Studies with 2-arylhydrazononitriles: Further investigations on reactivity of 2-arylhydrazononitriles towards hydroxylamine

Article abstract of DOI:10.1002/jhet.5570450405

(Chemical Equation Presented) The utilization of arylhydrazononitriles (6-9) for synthesis of azoles is demonstrated. Thus, arylazomalononitriles (6) reacted with hydroxylamine hydrochloride to afford isoxazol-5-imine (10), amidoxime (12) and bis-amidoxim

Full text of DOI:10.1002/jhet.5570450405

Jul-Aug 2008
975
Studies with 2-Arylhydrazononitriles: Further Investigations on
Reactivity of 2-Arylhydrazononitriles Towards Hydroxylamine
Sayed M. Riyadh,a Hamad M. Al-Matara* and Mohamed H. Elnagdib
aChemistry Department; Faculty of Science; University of Kuwait; P.O. Box 5969; Safat; 13060-Kuwait.
Tel.: +965-4987559; fax: +965-4816482; E-mail address: almatarc60@hotmail.com
bDepartment of Chemistry; Faculty of Science; Cairo University, Giza; A. R. Egypt
Received March 18, 2007
OH
N
R
NH2
N
Ar
N
H
R = CN
R = Ph
R = CN
R = 2-Thiazolyl
Pip/ DMF
NH2OH.HCl
Ac2O/ AcOH
Pip/ DMF
EtOH/ AcONa
Ph
O
N
N
Ar
HO
OH
N
Ph
NH2
NH
N
H
N
N
N
S
N
N
N
CH3
O
N
H2N
NH2
H2N
N
X
N
Ar
N
H
X
The utilization of arylhydrazononitriles (6-9) for synthesis of azoles is demonstrated. Thus,
arylazomalononitriles (6) reacted with hydroxylamine hydrochloride to afford isoxazol-5-imine (10),
amidoxime (12) and bis-amidoxime (13) derivatives depending upon both the reaction conditions and
molar ratio employed. 2-Thiazolyl-2-arylhydrazononitriles (7) and cyanoformazans (8) gave 1,2,3-triazole
derivatives (15) and (17) respectively upon treatment with hydroxylamine hydrochloride and concomitant
loss of water molecule. Formation of novel 1,2,4-triazin-5(4H)-one derivatives (21) has efficiently been
carried out by treatment of amidoximes (18) with acetic anhydride in acetic acid.
J. Heterocyclic Chem., 45, 975 (2008).
RESULTS AND DISCUSSION
DMF in presence of sodium acetate to yield 1,2,3-triazoles 3a-
g
(Scheme 1), treatment of (1h-k) [7] under the same
conditions
Arylhydrazononitriles are versatile reagents that have
already been extensively utilized as precursors to
polyfunctional substituted heteroaromatics [1-4]. Recently it
has been found that whereas the arylhydrazononitriles (1a-g)
[5,6] reacted with hydroxylamine hydrochloride in refluxing
afforded 1,2,4-triazol-5-amine 4h-k. Amidoximes are isolable
intermediates in these reactions. Amidoxime 2a has
been
reported earlier [8] to be cyclized into aminoisoxazole 5a
when treated with concentrated sulphuric acid (cf. Scheme 1).
Scheme 1
NH2
R
N
N
OH
N
N
Ar
R
CN
3a-g
R
DMF
NH2OH.HCl
NH2
Ar
R
Ar
N
N
N
H
N
Anhyd. AcONa
N
H
N
NH2
N
Ar
1a-k
2a-k
4h-k
1-3a, R = C6H5CO ; Ar = C6H5
b, R = C6H5CO ; Ar = 4-ClC6H4
2a Conc H2SO4
c, R = benzimidazol-2-yl ; Ar = C6H5
d, R = benzimidazol-2-yl ; Ar = 4-ClC6H4
e, R = benzothiazol-2-yl ; Ar = C6H5
f, R = benzothiazol-2-yl ; Ar = 4-ClC6H4
g, R = CH3CO ; Ar = C6H5
1h, 2h, 4h, R = 4-NO2C6H4 ; Ar = C6H5
1j, 2j, 4j, R = C6H5 ; Ar = 4-NO2C6H4
1k, 2k, 4k, R = C6H5 ; Ar = 4-CH3C6H4
Ph
NH2
N
N
N
Ph
O
5a

976
S. M. Riyadh, H. M. Al-Matar and M. H. Elnagdi
Vol 45
It became quite clear that, the nature of end products of
Scheme 3). Moreover, HMBC-15N NMR revealed that
aromatic protons at ꢀ 8.02 ppm have two cross peaks with
nitrogen atoms resonating ꢀ 245 and 305 ppm for sp2 (N1,
N3), while compound 16 should show only one cross
peak at higher field for sp2 (N1).
these simple reactions is dependant on both nature of
substituent (R) in 1 as well as the pH of the cyclization
reaction. It occurred to us of value to investigate further
these reactions with the hope of arriving at firm
conclusions concerning anticipated reaction products. In
the present article we report on the behavior of the
arylhydrazononitriles 6-9 towards hydroxylamine
hydrochloride and then rationalize for previous
discrepancies.
Scheme 3
Ph
N
NH2
Ph
Ph
N
S
N
NH2
N
OH
Pip/ DMF
N
N
CN
N
S
S
NH2OH.HCl
N
15a-b Ar
N
Ph
NH
Ar
NH
Ar
Ph
EtOH/ AcONa
Ar
N
N
CN
N
NC
CN
Ph
CN
N
7a-b
14a-b
7a, 14-16a; Ar = C6H5
7b, 14-16b; Ar = 4-ClC6H4
CN
N
Ar
Ar
N
N
N
S
S
N
H
NH
Ar
N
H
N
Ar
N
NH2
N
N
H
16a-b
Ar
6
7
8
9
Analogously, cyanoformazans 8a-c reacted with
hydroxylamine hydrochloride in ethanolic sodium acetate
to afford directly 1,2,3-triazoles 17a-c (Scheme 4).
Thus, reacting 6a-c with hydroxylamine hydrochloride
under reflux for 8 hours in DMF solution afforded the
corresponding 3-aminoisoxazol-5-imines 10a-c. We could
not trace any formation of the 1,2,3-triazoles 11a-c;
clearly deviating from behavior of 1a-g (Scheme 2). On
the other hand, refluxing of hydrazononitrile 6c with
hydroxylamine hydrochloride (1:1) in ethanolic sodium
acetate afforded the amidoxime 12c. Reaction of 6a-c
with excess hydroxylamine (1:2) furnished the
corresponding bis-amidoximes 13a-c (cf. Scheme 2).
Scheme 4
NH2
Ar
N N
Ar
N N
CN
NH2OH.HCl
N
N
N
EtOH/ AcONa
NH
Ar
N
Ar
17a-c
8a-c
8a, 17a; Ar = 4-ClC6H4
8b, 17b; Ar = 4-NO2C6H4
8c, 17c; Ar = 4-CH3OC6H4
Scheme 2
In an attempt to affect cyclization of amidoxime 18a by
action of acetic anhydride in the presence of acetic acid a
product of molecular formula C16H12N4O3 was obtained.
This was formulated as 21a and is assumed to be formed
via initial acylation of 18a into 19a that then cyclized to
20a. Hydrolysis of the oxime moiety in the latter afforded
a novel 1,2,4-triazinone derivative 21a. Absence of NH
NH2
NC
N
N
OH
N
Ar
N
NC
(1:1)
CN
NC
NH2OH.HCl
DMF/ Pip
NH2OH.HCl
NH2
Ar
11a-c
Ar
N
N
H
N
EtOH/ AcONa
N
H
Ar
NH
N
H
N
6a-c
12c
1
O
N
proton in H NMR enabled ruling out structure 22 (cf.
H2N
NH OH.HCl
(1:2)
2
EtOH/ AcONa
Scheme 5). Similar treatment of 18b-c under the same
conditions gave 21b-c. Although oximes are not readily
hydrolysable, the situation with compound 20 is different.
As initially compound 20 tautomerizes into nitroso
10a-c
HO
OH
N
N
H2N
NH2
Ar
6a, 10-13a; Ar = C6H5
6b, 10-13b; Ar = 4-CH3C6H4
6c, 10-13c; Ar = 4-ClC6H4
N
N
H
Scheme 5
13a-c
9a-c
OH
N
NHCOCH3
The reactions of 7a-b with hydroxylamine
O
N
Ph
OH
N
Ph
H2O
Ph
hydrochloride in ethanolic sodium acetate have afforded
as recently reported [5] amidoximes 14a-b. Cyclization of
the latter in DMF and piperidine gave 1,2,3-triazoles 15a-
b (Scheme 3). Possible rearrangement into isomeric 1,2,4-
triazoles 16a-b was excluded based on NOE difference
experiments. Thus, irradiation of NH2 at ꢀ 5.37 ppm did
not enhance aryl protons and vice versa irradiation o-aryl
protons at ꢀ 7.91 ppm did not enhance amino protons (cf.
N
NH2
N
N
N
N
NH
Ar
Ph
CH3
N
N
CH3
OH
AcOH/ Ac2O
Ar
Ar
N
19a-c
NHCOCH3
NH
Ar
20a-c
21a-c
Reflux 4h
Ph
Compd. no.
Ar
18a-c
N
N
N
4-NO2C6H4
4-ClC6H4
4-CH3C6H4
9a, 18-22a
9b, 18-22b
9c, 18-22c
Ar
22a-c

Jul-Aug 2008
Studies with 2-Arylhydrazononitriles: Further Investigations on Reactivity
977
(78%), mp 210 °C; IR (KBr) ꢀ = 3474, 3201 (NH2), 3301 (NH),
3148 (NH), 1617 (C=N) cm-1; 1H NMR (DMSO-d6) ꢀ = 6.00 (s,
2H, NH2), 7.61 (s, 1H, NH), 7.62 (d, 2H, J = 8 Hz), 7.89 (s, 1H,
NH), 7.92 (d, 2H, J = 8 Hz); 13C NMR ꢀ = 120.45, 127.96,
130.57, 132.45, 138.54, 155.37, 164.57; MS, m/z (%) 238
(M++1, 40), 237 (M+, 100), 195 (45), 126 (40), 111 (20). Anal.
Calcd. for C9H8ClN5O: C, 45.49; H, 3.39; N, 29.47. Found: C,
45.28; H, 3.38; N, 29.17.
Synthesis of acetamidines (12), (14) and propanediimi-
damides (13). To a solution of arylazomalononitrile (10 mmol)
in ethanol (95%, 40 mL) were added hydroxylamine
hydrochloride (0.7 g, 10 mmol) (or 1.4 g, 20 mmol) and
anhydrous sodium acetate (1 g). The mixture was refluxed for 3
hours and the solvent was removed under vacuum. The residue
was diluted with water. The solid precipitate was collected by
filtration and recrystallized from appropriate solvent.
tautomer it will undergo ipso-substitution with acetoxy
group. The formed acetoxy compound is hydrolysed
readily upon water treatment. Ipso substitution is well
known [9].
In conclusion of this work and previous one [5-7] it
may be suggested that amidoximes are prime products of
reacting functionally substituted arylhydrazononitriles
with hydroxylamine hydrochloride. Cyclization of the
products can afford either 1,2,3-triazoles, 1,2,4-triazoles
or isoxazoles depending on the nature of substituents and
applied cyclization conditions. The acyl, aroyl, azolyl and
other substituents that can stabilize a 1,2,3-triazole ring by
effective delocalization of nitrogen lone pair would
cyclize into 1,2,3-triazoles, in the absence of this effect or
if the reactivity of substituents is sufficient to allow for
isoxazole formation, the latter would be formed. In
2-Cyano-2-(4-chlorophenylhydrazono)-N-hydroxyaceta-
midine (12c). This compound was obtained in 1.89 g (80%), mp
271 °C [MeOH]; IR (KBr) ꢀ = 3498 (OH), 3441, 3175 (NH2),
absence of both effects
a
rare Beckmann like
1
3336 (NH), 2214 (CN), 1603 (C=N) cm-1; H NMR (DMSO-d6)
rearrangement leading to 1,2,4-triazoles would occur.
ꢀ = 5.67 (s, 2H, NH2), 7.38 (d, 2H, J = 8 Hz), 7.50 (s, 1H, NH),
7.68 (d, 2H, J = 8 Hz), 11.79 (s, 1H, OH); MS, m/z (%) 239
(M++2, 40), 238 (M++1, 20), 237 (M+, 100), 125 (80), 111 (50).
Anal. Calcd. for C9H8ClN5O: C, 45.49; H, 3.39; N, 29.47.
Found: C, 45.23; H, 3.49; N, 29.29.
EXPERIMENTAL
Melting points were recorded on Gallenkamp apparatus and
are uncorrected. Infrared spectra (KBr) were determined on a
Perkin-Elmer 2000 FT-IR system. 1H NMR was determined on a
Bruker DPX 400 MHz superconducting spectrometer in CDCl3
and DMSO-d6 as solvents and using TMS as internal standard.
Mass spectra were measured on MS 30 and MS 9 (AEI)
spectrometers, with EI 70 eV. Elemental analyses were
measured by means of LECO CHNS-932 Elemental Analyzer.
Arylhydrazononitriles (6) [10], (7) [11], (8) [4] and (9) [7] were
prepared as previously described.
Synthesis of 5-imino-4-arylhydrazono-4,5-dihydroisoxazol-
3-ylamine (10a-c). To a stirred solution of arylazomalononitrile
(10 mmol) in DMF (50 mL) containing anhydrous piperidine (2
mL) was added hydroxylamine hydrochloride (0.7 g, 10 mmol).
The mixture was refluxed for 8 hours and poured into water. The
solid precipitate was collected by filtration and purified by long
column chromatography [eluent: hexane/AcOEt (3:1)]
N,N`-Dihydroxy-2-phenylhydrazonopropanediimidamide
(13a). This compound was obtained in 1.42 g (60%), mp 160 °C
[EtOH/H2O]; IR (KBr) ꢀ = 3462 (OH), 3344, 3230 (NH2), 3171
1
(NH), 1599 (C=N) cm-1; H NMR (DMSO-d6) ꢀ = 5.65 (s, 2H,
NH2), 6.90 (s, 2H, NH2), 7.21-7.36 (m, 5H, Ar-H), 9.95 (s, 1H,
OH), 10.19 (s, 1H, NH), 12.90 (s, 1H, OH); 13C NMR ꢀ =
120.37, 126.38, 128.15, 143.18, 144.75, 164.31, 164.56; MS,
m/z (%) 236 (M+, 100), 219 (20), 177 (40), 77 (50). Anal. Calcd.
for C9H12N6O2: C, 45.76; H, 5.12; N, 35.58. Found: C, 45.57; H,
5.04; N, 35.77.
N,N'-Dihydroxy-2-(4-methylphenylhydrazono)-propane-
diimidamide (13b). This compound was obtained in 1.50 g
(62%), mp 140 °C [MeOH/H2O]; IR (KBr) ꢀ = 3463 (OH),
3342, 3228 (NH2), 3161 (NH), 1609 (C=N) cm-1; 1H NMR
(DMSO-d6) ꢀ = 2.24 (s, 3H, Ar-CH3), 5.62 (s, 2H, NH2), 6.65 (s,
2H, NH2), 7.11-7.22 (m, 4H, Ar-H), 9.91 (s, 1H, OH), 10.14 (s,
1H, NH), 12.90 (s, 1H, OH); 13C NMR ꢀ = 23.55 (Ar-CH3),
118.45, 124.18, 125.31, 142.88, 143.57, 164.08, 164.29; MS,
m/z (%) 250 (M+, 100), 233 (40), 191 (25), 91 (20). Anal. Calcd.
for C10H14N6O2: C, 47.99; H, 5.64; N, 33.58. Found: C, 47.83; H,
5.42; N, 33.39.
5-Imino-4-phenylhydrazono-4,5-dihydro-isoxazol-3-yl-
amine (10a). This compound was obtained in 1.42 g (70%), mp
145 °C; IR (KBr) ꢀ = 3434, 3271 (NH2), 3317 (NH), 3166 (NH),
1
1601 (C=N) cm-1; H NMR (DMSO-d6) ꢀ = 5.94 (s, 2H, NH2),
7.34 (s, 1H, NH), 7.34-7.55 (m, 3H, Ar-H), 7.78 (s, 1H, NH),
7.91 (d, 2H, Ar-H); 13C NMR ꢀ = 118.67, 127.89, 128.05,
130.59, 139.98, 155.41, 164.50; MS, m/z (%) 203 (M+, 100), 160
(80), 92 (40), 77 (10). Anal. Calcd. for C9H9N5O: C, 53.20; H,
4.46; N, 34.47. Found: C, 53.40; H, 4.51; N, 34.26.
5-Imino-4-(4-methylphenylhydrazono)-4,5-dihydroisoxa-
zol-3-ylamine (10b). This compound was obtained in 1.56 g
(72%), mp 195 °C; IR (KBr) ꢀ = 3455, 3224 (NH2), 3357 (NH),
3166 (NH), 1617 (C=N) cm-1; 1H NMR (DMSO-d6) ꢀ = 2.34 (s,
3H, Ar-CH3), 5.90 (s, 2H, NH2), 7.32 (d, 2H, J = 8 Hz), 7.45 (s,
1H, NH), 7.73 (s, 1H, NH), 7.81 (d, 2H, J = 8 Hz); 13C NMR ꢀ =
21.58 (Ar-CH3), 118.79, 127.14, 131.00, 137.62, 138.02, 155.14,
164.78; MS, m/z (%) 217 (M+, 100), 174 (55), 106 (25), 91 (40).
Anal. Calcd. for C10H11N5O: C, 55.29; H, 5.10; N, 32.24. Found:
C, 55.21; H, 4.90; N, 32.01.
N,N'-Dihydroxy-2-(4-chlorophenylhydrazono)-propane-
diimidamide (13c). This compound was obtained in 1.62 g
(60%), mp 188 °C [MeOH]; IR (KBr) ꢀ = 3471 (OH), 3348,
3241 (NH2), 3183 (NH), 1611 (C=N) cm-1; 1H NMR (DMSO-d6)
ꢀ = 5.68 (s, 2H, NH2), 6.81 (s, 2H, NH2), 7.23-7.68 (m, 4H, Ar-
H), 9.98 (s, 1H, OH), 10.33 (s, 1H, NH), 13.21 (s, 1H, OH); 13
C
NMR ꢀ = 121.18, 126.91, 128.88, 144.16, 146.23, 164.98,
165.36; MS, m/z (%) 272 (M++2, 30), 271 (M++1, 10), 270 (M+,
100), 253 (20), 211 (35), 111 (40). Anal. Calcd. for
C9H11ClN6O2: C, 39.94; H, 4.10; N, 31.05. Found: C, 39.83; H,
4.13; N, 31.23.
N-Hydroxy-2-(phenylhydrazono)-2-(4-phenylthiazol-2-yl)-
acetamidine (14a). This compound was obtained in 2.02 g
(60%), mp 193 °C [MeOH]; IR (KBr) ꢀ = 3434 (OH), 3394,
3241 (NH2), 3104 (NH), 1600 (C=N) cm-1; 1H NMR (DMSO-d6)
ꢀ = 5.81 (s, 2H, NH2), 7.01-8.08 (m, 10H, Ar-H), 8.31 (s, 1H,
5-Imino-4-(4-chlorophenylhydrazono)-4,5-dihydroisox-
azol-3-ylamine (10c). This compound was obtained in 1.85 g

978
S. M. Riyadh, H. M. Al-Matar and M. H. Elnagdi
Vol 45
thiazole-H), 10.11 (s, 1H, NH), 14.28 (s, 1H, OH); MS, m/z (%)
337 (M+, 100), 319 (50), 187 (25), 134 (20), 77 (20). Anal.
Calcd. for C17H15N5OS: C, 60.52; H, 4.48; N, 20.76; S, 9.50.
Found: C, 60.64; H, 4.57; N, 20.66; S, 9.63.
(62%), mp 184 °C; IR (KBr) ꢁ = 3453, 3281 (NH2), 1601 (C=N)
1
cm-1; H NMR (DMSO-d6) ꢀ = 3.50 (s, 3H, Ar-CH3), 3.52 (s,
3H, Ar-CH3), 5.62 (s, 2H, NH2), 7.03 (d, 2H, J = 8 Hz), 7.05 (d,
2H, J = 8 Hz), 7.75 (d, 2H, J = 8 Hz), 7.77 (d, 2H, J = 8 Hz); 13
C
N-Hydroxy-2-(4-chlorophenylhydrazono)-2-(4-phenylthia-
zol-2-yl)-acetamidine (14b). This compound was obtained in
2.22 g (60%), mp 216 °C [MeOH]; IR (KBr) ꢀ = 3438 (OH),
3370, 3252 (NH2), 3116 (NH), 1602 (C=N) cm-1; 1H NMR
(DMSO-d6) ꢀ = 5.86 (s, 2H, NH2), 7.31-7.88 (m, 5H, Ar-H),
7.91 (d, 2H, J = 8 Hz), 8.41 (s, 1H, thiazole-H), 8.61 (d, 2H, J =
8 Hz), 10.31 (s, 1H, NH), 13.88 (s, 1H, OH); MS, m/z (%) 373
(M++2, 10), 372 (M++1, 30), 371 (M+, 100), 353 (40), 126 (20),
111 (50). Anal. Calcd. for C17H14ClN5OS: C, 54.91; H, 3.79; N,
18.83; S, 8.62. Found: C, 54.77; H, 3.59; N, 18.76; S, 8.53.
Synthesis of 1,2,3-triazol-4-amines (15a-b). A solution of
acetamidine 14 (1 mmol) in dry DMF (40 mL) and piperidine (2
mL) was refluxed for 4 hours, until the reaction was completed
(TLC). The mixture was treated with water and extracted by
chloroform. The organic layer was dried and concentrated. The
residue was purified by column chromatography [eluent:
hexane/AcOEt (3:1)].
NMR ꢀ = 55.52, 56.21, 118.62, 119.13, 121.55, 122.18, 128.51,
129.21, 139.77, 141.56, 152.56, 153.13; MS, m/z (%) 324 (M+,
100), 135 (20), 107 (60). Anal. Calcd. for C16H16N6O2: C, 59.25;
H, 4.97; N, 25.91. Found: C, 59.44; H, 5.01; N, 25.83.
Synthesis of 1,2,4-triazinones (21a-c). To a solution of
acetamidine 18 (1 mmol) in acetic acid (15 mL) was added
acetic anhydride (1 mmol). The reaction mixture was heated
under reflux for 4 hours, cooled to room temperature, quenched
by the addition of H2O (20 mL), and extracted with chloroform
(3 x 25 mL). The combined organic extracts were dried over
MgSO4, and evaporated under reduced pressure. The residue
was purified by column chromatography [eluent: hexane/AcOEt
(3:1)].
3-Methyl-2-(4-nitrophenyl)-6-phenyl-1,2,4-triazin-5(2H)-
one (21a). This compound was obtained in 0.22 g (70%), mp
1
180 °C; IR (KBr) ꢁ = 1656 (CO), 1596 (C=N) cm-1; H NMR
(DMSO-d6) ꢀ = 2.29 (s, 3H, CH3), 7.45-7.53 (m, 3H, Ar-H),
8.04 (d, 2H, J = 8 Hz), 8.07 (m, 2H, Ar-H), 8.47 (d, 2H, J = 8
Hz); 13C NMR ꢀ = 23.99 (CH3), 126.03, 129.20, 129.26, 129.68,
131.51, 132.99, 147.46, 147.80, 148.73, 161.29 (Ar-C), 161.78
(CO); MS, m/z (%) 308 (M+, 20), 205 (100), 163 (60), 77 (15).
Anal. Calcd. for C16H12N4O3: C, 62.33; H, 3.92; N, 18.17.
Found: C, 62.41; H, 3.81; N, 18.26.
2-Phenyl-5-(4-phenylthiazol-2-yl)-2H-1,2,3-triazol-4-amine
(15a). This compound was obtained in 0.21 g (65%), mp 164
°C; IR (KBr) ꢁ = 3407, 3271 (NH2), 1603 (C=N) cm-1; 1H NMR
(DMSO-d6) ꢀ = 5.33 (s, 2H, NH2), 7.35-8.12 (m, 10H, Ar-H),
8.21 (s, 1H, thiazole-H); 13C NMR ꢀ = 114.61, 118.43, 127.28,
127.87, 129.38, 129.72, 129.89, 130.72, 134.52, 139.87, 152.45,
155.79, 159.44; MS, m/z (%) 319 (M+, 100), 277 (50), 187 (25),
134 (20), 77 (50). Anal. Calcd. for C17H13N5S: C, 63.93; H, 4.10;
N, 21.93; S, 10.04. Found: C, 63.84; H, 4.21; N, 21.81; S, 9.93.
2-(4-Chlorophenyl)-5-(4-phenylthiazol-2-yl)-2H-1,2,3-tria-
zol-4-amine (15b). This compound was obtained in 0.23 g
(68%), mp 181 °C; IR (KBr) ꢁ = 3410, 3288 (NH2), 1600 (C=N)
3-Methyl-2-(4-chlorophenyl)-6-phenyl-1,2,4-triazin-5(2H)-
one (21b). This compound was obtained in 0.19 g (65%), mp
1
190 °C; IR (KBr) ꢁ = 1662 (CO), 1601 (C=N) cm-1; H NMR
(CDCl3) ꢀ = 2.39 (s, 3H, CH3), 7.45-7.52 (m, 3H, Ar-H), 7.71 (d,
2H, J = 8 Hz), 7.72 (m, 2H, Ar-H), 8.09 (d, 2H, J = 8 Hz); 13C
NMR ꢀ = 23.15 (CH3), 125.53, 128.58, 128.96, 129.88, 130.41,
133.09, 144.51, 145.71, 148.43, 161.89 (Ar-C), 162.57 (CO);
MS, m/z (%) 297 (M+, 30), 194 (100), 151 (40), 77 (25). Anal.
Calcd. for C16H12ClN3O: C, 64.54; H, 4.06; N, 14.11. Found: C,
64.71; H, 3.81; N, 14.28.
1
cm-1; H NMR (DMSO-d6) ꢀ = 5.36 (s, 2H, NH2), 7.35-7.92 (m,
5H, Ar-H), 8.02 (d, 2H, J = 8 Hz), 8.31 (s, 1H, thiazole-H), 8.51
(d, 2H, J = 8 Hz); 13C NMR ꢀ = 115.11, 118.13, 127.48, 128.17,
129.83, 130.33, 130.89, 131.52, 135.62, 139.21, 151.23, 145.85,
158.65; MS, m/z (%) 355 (M++2, 10), 354 (M++1, 30), 353 (M+,
100), 126 (20), 111 (50). Anal. Calcd. for C17H12ClN5S: C,
57.71; H, 3.42; N, 19.79; S, 9.06. Found: C, 57.64; H, 3.51; N,
19.66; S, 8.93.
2-(4-Chlorophenyl)-5-(4-chlorophenylazo)-2H-1,2,3-tria-
zol-4-amine (17a). This compound was obtained in 0.20 g
(61%), mp 192 °C; IR (KBr) ꢁ = 3448, 3281 (NH2), 1635 (C=N)
cm-1; 1H NMR (DMSO-d6) ꢀ = 5.72 (s, 2H, NH2), 7.51 (d, 2H, J
= 8 Hz), 7.62 (d, 2H, J = 8 Hz), 7.79 (d, 2H, J = 8 Hz), 7.91 (d,
2H, J = 8 Hz); 13C NMR ꢀ = 127.15, 127.67, 129.23, 129.84,
130.51, 131.12, 134.62, 135.21, 139.11, 141.51; MS, m/z (%)
335 (M++2, 30), 334 (M++1, 50), 333 (M+, 80), 139 (40), 111
(100). Anal. Calcd. for C14H10Cl2N6: C, 50.47; H, 3.03; N, 25.22.
Found: C, 50.64; H, 3.11; N, 25.33.
3-Methyl-2-(4-methylphenyl)-6-phenyl-1,2,4-triazin-5(2H)-
one (21c). This compound was obtained in 0.17 g (60%), mp
1
235 °C; IR (KBr) ꢁ = 1660 (CO), 1598 (C=N) cm-1; H NMR
(CDCl3) ꢀ = 2.29 (s, 3H, CH3), 2.53 (s, 3H, Ar-CH3), 7.04 (d,
2H, J = 8 Hz), 7.42-7.52 (m, 5H, Ar-H), 8.21 (d, 2H, J = 8 Hz);
13C NMR ꢀ = 22.59 (Ar-CH3), 23.68 (CH3), 121.83, 125.11,
128.21, 128.71, 130.67, 131.65, 143.79, 144.80, 147.70, 161.74
(Ar-C), 163.13 (CO); MS, m/z (%) 277 (M+, 30), 174 (100), 133
(80), 77 (30). Anal. Calcd. for C17H15N3O: C, 73.63; H, 5.45; N,
15.15. Found: C, 73.41; H, 5.61; N, 15.28.
Acknowledgement. The support of this work was received
from University of Kuwait through research grant (SC04/06)
and the facilities of Analab/SAF through research grant
(GC01/01) and (GS03/01) are gratefully acknowledged.
2-(4-Nitrophenyl)-5-(4-nitrophenylazo)-2H-1,2,3-triazol-
4-amine (17b). This compound was obtained in 0.22 g (60%),
mp 205 °C; IR (KBr) ꢁ = 3451, 3292 (NH2), 1625 (C=N) cm-1;
1H NMR (DMSO-d6) ꢀ = 5.82 (s, 2H, NH2), 7.68 (d, 2H, J = 8
Hz), 7.82 (d, 2H, J = 8 Hz), 8.82 (d, 2H, J = 8 Hz), 8.31 (d, 2H,
J = 8 Hz); 13C NMR ꢀ = 127.25, 127.88, 129.11, 129.94,
139.43, 141.47, 142.23, 143.16, 147.11, 147.93; MS, m/z (%)
354 (M+, 20), 176 (40), 122 (100). Anal. Calcd. for C14H10N8O4:
C, 47.46; H, 2.85; N, 31.63. Found: C, 47.64; H, 3.01; N, 31.53.
2-(4-Methoxyphenyl)-5-(4-methoxyphenylazo)-2H-1,2,3-
triazol-4-amine (17c). This compound was obtained in 0.20 g
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Studies with 2-Arylhydrazononitriles: Further Investigations on Reactivity
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