ω-Pentafluoro-λ6-sulfanyl(SF5)-n- perfluoroalkyl benzene derivatives

Article abstract of DOI:10.1016/S0022-1139(01)00365-7

The reaction of pentafluoro-λ⁶-sulfanyl(SF₅)-perfluoroalkyl iodides with benzene is a convenient route for preparing SF₅-perfluoroalkyl benzene derivatives, SF₅(CF₂)_nC₆H₅

Full text of DOI:10.1016/S0022-1139(01)00365-7

Journal of Fluorine Chemistry 110 ꢀ2001) 1±4
Short communication
o-Penta¯uoro-l6-sulfanylꢀSF5)-n-per¯uoroalkyl benzene derivatives
Anna Marie Hodges, Rolf Winter, Javid Mohtasham, Pauline Bailey, Gary L. Gard*
Department of Chemistry, Portland State University, Portland, OR 97207-0751, USA
Received 3 November 2000; accepted 1 February 2001
Abstract
The reaction of penta¯uoro-l6-sulfanylꢀSF5)-per¯uoroalkyl iodides with benzene is a convenient route for preparing SF5-per¯uoroalkyl
benzene derivatives, SF5ꢀCF2)nC6H5 ꢀn ˆ 2, 4, 6, 8), a new class of per¯uoroalkylaromatic compounds. The preparation and
characterization of these new materials are described. # 2001 Elsevier Science B.V. All rights reserved.
Keywords: SF5ꢀCF2)n-aromatics; Per¯uoroalkylaromatics; NMR and IR spectroscopy; Mass spectrometry
1. Introduction
2. Results and discussion
The per¯uoroalkylation of aromatic compounds has been
accomplished through the thermolysis of per¯uoroalkyl
iodides in the presence of the appropriate aromatic com-
pound. In l960, G.V.D. Tiers described a general procedure
for the direct introduction of a per¯uoroalkyl group ꢀRf) into
benzene and other aromatic compounds [1]. Other workers
have extended the scope of this reaction using other aromatic
compounds and iodides [2]. The introduction of an SF5-
group into an aromatic system was ®rst reported in 1962 [3];
aryl disul®des or arylsulfur tri¯uorides are ¯uorinated using
AgF2. The parent compound, SF5C6H5 ꢀpenta¯uorothioben-
zene or phenylsulfur penta¯uoride or penta¯uoro-l6-sulfa-
nyl benzene) can also be prepared in low yields by the
thermal reaction of S2F10 with benzene [4]. In a more recent
report, the use of elemental ¯uorine was described [5]. A
multistep method involving SF5CBCH has been reported as a
pathway to SF5C6H5 [6]. The photolysis of SF5CBCH with
SF5Cl or the reaction of SF5CBCH with Co2ꢀCO)8 and
bromine have produced SF5-trisubstituted derivatives of
benzene [7].
The introduction of the SF5ꢀCF2)n ꢀn ˆ 2, 4, 6, 8) group
into benzene was accomplished via the following thermal
reaction:
D
SF5ꢀCF2†nI ‡ xsC6H6!SF5ꢀCF2†nC6H5 ‡ by-products
For n ˆ 2 ꢀ1), the yield of the reaction and the amount of by-
products ꢀcharacterized by GC±MS) formed proved to be
highly dependent upon reaction conditions.
In Section 3, the experimental conditions that minimize
the production of by-products are given. The optimum
conditions were 72 h at 1458C and resulted in a pure product
with a yield of 39%. For the n ˆ 4 ꢀ2) homologue, a yield of
50% was obtained. A GC±MS study of the reaction of
SF5ꢀCF2)6I with benzene showed that 51% of the starting
iodide was converted to product, SF5ꢀCF2)6C6H5 ꢀ3). In one
reaction, using SF5ꢀCF2)nI ꢀa mixture containing n ˆ 6 and
8), both the SF5ꢀCF2)6C6H5 and SF5ꢀCF2)8C6H5 were
obtained and characterized by GC±MS.
The infrared spectra of the new SF5ꢀCF2)nC6H5 com-
pounds ꢀfor n ˆ 2, 4) have in common the characteristic
absorption bands of the SF5-group. Cross and coworkers
found that the most intense band attributed to the SF5-group
appears in the region 850±920 cmÀ1 ꢀS±F stretching modes)
with one of the S±F deformation modes in the region of
600 cmÀ1 [15]. For the new compounds reported in this
paper, the stretching and deformation bands are found in the
808±888 cmÀ1 and 606±599 cmÀ1 ranges, respectively. The
stretching vibrations for the CF2-groups give rise to strong
absorption bands in the 1105±1287 cmÀ1 region; these
We have recently developed an interest in aromatic
compounds containing the SF5-group because of the unique
properties that the SF5-group can confer upon organic
systems. These properties include high dielectric strength,
high thermal stability, high chemical resistance, low refrac-
tive index and low surface free energy [6,8±14].
* Corresponding author. Fax: ‡1-503-7253888.
E-mail address: psu20653@pdx.edu ꢀG.L. Gard).
0022-1139/01/$ ± see front matter # 2001 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 1 1 3 9 ꢀ 0 1 ) 0 0 3 6 5 - 7

2
A.M. Hodges et al. / Journal of Fluorine Chemistry 110 ,2001) 1±4
stretching modes are normally found in the 1100±
1400 cmÀ1 region [16]. The 19F-NMR spectra for the com-
pounds ꢀn ˆ 2, 4) show an AB4 pattern for the SF5-group: A
ꢀdistorted pentet or nine-line pattern) at j ˆ 65:2±
66.1 ppm; B ꢀdoublet) at j ˆ 45:1 ppm. For SF5CF2CF2I
and other SF5-¯uoroalkyl derivatives, the chemical shifts are
located at j ˆ 67:2±64.0 and 44.2±47.3 ppm, respectively
[17]. The chemical shifts of the CF2 ¯uorines adjacent to the
SF5-group are located in the range j ˆ À93:8±96.5 ppm;
for other SF5CF2CF2-¯uoroalkyl derivatives this range is
À97.5 to À89.0 ppm [17]. The CF2 ¯uorines adjacent to the
benzene ring are present at À111.5 ppm for n ˆ 2, at
À112.0 ppm for n ˆ 4; by comparison, the chemical shifts
of the ¯uorines of the CF2-group in m-CF3CF2C6H4X
ꢀX ˆ F, NO2, NH2) are found at À115.5 to À115.9 ppm
[18].
in order to avoid any condensation of the reagents. After
cooling, the reaction mixture was poured into a separatory
funnel and the vessel was rinsed with about 10 ml of diethyl
ether. The mixture was washed with sodium bisul®te ꢀthree
times, using about 40±50 ml of a saturated solution
each time), sodium bicarbonate ꢀthree times, using about
40±50 ml of a saturated solution each time) and water ꢀabout
50±60 ml), then dried over magnesium sulfate. The lower
boiling materials were distilled away at atmospheric pres-
sure. Distillation of the residue at low pressure gave 3.42 g
ꢀ11.25 mmol) of the colorless liquid SF5CF2CF2C6H5, boil-
ing point 85±878C/44 Torr, yield was 39%. The retention
time via GC±MS analysis was 6.10 min.
The infrared spectrum shows the following bands ꢀcmÀ1):
3075 ꢀw); 3052, ꢀvw), 1965, ꢀvw), 1904 ꢀvw), 1814 ꢀvw),
1775 ꢀvw), 1608 ꢀw), 1500 ꢀmw), 1457 ꢀms), 1325 ꢀvw),
1276 ꢀs), 1258 ꢀm), 1243 ꢀm), 1199 ꢀs), 1167 ꢀms), 1116 ꢀvs),
1095 ꢀm), 1073 ꢀms), 1046 ꢀmw), 1030 ꢀmw), 1023 ꢀmw),
1004 ꢀvw), 947 ꢀm), 933 ꢀmw), 923 ꢀmw), 875 ꢀvs), 825 ꢀs),
808 ꢀvs), 758 ꢀs), 701 ꢀs), 677 ꢀs), 660 ꢀms), 642 ꢀw), 606, ꢀs),
584 ꢀm), 574 ꢀs), 484 ꢀw), 417 ꢀmw).
The major mass spectral peaks as well as relative retention
times for SF5ꢀCF2)nC6H5, ꢀn ˆ 2, 4, 6, 8) are listed in
Section 3. Molecular ion peaks are observed for all new
compounds. A GC±MS study allowed us to clearly separate
and identify each new compound; for n ˆ 6, 8 only GC±MS
results are given.
A molecular ion peak and appropriate fragments were
observed in the mass spectrum. Major peaks include ꢀm/z,
‡
‡
molecular ion, relative %): 304 ꢀM , 18%), 177 ꢀSF5CF2 or
ꢀM±SF5) , 12%), 158 ꢀSF5CF or C6H5CF2CF , 4%), 127
‡ ‡ ‡
3. Experimental
‡
‡
‡
‡
ꢀSF5 or C6H5CF2 , 100%), 107 [ꢀC7H4F) , 3%), 89 [SF3
‡
‡
‡
‡
3.1. Starting materials
or ꢀC7H5) , 3%], 77 ꢀC6H5 , 10%), 51 ꢀSF or C4H3 , 4%).
The 19F-NMR ꢀCFCl3) of FaÀSFb4ÀCFc2ÀCF2dÀC6H5
shows the following peaks: ja ꢀ66.1 ppm, p, m), jb
ꢀ45.1 ppm, d, p), jc ꢀÀ93.8 ppm, m), jd ꢀÀ111.5 ppm,
The SF5-per¯uoroalkyl iodides were prepared from S2F10,
ICF2CF2I, and CF2=CF2 [17,19±21]; benzene was obtained
from E. Merck and was used as received.
m). The coupling constants were as follows: Ja;b
ˆ
NMR-spectra were recorded with a Varian EM-390 spec-
trometer operating at 84.67 MHz for 19F-analysis; a Bruker
146:3 Hz, Ja;c ˆ 4:7 Hz, Jc;d ˆ 12:2 Hz, and Jb,c and Jb,d
were between 13.4 and 14.5 Hz. The integration values for
FSF4CF2CF2 were a ˆ 1:0; b ˆ 3:9; c ˆ 2:0; d ˆ 2:0.
The 1H-NMR spectrum ꢀ500 MHz, CDCl3) of
shows the following peaks:
1
AMX-400 spectrometer operating at 400 MHz for H-ana-
lysis, and 376.5 MHz for 19F-analysis; CCl3F and ꢀCH3)4Si
were used as internal standards. The IR-spectra were
obtained between potassium bromide plates using a Perkin-
Elmer System 2000 FT-IR operating at 2 cmÀ1 resolution.
Elemental analyses were determined by Beller, Mikroana-
dei ˆ 7:57 ppm ꢀd), dfh ˆ 7:43 ppm ꢀt), dg ˆ 7:51 ppm ꢀt),
and the coupling constants were as follows: Je;f  Jh;i
7:76 Hz, and Jf;g  Jg;h ˆ 7:31 Hz.
ˆ
È
lytisches Laboratorium, Gottingen, Germany. Mass spectra
Analysis: calculated for C8H5F9S: C, 31.58; H, 1.64; F,
56.3; S, 10.53%. Found: C, 31.41; H, 1.70; F, 55.8; S,
10.37%.
were obtained using a Hewlett-Packard HP5890 series II gas
chromatograph ꢀ25 m, DB-5 column) with a HP5970 mass-
selective detector operating at 70 eV. The temperature pro-
gram was such that t ˆ 508C for 2 min, then the temperature
was raised to 2808C at 118C/min; injection port temperature
was 2508C.
3.3. Preparation of SF5,CF2)4C6H5 ,2)
Into 210 ml Pyrex-glass Carius tube equipped with a
Kontes Te¯on stopcock, 10.45 g ꢀ23.01 mmol) of
SF5ꢀCF2)4I, and 91 g ꢀ1166.7 mmol) of C6H6 were added.
The reaction vessel was cooled to À1968C and evacuated.
The reaction mixture was heated at 180±1858C for 16 days
during which time periodic measurements of the progress of
the reaction were checked via GC±MS. At the end of the
reaction time, the contents of the Carius tube were trans-
ferred into a 500 ml beaker and washed in a similar fashion
to that described above with saturated solutions of sodium
bisul®te and sodium bicarbonate in order to remove iodine
3.2. Synthesis of SF5CF2CF2C6H5 ,1)
Into a 350 ml Carius tube equipped with a Te¯on coated
stirring bar, 10.34 g ꢀ29.21 mmol) of SF5CF2CF2I and 110 g
ꢀ1408.21 mmol) of C6H6 were added. The vessel was cooled
to À1968C and evacuated to remove air. After the reaction
mixture warmed to room temperature, the lower part of the
vessel was heated for 72 h at 1458C. The top part of the
Carius tube was covered with glass wool and aluminum foil,

A.M. Hodges et al. / Journal of Fluorine Chemistry 110 ,2001) 1±4
3
and HI, then dried over magnesium sulfate; lower boiling
3.5. Preparation of SF5,CF2)6C6H5 ,3) and
SF5,CF2)8C6H5 ,4)
materials were removed via distillation at atmospheric
pressure. Distillation of the residue, at reduced pressure,
gave 4.63 g ꢀ11.5 mmol) of SF5ꢀCF2)4C6H5, boiling point
90±958C/20 Torr, yield was 50%. The retention time via
GC±MS analysis was 7.59 min.
The infrared spectrum of SF5ꢀCF2)4C6H5 shows the
following bands ꢀcmÀ1): 3080 ꢀw), 3050 ꢀvw), 1988 ꢀvw),
1967 ꢀvw), 1912 ꢀvw), 1897 ꢀvw), 1612 ꢀw), 1502 ꢀmw),
1457 ꢀms), 1313 ꢀw), 1287 ꢀs), 1218 ꢀvs), 1175 ꢀs), 1151 ꢀvs),
1105 ꢀs), 1074 ꢀms), 1033 ꢀmw), 1054 ꢀmw), 963 ꢀs), 952 ꢀs),
922 ꢀs), 888 ꢀvs), 859 ꢀvs), 808 ꢀmw), 787 ꢀs), 768 ꢀvs),
741 ꢀs), 727 ꢀs), 711 ꢀs), 698 ꢀvs), 685 ꢀs), 676 ꢀs), 640 ꢀs),
599 ꢀs).
Into a 50 ml Pyrex-glass Carius tube equipped with a
Kontes Te¯on stopcock, 0.53 g mixture of SF5ꢀCF2)6I and
SF5ꢀCF2)8I, and 2.34 g ꢀ30.0 mmol) of C6H6 were added.
The reaction vessel was cooled to À1968C and evacuated.
The reaction mixture was then heated at 160±1658C for 14
days during which time periodic measurements of the
reaction completion were checked by GC±MS. At the end
of the reaction time, the volatile materials of the reaction
were pumped through a trap at À1968C and the excess
amount of benzene was removed through distillation at
atmospheric pressure. A representative sample of the pot
residue was analyzed via GC±MS and SF5ꢀCF2)6C6H5
ꢀretention time of 9.20 min) and SF5ꢀCF2)8C6H5 ꢀretention
time of 10.59 min) were found to be present.
A molecular ion peak and appropriate fragments were
observed in the mass spectrum. Major peaks include ꢀm/z,
‡
‡
molecular ion, relative %): 404 ꢀM , 10%), 277 [M±SF5 or
‡
‡
SF5ꢀCF2)3 13%], 257 ꢀM±SF5±HF , 4%), 227
‡
[SF5ꢀCF2)2 or M±SF5CF2 , 3%], 177 [SF5CF2 or
,
The molecular ion peak and appropriate fragments were
observed in the mass spectrum for SF5ꢀCF2)6C6H5; these
values are reported above. A molecular ion peak and appro-
priate fragments were observed in the mass spectrum
of SF5ꢀCF2)8C6H5. Major peaks include ꢀm/z, molecular
‡
‡
‡
‡
‡
C6H5ꢀCF2)2 , 2%], 158 ꢀC6H5C2F3 or SF5CF ), 127
‡
‡
‡
‡
ꢀSF5 or C6H5CF2 , 100%), 107 ꢀC7H4F , 2%), 89 ꢀSF3
‡
‡
‡
or C7H5 , 3%), 77 ꢀC6H5 , 8%), 51 ꢀSF , 3%).
‡ ‡
The 19F-NMR ꢀCFCl3) of FaÀSFb4ÀCF2cÀCF2dÀCF2eÀ
ion, relative %): 604 ꢀM , 2%), 585 ꢀM±F , 2%), 477
‡
CFf ÀC6H5 shows the following peaks: ja ꢀ65.2 ppm, m),
[SF5ꢀCF2)7 or M±SF5 , 3%], 457 ꢀM±SF5±HF , 1%),
‡ ‡
‡
‡
2
jb ꢀ45.1 ppm, d), jc ꢀÀ96.5 ppm, m), jd and je ꢀ122.5±
123.5 ppm, m), and jf ꢀ112.0 ppm, m). The relative integra-
tion areas for FSF4CF2ꢀCF2CF2)CF2 were a ˆ 1:0; b ˆ 4:0;
c ˆ 2:0; d ‡ e ˆ 3:8; f ˆ 2:0.
427 [SF5ꢀCF2)6 or M±SF5CF2 , 1%], 358 [M±SF5±
‡
‡
‡
‡
C2F5 , SF5ꢀCF2)4CF , <1%], 208 [SF5CF2CF , C6H5
‡
‡
ꢀCF2)2CF , 2%], 177 [SF5CF2 or C6H5ꢀCF2)2 , 3%],
‡
‡
‡
‡
158 ꢀSF5CF , C6H5CF2CF , 5%), 127 ꢀSF5 or C6H5CF2 ,
‡
‡
‡
Analysis: calculated for C10H5F13S: C, 29.72; H, 1.25;
F, 61.1; S, 7.94%. Found: C, 29.52; H, 1.10; F, 60.7; S,
8.04%.
100%), 107 ꢀC7H4F , 1%), 77 ꢀC6H5 , 4%), 51 ꢀSF , 1%).
Acknowledgements
3.4. Preparation of SF5,CF2)6C6H5 ,3)
We are grateful to the National Science Foundation
ꢀCHE-9904316) and the Petroleum Research Foundation
ꢀACS-PRF number 34624-AC7) for support of this work.
Into a 50 ml Pyrex-glass Carius tube equipped with a
Kontes Te¯on stopcock, 0.58 g ꢀ1.05 mmol) of SF5ꢀCF2)6I,
and 3.1 g ꢀ39.74 mmol) of C6H6 were added. The reaction
vessel was cooled to À1968C and evacuated. The reaction
mixture was heated at 160±1658C for 14 days during which
time periodic GC±MS measurements were made in order to
determine the progress of the reaction. After 14 days, the
volatile materials were pumped through a À1968C trap;
excess benzene was removed by distillation at atmospheric
pressure. A GC±MS study of the pot residue showed 51%
conversion into SF5ꢀCF2)6C6H5; retention time was
9.20 min.
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‡
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‡
‡
‡
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‡
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‡
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‡
‡
‡
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‡
‡
‡
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‡
‡
‡
‡
ꢀC7H4F , 1%), 89 ꢀSF3 or C7H5 , 3%), 77 ꢀC6H5
‡
,
6%), 51 ꢀSF , 2%).

4
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