In situ generated hypoiodous acid in an efficient and heterogeneous catalytic system for the homo-oxidative coupling of thiols

Article abstract of DOI:10.2298/JSC120223054G

Supported hydrogen peroxide on polyvinylpolypyrrolidone (PVPP- -H ₂O₂), silica sulfuric acid (SiO₂-OSO ₃H) and catalytic amounts of potassium iodide (KI) was developed as a heterogeneous medium for the rapid oxidative coupling of thiols into symmetrical homodisulfides. This oxidizing system proceeds under extremely mild conditions and gives no other oxidized side products.

Full text of DOI:10.2298/JSC120223054G

J. Serb. Chem. Soc. 78 (2) 173–178 (2013)
JSCS–4406
UDC 546.215+546.153.3–32+
544.47:544.344:547.367
Short communication
SHORT COMMUNICATION
In situ generated hypoiodous acid in an efficient and
heterogeneous catalytic system for the homo-oxidative
coupling of thiols
ARASH GHORBANI-CHOGHAMARANI*, MOHSEN NIKOORAZM
and GOUHAR AZADI
Department of Chemistry, Faculty of Science, Ilam University,
P. O. Box 69315516, Ilam, Iran
(
Received 23 February, revised 17 May 2012)
Abstract: Supported hydrogen peroxide on polyvinylpolypyrrolidone (PVPP–
–
H O ), silica sulfuric acid (SiO –OSO H) and catalytic amounts of potassium
2 2 2 3
iodide (KI) was developed as a heterogeneous medium for the rapid oxidative
coupling of thiols into symmetrical homodisulfides. This oxidizing system
proceeds under extremely mild conditions and gives no other oxidized side
products.
Keywords: supported hydrogen peroxide on polyvinylpolypyrrolidone; po-
tassium iodide; silica sulfuric acid.
INTRODUCTION
In recent years, supported reagents on polymeric structures have become
1
–5
increasingly popular in organic synthesis,
because of their mild and hetero-
geneous nature together with advantages of easy work-up of the products. The
conversion of thiols to the corresponding disulfides is an important and inte-
resting transformation in organic chemistry due to the central importance of this
functional group in diverse areas of chemistry and biology,6–11 and oxidation is
the most common methodology used for their preparation because of the com-
mercial availability of thiols. A variety of oxidants have been reported for the
conversion of thiols into disulfides, such as tributylammonium halochromates/
1
2
13
14
/
(
silica gel, Fe(HSO ) or Fe(HSO ) /DMSO, Al(NO ) ⋅9H O/SiO –OSO H,
4
3
4 3
3 3
2
2
16
3
1
5
C H ) NH[CrO X], (X = F or Cl)/Al O , N-bromosuccinimide, poly(4-vi-
3 7 3 3 2 3
1
7
18
nylpyridinium nitrate), H O /NaI, urea–hydrogen peroxide/maleic anhyd-
2
2
1
9
20
ride,
ethylenebis(N-methylimidazolium) chlorochromate,
manganese(III)
*
Corresponding author. E-mail: arashghch58@yahoo.com; a.ghorbani@mail.ilam.ac.ir
doi: 10.2298/JSC120223054G
1
73
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GHORBANI-CHOGHAMARANI, NIKOORAZM and AZADI
Schiff-base complexes,21 Au/CeO , Co(II) and Mn(II) salts of 4-aminobenzoic
22
2
2
3
acid supported on silica gel and Zn(II)–Al(III) double layer hydroxide with
VI
2– 24
intercalated [Mo O (O CC(S)Ph ) ] . Some of these procedures suffer from
2
2
2 2
one or more disadvantages, such as long reaction times, overoxidation, tedious
work-up, low yields of the products, heavy metal contamination, harsh con-
ditions, and expensive reagents or catalysts.
Hydrogen peroxide (H O ) is a powerful oxidizing agent that has been used
2
2
2
5,26
as an oxidant for the oxidation of different types of organic moieties,
and in
order to avoid the hazards connected with the use of concentrated solutions of
2
5,27,28
hydrogen peroxide, this compound has been used supported on a carrier.
In this regard, polyvinylpolypyrrolidone-supported hydrogen peroxide (PVPP–
H O ) has proved to be one of the most popular choices with its advantages of
2
2
insolubility in organic solvents, easy work-up of products, non-toxic content and
mild oxidizing properties. Therefore, it was decided to study the application of
this polymeric reagent for the oxidative homocoupling of thiols in conjunction
with silica sulfuric acid (SiO –OSO H) and catalytic amounts of potassium iodide
2
3
(KI).
RESULTS AND DISCUSSION
In connection with an ongoing program related to the application of new
reagents or reagent systems for organic functional group transformations,29–35
the preparation of polyvinylpolypyrrolidone-supported hydrogen peroxide
(
PVPP–H O ) and its application to the synthesis of symmetrical disulfides from
2 2
the corresponding thiols were considered of interest.
Therefore, in this study it was decided to design an efficient catalytic system
including polyvinylpolypyrrolidone-supported hydrogen peroxide (PVPP–H O ),
2
2
silica sulfuric acid and potassium iodide (as catalyst) for the in situ generation of
hypoiodous acid (IOH), as the active oxidant. A variety of aliphatic and aromatic
thiols 1 were converted to the corresponding disulfides 2 using polyvinylpoly-
pyrrolidone-supported hydrogen peroxide (PVPP–H O ) and silica sulfuric acid
2
2
(
SiO –OSO H) in the presence of catalytic amounts of potassium iodide (KI) in
2 3
dichloromethane or ethyl acetate (as solvent) at room temperature (Scheme 1).
The results of this transformation are summarized in Table I.
H2
C
H
C
N
O .H O2
2
n
R SH
RS SR
SiO -OSO H, KI
2
3
CH Cl or CH COOEt, rt
2
2
3
1
2
Scheme 1. Oxidative coupling of thiols.
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HOMO-OXIDATIVE COUPLING OF THIOLS via HETEROGENEOUS MEANS
175
TABLE I. Oxidative coupling of thiols into disulfides using PVPP–H O and SiO –OSO H in
2
2
2
3
the presence of a catalytic amount of KI at room temperature
Melting point, °C
Found Reported
Entry Substrate
Producta
Time, min Yield, %b
Ref.
1
40
99
55–58 59–61 34
SH
S
S
2
15
1440
1440
60
99
54c
91d
86
91–93 89–92 17
91–93 89–92 17
91–93 89–92 17
288–292 273–285 17
Br
Br
Br
SH
Br
Br
S
S
Br
Br
Br
3
4
5
SH
SH
S
S
S
S
Br
COOH
SH
COOHHOOC
S
S
6
7
8
H C
S
30
30
30
99
83
97
40–43 39–42 17
H3C
SH
3
S
CH3
–
–
19
CH2SH
CH2S SH2C
O
O
O
93–98 84–88 17
174–177 177–179 17
SH
S
S
N
S
N
S
N
S
9
1
40
40
95
99
SH
SH
S
S
S
S
N
N
N
0
135–138 141–144 17
e
1
1
a
1
2
HSCH2CH2OH
HSCH2COOH
HOCH2CH2S SCH2CH2OH
HOOCCH2S SCH2COOH
20
20
82
98
/
/
/
34
17
/
b
c
Substrate/PVPP–H O /SiO –OSO H/KI = 1 mmol/0.175 g/0.1 g/0.02 mmol; isolated yield; in the absence
2
2
2
3
d
e
of KI; in the absence of silica sulfuric acid; oil
All of the coupling reactions were realized under completely heterogeneous
conditions in which the product was easily obtained by simple filtration, washing
1
the filtrate with an organic solvent and evaporation. Subsequent TLC and H-NMR
spectroscopic analysis of the residue in each case revealed purity to be > 95 %.
In order to demonstrate the role of potassium iodide as catalyst in the des-
cribed system, it was decided to design a reaction in the absence of this com-
pound. Therefore, 4-bromothiophenol was reacted with polyvinylpolypyrroli-
done-supported hydrogen peroxide and silica sulfuric acid in the absence of po-
tassium iodide. As is evident from Table I (entry 3), 1,2-bis(4-bromophenyl)-
disulfane was obtained in 54 % yield after 24 h, which is much less efficient than
with the potassium iodide (15 min, 99 % yield) . In addition, in order to study the
role of the acid, 4-bromothiophenol (as a typical example) was subjected to oxi-
dative coupling by PVPP–H O and catalytic amounts of KI in the absence of
2
2
silica sulfuric acid. In this case, it was observed that the reaction time was in-
creased to 24 h and 1,2-bis(4-bromophenyl)disulfane was obtained in 91 % yield
(
Table I, entry 4). Thus, it was concluded that the presence of both the acid and
potassium iodide was necessary for the rapid and efficient conversion of a thiol
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GHORBANI-CHOGHAMARANI, NIKOORAZM and AZADI
into the corresponding disulfide by polyvinylpolypyrrolidone-supported hyd-
rogen peroxide (PVPP–H O ). A range of thiols were converted and a range of
2
2
functional groups are chemoselectively tolerated (HO, CO H, heteroaromatic).
2
A plausible mechanism for this conversion is outlined in the catalytic cycle
1
8,31,32,36
shown in Scheme 2 based on previously reported work.
The key is the
production of hypoiodous acid (HOI) as the active oxidant to form a sulfenyl
iodide RSI as an intermediate. Coupling of this with another molecule of thiol
produces the homodisulfide with formation of HI, which exchanges with the po-
tassium salt of silica–sulfuric acid (Scheme 2) to regenerate KI. In this way, HI is
not built up in the reaction.
Scheme 2. Mechanism of coupling of thiols by in situ generated iodine.
EXPERIMENTAL
Materials and methods
All chemicals and solvents were purchased from Fluka, Merck or Aldrich and were used
without further purification. Polyvinylpolypyrrolidone-supported hydrogen peroxide (PVPP–
3
7,38
–
H O ) was prepared via the procedure reported by Pourali and Ghanei.
Silica sulfuric
2
2
3
9
acid was prepared via the procedure by reported Zolfigol. All the prepared disulfides are
known and were characterized by comparison of their spectral (IR, H-NMR or C-NMR)
and physical data with those of authentic samples.
1
13
General procedure for the oxidative coupling of thiols using PVPP–H O /SiO –OSO H/KI
2
2
2
3
To a suspension of polyvinylpolypyrrolidone-supported hydrogen peroxide (0.175 g),
silica sulfuric acid (0.1 g) and potassium iodide (0.02 mmol) in dichloromethane or ethyl
acetate (5 mL) was added a thiol (1 mmol), and the mixture was stirred at room temperature
for the specified time (Table I). The progress of the reaction was monitored by TLC. After
completion of the reaction, the reaction mixture was filtered and the residue washed with
CH Cl (20 mL), (the residue of entry 5 was washed with ethanol). Finally, the organic
2
2
1
solvent was evaporated and pure product was obtained as judged by TLC and H-NMR
spectroscopy.
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HOMO-OXIDATIVE COUPLING OF THIOLS via HETEROGENEOUS MEANS
177
CONCLUSIONS
In summary, it was demonstrated in this research that polyvinylpolypyr-
rolidone-supported hydrogen peroxide (PVPP–H O ) is a practical and versatile
2
2
oxidizing polymer, which is able to convert a variety of thiols into disulfides in
the presence of an acid and iodide salt. The presence of silica sulfuric acid and
potassium iodide was found to be critical for the conversion, and the isolation of
the product was facile.
Acknowledgement. The financial support for this work by the Ilam University, Ilam, Iran
is gratefully acknowledged.
И З В О Д
IN SITU СТВАРАЊЕ ХИПОЈОДАСТЕ КИСЕЛИНЕ У ЕФИКАСНОМ ХЕТЕРОГЕНОМ
КАТАЛИТИЧКОМ СИСТЕМУ ЗА ХОМО-ОКСИДАТИВНО КУПЛОВАЊЕ ТИОЛА
ARASH GHORBANI-CHOGHAMARANI, MOHSEN NIKOORAZM и GOUHAR AZADI
Department of Chemistry, Faculty of Science, Ilam University, P. O. Box 69315516, Ilam, Iran
Развијен је хетероген систем који садржи водоник-пероксид на поливинилполи-
пиролидину (PVPP–H O ), сумпорну киселину на силика-гелу (SiO –OSO H) и катали-
2
2
2
3
тичку количину калијум-јодида (KI). Овакав хетероген систем успешно генерише ката-
литичке количине хипојодасте киселине за брзо оксидативно купловање тиола до симет-
ричних хомодисулфида. Оксидациони систем је ефикасан при благим реакционим ус-
ловима и не производи друге споредне производе оксидације.
(
Примљенo 23. фебруара, ревидирано 17. маја 2012)
REFERENCES
1. M. A. Karimi-Zarchi, B. F. Mirjalili, Z. Shamsi-Kahrizsangi, M. Tayefi, J. Iran. Chem.
Soc. 7 (2010) 455
2
3
4
5
. A. Ghorbani-Choghamarani, Z. Chenani, S. Mallakpour, Synth. Commun. 39 (2009) 4264
. M. A. Chari, K. Syamasundar, Catal. Commun. 6 (2005) 67
. N. Iranpoor, B. Tamami, K. Niknam, Can. J. Chem. 75 (1997) 1913
. V. Mirkhani, M. Moghadam, S. Tangestaninejad, S. Hajibagheri, J. Iran. Chem. Soc. 7
(
2010) 641
. J. M. Herrmann, F. Kauff , H. E. Neuhaus, Biochim. Biophys. Acta – Mol. Cell Res. 1793
2009) 71
. B. A. Maron, Y. Y. Zhang, D. E. Handy, A. Beuve, S. S. Tang, J. Loscalzo, J. A.
Leopold, J. Biol. Chem. 284 (2009) 7665
6
7
8
9
(
. S. Fukuzawa, E. Shimizu, Y. Atsuumi, M. Haga, K. Ogata, Tetrahedron Lett. 50 (2009)
2
374
. Y. H. Seoa, K. S. Carroll, Proc. Natl. Acad. Sci. USA 106 (2009) 16163
1
1
1
0. C. Tidei, M. Piroddi, F. Galli, C. Santi, Tetrahedron Lett. 53 (2012) 232
1. D. Witt, Synthesis (2008) 2491
2. M. K. Mohammadi, S. Ghammamy, S. Zarrinabadi, M. H. Farjam, B. Sabayan, Chin. J.
Chem. 28 (2010) 2199
13. H. Eshghi, M. Bakavoli, H. Moradi, A. Davoodnia, Phosphorus Sulfur Silicon Relat.
Elem. 184 (2009) 3110
Available online at shd.org.rs/JSCS/
_________________________________________________________________________________________________________________________
_
2
013 Copyright (CC) SCS

1
78
GHORBANI-CHOGHAMARANI, NIKOORAZM and AZADI
1
1
4. A. Ghorbani-Choghamarani, M. Nikoorazm, H. Goudarziafshar, B. Tahmasbi, Bull.
Korean Chem. Soc. 30 (2009) 1388
5. A. HassaniJoshaghani, S. Ghammamy, S. Bagi, A. Moghimi, Z. Javanshir, Phosphorus
Sulfur Silicon Relat. Elem. 184 (2009) 164
1
1
1
1
2
6. H. Ghafuri, M.M. Hashemi, J. Sulfur Chem. 30 (2009) 578
7. A. Ghorbani-Choghamarani, S. Sardari, J. Sulfur Chem. 32 (2011) 63
8. M. Kirihara, Y. Asai, S. Ogawa, T. Noguchi, A. Hatano, Y. Hirai, Synthesis (2007) 3286
9. B. Karami, M. Montazerozohori, M. H. Habibi, Molecules 10 (2005) 1358
0. R. Hosseinzadeh, M. Tajbakhsh, H. Khaledi, K. Ghodrati, Monatsh. Chem. 138 (2007)
8
71
21. H. Golchoubian, F. Hosseinpoor, Catal. Commun. 8 (2007) 697
22. A. Corma, T. Rodenas, M. J. Sabater, Chem. Sci. 3 (2012) 398.
23. M. M. Hashemi, Z. Karimi-Jaberi, Monatsh. Chem. 135 (2004) 41.
24. A. Cervilla, A. Corma, V. Fornes, E. Llopis, P. Palanca, F. Reyy, A. Ribera, J. Am. Chem.
Soc. 116 (1994) 1595.
2
2
5. S. P. Mardur, G. S. Gokavi, J. Iran. Chem. Soc. 7 (2010) 441
6. A. Hasaninejad, M. A. Zolfigol, G. Chehardoli, M. Mokhlesi, J. Serb. Chem. Soc. 75
(
2010) 307
7. M. A. Zolfigol, P. Salehi, S. E. Mallakpour, M. Torabi, Bull. Chem. Soc. Japan 76 (2003)
673
2
1
2
2
3
8. B. Karimi, D. Zareyee, J. Iran. Chem. Soc. 5 (2008) S103
9. G. Chehardoli, M. A. Zolfigol, Phosphorus Sulfur Silicon Relat. Elem. 185 (2010) 193
0. A. Ghorbani-Choghamarani, M. Hajjami, H. Goudarziafshar, M. Nikoorazm, S. Mallak-
pour, F. Sadeghizadeh, G. Azadi, Monatsh. Chem. 140 (2009) 607
1. A. Ghorbani-Choghamarani, M. Abbasi, Chin. Chem. Lett. 22 (2011) 114
2. H. Goudarziafshar, A. Ghorbani-Choghamarani, M. Nikoorazm, Z. Naserifar, Chin. J.
Chem. 27 (2009) 1801
3
3
3
3
3
3. A. Ghorbani-Choghamarani, M. Nikoorazm, H. Goudarziafshar, L. Shiri, Z. Chenani,
Bull. Korean Chem. Soc. 30 (2009) 972
4. A. Ghorbani-Choghamarani, H. Goudarziafshar, S. Rezaee, S. S. Mortazavi, Chin. Chem.
Lett. 20 (2009) 415
5. A. Ghorbani-Choghamarani, M. A. Zolfigol, M. Hajjami, S. Rastgoo, S. Mallakpour, Lett.
Org. Chem. 7 (2010) 249
3
3
3
3
6. A. Ghorbani-Choghamarani, S. Sardari, Chin. J. Catal. 31 (2010) 1347
7. R. Ozen1, F. Aydin, Monatsh. Chem. 137 (2006) 307
8. A. R. Pourali, M. Ghanei, Bull. Korean Chem. Soc. 27 (2006) 1674
9. M. A. Zolfigol, Tetrahedron 57 (2001) 9509.
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