Basic Al2O3 as an efficient heterogeneous reagent for the synthesis of symmerical dialkyl trithiocarbonates

Article abstract of DOI:10.1080/00397910701861198

This work deals with reaction of alkyl halides with carbon disulfide in the presence of basic alumina as heterogeneous and reusable reagent. It afforded symmetrical dialkyl trithiocarbonate in moderate to excellent isolated yields. Reaction of 1,2-dichloro ethane with carbon disulfide also proceeded in a similar manner to give a five-membered cyclic trithiocarbonate without formation of any polymeric by-product. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397910701861198

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Basic Al2O3 as an Efficient Heterogeneous
Reagent for the Synthesis of Symmerical
Dialkyl Trithiocarbonates
Ali Reza Kiasat a , Foad Kazemi b & Ali Savari a
a Faculty of Sciences, Chemistry Department , College of Science, Shahid
Chamran University , Ahvaz, Iran
b Institute for Advanced Studies in Basic Sciences (IASBS) , Zanjan, Iran
Published online: 12 Mar 2008.
To cite this article: Ali Reza Kiasat , Foad Kazemi & Ali Savari (2008) Basic Al2O3 as an Efficient
Heterogeneous Reagent for the Synthesis of Symmerical Dialkyl Trithiocarbonates, Synthetic Communications:
An International Journal for Rapid Communication of Synthetic Organic Chemistry, 38:7, 1057-1063, DOI:
10.1080/00397910701861198
To link to this article: http://dx.doi.org/10.1080/00397910701861198
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Synthetic Communicationsw, 38: 1057–1063, 2008
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910701861198
Basic Al2O3 as an Efficient Heterogeneous
Reagent for the Synthesis of Symmerical
Dialkyl Trithiocarbonates
Ali Reza Kiasat,1 Foad Kazemi,2 and Ali Savari1
1Faculty of Sciences, Chemistry Department, College of Science, Shahid
Chamran University, Ahvaz, Iran
2Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
Abstract: This work deals with reaction of alkyl halides with carbon disulfide in the
presence of basic alumina as heterogeneous and reusable reagent. It afforded symmetri-
cal dialkyl trithiocarbonate in moderate to excellent isolated yields. Reaction of
1,2-dichloro ethane with carbon disulfide also proceeded in a similar manner to give
a five-membered cyclic trithiocarbonate without formation of any polymeric by-
product.
Keywords: Basic alumina, cyclic trithiocarbonate, symmetrical dialkyl trithiocarbonate
Trithiocarbonate compounds constitute an important class of organosulfur
compounds that have been used as intermediates for various applications,
especially as pesticides, insecticides, and nematocides in agriculture[1] and
as lubricating additives.[2] In addition to reported insecticidal and fungicidal
activities[3] for several members of the class of organic trithiocrabonates,
recently the successful appllication of dibenzyl trithiocarbonate in the
living/controlled free-radical polymerization under 60Co g-irradiation was
reported.[4]
Received in the U.K. March 15, 2007
Address correspondence to Ali Reza Kiasat, Faculty of Sciences, Chemistry Depart-
ment, College of Science, Shahid Chamran University, Ahvaz 61357-4-3169, Iran.
E-mail: akiasat@scu.ac.ir
1057

1058
A. R. Kiasat, F. Kazemi, and A. Savari
Some procedures for the synthesis of trithiocarbonates have been
developed that employ reaction of thiols with thiophosgene,[5] chlorodithio-
formates,[1] or carbon disulfide and alkyl halides under basic conditions.[6]
Another method that appears to be the most widely used involves dialkylation
of trithiocarbonate anion with alkyl halides in a two-phase system using an
onium salt as a phase-transfer agent.[3] In 1995, a report by Leung et al.[7]
showed that the reaction of alkyl halides, granulated KOH, and carbon
disulfide in anhydrous THF occurs smoothly to give symmetrical trithiocarbo-
nates without requiring the addition of a phase-transfer catalyst (PTC). Very
recently a novel procedure for preparation of symmetrical dialkyl trithiocarbo-
nates was reported.[8] In this method, alkyl halide was reacted with an equiv-
alent of carbon disulfide and cesium carbonate in polar aprotic solvents. Most
of these methods have at least one of the following drawbacks: (1) long
reaction times, (2) low yields of products, (3) difficulty in separating
product from the original reagent and PTC, (4) necessary presence of a
PTC, (5) use of aqueous media, (6) use of toxic chemicals such as alkane
thiols and thiophosgene, (7) use of an inert atmosphere, and (8) unavailability
of the reagents. Therefore the introduction of a new synthetic method for prep-
aration of dialkyl trithiocarbonates is of practical importance.
Alumina (Al2O3) is a key industrial material with numerous applications
in refining and petrochemistry.[9] This metal oxide is widely used industrially
as filler, adsorbent, drying agent, catalyst, catalyst support, and reagent.
g-Alumina is the transition alumina with a basic property most commonly
utilized to carry out surface organic chemistry.[10,11] In contrast to clays and
zeolites, this material does not contain accessible channels or cavities and
shows a large surface area and highly porous exteriors available to substrates.
As previously reported, the trithiocarbonate anions CS232 is prepared by
treating ammonium sulfide, strong aqueous ammonia, alkali-metal sulfide,
or aqueous alkali-metal hydroxide with carbon disulfide.[12] To increase the
yield and reactions rate, a PTC has often been used to promote the reactions
in two-phase systems.[3] Recently, we reported in a short communication
the one-pot synthesis of symmetrical dialkyl trithiocarbonates directly from
CS2 and alkyl halides using a commercially available hydroxide form of an
anion exchange resin.[12] The remarkable ability of the basic alumina to
promote the various reactions[13–15] together with reported insecticidal and
fungicidal activites of symmetrical dialkyl trithiocarbonate gave us impetus
for planning syntheses of various types of symmetrical trithiocarbonates in
a one-pot procedure using basic alumina as a cheap, heterogeneous, and
Scheme 1.

Basic Al2O3 as Heterogeneous Reagent
1059
reusable reagent. Thus, several symmetrical dialkyl trithiocarbonates were
easily prepared by simple mixing of alkyl halides or tosylates with suspension
of basic alumina in CS2 (Scheme 1).
This article shows that this solid base is able to facilitate the generation of
the trithiocarbonate anion. It is supported by the fact that benzyl chloride
(1 mmol), as a model compound in the presence of basic alumina (2 g) and
in CS2 as solvent and the only sulfur-containing reactant, was easily
converted to the corresponding dibenzyl trithiocarbonate under reflux con-
ditions. A set of experiments on the preparation of dibenzyl trithiocarbonate
showed that the addition of more than 2 g of basic alumina to the reaction
mixture (1 mmol of benzyl chloride in 10 ml of CS2) does not produce an
appreciable increase in the reaction rate, moreover, the conversion of the
starting material to the product is not complete even for prolonged reaction
times when the alumina proportion is less than 1.5 g. It is worth noting that
an increase in reactivity is observed when the required alumina was added
to the reaction mixture in two portions.
To establish the generality and applicability of this method, various
primary, secondary, allylic, and benzylic halides and some tosylates were
subjected to the same reaction conditions to furnish the corresponding sym-
metrical dialkyl trithiocarbonates in moderate to excellent isolated yields
(Table 1). As expected, the absolute regioselectivity was observed for the
case of 2-chlorobenzyl alcohol, and the only benzylic site was attached by
transient CS232 species. A notable point of this method is that in case the
alkyl halide or tosylate is not soluble in CS2, it has been necessary to carry
out the reaction in the presence of a few drops of THF.
Contrary to previous reports on the preparation of cyclic trithiocarbo-
nates,[16] our procedure provides excellent yields of 1,3-dithiolane-2-thione
from 1,2-dichloroethane without formation of any polymeric by-product. An
attempt to totally convert 1,2-dichloroethane to 1,3-dithiolane-2-thione
failed, and yield of the product after evaporation of intact 1,2-dichloroethane
and CS2 was only 48%. It is also worth mentioning that the nature of the
leaving group has a considerable effect on the reaction rate. The order of reac-
tivity for different substrates is ROTs . RI . RBr. RCI. The basic alumina
can be reused several times without loss of activity. The alumina, recovered by
filtration and washed with methanol, has been reused four times to convert
benzyl chloride to the dibenzyl trirhiocarbonate, affording the corresponding
trithiocarbonate in 85%, 82%, 81%, and 82% yield, respectively.
In summary, this article shows a simple and efficient general access to
pure symmetrical trithiocarbonates. Basic alumina, which has been used
here for the first time for such conversion, is inexpensive and commercially
available. Another interesting behavior of alumina is that it can be reused
after simple washing with methanol. The reactions are remarkably clean,
and no chromatographic separation is necessary to get the spectrally pure
compounds except in a few cases (Table 1, entries 5 and 13) where some
starting materials remained because the conversion was less than 100%.

Table 1. Conversion of alkyl halides and tosylates to the corresponding dialkyl trithiocarbonates using basic alumina
Time
(h)
Yield
(%)
Number
1
Starting material
Products
4
85
2
6
92
3
4
5
15
30
5
95
88
79
6
CH3I
2
44

7
CH3CH2CH2CH2OTs
2
88
8
9
CH3CH2CH2CH2I
CH3CH2CH2CH2Br
2.5
3.5
79
80
10
11
CH3CH2CH2CH2Cl
6
4
74
44
CH2 ¼ CHCH2Cl
12
13
ClCH2CH2Cl
4
7
48
78
CH3(CH2)6CH2-OTs
14
15
88
Notes. All reactions were carried out in refluxing carbon disulfide. Dialkyl trithiocarbonates were identified by their IR
and NMR spectra and also by comparison of their other physical data with those reported.[12]

1062
A. R. Kiasat, F. Kazemi, and A. Savari
EXPERIMENTAL
Alkyl halides and tosylates were from Fluka and Merck or prepared in our lab-
oratory from corresponding alcohols according to known procedures.[17] All
products are known compounds and are identified by comparison of their
physical and spectral dat (IR and NMR) with those previously reported.[12]
Caution: care should be taken in using CS2 because of its toxicity and low
flash point; therefore, all of the reactions must be carried out under a
powerful laboratory fume hood.
General Procedure for the Synthesis of Dialkyl Trithiocarbonates
using Basic Alumina
To the suspension of basic Al2O3 (1 g) in carbon disulfide (10 ml), alkyl
halide or tosylate (1 mml) was added (in cases where alkyl halide or
tosylate was not soluble in CS2, a few drops of THF were added to the
reaction mixture). The reaction mixture was stirred under reflux conditions.
In this case, the yellow color often developed immediately and darkened
with progress of the reaction. After about 1 h, additional basic alumina
(1 g) was added to the reaction mixture and stirred under reflux conditions.
The progress of the reaction was followed by thin-layer chromatography
(TLC) (CCI4). On completion of the reaction, the mixture was filtered
and washed with carbon disulfide or THF. The filtrate was dried over
anhydrous sodium sulfate, and the solvent was evaporated under reduced
pressure to affored the pure products (TLC, 1H NMR) in 44–95%
isolated yields.
ACKNOWLEDGMENTS
Partial support for this work by Chamran University Research Council is
gratefully acknowledged.
REFERENCES
1. Degani, L.; Fochi, R.; Gatti, A.; Regondi, V. Phase transfer synthesis of symmetri-
cal and unsymmetrical dialkyl trithiocarbonates. Synthesis 1986, 894–899 and
references cited therein.
2. Bashour, J. T U.S. Patent 2676129, Chem. Abstr. 1954, 48, 8472i.
3. Sugawara, A.; Hasegawa, K.; Suzuki, K. I.; Takahashi, Y.; Sato, R. Convenient
synthesis of alkanediyl bis(alkyltrithiocarbonate)s from alkanedithiols with alkyl
halides and carbon disulfide in the presence of phase transfer catalyst. Bull.
Chem. Soc. Jpn 1987, 60, 435–437.

Basic Al2O3 as Heterogeneous Reagent
1063
4. Bai, R. K.; You, Y. Z.; Pan, C. Y. Co-60 gamma-irradiation-initiated “living” free-
radical polymerization in the presence of dibenzyl trithiocarbonate. Macromol.
Rapid Commun. 2001, 22, 315–319.
5. Duus, F. Comprehensive Organic Chemsitry; Barton, D. and Ollis, W. D., Eds.;
Pergamon: New York, 1979, Vol. 3, p. 342.
6. Sugawara, A.; Shirahata, M.; Sato, S.; Sato, R. One pot synthesis of alkyl aryl
trithiocarbonates from benzenethiols, alkyl halides, and CS2 with a phase
transfer catalyst. Bull. Chem. Soc. Jpn. 1984, 57, 3353–3354.
7. Leung, M.; Hsieh, D. T.; Lee, K. H.; Liou, J. C. A novel one-step synthesis of sym-
metrical dialkyl trithiocarbonates. J. Chem. Res. Synop. 1995, 478–479.
8. Aoyagi, N.; Ochiai, B.; Mori, H.; Endo, T. Mild and efficient one-step synthesis of
trithiocarbonates using minimum amount of CS2. Synlett 2006, 636–638.
9. Digne, M.; Sautet, P.; Raybaud, P.; Euzen, P.; Toulhoat, H. Use of DFT to achieve
a rational understanding of acid-basic properties of gamma-alumina surface.
Journal of Catalysis 2004, 226, 54–68.
10. Kabalka, G. W.; Pagni, R. M. Organic reactions on alumina. Tetrahedron 1997, 53,
7999–8065.
11. Parks, G. A. Isoelectric points of solid oxides, solid hydroxides and aqueous
hydroxo complex systems. Chem. Rev. 1965, 65, 177–198.
12. Tamami, B.; Kiasat, A. R. Synthesis of symmetrical dialkyl trithiocarbonates using
a polymer supported system. J. Chem. Res., Synop. 1998, 454.
13. Satya, P.; Puja, N.; Rajive, G. PhCOCl-Py/basic alumina as a versatile reagent for
benzoylation in solvent-free conditions. Molecules 2003, 8, 374–380.
14. Ballini, R.; Clemente, R. R.; Palmieri, A.; Petrini, M. Conjugate addition of indoles
to nitroalkenes promoted by basic alumina in solventless conditions. Adv. Synth.
Catal. 2006, 348, 191–196.
15. Ballini, R.; Barboni, L.; Fiorini, D.; Giarlo, G.; Palmieri, A. One-pot synthesis of
3-alkyl-2,4-dinitrocyclohexanols, under solventless conditions using basic
alumina. Green Chem 2005, 7, 828–829.
16. Lee, A. W. M.; Chan, W. H.; Wong, H. C. One pot phase transfer synthesis of
trithiocarbonates from CS2 and alkyl halides. Synth. Commun. 1988, 18,
1531–1536.
17. Vogel, A. I. Textbook of Practical Organic Chemsitry, 4th edn.; ELBS and
Longman: London, 1978.