Russian Journal of Organic Chemistry, Vol. 40, No. 7, 2004, pp. 1069–1070. Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 7, 2004,
pp. 1110–1111.
Original Russian Text Copyright © 2004 by Zbarskii, Kuz’min, Yudin.
SHORT
COMMUNICATIONS
Synthesis and Properties
of 1-Nitro-4,5-dihydro-1H-1,2,4-triazol-5-one
V. L. Zbarskii, V. V. Kuz’min, and N. V. Yudin
Mendeleev Russian University of Chemical Technology, Miusskaya pl. 9, Moscow, 125047 Russia
e-mail: yudin@rctu.ru
Received November 14, 2003
While studying the kinetics of nitration of 1,2,4-
triazol-5-one in concentrated nitric acid by UV spec-
troscopy under the conditions leading to formation of
3-nitro-4,5-dihydro-1H-1,2,4-triazol-5-one [1, 2], we
found that in the first minutes 1-nitro-4,5-dihydro-1H-
1,2,4-triazol-5-one was formed and that the conversion
attained 80% in 100% nitric acid. Simultaneously,
the yield of 3-nitro-1,2,4-triazol-5-one considerably
decreased in 98–100% nitric acid. However, we failed
to isolate 1-nitro-4,5-dihydro-1H-1,2,4-triazol-5-one
from the reaction mixture. Although N-nitro deriva-
tives of heterocyclic compounds are well known [3],
we found no published data on derivatives having
an =N–N(NO)2–C(=O)– fragment.
served (1767 and 1719 cm–1, respectively); and C–H
stretching vibration band was present at 2840 cm–1.
The mass spectrum of 1-nitro-4,5-dihydro-1H-1,2,4-
triazol-5-one contained no molecular ion peak, but
strong peaks with m/z 101 [M + 1 – 30]+ and 85 [M + 1
– 46]+ were present, which correspond to elimination
of NO and NO2 from the molecular ion.
1-Nitro-4,5-dihydro-1H-1,2,4-triazol-5-one is very
readily hydrolyzed with water and aqueous bases, and
the reaction is accompanied by vigorous gas evolution.
The evolved gas consists of CO2, N2O, and N2 at
a molar ratio of 1.5:0.5:1, indicating cleavage of the
triazole ring; no nitrogen(IV) oxide was detected. The
product is more stable in dilute (1–3%) nitric acid
where it undergoes slow hydrolysis to 4,5-dihydro-1H-
1,2,4-triazol-5-one in several hours. The absorption
band of 1-nitro-4,5-dihydro-1H-1,2,4-triazol-5-one
(λmax 278 nm) disappears almost instantaneously from
the UV spectrum in concentrated sulfuric acid and tri-
fluoroacetic acid, and 3-nitro-4,5-dihydro-1H-1,2,4-tri-
azol-5-one is then slowly formed (λmax 316 nm).
1-Nitro-4,5-dihydro-1H-1,2,4-triazol-5-one was
synthesized by reaction of 4,5-dihydro-1H-1,2,4-tri-
azol-5-one with nitric acid in acetic anhydride. Its
1
structure was proved by H NMR spectroscopy: the
spectrum contained signals at δ 7.69 ppm (CH) and
9.80 ppm (NH). Splitting of the signal at δ 7.69 ppm
(J = 1 Hz) indicates the presence of a hydrogen atom
on the nitrogen neighboring to the CH group. In the
IR spectrum of the product, absorption bands due
to stretching vibrations of the nitro group (1326 and
1579 cm–1) are displaced relative to the corresponding
bands in the spectrum of 3-nitro-4,5-dihydro-1H-1,2,4-
triazol-5-one (1358 and 1548 cm–1); an appreciable
shift of the carbonyl absorption band was also ob-
Thermal decomposition (70°C, m/V = 5×10–4 g/cm3)
gives only 1.3 mol of gaseous products per mole of
the initial compound, and nitrogen(IV) oxide is absent.
The solid residue is characterized by an IR absorption
band at 2165 cm–1, which suggests the presence of
a C≡N group.
Scheme 1.
NO2
HN
HN
HN
65–100% HNO3
80–100% HNO3
N
N
N
O
O
O
N
N
N
H
H
NO2
98–100% HNO3
Decomposition products
1070-4280/04/4007-1069 © 2004 MAIK “Nauka/Interperiodica”