A novel and efficient method for the synthesis of polyfluoroarenesulfonyl bromides from polyfluoroarenethiols

Article abstract of DOI:10.1016/j.jfluchem.2009.09.011

The first general methodology has been developed for the synthesis of polyfluoroarenesulfonyl bromides from polyfluoroarenethiols. At heating of polyfluoroarenethiols with a mixture of Br₂ and fuming HNO₃ or Br₂, HNO₃ and H₂SO₄ polyfluoroarenesulfonyl bromides were obtained in good yields.

Full text of DOI:10.1016/j.jfluchem.2009.09.011

Journal of Fluorine Chemistry 131 (2010) 13–16
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
A novel and efficient method for the synthesis of polyfluoroarenesulfonyl
bromides from polyfluoroarenethiols
*
Vyacheslav E. Platonov , Roman A. Bredikhin, Alexander M. Maksimov, Victor V. Kireenkov
N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry Siberian Division of Russian Academy of Sciences, Lavrentiev Ave., 9, 630090 Novosibirsk, Russian Federation
A R T I C L E I N F O
A B S T R A C T
Article history:
The first general methodology has been developed for the synthesis of polyfluoroarenesulfonyl bromides
from polyfluoroarenethiols. At heating of polyfluoroarenethiols with a mixture of Br2 and fuming HNO3
or Br2, HNO3 and H2SO4 polyfluoroarenesulfonyl bromides were obtained in good yields.
ß 2009 Elsevier B.V. All rights reserved.
Received 3 July 2009
Received in revised form 16 September 2009
Accepted 19 September 2009
Available online 28 September 2009
Dedicated to Prof. Dr. H. C. Hermann-Josef
Frohn on the occasion of his 65th birthday.
Keywords:
Polyfluoroarenesulfonyl bromide
Polyfluoroarenethiol
Oxidation
Bromine
Nitric acid
1. Introduction
this connection polyfluoroarenesulfonyl bromides could be used
for introduction of polyfluoroarenesulfonyl group in olefins.
Among the chemical properties of polyfluoroaromatic com-
pounds, the reactions of polyfluoroarenes with electrophilic
reagents, which consist in interaction of the latter with a functional
group of polyfluoroarenes, are of interest. These reactions can
transform simple readily installed substituents in perfluoroaro-
matic ring to more complicated and otherwise inaccessible
functional group. Some examples of these reactions are considered
in [1,2]. In this connection it seemed reasonable to study the
transformation of polyfluoroarenethiols under the action of
electrophilic reagents into practically inaccessible sulfonyl bro-
mide derivatives of polyfluoroarenes.
Previously, pentafluorobenzenesulfonyl bromide (1) was
described as the only representative of polyfluoroaromatic
sulfonyl bromides. For the synthesis of compound 1, the reaction
of pentafluorophenylmagnesium chloride with sulfur dioxide and
bromine was performed; this also produces a significant quantity
of bis(pentafluorophenyl)sulfone. The chemistry of pentafluor-
obenzenesulfonyl bromide obtained was poor [3].
It has been shown that N-substituted polyfluorobenzenesulfo-
namides inhibited the growth of cancer cells in vitro [5].
Therefore, the relative reactivities of polyfluoroarenesulfonyl
chlorides and bromides with amines could be of interest for
polyfluoroarenesulfonamide synthesis. It is known that polyfluor-
oarenesulfonyl chlorides are used for preparation of the corre-
sponding sulfonamides [6].
In order to expand knowledge of the properties of polyfluor-
oarenesulfonyl halides it seems interesting to study the reactivities
of ArfSO2X (X = F, Cl, Br) to a more complete extent for a broader
understanding of the synthetic aspects of these compounds.
In the present paper, the results of investigation of the reactions
of polyfluoroarenethiols with Br2 and fuming HNO3 or other
bromine-containing oxidative systems are considered, the objec-
tive being to determine the possibility of forming polyfluoroar-
enesulfonyl bromides.
2. Results and discussion
Polyfluoroarenesulfonyl bromides could be of considerable
interest as sources of polyfluoroarenesulfonyl radicals (cf. [4]). In
We have found that the action of mixture of bromine and
fuming nitric acid on pentafluorobenzenethiol (2) affords penta-
fluorobenzenesulfonyl bromide 1 in good yield (Scheme 1).
The formation of compound 1 can also take place in the
reactions of thiol 2 with Br2, HBr, NaBr and acids (HNO3, H2SO4,
* Corresponding author. Fax: +7 383 330 9752.
E-mail address: platonov@nioch.nsc.ru (V.E. Platonov).
0022-1139/$ – see front matter ß 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2009.09.011

14
V.E. Platonov et al. / Journal of Fluorine Chemistry 131 (2010) 13–16
Table 1
Methods of synthesis of compound 1.
Method
A1
A2
B
C
D
E
F
G
H
Reagents
Fuming
HNO3 + Br2
80
HNO3 + Br2
HNO3
HNO3
Br2 + H2SO4
Br2
Br2 + H2O
NaBr
NaBr + HNO3
+ H2SO4
75–85
+ H2SO4 + Br2
+H2SO4 + HBr
75–80
+ CH3COOH
+ fuming HNO3
Temp. (8C)
Yield of 1
80
47
80
84
80–90
a
75–80
a
80–90
44a
85–95
76
87
83
67
a
The reaction mixtures obtained by methods D, E and F contained 1 alongside bis(pentafluorophenyl)disulfide 3 in the ratio (1:3, according to 19F NMR): ꢁ10:1 (method D),
ꢁ8:1 (method E), 8.3:1 (method F).
Scheme 1.
Scheme 3.
and (9) proceeded at higher temperatures. The best yields of (8)
and (9) were obtained by method B (Scheme 3).
It has been shown that the use of method C resulted in the
synthesis of polyfluoroarenesulfonyl bromides containing strong
electron-acceptor group in the ring from the corresponding
polyfluoroarenethiols in significantly low yields. For example,
nonafluoro-5-indanethiol 12 and 2,4-bis(trifluoromethyl)-3,5,6-
trifluorobenzenethiol 13 were converted to nonafluoro-5-indane-
sulfonyl bromide 14 and 2,4-bis(trifluoromethyl)-3,5,6-trifluoro-
benzenesulfonyl bromide 15 to a little extent. At the same time
methods A1 and B were used for the preparation of sulfonyl
bromide 14 in 91% yield and 69% yield respectively. Method A1 was
the most suitable one for the synthesis of 2,4-bis(trifluoromethyl)-
3,5,6-trifluorobenzenesulfonyl bromide (15) from thiol (13) and 2-
chloro-4-trifluoromethyl-3,5,6-trifluorobenzenesulfonyl bromide
(16) from thiol (17). An important application of the method A1 is
the transformation of 2,3,5,6-tetrafluoropyridinethiol (18) into the
corresponding sulfonyl bromide (19) (Scheme 4).
Electrophilic brominating agents [7] and nitronium cation [8]
take probably part in the formation of polyfluoroarenesulfonyl
bromides. The intermediates ArfSBr [9] could be formed from
polyfluoroarenethiols under action of electrophilic species. It is
possible that formation of polyfluorinated diaryl disulfides
proceeds with participation of ArfSBr (cf. [10]). Conversion of
ArfSR (R = Br, SArf) undꢀer the action of, for example, nitronium
cation or Br2 and ONO2 to ArfSO2Br could include intermediate
formation of ArfS(O)Br. The proposed route of the formation of
polyfluoroarenesulfonyl bromides from polyfluoroarenethiols and
the corresponding disulfides could be illustrated in the following
scheme (Scheme 5).
Scheme 2.
CH3COOH) or with Br2 and H2O. The results are presented in
Table 1.
These data permit us to conclude that the best result was
obtained by the reaction of compound 2 with the Br2 and fuming
nitric acid (d 1.52) (method A1). In the reactions of thiol 2 with
mixtures of concentrated nitric (d 1.36) and sulfuric (d 1.83) acids
and Br2 (method B), or concentrated nitric, sulfuric and hydro-
bromic (d 1.49) acids (method C) or suspension of sodium bromide
in fuming nitric acid (method G), the compound 1 was obtained in
good yields. The other methods mentioned in Table 1 resulted in
difficultly separable mixtures of sulfonyl bromide 1 and disulfide 3.
When thiol 2 reacted with HBr, HNO3 and H2SO4 at ꢀ20 8C,
disulfide 3 was obtained alongside sulfonyl bromide 1. Disulfide 3
was converted to sulfonyl bromide 1 (81% yield) when heated with
a mixture of Br2 and fuming HNO3 (Scheme 2).
The methods A1, B and C previously mentioned as affording
good results were used for the synthesis of new polyfluoroar-
enesulfonyl bromides. Thus, 2,3,5,6-tetrafluorobenzenethiol (4)
was converted to 2,3,5,6-tetrafluorobenzenesulfonyl bromide (5)
in 80% yield (method C). The transformation of 4-chloro-2,3,5,6-
tetrafluorobenzenethiol (6) and 4-trifluoromethyl-2,3,5,6-tetra-
fluorobenzenethiol (7) to the corresponding sulfonyl bromides (8)
This way is in agreement with the data of oxidative chlorination
of polyfluoroarenethiols into polyfluoroarenesulfonyl chlorides [6]
Scheme 4.

V.E. Platonov et al. / Journal of Fluorine Chemistry 131 (2010) 13–16
15
temperature rose to ꢁ56 8C (methods A1 and B), 30–35 8C (method
C) as a result of the exothermic reactions which ensued. Vigorous
evaluation of gas of brown color (probably nitrogen dioxide)
ensued with changing of color of mixture. After complete addition
of polyfluoroarenethiol, the resulting reaction mixture was heated
for several hours (2–5 h) and then allowed to cool to room
temperature. The mixture was poured into CH2Cl2 (25–50 mL), the
organic layer was washed with 10% aqueous solution of Na2CO3
(2ꢃ 25 mL) and dried over CaCl2. The solvent was distilled off to
give pure polyfluoroarenesulfonyl bromide.
Scheme 5.
Table 2
Molar ratios of ArfSX (X = H, SArf, 1.0 mol) to electrophilic reagents.
Compound
Method
Br2
HNO3
H2SO4
Product
Yield (%)
3
4
A1
C
8.0
2.2a
2.7
2.5
5.3
2.7
3.4
2.4
4.0
9.7
4.2
5.2
4.6
9.9
7.9
8.0
1
5
81
80
88
77
80
91
84
87
71
4.1. Pentafluorobenzenesulfonyl bromide (1)
9.8
11.2
8.5
6
B
8
7
B
9
Compound 1 was obtained following the general synthetic
procedure and using also other methods. Molar ratio (temperature,
time of reaction): 2:Br2:HNO3 (d 1.52) = 1.0:2.7:4.8 (80 8C, 2 h, 87%
yield, method A1); 2:Br2:HNO3 (d 1.36) = 1.0:2.8:4.6 (80 8C, 2 h, 47%
yield, method A2); 2:Br2:HNO3:H2SO4 = 1.0:3.2:5.3:10.4 (80 8C, 2 h,
84% yield, method B); 2:HBr:HNO3:H2SO4 = 1.0:2.0:4.1:8.1 (80 8C,
2 h, 83% yield, method C); 2:Br2:H2SO4 (d 1.83) = 1.0:3.7:8.0 (80–
90 8C, 6 h, method D); 2:Br2:CH3COOH = 1.0:4.1:16.4 (75–80 8C, 2 h,
method E); 2:Br2:H2O = 1.0:4.6:8.4 (80–90 8C, 2 h, method F);
2:NaBr:HNO3 = 1.0:2.9:8.5 (85–95 8C, 2 h, 76% yield, method G);
2:NaBr:HNO3:H2SO4 = 1.0:2.1:4.2:8.3 (75–85 8C, 2 h, 67% yield,
method H). Following the general synthetic procedure the methods
D, E and F afforded reaction mixtures which contained 1 alongside
disulfide 3 in the ratio (1:3 according to 19F NMR): ꢁ10:1 (method
D), ꢁ8:1 (method E), 8.3:1 (44% yield of 1, method F). When NaBr is
used (methods G and H) the reaction mixture is poured into CH2Cl2
and the solid residue is washed with CH2Cl2 (2ꢃ 5 mL). The CH2Cl2
solutions are combined and treated as described above.
10
12
13
17
18
A1
A1
A1
A1
A1
11
14
15
16
19
5.8
11.8
a
Molar ratio of HBr.
and the conversion of sulfenyl chloride groups containing in
polyfluorinated aliphatic polymers and alkane derivative to the
sulfonyl chlorides by reaction in CFC-113 with Cl2 in trifluoroacetic
acid and water at about 100 8C or with aqueous sodium
hypochlorite. Treatment of sulfenyl chloride derivatives of the
polymers with HOFꢂacetonitrile reagent afforded mixtures of the
corresponding sulfonyl chloride and sulfonyl fluoride derivatives
[11].
However, many details of the mechanism of the formation of
polyfluoroarenesulfonyl bromides including also the question of
participation of ArfSO2H in the formation of ArfSO2Br still remain to
be clarified.
Light-yellow oil. UV
(neat):
645, 592, 558, 538, 484 cmꢀ1
(tt, 1F4, JF
= 21, JF
C6BrF5O2S: 309.8723, found 309.8713. Anal. Calcd for C6BrF5O2S: C
23.2; F 30.5; Br 25.7; S 10.3. Found: C 23.1; F 30.4; Br 25.5; S 10.3.
lmax, nm (lg e): 219 (3.95), 278 (3.36). IR
n
1644, 1503, 1389, 1306, 1269, 1175, 1103, 1025, 997, 728,
.
19F NMR:
d
ꢀ135.6 (m, 2F2,6), ꢀ140.5
= 9), ꢀ157.7 (m, 2F3,5) [3]. Calcd for
3. Conclusion
4
3;5
ꢀF
4
2;6
ꢀF
Investigations of the reactions of polyfluoroarenethiols with
mixture of Br2 and fuming HNO3, Br2, HNO3 and H2SO4 along with
other electrophilic brominating agents expand the knowledge of
transformation of substituent groups of polyfluoroarenes under
the action of electrophilic reagents. And, although the questions of
the mechanism of these reactions are quite complex, we can hope
that a further investigation of processes of this type will promote a
solution of these problems to a more complete extent. The
appearance of available polyfluoroarenesulfonyl bromides as a
result of the investigations carried out opens up the possibilities in
the investigation of the chemistry of these compounds in different
reactions.
4.2. 2,3,5,6-Tetrafluorobenzenesulfonyl bromide (5)
Mp 51–52 8C, white crystals. UV
lmax, nm (lg e): 215 (4.04), 291
(3.43). IR (KBr): 3075, 1504, 1386, 1374, 1249, 1189, 1159, 939,
n
877, 715, 589, 555, 501, 488 cmꢀ1
.
1H NMR:
d
7.4 (tt, JHꢀF = 9.5,
3;5
JHꢀF = 7.0). 19F NMR:
d
ꢀ134.7 (m, 2F3,5), ꢀ136.6 (m, 2F2,6). Calcd
2;6
for C6HBrF4O2S: 291.8817, found 291.8824. Anal. Calcd for
C6HBrF4O2S: C 24.6; H 0.3; Br 27.3; F 25.9; S 10.9. Found: C
24.6; H 0.4; Br 27.2; F 25.7; S 10.8.
4.3. 4-Chloro-2,3,5,6-tetrafluorobenzenesulfonyl bromide (8)
4. Experimental
Mp 41–42 8C, white crystals. UV
(3.44). IR (KBr): 1631, 1493, 1459, 1395, 1373, 1270, 1170, 983,
963, 627, 567, 537 cmꢀ1 19F NMR:
2F). Calcd for C6BrClF4O2S: 325.8428. Found 325.8427. Anal. Calcd
for C6BrClF4O2S: C 22.0; Cl 10.8; F 23.2; S 9.8. Found: C 22.3; Cl
10.9; F 23.6; S 9.6.
lmax, nm (lg e): 229 (4.12), 287
19F and 1H NMR spectra were recorded on a Bruker AV-300
instrument at 282 and 300 MHz respectively for solutions in CCl4.
n
.
d
ꢀ136.2 (m, 2F), ꢀ136.7 (m,
Chemical shifts are given in
d
(ppm); the internal standards were
C6F6 (ꢀ162.9 ppm from CCl3F) and HMS (0.04 ppm from TMS). The
19F and 1H chemical shifts are reported vs. CCl3F and TMS. Coupling
constants (J) are given in Hz. IR spectra were measured on a Bruker
Vector 22 IR spectrophotometer. UV spectra were recorded on a
Hewlett Packard 8453 UV spectrophotometer for solutions in
hexane. High resolution mass spectra were recorded on the
Finnigan MAT 8200 (EI mode, 70 eV). Polyfluoroarenethiols and
disulfide 3 were synthesized according to [12,13].
General synthetic procedure: polyfluoroarenethiol (5–10 mmol)
was added dropwise to a stirred mixture of Br2 and fuming HNO3 (d
1.52) (method A1), Br2, HNO3 (d 1.36) and H2SO4 (d 1.83) (method
B) or HBr (d 1.49), HNO3 and H2SO4 (method C) (Table 2). The
4.4. 4-Trifluoromethyl-2,3,5,6-tetrafluorobenzenesulfonyl bromide
(9)
Mp 51–52 8C, white crystals. UV
(3.45). IR (KBr):
556, 525 cmꢀ1
(m, 2F2,6), ꢀ135.6 (m, 2F3,5). Calcd for C7BrF7O2S: 359.8691. Found
359.8698. Anal. Calcd for C7BrF7O2S: C 23.3; Br 22.1; F 36.8; S 8.9.
Found: C 23.3; Br 22.0; F 36.6; S 9.0.
lmax, nm (lg e): 218 (4.05), 298
n
1504, 1385, 1326, 1169, 996, 945, 717, 670, 578,
.
19F NMR:
d
ꢀ57.5 (t, 3FCF3, JCF3ꢀF = 22), ꢀ134.1
3;5

16
V.E. Platonov et al. / Journal of Fluorine Chemistry 131 (2010) 13–16
4.5. Nonafluorobiphenyl-4-sulfonyl bromide (11)
557, 521 cmꢀ1
.
19F NMR:
d
ꢀ57.8 (t, 3F, CF3, JCF3ꢀF = JCF3ꢀF = 22),
3
5
ꢀ109.9 (qd, 1F3, JF
= 13), ꢀ130.3 (quintet, 1F5, JF
= 21),
3
6
5
6
ꢀF
ꢀF
Mp 61–62 8C. UV
(KBr):
618, 563, 539 cmꢀ1
l
max, nm (lg
e
): 203 (4.36), 252 (4.15). IR
ꢀ131.3 (dd, 1F6). Calcd for C7BrClF6O2S: 375.8390. Found
375.8393. Anal. Calcd for C7BrClF6O2S: C 22.3; Br 21.2; F 30.2; S
8.5. Found: C 22.5; Br 21.4; F 30.4; S 8.2.
n
1530, 1510, 1477, 1391, 1272, 1172, 1133, 1003, 975, 726,
.
19F NMR:
d
ꢀ133.6 (m, 2F3,5), ꢀ135.6 (m,
0
0
0
2F2,6), ꢀ137.1 (m, 2F2 ,6 ), ꢀ148.6 (tt, 1F4 , JF
0
0 0
= 21,
3 ;5
4
ꢀF
0
0
JF
0
4
0 0
2 ;6
= 4), ꢀ160.4 (m, 2F3 ,5 ). Calcd for C12BrF9O2S: 457.8659,
4.9. 2,3,5,6-Tetrafluoropyridine-4-sulfonyl bromide (19)
ꢀF
found 457.8669. Anal. Calcd for C12BrF9O2S: C 31.4; Br 17.4; F 37.2;
S 7.0. Found: C 31.5; Br 17.5; F 37.2; S 6.7.
Light-yellow oil. UV
(neat):
434 cmꢀ1
C5BrF4NO2S: 292.8770. Found 292.8762. Anal. Calcd for
C5BrF4NO2S: C 20.4; Br 27.2; F 25.9; N 4.8; S 10.9. Found: C
20.7; Br 27.2; F 25.7; N 5.0; S 10.9.
lmax, nm (lg e): 203 (4.04), 298 (3.37). IR
n
1483, 1392, 1265, 1246, 1169, 968, 611, 564, 503,
4.6. Nonafluoroindane-5-sulfonyl bromide (14)
.
19F NMR:
d
ꢀ84.3 (m, 2F2,6), ꢀ137.0 (m, 2F3,5). Calcd for
Mp 40.5–42.5 8C, white crystals. UV
286 (3.49). IR (KBr):
lmax, nm (lg e): 211 (4.17),
n
1501, 1395, 1328, 1311, 1250, 1207, 1177,
1091, 957, 914, 675, 586, 535 cmꢀ1
.
19F NMR:
d
ꢀ107.6 (m, 2F1 or
2F3), ꢀ109.0 (m, 2F3 or 2F1), ꢀ110.0 (dt, 1F4, JF
= 21, JF
= 8),
= 3),
4
7
4
3
ꢀF
ꢀF
ꢀ116.3 (d, 1F6, JF
= 21), ꢀ130.5 (quintet, 2F2, JF
= JF
References
6
7
2
1
2
3
ꢀF
ꢀF
ꢀF
ꢀ135.9 (tt, 1F7, JF
= 8). Calcd for C9BrF9O2S: 421.8656. Found
7
1
ꢀF
[1] V.E. Platonov, A. Haas, M. Schelvis, M. Lieb, K.V. Dvornikova, O.I. Osina, Y.V.
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421.8659. Anal. Calcd for C9BrF9O2S: C 25.6; Br 18.9; F 40.4; S 7.6.
Found: C 25.6; Br 18.9; F 40.8; S 7.5.
[2] V.E. Platonov, A. Haas, M. Schelvis, M. Lieb, K.V. Dvornikova, O.I. Osina, T.V.
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4.7. 2,4-Bis(trifluoromethyl)-3,5,6-trifluorobenzenesulfonyl bromide
(15)
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Notes/archive.html.
Yellow oil. UV
lmax, nm (lg e): 307 (3.91). IR (neat): n 1604,
1489, 1441, 1395, 1363, 1329, 1229, 1172, 952, 878, 738, 678, 655,
581, 561, 526 cmꢀ1
.
19F NMR:
d
ꢀ50.9 (d, 3F, 2-CF3, JCF3ꢀF = 38),
3
ꢀ57.8 (dd, 3F, 4-CF3, JCF3ꢀF = 25, JCF3ꢀF = 22), ꢀ108.6 (m, 1F3),
5
3
ꢀ119.3 (m, 1F5), ꢀ125.6 (dd, 1F6, JF
= 22, JF
= 12.5). Calcd
6
5
6
3
ꢀF
ꢀF
for C8BrF9O2S: 409.8655. Found 409.8653.
4.8. 2-Chloro-4-trifluoromethyl-3,5,6-trifluorobenzenesulfonyl
bromide (16)
Yellow oil. UV
lmax, nm (lg e): 221 (3.96), 307 (3.61). IR (neat): n
1471, 1390, 1336, 1312, 1244, 1165, 1090, 954, 883, 689, 670, 574,
[13] P. Robson, M. Stacey, R. Stephens, J.C. Tatlow, J. Chem. Soc. (1960) 4754–4760.