46–1.47 Å). The adjacent N–N
bonds (1.27–1.28 Å) are closer to N=N double bonds (1.20 Å)
which supports the nitramine Lewis structure with both nega-
tive charges on the outer oxygen atoms as depicted in Figure 1.
Figure 1. Synthetic route for the synthesis of the target compounds
Na4TNAE·H2O (4), K4TNAE·2H2O (5), and K4TNAE (6).
Vibrational and NMR Spectroscopy
The crystal water absorptions in the IR spectra of 4 (3476,
3246 cm–1) and 5 (3486 cm–1) are absent in the case of anhy-
drous K4TNAE (6). The N–H functionality in TNAE (3)
causes a strong IR absorption at 3236 and 3146 cm–1, which
is absent in the IR spectra of compounds 4–6. All compounds
show the characteristic absorptions of the TNAE (3) tet-
raanion. Furthermore strong absorption bands associated with
the nitramine functionality can be observed at 1433/1388/
1332 cm–1 (4/5/6), 1392/1332/1372 cm–1 and 1289/1270/
Figure 2. Molecular moiety of 4 in the crystalline state. Ellipsoids
in both crystal structures drawn with Diamond2 represent the 50%
probability level. Selected bond lengths /Å: C1–C2 1.5366(15), N1–
C1 1.4649(15), C1–N3 1.4599(15), N1–N2 1.2721(14), N4–N3
1.2786(14), O1–N2 1.2869(13), O2–N2 1.2842(13), N4–O3
1.2688(13), N4–O4 1.2862(13). Selected bond angles /°: N3–C1–N1
107.04(9), N4–N3–C1 112.13(9). Selected torsion angles /°: N1–C1–
C2–N5 178.78(8).
Both structures form 3D networks, which are strongly domi-
1298 cm–1. The NMR spectra in D2O of 4 and 5 are almost nated by the following interactions: (i) electrostatic ion interac-
identical with a singlet at 5.97 (4) and 5.95 ppm (5) corre- tions, (ii) classical O–H···X hydrogen bonds, (iii) non-classical
sponding to the C–H functionality in the proton NMR spec- O–H···X hydrogen bonds, and (iv) nitro–nitro interactions. In
trum, a 13C signal at δ = 74.6 ppm, and a 14N signal at –25 ppm both structures the different alkaline metal salts do not form
corresponding to the nitro group.
regular coordination polyhedrons, e.g. the octahedral coordina-
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Thermogravimetric and Differential Thermal Analysis
The hydrated species Na4TNAE·H2O (4) and
K4TNAE·2H2O (5) have never been described in the literature.
Differential thermal analysis (DTA, see Figure 5) shows that
K4TNAE·2H2O (5) loses its crystal water content at 142 °C
and the unhydrated K4TNAE (6) decomposes at 225 °C. (lit.
value 284 °C)[4] Na4TNAE·H2O (4) decomposes without loss
of water at 197 °C. (lit. value 192 °C for unhydrated spe-
cies).[5a]
Figure 3. Molecular moiety of 5 in the crystalline state. Symmetry
codes: (i) –x, –y, 1–z; (ii) 1–x, –0.5+y, 0.5–z; (iii) –x, –y, –z; (iv) –1+x,
y, z. Selected bond lengths /Å: C1–C1i 1.542(3), N1–C1 1.4628(17),
N3–C1 1.4622(18), N1–N2 1.2864(16), N3–N4 1.2722(17), O1–N2
1.2709(15), O2–N2 1.2832(15), O3–N4 1.2837(16), O4–N4
1.2938(16). Selected bond angles /°: N3–C1–N1 109.78(11), N2–N1–
C1 112.13(11).
tion sphere, which is oftentimes observed for sodium salts. Se-
lected depictions on larger excerpts of the packing of
Na4TNAE·H2O (4) and K4TNAE·2H2O (5) are shown in Fig-
ure 4.
Figure 5. DTA thermogram of Na4TNAE·H2O (4) (grey line) and
K4TNAE·2H2O (5) (black line). Endothermic loss of water for com-
pound 5 at 142 °C Temperature of decomposition Tdec: 197 °C (4),
225 °C (5) (5 K·min–1 in glass vessel, Tmax values).
K4TNAE·2H2O (5) was analyzed by thermogravimetric
analysis (TGA, see Figure 6). Two water molecules
(36.03 g·mol–1) represent 7.87% the molecular weight of the
compound (458.51 g·mol–1). The temperature-mass plot re-
sulting from thermogravimetric analysis (2 K·min–1) shows
that from 50 °C to 152 °C one molecule of water is evaporated
continuously with a weight loss of 3.90%. The second mol-
ecule of water is lost with a high mass loss rate from 152 °C
to 156 °C with a total weight loss of 8.38%, which is in agree-
ment with the vaporization of two equivalents of water. The
discrepancy of 0.51% to the theoretical loss can be explained
by sublimation of the salt in the temperature regime investi-
Figure 6. Thermogravimetric analysis (2 °C min–1) of K4TNAE·2H2O
(5). Plot of temperature /°C vs. sample weight /%. Continuous loss of
Figure 4. View on the 3D crystal structure packing: (A) along the b mass from 50 to 152 °C, which corresponds to one equivalent of crys-
axis in Na4TNAE H2O (4) and (B) along the c axis in K4TNAE·2H2O tal water. The second crystal water equivalent is lost with a high mass
(5).
loss rate in the temperature range from 152 °C to 156 °C.
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gated. The sublimation of K4TNAE (6) also causes the mass Reactivity Test (SSRT)[14] was carried out to obtain a reliable
loss during the dehydration of 5, which indicates a solid-gas- experimental benchmark parameter for the energetic perform-
eous phase transition without decomposition. The temperature ance of the water-free compound K4TNAE (6). For this test a
range for water loss from TGA (142–156 °C, 2 K·min–1) is in steel block with a drill hole is placed on top of an aluminum
agreement with the endothermic peak area in the DTA (138– block. The drill hole is filled with the explosive and a detona-
152, 5 K·min–1).
tor is positioned over the explosive. After the detonation a dent
has been formed in the aluminum block. The dent is filled
with standardized SiO2, which is weighed. The mass ratio ε =
m(SiO2)/m(EXP) is a parameter for the energetic performance
of the explosive. It can be clearly stated that K4TNAE (6) (ε:
0.76) is outperformed by the military explosive RDX (ε: 1.17,
VDET: 8983 m·s–1, pCJ: 380 kbar)[8] and high-performance ex-
plosive CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexa-
Sensitivities
The sensitivities toward external stimuli and selected other
parameters of compounds 4–6 are compiled in Table 1. Sodium
salt 4 can be classified as very sensitive toward impact and
sensitive toward friction. The potassium compounds 5 and 6
can be classified as sensitive toward impact and insensitive
toward friction.[12] The sensitivity toward electrical discharge
of all salts 4–6 is above the 50 mJ discharge that can be gener-
ated by human interaction. Compounds 4–6 possess a positive
oxygen balance Ω ranging from 3.49% to 4.25% with the pos-
tulated combustion products CO2, H2O, N2, Na2O, and K2O.
Alternatively the same Ω values can be obtained with the metal
carbonates Na2CO3 and K2CO3 as a combination of the metal
oxide M2O with CO2. For K4TNAE (6) an enthalpy of forma-
tion of –1554 kJ·mol–1 was calculated on a CBS-4M level
using the Gaussian 09 software.[13] The strong exothermicity
of the compound is predominantly caused by the high lattice
enthalpy of the tetraanion salt and the high oxidation state of
all non-oxygen atoms. The densities of all compounds are in
the typical range for alkali metal salts of energetic C,H,N,O
compounds.
azaisowurtzitane) (ε: 1.72, VDET: 9455 m·s–1, pCJ: 467 kbar)[8]
The calculated detonation performance of Na4TNAE (VDET
.
:
10900 m·s–1, pCJ: 427 kbar) reported by Szala et al.,[5] which
would be in the range of CL-20 should be regarded critically
in comparison with the experimental performance of K4TNAE
(6) and CL-20 in the SSRT test. (cf. Table 2) K4TNAE (6) was
preferred over Na4TNAE·H2O (4) for the SSRT test since it
does not contain crystal water.
Table 2. Results of the SSRT test.
K4TNAE (6) RDX[8]
CL-20[8]
m(EXP)a)
m(SiO2)b)
ε = m(SiO2)/m(EXP) 0.76
586
445
504
589
1.17
550
947
1.72
a) Mass of explosive /mg. b) Mass of SiO2 /mg.
Aquatic Toxicity: EC50
Small Scale Reactivity Test (SSRT)
The calculation of detonation parameters relies extensively
K4TNAE (6) can be considered as an aliphatic C2H2 unit
on the detonation products formed during the detonation pro- connected to four anionic nitramines, which is highly water
cess. In case of alkali metal salts it is hard to state, which soluble (Ͼ662 g·L–1). Regarding the toxicity problem of
products are formed since the presence of these metal cations RDX,[8] a cycloaliphatic triazinane containing three secondary
might lead to the formation of metal oxides (Na2O, Na2O2, nitramines, it is interesting to investigate the toxicity of the
K2O), metal carbonates (Na2CO3, K2CO3) or other com- compound. The commercially available bioassay system
pounds. With this unknown detonation behavior the theoretical LUMIStox® analyzes the toxicity of a compound towards the
calculation of detonation parameters is an unreliable estimation marine, bioluminescent bacterium Vibrio fischeri. For toxico-
and was not used for compounds 4–6. Instead the Small Scale logical analysis the concentration which inhibits 50% of the
Table 1. Sensitivity toward external stimuli and other selected parameters of compounds 4–6.
Na4TNAE·H2O (4)
K4TNAE·2H2O (5)
K4TNAE·(6)
Formula
ISa) /J
C2H4Na4N8O9
2
240
300
C2H6K4N8O10
10
Ͼ360
1500
C2H2K4N8O8
4
Ͼ360
1500
FSb) /N
ESDc) /mJ
Grain size /μm
Nd) /%
100–500
29.80
+4.25
197
100–500
24.44
+3.49
142
Ͻ100
26.52
+3.79
225
Ωe) /%
f)
Tdec /°C
ρg) /g cm–3
2.060i
–
2.159i
–
2.152j
–1554
ΔfH0h) /kJ·mol–1
a) Impact sensitivity (BAM drophammer 1 of 6). b) Friction sensitivity (BAM friction tester 1 of 6). c) Sensitivity towards electrostatic discharge
(OZM research testing device). d) Nitrogen content. e) Oxygen balance [Ω = wO – 2C – 0.5yH – ‘0.5M (M: Na or K)]. f) Decomposition
temperature (Tmax from DTA /5 K·min). g) Density. h) Calculated (CBS-4M method) enthalpy of formation. i) Density from X-ray diffraction
at 173 K. j) Density from pycnometer at 298 K.
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using heating rates of 5 K·min–1. Thermogravimetric measurements
bioluminescence activity, the EC50 value, is determined after
were performed with a Perkin-Elmer TGA 4000 apparatus using a
heating rate of 2 K·min–1. Pycnometric measurements were carried out
with a Quantachrome Ultrapyc 1200 e pycnometer using the large
measurement cell. The EC50 values were determined with a Dr. Lange
LUMIStox 300 luminometer.
an incubation period of 30 min. For RDX an EC50 value of
240 mg·L–1 was observed. For K4TNAE (6) a first sign of inhi-
bition (26.7%) could be observed at a concentration of
15070 mg·L–1. The final EC50 value will be higher than this
concentration, yet it can already be stated that the toxicity of
K4TNAE (6) towards Vibrio fischeri is significantly lower by
a factor Ͼ60 than RDX. This result demonstrates that anionic
nitramines can be explosophores for future explosives with
high biocompatibility. The introduction of anionic nitramine
moieties to energetic materials has been proposed as a concept
for the stabilization of novel energetic materials by ionic inter-
actions.[7] Despite that it should be kept in mind that the bacte-
rial strain Vibrio fischeri is a relatively simple organism. The
environmental degradation products and toxicity towards
higher life forms of this attractive model compound 6 should
be further investigated.
CAUTION! All of the described compounds are energetic materials
with sensitivity to various stimuli. While we encountered no issues in
the handling of these materials, proper protective measures (face shi-
eld, ear protection, body armor, Kevlar gloves, and earthened equip-
ment) should be used during the handling of compounds 2–5 at all
times.
Tetranitroglycoluril (2): Glycoluril (1) (4.59 g, 32.30 mmol) was
added whilst stirring to fuming nitric acid (81 mL, 100%) in a 250 mL
round-bottomed flask at 0 °C. The dissolution is slightly exothermic.
After reaching 0 °C again, acetic anhydride (40.5 mL) was added drop-
wise over a period of 10 min. The temperature was lowered to 0 °C
and the ice bath was removed. The reaction mixture was stirred for 2
h letting the temperature rise to 35 °C. The mixture was cooled using
a water bath and was stirred for another 2 h, while keeping the tem-
perature at 20 °C. The crude product was filtered off, washed with ice
water (200 mL) and dispersed in a 3:1 mixture of chloroform and eth-
anol (90 mL) applying ultrasound. The colorless product was filtered
off and dried in a desiccator to yield 6.83 g (65.7%) of colorless tetra-
nitroglycoluril 2 as crude product for further synthesis. 1H NMR
Conclusions
The sodium salt Na4TNAE·H2O (4) and K4TNAE·2 H2O (5)
were synthesized and reported with their crystal structures at
173 K for the first time. Whereas sodium salt 4 cannot be de-
hydrated, the dihydrated potassium salt 5 can be dehydrated at
160 °C to K4TNAE (6). This in accordance with the results of
differential thermal analysis as an endotherm corresponding to
a loss of water was absent in the thermogram of 4 but present
in that of 5. The loss of two equivalents of water could be
demonstrated by thermogravimetric analysis of 5. Anhydrous
K4TNAE (6) was outperformed by the military explosive RDX
and high performance explosive CL-20 in the SSRT test. The
EC50 value aquatic bacteria of K4TNAE (6) (Ͼ15.07 g·L–1) is
more than 60 times higher than that of RDX (0.24 g·L–1). Be-
cause of these results anionic nitramines were demonstrated to
be a useful tool for the stabilization of energetic materials and
might be suitable explosophores for high energy density mate-
rials with decreased toxicity in comparison to the widely used
military explosive RDX.
(400.18 MHz, [D6]acetone):
δ
=
7.77 (s, C–H). 13C NMR
(100.64 MHz, [D6]acetone): δ = 65.9 (C-H), 142.4 (C=O). 14N NMR
(28.89 MHz, [D6]acetone), δ = –57 (NO2). IR (ATR): ν˜ = 3735 (w),
2997 (w), 2360 (m), 2341 (m), 1825 (s), 1797 (s), 1654 (m), 1621(s),
1595(s), 1369 (w), 1298 (m), 1258 (s), 1230 (m), 1212 (m), 1182 (m),
1147 (m), 1094 (s), 957 (w), 938 (w), 848 (w), 828 (w), 810 (m), 770
(w), 742 (m), 698 (m) cm–1. RAMAN: ν˜ = 3010 (1), 2999 (22), 1827
(6), 1799 (13), 1663 (3), 1639 (7), 1598 (4), 1386 (3), 1359 (7), 1314
(48), 1271 (5), 1214 (2), 1186 (5), 1043 (4), 960 (3), 850 (7), 834 (70),
771 (3), 723 (10), 699 (6), 521 (5), 471 (3), 440 (3), 420 (10), 340
(2), 312 (45), 220 (5), 174 (4), 93 (100) cm–1. C4H2N8O10 (322.11) C
15.37 (calcd. 14.92), H 0.89 (calcd. 0.63), N 34.27 (calcd. 34.79)%.
MS (DEI+): 322 (M+). IS: Ͼ5 J, FS: 80 N. ESD: 0.2 J [Ͻ100 μm].
DTA: Tbegin: 190 °C, Tonset: 208 °C, Tmax 215 °C, Toffset: 222 °C (de-
composition).
1,1,2,2-Tetranitraminoethane (TNAE) (3): A 250 mL round-bot-
tomed flask was placed in an ice bath and sodium hydroxide
(74.40 mL, 74.40 mmol, 4 equiv., aq., 1 M) solution were added.
TNGU (2) (6.00 g, 18.63 mmol) was added in small portions whilst
Experimental Section
All reagents and solvents were used as received (Sigma-Aldrich, stirring, keeping the temperature below 10 °C. Having completed the
Fluka, Acros Organics, ACBR). NMR spectra were measured with a
JEOL ECX-400 and a Bruker AVANCE 400 MHz NMR instrument.
The chemical shifts of the solvent peaks were adjusted according to
addition, the ice bath was removed and the reaction mixture was al-
lowed to stir for 1 h at room temperature. The reaction was quenched
by the slow addition of hydrochloric acid (37.2 mL, 74.40 mmol,
literature values [15]. Infrared spectra were measured with a Perkin- 4 equiv., aq., 2 M). The aqueous phase was extracted with diethyl ether
Elmer FT-IR Spektrum BXII instrument equipped with a Smith Dura (5ϫ30 mL) and the combined organic phases were dried with anhy-
SampIIR II ATR unit. Transmittance values are described as “strong” drous sodium sulfate. The drying agent was filtered off and the organic
(s), “medium” (m), and “weak” (w). Raman spectra were recorded
with a Bruker RAM II device (1064 nm, 300 mW). Relative peak in-
tensities are given in brackets. Elemental analyses (EA) were per-
formed with a Netsch STA 429 simultaneous thermal analyzer. Sensi-
tivity data were determined using a BAM drophammer and a BAM
friction tester. The electrostatic sensitivity tests were carried out using
an Electric Spark Tester ESD 2010 EN (OZM Research) operating
with the “Winspark 1.15” software package. The particle sizes stated
are valid for all sensitivity measurements. Melting and decomposition
points were measured with an OZM DTA 551-EX DTA apparatus
phase was removed using a rotary evaporator (0 mbar, 40 °C, 15 min).
TNAE (3) was obtained as colorless solid with a yield of 3.25 g (65%)
as crude product for further synthesis. 1H NMR (400.18 MHz,
[D6]DMSO): δ = 6.07 (s, C–H). 13C NMR (100.64 MHz, [D6]DMSO):
δ = 63.3 (C–H). IR (ATR): ν˜ = 3626 (w), 3480 (w), 3236 (s), 3146
(s), 3004 (m), 2361 (m), 2341 (w), 1768 (w), 1573 (s), 1448 (m), 1423
(m), 1323 (s), 1232 (s), 1162 (m), 1094 (m), 1061 (s), 930 (w), 835
(w), 774 (w), 695 (w), 667 (w) cm–1. RAMAN: ν˜ = 2997 (6), 1595
(6), 1404 (5), 1333 (18), 1162 (6), 1109 (4), 1020 (22), 934 (20), 840
(3), 828 (1), 739 (4), 677 (3), 661 (1), 601 (1), 435 (5), 344 (4), 323
Z. Anorg. Allg. Chem. 0000, 0–0
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Zeitschrift für anorganische und allgemeine Chemie
(1), 296 (2), 271 (1), 245 (7), 212 (4), 96 (100) cm–1. C2H6N8O8 Tetrapotassium 1,1,2,2-Tetranitramidoethane (K4TNAE) (6):
(270.12): C 9.59 (calcd. 8.89), H 2.46 (calcd. 2.24), N 40.65 (calcd.
K4TNAE·2H2O 5 (1.25 g, 2.73 mmol) was filled in a glass vessel,
which was placed in an oven and heated from room temperature to
160 °C for 4 h. After cooling to room temperature K4TNAE 6 (1.11 g,
96%) was obtained as a colorless powder. IR (ATR): ν˜ = 2956 (w),
2920 (w), 2361 (m), 2337(m), 1398 (s), 1372 (s), 1339(s), 1298 (s),
1247 (s),1129 (w), 1104 (m), 1016 (w), 1000 (w), 971(w), 958 (m),
771 (w), 743 (w), 721 (w), 657 (m) cm–1. RAMAN: ν˜ = 143 (22), 225
(3), 280 (4), 334 (3), 364 (5), 430 (4), 538 (11), 666 (4), 715 (3), 961
(6), 1004 (3), 1018 (42), 1107 (13), 1281 (3), 1340 (11), 1385 (9),
1400 (4), 1433 (13), 2028 (10), 2083 (19), 2228 (4), 2858 (100), 2925
(11), 2951 (4), 2962 (5) cm–1. C2H2K4N8O8 (422.48): C 5.89 (calcd.
5.69), H 0.57 (calcd. 0.48), N 26.22 (calcd. 26.52)%. IS: 4 J, FS:
Ͼ360 N. ESD: 1.5 J [Ͻ100 μm]. ρ298K (pycnometer): 2.152 g cm–3.
DTA: Tbegin: 208 °C, Tonset 224 °C, Tmax: 225 °C (decomposition).
41.48)%. MS (FAB-) 269 ((M–H)–). IS: 2 J, FS: 30 N. ESD: 0.1 J
[Ͻ100 μm]. DTA: Tbegin: 115 °C, Tonset: 131 °C, Tmax 136 °C, Toffset
:
139 °C (decomposition).
Tetrasodium
1,1,2,2-Tetranitramidoethane
Monohydrate
(Na4TNAE·H2O) (4): To methanol (250 mL) in a 500 mL round-bot-
tomed flask was added sodium hydroxide (1.4814 g, 37.04 mmol,
4 equiv.) and mechanical stirring was applied. The obtained solution
was cooled to 0 °C and TNAE (3) (2.5012 g, 9.26 mmol) was added
in one portion. The reaction mixture was stirred for 5 min at 0 °C and
methanol was removed using a rotary evaporator (30 mbar, 60 °C).
The colorless residue was dried in a desiccator under high vacuum to
yield 3.4012 g of crude product. For purification the crude product
(2.50 g) was dissolved in distilled water (3.56 mL). The solution was
filled in a 10 mL test tube, which was positioned in a vessel filled with
methanol. The vessel was closed to allow vapor diffusion of methanol
into the solution. After two weeks the formed crystals were collected
by filtration, washed with methanol and dried in high vacuum over
silica gel. 2.85 g (82%) Na4TNAE·H2O 4 was obtained as colorless
Crystallographic data (excluding structure factors) for the structures in
this paper have been deposited with the Cambridge Crystallographic
Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK.
Copies of the data can be obtained free of charge on quoting the de-
pository numbers CCDC-1408630 (4) and CCDC-1408628 (5)[11]
(Fax: +44-1223-336-033; E-Mail: deposit@ccdc.cam.ac.uk, http://
www.ccdc.cam.ac.uk).
1
crystals suitable for X-ray diffraction. H NMR (400.13 MHz, D2O):
δ = 5.97 (s, C–H). 13C NMR (100.62 MHz, D2O): δ = 74.6 (C–H).
14N NMR (28.91 MHz, D2O), δ = –25 (NO2). IR (ATR): ν˜ = 3626
(w), 3480 (w), 3236 (s), 3146 (s), 3004 (m), 2361 (m), 2341 (w), 1768
(w), 1573 (s), 1448 (m), 1423 (m), 1323 (s), 1232 (s), 1162 (m), 1094
(m), 1061 (s), 930 (w), 835 (w), 774 (w), 695 (w), 667 (w) cm–1.
RAMAN ν˜ = 2997 (6), 1595 (6), 1404 (5), 1333 (18), 1162 (6), 1109
(4),1020 (22),934(20), 840(3),828 (1),739(4), 677(3),661 (1),601(1),
435 (5), 344 (4), 323 (1), 296 (2), 271 (1), 245 (7), 212 (4), 96 (100)
cm–1. C2H4N8Na4O9 (376.06) C 6.65 (calcd. 6.39), H 1.11 (calcd.
1.07), N 29.50 (calcd. 29.80)%. IS: 2 J, FS: 240 N. ESD: 0.3 J [100–
500 μm]. DTA: Tbegin: 190 °C, Tonset 195 °C, Tmax: 197 °C (decompo-
sition).
Supporting Information (see footnote on the first page of this article):
Details on the X-Ray diffraction measurements and refinements of
compounds 4 and 5.
Acknowledgements
Financial support of this work by the Ludwig-Maximilian University
of Munich (LMU), the Office of Naval Research (ONR) under grant
no. ONR.N00014-16-1-2062, and the Bundeswehr – Wehrtechnische
Dienststelle für Waffen und Munition (WTD 91) under grant no.
E/E91S/FC015/CF049 and the Bundesministerium für Bildung und
Forschung (BMBF) under grant no. 13N12583 is gratefully
acknowledged. Ms. Regina Scharf is thanked for the measurement of
the EC50 values in this work. The authors acknowledge collaborations
with Dr. Mila Krupka (OZM Research, Czech Republic) in the devel-
opment of new testing and evaluation methods for energetic materials
and with Dr. Muhamed Suceska (Brodarski Institute, Croatia) in the
development of new computational codes to predict the detonation and
propulsion parameters of novel explosives. We are indebted to and
thank Drs. Betsy M. Rice, Jesse Sabatini and Brad Forch (ARL,
Aberdeen, Proving Ground, MD) for many inspired discussions.
Tetrapotassium
1,1,2,2-Tetranitramidoethane
Dihydrate
(K4TNAE·2H2O) (5): To water (120 mL) in a 250 mL round-bot-
tomed flask was added potassium hydroxide (85 wt-%, 1.21 g,
18.19 mmol, 4 equiv.) and mechanical stirring was applied. TNAE (3)
(1.2277 g, 4.55 mmol) was added to the obtained solution all at once.
The reaction mixture was stirred for 5 min and water was removed
using a rotary evaporator (30 mbar, 60 °C). The colorless crude prod-
uct (1.85 g, 97%) was dried in a desiccator. For purification the crude
product (1.38 g) was dissolved in distilled water (1.92 mL). The solu-
tion was filled in a 10 mL test tube, which was positioned in a vessel
filled with methanol. The vessel was closed to allow vapor diffusion
of methanol into the solution. After two weeks the crystals were col-
lected by filtration, washed with methanol and dried in high vacuum
over silica gel. 1.34 g (94%) K4TNAE·2H2O (5) was obtained as col-
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Received: September 16, 2016
Published Online: ᭿
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Journal of Inorganic and General Chemistry
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ARTICLE
Zeitschrift für anorganische und allgemeine Chemie
M. Born, M. A. C. Härtel, T. M. Klapötke*, M. Mallmann,
J. Stierstorfer ..................................................................... 1–8
Investigation on the Sodium and Potassium Tetrasalts of
1,1,2,2-Tetranitraminoethane
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