Ionic Liquids

Tomohiro Yamamoto
2012/11/5

Solvents - classification

H2O

Organic solvents

Ionic Liquids

Hydrogen bondVan der Waals
interaction

Coulomb
interaction

Contents
1. Basic
2. Application
2-1. Organic Reaction
2-2. Bioscience
2-3. Supported Ionic Liquid Phase (SILP)
3. Summary

1. Basic

Definition• Ionic Liquids are ionic compounds(salts) which
are liquid below 100 ℃. More commonly,
Ionic Liquids have melting points below room
temperature.
cationFree
Customization!
anion

1. BasicHistory
1914 – [EtNH3][NO3] (m.p. 12oC) was first described.
1970s~1980s – imidazolium and pyridinium cation, halide anion
1992 – [BF4]-, [PF6]2000s – [NTf2]-

1. Basic

Designers solvent – ionic liquids ①

1. Viscosity
2. Surface tension
3. Melting point

1. Oxygen balance
2. Density
3. High energy
content ion

Stability

Functionality

about 1000 ILs are described in the literature,
300 are commercially available.

1. Basic

Designers solvent – ionic liquids ②

1. Basic

Characteristics ①

Fluorous ILs are immisciblewith both organic and aqueous solvents.

1. Basic

Characteristics ②

m.p.

cationandanion size

highsmalllowlarge

1. Basic

Melting point ①

1. Basic

Melting point ②

1. Basic

DSC (Differential Scanning Calorimetry) ①
DSC is a thermoanalytical technique in which the difference in the amount ofheat required to increase the temperature of a sample and reference ismeasured as a function of temperature.
Using this technique it is possible to observe fusion and crystallization
events as well as glass transition temperatures Tg

Fig.1 DSC

Fig.2

Fig.3

Fig.4

1. Basic

DSC (Differential Scanning Calorimetry) ②
Supercoolingliquidliquidglassm.p.

Phase transition is hard to happen.

Flexibility of the constituent ions+
Conformational diversity

1. Basic.

Preparation and Purification<Purification>
Negligible volatility

distillation

Low melting pointrecrystallization at low temperature1. Basic

Catalog (Aldrich)Database ①
http://ilthermo.boulder.nist.gov/ILThermo/pureils.uix.do?event=NewSearchDatabase ②
http://ilthermo.boulder.nist.gov/ILThermo/pureils.uix.do?event=NewSearch2. Application
Today’s Topics

2-1.

Organic Reaction (TEMPO oxidation) ①

2-1.

Organic Reaction (TEMPO oxidation) ②

R. Gree, et al. Org. Lett. 2002, 4, 9.

2-1.

Organic Reaction (TEMPO oxidation) ③
O2
Et2O phase[C4mim][PF6] phase2-1.

Organic Reaction (other reactions)Figure 1. Pauson-Khand reaction

Figure 4. Olefin Metathesis
Figure 2. Heck Arylation

Figure 3. Tsuji-Trost reaction

and so on.

2-2.

Bioscience (Biorefinery) ①

1st step : Extraction and dissolution of polysaccharides from biomass

2nd step : Hydrolysis of polysaccharides into mono-, di-, or oligo-saccharide

3rd step : Conversion of chemical energy, involving the resulting sugars, intoelectric energy

2-2.

Bioscience (Biorefinery) ②

Problem : Cellulose is insoluble in water andcommon organic reagents.

2-2.

Bioscience (Biorefinery) ③

NN

n-1

[Cnmim]+(Cn-methylimidazolium)

The melting point of [C4mim]Cl is 70oC.
Extra energy is needed to operate with IL based on [C4mim]ClR. D. Rogers, et al. J. Am. Chem. Soc. 2002, 124, 4974.

2-2.

Bioscience (Biorefinery) ④

Chloride anion : 70 oC
Phosphonate anion : r.t.
@50 oC

H. Ohno, et al. Green Chem. 2010, 12, 1274.

2-2.

Bioscience (Biorefinery) ⑤R. D. Rogers, et al. J. Am. Chem. Soc. 2002, 124, 4974.

2-2.

Bioscience (Biorefinery) ⑥

H. Ohno, et al. Green Chem. 2010, 12, 1274.

2-2.

Bioscience (Biorefinery) ⑦

B. Scrosati, et al. Nature. Mater. 2009, 7, 621.

2-3.

Supported Ionic Liquid Phase (SILP) ①

Homogeneous
Catalyst

v.s.

Heterogeneous
Catalyst

difficult / expensive
poor
excellent

Recovery
Thermal Stability
Selectivity

easy / cheap
goodpoor

2-3.

Supported Ionic Liquid Phase (SILP) ②- SILP catalysis is a concept which combines the advantages ofionic liquids with those of heterogeneous support materials.

C. P. Mehnert, et al. J. Am. Chem. Soc. 2002, 124, 12932.

2-3.

Supported Ionic Liquid Phase (SILP) ③

M. Haumann, A. Riisager, Chem. Rev. 2008, 108, 1474.

2-3.

Supported Ionic Liquid Phase (SILP) ④
 SILP materials are prepared bydispersing a solution of the catalyst
complex in an ionic liquid as a thin filmon porous solid materials.
 This layer serves as the reaction phasein which the homogeneous catalist isdissolved.

C. P. Mehnert, et al. Chem. Eur. J. 2005, 11, 50.

2-3.

Supported Ionic Liquid Phase (SILP) ⑤～ For Hydroformylation ～[Industrial process] Ruhrchemie-Rhone-Poulenc process- Aqueous-organic biphasic catalist

cat.

Problem : Phosphite ligands decompose by hydrolysis in water.
C. W. Kohlpaintner, et al. Appl. Catal. A. 2001, 221, 219.

2-3.

Supported Ionic Liquid Phase (SILP) ⑥<Selectivity>
Mixed C4 Feedstocks

25.6%

trans:9.1%
cis:7.0%

43.1%

14.9%

0.3%

?
M. Haumann, P. Wassersheid, et al. Angew. Chem. Int. Ed. 2011, 50, 4492.

2-3.

Supported Ionic Liquid Phase (SILP) ⑦

Fig. Preparation of SILP catalyst

M. Haumann, P. Wassersheid, et al. Angew. Chem. Int. Ed. 2011, 50, 4492.

2-3.

Supported Ionic Liquid Phase (SILP) ⑧
80 oC
selectivity

100 oC

80 oC
100 oC
conversion

Diphosphite ligand 2 decomposition leads tothe formation of phosphoric acid.
M. Haumann, P. Wassersheid, et al. Angew. Chem. Int. Ed. 2011, 50, 4492.

2-3.

Supported Ionic Liquid Phase (SILP) ⑨
selectivity

conversion
Additive 3 works as acid scavenger that
does not interact or react with the active
catalytic species.

TON : 350000 !!

M. Haumann, P. Wassersheid, et al. Angew. Chem. Int. Ed. 2011, 50, 4492.

3. Summary• Ionic liquids are not simple fruids.
- the tunability of the cation and anion independently
offers almost unlimited access to targeted
combinations of physical and chemical properties.
• The scientific and technological importance of ionicliquids today spans a wide range of applications.

References
T. Welton, Chem. Rev. 1999, 99, 2071.
V. I. Parvulescu, C. Hardacre, Chem. Rev. 2007, 107, 2615.
M. Haumann, A. Riisager, Chem. Rev. 2008, 108, 1474.
J. P. Hallett, T. Welton, Chem. Rev. 2011, 111, 3508.
現代化学.
現代化学 2007, 3.
現代化学.
現代化学 2010, 10
Sigma-Aldrich, Aldrich ChemFiles. 2005, Vol.5, No.6.
B. Scrosati, et al. Nature. Mater. 2009, 7, 621.