Synthesis and thermal decomposition of ditetrazol-5-ylamine

Article abstract of DOI:10.1007/s11172-006-0026-4

Ditetrazol-5-ylamine (DTA) was synthesized from cyanuric chloride in four steps. The thermal decomposition of DTA in the solid state was studied by thermogravimetry, volumetry, mass spectrometry, IR spectroscopy, and calorimetry. Under isothermal conditions at 200-242°C, thermal decomposition obeys the first order autocatalytic kinetics. The kinetic and activation parameters of DTA decomposition were determined. The composition of gaseous reaction products and the structure of condensed residue were studied. The thermal effect of thermal DTA decomposition is 281.4 kJ mol^-1. The nitrogen content in a mixture of gaseous products formed by the reaction in a temperature interval of 200-242°C exceeds 97 vol.%.

Full text of DOI:10.1007/s11172-006-0026-4

1
710
Russian Chemical Bulletin, International Edition, Vol. 54, No. 7, pp. 1710—1714, July, 2005
Synthesis and thermal decomposition of ditetrazolꢀ5ꢀylamine
V. V. Nedel´ko,ꢀ A. V. Shastin, B. L. Korsunskii, N. V. Chukanov, T. S. Larikova, and A. I. Kazakov
Institute of Problems of Chemical Physics, Russian Academy of Sciences,
1
42432 Chernogolovka, Moscow Region, Russian Federation.
Fax: +7 (096) 515 3588. Eꢀmail: vnedelko@icp.ac.ru
Ditetrazolꢀ5ꢀylamine (DTA) was synthesized from cyanuric chloride in four steps. The
thermal decomposition of DTA in the solid state was studied by thermogravimetry, volumetry,
mass spectrometry, IR spectroscopy, and calorimetry. Under isothermal conditions at
2
00—242 °С, thermal decomposition obeys the first order autocatalytic kinetics. The kinetic
and activation parameters of DTA decomposition were determined. The composition of gasꢀ
eous reaction products and the structure of condensed residue were studied. The thermal effect
of thermal DTA decomposition is 281.4 kJ mol– . The nitrogen content in a mixture of gaseous
products formed by the reaction in a temperature interval of 200—242 °С exceeds 97 vol.%.
1
Key words: ditetrazolꢀ5ꢀylamine, synthesis, thermal decomposition, kinetics, products,
IR spectroscopy, mass spectrometry, reaction mechanism.
Tetrazoles are considered as promising energyꢀcapacꢀ
ity compounds with a high nitrogen content. Some tetraꢀ
diate 2,4,6ꢀtris(methoxy)ꢀ1,3,5ꢀtriazine (2), 2,4ꢀbis(hydrꢀ
azino)ꢀ6ꢀmethoxyꢀ1,3,5ꢀtriazine (3), and 2,4ꢀbis(azido)ꢀ
6ꢀmethoxyꢀ1,3,5ꢀtriazine (4) (Scheme 1).
1
—3
zoles in mixtures with oxidizing agents are shown
to
form efficient gasꢀgenerating systems, which can be used
for the development of new facilities of individual protecꢀ
tion in transport (for instance, airbags for motorists). Gasꢀ
generating systems based on tetrazoles and their salts exꢀ
cel the presently used azide generators in the whole series
Kinetics of DTA thermal decomposition. The kinetic
curves of weight loss by the DTA samples under linear
heating conditions in air with a rate of 1.5 °С min– are
shown in Fig. 1. The hydrated form of DTA eliminates an
1
Н О molecule in the 120—150 °С temperature interval
2
3
of parameters. It should be mentioned that the nitrogen
(curve 1). The intensely developed process of formation
of volatile decomposition products occurs at temperatuꢀ
res >215 °С, while at 248 °С the sample ignites. The
preliminary total dehydration of DTA at 120 °С in vacuo
for 1 h does not change its thermal stability (see Fig. 1,
curve 2), and the ignition temperature of the anhydrous
content in ditetrazolꢀ5ꢀylamine exceeds 82 wt.%. Diꢀ
tetrazolꢀ5ꢀylamine (DTA) is interesting in the scientific
respect as a model compound revealing the mechanism of
thermal opening of the tetrazole ring. Specific features of
the structure of a DTA molecule make it possible to estiꢀ
mate the mutual influence of tetrazole rings through the
bridging NH group on the thermal stability of this comꢀ
pound. An ability of tetrazoles to form πꢀcomplexes with
–1
(
m – m)•m0 (%)
0
4
100
metals is of interest for syntheses of DTAꢀbased coordiꢀ
nation compounds, which can be used as medicines and
catalysts for combustion. The thermal decomposition of
DTA has not been studied. The kinetic study of thermal
decomposition and composition of destruction products
and the estimation of thermal effects of the reaction, conꢀ
ditions of ignition, and other specific features of the beꢀ
havior of DTA under heating seem necessary for practical
use of DTA and its safe operation. Although DTA is deꢀ
80
6
4
0
0
1
5
20
0
scribed, no detailed procedure of its synthesis was pubꢀ
lished.
2
5
0
100
150
200
T/°C
Results and Discussion
Fig. 1. Nonisothermal kinetics of decomposition of DTA
monohydrate (1) and dehydrated DTA (2) in air (weighed sample
10 mg, heating rate 1.5 deg min– ).
Synthesis of DTA. Ditetrazolꢀ5ꢀylamine was syntheꢀ
sized starting from cyanuric chloride (1) through intermeꢀ
1
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1660—1664, July, 2005.
066ꢀ5285/05/5407ꢀ1710 © 2005 Springer Science+Business Media, Inc.
1

Thermal decomposition of ditetrazolꢀ5ꢀylamine
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 7, July, 2005
1711
Scheme 1
6
sample increases to 254 °С. As known, if the dehydration
satisfactorily described by the first order autocatalysis
equation
of solid substances is endothermic, the sample cools down
and its temperature becomes lower than the temperature
of a heater. Perhaps, this is a reason for somewhat highꢀ
er ignition temperature of the preliminary dehydrated samꢀ
ple. Replacement of air with argon exerts virtually no
effect on the kinetics of DTA decomposition and does
not change its ignition temperature in the linear heating
regime, which indicates the absence of a noticeable conꢀ
tribution of thermal oxidation. The contribution of
DTA evaporation is observed under dynamic vacuum
conditions (permanent evacuation of volatile thermoꢀ
lysis products from the reaction zone) at temperatures
above 180 °С.
dα/dt = k (1 – α) + k α(1 – α),
(1)
1
2
where α is the conversion of the substance under study,
and k and k are the rate constants of noncatalytic and
1
2
catalytic reactions, respectively. Transformation of Eq. (1)
into the equation
(
dα/dt)/(1 – α) = k dt + k αdt
(2)
1
2
makes it possible to determine the absolute values of k1
and k at different experimental temperatures. These data
2
are given in Table 1.
The temperature plots for the rate constants k and k
1
2
Thermal decomposition of dehydrated DTA under isoꢀ
thermal conditions was studied in air in the temperature
interval 201—242 °С. The total weight loss corresponding
to complete DTA decomposition is close to 45 wt.%. The
kinetic curves (Fig. 2) are Sꢀshaped, and the process is
in the coordinates of the Arrhenius equation are shown in
Fig. 3. They are described by the equations
k1 = 1015.6±0.5exp[–(197±5)/(RT )],
k2 = 1017.5±0.7exp[–(201±7)/(RT )],
(3)
(4)
where k and k have a dimensionality of s–1, and R is of
–
1
1
2
(
m – m)•m
(%)
0
0
–1 –1
kJ mol
K
. The values of the preꢀexponential factor
5
4
3
2
1
0
4
3
Table 1. Rate constants of the noncatalytic (k1) and catalytic (k2)
routes of thermal decomposition of dehydrated DTA at different
temperatures from the data of thermogravimetry (weighed sample
2
0
0
0
1
0 mg) and calorimetry
Thermogravimetry
Calorimetry
1
T/°С
k1•107
k2•105
T/°С
k1•107
k •106
2
s–1
s–1
2
211
2
2
2
01
6.8±0.4
19±3
55±6
140±15
360±30
1.6±0.2
5.6±0.5
16±2
39±3
97±7
210
217
225
235
6.0±0.5
23±2
33±2
1.0±0.1
2.6±0.2
6.6±0.4
13±2
0
1
0
20
30
40
t/h
23
31
42
Fig. 2. Kinetics of thermal decomposition of dehydrated DTA
weighed sample 10 mg) in air at 201 (1), 211 (2), 223 (3),
31 (4), and 242 °С (5).
170±12
(
2

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712
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 7, July, 2005
Nedel´ko et al.
logk + 7/s–1
.2
more reliable, because they are close (see above) to the
activation parameters of thermal decomposition of tetraꢀ
zoles according to the first order kinetics (without selfꢀ
4
3
3
3
2
2
1
1
1
.8
.4
.0
.6
.2
.8
.4
.0
7
acceleration). The thermal effect of thermal DTA deꢀ
–1
composition is equal to 282±19 kJ mol
.
The volumetric data showed that each DTA molecule
eliminates two N molecules upon its complete decomꢀ
2
k2
position in the temperature interval 201—242 °С. The
volume fraction of nitrogen in a mixture of gaseous deꢀ
composition products is close to 97.5%. Purity of the
evolved nitrogen was confirmed by mass spectrometry.
The mass spectrum of the gaseous products of thermal
DTA decomposition obtained at 235 °С, reaction time
k1
1
h, and 100% decomposition depth indicates the formaꢀ
tion of nitrogen as a predominant gaseous product, small
amount of hydrocyanic acid (peaks with m/z 27, 26, and
T –1•10 /K
3
–1
1
.94
1.98
2.02
2.06
Fig. 3. Arrhenius plots of the rate constants of the noncataꢀ
lytic (k ) and catalytic (k ) routes of thermal decomposition of
2
5), and traces of Н О (~0.2 vol.%) and СО (<0.1 vol.%).
2 2
1
2
The N : HCN ratio is estimated as close to 50 : 1 (vol/vol).
2
dehydrated DTA in air (weighed sample 10 mg).
For deeper twoꢀstep DTA heating (235 °С, 1 h, and
4
50 °С), the qualitative composition of the gaseous deꢀ
(
1015.6 s–1) and activation energy (197 kJ mol–1) of the
composition products remains unchanged. However, in
the case of highꢀtemperature thermolysis of DTA, the yield
of hydrocyanic acid increases noticeably (N2 : HCN =
7
4
noncatalytic reaction are characteristic of thermal deꢀ
composition of tetrazoles.
The relation of the heat release rate dQ/dt to the conꢀ
version of DTA η obeys the first order autocatalysis
equation
7
: 1 vol/vol). The twoꢀstage regime of DTA heating to
50 °С is necessary, because the substance cannot be
heated to temperatures higher than 250 °С because of its
ignition.
dQ/dt (J mol–1 s–1) = k Q (1 – η) + k Q (1 – η)η,
(5)
1
f
2 f
The IR spectrum of the solid residue after complete
where η = Q/Q , Q is the heat released to the certain time
thermal DTA decomposition (240 °С, 0.5 h) is characterꢀ
f
ized by broad bands at 600—800 and 1200—1650 cm–
1
.
moment, and Q is the total heat of the process. The heats
f
Q and Q were determined by numerical integration of the
experimental time plot of the heat release rate.
Similar spectra with a ratio of stretching and bending
vibration frequencies of 2 : 1 are characteristic of disorꢀ
dered structures formed by planar networks (for instance,
for turbostrate boron nitride, layered aluminosilicates, and
some other). The basic NH groups that form weak hydroꢀ
gen bonds in a DTA molecule disappear during thermal
DTA decomposition (as indicated by the absence of an
f
The values determined for k and k are presented in
1
2
Table 1.
The heat release rates and thermal effects for DTA
thermal decomposition were measured by calorimetry
under conditions of spontaneous escape of volatile reacꢀ
tion products at temperatures 210—235 °С. The processꢀ
ing of the heat release curves for DTA thermal decompoꢀ
sition confirmed that the kinetic law of the firstꢀorder
catalytic process was fulfilled. The activation parameters
of the catalytic reaction calculated from the calorimetric
data (preꢀexponential factor and activation energy are
–
1
absorption band at 3450 cm ). The acidic NH groups
also disappear (no absorption bands are observed at
–
1
2400—2500 cm ). The solid decomposition product conꢀ
–
1
tains the NH groups (two bands at 3100—3300 cm and
2
–
1
a δ(NН ) band at 1630 cm ) and the NH groups forming
2
strong hydrogen bonds (perhaps, Аr=N—H, where Ar is
the conjugated heterocycle). The intense bands of stretchꢀ
1
6.2±1.3 –1
–1
1
0
s
and 205±14 kJ mol , respectively) are close
–
1
to the values measured by thermogravimetry. Despite conꢀ
siderable discrepancies of the activation parameters for
the noncatalytic reaction determined by calorimetry
ing vibrations at 1400—1600 and 1040 cm and bending
–
1
vibration bands at 700—800 cm indicate a possible presꢀ
8
ence of triazole rings.
2
3.0±1.6 –1
–1
(
10
s
and 270±15 kJ mol ) and thermograviꢀ
The solid product of complete thermal DTA decomꢀ
position at 200—242 °С is thermally stable at temperaꢀ
tures up to 300 °С. Deeper heating of the solid product
(450 °С, 1 h) is accompanied by the formation of compaꢀ
1
5.6
s–1 and 197 kJ mol ), the values obtained
–1
metry (10
for rate constants of the noncatalytic route can be exꢀ
plained by methodical difficulties associated with exact
determination of the rate constants k , which are lower
rable amounts of N and HCN and, as a consequence, the
1
2
than k , especially for calorimetric measurements. It can
N : HCN ratio decreases from 50 : 1 to 7 : 1 (vol/vol).
2
2
be assumed that the activation parameters of the nonꢀ
catalytic reaction determined by thermogravimetry are
When the solid product is deeply heated, its IR spectrum
changes noticeably. The IR spectrum of the solid product

Thermal decomposition of ditetrazolꢀ5ꢀylamine
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 7, July, 2005
1713
obtained by the twoꢀstage DTA thermolysis (235 °С, 1 h
and 450 °С, 1 h) has no absorption bands of the NH,
while the basic NH groups with strong hydrogen bonds
are retained. The latter is indicated by broad bands at
Polymeric triazoles are known to be thermally stable
1
0
up to 300 °С. The solid product obtained in our experiꢀ
ments by DTA decomposition in a temperature range of
200—240 °С is also stable to 300 °С. Further heating of
–
1
3
2
325 and 3190 cm in the spectrum. The weak bands at
176—2228 cm can be assigned to vibrations of the
this product affords comparable amounts of N and HCN.
2
–
1
Perhaps, the thermal decomposition of the triazole ring
С≡N bonds.
The following mechanism of DTA decomposition can
proceeds via Scheme 5.
be proposed based on the data of kinetic measurements,
mass spectrometry, and IR spectroscopy. In the studied
temperature interval from 200 to 240 °С, the decomposiꢀ
tion of DTA is preceded by its thermal tautomeric rearꢀ
rangement to the azidoazomethine form (Scheme 2).
Scheme 5
Scheme 2
The formation of the network structure (confirmed by
the IR spectra) can be due to a deeper thermal polymerꢀ
ization of the linear polymeric product (Scheme 6).
Scheme 6
Such a thermal rearrangement with tetrazole ring
9
opening is characteristic of Сꢀsubstituted tetrazoles. The
elimination of two nitrogen molecules from intermediate
diazide can produce isomeric triazoles (Scheme 3).
The appearance of nitrile groups in the solid product
of highꢀtemperature decomposition can be due to the
thermal destruction of the polymer (Scheme 7).
Scheme 3
Scheme 7
Aminotriazole contains the N=СH bond, which is
capable of thermal polymerization, and can transform
into polymeric triazole (Scheme 4).
Experimental
Ditetrazolꢀ5ꢀylamine monohydrate was synthesized in four
steps from cyanuric chloride in 40% yield. The structure of the
synthesized compound was confirmed by the С, Н NMR and
IR spectra. The kinetics of thermal DTA decomposition was
studied by thermogravimetry on an ATVꢀ14M automated therꢀ
mobalance, which enabled experiments on both linear heating
with different rates and under isothermal conditions in air,
vacuum, or inert atmosphere (krypton, argon). The kinetic studꢀ
ies of DTA decomposition by thermal release and measurements
of thermal effects of the process were carried out in open glass
13
1
Scheme 4
1
1
1
2
ampules on a DAKꢀ1 automated dynamic microcalorimeter.
The composition of the gaseous reaction products was deꢀ
termined by mass spectrometry on an MI1201ꢀV instrument and
by volumetry. IR spectra of the condensed decomposition prodꢀ
ucts were obtained on a Specordꢀ75IR spectrophotometer in
The formation of polymeric triazoles has been obꢀ
served earlier for the thermal decomposition of 2ꢀalkylꢀ
ꢀvinyltetrazole polymers. The structure assumed for polyꢀ
meric triazole agrees with the IR spectral data.
7
5
KBr pellets in an frequency region of 400—4000 cm–1
.

1
714
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 7, July, 2005
Nedel´ko et al.
2
,4,6ꢀTris(methoxy)ꢀ1,3,5ꢀtriazine (2). Sodium hydroxide
This work was financially supported by the Grants of
Council of the President of the Russian Federation (Proꢀ
gram of State Support for Leading Scientific Schools of
Russia, Grant NSh 00ꢀ15ꢀ97451).
(
12 g, 0.3 mol) was dissolved in MeOH (100 mL). Cyanuric
chloride 1 (18.5 g, 0.1 mol) was added to the resulting mixture
with cooling and stirring at such a rate that the temperature
would not exceed 30 °C. After compound 1 was added comꢀ
pletely, the reaction mixture was stored for 2 h at room temperꢀ
ature. A precipitate of NaCl formed was filtered off, methanol
was evaporated, and the residue was recrystallized from water.
The yield of 2 was 11.1 g (65%), m.p. 134—135 °С (Ref. 13:
References
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. H. Schmidt, N. Eisenreich, A. Baier, J. Neutz, D. Schroter,
1
34—136 °С).
,4ꢀBis(hydrazino)ꢀ6ꢀmethoxyꢀ1,3,5ꢀtriazine (3). Triazine 2
6.5 g, 38 mmol) was dissolved in THF (100 mL), and the
solution was refluxed with 100% hydrazine hydrate (5.7 g,
14 mmol) for 9 h. A precipitate formed was filtered off and
and V. Weiser, Propellants, Explosives, Pyrotechnics, 1999,
2
24, 144.
(
2
3
4
. T. Matsuzava, K. Sackata, J. Kaneko, J. Zhou Wu, M. Arai,
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1
dried in air to constant weight. The yield of 3 was 5.5 g (84%),
m.p. 231—232 °С. IR spectrum of 3 (KBr), cm–1: 3325, 3300,
270, 1600, 1590, 1570, 1555, 1495, 1395, 1355, 1130, 1095,
070, 1000, 940.
2
3.4 g, 19.8 mmol) was dissolved in an AcOH—H O (1 : 1)
mixture (20 mL). The resulting solution was cooled in an iceꢀ
cold bath, and a saturated aqueous solution of NaNO (3.5 g,
0 mmol) was added for 15 min with stirring and cooling. Then
cooling was stopped, stirring was continued for 20—25 min, and
the mixture was diluted to 50 mL. A precipitate formed was
filtered off, washed with a small amount of iceꢀcold water, and
dried on the filter to constant weight. The yield of 4 was 3.4 g
88%), m.p. 61—62 °С. IR (KBr), cm–1: 2175, 2130, 1580,
560, 1540, 1490, 1450, 1400, 1350, 1210, 1190, 1150.
Ditetrazolꢀ5ꢀylamine (DTA). Distilled water (250 mL) and
compound 4 (3.4 g) were placed in a roundꢀbottom 500ꢀcm3
flask with a reflux condenser. The mixture was refluxed for
3
1
,4ꢀBis(azido)ꢀ6ꢀmethoxyꢀ1,3,5ꢀtriazine (4). Compound 3
5
. Yu. A. Azev, I. P. Loginova, B. V. Golomolzin, I. I.
Mudretsova, and V. L. Rusinov, Khim. Geterotsikl. Soedin.,
(
2
1
990, No. 8, 135 [Chem. Heterocycl. Compd., 1990 (Engl.
2
Transl.)].
5
6
7
. N. Z. Lyakhov and V. V. Boldyrev, Usp. Khim., 1972, 41,
1
960 [Russ. Chem. Rev., 1972, 41 (Engl. Transl.)].
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(
1
8
9
. K. Nishiyama and J. Miyata, Bull. Chem. Soc. Jpn,
5
8, 2419.W
4
0—48 h until starting compound 4 disappeared (TLC monitorꢀ
ing on Silufol UV 254 plates). The solution was concentrated to
/2 volume and acidified with hydrochloric acid to acidic pH
litmus). A precipitate formed was filtered off, dried on the
filter, recrystallized from water, and dried for 2—3 h at 100 °С.
DTA was obtained in 40% yield (1.1 g). The substance decomꢀ
poses rapidly without melting at temperatures >220 °С, which
1
1
0. V. A. Lopyrev, V. N. Salaurov, V. N. Kurakin, L. A.
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1
(
1
985, 27, 145 [Polym. Sci. USSR, Ser. B, 1985, 27 (Engl.
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1
4 13
12. O. S. Galyuk, Yu. I. Rubtsov, G. S. Malinovskaya, and
G. B. Manelis, Fiz. Khim. [Physical Chemistry], 1965, 39,
2319 (in Russian).
agrees with published data.
s, N=C—N). H NMR (DMSOꢀd ), δ: 11.57 (br.s, NH of
C NMR (DMSOꢀd ), δ: 153.75
6
1
(
6
1
–
tetrazole and amine). IR (KBr), cm : 3440, 3250, 3125, 3025,
940, 2850 (against a broad absorption band, from 3300 to 2200
1
3. J. Thurston, J. Dudley, D. Kaiser, and F. Shaefer, J. Am.
Chem. Soc., 1951, 73, 72.
2
–
1
cm ), 1655, 1645, 1620, 1570, 1490, 1480, 1450, 1380, 1350,
1
4. W. P. Norris and R. A. Henri, J. Org. Chem., 1964, 29, 650.
1
1
340, 1325, 1280, 1275, 1260, 1245, 1230, 1175, 1130, 1105,
075, 1050, 1040, 1010, 1000, 860, 810, 750, 730, 725.
Literature data : C NMR (DMSOꢀd ), δ: 153.46 (s,
5
13
6
N=C—N); the IR spectrum contains a series of typical bands at
00—800, 900—1100, and 1500—1600 cm–1
Received May 21, 2004;
in revised form October 13, 2004
7
.