Synthesis of some symmetrical novel bis-thiosemicarbazides, 1,2,4-triazoles, 1,3,4-thiadiazoles, and their derivatives

Article abstract of DOI:10.1080/10426507.2010.480949

Synthesis of some novel bis-1,2,4-triazoles 5a-c and 1,3,4-thiadiazoles 6a-c bearing a pyridyl unit using 4-(1,4-phenylene)bis-1-(x-picolinoyl)- thiosemicarbazide (x = 2,3,4) in an acidic and alkaline solution, respectively, is reported. The S-alkylation

Full text of DOI:10.1080/10426507.2010.480949

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Synthesis of Some Symmetrical
Novel Bis-thiosemicarbazides, 1,2,4-
Triazoles, 1,3,4-Thiadiazoles, and Their
Derivatives
A. Mobinikhaledi a , N. Foroughifar a , M. Kalhor a , S. Ebrahimi a &
M. A. Bodaghi Fard a
a Department of Chemistry , Arak University , Arak, Iran
Published online: 13 Jan 2011.
To cite this article: A. Mobinikhaledi , N. Foroughifar , M. Kalhor , S. Ebrahimi & M. A. Bodaghi
Fard (2010) Synthesis of Some Symmetrical Novel Bis-thiosemicarbazides, 1,2,4-Triazoles, 1,3,4-
Thiadiazoles, and Their Derivatives, Phosphorus, Sulfur, and Silicon and the Related Elements, 186:1,
67-73, DOI: 10.1080/10426507.2010.480949
To link to this article: http://dx.doi.org/10.1080/10426507.2010.480949
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Phosphorus, Sulfur, and Silicon, 186:67–73, 2011
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2010.480949
SYNTHESIS OF SOME SYMMETRICAL NOVEL
BIS-THIOSEMICARBAZIDES, 1,2,4-TRIAZOLES,
1,3,4-THIADIAZOLES, AND THEIR DERIVATIVES
A. Mobinikhaledi, N. Foroughifar, M. Kalhor, S. Ebrahimi,
and M. A. Bodaghi Fard
Department of Chemistry, Arak University, Arak, Iran
GRAPHICAL ABSTRACT
O
Ar
Ar
NHCSNHNHC
H
N
S
N
S
N
N
N
Ar
N
N
N
N
N
N
N
H
Ar
Ar
O
SR
RS
NHCSNHNHC
Ar
Abstract Synthesis of some novel bis-1,2,4-triazoles 5a–c and 1,3,4-thiadiazoles 6a–c bearing
a pyridyl unit using 4-(1,4-phenylene)bis-1-(x-picolinoyl)-thiosemicarbazide (x = 2,3,4) in an
acidic and alkaline solution, respectively, is reported. The S-alkylation of symmetrical triazole
derivatives 7a–c and 8a–c is also reported. The structures of the synthesized compounds result
from the IR and NMR spectroscopic data.
Keywords Thiadiazole; thiosemicarbazide; triazole
INTRODUCTION
It is well known that thiosemicarbazide derivatives exhibit interesting biological prop-
erties such as antitubercular,1 antidepressant,2 anti-inflammatory, and analgesic activity.3
In addition, 1,2,4-triazoles4–6 or thiadiazoles7–16 and pyridines17 have attracted the atten-
tion of chemists due to attractive biological activities. On the other hand, incorporating
the pyridine ring into active compounds may improve their biological or physiological
activities.18 These heterocyclic systems, especially a combination of these units, 1,2,4-
triazoles, thiadiazoles, and pyridine, could result in a large variety of structures and biolog-
ical activities. Several heterocyclic compounds containing a thiadiazole or triazole moiety
have been reported.4–16 However, the synthesis of novel heterocyclic systems containing a
bis(thiadiazole) or bis(triazole) system as well as bis(thiosemicarbazide) derivatives is still
a challenge.
As part of our ongoing studies on the synthesis of heterocycles,19,20 and also due to
versatile biological properties of thiadiazole and triazole derivatives, we report the synthesis
of some novel symmetrical bis(thiosemicarbazides), 1,3,4-thiadiazoles, and 1,2,4-triazoles.
Received 18 March 2010; accepted 19 March 2010.
Address correspondence to A. Mobinikhaledi, Department of Chemistry, Arak University, Arak 38156-879,
Iran. E-mail: akbar mobini@yahoo.com
67

68
A. MOBINIKHALEDI ET AL.
RESULTS AND DISCUSSION
The synthesis of the title compounds is illustrated in Scheme 1. The required pyri-
dine carboxylic acid hydrazides 2a–c were prepared via reaction of the appropriate pyridine
carboxylic acid with hydrazine according to the literature.21 The preparation of thiosemi-
carbazides 3a–c was achieved by the reaction of the corresponding substituted hydrazides
with 1,4-phenylenediisothiocyanate 1. Thiosemicarbazide derivatives 3a–c underwent an
intramolecular cyclization under basic or acidic conditions to produce bis(1,2,4-triazoles)
5a–c and bis(1,3,4-thiadiazoles) 6a–c in high yields (Table 1). The reaction yields for 5c
and 6c are higher than other respective isomers, which may be attributed to the stereoelec-
tronic effects of the nitrogen atom of the pyridine ring and also to the more symmetrical
structure of these products. The corresponding bis(1,2,4-triazolate) salts 4a–c were further
converted to the related symmetrically S-alkylated bis(1,2,4-triazole) derivatives 7a–c and
8a–c, when treated separately with methyl iodide or ethyl 2-chloro acetate.
The IR spectra of thiosemicarbazides 3a–c showed characteristic absorption at
1149–1157, 1676–1683, and 3128–3493 cm−1 for the C S, C O, and NH stretching
vibrations, respectively. 1H NMR spectra of 3a–c showed singlets at 9.73–10.81 ppm due
to the resonance of NH CS NH and CO NH protons, which disappeared upon D2O
addition. The 13C NMR spectrum of compound 3a showed nine signals, including a signal
at 164 ppm for the >C S and a signal at 180 ppm for the carbonyl carbon atoms.
The bis-triazole-3-thiols 5a–c were obtained by refluxing the corresponding
1
bis(thiosemicarbazides) in 4N NaOH solution, followed by acidification. The H NMR
spectra of compounds 5a–c showed singlets at 14.28–14.40 ppm attributed to the resonance
of the SH protons, which disappeared upon D2O addition. In the 13C NMR spectra of
compounds 5a–c, the appearance of signals at the region between 169.0–169.4 ppm
O
O
NCS
SCN
NCSNHNHC
NHCSNHNHC
Ar
Ar
1
EtOH
aqueos NaOH
+
O
O
Ar
CONHNH2
NCSNHNHC
NHCSNHNHC
2a-c
Ar
Ar
3a-c
H+
Ar
Ar
H
OH
HO
N
H
N
N
H
N
N
S
N
S
N
N
N
N
Ar
Ar
N
-2H2O
N
H
N
N
Ar
Ar
SNa
N
NaS
N
N
6a-c
N
HCl
RX
SNa
NaS
Acetone/H O
2
Ar
Ar
4a-c
Ar
Ar
N
N
N
N
N
N
N
N
N
N
N
N
Ar = 2-pyridyl, 3-pyridyl, 4-pyridyl
SH
HS
SR
RS
R = -Me, -CH2COOEt
5a-c
7a-c
8a-c
Scheme 1 Synthesis of bis(thiosemicarbazides), 1,2,4-triazoles, and 1,3,4-thiadiazoles.

SOME SYMMETRICAL NOVEL BIS-THIOSEMICARBAZIDES
69
Table 1 Reaction time, melting point, and yield of compounds 3 through 8a–c
Compound
Time (h)
Mp (◦C)
Yield (%)a
3a
3b
3c
5a
5b
5c
6a
6b
6c
7a
7b
7c
8a
8b
8c
0.08
0.3
0.03
1.0
0.6
1.5
8.0
8.0
8.0
0.05
0.4
0.5
4.5
3.0
4.0
225–227
198–199
229
385–387
395–397
390–393
357–358
341
82
80
84
87
88
90
90
83
94
75
52
52
40
55
47
369–370
295
276–277
297–300
208–209
203–204
202
aIsolated yield.
attributed to the carbon resonance of the C N group in triazole rings is in support of the
expected thiol structures.
The IR spectra of 6a–c showed absorption bands at 3256–3265 cm−1 characteristic
1
for the NH group. Also in the H NMR spectra of all bis(1,3,4-thiadiazoles), the singlet
at 10.59–10.74 ppm was attributed to the resonance of the NH proton. S-Alkylated 1,2,4-
triazoles, 7a–c and 8a–c, were obtained by refluxing the appropriate triazole salts 4a–c with
methyl iodide and ethyl 2-chloroacetate in aqueous acetone, respectively. In the 1H NMR
spectra of 7a–c and 8a–c, the absence of the -SH resonance and the appearance of a singlet
in the aliphatic region, related to the resonance of the -SR group, supports the formation of
the alkylated products.
EXPERIMENTAL
All chemicals used were purchased from Merck or Fluka. Melting points were deter-
mined using an electrothermal digital apparatus and are uncorrected. Elemental analyses
were performed with an Elemental Analyzer (Elemental, Vario EL III) at Arak Univer-
sity. IR spectra were obtained with a galaxy series FT-IR 5000 spectrometer using KBr
discs. NMR spectra were recorded on a Bruker (300 MHz) spectrometer. Chemical shifts
(ppm) are referenced to tetramethylsilane (TMS) as an internal standard. Reactions were
monitored by thin layer chromatography.
Preparation of Bis(thiosemicarbazides) 3a–c: General Procedure
A solution of 1,4-phenylenediisothiocyanate (0.2 g, 1 mmol) in ethanol (30 mL) was
added to a solution of pyridyl acid hydrazide 2a–c (0.28 g, 2.0 mmol) in absolute ethanol
(15 mL) with stirring. The reaction mixture was refluxed for 2–30 min. The solution was
cooled to ambient temperature, and the precipitate was filtered to give the crude product,
which was then recrystallized from DMF:EtOH (15:1) to give pure 3a–c.

70
A. MOBINIKHALEDI ET AL.
4,4-(1,4-Phenylene)bis-1-(2-picolinoyl)-thiosemicarbazide (3a). IR (KBr):
ν = 1149 (C S), 1271, 1373 (C C), 1518, 1572 (C N), 1683 (C O), 3094 (C Harom),
1
3159, 3229, 3354 (N H) cm−1; H NMR (DMSO-d6): δ = 7.39 (s, 4H, C Hphenylene),
7.64 (m, 2H, C Hpyridyl), 8.02 (d, J = 9.5 Hz, 4H, C Hpyridy), 8.67 (d, J = 9.5 Hz, 2H,
C Hpyridy), 9.71 (s, 4H, NH CS NH), 10.70 (s, 2H, NH); 13C NMR (DMSO-d6): δ =
122.9, 125.3, 127.3, 136.4, 138.1, 148.9, 149.8, 164.1, 180.9; Ms: m/z 465 (5), 436 (7),
192 (30), 99 (35), 85 (100), 71 (90), 57 (83), 43(92); Anal. Calcd. for C20H18N8O2S2: C,
51.49; H, 3.89; N, 24.02; S, 13.75. Found: C, 51.76; H, 4.08; N, 23.96; S, 13.97%.
4,4-(1,4-Phenylene)bis-1-(3-picolinoyl)-thiosemicarbazide (3b). IR (KBr):
ν = 115 7 (C S), 1255, 1371 (C C), 1514, 1570 (C N), 1678 (C O), 3050 (C Harom),
3171, 3232, 3493 (N H) cm−1; 1H NMR (DMSO-d6): δ = 7.4 (s, 4H, C Hphenylene), 7.54
(t, J = 5.1 Hz, 2H, C Hpyridyl), 8.28 (d, J = 7.1 Hz, 2H, C Hpyridy), 8.75 (d, J = 6.8 Hz,
2H, C Hpyridy), 9.12 (s, 2H, C Hpyridy), 9.89 (s, 4H, NH CS NH), 10.81 (s, 2H, NH);
Anal. Calcd. for C20H18N8O2S2: C, 51.49; H, 3.89; N, 24.02; S, 13.75. Found: C, 51.26;
H, 3.67; N, 24.32; S, 13.47%.
4,4-(1,4-Phenylene)bis-1-(4-picolinoyl)-thiosemicarbazide (3c). IR (KBr):
ν = 1149 (C S), 1228, 1263 (C C), 1518, 1602 (C N), 1676 (C O), 3047 (C Harom),
3128, 3244 (N H) cm−1; 1H NMR (DMSO-d6): δ = 7.28 (s, 4H, C Hphenylene), 7.75 (d,
J = 4.8 Hz, 4H, C Hphenylene), 8.67 (d, J = 4.7 Hz, 4H, C Hpyridyl), 9.73 (s, 2H, CS NH),
9.76 (s, 2H, NH CS), 10.78 (s, 2H, CONH); Anal. Calcd. for C20H18N8O2S2: C, 51.49;
H, 3.89; N, 24.02; S, 13.75. Found: C, 51.43; H, 4.17; N, 24.23; S, 13.96%.
Preparation of 5,5-Substituted Bis-3-mercapto-1,2,4-triazoles 5a–c:
General Procedure
Bis(thiosemicarbazide) 3a–c (0.5g, 1 mmol) was added slowly to a solution of 4N
sodium hydroxide (10–15 mL). The reaction mixture was refluxed for the proper time
(Table 1) to give the corresponding salt, which was then filtered and washed with 1N
sodium hydroxide solution and water to give the intermediate compounds 4a–c. The filtrate
was refluxed for 1 h and after cooling to ambient temperature was acidified with 2N
hydrochloric acid. The precipitate was filtered and washed thoroughly with water (5 mL),
dried, and recrystallized from DMSO:H2O (6:0.5) to give the pure products.
4,4-(1,4-Phenylene)bis-5-(2-pyridyl)-1,2,4-triazole-3-thiol (5a). IR (KBr):
ν = 1280 (C S), 1336 (C C), 1604 (C N), 3050 (C Harom), 3117, 3188 (N H)
1
cm−1; H NMR (DMSO-d6): δ = 7.36 (s, 4H, C Hphenylene), 7.41 (q, J = 10.1 Hz, 2H,
C Hpyridyl), 7.79 (d, J = 7.9 Hz, 2H, C Hpyridyl), 7.89 (t, J = 7.7 Hz, 2H, C Hpyridyl), 8.33
(d, J = 4.6 Hz, 2H, C Hpyridyl), 14.28 (s, 2H, S H); 13C NMR (DMSO-d6): δ = 124.4,
125.5, 129.2, 135.6, 137.8, 145.4, 149.5, 150.0, 169.4; Anal. Calcd. for C20H14N8S2: C,
55.80; H, 3.28; N, 26.03; S, 14.90. Found: C, 55.70; H, 3.37; N, 26.33; S, 15.07%.
4,4-(1,4-Phenylene)bis-5-(3-pyridyl)-1,2,4-triazole-3-thiol (5b). IR (KBr):
ν = 1400, 1438 (C C), 1550, 1610 (C N), 2688 (SH), 3061 (C Harom) cm−1; 1H NMR
(DMSO-d6): δ = 7.42 (t, J = 6.7 Hz, 2H, C Hpyridyl), 7.50–7.57 (m, 6H, C Hpyridyl and
C Hphenylene), 8.56 (s, 2H, C Hpyridyl), 8.65 (t, J = 6.7 Hz, 2H, C Hpyridyl), 14.33 (s, 2H,
N H), The SH protons disappeared upon D2O addition; 13C NMR (DMSO-d6): δ = 122.5,
123.8, 130.4, 135.3, 136.1, 148.9, 149.2, 151.5, 169.0; Anal. Calcd. for C20H14N8S2: C,
55.80; H, 3.28; N, 26.03; S, 14.90. Found: C, 56.14; H, 3.34; N, 25.61; S, 14.59%.
4,4-(1,4-Phenylene)bis-5-(4-pyridyl)-1,2,4-triazole-3-thiol (5c). This com-
pound was obtained as light yellow precipitate. IR (KBr): ν = 1197 (C S), 1334, 1428

SOME SYMMETRICAL NOVEL BIS-THIOSEMICARBAZIDES
71
(C C), 1516, 1606 (C N), 3092 (C Harom), 3194 (N H) cm−1; 1H NMR (DMSO-d6):
δ = 7.23 (d, J = 4.6 Hz, 4H, C Hpyridyl), 7.58 (s, 4H, C Hphenylene), 8.58 (d, J = 4.7 Hz,
4H, C Hpyridyl), 14.43 (bs, 2H, S H); 13C NMR (DMSO-d6): δ = 122.6, 130.4, 133.6,
135.4, 148.9, 150.4, 169.4; Anal. Calcd. for C20H14N8S2: C, 55.80; H, 3.28; N, 26.03; S,
14.90. Found: C, 55.61; H, 3.18; N, 26.13; S, 14.70%.
Preparation of 2, 2-Substituted Bis-(pyridyl)-1,3,4-thiadiazoles 6a–c:
General Procedure
The thiosemicarbazides 3a–c (0.39 g, 0.6 mmol) were◦added slowly to concentrated
sulfuric acid (10–15 mL), which was stirred and kept at 0 C. The reaction mixture was
stirred at room temperature for 8 h. It was then poured into ice-water (50 g) and neutralized
with concentrated aqueous ammonia. The precipitate was filtered, washed with water
(15 mL), dried, and recrystallized from DMF:H2O (10:1) to give pure 6a–c.
2,2-(1,4-Phenylendiamine)bis-5-(2-pyridyl)-1,3,4-thiadiazole (6a). This
compound was obtained as a dark yellow precipitate. IR (KBr): ν = 1415, 1485 (C C),
1525, 1593 (C N), 3065 (C Harom), 3257 (N H) cm−1;1H NMR (DMSO-d6): δ = 7.49
(t, J = 6.8 Hz, 2H, C Hpyridyl), 7.68 (s, 4H, C Hphenylene), 7.97 (d, J = 7.7 Hz, 2H,
C Hpyridyl), 8.13 (d, J = 7.9 Hz, 2H, C Hpyridyl), 8.63 (d, J = 4.4 Hz, 2H, C Hpyridyl),
10.60 (s, 2H, N H); Anal. Calcd. for C20H14N8S2: C, 55.80; H, 3.28; N, 26.03; S, 14.90.
Found: C, 56.05; H, 3.54; N, 25.76; S, 14.63%.
2,2-(1,4-Phenylendiamine)bis-5-(3-pyridyl)-1,3,4-thiadiazole (6b). This
compound was obtained as a dark yellow precipitate. IR (KBr): ν = 1236, 1415 (C C),
1510, 1608 (C N), 3025 (C Harom), 3169, 3256 (N H) cm−1.1H NMR (DMSO-d6): δ =
7.51 (t, J = 7.4 Hz, 2H, C Hpyridyl), 7.66 (s, 4H, C Hphenylene), 8.19 (d, J = 7.6 Hz, 2H,
C Hpyridyl), 8.63 (d, J = 4.2 Hz, 2H, C Hpyridyl), 9.02 (s, 2H, C Hpyridyl), 10.59 (s, 2H,
N H). 13C NMR (DMSO-d6): δ = 119.1, 124.6, 127.1, 134.3, 135.8, 147.7, 151.1, 154.6,
165.2; Anal. Calcd. for C20H14N8S2: C, 55.80; H, 3.28; N, 26.03; S, 14.90. Found: C,
55.52; H, 3.56; N, 25.77; S, 14.58%.
2,2-(1,4-Phenylendiamine)bis-5-(4-pyridyl)-1,3,4-thiadiazole
(6c). This
compound was obtained as a dark yellow precipitate. IR (KBr): ν = 1415 (C C), 1491,
1601 (C N), 3053 (C Harom), 3265 (N H) cm−1;1H NMR (DMSO-d6): δ = 7.69 (s, 4H,
C Hphenylene), 7.81 (d, J = 4.6 Hz, 4H, C Hpyridyl), 8.70 (d, J = 3.2 Hz, 4H, C Hpyridyl),
10.74 (s, 2H, N H); Anal. Calcd. for C20H14N8S2: C, 55.80; H, 3.28; N, 26.03; S, 14.90.
Found: C, 54.52; H, 3.39; N, 25.68; S, 14.59%.
Preparation of (3-Methylthio)-1,2,4-triazoles 7a–c: General Procedure
A solution of the triazole salt 4a–c (0.1 g, 0.2 mmol) and methyl iodide (0.025 mL, 0.4
mmol) in a mixture of acetone and water (20–30 mL, 3:2), was refluxed for the proper time
(Table 1). The solution was cooled to ambient temperature and filtered to give compound
7a–c.
4,4-(1,4-Phenylene)bis-[(3-methylthio)-5-(2-pyridyl)-1,2,4-triazole] (7a).
IR (KBr): ν = 704 (C S C), 1402, 1444 (C C), 1518, 1585 (C N), 2935 (CH3), 3072
(C Harom) cm−1.;1H NMR (DMSO-d6): δ = 2.65 (s, 6H, CH3), 7.42 (q, J = 7.3 Hz,
2H, C Hpyridyl), 7.49 (s, 4H, C Hphenylene), 7.94 (d, J = 7.6 Hz, 2H, C Hpyridyl), 8.02
(d, J = 7.4 Hz, 2H, C Hpyridyl), 8.30 (d, J = 4.6 Hz, 2H, C Hpyridyl); Anal. Calcd. for
C22H18N8S2: C, 57.62; H, 3.96; N, 24.44; S, 13.99. Found: C, 57.35; H, 4.21; N, 24.58; S,
13.78%.

72
A. MOBINIKHALEDI ET AL.
4, 4-(1,4-Phenylene)bis-[(3-methylthio)-5-(3-pyridyl)-1,2,4-triazole] (7b).
IR (KBr): ν = 705 (C S C), 1403, 1442 (C C), 1516, 1572 (C N), 2930 (C Haliph),
3065 (C Harom) cm−1; 1H NMR (DMSO-d6): δ = 2.65 (s, 6H, CH3),7.42 (t, J = 7.5 Hz,
2H, C Hpyridyl), 7.60 (d, J = 7.9 Hz, 2H, C Hpyridyl), 7.71 (s, 4H, C Hphenylene), 8.60 (s,
2H, C Hpyridyl), 8.63 (t, J = 7.1 Hz, 2H, C Hpyridyl); 13C NMR (DMSO-d6): δ = 15.0,
123.2, 123.9, 130.1, 135.3, 135.7, 148.9, 151.1, 152.7, 153.5; Anal. Calcd. for C22H18N8S2:
C, 57.62; H, 3.96; N, 24.44; S, 13.99. Found: C, 57.91; H, 4.11; N, 24.14; S, 14.19%.
4,4-(1,4-Phenylene)bis-[(3-methylthio)-5-(4-pyridyl)-1, 2, 4-triazole] (7c).
This compound was obtained as a dark brown precipitate. IR (KBr): ν = 700 (C S C),
1377, 1440 (C C), 1514, 1602 (C N), 2930 (CH3), 3055 (C Harom) cm−1;1H NMR
(DMSO-d6): δ = 2.67 (s, 6H, CH3), 7.30 (d, J = 2.9 Hz, 2H, C Hpyridyl), 7.74 (s, 4H,
C Hphenylene), 8.61 (d, J = 2.9 Hz, 4H, C Hpyridyl); Anal. Calcd. for C22H18N8S2: C, 57.62;
H, 3.96; N, 24.44; S, 13.99. Found: C, 57.69; H, 3.85; N, 24.53; S, 14.09%.
Preparation of Compounds 8a–c: General Procedure
Triazole salt 4a–c (0.1 g, 0.2 mmol) was dissolved in a mixture of acetone and
water (3:2, 20–30 mL). Ethyl 2-chloro acetate (0.43 mL, 0.4 mmol) was then added with
stirring. The reaction mixture was refluxed for the proper time (Table 1) and cooled to room
temperature to give a precipitate, which was filtered and washed with water (2 mL).
Diethyl 4,4-(1,4-phenylene)bis-[5-(2-pyridyl)-1,2,4-triazole-3-ylthio]diac-
etate (8a). IR (KBr): ν = 700 (C S C), 1178 (C O), 1300, 1448 (C C), 1516, 1591
(C N), 1722 (C O), 2974 (C Haliph), 3057 (C Harom) cm−1;1H NMR (DMSO-d6): δ =
1.20 (t, J = 7.0 Hz, 6H, CH3), 4.10–4.17 (m, 8H, OCH2 and SCH2), 7.40 (t, J = 6.2 Hz, 2H,
C Hpyridyl), 7.51 (s, 4H, C Hphenylene), 7.94 (d, J = 7.4, 2H, C Hpyridyl), 8.02 (d, J = 7.9
Hz, 2H, C Hpyridyl), 8.31 (d, J = 7.4 Hz, 2H, C Hpyridyl); Anal. Calcd. for C28H26N8O4
S2: C, 55.80; H, 4.35; N, 18.59; S, 10.64. Found: C, 56.08; H, 4.17; N, 18.73; S, 10.61%.
Diethyl 4,4-(1,4-phenylene)bis-[5-(3-pyridyl)-1,2,4-triazole-3-ylthio]diac-
etate (8b). IR (KBr): ν = 705 (C S C), 1178 (C O), 1311, 1389 (C C), 1438, 1516
(C N), 1726 (C O), 2978 (C Haliph), 3074 (C Harom) cm−1; 1H NMR (DMSO-d6): δ =
1.20 (t, J = 7.0 Hz, 6H, CH3), 4.10–4.17 (m, 8H, OCH2 and SCH2), 7.45 (d, J = 6.9 Hz,
2H, C Hpyridyl), 7.60 (d, J = 8.1, 2H, C Hpyridyl), 7.73 (s, 4H, C Hphenylen), 8.61 (m, 4H,
C Hpyridyl); Anal. Calcd. for C28H26N8O4 S2: C, 55.80; H, 4.35; N, 18.59; S, 10.64. Found:
C, 55.74; H, 4.64; N, 18.37; S, 10.73%.
Diethyl 4,4-(1,4-phenylene)bis-[5-(4-pyridyl)-1,2,4-triazole-3-ylthio]diac-
etate (8c). This compound was obtained as a light yellow precipitate. IR (KBr): ν =
702 (C S C), 1176 (C O), 1309, 1437 (C C), 1516, 1601 (C N), 1734 (C O), 2984
1
(C Haliph), 3051 (C Harom) cm−1; H NMR (DMSO-d6): δ = 1.20 (t, J = 7.1 Hz, 6H,
CH3), 4.10–4.16 (m, 8H, OCH2 and SCH2), 7.31 (d, J = 5.9 Hz, 4H, C Hpyridyl), 7.75
(s, 4H, C Hphenylen), 8.61 (d, J = 5.9 Hz, 4H, C Hpyridyl); 13C NMR (DMSO-d6): δ =
14.4, 34.5, 61.9, 122.3, 130.1, 134.0, 135.3, 150.5, 152.6, 152.9, 168.4; Anal. Calcd. for
C28H26N8O4 S2: C, 55.80; H, 4.35; N, 18.59; S, 10.64. Found: C, 55.54; H, 4.47; N, 18.27;
S, 10.87%.
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