2,5-Dichloro-1-(ROSO2)benzene [R = C6H5, C6F5, and CH2(CF2)4H]: Synthesis, molecular structure, and solubility in supercritical CO2

Article abstract of DOI:10.1016/j.jfluchem.2005.12.014

Highly crystalline phenyl 2,5-dichlorobenzenesulfonate (PDBS, T _melt = 86-87°C) and pentafluorophenyl 2,5- dichlorobenzenesulfonate (FPDBS, T_melt = 120-122°C) were synthesized. Single-crystal X-ray molecular structure determinations

Full text of DOI:10.1016/j.jfluchem.2005.12.014

Journal of Fluorine Chemistry 127 (2006) 330–336
www.elsevier.com/locate/fluor
2,5-Dichloro-1-(ROSO2)benzene [R = C6H5, C6F5, and CH2(CF2)4H]:
Synthesis, molecular structure, and solubility in supercritical CO2
a
b
Michael E. Wright a, , Casey E. Gorish , Zhihao Shen , Mark A. McHugh
*
b,**
a Research Department, Chemistry Division, NAWCWD-US NAVY, China Lake, CA 93555-6100, United States
b Department of Chemical and Life Science Engineering, Virginia Commonwealth University,
601 West Main Street, Richmond, VA 23284, United States
Received 20 September 2005; received in revised form 7 December 2005; accepted 12 December 2005
Available online 7 February 2006
Abstract
Highly crystalline phenyl 2,5-dichlorobenzenesulfonate (PDBS, Tmelt = 86–87 8C) and pentafluorophenyl 2,5-dichlorobenzenesulfonate
(FPDBS, Tmelt = 120–122 8C) were synthesized. Single-crystal X-ray molecular structure determinations show that both compounds have similar
three-dimensional molecular structures; however, PDBS crystals are thin platelets and FPDBS crystals form hexagonal tube-like structures that are
predominately hollow at one end. PDBS crystals exhibit offset p-stacking of the phenoxy-rings that form complete two-dimensional layers each
˚
two molecules thick. Hydrogen-bonding interactions are calculated at ꢀ3.2 A between the C6-hydrogen and the sulfonyl-oxygen of a neighboring
molecule. On the other hand, for FPDBS, p-stacking of the dichloro-substituted ring as well as dipole–dipole interactions of the fluorinated-
phenoxy rings appears to be the predominate intermolecular interactions. Neither structure exhibits any kind of side-on interaction of the phenyl
rings. PDBS and FPDBS exhibit melting point depressions of 26 and 40 8C, respectively, in the presence of supercritical CO2. Although both
sulfonates exhibit high solubility in CO2, much lower pressures are needed to dissolve FPDBS compared to PDBS. For example, at 100 8C FPDBS
dissolves at 4750 psia and PDBS dissolves at 11,000 psia. The solubility data reinforce the observation that fluorinating a compound can
significantly lower the conditions needed to dissolve that compound in CO2.
# 2006 Elsevier B.V. All rights reserved.
Keywords: Supercritical CO2 solubility; Crystal engineering; Fluorination effects
1. Introduction
on fluorine content, especially when the solute is a polymer.
For example, partially or fully fluorinating a hydrocarbon
polymer, such as poly(ethylene-co-propylene) (EP), renders
the resultant fluorinated EP polymer soluble in CO2 [5].
Although it is also important to note that the polymer must have a
measurablepolarmomenttoensurethatitdissolvesinCO2 atlow
pressures and temperatures [4–7]. Specific CO2–fluorocarbon
interactions that lead to enhanced solubility have been elucidated
with high-pressure, fluorine NMR for mixtures of low molecular
weight fluorocarbons with CO2 [8] and for mixtures of
fluorinated polymers and copolymers with CO2 [9]. In addition,
ab initio molecular orbital energy calculations predict the
formation of a favorable CO2–fluorine, quadrupole–dipole
interaction stronger than that found with dispersion-type
interactions [10,11].
The replacement of hydrogen by fluorine in organic
compounds often leads to a dramatic change in chemical and
physical properties. In 1960 Patrick and Prosser [1] discovered
that a fluorinated benzene ring forms a unique p-stacking
crystalline motif with non-fluorinated benzene compounds.
Since that time many organic fluorinated-aromatic structures
have shown this type of behavior [2,3]. Furthermore, fluorination
has a pronounced effect on the interaction of the fluorinated
molecule with a solvent and this often leads to dramatic changes
in solubility [4]. Supercritical CO2, in particular, is a solvent that
exhibits a high degree of discrimination between solutes based
Recently we published a study that reported on the
pronounced effect of fluorination on the solubility and phase
behavior of rigid-rod polymers in supercritical fluids [7]. As a
part of that polymer study we also determined the effect of
* Corresponding author. Fax: +1 760 939 1617.
** Corresponding author. Tel.: +1 804 827 7031; fax: +1 804 828 3846.
E-mail addresses: michael.wright@navy.mil (M.E. Wright),
mmchugh@vcu.edu (M.A. McHugh).
0022-1139/$ – see front matter # 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2005.12.014

M.E. Wright et al. / Journal of Fluorine Chemistry 127 (2006) 330–336
331
Table 1
fluorination on the solubility of the monomers [12] and related
aromatic dimers of these rigid-rod polymers [13]. Once again,
fluorinating the monomers and dimers significantly increased
their solubility in supercritical CO2. In this paper we describe
the synthesis of new fluorinated monomers and report on their
behavior in the solid state and their solubility in supercritical
CO2 with a direct comparison to their non-fluorinated analogs.
Summary of crystal data and structure refinement for compounds 1a and 1b
Empirical formula
C12H8Cl2O3S
C12H3Cl2F5O3S
Formula weight
Space group
Crystal system
Z
˚
a (A)
˚
b (A)
303.10
393.06
P21/n
P21/n
Monoclinic
4
Monoclinic
4
9.5415(19)
8.4330(17)
16.1286(32)
106.090(30)
1246.93
1.615
5.9592(12)
11.0145(22)
21.0387(42)
95.054(30)
1375.56
1.898
2. Results and discussion
˚
c (A)
b (8)
3
˚
V (A )
2.1. Chemical synthesis and molecular structure
r (calc) (g/cm3)
mcalc (mmꢁ1
)
0.68
0.69
Phenyl 2,5-dichlorobenzenesulfonate (PDBS) [14] and
pentafluorophenyl 2,5-dichlorobenzenesulfonate (FPDBS) are
prepared in high yield from the inexpensive and commercially
available 2,5-dichlorobenzenesulfonyl chloride, which has
proven a valuable synthetic launching point for several poly
( p-phenylene) monomer syntheses prior to this work [15].
˚
Radiation (Mo Ka) (A)
T (K)
0.71073
298(2)
0.71073
298(2)
u–2u range (8)
3–50
3–50
Final R1 indices [I > 4s(I)]a
Final wR2 indices (all data)a
Largest diff. peak and hole (einstein A
0.0393
0.0695
0.1056
0.1734
ꢁ3
˚
)
0.20 and ꢁ0.29 0.57 and ꢁ0.65
ꢀ
P
P
P
P
2
2 2
a
R1 ¼ jjFoj ꢁ jFcjj= jFoj and wR2 ¼
½wððFoÞ ꢁ ðFcÞ Þ ꢂ= ½w
2
2
1=2
ððFoÞ Þ ꢂÞ
.
rings, bond lengths, and angles are very similar. However,
PDBS and FPDBS exhibit crystal morphologies that are very
different from one another. PDBS crystals are thin platelets that
stack several layers thick and have an appearance very similar
to mica where thin sheets appear to be stacked upon one
another. Whereas FPDBS crystals form very distinctive
hexagonal tube-like structures that are predominately hollow
at one end (Fig. 2). These observations suggest that these
compounds adapt unique molecular packing that results in such
intriguing macromolecular shapes. In Fig. 3 we show the
packing diagrams for the two compounds that provides insight
into the dramatic differences in crystal morphology.
Compounds 1a and 1b are both isolated as highly crystalline
materials exhibiting well-defined melting points. Compound 1c
was isolated as a clear oil after distillation at reduced pressures.
All three compounds gave spectroscopic and analytical data
consistent with the proposed structures. Compounds 1a and 1b
each formed single-crystals suitable for analysis by X-ray
diffraction. Table 1 summarizes the crystal and refinement data
used in the two molecular structure determinations. Fig. 1
shows a representation of the molecular structures of PDBS and
FPDBS obtained from the single-crystal molecular structure
determinations. Both compounds have virtually identical
conformations and the relative orientation of the phenoxy-
The effect of fluorination in aromatic compounds on
molecular structure is well understood at this time due to
some very eloquent studies, both from an experimental and
theoretical point of view [2]. When looking at the packing
arrangement for 1a it is interesting to find complete two-
dimensional planes that are defined by an offset p-stacking of
Fig. 1. Molecular structure of phenyl 2,5-dichlorobenzenesulfonate (PDBS) (left) (1a) and pentafluorophenyl 2,5-dichlorobenzenesulfonate (FPDBS) (right) (1b).
Non-hydrogen atoms in the molecular structures are represented by thermal ellipsoids (30% probability) and hydrogen atoms are omitted for clarity.

332
M.E. Wright et al. / Journal of Fluorine Chemistry 127 (2006) 330–336
Table 2
Isopleth data, solution densities, and the type of transition for solutions of the
phenyl 2,5-dichlorobenzenesulfonate (PDBS) in CO2
x (wt.%)
T (8C)
P (psia)
Solution density (g/cm3)
Transition
1.9
38.7
49.4
60.4
65.5
83.6
97.7
3315
2600
2850
2995
3450
3690
0.873
0.784
0.739
0.726
0.681
0.637
S
S
S
DP
DP
DP
10.0
91.4
78.8
68.6
56.4
7725
7935
8190
8535
0.925
0.960
0.989
1.025
DP
DP
DP
DP
18.3
24.7
96.7
82.5
68.1
10203
10708
11387
1.007
1.045
1.082
DP
DP
DP
Fig. 2. Photograph of a crystal of pentafluorophenyl 2,5-dichlorobenzenesul-
fonate (1b) showing the hollow, tubular-like morphology of the crystal habit.
93.9
86.7
77.6
70.9
67.7
11258
11491
11987
12304
12383
1.101
1.115
1.139
1.155
1.163
DP
DP
DP
DP
DP
the phenoxy-rings. In addition, weak hydrogen-bonding inter-
˚
actions (calculated at ꢀ3.2 A) appear to be present between the
C6-hydrogen and the sulfonyl-oxygen of a neighboring
molecule. This interaction is not observed in the molecular
packing for 1b. For the molecular packing in 1b it appears that
p-stacking of the dichloro-substituted ring is important as well
as a possible dipole–dipole interaction of the fluorinated-
phenoxy rings. What is clearly absent in the two structures is
any kind of perpendicular interaction of two phenyl rings.
Several attempts at polymerizing compounds 1a–1c were
made using nickel-catalysis and stoichiometric zinc. We have
previously shown that 2,5-dichlorosulfonyl monomers do
nicely polymerize under these conditions [15]; however, for
each of the monomers prepared in this study we were unable to
isolate a poly-p-phenylene product for further analysis.
DP is a dew point and S is a solidification point.
2.2. Crystal phase behavior
Tables 2 and 3 list the isopleths, solution densities, and the
type of transitions for PDBS–CO2 and FPDBS–CO2 mixtures
investigated in this study from approximately room tempera-
ture to 100 8C. Since compound 1c was isolated as a clear oil
after distillation at reduced pressure, companion solubility
studies with crystalline 1a and 1b were not performed. The
pressure–temperature (P–T) data points are averaged values
of at least two independent measurements. Smooth curves are
Fig. 3. Packing diagram found for phenyl 2,5-dichlorobenzenesulfonate (1a, PDBS) (left) and pentafluorophenyl 2,5-dichlorobenzenesulfonate (1b, FPDBS) (right).
Hydrogen atoms have been omitted for clarity and atoms in the packing diagram are represented by spheres and are not representative of electron density. The packing
diagram for PDBS shows the plane between molecular layers running horizontal and into and out of the page. The packing diagram on the right shows the dipole–
dipole interactions of the fluorinated-phenyl rings.

M.E. Wright et al. / Journal of Fluorine Chemistry 127 (2006) 330–336
333
Table 3
Isopleth data, solution densities, and the type of transition for solutions of the
pentafluorophenyl 2,5-dichlorobenzenesulfonate (FPDBS) in CO2
x (wt.%)
T (8C)
P (psia)
Solution
density (g/cm3)
Transition
2.1
23.3
39.4
60.9
66.6
71.2
87.5
98.1
2505
2170
2325
2350
2415
2770
2900
0.887
0.794
0.666
0.623
0.602
0.563
0.530
S
S
S
S
DP
DP
DP
8.4
45.9
56.1
63.1
70.8
77.9
85.7
95.8
5363
3675
3400
3070
3320
3510
3790
0.974
0.879
0.829
0.768
0.752
0.733
0.714
S
Fig. 5. ComparisonoftheCO2 solubilityofphenyl2,5-dichlorobenzenesulfonate
S
(1a) obtained in this study to that reported for octyl-2,5-dichlorobenzoate [12].
S
DP
DP
DP
DP
are observed and at low temperatures fluid ! solid + fluid
transitions are observed. Even though neat PDBS melts at
86 8C, it remains a liquid in the presence of CO2 to tempe-
ratures as low as ꢀ60 8C. At concentrations of 10 wt.% and
higher the P–T isopleths exhibit negative slopes even though
the density of pure CO2 decreases with increasing temperature
which should result in higher, not lower, transition pressures.
The negative slopes of these P–T isopleths are likely due to a
faster decrease in the strength of PDBS–PDBS polar inter-
actions relative to either CO2–CO2 interactions or PDBS–CO2
interactions. At high temperatures dispersion-type interactions,
which are fixed by a component’s polarizability, become more
dominant relative to polar interactions [16]. However, CO2 has
a polarizability similar to that of methane, which means the
non-polar character of CO2 is similar to methane suggesting
that dispersion interactions between PDBS and CO2 will be of
modest strength, at best. Even though the interchange energy is
more favorable for dissolution of PDBS in CO2 at high
temperatures, elevated pressures are needed to obtain
sufficiently high CO2 densities to magnify the weak dispersion
interactions. Fig. 4 shows that pressures in excess of 8000 psia
are needed to dissolve significant amounts of PDBS.
23.4
32.3
56.0
62.9
68.0
72.0
77.9
94.6
9195
4435
3965
3640
3915
4437
1.112
0.983
0.944
0.912
0.909
0.877
S
S
S
DP
DP
DP
95.4
80.6
73.2
70.6
4563
4105
3845
3920
0.938
0.966
0.967
0.974
DP
DP
DP
S
DP is a dew point and S is a solidification point.
fit to the constant-composition (isopleth) P–T data, which are
then cross-plotted to generate pressure–composition (P–x)
isotherms. The shape of the P–T isopleth is fixed by the
interchange energy of the system, which is equal to the
difference between solute–CO2 cross-interactions and 1/2 the
sum of solute–solute + CO2–CO2 self-interactions. The
strength of self- and cross-interactions is inversely proportional
to temperature since the two sulfonate compounds have dipole
moments and CO2 has a quadrupole moment [16].
Fig. 5 shows that pressures up to 12,000 psia are needed to
dissolve significant amounts of PDBS in CO2 at 75 and 100 8C
and that there is very little difference in the P–x isotherms at
Fig. 4 shows the P–T curves for the PDBS–CO2 system.
Note that at high temperatures fluid ! liquid + fluid transitions
Fig. 4. Pressure–temperature isopleths of CO2 + phenyl 2,5-dichlorobenzene-
sulfonate (1a) at 1.9, 10.0, 18.3, and 24.7 wt.%. The open symbols denote
fluid ! liquid + fluid transition and the filled symbols denote fluid ! solid +
fluid transitions.
Fig. 6. Pressure–temperature isopleths of CO2 + pentafluorophenyl 2,5-
dichlorobenzenesulfonate (1b) at 2.1, 8.4, 23.4, and 32.3 wt.%. The open
symbols denote fluid ! liquid + fluid transition and the filled symbols denote
fluid ! solid + fluid transitions.

334
M.E. Wright et al. / Journal of Fluorine Chemistry 127 (2006) 330–336
Fig. 7. CO2 + pentafluorophenyl 2,5-dichlorobenzenesulfonate (1b) pressure–
composition isotherms at 75 and 100 8C.
Fig. 8. Impact of fluorination on the pressures needed to dissolve phenyl 2,5-
dichlorobenzenesulfonate in CO2 at 100 8C.
these two temperatures. Also shown in Fig. 5 is the 75 8C
isotherm for octyl-2,5-dichlorobenzoate (ODB), which has a
molecular weight of 303, essentially equal to that of PDBS. At
concentrations near 25 wt.% the ODB isotherm is at 7000 psia
lower pressure. This decrease in pressure can be attributable to
both the octyl chain on the ODB relative to the phenyl group and
to the ester relative to the sulfonate group. Aromatic compounds
easily dissolve in CO2 since both of these components have
quadrupole moments so that polar interactions are favorable
between CO2 and aromatics. However, the aromatic ring in
PDBS adjacent to the sulfonate is not expected to adapt as many
different configurations as the octyl-tail in ODB, which means
that it will be more difficult to dissolve PDBS than ODB due to
entropic, or free volume, considerations. In addition, the spectro-
scopic evidence in the literature suggests that CO2 interacts
favorably with ester groups, which promotes solubility [17].
The solubility behavior of FPDBS in CO2 differs
considerably from that observed with PDBS. Fig. 6 shows
the P–T curves for the FPDBS–CO2 system. Once again, at high
temperatures fluid ! liquid + fluid transitions are observed and
at low temperatures fluid ! solid + fluid transitions are
observed. In this instance the normal melting point of FPDBS,
110 8C, is reduced to ꢀ70 8C in the presence of CO2, which is a
larger melting point depression than that observed with PBDS.
The P–x isotherms in Fig. 7 show that significant amounts of
FPDBS dissolve in CO2 at pressures less than 5000 psia. Fig. 8
shows the very large difference in pressures needed to dissolve
non-fluorinated and fluorinated PDBS in CO2 at 100 8C. It is
not surprising that fluorinated PDBS is easier to dissolve in CO2
since, as mentioned previously, fluorinating a compound can
significantly lower the conditions needed to dissolve that
compound in CO2. It is important to recognize that solution
density modulates the strength of the intermolecular forces
between the different components in solution [16]. The density
data in Tables 2 and 3 show that FPDBS–CO2 solutions have
lower densities than PDBS–CO2 solutions, which is another
indication of the impact of favorable fluorine–CO2 interactions.
as a synthetic launching point for several poly( p-phenylene)
monomer syntheses. PDBS and FPDBS are prepared in high
yield, with well-defined melting points, virtually identical
conformations, and similar relative orientation of the phenyl
rings, bond lengths, and bond angles. However, fluorinating the
aromatic ring changes the crystal structure of PDBS from thin
platelets, stacked several layers thick to crystals with very
distinctive hexagonal tube-like structures that are predomi-
nately hollow at one end for FPDBS. It is interesting that neither
crystal structure exhibits any kind of side-on interaction of the
phenyl rings.
Both PDBS and FPDBS are very soluble in supercritical
CO2, although much higher pressures are needed to dissolve
PDBS compared to FPDBS. In the liquid–liquid region of the
phase diagram it is apparent that CO2 is also very soluble in
the sulfonate-rich phase since both sulfonates exhibit
significant melting point depressions. The solubility data
are consistent with other literature studies showing that
fluorinating a compound reduces the pressures needed to
dissolve that compound in CO2. Further work is in progress to
polymerize related and fluorinated 1,4-dichlorobenzene
derivatives to determine the feasibility of thermally proces-
sing and curing the materials with supercritical CO2 as a
reaction medium.
3.1. Experimental
3.1.1. General synthetic experimental procedures
All manipulations of compounds and solvents were carried
out using standard Schlenk techniques. 1H and 13C NMR
measurements were performed using a Bruker AC 200 or
Bruker 400 MHz instrument. 1H and 13C NMR chemical shifts
1
are reported versus the deuterated solvent peak (solvent, H,
13C: CDCl3, d 7.18 ppm, d 77.0 ppm). The dichloromethane
(anhydrous), pentafluorophenol, 2,2,3,3,4,4,5,5-octafluoro-
pentanol, 2,5-dichlorobenzenesulfonyl chloride, nickel(II)
chloride, triphenylphosphine, zinc powder (10 mm), N-
methylpyrrolidinone (99.5%, anhydrous), and triethylamine
(anhydrous) were purchased from Aldrich Chemical Co. and
used as-received. Elemental analyses were performed at
Atlantic Microlab, Inc., Norcross, GA. Medical grade CO2 was
obtained from Roberts Oxygen and used as-received.
3. Concluding remarks
In this study we demonstrate the use of inexpensive and
commercially available 2,5-dichlorobenzenesulfonyl chloride

M.E. Wright et al. / Journal of Fluorine Chemistry 127 (2006) 330–336
335
3.1.2. Preparation of phenyl 2,5-dichlorobenzenesulfonate
(1a)
ꢀ15 cm3 working volume). The cell is first loaded with a
measured amount of sulfonate to within ꢄ0.002 g. To remove
entrapped air the cell is degassed with CO2 very slowly at
pressures less than 3 bar and then CO2 is transferred into the
cell gravimetrically to within ꢄ0.02 g using a high-pressure
bomb. The mixture in the cell is viewed with a borescope
(Olympus Corporation, model F100-024-000-55) placed
against a sapphire window secured at one end of the cell. A
stir bar is activated by a magnet located below the cell to mix
the contents of the cell. The solution temperature is measured to
within ꢄ0.1 8C (type K thermocouple calibrated against a
NIST certified thermometer) and is held constant to within
ꢄ0.3 8C. The system pressure is measured with a Heise
pressure gauge accurate to within ꢄ20 psi for data to
10,000 psig and with a pressure transducer (Viatran model
245) to within ꢄ50 psi for data higher than 10,000 psig. The
constant-composition mixture in the cell is compressed to a
single phase and the pressure is then slowly decreased until a
second phase appears. A dew point is obtained if a fine mist
appears in the cell and a solidification point is obtained if solid
particles appear in the cell. The pressure–temperature data
points of any given isopleth are averaged values from phase
transition measurements reproduced two-to-three times to
within ꢄ30 psi. Once an isopleth is obtained, more CO2 is
added to the cell to dilute the solution, and measurements are
repeated at this new concentration. The solution concentrations
of a given isopleth have an accumulated error of ꢀ1.0%.
Solution density data are also determined in the single-phase
region just prior to the phase transition using a linear
displacement technique [19,20] given in detail elsewhere
[21]. At a given pressure and temperature the volume of the cell
is determined by detecting the location of the internal piston
with an LVDT coil (Lucas Schaevitz Co., model 2000-HR) that
fits around a 1.43 cm high-pressure tube and tracks the
magnetic tip of a steel rod connected to the piston. Solution
densities are calculated knowing the amount of material in the
cell and the cell volume. The solution densities have an
accumulated uncertainty of ꢄ1.5% [21].
A flask was charged with 2,5-dichlorobenzenesulfonyl
chloride (10.0 g, 40.7 mmol), phenol (4.0 g, 44.8 mmol),
dichloromethane (100 mL), and then in one portion triethyla-
mine (5.9 mL) was added and the mixture was allowed to react
with stirring at ambient temperature for 2 h. The mixture was
diluted with ether (300 mL) and washed with water
(2 ꢃ 150 mL), and then brine (ꢀ50 mL). The organic layer
was separated and dried over magnesium sulfate, filtered, and
the solvents removed under reduced pressure. The crude
product was recrystallized from hexanes to afford 1a as
colorless crystals (10.8 g, 87%, mp 85–87 8C). 1H NMR
(200 MHz CDCl3): d 7.85 (dd, J = 2.0, 0.9 Hz, 1H), 7.47
(overlapping d, 2H), 7.30–7.20 (m, 3H), 7.11–7.04 (m, 2H); 13
C
NMR (50 MHz CDCl3): d 144.1, 129.8, 129.75, 128.2, 128.0,
126.9, 126.4, 124.8 (C30 & C50), 122.4, 116.7 (C20 & C60).
Anal. Calcd for C12H8Cl2O3S: C, 47.53; H, 2.64. Found: C,
47.79; H, 2.63.
3.1.3. Preparation of pentafluorophenyl 2,5-
dichlorobenzenesulfonate (1b)
A flask was charged with pentafluorophenol (8.24 g,
44.8 mmol), dichloromethane (100 mL), 2,5-dichlorobezene-
sulfonyl chloride (10.0 g, 40.8 mmol), and then in one portion
triethyl amine (5.9 mL) was added and the mixture was allowed
to react with stirring at ambient temperature for 2 h. The
mixture was diluted with ether (300 mL) and washed with
water (2 ꢃ 150 mL), and then brine (ꢀ50 mL). The organic
layer was separated and dried over magnesium sulfate, filtered,
and the solvents removed under reduced pressure. The crude
product was recrystallized from hexanes (ꢀ250 mL) to afford
1
1b as colorless crystals (11.0 g, 70%, mp 120–122 8C). H
NMR (200 MHz CDCl3): d 7.92 (dd, J = 2.0, 0.9 Hz, 1H), 7.56
(d, J = 2.0 Hz, 1H), 7.55 (d, J = 0.9 Hz, 1H). Anal. Calcd for
C12H3Cl2F5O3S: C, 36.67; H, 0.77; F, 24.17. Found: C, 36.77;
H, 0.76; F, 24.26.
3.1.4. Preparation of 2,2,3,3,4,4,5,5-octafluoropentyl 2,5-
dichlorobenzenesulfonate (1c)
3.1.6. Single-crystal molecular structure determinations
for phenyl 2,5-dichlorobenzenesulfonate (PDBS) and
A flask was charged with octafluoropentanol (10.4 g,
44.8 mmol), dichloromethane (100 mL), 2,5-dichlorobezene-
sulfonyl chloride (10.0 g, 40.8 mmol), and then in one portion
triethyl amine (5.9 mL) was added and the mixture was allowed
to react with stirring at ambient temperature for 2 h. Work up as
detailed above and then Kugelrhor distillation (0.2 mm, 150–
160 8C) afforded 1c as a light amber oil (11.0 g, 70%). 1H NMR
(200 MHz CDCl3): d 8.02 (dd, J = 2.0 Hz, 1H), 7.55 (d,
J = 2.0 Hz, 1H), 7.49 (s, 1H), 5.95 (tt, J = 5, 51 Hz, 1H), 4.57 (t,
J = 13 Hz, 2H). Anal. Calcd for C11H6Cl2F8O3S: C, 29.94; H,
1.36; F, 34.47. Found: C, 30.21; H, 1.38; F, 34.28.
pentafluorophenyl 2,5-dichlorobenzenesulfonate (FPDBS)
Single-crystals of PDBS were grown from cooling a hot
hexanes solution and FPDBS from a hot methanol solution.
Crystals were selected and mounted on glass fibers and epoxied
in place for data collection on a Siemens R3 4-circle
diffractometer using graphite monochromated Mo Ka radia-
tion. Data collection in u–2u mode yielded 2206 unique
reflections with Rint = 0.026 for PDBS and 2428 unique
reflections with Rint = 0.023 for FPDBS. The structures were
solved using SHELXTL-PC software [22] by direct methods.
Hydrogen atoms were included in the final refinements and
refined in the riding mode. Least squares refinement PDBS
using 1725 reflections (Fo > 4s), 163 parameters, resulted in
R1 = 0.0393, GOF = 1.06 and for FPDBS, 1747 (Fo > 4s)
reflections gave R1 = 0.0695 and a GOF = 1.67. The details of
the data collection and refinement are summarized in Table 1.
3.1.5. Phase behavior measurements
Described elsewhere are the apparatus and techniques used
to obtain sulfonate-CO2 phase behavior data [5,18]. The main
component of the experimental apparatus is a high-pressure,
variable-volume cell (Nitronic 50, 7.0 cm o.d. ꢃ 1.5 cm i.d.,

336
M.E. Wright et al. / Journal of Fluorine Chemistry 127 (2006) 330–336
[10] J.R. Fried, N. Hu, Polymer 44 (2003) 4363–4377.
Acknowledgments
[11] B. Baradie, M.S. Shoichet, Z. Shen, M.A. McHugh, L. Hong, Y. Wang,
J.K. Johnson, E.J. Beckman, R.M. Enick, Macromolecules 37 (2004)
7799–7807.
MEW acknowledges support of this work by the Office of
Naval Research through the ILIR program and CEG expresses
his gratitude for support through the Naval Research Enterprise
Intern Program.
[12] Z. Shen, M.A. McHugh, K.M. Lott, M.E. Wright, Fluid Phase Equilib. 216
(2004) 1–12.
[13] Z. Shen, K.M. Lott, M.E. Wright, M.A. McHugh, Fluid Phase Equilib. 238
(2005) 210–219.
[14] Phenyl 2,5-dichlorobenzenesulfonate [CAS 41480-03-9] was first
reported by: R.V. Vizgert, E.K. Savchuk, Zhur. Obshchei Khimii 26
(1956) 2268–2273. Lit. mp of 91–91 8C.
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