SYNTHESIS OF 1,4-DIPHENYL-3-PHENYLIMINO-1,2-DIHYDRO-1,2,4-TRIAZOLIUM HYDROXIDE 507
tra, on a Varian FT 80A (80 MHz) spectrometer in
from light green to red. The reaction mass was cooled
to room temperature and poured into a 25% aqueous
ammonia solution with ice. The resulting finely
divided yellow precipitate of Nitron V was filtered off
and reprecipitated from a mixture of glacial acetic acid
and ammonia solution (1 : 3 by volume). The reaction
product was dried in a vacuum oven at 50 60 C and
a pressure of 0.2 kg cm . The yield of Nitron reagent
was 176 g (74%), mp 186 188 C (dec.). Published
data: mp 189 C (dec.).
CDCl (with TMS as internal reference).
3
N,N-Diphenylcarbodiimide II. Thiourea I (300 g)
in 700 ml of benzene was refluxed with vigorous stir-
ring until water ceased to liberate (Dean Stark trap),
and 300 g of Pb O was added in portions. Desulfuri-
3
4
zation was regarded as complete when water ceased to
liberate. The sludge was separated, and diphenylcar-
bodiimide II was taken to the next step without isola-
tion.
2
Ttriphenylaminoguanidine IIIa. To the solution
of diimide II (see above), cooled to 10 C, 136 ml of
phenylhydrazine was added dropwise so that the tem-
perature in the reaction mixture was about 30 C. Then
100 ml of benzene was distilled off at atmospheric
pressure; 300 ml of isopropanol was added to the re-
maining solution, and the resulting mixture was kept
at 0 C for 8 10 h. The crystalline reaction product
was filtered off and dried in air; yield 350 g (88%),
mp 156 158 C.
Found (%): C 76.89, H 5.20, N 18.01.
C20H16N4.
Calculated (%): C 76.92, H 5.13, N 17.95.
1
IR spectrum (cm ): 3052 [ (CH
)], 2924
arom
1
[ (CH)], 572 [ (CH
)].
H NMR spectrum
arom
(CDCl ),
(ppm): 6.64 7.64 m (16H, Ph, CH).
3
CONCLUSION
1,4-Diphenyl-3-phenylimino-1,2-dihydro-1,2,4-
triazole IV. To 200 g of compound IIIa, 200 ml
of 40% aqueous solution of formaldehyde and 1.0 l of
isopropanol were added. The reaction mixture was
heated at 55 60 C for 0.5 h and cooled to 22 C.
The reaction product was filtered off, washed with
150 ml of isopropanol, and dried in air, which yielded
184 g (89%) of triazole IV; mp 126 128 C.
Conditions were developed for synthesis of high-
purity (98 wt %) Nitron reagent in the preparative
yield of 43% with the use of Pb O instead of lead
3
4
oxide (PbO ) and 2-propanol instead of ethanol.
2
REFERENCES
1. Babenko, A.S., Tolmachev, V.N., and Dzizin, A.N.,
1,4-Diphenyl-3-phenylimino-1,2-dihydro-1,2,4-
triazolium hydroxide V. To a solution of 240 g of
triazole IV in 1 l of isopropanol, glacial acetic acid
was added at 65 67 C until complete dissolution of
crystalline substance IV, which required 200 ml of
the acid. Then a solution of 88 g of sodium nitrite in
200 ml of water was added. The reaction was regarded
as complete when the color of the solution changed
Ukr. Khim. Zh., 1963, vol. 29, no. 7, pp. 702 708.
2. Hahn, H. and Wapen, K., Z. Anal. Chem., 1961,
vol. 182, no. 5, pp. 343 357.
3. Canteher, N. and Athanassova, D., Talanta, 1973,
vol. 20, no. 1, p. 125.
4. USSR Inventor’s Certificate 1556486.
5. Buch, M., Ber., 1905, vol. 38, no. 1, pp. 856 866.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 79 No. 3 2006