A facile synthesis of aryl thiocyanates using sodium perborate

Article abstract of DOI:10.1081/SCC-100105678

A simple and convenient synthesis of aryl thiocyanates in high yields using sodium perborate is described.

Full text of DOI:10.1081/SCC-100105678

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A FACILE SYNTHESIS OF ARYL THIOCYANATES USING
SODIUM PERBORATE
a
a
Vidyadhar K. Jadhav , Ravindra R. Pal , Prakash P. Wadgaonkar & Manikrao M.
b
Salunkhe
a
Department of Chemistry, The Institute of Science, 15, Madam Cama Road, Mumbai,
4
00 032, India
b
Department of Chemistry, The Institute of Science, 15, Madam Cama Road, Mumbai,
00 032, India
4
Version of record first published: 16 Aug 2006.
To cite this article: Vidyadhar K. Jadhav , Ravindra R. Pal , Prakash P. Wadgaonkar & Manikrao M. Salunkhe (2001): A
FACILE SYNTHESIS OF ARYL THIOCYANATES USING SODIUM PERBORATE, Synthetic Communications: An International Journal
for Rapid Communication of Synthetic Organic Chemistry, 31:19, 3041-3045
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SYNTHETIC COMMUNICATIONS, 31(19), 3041–3045 (2001)
A FACILE SYNTHESIS OF
ARYL THIOCYANATES USING
SODIUM PERBORATE
1
Vidyadhar K. Jadhav, Ravindra R. Pal,
1
2
Prakash P. Wadgaonkar, and
1
,
Manikrao M. Salunkhe *
1
Department of Chemistry, The Institute of Science,
5, Madam Cama Road, Mumbai 400 032, India
National Chemical Laboratory, Pune 411 008, India
1
2
ABSTRACT
A simple and convenient synthesis of aryl thiocyanates in high
yields using sodium perborate is described.
Thiocyanation of arenes is an important synthetic strategy for pre-
paration of aryl thiocyanates which provides attractive routes to many
1
,2
type of heterocyclic compounds having marked physiological activity.
Consequently, a variety of methods for the thiocyanation of arenes have
been reported in the literature ranging from Br , Pb(OAc) , MnO , CuSO /
2
4
2
4
6,7
3
metal thiocyanate, PhI(SCN) , polymer supported thiocyanogen ion,
,4
5
2
8
N-thiocyanato succinimide (NTS), mixture of [bis(acetoxy)iodo] benzene,
9
PhI(OAc) and KSCN, cerric ammonium nitrate/NH SCN,
10,11
CuBr2/
2
4
1
2
Al O -KSCN/SiO .
2
3
2
*
Corresponding author.
3
041
Copyright & 2001 by Marcel Dekker, Inc.
www.dekker.com

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3
042
JADHAV ET AL.
Table. Thiocyanation of Arenes

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ARYL THIOCYANATES
3043
Scheme 1.
Sodium perborate is an inexpensive, easily available, safe and easy to
handle oxidant. Sodium perborate has been used for a variety of oxida-
1
tion reactions. Recently we have prepared 1,2-benzisoxazole, N,N -diacyl
3
0
1
hydrazines andhalogenatedaromaticcompoundsusingsodiumperborate.
4
15
As an extension of our work on sodium perborate, we explored the possibility
of thiocyanation of arenes using sodium perborate and ammonium thio-
cyanate. Substituted aromatic and some heterocyclic compounds when trea-
ted with ammonium thiocyanate and sodium perborate in glacial acetic acid at
roomtemperaturegavethecorrespondingthiocyanatocompounds(Scheme 1).
The reaction worked well giving good to excellent yields of the product.
The results are summarized in table. It is observed that deactivated
rings i.e. nitrobenzene and non-activated ring i.e. benzene do not undergo
thiocyanation reaction even after 1 h at room temperature. Whereas, acti-
vated and active hetero aromatic rings undergoes thiocyanation reaction
smoothly. It is interesting to note that aniline undergoes thiocyanation with-
out affecting the amino group, possibly as thiocyanogen (SCN) is instantly
2
formed in situ. Therefore aniline undergoes thiocyanation without oxidation
under the experimental condition used. In case of styrene, epoxidation was
not observed under experimental condition used.
1
The products obtained were characterized by IR, H-NMR spectral
analysis and comparison of physical constants (melting point) with that of
authentic samples prepared as per reported procedure. IR spectra of thio-
ꢀ1
cyanato derivatives, shows characteristic absorption bands at 2140 cm
-SCN stretching).
(
EXPERIMENTAL
General Procedure for Thiocyanation Reaction
A solution of SPB (0.31 g, 2mmol) and NH SCN (0.08 g, 1.2mmol) in
4
glacial acetic acid (20 mL) was stirred at r.t. Immediately substituted aro-
matic compound (1 mmol) was added and the resulting mixture was stirred
at room temperature for 15 min. The completion of reaction was confirmed

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3
044
JADHAV ET AL.
by TLC (chloroform: petroleum ether 60–80). After completion of reaction,
water (50 mL) was added and the product was extracted by CH Cl2
2
(
(
3 ꢁ 25 mL). The organic layer was washed with H O (2 ꢁ 20 mL), dried
2
Na SO ), and concentrated under reduced pressure to get the product. It
2
4
was purified by short column chromatography on silica gel (60–120) using
chloroform: pet. Ether (60–80) as an eluent.
In conclusion, we have developed a facile, easy, and inexpensive
route to the synthesis of aryl thiocyanates mediated by sodium perborate.
The present procedures appear attractive due to its experimental simplicity
and generally high yields of the products.
REFERENCES
1
2
. Wood, J.L. Organic Reactions, Vol. 3, Chapter 6, 1947, 240.
. Guy, R.G. The Chemistry of cyanates and their thio derivatives, Part 2,
Patai S., Ed., Chapter 18, 1977, 819.
3
4
5
6
7
8
. Gardner, W.H.; Weinberger, H. Inorganic Synthesis, 1964, Vol. 1, 84.
. Kaufmann; Kuchler. Ber. 1934, 67, 944.
. Neu. Ber. 1939, 72, 1505.
. Nielsen, K.; Stensrud, T.; Bernateck, E. Acta. Chem. Scand. 1972, 26, 15.
. Chantal, C.; Rachid, E.G. Eur. Polym. J. 1988, 24, 2 1.
. Toste, F.D.; Stenfeno, V.D.; Still, I.W. J. Synth. Commun. 1995,
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5, 12 77.
. Mico, A.; Margarita, R.; Mariani, A.; Piancatelli, G. Chem. Commun.
997, 1237.
0. Nair, V.; George, T.G.; Nair, L.G.; Panicker, B. Tetrahedron Lett.
999, 40, 1195.
9
1
1
1
11. Nair, V.; Nair, L.G. Tetrahedron Lett. 1998, 39, 4585.
12. Suzuki, Y.; Kodomari, M. Chem. Lett. 1998, 1091.
13. Jadhav, V.K.; Deshmukh, A.P.; Wadagaonkar, P.P.; Salunkhe, M.M.
Synth. Commun. 2000, 30(8), 1521–1527.
14. Jadhav, V.K.; Wadagaonkar, P.P.; Salunkhe, M.M. J. Chinese Chem.
Soc. 1998, 45, 831–833.
15. Deshmukh, A.P.; Jadhav, V.K.; Padiya, K.J.; Salunkhe, M.M. J.
Chem. Res. (R) 1998, 828.
NOTE
Aryl thiocyanates are the intermediates for the synthesis of different
compounds particularly N- and S-heterocycles of marked physiological

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ARYL THIOCYANATES
3045
activity. We have developed a facile, easy, and inexpensive route to
the synthesis of aryl thiocyanates mediated by sodium perborate. The
present procedure appears attractive due to its experimental simplicity
and generally high yields of the products.
By considering the future application of sodium perborate as oxidising
agents in synthetic organic chemistry this communication needs rapid
publication.
Received in the Netherlands October 12, 2000

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