A novel synthesis of cyclic polythioethers using liquid-liquid phase-transfer catalysis

Article abstract of DOI:10.1080/10426500307887

The synthesis of cyclic polythioethers has been achieved by the reactions of dithiols with alkyl dihalides. Thiols are not only hard to handle owing to their unpleasant smell, but also they are easily oxidizable, thus it is not easy to obtain various dithiols. However, we have developed a procedure for the preparation cyclic polythioethers by the reaction of dithioiminium salts with alkyl dihalides using phase-transfer catalyst without the use of dithiols, and have examined the ion recognition of these compounds.

Full text of DOI:10.1080/10426500307887

This article was downloaded by: [Florida State University]
On: 21 October 2014, At: 22:22
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
A Novel Synthesis of Cyclic Polythioethers Using Liquid-
Liquid Phase-Transfer Catalysis
a
a
a
a
Toshio Takido , Masaharu Toriyama , Kazuhiro Ogura , Haruo Kamijo , Shigeyasu
a
a
Motohashi & Manabu Seno
a
Nihon University , Chiba, Japan
Published online: 27 Oct 2010.
To cite this article: Toshio Takido , Masaharu Toriyama , Kazuhiro Ogura , Haruo Kamijo , Shigeyasu Motohashi & Manabu Seno
2003) A Novel Synthesis of Cyclic Polythioethers Using Liquid-Liquid Phase-Transfer Catalysis, Phosphorus, Sulfur, and Silicon
(
and the Related Elements, 178:6, 1295-1301, DOI: 10.1080/10426500307887
To link to this article: http://dx.doi.org/10.1080/10426500307887
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

Phosphorus, Sulfur, and Silicon, 178:1295–1301, 2003
Copyright �C Taylor & Francis Inc.
ISSN: 1042-6507 print
DOI: 10.1080/10426500390200594
A NOVEL SYNTHESIS OF CYCLIC
POLYTHIOETHERS USING LIQUID-LIQUID
PHASE-TRANSFER CATALYSIS
Toshio Takido, Masaharu Toriyama, Kazuhiro Ogura,
Haruo Kamijo, Shigeyasu Motohashi, and Manabu Seno
Nihon University, Chiba, Japan
The synthesis of cyclic polythioethers has been achieved by the reactions
of dithiols with alkyl dihalides. Thiols are not only hard to handle
owing to their unpleasant smell, but also they are easily oxidizable, thus
it is not easy to obtain various dithiols. However, we have developed a
procedure for the preparation cyclic polythioethers by the reaction of
dithioiminium salts with alkyl dihalides using phase-transfer catalyst
without the use of dithiols, and have examined the ion recognition of
these compounds.
Keywords: Cyclic polythioether; phase-transfer catalysis; thioaceta-
mide; thiocrown; thioiminium salt
Many different methods for preparing cyclic polythioethers have been
reported,1
–22
and they are known to favor their complexing abil-
4
–9,23–29
ity with soft Lewis acids
because the sulfur atoms in the
thioether groups are acting as soft Lewis bases. In addition, they
have been shown to be effective ligands for low-valent transition metal
ions,3
0–33
whereas crown ethers prefer to coordinate alkaline and alka-
3
4–38
line earth metal ions.
However, the coordination chemistry studies
of cyclic polythioethers have progressed slowly owing to their lack of
availability,22 and the low yields obtained by conventional methods for
3
0,31
their preparation.
We have previously reported
3
9,40
an efficient method of synthesizing
sulfides and thiol esters using 1-(alkylthio) or 1-(acylthio)ethaniminium
halides as a source of alkanethiolate or thiocarboxylate ions. In an
This work was partly supported by the High-Tech Research Center at Nihon Univer-
sity, and a Grant from the Ministry of Education, Culture, Sports, Science, and Technology
to promote multi-disciplinary research projects.
Address correspondence to Toshio Takido, Department of Materials and Applied
Chemistry, College of Science and Technology, Nihon University, Kanda Surugadai,
Chiyoda-Ku, Tokyo 101-8308, Japan. E-mail: takido@chem.cst.nihon-u.ac.jp
1
295

1
296
T. Takido et al.
extension of this work, this article describes a novel and efficient method
0
for the synthesis of cyclic polythioethers using the reaction of 1,1 -
(
dithioalkane)diethaniminium salts which are utilized to generate a
variety of otherwise unavailable dithiolate ions. These react with alkyl
dihalides under phase-transfer conditions.
RESULTS AND DISCUSSION
The reaction of alkyl dihalide (2) with two-fold excess of thioacetamide
0
(
1) afforded 1,1 -(dithio-alkane)diethaniminium salt (3) in refluxing
�
chloroform for 2–3 h or at 70–80 C for 2 h without any solvent. The
yields of 3 range between 70–90%.
SCHEME 1
Alkyl dihalide (4) is added dropwise to a vigorously stirred reaction
0
mixture containing 1,1 -(dithioalkane)diethaniminium salt (3) in a two-
phase system consisting of benzene and an aqueous solution of sodium
�
hydroxide at 60–65 C for 6 h in the presence of tetrabutylammmonium
bromide (TBAB) as a phase-transfer catalyst. After the reaction is over,
the organic phase is analyzed by gel permeation chromatography (GPC)
using chloroform as an eluent. The main products of this reaction were
cyclic polythioethers (5) and linear polymers having sulfur atoms. Two
types of cyclic polythioethers (5) were obtained; 1:1 ratio (n = 1) and
the 2:2 ratio (n = 2) which were separated by column chromatography
on silica gel using hexane/EtOAc (9:1) as an eluent. The reaction did
not proceed in the absence of a phase-transfer catalyst under otherwise
identical conditions. The yields and physical properties of the cyclic
polythioethers are summarized in Table I.
The yields for the cyclic polythioethers depend on the kind of alkali
cations in the aqueous phase. While, the reaction time and the alkali
concentration of the aqueous solution exhibit only a slight dependence
1
2
on the yield. The reaction of 3 (R = (CH2)4) with 4 (R = (CH2)4) in a
benzene/30% aqueous sodium hydroxide system produces 1:1 stoichio-
metrical product 5g, dithio-10-crown-2, and 2:2 stoichiometrical prod-
uct 5h, tetrathio-20-crown-4, in 8 and 14% yield respectively. The use

1297

1
298
T. Takido et al.
of cesium hydroxide in place of sodium hydroxide increases the yield
of 2:2 stoichiometrical product 5h (17%), together with a decrease of
the 1:1 stoichiometrical product 5g (2%), and a small amount of 3:3
stoichiometrical product 5i (5%), hexathia-30-crown-6, as a new prod-
1
2
uct. Similarly, the reaction of 3 (R = (CH2)3) with 4 (R = (CH2)3)
in a benzene/sodium or potassium hydroxide system produces the 1:1
stoichiometrical compound 5c as the main product but the similar re-
action in a benzene/rubidium or cesium hydroxide system affords the
2
:2 stoichiometrical compound 5d as the main product.
These results show that the unit number (n) of cyclic polythioether
increases with an increase in the ionic radius of alkali cation. The alkali
cation plays an important role as a template in the formation of cyclic
polythioethers (5). The extractability of alkali, transition and heavy
36
metal ions by the cyclic polythioethers was evaluated, and typical
results are summarized in Table II.
All of the 2:2 stoichiometric products show a high selectivity toward
+
Ag , but the 1:1 stoichiometric product shows only about half the ex-
tractability of 2:2 product. Cyclic polythioethers 5b, 5d, 5f, and 5h have
+
2
0 to 50% extractability for ions other than Ag and 5k to 5u show only
+
a weak extractability except for Ag ion.
As far as we know, this is the first example of the synthesis
0
of cyclic polythioethers in sulfur chemistry using 1,1 -(dithioalkane)
diethaniminium salts. This method does not use malodorous
TABLE II Extraction of Alkaline, Transition Metal and Heavy
Metal Ions
Extraction (%)a
+
+
+
2+
2+
2+
+
2+
2+
Pb
Host
Li
Na
K
Co
Ni
Cu
Ag
Cd
5
5
5
5
5
5
5
5
5
5
5
5
g
l
b
d
f
h
k
m
o
q
s
4.2
2.0
1.7
2.6
5.6
3.8
2.9
4.1
1.8
1.3
8.9
2.0
6.0
7.2
1.4
5.2
2.9
20
2.6
2.2
7.6
6.2
6.6
0.9
2.9
20
6.8
50
5.0
3.0
7.4
3.6
9.0
5.4
2.6
2.8
3.8
8.4
5.8
5.4
44
66
99
99
98
99
99
92
98
91
97
96
5.0
3.6
28
6.0
7.0
2.0
11
9.2
4.8
12
5.0
3.0
4.8
2.4
22
5.0
9.0
3.0
6.0
6.0
6.1
23
4.5
8.3
8.4
2.5
3.9
3.4
4.9
3.8
1.9
6.8
1.3
2.2
3.9
1.1
2.2
4.1
1.5
17
36
3.0
5.8
3.0
4.8
6.2
2.8
8.4
6.4
4.4
11
4.4
6.6
13
5.2
5.2
u
None
0.6
0.7
1.5
1.5
1.1
1.4
1.8
0.6
1.8
a
� 4
Org. phase: (CH2ClCH2Cl); [Host] = 3.0 � 10 M; Aq. phase:
�
+
� 5
[
Pic H ] = 3.0 � 10 M, [Metal Nitrate] = 0.01 M.

Novel Synthesis of Cyclic Polythioethers
1299
compounds such as dithiols and can be applied widely to the synthesis of
various cyclic polythioethers under mild conditions. The selectivity and
yield of the reactions are relatively low, similar to previous methods,3
but our method will be more advantageous than conventional methods
for the preparation of cyclic polythioethers. Synthetic applications in-
cluding the optimum reaction conditions now are being investigated in
our laboratory.
0,31
EXPERIMENTAL
All reagents were commercially available chemicals. Melting points
were determined on a Yanako Micro melting point apparatus and are
uncorrected. IR spectra were recorded on a JASCO FT/IR-300E spec-
trophotometer. Mass spectra were recorded on a HITACHI M-80B spec-
trometer. (EI) or a JEOL GCmate (FAB). NMR spectra were recorded
on a JEOL GX-400.
0
1
1
,1 -(Dithiobutane)diethaniminium Salt 3 (R = (CH ) ):
2 4
Typical Procedure
A mixture of thioacetamide, 1, (15.03 g, 0.20 mmol) and 1,4-
1
dibromobutane, 2 (R = (CH2)4), (21.59 g, 0.10 mmol) in chloroform
is refluxed for 2 h. After cooling, the precipitate is collected by filtration
1
and washed with ether to give 3 (R = (CH2)4) (34.31 g, 94%) as a col-
�
� 1
+
orless solid of m.p. 196–198 C. IR (KBr) cm : 2850, 1620, 1269, 866,
6
2
94. HR-MS (FAB+) m/z: 285.0099 [(M-Br) ] (Calcd for C8H18N2S2Br:
85.0094).
Cyclic Polythioethers 11: General Procedure
0
A mixture of the freshly prepared 1,1 -(dithioalkane) diethaniminium
salt, 3, (20 mmol), tetrabutyl-ammmonium bromide (TBAB; 0.64 g,
2
.0 mmol) as phase-transfer catalyst, benzene (50 mL), and 30 wt%
�
aqueous sodium hydroxide (100 g) is vigorously stirred at 60–65 C for
1
h under nitrogen atmosphere. The alkyl dibromide, 4, (20 mmol) in
benzene (50 mL) is then added dropwise to the solution over 4 h. The re-
sulting solution is stirred further for 1 h. After the reaction, the organic
layer is separated, and the aqueous layer is extracted with benzene. The
combined organic layer is washed with water (3 � 100 mL), dried, and
evaporated. The cyclic polythioethers include the 1:1 and 2:2 stoichio-
metric products (5) which are isolated from residual product by column
chromatography on silica gel using hexane/EtOAc (9:1) as an eluent.

1
300
T. Takido et al.
Solvent Extraction of Metal Ions36
An aqueous solution (3 mL) containing 1 � 10 M metal nitrate and
�
2
�
5
3
� 10 M picric acid was placed in a 10 mL glass cylindrical tube
equipped with a glass stopper. After the addition of 3 mL of the 3 �
�
4
1
0
M cyclic polythioether (host) solution of 1,2-dichloroethane, the
�
mixture was vigorously shaken for 30 min at 25 C. The concentration
of the metal ion in the aqueous phase was determined by means of
ultraviolet spectrophotometry.
REFERENCES
[
[
1] R. S. Cooper (Ed.), Crown Compounds: Toward Future Applications (VCH Publish-
ers, New York, 1992); chap. 14.
2] L. F. Lindoy and D. H. Busch, Preparative Inorganic Reactions, edited by W. L. Jolly
(John Wiley & Sons, XX, 1971), vol. VI.
[3] J. S. Bradshaw and J. Y. K. Hui, J. Heterocycl. Chem., 11, 649 (1974).
[4] W. Rosen and D. H. Busch, Chem. Commun., 148 (1969).
[5] W. Rosen and D. H. Busch, J. Am. Chem. Soc., 91, 4694 (1969).
[6] D. St. C. Black and A. McLean, Tetrahedron Lett., 3961 (1969).
[7] W. Rosen and D. H. Busch, Inorg. Chem., 9, 262 (1970).
[8] K. Travis and D. H. Busch, Chem. Commun., 1041 (1970).
[9] K. Travis and D. H. Busch, Inorg. Chem., 13, 2591 (1974).
[10] L. A. Ochrymowycz, C. P. Mak, and J. D. Michna, J. Org. Chem., 39, 2079 (1974).
[11] T. E. Johnes, L. L. Zimmer, L. L. Diaddario, et al., J. Am. Chem. Soc., 97, 7163 (1975).
[12] E. R. Dockal, T. E. Johnes, N. F. Sokol, et al., J. Am. Chem. Soc., 98, 4322 (1976).
[13] T. Tabushi, H. Sasaki, and Y. Kuroda, J. Am. Chem. Soc., 98, 5727 (1976).
[14] D. Greber, P. Chongsawangvirod, K. Leung, and L. A. Ochrymowycz, J. Org. Chem.,
4
2, 2644 (1977).
[
[
[
[
[
15] P. Singh and A. Jain, Indian J. Chem., 26B, 707 (1987).
16] P. Singh, M. Kumar, and H. Singh, Indian J. Chem., 26B, 861 (1987).
17] R. D. Adams and S. B. Falloon, Chem. Rev., 95, 2587 (1995).
18] R. D. Adams, Acc. Chem. Res., 33, 171 (2000).
19] R. D. Adams, J. L. Perrin, J. A. Queisser, and R. D. Rogers, J. Organomet. Chem.,
5
96, 115 (2000).
[20] R. D. Adams, K. M. Brosius, and O.-S. Kwon, Inorg. Chem. Commun., 4, 671 (2001).
[21] T. Tsuchiya, T. Shimizu, and N. Kamigata, J. Am. Chem. Soc., 123, 11534 (2001).
[22] R. D. Adams, K. M. Brosius, and O.-S. Kwon, J. Organomet. Chem., 652, 51 (2002).
[23] S. Ahrland, J. Chatt, and N. R. Davies, Quart. Rev., London, 12, 265 (1958).
[24] D. W. Allen, P. N. Braunton, I. T. Millar, and J. C. Tebby, J. Chem. Soc., 3454 (1971).
[25] G. N. Schrauzer, R. K. Y. Ho, and B. P. Murillo, J. Am. Chem. Soc., 92, 3508 (1970).
[26] T. E. Johnes, D. B. Rorabacher, and L. A. Ochrymowycz, J. Am. Chem. Soc., 97, 7485
(1975).
[
[
[
[
[
27] N. W. Alcock, N. Herron, and P. Moore, Chem. Commun., 886 (1976).
28] R. E. DeSimon and M. D. Glick, J. Am. Chem. Soc., 97, 942 (1975).
29] R. E. DeSimon and M. D. Glick, J. Am. Chem. Soc., 98, 762 (1976).
30] R. S. Cooper, Acc. Chem. Res., 21, 141 (1988).
31] R. S. Cooper and S. C. Rawle, Struct. Bond., 72, 1 (1990).

Novel Synthesis of Cyclic Polythioethers
1301
[
[
32] A. J. Blake and M. Schroder, Adv. Inorg. Chem., 35, 1 (1990).
33] R. S. Cooper (Ed.), Crown Compounds: Toward Future Applications (VCH Publish-
ers, New York, 1992), chap. 15.
[
[
[
[
34] C. J. Pedersen, J. Am. Chem. Soc., 89, 2495 and 7017 (1967).
35] H. K. Frensdorff, J. Am. Chem. Soc., 93, 600 (1971).
36] N. S. Poonia, J. Am. Chem. Soc., 96, 1012 (1974).
37] R. M. Izatt, J. S. Bradshaw, S. A. Nielsen, J. D. Lamb, and J. J. Christensen, Chem.
Rev., 85, 271 (1985).
[
[
[
38] R. M. Izatt, K. Pawlak, and J. S. Bradshaw, Chem. Rev., 91, 1721 (1991).
39] T. Takido and K. Itabashi, Synthesis, 817 (1987).
40] T. Takido, M. Toriyama, and K. Itabashi, Synthesis, 404 (1988).