Nitration of carbonic, sulfuric and oxalic acid-derived amides in liquid carbon dioxide

Article abstract of DOI:10.1016/j.mencom.2013.03.008

N-Nitro- and N,N'-dinitroamides of carbonic, sulfuric and oxalic acids have been prepared in 76-99% yield by the nitration of the corresponding amides with dinitrogen pentoxide in liquid carbon dioxide.

Full text of DOI:10.1016/j.mencom.2013.03.008

Mendeleev
Communications
Mendeleev Commun., 2013, 23, 81–83
Nitration of carbonic, sulfuric and oxalic
acid-derived amides in liquid carbon dioxide
Ilya V. Kuchurov, Igor V. Fomenkov, Sergei G. Zlotin* and Vladimir A. Tartakovsky
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation.
Fax: +7 499 135 5328; e-mail: zlotin@ioc.ac.ru
DOI: 10.1016/j.mencom.2013.03.008
N-Nitro- and N,N'-dinitroamides of carbonic, sulfuric and oxalic acids have been prepared in 76–99% yield by the nitration of the
corresponding amides with dinitrogen pentoxide in liquid carbon dioxide.
O
Carbon dioxide, being an available, low cost, nontoxic, nonflam-
mable and thermally stable compound, is increasingly regarded
as a ‘green’ solvent in liquid (liq) or supercritical (sc) states for
chemical processes.1,2 Due to the specific physical and chemical
properties, CO2 media are particularly promising for nitration
reactions – an extremely important class of chemical reactions
widely used for manufacturing of energetic compounds3,4 and
drugs.5,6 Among these valuable properties are significant non-
flammability, resistance to strong oxidants, low viscosity, and
high diffusion rates2 (the latter is particularly useful for nitration
of poorly soluble substances such as polyamides or polymers7–9).
Furthermore, due to a considerably higher heat capacity of liq-
or sc-CO2 as compared to conventional solvents,10 they effectively
trap out exothermic reaction heat to reduce explosion risks of
nitration processes. Several successful syntheses of nitroarenes,11
nitroesters7–9,12 and N,N-dialkyl nitroamines13,14 in liq- or sc-CO2
have been reported. However, to the best of our knowledge, com-
pressed CO2 media have not been so far applied to the prepara-
tion of N-nitroamides, which are used as energetic compounds
themselves,15,16 and can be readily hydrolyzed to primary nitro-
amines hardly available via direct nitration protocols.4,17,18 Herein
we report the first synthesis of carbonic, sulfuric or oxalic acid-
derived N-nitro- and N,N'-dinitroamides by nitration of corre-
sponding amide derivatives in liquid CO2 (Scheme 1), the proce-
dure having been characterized by high product yields and lower
explosion risks than conventional nitration processes.
O
R2
R1
R1
R3
O
N
O
N
H
NO2
N2O5 (1.1–2.2 equiv.)
1a–c
2a–c
liquid CO2, 80 bar
0 °C, 5–120 min
R4
R4
R4
R4
X
X
N
N
N
N
H
H
NO2
4a–d
NO2
3a–d
O
1: a R1 = R2 = Et
b R1 + R2 = (CH2)2
c R1 = Et,
3, 4: a R4 = Me, X =
O
b R4 + R4 = (CH2)2, X =
R2 = (CH2)2NHCO2Et
O
O
2: a R1 = R3 = Et
b R1 + R3 = (CH2)2
c R1 = Et,
c R4 = Me, X =
d R4 = Me, X =
S
O
O
R3 = (CH2)2N(NO2)CO2Et
Scheme 1
linear bis-amide 1c (2.2 equiv. of the nitrating agent, 30 min)
whose both urethane fragments did react to afford bis-nitro-
carbamate derivative 2c in 98% yield (entry 4). N,N'-Dialkylureas
3a,b also reacted readily to furnish exhaustively nitrated products
4a,b in excellent yields. Among them, linear compound 3a exhi-
We employed dinitrogen pentoxide (N2O5) in these reactions
as a highly active, well-soluble in liq- or sc-CO2 and environment-
friendly (recoverable nitric acid is singularly generated as an acidic
secondary product19) nitrating agent.20–22 It had been used earlier
for nitration of similar amide and imide derivatives in organic
solvents, however, yields of corresponding N-nitroamides were
not always high.23 We found that urethane 1a reacted with N2O5
(1.1 equiv.) in liq-CO2 for 30 min to afford the corresponding
nitrourethane 2a in 96% yield (Table 1, entry 1).† Under similar
conditions, cyclic urethane 1b produced 3-nitrooxazolidin-2-one
2b, however, the reaction rate and product yield (entries 2 and 3)
were somewhat lower than those in the case of compound 1a.
Very high nitration efficiency was attained in the reaction of
Table 1 Nitration of urethane (1a–c) and bis-amide (3a–d) derivatives in
liquid CO2.a
N2O5
Time/ Isolated Reported yield (%)
Entry Product amount/
min
yield (%) (nitrating system)
equiv.
1
2
3
4
5
6
7
2a
2b
2c
1.1
1.1
2.2
30
60
120
30
5
96
62
76
98
95
96
99
86 (HNO3/Ac2O)24
80 (N2O5/CHCl3)22
95 (HNO3)17
86 (HNO3/Ac2O)15
60 (HNO3)15
4a
2.2
15
30
93 (N2O5 /CHCl3)25
†
8
4b
4c
2.2
2.2
60
93
41 [NH4NO3/(CF3CO)2O]26
The IR spectra were obtained on a Bruker ALPHA FT-IR spectrometer
in a thin film on NaCl plates or in KBr pellets. The H and 13C NMR
1
9
10
11
12
30
30
60
96
63
86
95
84 (HNO3)27
spectra were recorded on a Bruker AM-300 (300 MHz) instrument in
CDCl3 or DMSO-d6 using TMS as the internal standard. N,N'-bis(2-hydroxy-
ethyl)oxamide16 5 and dinitrogen pentoxide31 were prepared as described.
Starting compounds 1 and 3 were purchased from Acros Organics or
Sigma-Aldrich. Carbon dioxide (99.995%) was supplied by Linde Gas
(Russia).
4d
2.2
98 (HNO3/H2SO4)28
120
a The reactions were carried out using amides 1a–c or 3a–d (10.0 mmol) and
N2O5 (11.0–22.0 mmol) at 80 bar and 0°C.
© 2013 Mendeleev Communications. All rights reserved.
– 81 –

Mendeleev Commun., 2013, 23, 81–83
N2O5 (2.0 equiv.)
liquid CO2, 80 bar,
0 °C, 30 min
bited higher activity than imidazolidin-2-one 3b (entries 5–8).
O
H
The proposed conditions were found to be applicable to nitration
of sulfuric and oxalic amides 3c,d. In both cases the corresponding
bis-amides 4c,d were isolated in 95–96% yield (entries 9–12).
It is possible to further extend the developed procedure to the
nitration of polyfunctional compounds bearing hydroxy groups
along with the amide fragments. Nitration of N,N'-bis(2-hydroxy-
ethyl)oxalamide 5 gives either nitro ester 6 or fully nitrated
compound 7 in 85% or 90% yield, respectively, depending on
the reaction time (30 or 120 min) and the nitrating agent amount
(2 or 5 equiv.) (Scheme 2).‡ Product 7 had been earlier syn-
thesized16 by the action of a mixture of nitric and sulfuric acids
on compound 5, associated with the generation of mixed acid
wastes.
O2NO
N
N
H
ONO2
O
O
H
N
6 (85%)
HO
N
OH
H
O
5
O
NO2
O2NO
N
N
ONO2
N2O5 (5.0 equiv.)
liquid CO2, 80 bar,
0 °C, 120 min
NO2
O
7 (90%)
Scheme 2
The experiments in an autoclave equipped with sapphire
windows show that all studied reactions are heterogeneous under
the conditions used. High efficiency of the developed nitration
procedure in spite of poor solubility of starting amides and reac-
tion products in liq-CO2 may be attributed to a high diffusion
rate of N2O5-solute in the liquid CO2 medium that results in an
efficient nitrating agent delivery to the solid surface of the hetero-
geneous substrate. The proposed approach may be considered as
environmentally benign since it does not employ toxic organic
solvents of the non-renewable hydrocarbon origin. The procedure
is convenient: after decompression, the products can be isolated
from the residue by washing with water and diluted nitric acid
as well as volatile carbon dioxide can be, if needed, recycled.
Furthermore, an opportunity to prepare starting urea derivatives
General nitration procedure.12–14 A steel autoclave (25 cm3) equipped
with sapphire windows containing urethane 1c or amide 3 or 5 (10.0 mmol)
was filled with liquid CO2 to 60 bar pressure and cooled to 0°C. Then
N2O5 (2.4 g, 22.0 mmol) solution in liquid CO2 (~4 g) cooled to 0–5°C
was gradually pressed out from an auxiliary high-pressure cell by a fresh
CO2 flow (2 g min–1) to the reaction autoclave. During the addition, the
pressure in the latter raised up to 80 bar. The reaction mixture was stirred
at 0–5°C for the time specified in Table 1. Then, CO2 was removed by
decompression and the residue was poured onto ice water (50 ml). The
resulted suspension was extracted with EtOAc (4×20 ml), the combined
organic extracts were washed successively with saturated aqueous NaHCO3
(2 × 20 ml) and water (25 ml) and dried over anhydrous Na2SO4. The
solvent was removed under reduced pressure to afford corresponding nitro
compounds 2, 4 (see Table 1). Compounds 2a,b and 7 were synthesized
by similar procedures using 1.2 g (11.0 mmol) or 6.0 g (55 mmol) of
N2O5, respectively.
29
3a,b from the corresponding amines (diamines) and sc-CO2
makes the process even more attractive. Synthesized compounds
2a,c and 4a,c are used as precursors of practically important
methylnitramine18,30 and ethylenedinitramine,17 including produc-
tion on a commercial scale.18
In summary, an efficient explosion-proof procedure for the
syntheses of carbonic, sulfuric and oxalic acid-derived N-nitro-
and N,N'-dinitroamides by nitration of corresponding NH-pre-
cursors with N2O5 in the liquid carbon dioxide medium has been
developed. The proposed procedure advantages are the toxic
organic solvents exclusion and environmental and technological
safety improvement owing to the explosive reaction mixture
dilution with inert carbon dioxide.
N-Ethyl-N-nitrocarbamic acid ethyl ester 2a: yellow oil. IR (n/cm–1):
2988, 2942, 1773, 1742, 1576, 1448, 1377, 1337, 1300, 1242, 1177,
1
1089, 1023, 991, 876, 808, 750, 610. H NMR (DMSO-d6) d: 4.37 (q,
2H, NCH2Me, J 7.1 Hz), 4.11 (q, 2H, OCH2Me, J 6.9 Hz), 1.37 (t,
3H, NCH2Me, J 7.1 Hz), 1.27 (t, 3H, OCH2Me, J 6.9 Hz). 13C NMR
(DMSO-d6) d: 13.58 (OCH2Me), 46.63 (OCH2Me), 64.70 (CH2NNO2),
149.46 (C=O).
3-Nitro-1,3-oxazolidin-2-one 2b: white solid, mp 107–109°C (lit.,32
110–111°C). IR (n/cm–1): 3436, 1797, 1573, 1560, 1478, 1312, 1286, 1216,
1162, 1098, 1036, 977, 838, 761, 740, 707, 617. 1H NMR (DMSO-d6) d:
4.25–4.46 (m, 4H, NCH2CH2O). 13C NMR (DMSO-d6) d: 45.37 (CH2O),
60.91 (CH2NNO2).
N,N'-Dinitro-N,N'-ethanediylbis(carbamic acid) diethyl ester 2c: white
solid, mp 80–82°C (lit.,17 82–82.5°C). IR (n/cm–1): 3411, 1735, 1723,
1707, 1644, 1586, 1434, 1280, 1249, 1098, 990, 972, 892, 844, 760,
714, 591, 565. 1H NMR (DMSO-d6) d: 4.39 (s, 4H, CH2NNO2), 4.25 (q,
4H, OCH2Me, J 7.1 Hz), 1.24 (t, 6H, OCH2Me, J 7.1 Hz). 13C NMR
(DMSO-d6) d: 13.58 (OCH2Me), 46.63 (OCH2Me), 64.70 (CH2NNO2),
149.46 (C=O).
N,N'-Dimethyl-N,N'-dinitrourea 4a: yellow oil. IR (n/cm–1): 2955, 1775,
1719, 1570, 1514, 1390, 1315, 1253, 1163, 1041, 989, 883. 1H NMR
(CDCl3) d: 3.64 (s, 6H, MeNNO2). 13C NMR (CDCl3) d: 36.51 (MeNNO2),
148.43 (C=O).
This work was supported by the Russian Foundation for Basic
Research (grant nos. 11-03-12163-ofi_m and 12-03-12012-ofi_m).
References
1 P. T. Anastas and J. C. Warner, Green Chemistry: Theory and Practice,
Oxford University Press, New York, 2000.
2 P. G. Jessop and W. Leitner, Chemical Syntheses Using Supercritical
Fluids, Wiley-VCH, Weinheim, 1999.
3 R. Meyer, J. Köhler and A. Homburg, Explosives, 6th edn., Wiley-VCH
Verlag GmbH, Weinheim, 2007.
4 J. P. Agrawal and R. D. Hodgson, Organic Chemistry of Explosives, Wiley
Interscience, New York, 2007.
5 M. H. Litchfield, J. Pharm. Sci., 2006, 60, 1599.
6 J. Ahlner, R. G. Andersson, K. Torfgard and K. L. Axelsson, Pharmacol.
Rev., 1991, 43, 351.
7 R. E. Farncomb and G. W. Nauflett, Waste Manag., 1997, 17, 123.
N,N'-Dinitro-1,3-diazacyclopentan-2-one 4b: white solid, mp 211–212°C
(lit.,26 213°C). IR (n/cm–1) 3434, 1796, 1582, 1561, 1315, 1282, 1245, 1218,
1159, 1140, 1101, 757, 741, 717, 705. 1H NMR (DMSO-d6) d: 4.12 (s, 4H,
CH2NNO2). 13C NMR (DMSO-d6) d: 41.18 (CH2NNO2), 142.22 (C=O).
N,N'-Dimethyl-N,N'-dinitrosulfamide 4c: white solid, mp 89–90°C
(lit.,27 89.5–90°C). IR (n/cm–1): 3421, 1598, 1411, 1292, 1193, 1117,
904, 794, 747, 650, 572. 1H NMR (DMSO-d6) d: 3.76 (s, 6H, MeNNO2).
13C NMR (DMSO-d6) d: 38.96 (MeNNO2).
N,N'-Dimethyl-N,N'-dinitrooxalamide 4d: white solid, mp 123–124°C
(lit.,28 124°C). IR (n/cm–1): 3414, 2964, 1732, 1706, 1600, 1572, 1419,
1345, 1254, 1181, 1098, 999, 952, 824, 767, 724, 574. 1H NMR (DMSO-d6)
d: 3.65 (s, 6H, MeNNO2). 13C NMR (DMSO-d6) d: 32.51 (MeNNO2),
158.62 (C=O).
‡
N,N'-Bis(2-nitryloxyethyl)oxalamide 6: white solid, mp 147–149°C
(lit.,16 148.2°C). IR (n/cm–1): 3316, 1659, 1632, 1529, 1436, 1363, 1279,
1121, 1005, 879, 852, 756, 669, 563. 1H NMR (DMSO-d6) d: 8.98 [s, 2H,
C(O)NHCH2], 4.61 (t, 4H, CH2ONO2, J 5.0 Hz), 3.51 (t, 4H, NCH2CH2,
J 5.3 Hz). 13C NMR (DMSO-d6) d: 36.47 (NCH2CH2), 71.66 (CH2ONO2),
160.07 (C=O).
N,N'-Bis(2-nitryloxyethyl)-N,N'-dinitrooxalamide 7: white solid, mp 90–
92°C (lit.,16 91–92°C). IR (n/cm–1): 3411, 1735, 1707, 1644, 1586, 1434,
1280, 1249, 1098, 990, 972, 892, 844, 760, 714, 665, 591, 565. 1H NMR
(DMSO-d6) d: 4.87 (t, 4H, NCH2CH2, J 4.5 Hz), 4.62 (t, 4H, CH2ONO2,
J 4.5 Hz). 13C NMR (DMSO-d6) d: 43.43 (CH2ONO2), 68.85 (NCH2CH2)
158.09 (C=O).
– 82 –

Mendeleev Commun., 2013, 23, 81–83
8 G. W. Nauflett and R. E. Farncomb, JANNAF Propellant Development
21 P. Golding, R. W. Millar, N. C. Paul and D. H. Richards, Tetrahedron,
& Characterization Subcommittee and Safety & Environmental Protec-
tion Subcommittee Joint Meeting, US, 1998, p. 14.
1993, 49, 7051.
22 R. W. Millar and S. P. Philbin, Tetrahedron, 1997, 53, 4371.
23 J. von Runge and W. Triebs, J. Prakt. Chem., 1962, 15, 233.
24 H. M. Curry and J. P. Mason, J. Am. Chem. Soc., 1951, 73, 5043.
25 G. V. Caesar and M. Goldfrank, US Patent 2400288, 1946 (Chem. Abstr.,
1946, 40, 23123).
26 S. C. Suri and R. D. Chapman, Synthesis, 1988, 9, 743.
27 O. V. Anikin, L. G. Gareeva, I. E. Chlenov, V. A. Tartakovskii, Yu. T.
Struchkov, V. S. Kuz’min andYu. N. Burtsev, Izv. Akad. Nauk SSSR, Ser.
Khim., 1989, 1812 (Bull. Acad. Sci. USSR, Div. Chem. Sci., 1989, 38,
1659).
9 R. E. Farncomb and G. W. Nauflett, US Patent 6177033, 2001 (Chem.
Abstr., 2001, 134, 118045).
10 R. Span and W. Wagner, J. Phys. Chem. Ref. Data, 1996, 25, 1509.
11 N. Chanhan, M. E. Colclough and J. Hamid, Proceedings of the 6th Meeting
on Supercritical Fluids, Nottingham, UK, 1999.
12 I. V. Kuchurov, I. V. Fomenkov, S. G. Zlotin and V. A. Tartakovsky,
Mendeleev Commun., 2012, 22, 67.
13 I. V. Kuchurov, I. V. Fomenkov and S. G. Zlotin, Izv. Akad. Nauk, Ser.
Khim., 2009, 1995 (Russ. Chem. Bull., Int. Ed., 2009, 58, 2058).
14 I. V. Kuchurov, I. V. Fomenkov and S. G. Zlotin, Izv. Akad. Nauk, Ser.
Khim., 2010, 2093 (Russ. Chem. Bull., Int. Ed., 2010, 59, 2147).
15 K. Shiino and S. Ikinuma, US Patent 2997501, 1962 (Chem. Abstr.,
1962, 56, 12828).
28 O. C. W. Allenby and G. Wright, Can. J. Res., 1947, 25B, 295.
29 C. Wu, H. Cheng, R. Liu, Q. Wang, Y. Hao, Y. Yu and F. Zhao, Green
Chem., 2010, 12, 1811.
30 M. S. Chang and R. S. Orndoff, US Patent 394218, 1983 (Chem. Abstr.,
16 R. S. Stuart and G. F. Wright, Can. J. Res., 1948, 26B, 401.
17 W. E. Bachmann,W. J. Horton, E. L. Jenner, N. W. MacNaughton and
C. E. Maxwell, J. Am. Chem. Soc., 1950, 72, 3132.
1983, 98, 182088).
31 Inorganic Syntheses, ed. L. F. Audrieth, McGraw-Hill, NewYork, 1950,
vol. III, p. 78.
18 G. W. Nauflett, US Patent 4513148, 1985 (Chem. Abstr., 1985, 98,
182087).
32 R. L. Willer, C. G. Campbell and R. F. Storey, J. Heterocycl. Chem.,
2012, 49, 421.
19 R.W. Millar, M. E. Colclough, A. W. Arber, R. P. Claridge, R. M. Endsor
and J. Hamid, in Energetic Materials: Chemistry, Hazards and Environ-
mental Aspects, eds. J. R. Howell and T. E. Fletcher, Nova Science Pub.
Inc., New York, 2010.
20 P. Golding, R. W. Millar, N. C. Paul and D. H. Richards, Tetrahedron
Lett., 1988, 29, 2731.
Received: 23rd January 2013; Com. 13/4053
– 83 –