Piperylene sulfone: A labile and recyclable DMSO substitute

Article abstract of DOI:10.1039/b616806j

The properties and uses of piperylene sulfone as a new, recyclable dipolar, aprotic solvent for conducting organic reactions are presented. The Royal Society of Chemistry.

Full text of DOI:10.1039/b616806j

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Piperylene sulfone: a labile and recyclable DMSO substitute
ac
D. Vinci, M. Donaldson, J. P. Hallett, E. A. John, P. Pollet, C. A. Thomas, J. D. Grilly,
bc
bc
ac
ac
ac
bc
d
abc
P. G. Jessop, C. L. Liotta* and C. A. Eckert*
abc
Received (in Cambridge, UK) 16th November 2006, Accepted 10th January 2007
First published as an Advance Article on the web 30th January 2007
DOI: 10.1039/b616806j
The properties and uses of piperylene sulfone as a new,
recyclable dipolar, aprotic solvent for conducting organic
reactions are presented.
Solvents are vital to many industrial reaction processes. They
affect reaction rates, chemical equilibria, and the efficiency of heat
and mass transfer. The literature is filled with reports of the
1
development of novel solvents. These include ionic liquids,
Fig. 1 Piperylene sulfone reversible reaction to trans-1,3-pentadiene and
sulfur dioxide.
2
supercritical fluids, gas-expanded liquids, and perfluorinated
3
4
solvents. The choice of the right solvent is critical not only for a
decomposes back to gaseous trans-1,3-pentadiene (bp 42 uC) and
1
0
successful chemical transformation but also for the subsequent
5
separation and purification processes. The reactions of organic
sulfur dioxide (bp 210 uC) (Fig. 1).
Piperylene sulfone is a close mimic of DMSO in terms of its
substrates with inorganic salts are particularly challenging because
they traditionally need either a dipolar, aprotic solvent or a
biphasic mixture of solvents combined with a phase-transfer
solvent properties. Properties of solvents are usually characterized
11
by the Kamlet–Taft parameters (p*, a and b) the E (30)
T
1
2
parameter developed by Reichardt et al., and the dielectric
13
constant (e). Each of these parameters has now been measured
6
catalyst. The latter approach is limited because the phase transfer
2c,3e
catalysts are difficult to separate and recycle.
The former
for piperylene sulfone and compared to the corresponding values
for DMSO. These values, along with other pertinent physical
constants (bp, mp, dipole moment) are summarized in Table 1.
The only significant difference between the two solvents is the
b-value; which indicates that DMSO is better than piperylene
sulfone at accepting hydrogen bonds.
option, dipolar, aprotic solvents, is expensive (in terms of money
and energy) because such solvents are very difficult to remove by
distillation. Dimethyl sulfoxide (DMSO), dimethylformamide
(DMF), and hexamethylphosphoramide (HMPA), for example,
have boiling points of 189, 153 and 235 uC, respectively. In
addition, it is rarely practical to recycle and reuse such solvents.
Indeed, the pharmaceutical industry has emphasized the need for a
To demonstrate that piperylene sulfone can serve as a solvent
for chemical processes, the new solvent was tested as a medium for
anionic nucleophilic substitution reactions. The second-order rate
constants for the reaction of benzyl chloride with a variety of
anionic nucleophiles were studied in both piperylene sulfone and
7
dipolar, aprotic replacement for DMSO.
We now report a separable and recyclable dipolar, aprotic
8
solvent, piperylene sulfone (PS), which combines the excellent
1
4
reaction medium properties of dipolar, aprotic solvents with the
DMSO at 40 uC (Table 2). It was discovered early in this
research that traces of water added to the piperylene sulfone
enhanced the rate of reaction. Indeed, no reaction was observed
with potassium cyanide in dry piperylene sulfone (see Table 2).
Only in the presence of trace amounts of water (0.1 wt%) did the
reaction take place. As a consequence, studies were conducted in
dry DMSO, DMSO containing 3 wt% water, dry piperylene
sulfone, and piperylene sulfone containing from 0.1 to 10 wt%
‘‘volatility’’ of low boiling solvents necessary for facile isolation
and purification of products. While piperylene sulfone is not
volatile itself, it is readily converted (or ‘‘switched’’) into volatile
species. These volatile species can be collected elsewhere and
recombined back into piperylene sulfone for re-use. It is therefore
3
,9
an example of a switchable solvent. We also report the rates of
anionic nucleophilic substitution reactions in both piperylene
sulfone and DMSO.
1
5
water. Since most of the nucleophilic salts were only partially
soluble in all the solvent systems studied the reactions were
Piperylene sulfone is a liquid at room temperature with a
melting point of 212 uC. It is easily synthesized by a reaction of
trans-1,3-pentadiene (trans-piperylene) and sulfur dioxide. At
temperatures greater than 100 uC it cleanly and efficiently
Table 1 Comparison of solvent properties for DMSO and PS at 25 uC
Properties
DMSO
PS
a
School of Chemistry and Biochemistry, Georgia Institute of
Boiling point/uC
Melting point/uC
Dipole moment (D)
51 (7 Torr)
16–19
4.27
0
0.76
1.00
189.0
46.7
85 (7 Torr)
212
5.32
0
0.46
0.87
189.0
42.6
Technology, Atlanta, GA, 30332, USA. E-mail: cae@gatech.edu;
Fax: 4048949085; Tel: 4048947070
School of Chemical and Biomolecular Engineering, Georgia Institute of
b
a
Technology, Atlanta, Georgia, 30332, USA
Specialty Separations Center, Georgia Institute of Technology, Atlanta,
b
p*
c
Georgia 30332
Department of Chemistry, Queen’s University, Kingston, Ontario,
Canada
21
E
T
(30)/kJ mol
d
e
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Table 2 Second-order rate constants for the nucleophilic displace-
ment in DMSO, DMSO with 3% water, PS and PS with 1% water at
and reversible reaction between trans-piperylene and sulfur
dioxide, product isolation and solvent recycle are easily accom-
plished. Finally we recognize that PS cannot be substituted for
DMSO in all reaction classes. We are currently investigating the
breath of reactions which can be conducted in PS.
40 uC
Notes and references
4
21 21
s
Second-order rate constant, k 6 10 /l mol
1 (a) R. D. Rogers and K. R. Seddon, Ionic Liquids as Green Solvents:
Progress and Prospects, ACS Symp. Ser., American Chemical Society,
Washington, DC, 2003, vol. 856, p. 599; (b) P. Wasserscheid and
T. Welton, Ionic Liquids in Synthesis, WILEY-VCH, Weinheim, 2003.
2 (a) G. Brunner, Supercritical Fluids as Solvents and Reaction Media,
Elsevier B. V., Amsterdam, 2004, p. 641; (b) P. G. Jessop and W. Leitner,
Chemical Synthesis Using Supercritical Fluids, WILEY-VCH,
Weinheim, 1999, p. 480; (c) A. K. Dillow, S. L. J. Yun, D. Suleiman,
D. L. Boatright, C. L. Liotta and C. A. Eckert, Ind. Eng. Chem. Res.,
DMSO
(3% H
a
PS (1% H
NuM
DMSO
2
O)
PS
2
O)
b
PTA
SPTC
.1800
.1800
1.4 ¡ 0.1
.1800
.1800
1.7 ¡ 0.1
.1800
.1800
2.1 ¡ 0.1
.1800
.1800
2.3 ¡ 0.2
c
KSCN
KOAc
KCN
3.4 ¡ 0.1 11.0 ¡ 0.1 0.013 ¡ 0.004 0.19 ¡ 0.1
d
5.8 ¡ 0.1
69 ¡ 0.8 16.7 ¡ 5
CsOAc 22.7 ¡ 0.6 16.4 ¡ 0.9
17 ¡ 0.1
—
2.4 ¡ 0.9
0.35 ¡ 0.04
0.15 ¡ 0.01
5.8 ¡ 0.9
0.35 ¡ 0.06
1996, 35, 1801; (d) J. F. Brennecke, D. L. Tomasko and C. A. Eckert,
J. Phys. Chem., 1990, 94, 7692.
CsN
3
3
(a) J. P. Hallett, C. L. Kitchens, R. Hernandez, C. L. Liotta and
C. Eckert, Acc. Chem. Res., 2006, in press; (b) C. A. Eckert, C. L. Liotta,
D. Bush, J. S. Brown and J. P. Hallett, J. Phys. Chem. B, 2004, 108,
a
Only the rate constants for piperylene sulfone containing 1 wt%
water are presented since the rates of reaction changed by only a
factor of two for the entire water range studied. Potassium
b
1
8108; (c) J. M. Broering, E. M. Hill, J. P. Hallett, C. L. Liotta,
C. A. Eckert and A. S. Bommarius, Angew. Chem., Int. Ed., 2006, 118,
786; (d) J. Lu, M. J. Lazzaroni, J. P. Hallett, A. S. Bommarius,
c
d
thioacetate. Sodium pyrrolidinedithiocarbamate. No reaction.
4
C. L. Liotta and C. A. Eckert, Ind. Eng. Chem. Res., 2004, 43, 1586; (e)
X. Xie, J. S. Brown, P. J. Joseph, C. L. Liotta and C. A. Eckert, Chem.
Commun., 2002, 1156–1157.
(a) C. D. Ablan, J. P. Hallett, K. N. West, R. S. Johnes, C. A. Eckert,
C. L. Liotta and P. G. Jessop, Chem. Commun., 2003, 2972; (b)
Y. W. Kho, D. C. Conrad, R. A. Shick and B. L. Knutson, Ind. Eng.
Chem. Res., 2003, 42, 6511; (c) M. S. Yu, D. P. Curran and
T. Nagashima, Org. Lett., 2005, 7, 3677; (d) K. N. West, J. P. Hallett,
R. S. Johnes, D. Bush, C. L. Liotta and C. A. Eckert, Ind. Eng. Chem.
Res., 2004, 43, 4827.
C. Reichardt, Solvents and Solvent Effects in Organic Chemistry,
WILEY-VCH, Weinheim, 3rd edn, 2003, p. 653.
C. M. Starks, C. L. Liotta and M. Halpern, Phase-Transfer Catalysis:
Fundamentals, Applications, and Industrial Perspectives, Chapman &
Hall, New York, 1994, p. 688.
heterogeneous and stirring was required. In general, the reactions
are quantitative and the rates are slower in the piperylene sulfone
solvent systems compared with the DMSO counterparts. This
latter observation could be attributed to the difference in hydrogen
bond accepting ability, as indicated by the b-values of the two
solvents. It is conjectured that DMSO solvates the cation more
strongly than the PS facilitating greater ion-pair separation
between the cation and the anion thus enhancing the nucleophi-
4
5
6
16
licity of the anion.
A complete process (Fig. 2), taking advantage of PS’s switch-
ability, would include a feed (reactants), the reaction to products
(
where PS is serving as an inert solvent), a decomposition stage
where PS is converted into gaseous trans-1,3-pentadiene and SO
and products are removed), and a reformation stage (where the
7
8
P. J. Dunn, in 10th Annual Green Chemistry & Engineering Conference,
Washington, DC, 2006.
IUPAC name: 2-methyl-2,5-dihydrothiophene 1,1-dioxide. For NMR
references, see: (a) S. Yamada, H. Ohsawa, T. Suzuki and H. Takayama,
J. Org. Chem., 1986, 51, 4934–4940; (b) T. Chou, H.-H. Tso and
L.-J. Chang, J. Chem. Soc., Perkin Trans. 1, 1985, 515–520.
(
2
17
gases are reconverted back into PS).
In conclusion, piperylene sulfone has been shown to be a good
medium for reactions of anionic nucleophiles with organic
electrophiles. It is a dipolar, aprotic solvent which mimics the
properties of DMSO. However, unlike DMSO, because of a facile
9 P. G. Jessop, D. J. Heldebrant, L. Xiaowang, C. A. Eckert and
C. L. Liotta, Nature, 2005, 436, 1102.
10 In a thermogravimetric analysis (TGA) of piperylene sulfone the sample
21
was heated at a rate of 5 uC min up to 120 uC and held constant at
120 uC for 30 min. No residual mass was left after 2500 s. The TGA also
showed that, while piperylene sulfone is relatively stable up to 80 uC, its
decomposition rate increases dramatically at 100 uC.
1
1 (a) M. J. Kamlet, J. L. Abboud and R. W. Taft, J. Am. Chem. Soc.,
977, 99, 6027; (b) R. W. Taft and M. J. Kamlet, J. Am. Chem. Soc.,
976, 98, 2886.
2 C. Reichardt, Chem. Rev., 1994, 94, 2319.
3 Y. Marcus, Chem. Soc. Rev., 1993, 22, 409.
4 Standard procedure for the kinetics of reaction of benzyl chloride with
1
1
1
1
1
anionic nucleophiles: A reaction vessel was charged with 0.3 mmol of the
anionic nucleophile salt and 1 mL of solvent. The mixture was stirred at
40 uC for 30 min and then benzyl chloride (0.15 mmol) was added.
Samples were taken at regular intervals of 10 min over 1 h period and
quenched by dissolution in toluene. The concentrations of reactants and
products were quantified by GC/FID analysis. The errors on the rate
constant values were calculated as the standard deviation from the
average value of multiple repetitions.
1
5 It is conjectured that, as in the case of solid–liquid phase transfer
catalysis, small quantities of water enhance the rate of reactions in
heterogeneous systems by facilitating a more rapid dissolution of the
salts in the solvent phase (ref. 6, pp. 113–119).
Fig. 2 The process can be divided in four stages. Only one arrow comes
in, the feed (reactants), and one arrow comes out, the products.
16 Ref. 6, p. 85.
1
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1
7 Reaction–decomposition–recovery–reformation procedure: KSCN
1.5 mmol) and PS (5 mL) were placed in a vessel (40 uC) connected
to another vessel containing liquid SO (230 uC). After 30 min of
benzyl thiocyanate in 96% yield (this preparative process was also
repeated with the nucleophilic salts potassium thioacetate and sodium
pyrrolidinedithiocarbamate to afford 97 and 99% isolated yields of
(
2
stirring benzyl chloride (0.75 mmol) was added to the first vessel. When
2
products, respectively). The excess SO was degassed from the second
all BnCl had reacted, the temperature of the first vessel was raised to
vessel and aqueous/organic back extraction work-up afforded pure
PS in 87% yield. This percentage recovery is due to minor losses because
of the small scale of the laboratory procedure – simple surface adhesion
or adsorption accounts for most of these losses. Were the process scaled
up it is anticipated that the percent recovery would be nearly
quantitative.
1
10 uC to begin the decomposition process. PS decomposes into trans-
piperylene and SO which condense into the second vessel; this mixture
2
was stirred for 48 h. The residue of the first vessel was washed with
water and then extracted with diethyl ether. Filtration over a short pad
of silica gel and subsequent evaporation of the solvent, afforded pure
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Chem. Commun., 2007, 1427–1429 | 1429