Zeolite H-Sdusy Powder (Cbv720) as a Recyclable Catalyst for an Efficient Thiocyanation of Aromatic and Heteroaromatic Compounds in Acetonitrile

Article abstract of DOI:10.1080/10426507.2014.978322

Thiocyanation of various aromatic and heteroaromatic compounds has been studied using Zeolite H-SDUSY Powder (CBV720) as catalyst and ammonium thiocyanate (NH₄SCN) as thiocyanation reagent in acetonitrile medium. Reactions afforded good yields of products under stirred conditions at reflux temperature. Reactions underwent enhancements under sonication (using an ultrasonic probe of 24 kHz frequency) and microwave irradiation. The use of ultrasound decreased the reaction times from (7-12 h) to few minutes (70-150 min). The use of microwave irradiation much more effectively enhanced the reaction rates than sonicated and conventional protocols used in this study.

Full text of DOI:10.1080/10426507.2014.978322

This article was downloaded by: [The University of British Columbia]
On: 22 November 2014, At: 04:34
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,
37-41 Mortimer Street, London W1T 3JH, UK
Phosphorus, Sulfur, and Silicon and the Related
Elements
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/gpss20
Zeolite H-SDUSY Powder (CBV720) as a Recyclable
Catalyst for an Efficient Thiocyanation of aromatic and
heteroaromatic compounds in acetonitrile
a
a
a
a
V. Sudhakar Chary , G. Krishnaiah , M. Satish Kumar & K. C. Rajanna
a
Department of Chemistry, Osmania University, Hyderabad-500 007, T.S. (India)
Accepted author version posted online: 14 Nov 2014.
To cite this article: V. Sudhakar Chary, G. Krishnaiah, M. Satish Kumar & K. C. Rajanna (2014): Zeolite H-SDUSY Powder
CBV720) as a Recyclable Catalyst for an Efficient Thiocyanation of aromatic and heteroaromatic compounds in acetonitrile,
(
Phosphorus, Sulfur, and Silicon and the Related Elements, DOI: 10.1080/10426507.2014.978322
To link to this article: http://dx.doi.org/10.1080/10426507.2014.978322
Disclaimer: This is a version of an unedited manuscript that has been accepted for publication. As a service
to authors and researchers we are providing this version of the accepted manuscript (AM). Copyediting,
typesetting, and review of the resulting proof will be undertaken on this manuscript before final publication of
the Version of Record (VoR). During production and pre-press, errors may be discovered which could affect the
content, and all legal disclaimers that apply to the journal relate to this version also.
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained
in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no
representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the
Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and
are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and
should be independently verified with primary sources of information. Taylor and Francis shall not be liable for
any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever
or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of
the Content.
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any
form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://
www.tandfonline.com/page/terms-and-conditions

ACCEPTED MANUSCRIPT
Zeolite H-SDUSY Powder (CBV720) as a Recyclable Catalyst for an Efficient
Thiocyanation of aromatic and heteroaromatic compounds in acetonitrile
V. Sudhakar Chary, G. Krishnaiah, M. Satish Kumar, K. C. Rajanna*
Department of Chemistry, Osmania University, Hyderabad-500 007, T.S. (India)
*
Author for Correspondence: kcrajannaou@yahoo.com
Abstract: Thiocyanation of various aromatic and heteroaromatic compounds has been studied
using Zeolite H-SDUSY Powder (CBV720) as catalyst and ammonium thiocyanate (NH SCN)
4
as thiocyanation reagent in acetonitrile medium. Reactions afforded good yields of products
under stirred conditions at reflux temperature. Reactions underwent enhancements under
sonication (using an ultrasonic probe of 24 kHz frequency) and microwave irradiation. The use
of ultrasound decreased the reaction times from (7 -12h) to few minutes (70-150 min). The use
of microwave irradiation much more effectively enhanced the reaction rates than sonicated and
conventional protocols used in this study.
X
X
NH SCN/ Zeolite-Y (CBV-720)
4
SCN
Acetonitrile
Y
Y
i) Conventional; ii) Sonication; iii) Microwave
Where X = OH, NH ; Y= EWG or EDG
2
Keywords: Zeolite H-SDUSY(CBV720);ammoniumthiocyanate; thiocyanation; organic
compounds; sonication; microwave irradiation; rate accelerations
1
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
INTRODUCTION
The electrophilic thiocyanation of aromatic and heteroaromatic compounds is an important
1
carbon-heteroatom bond formation reaction in organic synthesis . Thiocyanate is a versatile
2
synthon that can be readily transferred to pharmaceutically important functional groups such as
sulfide, aryl nitrile, thiocarbamate, and thionitrile to produce drugs. This versatile nature of
thiocyanate group attracted several groups of workers, who embarked on taking up thiocyanation
3
-5
of aromatic and heteroaromatic compounds under varied conditions in order to explore user-
6
a
friendly methodologies. Oxidizing catalysts such as ceric ammonium nitrate (CAN) , ferric
6
b
6c
6d
6e
chloride (FeCl
3
) , Oxone , 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) , (HIO
3
) , iodine
6
f
6g
pentoxide (I
2
O
5
) , p-Toluenesulfonic acid (p-TSA) , have been recently employed for efficient
and regioselective thiocyanation of aromatic and heteroaromatic compounds in presence of
ammonium thiocyanate as reagent. Sajjadifar et al recently reported simple and highly efficient
7
catalytic protocols for thiocyanation of aromatic compounds using H
2
O
2
/KSCN and
H
5
IO
6
/KSCN in aqueous media.
An increasing demand for the design of catalysts, which can be easily separated from products
and recycled, is still the subject of investigation from green chemistry point of view. Micro and
mesoporous materials offer unique opportunities for heterogeneous catalysis by their large
surface area. Zeolites are a special class of aluminosilicates that contain silicate and aluminate
8
, 9
ions as backbones along with a few vacant positions in their structures . Because of the large
vacant spaces in three-dimensional structures, Zeolites give room for cations such as sodium and
calcium and molecules such as water. These spaces are interconnected and form long channels
and pores, which are of different sizes in different Zeolites. Even though several Zeolites have
2
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
found their use as efficient catalysts, not much work appears to have been reported on Zeolite H-
SDUSY Powder (CBV720). These reasons together with the versatility of SCN functionality
stimulated us to take up the Zeolite H-SDUSY Powder (CBV720)/ ammonium thiocyanate
(
NH SCN) triggered thiocyanation of aromatic and hetero aromatic compounds. The control
4
experiments of thiocyanation did not proceed even at elevated temperatures and after 24 h of
reaction time in dichloromethane, dichloroethane, and toluene. Even in acetonitrile medium, also
the reactions were sluggish. Therefore, the authors took up the present study under sonication
and microwave irradiation for effective thiocyanation encouraged by earlier success reports and
1
0-12
13-15
advantages of ultrasound assisted
, and microwave assisted chemical reactions
.
RESULTS AND DISCUSSION
Aromatic compounds upon treatment with (0.10 mol) ammonium thiocyanate in presence of
Zeolite-Y (CBV-720) as a catalyst in acetonitrile medium afforded thiocyanate derivatives in
very good yield (Scheme-1). Nature of solvent plays an important role in altering the rate of a
reaction, therefore, we have studied the thiocyanation of phenol using it as a model substrate in
various solvents such as chloroform, dichloromethane (DCM), dichloroethane (DCE), n-hexane,
tetra hydro furan (THF)and acetonitrile (MeCN) at room temperature. Another important aspect
is to optimize the reaction conditions i.e., the concentrations of catalyst (Zeolite-Y), substrate
and NH
n-hexane media, even though a wide concentration of Zeolite-Y (5 to 100 mg i.e., 0.26-5.20 mol
) is used as catalyst. Nevertheless, the reaction went much more smoothly in ACN with small
amount of catalyst (0.26-mol percentage Zeolite-Y), 1.0 millimolar substrate and 2.0 millimolar
4
SCN. Practically no trace of product was observed in chloroform, DCM, DCE, THF and
%
of NH
4
SCN. Therefore, reactions with other substrates were studied using 0.26 mol percentage
3
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
(
or 5.0 mg) of Zeolite-Y. A wide range of active, moderately active, and non-active aromatic
and heterocyclic compounds were taken for Zeolite-Y triggered thiocyanation under
conventional and non-conventional conditions and the corresponding results are presented in
Table 1.
[
Insert Table 1]
Even though the presented data reflects that thiocyanation reactions require longer reaction times
are (7 to 12 h), it is of interest to note that para substituted compounds underwent thiocyanation
only at the ortho position, while ortho substituted compounds afforded the para derivative in
very good yield. It is also of interest to note that aromatic hydrocarbons such as α-
methoxynaphthalene underwent smooth thiocyanation with good yields. Since the reactions
required longer reaction times (7-12h) under convention conditions, we have tried ultrasonically
assisted and microwave assisted methods to enhance the rates of the reactions. In the recent past
ultrasonically assisted (USAR) and microwave-assisted (MWAR) reactions have received
considerable attention because of their immense importance to promote and enhance a broad
1
0-15
spectrum of synthetic organic reactions
. These techniques have become helpful to chemists
to overcome many of the difficulties associated with conventional reactions related to their
environmental shortcomings. All the reactions in the present study underwent dramatic rate
enhancements, and maintained their desirable selectivity and ease of experimental manipulation.
The reaction times were reduced from 7-12 h (under conventional conditions) to about 70 – 90
min in USA reactions and about 1-4 min in MWA reactions.
Rate accelerations of the ultrasonically assisted thiocyanation reactions (USNR) in the present
study are due to cavitation, a physical process that creates, enlarges, and implodes gaseous and
4
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
1
0-13
vaporous cavities in an irradiated liquid
. Cavitation is a process in which mechanical
activation destroys the attractive forces of molecules in the liquid phase. Applying ultrasound,
compression of the liquid is followed by rarefaction (expansion), in which a sudden pressure
drop forms small, oscillating bubbles of gaseous substances. These bubbles expand with each
cycle of the applied ultrasonic energy until they reach an unstable size; they can then collide
and/or violently collapse. Cavitation induces very high local temperatures in the liquid and
enhances mass transfer.
1
4,15
On the other hand the observed rate and yield enhancements in MWA reactions
is probably
due to a combination of thermal effects, arising from the heating rate, superheating or ‘‘hot
spots’’ and the selective absorption of radiation by polar substances which ultimately causes bulk
activation of molecules. It is important to note that the rate of the reaction has a direct
dependence on the fraction of activated/energized species. We have tried to compare the results
obtained in the present study with earlier reports on thiocyanation and presented the data in
table-2. These results are found to be in comparable range with earlier reports. More particularly
the reaction times under microwave conditions are lesser than earlier protocols indicating that the
present methodology is also a sincere effort in the development of new eco-friendly protocol for
thiocyanation of aromatic compounds.
Conclusions
In summary, the authors have developed Zeolite H-SDUSY Powder (CBV720) /ammonium
thiocyanate triggered electrophilic thiocyanation of aromatic and heteroaromatic compounds in
acetonitrile medium under conventional, sonication and micro wave irradiation. These newly
developed methods have several advantages such as reusability of the catalyst, simple workup
5
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
procedure, good selectivity, short reaction times and high product yields. The longer reaction
times of conventional methods (7-12 h) were remarkably reduced to about (70 – 150) min in
sonicated and (1-4) min in MW assisted reactions.
EXPERIMENTAL
Materials and methods
Chemicals were obtained from S.D fine Chemicals (India), Avra fine Chemicals (India), and
Aldrich Chemical Company and used without further purification. CBV720 (Si/Al bulk = 13)
was purchased from Zeolyst International. It was supplied in H-form. A detailed characterization
9
of this catalyst is well documented in literature and effectively used as a catalyst .
A typical procedure for thiocyanation of organic compounds
In a typical experiment, zeolite catalyst (0.26-0.52 mol percentage), substrate (0.1 mol), and
ammonium thiocyanate (0.2 mol) in MeCN (20 mL) were taken in a reaction flask and constantly
stirred for about 10 -12 h at reflux temperature, depending on the nature of the substrate. The
progress of the reaction was monitored by TLC (ethyl acetate: n-hexane 1:9). After completion
of the reaction, the reaction mixture was treated with DCE, dried over anhydrous Na
2
SO , and
4
1
concentrated to obtain the product. The products were identified by IR, H NMR and MS
spectra. IR spectra showed the characteristic peaks of the –SCN group between 2120 and 2150
-1
-1
cm and the C–S stretching between 650 and 750 cm . The results agreed well with literature
3
-7.
reports
Typical Procedure for ultrasonic assisted (USAR) thiocyanation of organic compounds
Method of thiocyanation under sonication is similar to the one described in the preceding
section. The reaction vessel containing zeolite catalyst (0.26-0.52 mol percentage), substrate
6
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
(
0.1 mol), and ammonium thiocyanate (0.2 mol) in MeCN (20 mL) was placed in a Sonicator
and the progress of the reaction was monitored by TLC. After completion of the reaction, the
reaction mixture was filtered, washed with water and worked up as described in the conventional
1
approach. All products are characterized by comparison of their IR, H-NMR and Mass spectra
and with their physical data.
Procedure for Microwave Assisted (MWAR) thiocyanation of organic compounds
A CEM microwave reactor was used, which was equipped with temperature, pressure, and power
control units. An oven-dried microwave vial was charged with a mixture containing zeolite
catalyst (0.26-0.52 mol percentage), substrate (0.1 mol), and ammonium thiocyanate (0.2 mol) in
silica gel slurry, and irradiated in a microwave (power input 140 W) at 150°C for few minutes.
After completion of the reaction, as ascertained by TLC, the reaction mixture was treated with
sodium bicarbonate; the organic layer was diluted with dichloromethane (DCM), and separated
from the aqueous layer. The crude product mixture was purified by recrystallization with an
ethyl acetate -DCM mixture in 2:3 ratios. The purity was checked with TLC. The products were
identified by characteristic spectroscopic data.
Acknowledgments
The authors are thankful to the CSIR for financial assistance in the form of a fellowship awarded
to Sudhakar Chary. The authors are indebted to Professor T. Navaneeth Rao (Former Vice-
Chancellor, O.U), Professor P. K. Saiprakash (Former Science Faculty Dean, O. U), Head,
Department of Chemistry, (O. U) and Principal, Nizam College for constant encouragement and
facilities.
7
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
REFERENCES
1
. (a) Guy, R. G. In: The Chemistry of Cyanates and Their Thio Derivatives, Edited by S. Patai,
John Wiley & Sons: New York, NY, USA, 1977, part 2, pp. 819–886;.(b) Wood, V In:
Organic Reactions 3, Wiley: New York, 1967, pp. 240–266; (c) A. A. Newman, In:
Chemistry and Biochemistry of Thiocyanic acid and its Derivatives, first ed., Academic
Press, USA, 1975,
pp. 222-255.
2
. (a) Sajjadifar, S.; Hosseinzadeh, H.; Ahmadaghaee, S.; Rezaee Nezhad, E.; Karimian, S.
Phosphorus Sulfur Silicon Relat. Elem. 2014, 189, 333-342 (b) Zhang, Z. H.; Liebeskind, L.
S. Org. Lett. 2006, 8, 4331-4333. (c) Riemschneider, R.; Wojahn, F.; Orlick, G. J. Am. Chem.
Soc. 1951, 73, 5905-5907; (d) Riemschneider, R. J. Am. Chem. Soc. 1956, 78, 844-847; (e)
Lee, Y. T.; Choi, S. Y.; Chung, Y .K. Tetrahedron Lett. 2007, 48, 5673-5677. (f) Yadav, J.
S.; Reddy, B. V. S.; Shubashree.; Sadashiv, K. Tetrahedron Lett. 2004, 45, 2951-2954 (g)
Iranpoor, N.; Firouzabadi, H.; Khalili, D.; Shahin, R. Tetrahedron Lett. 2010, 51, 3508-3510
. (a) Yadav, J. S. ; Reddy, B. V. S.; Reddy, U. V. S.; Chary, D. N. Synthesis. 2008, 1283-1287
3
(
b) Yadav, J. S. ; Reddy, B. V. S.; Gupta, M. K. Synthesis. 2004, 1983-1986. (c) Jiao, J.;
Nguyen, L. X.; Patterson, D. R.; Flowers II, R. A. Org. Lett. 2007, 9, 1323-1326. (d) Ju, Y.;
Kumar, D.; Varma, R. S. J. Org. Chem. 2006, 71, 6697-6700. (e) Iranpoor, N.; Firouzabadi,
H.; Akhlaghinia, B.; Azadi, R. Synthesis. 2004, 92-96. (f) Liu, Y. ; Xu, Y.; Jung, S. H.; Chae,
J.; Synlett. 2012, 23, 2663-2666. (g) Bhalerao, D. S.; Agamanchi, K. G. Synlett. 2007, 2952-
2
956 . (h) Beletskaya, I. P.; Sigeev, A. S.; Peregudov, A. S.; Petrovskii, P. V. Mendeleev
Commun. 2006,16, 250-251. (i) Barbero, M.; Degani, I.; Diulgheroff, N.; Dughera, S.; Fochi,
8
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
R. Synthesis. 2001, 585-590. (j) G. Wu,; Liu, Q.; Shen, Y.; Wu, W.; Wu, L. Tetrahedron
Lett. 2005, 46, 5831-5834.
4
. (a) Zolfigol, M. A.; Khazaei, A. ; Mokhlesi, M.; Vahedi, H.; Sajjadifar, S.; Pirveysian, M.
Phosp. Sulfur. Silic. Rel. Elem. 2012, 187, 295-304. (b) Wu, L.; Yang, X. Phosp. Sulfur.
Silic. Rel. Elem. 2012, 187, 748-753. (c) Iranpoor, N.; Firouzabadi, H.; Bahador, H.;
Jamalian, A. Phosphorus Sulfur Silicon Relat. Elem. 2010, 185, 1972-1978. (d) Wu, L.;
Chao, S.; Wang, X.; Yan, F. Phosphorus Sulfur Silicon Relat. Elem., 2011, 186, 304-310. (e)
Azadi, R.; Mokhtari, B. Oghabi, H.; Phosphorus Sulfur Silicon Relat. Elem. 2012, 187, 1377-
1
7
2
382. (f) Aghapour, G.; Asgharzadeh, A. Phosphorus Sulfur Silicon Relat. Elem. 2014, 189,
96-802. (h) Sharghi, H.; Nejad, A. H. Phosphorus Sulfur Silicon Relat. Elem. 2004, 179,
297-2305.
5
. (a) Wu, L.; Yang, Yan, F. J. Sulfur Chem. 2011, 32, 105–110. (b) Mokhtari, B.; Azhdari, A.;
Azadi, R. J. Sulfur Chem. 2009, 30, 585–589. (c) Iranpoor, N.; Firouzabadi, H.; Azadi, R. ;
Akhlaghinia, B. J. Sulfur Chem. 2005, 26, 133–137. (d) Awasthi, S.; Narasimha Rao, A.;
Ganesan, K. J. Sulfur Chem. 2009, 30, 513–517. (e) Karimi Zarchi, M. A.; Banihashemi, R.;
J. Sulfur Chem. 2014, 35, 458–469.(f) Venkatesham, N.; Rajendar Reddy, K.; Rajanna, K.
C.; Veerasomaiah. P. J. Sulfur Chem., 2014, 35, 606-612.
6
. (a) Nair, V.; George, T. G.; Nair, L. G.; Panicker, S. B. Tetrahedron Lett., 1999, 40,1195–
1
196,. (b) Yadav, J. S. ;. Reddy, B. V. S.; Krishna, A. D.; Suresh Reddy, Ch.; Narsaiah. A. V.
Synthesis. 2005, 6,961-964. (c) Wu, G.; Liu, Q.; Shen, Y.; Wu, W. ; Wu. L. Tetrahedron
Lett. 2005, 46, 5831–5834. (d) Memarian, H. R.; Mohammadpoor, B. I.; Nikoofar , K.
Ultrasonics sonochem. 2008, 15, 456-62. (e) Mahajan, U. S.; Krishnacharya. G. A. Synth.
9
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Commun. 2009, 39, 2674-2682. (f) Wu, J.; Wu, G; Wu, L. Synth. Commun. 2008, 38, 2367–
2
373. (g) Das, B.; Satya Kumar. A. Synth. Commun. 2010 40, 337-341.
. Khazaei, A.; Zolfigol, M. A.; Mokhlesi, M.; Panah, F. D.; Sajjadifar, S. Helv. Chim. Acta,
012, 95, 106–114.
7
8
2
. (a) Breck, D. W.; Zeolite Molecular Sieves, Wiley, New York, (1974). (b) Dyer, A. ; An
Introduction to Zeolite Molecular Sieves, Wiley, New York, (1988). (c) K. B. Yoon,
Electron- and charge-transfer reactions within Zeolites, Chem. Rev., 1993, 93, 321–339. (d)
Taira, N.; Saitoh, M. ; Hashimoto, S.; Rang Moon, H.; Yoon, K. B.; Photochem. Photobiol.
Sci, 2006 , 5, 822–827.
9
.
(a) Collignon, E.; Mariani, Moreno, S.; Remy, M.; Poncelet, G. J. Catal. 1997, 166 ,53-66;
(
b) Collignon, F.; Poncelet, G.; J. Catal. 2001, 202 ,68-77; (c) Denayer, J.F.M.; Martens,
J.A.; Jacobs, P.A.; Thybaut, J.W.; Marin, G.B. Baron, G.V. Appl. Catal. A. 2003, 246, 17-
2
8;(d) Remy, M.J.; Stanica, D.; Poncelet, G.; Feijen, E.J.P.; Grobet, P.J.; Martens, J.A.;
Jacobs, P.A. J. Phys. Chem. 1996, 100, 12440-12447; (e) Craciun, I.; Reyniers, M.F.; Marin,
G. B.; J. Mol. Cat. A: Chem. 2007, 277,1- 14.
1
1
0. (a) Suslick, K. S.; Goodale, J. W.; Schubert, P. F.; Wang, H.H.; J. Am. . Soc. 1983,105,
781-5785; (b) Suslick, K. S. Science. 1990, 247, 1439-45
1. (a) Mason, T.J.; Lorimer, J.P. Chem. Soc. Rev. 1987, 16, 239-
5
2
74; (b) C. Einhorn, J. Einhorn, J. L. Luche, Synthesis 1989, 787-813 (c) T. J. Mason, J.L.
Luche, R. Van Eldik, C.D. Hubband (Eds.),Chemistry Under Extreme or Non-Clasical
Conditions, Spectrum, Heidelberg, Wiely, New York, 317, (1997).
1
0
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
1
1
2. Memarian, H.R.; Baltork, I.M.; Nikoofar, K. Ultrasonics Sonochem. 2008, 15, 456–462.
3. (a) Caddick,S. Tetrahedron. 1995, 51, 10403-10432; (b) Lidström, P.;Tierney, J.; Wathey,
B.; Westman,J. Tetrahedron. 2001, 57, 9225- 9283
1
1
4. Roberts, B. A.; Strauss, C. R. Acc. Chem. Res. 2005, 38, 653-661.
5. Hoz, A.; D. Ortiz, A.D.; Moreno, A. Chem. Soc. Rev. 2005, 34, 164 - 178
1
1
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Table 1: Ultrasonic and microwave assisted thiocyanation of certain aromatic and
heteroaromatic compounds using (Zeolite H-SDUSY Powder (CBV720) /NH
4
SCN) in
acetonitrile
3
-7
S. Substrate
N
Product
Conventional
Sonication
MWAR
R. T (hrs)
Yield R. T (min) Yield R. T
Yield
(%)
72
(
65
%)
(%)
68
(sec)
55
1
2
Phenol
2-Thiocyanato
phenol
2-Methyl-4-
thiocyanato
phenol
10
8
90
70
o-Cresol
67
72
72
70
50
60
50
75
78
72
3
4
m-Cresol
3-Methyl-4-
thiocyanato
phenol
4-Bromo-2-
thiocyanato-
phenol
9
9
70
66
75
70
4-Bromo
phenol
5
6
Aniline
4-Thiocyanato
aniline
2-Chloro- 4-
thiocyanato
aniline
10
9
75
68
90
70
78
71
70
60
80
74
o-Chloro
aniline
7
m-Methoxy-
aniline
3-Methoxy-4-
thiocyanato-
aniline
10
60
100
65
90
70
8
9
N-Methyl
aniline
N,N-Dimethyl 4-Thiocyanato-
4-Thiocyanato-
N-methyl aniline
11
13
68
66
120
150
72
72
120
240
78
80
aniline
N,N-dimethyl
aniline
1
1
0 Furan
2-Thiocyanato
furan
7
8
74
65
50
80
78
72
40
60
80
75
1 Diphenylamine 4-Thiocyanato
diphenylamine
1
2
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
1
1
1
1
2 Indole
3-thiocyanato-
H-indole
8
8
8
8
70
75
85
80
70
70
70
70
72
74
86
78
60
60
60
60
76
77
86
79
1
3 1-Methyl-
indole
4 5-Bromo-
indole
5 2-Methyl-
Indole
1-Methyl-3-
thiocyanatoindole
5-Bromo-3-
thiocyanatoindole
2-methyl 3-
thiocyanato-
indole
1
1
1
6 Pyrrole
2-thiocyanato-
8
72
66
68
70
90
70
75
70
72
50
70
60
78
74
75
1
H-pyrrole
7 Thiophene
2-Thiocyanato
thiophene
1-Methoxy-4-
thiocyanato
naphthalene
10
12
8 1-Methoxy
naphthalene
1
3
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Table 2: Comparison of the isolated yields for the thiocyanation of Aniline to 4-thiocyanato
aniline with reported classical methods
Catalyst
Reaction
Time
Yield Reference
(%)
&
Conditions
CBV720/MW assisted reaction
P4VP-SCN
70 (sec)
80
Present work
o
8( min) 0-5 C 85
4(a)
3(h)
3(i)
3(j)
Aryldiazonium salt
Copper powder
--
--
84
56
90
1
-methyl-3-(2-(sulfooxy)ethyl)-1H- 7 (min)
imidazol-3-ium thiocyanate.
NH VO / MW assisted reaction
4
3
5 -7 min
80
5(f)
1
4
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
X
X
NH SCN/ Zeolite-Y (CBV-720)
4
SCN
Acetonitrile
Y
Where X = OH, NH ; Y= EWG or EDG
Y
2
NH SCN/ Zeolite-Y (CBV-720)
4
Acetonitrile
SCN
X
X
Where X = O, S, NH
i) Conventional; ii) Sonication; iii) Microwave
Scheme - 1: Zeolite-Y (CBV-720)/ NH SCN triggered Thiocyanation of Aromatic and HeterocyclicCompounds
4
1
5
ACCEPTED MANUSCRIPT