SWITCHABLE SOLVENTS AND SURFACTANTS · SWITCHABLE SOLVENTS AND SURFACTANTS Philip G. Jessop...
Transcript of SWITCHABLE SOLVENTS AND SURFACTANTS · SWITCHABLE SOLVENTS AND SURFACTANTS Philip G. Jessop...
SWITCHABLE SOLVENTS ANDSURFACTANTS
Philip G. JessopQueen’s UniversityKingston, Ontario
Charles A. Eckert and Charles L. LiottaGeorgia Institute of Technology
Atlanta, Georgia
SWITCHABLE SOLVENTS
"Switchable" = able to switch on and off, or switch between one property and another,when a trigger is applied.
A solvent could switch between:
• high polarity / low polarity• volatile / nonvolatile• protic / aprotic• fluorophobic / fluorophilic
OUTLINE
POLARITY SWITCHABLE SOLVENTS
• elevated pressure• atmospheric pressure
OTHER KINDS OF SWITCHABLE SOLVENTS
SWITCHABLE SURFACTANTS
nonpolarsolvent highpolaritysolvent
lowpolaritysolvent
Makita et al., Refrigeration Tokyo Nippon Reito Kyokui (1976) 52, 543.Rhodes et al., J. Phys. Chem. (1995) 99, 9903.
Pressure, bar
10°C
100°C
7
9
4
0 40 120
8
6
2
80 160
5
3
1
50°C
Diel
ectri
c Co
nsta
nt
POLARITY SWITCHING OF A SUPERCRITICAL FLUID (CHF3)
POLARITY SWITCHING OF A SUPERCRITICAL FLUID
Works for the following SCFs:
• low Tc, high price: CHF3, CH2F2
• high Tc, low price: MeOH, NH3, H2O
Advantages Disadvantages
Continuous variability Limited polarity range
Non-reactive solvents High pressure
Stability High price for some,high T for others
addCO2
Green Chem. (2003), 5, 123-128
1 barCO2
high PCO2
POLARITY SWITCHING BY SOLVENT EXPANSION
releaseCO2
EXPANSION OF LIQUIDS BY CO2
CO2-expanded NEt3 (Jessop, 1996)
vo
lum
etr
ic e
xp
an
sio
n,
%
1000
800
600
400
200
0
P, bar
0 20 40 8060
dioxaneethyl acetate
acetonitrile
Volumetric expansion of aprotic solvents by CO2 at 40˚C (Kordikowski, 1995)
EFFECT OF EXPANSION ON π∗
EtOC4F9
[bmim]BF4
MeOHacetone
[bmim]PF6
Wyatt, J. Supercrit. Fluids 2005, 36, 16. Fredlake, PhysChemChemPhys. 2004, 6, 3280. Kho, Fluid Phase Eq. 2003, 206, 179.
incr
easin
g po
larit
y
POLARITY SWITCHING BY EXPANSION
Advantages Disadvantages
Continuous variability Pressure
Non-reactive solvents Acidity
Stability
A ROOM PRESSURE SWITCHABLE SOLVENT
N
N CO2
N2 N
N+
H
-OC(O)OR+ ROH
• Immediate heat release and viscosity rise upon bubbling CO2
• Ions confirmed by MS, NMR, IR• Reversible at room temperature but faster at 70 ˚C• This reaction first observed by Linehan.
Jessop, patent application Jessop, Nature (2005) 436, 1102
DBU
CO2
N2 or Ar
DOES THE POLARITY CHANGE?
N
N CO2
N2 N
N+
H
-OC(O)OR+ ROH
535.2CH2Cl2
538DBU + hexanol
538CHCl3
541DMF
542Propanoic acid
545DBU + hexanol
548[bmim]PF6
550Methanol
504.4Ether
λmax (Nile Red)nm
Solvent
Refs for other solvents:
Muldoon, JCS Perkin 2 (2001) 433Deye, Anal Chem (1990) 615Carmichael, J Phys Org Chem (2000) 591
incr
easin
g po
larit
y
POLARITIES
N
N CO2
N2 N
N+
H
-OC(O)OR+ ROH
λmaxnm
ionic form
non-ionic form
incr
easin
g po
larit
y
MELTING POINTS
N
N CO2
N2 N
N+
H
-OC(O)OR+ ROH
OTHER BASES AND ALCOHOLS
N
N CO2
N2 N
N+
H
-OC(O)OR+ ROH
Base ROH Result
DBU 2˚ ROH Low conversion
DBU 3˚ ROH No conversion
DBU H2O Solid
N
N
PhN H2O
N
NPh
N+
H
-OC(O)OH
CH3CH2CH2OH No conversion
NEt3 CH3CH2CH2OH No conversion
N
DOES THE POLARITY CHANGE AFFECT SOLUBILITY?
N
N CO2
N2 N
N+
H
-OC(O)OR+ ROH
DecaneROHDBU
N2
Decane
CO2
ionic liquid
CO2
N2 or Ar
R = Hexyl
DOES THE POLARITY CHANGE AFFECT SOLUBILITY?
N
N CO2
N2 N
N+
H
-OC(O)OR+ ROH
InsolInsolGlucose
SolSolToluene
InsolSolPolystyrene
SolInsol[PhCH2NMe3]Cl
InsolInsol[NMe4][O3SC6H4Me]
InsolSolIbuprofen
InsolSolDecane
Ionic formNon-ionic formSolute
For solids: 50 mg of solute in 2.22 mL of solventFor liquids: 0.5 mL of liquid in 2.22 mL of solvent
R = Propyl
APPLICATION OF POLARITY SWITCHING
CO2
1.0 mL styrene4.5 mL DBU/PrOH45 mg initiator
75 ˚C
6 h
filter or centrifuge
+
Mn = 412,000PDI = 1.57
No pressure required
CO2-TRIGGERED SWITCHABLE SOLVENTS
Advantages Disadvantages
Switches polarity Reactivity
Price
Benign triggers Polarity difference could be wider
nonpolarsolvent
Polarnonvolatilesolvent
volatilesolvent
RETRO-CHELOTROPIC REACTIONS
S
O
O
+ SO2
S + SO
+ COO
C
O
O
+ CO2
O
Melting Point of Sulfolene
CHOICE OF SULFOLENE
+ SO2 S
O
O
+ SO2 S
O
O
+ SO2 S
O
O
+ SO2 S
O
O
64-65 ˚C
63-64 ˚C
134-136 ˚C
~ -12 ˚C
(Pvap = 7 mmHg @ 85°C)
42.646.7ε189.0189.0ET(30) (kJ/mol)0.871π*0.460.76β0.00.0α
Piperylene SulfoleneDMSOProperty
S
O
OS
O
SOLVENT PROPERTIES
2.3 x 10-41.0 x 10-4KSCN
> 1.8 x 10-1> 1.8 x 10-1KTA
> 1.8 x 10-1> 1.8 x 10-1NaPDTC
1.5 x 10-55.5 x 10-4KCN
1.9 x 10-53.4 x 10-4KOAc
3.5 x 10-52.2 x 10-3CsOAc
5.8 x 10-46.8 x 10-3CsN3
2nd Order RateConstant in moist PS(L/mol sec)
2nd Order Rate Constantin DMSO (L/mol sec)
Nucleophile
KTA
NaPDTC
Cl
M+Nu-
Nu
+ + M+Cl-
40 °C
REACTIONS IN SWITCHABLE SULFOLENE
N
S S Na
O
CH3SK
m.p. = –12 °C b.p. = 42 °C -10 °C
+ SO2S
O
O
10
100
1000
10000
75 100 125 150
T (0C)
t 1/2
(m
in)
Butadiene sulfone
Piperylene sulfone
Isoprene sulfone
Drake et al. JACS, 1946, 68, 2521.
SWITCHING THE SULFOLENE SOLVENT
!
Cl
KTA+
PS
S
O
Cl S
40 °C
KTA
O
+ SO2
SWITCHING THE SULFOLENE SOLVENT
SO2-TRIGGERED SWITCHABLE SOLVENTS
Advantages Disadvantages
Switches volatility Some loss of diene
No pressure required Irritating odor
Less reactive than DBU
water
A SWITCHABLE SURFACTANT
oil
A SWITCHABLE SURFACTANT
oil/wateremulsion
oil
oil
oil
water
A SWITCHABLE SURFACTANT
oil/wateremulsion
oil
oil
water
A SWITCHABLE SURFACTANT?
patent application (2005)Science (2006)
hydrophobichydrophilic
hydrophobic hydrophobic
A SWITCHABLE SURFACTANT?
patent application (2005)Science (2006)
hydrophobichydrophilic
hydrophobic hydrophobicLiterature examples:
ferrocene head-group Sakai et al, 1990’s
Azobenzene head-group Sakai et al. 1999Viologen head-group Anton et al. 1992
A SWITCHABLE SURFACTANT?
C16H33
N NMe2
Me
CO2, H2OC16H33
NH
NMe2
Me
+
-O2COH
C16H33NH2 +
-2MeOH60 ˚C10-20 minno solvent
Me C NMe2
OMe
OMe
N2
patent application (2005)Science (2006)
hydrophobichydrophilic
MICELLE FORMATION
C12H25
NH
NMe2+
-O2COH
C12H25
NH
NMe2+
-Cl
C16H33
NH
NMe2+
-Cl
CMC
2.2 mM
0.5 mM
0.5 mM
[C14H29Pyr]Br 2.7 mM
THE SURFACTANTS SWITCH ON AND OFF
C16 amidine (20 mM) in DMSO at room temperature
Under CO2 Under Ar
EMULSION TEST WITH HEXADECANE
Hexadecane (4 ml), H2O (2 ml),C16 amidine 90 mg,shaken 10 min After 5 min
After 30 min
After 24 h
After Ar & ∆
Under CO2 Under Ar
EMULSION TEST WITH CRUDE OIL
After 5 min
After 30 min
After 60 min
After 15.5 h
No amidineCrude oil (4 ml),H2O (2 ml), C16amidine 90 mg,shaken 10 min
MICROSUSPENSION POLYMERIZATION
Ph
Ph
1. initiator
H2O/styrene emulsion
4 % [C12H+][HCO3]
65-70 ˚C under CO2
2. hydroquinone quench
Latex
Ar, !
Ph
ppt
n n
Mn = 276,000 g/mol PDI = 2.14 number-weighted mean diameter = 2.79 µm
CONCLUSIONS
Switchable solvent Advantages
Supercritical fluid Inert
Expanded liquids Inert
Atmospheric pressure systems No pressure
Disadvantages
Pressure, price
Pressure, acidity
Reactivity
Solvents don’t have to be unchangeable.
We can demand more flexibility from them.
Funding
Queen’s UniversityCFI/OIT (Canada)NSERC (Canada)DOE (USA)Canada Research Chairs Program
Collaborators
Dr. M. Cunningham (Queen’s)Dr. D. Darensbourg (Texas A&M)Dr. A. Daugulis (Queen’s) Dr. B. Davis (Queen’s)Dr. C. A. Eckert (Georgia Tech)Dr. C. L. Liotta (Georgia Tech)Dr. A. Rheingold (Delaware)
ACKNOWLEDGEMENTS
Grads/PDFs Contributing to This Work
Ms. Sindy Liu (Queen’s)Mr. Li Xiaowang (Queen’s)Mr. Lam Phan (Queen’s)Ms. Dolores Wynne (UCDavis)
Mr. C. Thomas (Georgia Tech)Mr. J. Hallett (Georgia Tech)Ms. E. John (Georgia Tech)Dr. Daniele Vinci (Georgia Tech)
Liotta Eckert