1.5 h at room temperature, water (150 ml) was added, and it was heated on a water bath at 50°C for 15 min and
then cooled down to room temperature. The precipitate was washed on the filter with water, dried in air, and
recrystallized from a water–DMF mixture. Yield 0.92 g (76%); mp 162-163°C. IR spectrum (KBr), , cm-1:
ν
2232 (CN), 1621 (C=N), 3270 (N–H). UV spectrum (EtOH), λmax, nm (log ): 203.2 (2.09), 216.8 (1.94)
ε
(inflection point), 257.6 (1.83), 319.2 (1.59) (inflection point), 350.4 (1.65), 398.4 (1.57 (inflection point).
Found, %: C 62.01; H 2.37; N 36.31. C10H5N5. Calculated, %: C 61.53; H 2.58; N 35.88.
Other hydrazones 3 were obtained similarly from the corresponding bisulfates 2 and malonic acid
dinitrile.
(4-Bromo-2-cyanophenyl)hydrazone of Mesoxalic Acid Dinitrile (3) (R = Br). Yield 83.8%;
mp 175-176°C (H2O–DMF). IR spectrum (KBr), , cm-1: 2240 (CN), 1615 (C=N), 3240 (N–H). UV spectrum
ν
(EtOH), λmax, nm (log ): 205.6 (1.91), 216.0 (1.83) (inflection point), 268.0 (1.56), 348.0 (1.45), 403.2 (1.56).
ε
Found, %: C 43.29; H 1.43; N 26.17. C10H4BrN5. Calculated, %: C 43.82; H 1.47; N 25.68.
(2-Cyano-4-nitrophenyl)hydrazone of Mesoxalic Acid Dinitrile (3) (R = NO2). Yield 66.9%;
mp 201-202°C (H2O–DMF). IR spectrum (KBr), , cm-1: 2182 (CN), 1628 (C=N), 3240 (N–H), 1564, 1368
ν
(NO2). UV spectrum (EtOH), λmax, nm (log ): 203.2 (2.03), 221.6 (1.94), 263.2 (1.61), 320.8 (1.79). Found, %:
ε
C 50.13; H 1.87; N 35.27. C10H4N6O2. Calculated, %: C 50.00; H 1.68; N 34.89.
3,5-Diamino-4-(2-cyanophenyl)azopyrazole (1) (R = H). Hydrazine hydrate (1 ml, 0.02 mol) was
added to hydrazone 3 (R = H) (0.78 g, 0.004 mol) in alcohol (30 ml). The mixture was boiled for 3 h; most of
the liquid was driven off under vacuum. The residue was filtered off, washed on the filter with alcohol, dried in
air, and recrystallized from propanol. Yield 0.496 g (54.5%); mp 165-167°C. IR spectrum (KBr), , cm-1: 2222
ν
(CN), 1414 (N=N), for NH2, 3436 (N–H), 1658 (C–N), 3360 (N–H). UV spectrum (EtOH), λmax, nm (log ):
ε
207.2 (2.00), 228.0 (1.70) (inflection point), 271.2 (1.81), 327.2 (1.81), 377.6 (1.51). Found, %: C 52.37;
H 3.96; N 42.78. C10H9N7. Calculated, %: C 52.87; H 3.99; N 43.17.
Other compounds 1 were obtained similarly from the corresponding 3 and hydrazine hydrate.
4-(4-Bromo-2-cyanophenyl)azo-3,5-diaminopyrazole (1) (R = Br). Yield 65.4%; mp 195-196°C
(propanol). IR spectrum (KBr), , cm-1: 2220 (CN), 1412 (N=N), for NH2, 3488 (N–H), 1636 (C–N), 3312 (N–H).
ν
UV spectrum (EtOH), λmax, nm (log ): 208.0 (2.12), 232.2 (1.316) (inflection point), 276.2 (1.77), 328.8 (1.57),
ε
400.8 (1.63). Found, %: C 39.29; H 2.41; N 32.43. C10H8BrN7. Calculated, %: C 39.29; H 2.41; N 32.41.
4-(2-Cyano-4-nitrophenyl)azo-3,5-diaminopyrazole (1) (R = NO2). Yield 78%; mp 235-237°C
(propanol). IR spectrum (KBr), , cm-1: 2228 (CN), 1426 (N=N), for NH2, 3360 (N–H), 1626 (C–N), 3312 (N–H),
ν
1520, 1370 (NO2). UV spectrum (EtOH), λmax, nm (log ): 203.2 (2.03), 223.2 (2.04), 261.6 (1.81), 323.2 (2.05).
ε
Found, %: C 44.13; H 2.87; N 40.61. C10H8N8O2. Calculated, %: C 44.12; H 2.96; N 41.16.
REFERENCES
1.
M.-G. A. Shvekhgeimer, O. A. Moreva, and T. I. Yakovenko, Dokl. Akad. Nauk, 360, 206 (1999).
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