# A Combined Synthetic and DFT Study on the Catalyst-Free and Solvent-Assisted Synthesis of 1,3,4-Oxadiazole-2-thiol Derivatives

Authors: Mohammad Soleiman-Beigi; Reza Aryan; Maryam Yousofizadeh; Shima Khosravi
Journal: Journal of Chemistry
 (2013)

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## Abstract

A novel practical and efficient catalyst-free method for the synthesis of 5-substituted 1,3,4-oxadiazole-2-thiols has been developed, which is assisted by reaction solvent (DMF). The solvent effects on product selectivity were studied based on Onsager’s reaction field theory of electrostatic solvation. The ab initio theoretical studies on the effect of solvents on the process also supported the suitability of DMF as the reaction medium for the preparation of 1,3,4-oxadiazole-2-thiol derivatives.


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## Body

## 1. Introduction

1,3,4-Oxadiazole-2-thiol(thione) derivatives are an important class of five-membered heterocyclic compounds that have attracted much attention due to their applications as key intermediates in organic synthesis [1–3], biological activity studies [4–6], and theoretical chemistry [7–9]. 1,3,4-Oxadiazole-2-thiol derivatives display various types of biological activities [10, 11], including antibacterial, antimycotic, anti-inflammatory, hypotensive, fungicidal, and anticonvulsant activities [12]. Recently, they were also found as trans-cinnamate 4-hydroxylase (C4H) [13] and glycogen synthesis kinase-3β (GSK-3β) inhibitors [14]. In addition, their derivatives play an important role in the field of coordination chemistry because of their potential multifunctional donor sites, via either exocyclic sulfur or endocyclic nitrogen atoms [15, 16].Although many studies have been reported concerning the biological activities and structural investigations of 1,3,4-oxadiazole-2-thiol derivatives, we have found only few procedures describing the synthesis, and no reports concerning the effect of solvent on the synthesis and tautomerization of these compounds in the literature. By far, the most common strategy for the synthesis of 1,3,4-oxadiazole-2-thiols involves the interaction of acid hydrazides with carbon disulfide in the presence of alcoholic potassium hydroxide [17–20]. In the past few years, catalyst-free reactions have been noticed as important routes for the development of  organic synthesis methodologies due to their environmentally friendly importance and economic advantages [21, 22]. Furthermore, in order to obtain pure 1,3,4-oxadiazole-2-thiols in the presence of a catalyst such as KOH, the reaction mixture should be neutralized because the parent compound of 1,3,4-oxadiazole-2-thiol is acidic (pKa=3.85) [23]. This makes the procedure rather difficult and reduces the yield of the product.In view of the importance of ab initio calculations to study the solvent effects in the synthesis and tautomerization of organic compounds [24, 25] and the above-mentioned issues, we have been prompted to investigate the synthesis of 1,3,4-oxadiazole-2-thiols in solution conditions and to explore the effect of solvent both experimentally and theoretically.


## 2. Results and Discussion

To optimize the reaction conditions with regard to the solvent, the reaction of benzhydrazide (1.0 mmol) with carbon disulfide (3.0 mmol) was primarily studied as the model reaction in a variety of accessible solvents at 70°C (Table1). As shown in Table 1, the best result was obtained in DMF (entry 5).Table 1
Ring closure of substrates as a function of solvent.
Entry
Solvent
Time (h)
Yields(%)*
(1)
C2H5OH
21
10
(2)
CHCl3
21
—
(3)
CH3CN
21
72
(4)
PhCH3
23
trace
(5)
DMF
3
92
(6)
H2O
18
8
(7)
DMF/H2O (10/1)
7.2
64
(8)
DMF/H2O (4/1)
8.5
48
*Isolated yield of pure product.It seems that the polarity of aprotic organic solvents has a great effect on the yield of 1,3,4-oxadiazole-2-thiol. The yield of the product increases with increasing dipole moment of the organic aprotic solvent (Table1).Various aliphatic, aromatic, and heteroaromatic hydrazides were tested in DMF at 70°C (Scheme1). Aromatic and heteroaromatic hydrazides gave target products in good to excellent yields (Table 2), whereas the procedure did not work with aliphatic hydrazide as well as aromatics and heteroaromatic hydrazides to yield target products (Table 2, entry 13).Table 2
Synthesis of 5-substituted 1,3,4-oxadiazole-2-thiols4in DMF.
Entry
Products
Time(h)
Yields(%)*
(1)
4a
4.45
70
(2)
4b
3.20
96
(3)
4c
3.45
94
(4)
4d
3.30
87
(5)
4e
7.0
91
(6)
4f
6.0
81
(7)
4g
4.0
84
(8)
4h
6.0
85
(9)
4i
8.0
61
(10)
4j
9.0
80
(11)
4k
3.30
96
(12)
4l
4.50
98
(13)
4m
12.0
trace
*Isolated yield of pure product.Scheme 1In fact, from these reactions, we have isolated 1,3,4-oxadiazole-2-thiols4 with no evidence for the formation of any byproducts such as 1,3,5-thiadiazole 5 or 1,5-dibenzoyl-thiocarbazide 6 derivatives (Scheme 2).Scheme 2The results from these experiments encouraged us to investigate the effect of solvent on this reaction theoretically with ab initio Lee-Young-Parr (B3LYP) level of theory using Gaussian 03w software program [26] on a Pentium IV computer. The structures of two possible tautomers of 1,3,4-oxadiazole-2-thiol(thione) are presented in Figure 1.Figure 1
Equilibrium between 1,3,4-oxadiazole-2-thiol and 2-thione tautomers.The geometry optimizations of the tautomers (I) and (II) were carried out at B3LYP/6-311++G(d,p) with taking into account the polarity of medium in gas phase (ε=1) and in different solvents using self-consistent reaction field (SCRF) method by using SCIPCM solvent model (Table 3). The values of absolute energy (E) and solvent-solute interaction energy in Table 3 indicate more stability (more negative value) for both tautomers in more polar solvents (Table 3, E and ESSI columns). The highest solution energy values (difference between gaseous and solvated states) for tautomer (I) and (II) are in DMF and CH3CN, respectively (ES = 5.0459 kcal/mol for tautomer (I) in DMF and ES = 6.4991 kcal/mol for tautomer II in CH3CN). Furthermore, when the ES values in different solvents are examined, the orders of tautomers stability according to ES values are as follows (see Table 3, the values of ES):
(1)fortautomer(I),DMF>CH3CN>C2H5OH>CH2Cl2>Toluene,fortautomer(II),CH3CN>DMF>C2H5OH>CH2Cl2>Toluene.Table 3
Calculated energies and dipole moments at the B3LYP level with 6-311++G**.
Parameter
Tautomer
ε = 1
ε = 36.7
ε = 36.04
ε = 24.3
ε = 8.93
ε = 2.38
E
a
I
−891.5045327
−891.5125739
−891.5125732
−891.5123820
−891.5114328
−891.5082445
E
a
II
−891.5219806
−891.532338
−891.532345
−891.532098
−891.530870
−891.526763
E
SSI
b
I
—
−891.5125695
−891.5125688
−891.5123776
−891.5114296
−891.5081894
E
SSI
b
II
—
−891.5323358
−891.5323396
−891.5320928
−891.5308670
−891.5267218
E
HB
c
I
—
5.0432
5.0427
4.9228
4.3279
2.2946
E
HB
c
II
—
6.4980
6.5004
6.3455
5.5764
2.9752
E
S
d
I
—
5.0459
5.0455
4.9255
4.3299
2.3292
E
S
d
II
—
6.4991
6.5039
6.3485
5.5779
3.0013
ΔEHBe
—
—
1.4548
1.4577
1.4227
1.2485
0.6806
ΔESf
—
—
1.4532
1.4584
1.4230
1.2480
0
.
6721
μ
h
I
0.9773
1.3208
1.3207
1.3117
1.2664
1.1266
μ
h
II
1.7771
2.3823
2.3838
2.3699
2.3012
2.0700
aEnergy (hartrees). bSolvent-solute interaction energy (hartrees). cHydrogen bond strength (kcal/mol).  dSolution energy (kcal/mol). eDifference between the hydrogen bond strength  of I and II (EHB(II)-EHB(I))  in kcal/mol. fDifference between the solvation energies  of I and II (ES(II)-ES(I)) in kcal/mol. hDipole moment (debye).Therefore, the highest calculatedEHB and ΔEHB (difference between EHB of both tautomers) values were obtained in DMF and acetonitrile with highest dipole moments. These findings emphasize the role of more polar solvents such as DMF and acetonitrile in the formation of 1,3,4-oxadiazole-2-thiol(thione). Most importantly, it can be seen that tautomer (I) has the lowest solution energy (more stability) in DMF in comparison to tautomer (II), which prefers acetonitrile (Table 3).Moreover, calculations reveal that the highest dipole moment for tautomers (I) and (II) would be in DMF and acetonitrile, respectively. Herein, these data again support that the formation of (I) (thiol tautomer) is favored over the other tautomer in DMF as reaction solvent.To ensure that hydrogen bonding with solvents of high polarity has a significant contribution in facilitating the formation of and stabilizing the thiol tautomer, we considered purposefully the changes in bond lengths and angles of two tautomers (Tables4 and 5).Table 4
The geometrical parameters of the tautomer I calculated at the B3LYP level with 6-311++G** basis seta.
ε = 1
ε = 36.7
ε = 36.04
ε = 24.3
ε = 8.93
ε = 2.38
Bond lengths
C1=N4
1.2941
1.2955
1.2955
1.2954
1.2953
1.2947
C2=N5
1.2925
1.2951
1.2951
1.2950
1.2946
1.2936
C2–O3
1.3570
1.3554
1.3554
1.3555
1.3558
1.3563
C1–O3
1.3769
1.3738
1.3738
1.3739
1.3743
1.3759
C2–S17
1.7520
1.7497
1.7497
1.7497
1.7502
1.7510
S17–H18
1.3485
1.3476
1.3476
1.3476
1.3477
1.3480
C1–C6
1.4568
1.4570
1.4570
1.4570
1.4569
1.4569
C6–C7
1.4029
1.4033
1.4033
1.4033
1.4033
1.4031
C7–C9
1.3891
1.3898
1.3898
1.3898
1.3896
1.3894
C9–C13
1.3961
1.3967
1.3967
1.3967
1.3967
1.3964
C13–C11
1.3937
1.3945
1.3945
1.3944
1.3943
1.3940
C11–C8
1.3918
1.3921
1.3921
1.3921
1.3921
1.3919
C8–C6
1.4010
1.4018
1.4018
1.4018
1.4017
1.4014
Bond angles
N5C2S17
129.73
130.27
130.27
130.26
130.25
129.94
H18S17C2
92.70
93.49
93.49
93.47
93.40
93.04
N4C1C6
129.13
129.45
129.45
129.44
129.40
129.28
C1O3C2
102.24
102.75
102.75
102.74
102.68
102.47
N5N4C1
107.18
107.11
107.11
107.12
107.13
107.16
aBond lengths and bond angles are in Å  and degrees, respectively.Table 5
The geometrical parameters of the tautomer I calculated at the B3LYP level with 6-311++G** basis seta.
ε = 1
ε = 36.7
ε = 36.04
ε = 24.3
ε = 8.93
ε = 2.38
Bond lengths
C2=N16
1.2924
1.2932
1.2929
1.2929
1.2930
1.2926
C2–N17
1.3559
1.3460
1.3459
1.3461
1.3472
1.3515
C2–O15
1.3823
1.3745
1.3747
1.3750
1.3762
1.3781
C3–O15
1.3709
1.3725
1.3725
1.3727
1.3721
1.3724
C2–S1
1.6404
1.6552
1.6549
1.6545
1.6527
1.6471
N17–H18
1.0073
1.0102
1.0100
1.0100
1.0096
1.0085
C3–C4
1.4565
1.4560
1.4560
1,4561
1.4562
1.4561
C4–C6
1.4028
1.4037
1.4036
1.4036
1.4035
1.4032
C6–C9
1.3886
1.3895
1.3891
1.3891
1.3888
1.3888
C9–C11
1.3965
1.3971
1.3971
1.3971
1.3970
1.3968
C11–C7
1.3935
1.3945
1.3943
1.3943
1.3942
1.3938
C7–C5
1.3918
1.3923
1.3923
1.3923
1.3922
1.3919
C4–C5
1.4008
1.4017
1.4014
1.4014
1.4013
1.4010
Bond angles
H18N17C2
125.51
126.38
126.32
126.30
126.20
125.92
N16C3C4
127.98
128.35
128.14
128.13
128.10
128.14
C4C3O15
119.31
119.38
119.57
119.57
119.53
119.38
N17N16C3
103.50
103.77
103.78
103.77
103.71
103.65
N17C2O15
102.98
103.78
103.80
103.77
103.66
103.37
N17C2S1
131.15
131.43
131.19
131.19
131.24
131.16
aBond lengths and bond angles are in Å and degrees, respectively.The values of C1=N4 and C2=N5 bond lengths (consider Figure1 and Tables 4 and 5) experience maximum increment, while the C2–S17, C1–O3, C2–O3, and S17–H18 bond lengths experience maximum decline in DMF as solvent in comparison with gas phase values for tautomer (I). It is believed that these changes are the consequences of hydrogen bond formation between tautomer (I) and dimethylformamide as solvent. Similar phenomenon is observed for tautomer (II) in acetonitrile proving the idea of solvent assistance for the tautomer selectivity. According to these findings, the tautomer (I) is preferred mostly to be formed in DMF as solvent.The structure of the compounds obtained has been confirmed by their NMR, IR, and physical properties. The IR spectrum of the product 4 exhibited characteristic weak bands at 3270–3050 cm−1(NH), 2780–2720 cm−1(SH), and 1630–1600 cm−1 (C=N). 1H-NMR (DMSO-d6) spectrum of the products 4 showed only one proton as singlet at 14.0–15.5 ppm. This information suggested that the product 4, which was synthesized via the present method, existed mostly in the thiol form in solution, whereas the thiol-thione tautomerism was observed in their solid crystalline forms where the effect of solvent on tautomerism is cancelled. This fact is supported by DFT calculations in gaseous and solution phases. The energy difference between two tautomers is about 10.9 kcal/mol, which is accessible at room temperature (see Table 3, columns for E, ε=1.0) and proves the observation of NH and SH bands in IR spectrum. This tautomerism is of course too fast to be observed in NMR.In summary, we have developed a novel and efficient catalyst-free and solvent-assisted protocol for the synthesis of 5-substituted 1,3,4-oxadiazole-2-thiols with potential synthetic and pharmacological interest. Catalyst-free conditions, excellent yields, a simplified purification process, short reaction times, and safe handling of products are the main advantages of this method. The influence of solvents on the progress of the reaction has been studied experimentally and theoretically. DMF, as an accessible polar aprotic solvent, was found as most convenient medium to facilitate this process for the synthesis of 1,3,4-oxadiazole-2-thiols. Theoretical calculations using ab initio density functional theory (DFT) at B3LYP/6-311++G(d,p) level of theory confirmed that dimethylformamide (DMF) assisted the formation of only one of the expected tautomers (tautomer I) as the single observable product of the reaction.


## 3. Experimental

Chemicals were purchased from Merck and Aldrich chemical companies. Yields refer to isolated products. Melting points were determined by a Electrothermal 9100 apparatus. The IR spectra were obtained on a FT-IR Hartman-Bomen spectrophotometer as KBr disks. The1H NMR (400 MHz) and 13C NMR (100 MHz) spectra were recorded on a Bruker Avance NMR spectrometer in DMSO-d6 solutions. Elemental analyses were done on a Carlo-Erba EA1110CHNO-S analyzer. The progress of the reaction was followed by TLC using silica-gel SIL G/UV 254 plates. Products were characterized by comparing their physical and spectral data with those of the authentic samples [5, 17].


### 3.1. General Procedure for Synthesis of 5-Substituted 1,3,4-Oxadiazole-2-thiol Derivatives4a–m

A mixture of acid hydrazide (1.0 mmol) and carbon disulfide (3.0 mmol) in DMF (2.0 mL) was stirred for 15 min at room temperature. The reaction mixture was then heated at 70°C for appropriated time (Table2) until the ring closure completed. The reaction progress was checked by TLC monitoring (ethyl acetate: n-hexane (1 : 2)). After cooling to room temperature, the reaction mixture was poured dropwise into ice cold water (15 mL) to yield a solid (title compounds 4), which was collected by filtration, washed with water, and recrystallized from EtOH/water to give compounds 4a–m in good to excellent yields.


#### 3.1.1.5-(4-Hydroxyphenyl)-1,3,4-oxadiazole-2-thiol 4a

mp 225–228°C;1H NMR (DMSO-d6): δ 6.93(d, 2H), 7.72(d, 2H), 10.40(s, 1H, OH), 14.53(br s, 1H, SH). 13C NMR (DMSO-d6):δ 177.02, 162.41, 153.12, 128.12, 113.99, 108.93. IR (KBr disc): ν 3296, 3160, 2359, 1271 cm−1. Anal. Calcd. For C8H6N2O2S: C, 49.47; H, 3.11; N, 14.42. Found: C, 49.38; H, 3.09; N,14.54.


#### 3.1.2. 5-Phenyl-1,3,4-oxadiazole-2-thiol4b

mp 218-219°C;1H NMR (DMSO-d6): δ7.58(m, 3H), 7.85(m, 2H), 14.8(br s, 1H, SH). 13C NMR (DMSO-d6): δ 123.00, 126.49, 129.88, 132.65, 160.65, 177.97. IR (KBr disc): ν 3143, 2352, 1289 cm−1. Anal. Calcd. for C8H6N2OS: C, 53.92; H, 3.39; N, 15.72. Found: C, 53.86; H, 3.42; N, 15.66.


#### 3.1.3. 5-(3-Pyridyl)-1,3,4-oxadiazole-2-thiol4e

mp 226-227°C.1H NMR (DMSO-d6): δ 7.59–7.62(m, 1H), 8.24(d, 1H), 8.78(d, 1H), 9.30(s, 1H), 14.83(br s, 1H, SH). 13C NMR (DMSO-d6): δ 119.74, 124.72, 134.16, 147.19, 152.97, 159.21, 162.74, 178.05. IR (KBr disc): ν 3183, 2360, 1247 cm−1. Anal. Calcd. for C7H5N3OS: C, 46.92; H, 2.81; N, 23.45. Found: C, 46.80; H, 2.90; N, 23.40.


#### 3.1.4. 5-(2-Chlorophenyl)-1,3,4-oxadiazole-2-thiol4l

mp 166–169°C.1H NMR (DMSO-d6): δ 7.55(t, 1H), 7.64(t, 1H), 7.70(d, 1H), 7.90(d, 1H), 14.8(br s, 1H, SH). 13C NMR (DMSO-d6): δ 121.86, 128.32, 131.25, 131.67, 131.99, 133.78, 158.91, 177.85. IR (KBr disc): ν 3277, 2353, 1277 cm−1. Anal. Calcd. for C8H5ClN2OS: C, 45.18; H, 2.37; N,13.17. Found: C, 45.01; H, 2.51; N, 13.15.


## 3.1. General Procedure for Synthesis of 5-Substituted 1,3,4-Oxadiazole-2-thiol Derivatives4a–m

A mixture of acid hydrazide (1.0 mmol) and carbon disulfide (3.0 mmol) in DMF (2.0 mL) was stirred for 15 min at room temperature. The reaction mixture was then heated at 70°C for appropriated time (Table2) until the ring closure completed. The reaction progress was checked by TLC monitoring (ethyl acetate: n-hexane (1 : 2)). After cooling to room temperature, the reaction mixture was poured dropwise into ice cold water (15 mL) to yield a solid (title compounds 4), which was collected by filtration, washed with water, and recrystallized from EtOH/water to give compounds 4a–m in good to excellent yields.


### 3.1.1.5-(4-Hydroxyphenyl)-1,3,4-oxadiazole-2-thiol 4a

mp 225–228°C;1H NMR (DMSO-d6): δ 6.93(d, 2H), 7.72(d, 2H), 10.40(s, 1H, OH), 14.53(br s, 1H, SH). 13C NMR (DMSO-d6):δ 177.02, 162.41, 153.12, 128.12, 113.99, 108.93. IR (KBr disc): ν 3296, 3160, 2359, 1271 cm−1. Anal. Calcd. For C8H6N2O2S: C, 49.47; H, 3.11; N, 14.42. Found: C, 49.38; H, 3.09; N,14.54.


### 3.1.2. 5-Phenyl-1,3,4-oxadiazole-2-thiol4b

mp 218-219°C;1H NMR (DMSO-d6): δ7.58(m, 3H), 7.85(m, 2H), 14.8(br s, 1H, SH). 13C NMR (DMSO-d6): δ 123.00, 126.49, 129.88, 132.65, 160.65, 177.97. IR (KBr disc): ν 3143, 2352, 1289 cm−1. Anal. Calcd. for C8H6N2OS: C, 53.92; H, 3.39; N, 15.72. Found: C, 53.86; H, 3.42; N, 15.66.


### 3.1.3. 5-(3-Pyridyl)-1,3,4-oxadiazole-2-thiol4e

mp 226-227°C.1H NMR (DMSO-d6): δ 7.59–7.62(m, 1H), 8.24(d, 1H), 8.78(d, 1H), 9.30(s, 1H), 14.83(br s, 1H, SH). 13C NMR (DMSO-d6): δ 119.74, 124.72, 134.16, 147.19, 152.97, 159.21, 162.74, 178.05. IR (KBr disc): ν 3183, 2360, 1247 cm−1. Anal. Calcd. for C7H5N3OS: C, 46.92; H, 2.81; N, 23.45. Found: C, 46.80; H, 2.90; N, 23.40.


### 3.1.4. 5-(2-Chlorophenyl)-1,3,4-oxadiazole-2-thiol4l

mp 166–169°C.1H NMR (DMSO-d6): δ 7.55(t, 1H), 7.64(t, 1H), 7.70(d, 1H), 7.90(d, 1H), 14.8(br s, 1H, SH). 13C NMR (DMSO-d6): δ 121.86, 128.32, 131.25, 131.67, 131.99, 133.78, 158.91, 177.85. IR (KBr disc): ν 3277, 2353, 1277 cm−1. Anal. Calcd. for C8H5ClN2OS: C, 45.18; H, 2.37; N,13.17. Found: C, 45.01; H, 2.51; N, 13.15.


## 3.1.1.5-(4-Hydroxyphenyl)-1,3,4-oxadiazole-2-thiol 4a

mp 225–228°C;1H NMR (DMSO-d6): δ 6.93(d, 2H), 7.72(d, 2H), 10.40(s, 1H, OH), 14.53(br s, 1H, SH). 13C NMR (DMSO-d6):δ 177.02, 162.41, 153.12, 128.12, 113.99, 108.93. IR (KBr disc): ν 3296, 3160, 2359, 1271 cm−1. Anal. Calcd. For C8H6N2O2S: C, 49.47; H, 3.11; N, 14.42. Found: C, 49.38; H, 3.09; N,14.54.


## 3.1.2. 5-Phenyl-1,3,4-oxadiazole-2-thiol4b

mp 218-219°C;1H NMR (DMSO-d6): δ7.58(m, 3H), 7.85(m, 2H), 14.8(br s, 1H, SH). 13C NMR (DMSO-d6): δ 123.00, 126.49, 129.88, 132.65, 160.65, 177.97. IR (KBr disc): ν 3143, 2352, 1289 cm−1. Anal. Calcd. for C8H6N2OS: C, 53.92; H, 3.39; N, 15.72. Found: C, 53.86; H, 3.42; N, 15.66.


## 3.1.3. 5-(3-Pyridyl)-1,3,4-oxadiazole-2-thiol4e

mp 226-227°C.1H NMR (DMSO-d6): δ 7.59–7.62(m, 1H), 8.24(d, 1H), 8.78(d, 1H), 9.30(s, 1H), 14.83(br s, 1H, SH). 13C NMR (DMSO-d6): δ 119.74, 124.72, 134.16, 147.19, 152.97, 159.21, 162.74, 178.05. IR (KBr disc): ν 3183, 2360, 1247 cm−1. Anal. Calcd. for C7H5N3OS: C, 46.92; H, 2.81; N, 23.45. Found: C, 46.80; H, 2.90; N, 23.40.


## 3.1.4. 5-(2-Chlorophenyl)-1,3,4-oxadiazole-2-thiol4l

mp 166–169°C.1H NMR (DMSO-d6): δ 7.55(t, 1H), 7.64(t, 1H), 7.70(d, 1H), 7.90(d, 1H), 14.8(br s, 1H, SH). 13C NMR (DMSO-d6): δ 121.86, 128.32, 131.25, 131.67, 131.99, 133.78, 158.91, 177.85. IR (KBr disc): ν 3277, 2353, 1277 cm−1. Anal. Calcd. for C8H5ClN2OS: C, 45.18; H, 2.37; N,13.17. Found: C, 45.01; H, 2.51; N, 13.15.



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*Source: 476358-2012-08-29.xml*