1058
KIZHNYAEV et al.
position 5 of the heteroring. The vinyl exchange reac-
tion with 4-nitro-5-phenyl-1,2,3-triazole (III) is likely
to result in formation of 4-nitro-5-phenyl-1-vinyl-
1,2,3-triazole (VI), for the largest downfield shift is
observed for the C4 signal (from 123.55 ppm in the
spectrum of III to 143.0 ppm).
Like other vinylazoles [8], the vinyl group in
N-vinyl-1,2,3-triazoles can be reduced under polaro-
graphic conditions at a potential E1/2 of about 2.7 V.
5-Nitro-1-vinyl-1,2,3-triazole gives rise to the second
reduction wave in a less negative potential region
due to reduction of the nitro group (see table). The
relative ease of electrochemical reduction of the vinyl
group in vinyltriazoles IV VI indicates their ability
to undergo polymerization.
To conclude, it should be noted that the catalytic
system mercury(II) acetate trifluoroacetic acid is
universal, i.e., it can be used in the synthesis of
N-vinylazole derivatives having two, three, and four
nitrogen atoms in the ring. This system is the most
advantageous in the synthesis of 1-vinyltetrazole.
With the other, previously known catalytic systems,
such as Hg(CH3COO)2/H2SO4 [9], Hg(CH3COO)2/
CH3COOH [10], and Hg(CH3COO)2/BF3 Et2O [11],
the reactions were characterized by poor reproduc-
ibility, and the yields were low. The use of the
Hg(CH3COO)2/CF3COOH system ensures consider-
able increase in the yield of 1-vinyltetrazole, sim-
plifies the experimental procedure, and makes the
process safer.
of sodium hydrogen carbonate. The product was
extracted into diethyl ether, the extract was dried over
anhydrous magnesium sulfate and evaporated, and
the residue was distilled under reduced pressure.
1-Vinyl-1,2,4-triazole was synthesized in a similar
way using 1,2,4-triazole as initial compound. Yield
90%, bp 103 C (15 mm), n2D0 = 1.5092.
1-Vinylimidazole was synthesized as described
above using imidazole as initial compound. Yield
71%, bp 80 C (10 mm), n2D0 = 1.5332.
5-Nitro-1-vinyl-1,2,3-triazole (V). A mixture of
16.5 g (0.14 mol) of 4-nitro-1,2,3-triazole, 4 g of
mercury(II) acetate, 4.5 ml of trifluoroacetic acid,
0.1 g of hydroquinone, and 200 ml of vinyl acetate
was stirred for 5 h at 70 C. The mixture was cooled
and treated with a concentrated aqueous solution of
sodium hydrogen carbonate. The organic layer was
separated, the aqueous layer was extracted with
diethyl ether, the extracts were combined with the
organic phase, and the solvent and excess vinyl
acetate were distilled off. The dry residue was recrys-
tallized from acetone.
4-Nitro-5-phenyl-1-vinyl-1,2,3-triazole (VI) was
synthesized in a similar way from 4-nitro-5-phenyl-
1,2,3-triazole.
1-Vinyltetrazole. A mixture of 40 g (0.57 mol)
of tetrazole, 10.8 g of mercury(II) acetate, 11 ml of
trifluoroacetic acid, 0.5 g of hydroquinone, and
200 ml of vinyl acetate was stirred for 2 h at 73 C.
Excess vinyl acetate was distilled off under reduced
pressure, the residue was poured into water, and the
product was extracted into methylene chloride. The
extract was dried over MgSO4, the solvent was dis-
tilled off, and the residue was distilled in a vacuum.
Yield 46 g (85%), bp 70 C (0.01 mm), n2D0 = 1.5010.
EXPERIMENTAL
The IR spectra were recorded on a Specord M-80
instrument from samples prepared as thin films or
suspensions in mineral oil. The UV spectra were
measured on a Specord UV-Vis spectrophotometer
Reaction of hydrazoic acid with acetylene.
A vertical 500-ml high-pressure reactor was charged
with a suspension of 65 g (1 mol) of sodium azide in
25 ml of water and 200 ml of benzene, and an open
ampule containing 50 ml of 65% sulfuric acid was
placed thereto. Acetylene was supplied to the reactor
to a pressure of 15 16 atm, and the mixture was
stirred for 60 h at 100 C. The reactor was opened,
the mixture was neutralized to pH 5 with sodium
hydrogen carbonate, the aqueous layer was separated
and treated with diethyl ether, and the extract was
combined with the organic phase, dried over magne-
sium sulfate, and distilled. We thus isolated 43 g
1
from solutions in acetonitrile. The H and 13C NMR
spectra were obtained on a Varian 500 spectrometer
at 500 and 125.6 MHz, respectively, using (CD3)2CO
as solvent. Polarographic measurements were per-
formed on an LP-7 polarograph with a dropping
mercury electrode; a solution of tetrabutylammonium
perchlorate in dimethylformamide was used as sup-
porting electrolyte.
1-Vinyl-1,2,3-triazole (IV). A mixture of 17.6 g
(0.26 mol) of 1,2,3-triazole, 4.75 g of mercury(II)
acetate, 4.8 ml of trifluoroacetic acid, and 0.1 g of
hydroquinone in 75 ml of vinyl acetate was stirred for
3 h at 70 C. Excess vinyl acetate was removed by
distillation under reduced pressure, and the residue
was neutralized with a concentrated aqueous solution
(40%) of 1,2,3-triazole, bp 80 81 C (4 mm), nD20
=
1.4985, and 12 g (8%) of 1-vinyl-1,2,3-triazole (IV),
bp 59 C (1 mm), n2D0 = 1.5130.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 7 2002