Scope and Limitations of a New Highly Selective Synthesis of Unsymmetrical Monomers for the Synthesis of Precursors toward Poly(arylenevinylene)s

Article abstract of DOI:10.1021/jo990111k

In our laboratory a precursor route to poly(p-phenylenevinylene) derivatives is developed in which unsymmetrically substituted p-xylene derivatives, possessing a benzylic sulfinylalkyl group, are used as monomers. Because of this unsymmetry, we were forced to investigate thoroughly the synthesis of these sulfoxides, as we start from symmetric and readily accessible molecules, namely, bis(halomethyl)-p-xylene derivatives. In a former publication, a new extremely effective route for the production of these unsymmetrically substituted sulfinyl monomers was presented. This paper expands upon these previously reported results. To examine the scope and limitations of this elegant route, this new method was applied to the synthesis of various derivatives not included in the initial work.

Full text of DOI:10.1021/jo990111k

284
J . Org. Chem. 2000, 65, 284-289
Scop e a n d Lim ita tion s of a New High ly Selective Syn th esis of
Un sym m etr ica l Mon om er s for th e Syn th esis of P r ecu r sor s tow a r d
P oly(a r ylen evin ylen e)s
Michael Van Der Borght, Dirk Vanderzande,* Peter Adriaensens, and J an Gelan
Laboratory for Organic and Polymer Chemistry, Division Chemistry, Institute for Material Research,
Limburg University, University Campus, B-3590 Diepenbeek, Belgium
Received J anuary 21, 1999
In our laboratory a precursor route to poly(p-phenylenevinylene) derivatives is developed in which
unsymmetrically substituted p-xylene derivatives, possessing a benzylic sulfinylalkyl group, are
used as monomers. Because of this unsymmetry, we were forced to investigate thoroughly the
synthesis of these sulfoxides, as we start from symmetric and readily accessible molecules, namely,
bis(halomethyl)-p-xylene derivatives. In a former publication, a new extremely effective route for
the production of these unsymmetrically substituted sulfinyl monomers was presented. This paper
expands upon these previously reported results. To examine the scope and limitations of this elegant
route, this new method was applied to the synthesis of various derivatives not included in the
initial work.
In tr od u ction
routes, of which one is very convenient, namely, the
nucleophilic substitution of a thiolate anion on a benzylic
halide (Route I, Scheme 1).16 A disadvantage bound to
this method is the difficulty to synthesize unsymmetric
sulfides starting from symmetrical p-xylene products
which have two identical benzylic halogenides. Indeed,
in this case a second substitution reaction only can be
avoided by the use of a 5-10-fold excess of the substrate.
The amount of substrate can be diminished significantly
to 2 or 3 equiv of bishalogenide by working with a phase-
transfer-catalyzed nucleophilic substitution. This method
also avoids the use of NaH and the necessity of water-
free conditions coupled therewith (Route II, Scheme
1).17,18
To avoid the drawbacks connected to the precursor
routes known from literature for the synthesis of poly-
(arylenevinylene) derivatives,1-12 a new precursor route
was developed in our laboratory. The monomers in this
route possess a benzylic leaving group and a benzylic so-
called polarizer which differs from the former. It was
shown that the use of an alkylsulfinyl group as the
polarizer and a halogen as the leaving group leads to
stable and soluble precursor polymers.13-15 These un-
symmetric sulfoxides are readily accessible via the oxida-
tion of the corresponding thioethers, meaning that the
first step to come to these sulfoxides is the synthesis of
the thioethers. These thioethers can be made via several
Despite this improvement, the synthesis of unsymmet-
ric monomers remains a delicate point in our route. An
excess of the substrate is necessary and bisthioalkylation,
in some measure, inevitable. As a consequence column
chromatography is a necessity in the purification process.
So, an alternative synthesis appeared to be desirable, and
a new highly selective route for the synthesis of these
unsymmetrically substituted monomers was developed
and recently published (Route III, Scheme 2).19 This
paper expands upon these previously reported results.
To elaborate the scope and limitations of this route, we
applied this new method to the synthesis of various
derivatives not included in the initial work. Like depicted
in Scheme 2, five steps can be distinguished in this new
route. The thiolate anion (1 equiv) withdraws a benzylic
proton from the bissulfonium salt 3a (1 equiv). Then the
p-quinodimethane system is formed by a 1,6-elimination,
and the unsymmetric thioether formed when a thiol
molecule attacks the p-quinodimethane system. Next,
octane is added to remove the THT by means of an
azeotropic distillation, in this way accelerating the
* To whom correspondence should be addressed. Tel.: +32 11
268321. Fax: +32 11 268301. E-mail: dvanderz@luc.ac.be.
(1) Kaul, S. N.; Fernandez, J . E. Macromolecules 1990, 23, 2875.
(2) Conticello, V. P.; Gin, D. L.; Grubbs, R. H. J . Am. Chem. Soc.
1992, 114, 9708.
(3) Pu, L.; Wagaman, M. W.; Grubbs, R. H. Macromolecules 1996,
29, 1138.
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(5) Iwatsuki, S.; Kubo, M.; Kumeuchi, T. Chem. Lett. 1991, 1071.
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67, 71.
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H.; Tak, H. Y.; Ba¨ssler, H.; Schmidt, C.; Lu¨ssem, G.; Schartel, B.;
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4, 1337.
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Div. Polym. Chem.) 1990, 31 (1), 505.
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1995, 269, 376.
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ecules 1995, 28, 1330.
(15) Vanderzande, D. J .; Issaris, A. C.; Van Der Borght, M. J .; van
Breemen, A. J .; de Kok, M. M.; Gelan, J . M. Polym. Prepr. (Am. Chem.
Soc., Div. Polym. Chem.) 1997, 38 (1), 321.
(16) Barrett, G. C. In Comprehensive Organic Chemistry, The
Synthesis and Reaction of Organic Compounds, Vol. 3, Organic
Sulphur Compounds; Neville J ones, D., Ed.; Pergamon Press: Oxford,
U.K., 1979.
(17) Herriott, A. W. Synthesis 1975, 447.
(18) Issaris, A.; Vanderzande, D.; Adriaensens, P.; Gelan, J . Mac-
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(19) van Breemen, A.; Vanderzande, D.; Adriaensens, P.; Gelan, J .
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10.1021/jo990111k CCC: $19.00 © 2000 American Chemical Society
Published on Web 12/29/1999

Synthesis of Precursors toward Poly(arylenevinylene)s
J . Org. Chem., Vol. 65, No. 2, 2000 285
Sch em e 1
As already mentioned, we tried to synthesize the
monosulfide of four different bissulfonium salts via this
procedure. The mixtures obtained are analyzed by means
of 1H NMR (which are given as Supporting Information)
or GC-MS (CI). The relative ratios of the bishalogenides,
the bissulfides, and the monosulfides are presented in
Table 1. We established that high relative amounts of
the monosulfide of the methyl (2h ), methoxy (2i), and
chloride (2j) substituted derivatives are formed. In the
last case, some water was added to the methanol because
of the low solubility of this salt 2j (with bromides as
counterions) in methanol. Clearly this has not influenced
the reaction. The amounts of bishalogenide and bissulfide
in theory should be the same, as approximately is in
accordance with the experimental results.
When the thiolate anion is added to the naphthylbis-
sulfonium salt 3e, dissolved in methanol, after 45 min
the conversion only comes to 42%. In other words, only
42% of the thiol is converted into the sulfide. Even after
24 h the conversion only amounts to 75%. In both of the
experiments no high relative amount of the monosulfide
is formed. According to a simple linear regression on
these results, at a conversion of 100%, the theoretical
distribution of 25 (bischloride):50 (monosulfide):25 (bis-
sulfide) is reached. Although we established that the
bissulfide precipitates from the reaction mixture, appar-
ently this phenomenon has no influence on the relative
distribution of the products formed during the reaction.
Thus, it is not possible to synthesize the monosulfide of
the naphthyl derivative 2d with a high relative yield via
this method. This is caused by the high resonance energy
of this derivative. As a matter of fact, this synthesis
proceeds via its p-quinodimethane system, and the
elimination reaction to form this p-quinodimethane
system is a high-energy step that involves the loss of
resonance energy of the aromatic system. Hence, a
driving force for the formation of the quinoid compound
is required, which in this case apparently is not large
enough. A consequence is that other derivatives possess-
ing high resonance energy, like the 4,4′-biphenyl deriva-
tive, cannot be used in this route. So, both the 2,6-
naphthyl and 4,4′-biphenyl sulfide derivatives 2d -f
described in this paper, are synthesized via a phase-
transfer-catalyzed nucleophilic substitution.
It can also be deduced from these two last experiments
that the nucleophilic substitution reaction, under these
conditions, is very slow. The other monosulfides were
synthesized under equivalent conditions, and these reac-
tions were already finished after 45 min. From this, it
can be concluded that the nucleophilic substitution is
hindered significantly, as it proceeds many times slower.
As a consequence, the relative amounts of bissulfide
found in the reaction mixtures 2g-j are very low.
Oxid a tion to th e Su lfoxid es. The oxidation of thio-
ethers can deliver both sulfoxides and sulfones.24 Soft
oxidation, which only delivers sulfoxides and avoids the
substitution of the sulfonium salt by the counterion, the
chloride anion.
UV-vis measurements confirmed this mechanism.
Indeed, it is possible to follow the progress of the reaction
because the benzoid (282 nm) and the quinoid (316 nm)
structures absorb at different wavelengths. In this man-
ner the formation and consumption of the quinoid
compound was established during the reaction.19
In this reaction bissulfonium salts are used for three
reasons. First, the pKa of a benzylic proton next to a
bissulfonium salt is low enough for a thiolate anion to
remove this proton. Second, a sulfonium salt is a good
leaving group, and third the halogenide is easily formed
by a nucleophilic attack of the counterion on the sulfo-
nium salt.
Former work has taught us that it is very important
to keep the number equivalents of the thiol, the base,
and the bissulfonium salt equal, to avoid a possible
bissubstitution or polymerization. Indeed, these bissul-
fonium salts are known as monomers for the so-called
Wessling polymerization, to synthesize precursor poly-
mers for conjugated polymers.8,9
Resu lts a n d Discu ssion
Syn th esis of th e Su lfid es. This new method is tested
on four different derivatives, which can be divided into
electron-rich derivatives, electron-poor derivatives, and
derivatives with an extended aromatic structure. First
the synthesis of the bissulfonium salts will be discussed
briefly, next the synthesis of the monosulfides, and finally
the oxidation to the sulfoxides, the monomers in our
precursor route (Scheme 3).
The first step in this strategy is the synthesis of the
bissulfonium salts. The procedures for the syntheses of
these salts are known from literature and are simple to
perform. Except for the synthesis of 3d , all of the
procedures are approximately the same.20-23 These bis-
sulfonium salts are very hygroscopic. Because the num-
ber of equivalents of the reagents used in the next step
is very critical, the amount of water bound to the salt
has to be known and is determined by 1H NMR measure-
ments.
(20) Burn, P. L.; Bradley, D. D. C.; Friend, R. H.; Halliday, D. A.;
Holmes, A. B.; J ackson, R. W.; Kraft, A. J . Chem. Soc., Perkin Trans.
1 1992, 3225.
(21) Beerden, A. Ph.D. Dissertation, Limburg University Centre,
Diepenbeek, Belgium, 1993.
(22) Antoun, S. Collect. Czech., Chem. Commun. 1987, 52, 162.
(23) McCoy, R. K.; Karasz, F. E.; Sarker, A.; Lahti, P. M. Chem.
Mater. 1991, 3 (5), 941.
(24) Durst, T. In Comprehensive Organic Chemistry: The synthesis
and reactions of Sulphur, Selenium, Silicon, Boron Organometallic
Compounds, Chapter 11.6 Sulphoxides; Neville J ones, D., Ed.; Perga-
mon: Oxford, U.K., 1979; p 121.

286 J . Org. Chem., Vol. 65, No. 2, 2000
Van Der Borght et al.
Sch em e 2
Sch em e 3
Ta ble 1. P r od u ct Distr ibu tion of Cr u d e Rea ction
Mixtu r es of Th ioeth er Syn th esis
Sch em e 4
MeOH/H2O bishalogenide bissulfide monosulfide
derivative
ratio
(%)
(%)
(%)
2g
2h
2i
2j
2d
1/0
1/0
1/0
4/1
1/0
5
8
9
7
60
5
6
11
7
90
86
80
86
38
2
overoxidation to sulfones, requires the appropriate reac-
tion conditions. H2O2, alone or together with several
solvents or catalysts, is a possible reagent for the oxida-
tion of organic sulfides to sulfoxides.25-27 A very simple
and efficient method is the tellurium-catalyzed oxidation
of the thioethers by means of H2O2 in methanol.28 If the
product, which must be oxidized, hardly dissolves in
methanol, a mixture of methanol and dioxane or even
pure dioxane is used. Because the rate of the oxidation
is rather low in dioxane, a drop of concentrated HCl is
added to the mixture, to accelerate the reaction (Scheme
4).
The sulfides are used impure, or only partially purified,
in this reaction. The reaction is followed with TLC and
terminated most of the times after 6-8 h. The sulfoxides
are purified with column chromatography, although it
must be possible to purify these sulfoxides without
column chromatography, owing to the low amount of side
products present in the crude reaction mixture. The
yields of the synthesis of the sulfoxides, starting from
the bishalogenide or the bissulfonium salt, are shown in
Table 2. Because we started with 2-3 equiv of bishalo-
genide in the phase-transfer-catalyzed reaction, the yields
will be rather low in these cases.
As already explained, it is possible to obtain high
relative yields of the monosulfide starting from bissul-
fonium derivatives, substituted with electron-donating
groups or inductive electron-withdrawing groups. The
oxidation of the sulfide to the sulfoxide is a reaction with
(25) Drabowicz, J .; Mikokajczyk, M. Synth. Commun. 1981, 11 (12),
1025.
(26) Fringuelli, F.; Pellegrino, R.; Pizzo, F. Synth. Commun. 1993,
23 (22), 3157.
(27) Bonadies, F.; De Angelis, F.; Locati, L.; Scettri, A. Tetrahedron
Lett. 1996, 37 (39), 7129.
(28) Kim, K. S.; Hwang, H. J .; Cheong, C. S.; Hahn, C. S. Tetrahe-
dron Lett. 1990, 31 (20), 2893.

Synthesis of Precursors toward Poly(arylenevinylene)s
J . Org. Chem., Vol. 65, No. 2, 2000 287
erwise noted. The bischlorides 1c,21 1f,30 1d ,31,32 and 1e31,32
were prepared as reported in the literature. Chromatographic
separations were performed on Macherey-Nagel silica gel
(particle size: 0.023-0.2 mm). TLC was performed on Merck
Ta ble 2. Over a ll Yield s of th e Su lfoxid es Syn th esized
via Rou te II or Rou te IIIa
yield route II (%)
yield route III (%)
silica gel 60F254
.
4a
4c
4e
-
38
28
3
4b
4d
4f
4g
4h
-
75
(Ch lor om eth yl)-4-[(bu tylsu lfa n yl)m eth yl]ben zen e (2a ).
A mixture of 99.7 g (0.569 mol) of 1a in 1000 mL of toluene,
60 g (1.5 mol) of NaOH in 1000 mL of H2O, and 2.5 g of a
phase-transfer catalyst, trioctylmethylammonium chloride
(Aliquat 336), is vigorously stirred at room temperature. A
solution of 30.5 mL (0.285 mol ) 0.5 equiv) of butanethiol in
300 mL of toluene is added drop by drop to this mixture. When
the thiol is added completely, the mixture is still stirred for 1
h more. The organic layer is separated, washed with water,
and dried over MgSO4. After the evaporation of the solvent, a
white-yellow crystalline product is obtained. This mixture
containing 1a , 2a , and 1,4-bis[(butylsulfanyl)methyl]benzene
is dried under vacuum. Next it is purified partially by a
recrystallization from hexane during which the bishalogenide
precipitates as white crystals. These crystals are filtered of
and washed with cold hexane. The mother liquor is reduced
on a rotary evaporator and the oil obtained oxidized to the
sulfoxide in the next step.
61
12
70
0
-
-
-
4h
4i
19
25
20
4j
-
a
- ) not carried out.
high yields. All of this is confirmed by the total yields of
the methyl- and chloride-substituted monomers 4d and
4g. However, the methoxy-substituted derivative 4f does
not confirm the expectations. According to our observa-
tions, this low yield is caused by an undesirable reaction
during the purification by column chromatography, be-
cause the crude mixture placed on the column mainly
1
consisted of monosulfoxide (80%) according to H NMR
measurements.
The following syntheses are performed in the same manner,
unless otherwise stated.
In the meantime, it appeared that the few percentages
of the side products present in the crude mixture do not
interfere with the polymerization of the sulfoxides.29 This
means that is not necessary anymore to purify the
sulfoxides, made via this new route, for this purpose.
After the polymerization the polymer is easily purified
by means of a simple precipitation in the appropriate
solvent, such that the polymer precipitates and the
monomers and side products stay in solution.
(Ch lor om eth yl)-4-[(bu tylsu lfa n yl)m eth yl]-2,5-d im eth -
ylben zen e (2b). A mixture of 30 g (0.148 mol) of 1b in 450
mL of toluene, 14.88 g (0.372 mol) of NaOH in 372 mL of water,
and 0.74 g (1.84 mmol) of Aliquat 336 is stirred vigorously.
To this is added over 24 h a solution of 7.9 mL (0.074 mol) of
butanethiol in 96.5 mL of toluene.
(Ch lor om eth yl)-4-[(bu tylsu lfa n yl)m eth yl]-2,5-d im eth -
oxyben zen e (2c). A total of 60 g (0.255 mol) of 3a is dissolved
in 1875 mL of toluene and stirred together with 17.25 g (0.43
mol) of NaOH in 500 mL of water and 0.86 g (2.14 mmol) of
Aliquat 336. To this is added over 24 h 9.12 mL (0.085 mol) of
butanethiol in 120 mL of toluene. The excess 1c is recuperated
partially by a recrystallization from a mixture of hexane and
CHCl3 (ratio: 2/1).
2-(Ch lor om et h yl-6-[(oct ylsu lfa n yl)m et h yl]n a p h t h a -
len e (2d ). A total of 23 g (0.1 mol) of 1d is dissolved in 1100
mL toluene. To this is added 10.5 g (0.263 mol) of NaOH
dissolved in 230 mL, of H2O, together with 0.44 g of Aliquat
336. A total of 8.5 mL (0.05 mol) of octanethiol dissolved in 53
mL of toluene is added slowly over 24 h. Afterward the raw
mixture is recrystallized from a mixture of hexane and CHCl3,
during which the 1d partially precipitates as white crystals.
4-(Ch lor om et h yl)-4′-[(b u t ylsu lfa n yl)m et h yl]b ip h en yl
(2e) a n d 4-(Ch lor om eth yl)-4′-[(octylsu lfa n yl)m eth yl]bi-
p h en yl (2f). These compounds were synthesized according to
the procedure described for the synthesis of 2a .
Deter m in a tion of th e Am ou n t Wa ter bou n d to Th e
Su lfon iu m sa lts. First the amount of H2O in D2O used for
the 1H NMR measurement is determined. Next, the sample
of the bissulfonium salt, dissolved in D2O, is measured under
equivalent conditions. The amount of H2O in the D2O sample
is subtracted from the total amount of water in the salt sample,
and the intensity of the water signal is compared with the
intensity of a signal of the salt itself (for instance, an aromatic
proton). From this, the amount of water bound to the salt is
deduced. For the synthesis of the sulfide we work with the
adapted molecular weight, including the water bound to the
molecule.
Con clu sion s
Bissulfonium salts can be used as starting materials
for the synthesis of unsymmetric benzylic sulfides. Namely,
it is possible to obtain high yields (90%) of the monosul-
fide starting from a symmetric bissulfonium salt, 1 mol
equiv of Na+tBuO- and 1 mol equiv of a thiol, via the
effective procedure described. Until now it is proven that
it is possible to synthesize unsymmetric benzylic sulfides
from bissulfonium derivatives substituted with electron-
donating groups or inductive electron-withdrawing groups
via this new and efficient route. These sulfides are easily
oxidized to their corresponding sulfoxides, which are the
monomers for the synthesis of poly(arylenevinylene)
precursors, with H2O2 an TeO2 in methanol and/or
dioxane.
Exp er im en ta l Section
Gen er a l Meth od s. Melting points are uncorrected. Mass
spectra were determined at an ionizing voltage of 70 eV. The
reagent gas was i-butane, and the reagent gas pressure was
3000-4000 mTorr if chemical ionization was used. For the
infrared spectroscopy measurements, KBr pellets were used.
13C NMR spectra were recorded at 100 MHz and 1H NMR
spectra at 200, 300, or 400 MHz. The chemical shift assign-
ment was based on 1D APT, 2D COSY, and HETCOR
(optimized for direct and vicinal coupling) experiments, and
values are given in ppm relative to internal TMS as the
standard.
1,4-Bis[(t et r a h yd r ot h iop h en io ch lor id e)m et h yl]-2,5-
d im eth ylben zen e (3b). Synthesis is according to ref 20: mp
146.0-147.5 °C (lit. mp 147.0-149.0 °C); FT IR (KBr, ν, cm-1
)
Ma ter ia ls. All solvents and reagents were purchased from
ACROS or Aldrich except NaOH, MgSO4 (VEL), 1b (Lan-
caster), and octane (Fluka). All of these materials are reagent
grade and are used without further purification unless oth-
(30) McCoy, R. K.; Karasz, F. E.; Sarker, A.; Lahti, P. M. Chem.
Mater. 1991, 3 (5), 941.
(31) Furniss, B. S.; Hannaford, A. J .; Smith, P. W. G.; Tatchell, A.
R. Vogel’s Textbook of Practical Organic Chemistry, 5th ed.; Longman
Scientific & Technical: Harlow, U.K., 1989; p 530.
(32) Furniss, B. S.; Hannaford, A. J .; Smith, P. W. G.; Tatchell, A.
R. Vogel’s Textbook of Practical Organic Chemistry, 5th ed.; Longman
Scientific & Technical: Harlow, U.K., 1989; 555.
(29) Lutsen, L.; van Breemen, A.; Vanderzande, D.; Gelan, J .
Tetrahedron 1999, submitted.

288 J . Org. Chem., Vol. 65, No. 2, 2000
Van Der Borght et al.
2976, 2931, 1613, 1461, 1259; 1H NMR (δ, D2O, 400 MHz) 7.23
(s, 2H), 4.38 (s, 4H), 3.32 (m, 8H), 2.25 (m, 8H).
CHCl3. The combined organic layers are dried over MgSO4 and
reduced on a rotary evaporator. The mixture, existing of 1a ,
some 1,4-bis[(butylsulfinyl)methyl]benzene, and 4a , is sepa-
rated by means of column chromatography (silica, CHCl3),
after which 4a is recrystallized from toluene and dried under
vacuum (yield calculated from 38% 1a ): mp 111.0-112.0 °C;
IR (KBr, ν, cm-1) 3060, 2970-2870, 1450-1410, 1010, 850,
1,4-Bis[(t et r a h yd r ot h iop h en io ch lor id e)m et h yl]-2,5-
d im eth oxyben zen e (3c). Synthesis is according to ref 21: mp
176.5-178.9 °C; FT IR (KBr, ν, cm-1) 2976, 2950, 2885, 1513,
1461, 1398, 1233, 1031, 690; 1H NMR (δ, D2O, 400 MHz) 7.10
(s, 2H), 4.43 (s, 4H), 3.81 (s, 6H), 3.40 (m, 8H), 2.21 (m, 8H).
1,4-Bis[(t et r a h yd r ot h iop h en io b r om id e)m et h yl]-2,5-
d ich lor oben zen e (3d ). Synthesis is according to ref 23: mp
3
730, 660; 1H NMR (δ, CDCl3, 400 MHz) 7.38 (d, J ) 8.18 Hz,
2H), 7.27 (d, 3J ) 8.18 Hz, 2H), 4.55 (s, 2H), 3.96 (d, 2J ) 13.20
Hz, 1H), 3.92 (d, 2J ) 13.20 Hz, 1H), 2.56 (t, 3J ) 7.96 Hz,
161.6-163.8 °C (lit. mp 160.0-161.0 °C); FT IR (KBr, ν, cm-1
)
2994, 2927, 2888, 2822, 1479, 1411, 1371, 1260, 1083, 907; 1H
NMR (δ, D2O, 200 MHz) 7.74 (s, 2H), 4.56 (s, 4H), 3.45 (m,
8H), 2.30 (m, 8H).
2H), 1.70 (m, 2H), 1.41 (m, 2H), 0.90 (t, 3J ) 7.34 Hz, 3H); 13
C
NMR (δ, CDCl3) 136.8, 129.9, 129.8, 128.4, 56.9, 50.2, 45.1,
23.8, 21.3, 13.1; MS (EI, m/z, relative intensity in %) 244 (M+,
9), 209 (M+ - Cl, 5), 139 (M+ - S(O) - Bu, 100), 104 (M+ - Cl
- S(O) - Bu, 19), 77 (M+ - CH2Cl - CH2S(O) - Bu, 5).
The following syntheses are carried out in the same manner,
unless otherwise stated.
2,6-Bis[(tetr a h yd r oth iop h en io ch lor id e)m eth yl]n a p h -
th a len e (3e). Synthesis is according to ref 22: mp 146.5-
149.4 °C; FT IR (KBr, ν, cm-1) 2936, 1624, 1408, 1261, 897,
831; 1H NMR (δ, D2O, 300 MHz) 7.97 (s, 2H), 7.96 (d, 3J )
3
8.43 Hz, 2H), 7.56 (d, J ) 8.36 Hz, 2H), 4.60 (s, 4H), 3.41 (m,
(Ch lor om eth yl)-4-[(bu tylsu lfin yl)m eth yl]-2,5-d im eth -
ylben zen e (4c). A total of 1.17 g (7.33 mmol) of TeO2 is added
to a solution of the partially purified 2b in 300 mL of MeOH.
A total of 14.36 mL (0.127 mol) of a H2O2 solution is added.
After column chromatography (silica, CHCl3), 4c is recrystal-
lized from a mixture of hexane and CH2Cl2 (10/1), giving 10.9
g of white crystals (yield calculated from 1b 28%): mp 112.9-
114.0 °C; IR (KBr, ν, cm-1) 2980, 2930, 2900, 2840, 1440, 1240,
1020, 880, 660; 1H NMR (δ, CDCl3, 400 MHz) 7.15 (s, 1H),
8H), 2.22 (m, 8H).
(Ch lor om eth yl)-4-[(octylsu lfa n yl)m eth yl]-2,5-d im eth -
ylben zen e (2h ). A total of 2 g (5.27 mmol) of 3b is dissolved
in 27 mL of MeOH and stirred. A mixture of 0.48 g (5.03 mmol)
of Na+tBuO- and 0.7 g (4.76 mmol) of octanethiol, dissolved
in 15 mL of MeOH, is added at once, while the mixture is
stirred vigorously. After 45 min the mixture is neutralized by
the addition of 0.1 M HCl, and MeOH is evaporated. Further
octane is added to remove THT completely by azeotropic
distillation. The residue is dissolved in a sufficient quantity
of CHCl3 whereupon this solution is filtered to remove the
NaCl formed. The filtrate is reduced on a rotary evaporator
and used without further purification: 1H NMR (δ, CDCl3, 400
MHz) 7.09 (s, 1H), 7.01 (s, 1H), 4.55 (s, 2H), 3.64 (s, 2H), 2.45
2
7.03 (s, 1H), 4.53 (s, 2H), 4.02 (d, J ) 12.60 Hz, 1H), 3.90 (d,
2J ) 12.60 Hz, 1H), 2.64 (m, 2H), 2.35 (s, 3H), 2.34 (s, 3H),
1.74 (m, 2H), 1.44 (m, 2H), 0.92 (t, 3J ) 7.20 Hz, 3H); 13C NMR
(δ, CDCl3) 135.62, 135.12, 135.09, 133.21, 132.12, 129.47,
56.61, 51.39, 44.23, 24.47, 21.97, 19.17, 18.11, 13.63; MS (EI,
m/z, relative intensity in %) 237 (M+ - Cl, 1), 167 (M+ - S(O)
- Bu, 100), 132 (M+ - S(O) - Bu - Cl, 15).
3
(t, J ) 7.28 Hz, 2H), 2.35 (s, 3H), 2.33 (s, 3H), 1.56 (m, 2H),
3
1.34 (m, 2H), 1.25 (m, 8H), 0.87 (t, J ) 6.80 Hz, 3H).
(Ch lor om eth yl)-4-[(octylsu lfin yl)m eth yl]-2,5-d im eth yl-
ben zen e (4d ). A total of 0.08 g (0.48 mol) of TeO2 is added to
a solution of the partially purified 2h in a mixture of 22 mL
of MeOH and 7 mL of dioxane. A total of 0.8 mL (8.6 mmol) of
a H2O2 solution is added. After purification by means of column
chromatography, 4d is recrystallized from hexane, giving 4d
as white crystals (yield calculated from 61% 3b): mp 77.3-
78.8 °C; FT IR (KBr, ν, cm-1) 2959, 2922, 2851, 1508, 1459,
1020, 890, 663; 1H NMR (δ, CDCl3, 400 MHz) 7.14 (s, 1H),
The syntheses of the following thioethers are the same as
the synthesis of 2h unless otherwise stated.
(Ch lor om eth yl)-4-[(octylsu lfa n yl)m eth yl]-2,5-d im eth -
oxyben zen e (2i). A total of 8 g (0.0185 mol, inclusive bound
water) of 3c is dissolved in 130 mL of methanol and stirred. A
mixture of 1.81 g (0.019 mol) of Na+tBuO- and 2.76 g (0.019
mol) of octanethiol, dissolved in 60 mL of methanol, is added:
1H NMR (δ, CDCl3, 300 MHz) 6.86 (s, 1H), 6.85 (s, 1H), 4.62
(s, 2H), 3.82 (s, 3H), 3.80 (s, 3H), 3.70 (s, 2H), 2.45 (t, 3J )
7.35 Hz, 2H), 1.57 (m, 2H), 1.30 (m, 2H), 1.24 (m, 8H), 0.85 (t,
3J ) 6.86 Hz, 3H).
2
7.03 (s, 1H), 4.53 (s, 2H), 4.02 (d, J ) 12.40 Hz, 1H), 3.90 (d,
2J ) 12.40 Hz, 1H), 2.36 (m, 2H), 1.75 (m, 2H), 1.39 (m, 2H),
3
1.25 (m, 8H), 0.85 (t, J ) 7.23 Hz, 3H); 13C NMR (δ, CDCl3)
(Br om om et h yl)-4-[(oct ylsu lfa n yl)m et h yl]-2,5-d ich lo-
r oben zen e (2j). A total of 15.59 g (0.030 mol, inclusive bound
water) of 3d is dissolved in a mixture of 240 mL of MeOH and
67 mL of H2O and stirred. A mixture of 2.91 g (0.030 mol) of
Na+tBuO- and 4.34 g (0.029 mol) of octanethiol, dissolved in
a mixture of 81 mL of MeOH and 21 mL of H2O, is added: 1H
NMR (δ, CDCl3, 200 MHz) 7.43 (s, 1H), 7.40 (s, 1H), 4.49 (s,
2H), 3.73 (s, 2H), 2.45 (t, 3J ) 7.21 Hz, 2H), 1.54 (m, 2H), 1.24
(m, 10H), 0.85 (t, 3J ) 6.49 Hz, 3H); MS (EI, m/z, relative
intensity in %) 396 (M+, 1), 317 (M+ - Br, 1), 253 (M+ - S -
Oct, 6), 172 (M+ - S - Oct - Br, 29), 145 (S - Oct, 100), 137
(M+ - S - Oct - Br - Cl, 1), 102 (M+ - S - Oct - Br - 2Cl,
5).
2-(Ch lor om et h yl)-6-[(oct ylsu lfa n yl)m et h yl]n a p h t h a -
len e (2d ). A total of 2.28 g (4.98 mmol inclusive bound water)
of 3e is dissolved in 50 mL of MeOH and stirred. A mixture of
0.48 g (4.98 mmol) of Na+tBuO- and 0.73 g (4.98 mol) of
octanethiol, dissolved in 17 mL of MeOH, is added: MS (CI,
m/z, relative intensity in %) 335 (MH+, 100), 299 (M+ - Cl, 9),
189 (M+ - S - Oct, 10), 155 (M+ - S - Oct - Cl, 3).
(Ch lor om eth yl)-4-[(bu tylsu lfin yl)m eth yl]ben zen e (4a ).
A total of 4.61 g (0.029 mol) of TeO2 is added to a solution of
the partially purified 1c in 1200 mL of MeOH. A total of 65
mL (0.570 mol) of a H2O2 solution in H2O (35 wt %) is added
slowly to the stirred solution. The reaction mixture is stirred
at room temperature and the reaction followed with TLC
(silica, CHCl3). When, after 6-8 h, the reaction is finished or
a new spot as a consequence of oxidation to the sulfone
appears, the reaction is stopped by the addition of 800 mL of
brine. The aqueous layer is extracted several times with
136.26, 135.77, 135.72, 133.86, 132.76, 130.13, 56.63, 51.69,
44.27, 31.67, 29.13, 28.95, 28.78, 22.57, 22.52, 19.24, 18.17,
14.05; MS (EI, m/z, relative intensity in %) 293 (M+ - Cl, 6),
277 (M+ -Cl - O, 1), 132 (M+ - Cl - S(O) - Oct, 100), 117
(M+ - Cl - S(O) - Oct - CH3, 13).
(Ch lor om eth yl)-4-[(bu tylsu lfin yl)m eth yl]-2,5-d im eth -
oxyben zen e (4e). A total of 1.08 g (6.79 mmol) of TeO2 is
added to a solution of 16 g of the partially purified 2c in 640
mL of MeOH. A total of 13.3 mL (0.117 mol) of a H2O2 solution
is added. After purification by column chromatography, 4e is
recrystallized from a mixture of ether and hexane, giving 1.80
g of white crystals (yield calculated from 1c 3%): mp 75.4-
76.6 °C; IR (KBr, ν, cm-1) 2920, 2900, 2830, 1490, 1450, 1395,
1310, 1250, 1200, 1030, 1105, 855, 660; 1H NMR (δ, CDCl3,
2
400 MHz) 6.91 (s, 1H), 6.82 (s, 1H), 4.61 (s, 2H), 4.07 (d, J )
2
3
12.40 Hz, 1H), 3.90 (d, J ) 12.40 Hz, 1H), 3.82 (s, H), 3.80
3
3
(s, H), 2.60 (m, 2H), 1.73 (m, 2H), 1.44 (m, 2H), 0.91 (t, J )
7.25 Hz, 3H); 13C NMR (δ, CDCl3) 151.19, 150.93, 126.30,
119.71, 114.65, 112.87, 56.08, 76.68, 52.52, 51.01, 41.19, 24.38,
21.92, 13.57; MS (CI, m/z, relative intensity in %) 305 (M+,
100), 269 (M+ - Cl, 8), 199 (M+ - S(O) - Bu, 22), 165 (M+
S(O) - Bu - Cl, 4).
-
(Ch lor om et h yl)-4-[(oct ylsu lfin yl)m et h yl]-2,5-d im et h -
oxyben zen e (4f). A total of 0.30 g (0.89 mol) of TeO2 is added
to a solution of 6.5 g of the partially purified 2i in 50 mL of
dioxane. A total of 3.7 mL (0.038 mol) of a H2O2 solution is
added. After separation by column chromatography, 4f is
recrystallized from hexane, giving 0.81 g of white fluffy crystals
(yield calculated from 12% 3c): mp 88.6-90.4 °C; FT IR (KBr,
ν, cm-1) 2916, 2851, 1512, 1471, 1406, 1320, 1265, 1214, 1043,

Synthesis of Precursors toward Poly(arylenevinylene)s
J . Org. Chem., Vol. 65, No. 2, 2000 289
1021, 871, 678; 1H NMR (δ, CDCl3, 400 MHz) 6.92 (s, 1H),
of CHCl3 and hexane, giving 4i as white crystals (yield
calculated from 25% 1e): mp 175.5-176.1 °C; FT IR (KBr, ν,
cm-1) 2955, 2923, 2858, 1496, 1400, 1268, 1023, 831, 730, 671;
2
6.82 (s, 1H), 4.62 (s, 2H), 4.07 (d, J ) 12.40 Hz, 1H), 3.91 (d,
2J ) 12.40 Hz, 1H), 3.80 (s, 3H), 3.78 (s, 3H), 2.60 (t, 3J )
7.83 Hz, 2H), 1.73 (m, 2H), 1.39 (m, 2H), 1.25 (m, 8H), 0.85 (t,
3J ) 6.84 Hz, 3H); 13C NMR (δ, CDCl3) 151.31, 351.06, 126.45,
119.78, 114.81, 112.97, 56.26, 56.04, 52.69, 51.48, 31.69, 29.18,
28.99, 28.87, 22.56, 22.56, 14.05; MS (CI, m/z, relative intensity
in %) 361 (MH+, 100), 325 (M+ - Cl, 6), 199 (M+ - S(O) -
Oct, 20), 165 (M+ - S(O) - Oct - Cl, 7).
3
1H NMR (δ, CDCl3, 400 MHz) 7.57 (d, J ) 8.22 Hz, 2H), 7.56
3
3
3
(d, J ) 8.22 Hz, 2H), 7.45 (d, J ) 8.22 Hz, 2H), 7.35 (d, J )
2
2
8.22 Hz, 2H), 3.97 (d, J ) 13.00 Hz, 1H), 4.01 (d, J ) 13.00
Hz, 1H), 2.60 (t, 3J ) 7.57 Hz, 2H), 1.73 (m, 2H), 1.45 (m, 2H),
0.92 (t, 3J ) 7.30 Hz, 3H); 13C NMR (δ, CDCl3) 140.42, 140.35,
136.67, 130.45, 129.15, 129.06, 127.49, 127.30, 57.64, 50, 45.87,
24.38, 21.95, 13.61; MS (CI, m/z, relative intensity in %) 304
(M+ - O, 1), 285 (M+ - Cl, 1), 269 (M+ - O - Cl, 87), 215 (M+
(Br om om et h yl)-4-[(oct ylsu lfin yl)m et h yl]-2,5-d ich lo-
r oben zen e (4g). A total of 0.48 g (3.03 mmol) of TeO2 is added
to a solution of the partially purified 2j in 184 mL of dioxane.
A total of 6 mL (0.060 mol) of a H2O2 solution and 1 drop of a
concentrated HCl solution are added. After separation by
column chromatography, 4g is recrystallized from hexane,
giving 8.80 g of white crystals (yield calculated from 70% 3d ):
mp 60.6-61.2 °C; FT IR (KBr, ν, cm-1) 2955, 2919, 2844, 1476,
1370, 1084, 892, 872, 636; 1H NMR (δ, CDCl3, 200 MHz) 7.50
- S(O) - Bu, 94), 195 (M+ - phenyl - CH2Cl, 17), 180 (M+
-
Cl - S(O) - Bu, 100), 152 (M+ - CH2S(O) - Bu - CH2Cl, 8),
90 (M+ - phenyl - CH2S(O) - Bu, 4).
4-(Ch lor om eth yl)-4′-[(octylsu lfin yl)m eth yl]biph en yl (4j).
A total of 1.13 g (7.11 mmol) of TeO2 is added to a solution of
the partially purified 2f in a mixture of 40 mL of dioxane and
250 mL of MeOH. A total of 15.8 mL (0.138 mol) of a H2O2
solution is added. After separation by column chromatography,
4j is recrystallized from a mixture of CHCl3 and hexane, giving
4j as white crystals (yield calculated from 1e 20%): mp 161.5-
162.9 °C; FT IR (KBr, ν, cm-1) 2956, 2916, 2848, 1496, 1467,
1400, 1025, 830, 732, 673; 1H NMR (δ, CDCl3, 400 MHz) 7.57
2
(s, 1H), 7.43 (s, 1H), 4.49 (s, 2H), 4.13 (d, J ) 12.90 Hz, 1H),
3.94 (d, 2J ) 12.90 Hz, 1H), 2.69 (t, 3J ) 7.67 Hz, 2H), 1.77
(m, 2H), 1.40 (m, 2H), 1.25 (m, 8H), 0.85 (t, 3J ) 6.44 Hz, 3H);
13C NMR (δ, CDCl3) 136.47, 132.86, 132.54, 132.31, 131.41,
130.41, 54.63, 51.73, 31.26, 28.72, 28.55, 28.55, 28.36, 22.18,
22.18, 13.72; MS (EI, m/z, relative intensity in %) 414 (M+, 1),
333 (M+ - Br, 1), 253 (M+ -S(O) - Oct, 100), 172 (M+ - Br -
S(O) - Oct, 41), 137 (M+ - Br - Cl - S(O) - Oct, 6), 102 (M+
- Br - 2 Cl - S(O) - Oct, 9).
3
3
3
(d, J ) 8.22 Hz, 2H), 7.55 (d, J ) 8.22 Hz, 2H), 7.44 (d, J )
3
8.22 Hz, 2H), 7.35 (d, J ) 8.22 Hz, 2H), 4.61 (s, 2H), 3.97 (d,
2J ) 12.80 Hz, 1H), 4.02 (d, J ) 12.80 Hz, 1H), 2.61 (m, 2H),
2
1.74 (m, 2H), 1.39 (m, 2H), 1.25 (m, 8H), 0.84 (t, 3J ) 7.05 Hz,
3H); 13C NMR (δ, CDCl3) 140.37, 140.32, 136.64, 130.41,
129.14, 129.01, 127.45, 127.25, 57.63, 50.95, 45.84, 31.59,
29.03, 28.87, 28.71, 22.47, 22.39, 13.96; MS (EI, m/z, relative
2-(Ch lor om et h yl)-6-[(oct ylsu lfin yl)m et h yl]n a p h t h a -
len e (4h ). A total of 0.80 g (0.005 mol) of TeO2 is added to a
solution of the partially purified 2d in a mixture of 100 mL of
dioxane and 400 mL of MeOH. A total of 11.5 mL (0.101 mol)
of a H2O2 solution is added. After separation by column
chromatography, 4h is recrystallized from toluene, giving 4h
as white crystals (yield calculated from 19% 1d ): mp 133.2-
134.7 °C; FT IR (KBr, ν, cm-1) 2954, 2922, 2849, 1496, 1266,
intensity in %) 360 (M+ - O, 1), 341 (M+ - Cl, 1), 215 (M+
S(O) - Oct, 100), 180 (M+ - Cl - S(O) - Oct, 29), 152 (M+
CH2Cl - CH2S(O) - Oct, 3).
-
-
Ack n ow led gm en t. This research is performed as a
part of the program “Inter University Attraction Pole”
(IUAP; Contract No. P4/11) supported by the Belgian
government. The authors are grateful to the Flemish
Institute for Promotion of the Scientific-Technological
Research in the Industry (IWT), the Flemish Fund for
Scientific Research (FWO), and Hoechst A.G. for their
financial support. We also thank J . Czech for the mass
spectrometry measurements.
3
1027, 902, 834, 708; 1H NMR (δ, CDCl3, 400 MHz) 7.73 (d, J
) 8.56 Hz, 2H), 7.72 (s, 1H), 7.68 (s, 1H), 7.43 (d, 3J ) 8.48
3
2
Hz, 1H), 7.34 (d, J ) 8.44 Hz, 1H), 4.66 (s, 2H), 4.19 (d, J )
2
13.00 Hz, 1H), 4.10 (d, J ) 13.00 Hz, 1H), 2.53 (m, 2H), 1.68
(m, 2H), 1.31 (m, 2H), 1.18 (m, 8H), 0.81 (t, 3J ) 6.94 Hz, 3H);
13C NMR (δ, CDCl3) 135.12, 132.67, 132.36, 128.80, 128.46,
128.34, 128.11, 127.80, 127.05, 126.64, 58.06, 50.87, 46.14,
31.39, 28.84, 28.67, 28.49, 22.30, 22.20, 13.82; MS (EI, m/z,
relative intensity in %) 350 (M+, 1), 334 (M+ - O, 1), 315 (M+
- Cl, 1), 299 (M+ - O - Cl, 1), 189 (M+ - S(O) - Oct, 100),
154 (M+ - S(O) - Oct - Cl, 22).
Su p p or tin g In for m a tion Ava ila ble: 1H NMR spectra of
2h -j and 2d for the determination of the amounts of bischlo-
ride, monosulfide, and bissulfide. 1H and 13C NMR spectra for
new compounds 4a -j. This material is available free of charge
via the Internet at http:pubs.acs.org.
4-(Ch lor om et h yl)-4′-[(b u t ylsu lfin yl)m et h yl]b ip h en yl
(4i). A total of 0.49 g (0.003 mol) of TeO2 is added to a solution
of the partially purified 2e in 180 mL of MeOH. A total of 7
mL (0.062 mol) of a H2O2 solution is added. After separation
by column chromatography, 4i is recrystallized from a mixture
J O990111K