Chất lỏng ion (ionic liquids), tính chất, tổng hợp và ứng dụng.

Ionic Liquids in
Green Chemistry
Huynh Thanh Dien
Nguyen Quoc Tuan
Ngo Nguyen Phuong Duy
Prepared by:
An overview about Ils in
Green Chemistry
Synthesis methods of ILs
Applications of ILs
Content
3
Content
An overview about
Ionic Liquids (ILs) in
Green Chemistry
Prepared: Huynh Thanh Dien

What are Ionic liquids (ILs)?

Why consider of ILs?

The characteristic properties of ionic
liquids
Ionic Liquids in Green Chemistry

1888 Gabriel and Weiner found ethanolammonium nitrate (m.p. 52–55 ◦C)

1914 The “first” RTIL ethylammonium nitrate [EtNH3][NO3] with melting
point12 ◦C


1948 Development of IL with chloroaluminate ions by Hurley and Wier at
the Rice Institute in Texas

1982 reported by Wilkes , A new class of RTILs that consist of
dialkylimidazolium chloroaluminate

1992 Development of air- and water-stable imidazolium based ILs by
Wilkes et al.
History
Development
What are ionic liquids?
Definition:
Quite simply, they are liquids that are composed
entirely of ions.
In the broad sense, this term includes all the molten
salts, for instance, sodium chloride at temperatures
higher than 800 oC.
Ionic liquids are salts that are liquid at low
temperature (<100 oC) which represent a new class
of solvents with nonmolecular, ionic character.
What are ionic liquids?
What are ionic liquids?
Traditional salts like
sodium chloride are able to
efficiently pack to form a
crystal lattice
With ionic liquids, the cations
are asymmetrically substituted
with different length groups to

prevent the packing of the
cations/anions into a crystal
lattice
Room temperature Ionic liquids

Room temperature ionic liquids (RTIL) are salts
which are already liquid below room
temperature

Variations in cations and anions can produce
literally millions of ionic liquids, including
chiral, fluorinated, and antibacterial IL.

Large number of possibilities allows for fine-
tuning the ionic liquid properties for specific
applications
The driving forces
The problems in the chemical industry with the
volatile organic compounds (VOCs) :
•
toxic and/or hazardous
•
serious environmental issues, such as
atmospheric emissions and
contamination of aqueous effluents
The driving force in the quest for novel reaction media:
•
greener processes
•
recycling homogeneous catalysts

Recently ionic liquids have often been
discussed as promising solvents for “clean
processes” and “green chemistry”.
These two catchwords means to reduce drastically
the amounts of side and coupling products and
the solvent and catalyst consumption in chemical
processes.
What is “green chemistry” ?

ILs are environmentally-friendly alternatives to
organic solvents for liquid/liquid extractions.
Catalysis, separations, and electrochemistry.

ILs will reduce or eliminate the related costs,
disposal requirements, and hazards associated
with volatile organic compounds (VOCs).

The ability to fine-tune the properties of the IL
medium will allow selection of IL to replace
specific solvents in a variety of different processes.
Why consider Ionic liquids ?
Important IL Properties

High ionic conductivity

Non-flammable

Non-volatile

High thermal stability


Wide temperature range for liquid phase (- 40
to + 200°C)

Highly solvating, yet non-coordinating

Good solvents for many organic and inorganic
materials
Great promise

Designability. By combining different anions with
cations, it is possible to generate a huge number of
different ionic liquids, each with their own specific
solvent properties. Some ionic liquids are water
soluble, others are not. Some dissolve typical organic
solvents, other are not.

They can be functionalized to act as acids, bases or
ligands and have the potential to catalyze certain
reactions in certain systems.

Ionic liquids are non-volatile, hence they may be used
in high vacuum systems and high temperature
reactions without the requirement of a pressure vessel
to contain the vapors.

They are good solvents for a wide range of both
inorganic, organic and polymeric materials and
unusual combinations of reagents can be
brought into same phase. However they do not

dissolve glass, polyethylene, or Teflon. High
solubility usually implies small reactor volumes
in the final process.

They are immiscible with a number of organic
solvents and provide a non-aqueous, polar
alternative for two phase systems, this has been
used to effect total catalyst recovery in a
number of transition metal catalyzed reactions.
Hydrophobic ionic liquids can also be used as
immiscible polar phase with water.

They are often composed of poorly coordinating
ions, so they have the potential to be highly
polar non-coordinating solvents, this is
particularly important when using transition-
metal based catalysts.
Characteristics of RTIL

Choice of cation and anion determine physical
properties (e.g. melting point, viscosity, density, water
solubility, etc.)

Cations are typically big, bulky, and asymmetric
accounting for the low melting points

The anion contributes more to the overall
characteristics of the IL and determines the air and
water stability


Melting point can be easily changed by structural
variation of one of the ions or combining different
ions
•
Room temperature ionic liquids consist of bulky
and asymmetric organic cations such as :
Imidazolium ion Pyridium ion Ammonium ion Phosphonium ion
Scheme 1. Important types of cation
Typical RTIL Cations
•
A wide range of anions is employed, from simple
halides which inflect high melting points, to
inorganic anions such as:
Anions:
Anions for RTIL
Comparison of organic solvents with ionic
liquids
Further information regarding physical properties, chemistry, and uses of
ionic liquids:
[1] Welton T. Chem . Rev., 1999, 99: 2071.
[2] Wasserscheid P, Keim W. Angew Chem. .Int. Ed. Engl., 2000, 39: 3722.
[3] Freemantle M. (a) Chem . Eng . News, 2000, 78 (May)15: 37-39; (b) Chem .
Eng . News, 2001, 79 (Jan)1: 21-25.
[4] Earle M J, Seddon K R. Pure Appl, Chem., 2000, 72 (7): 1391-1398.
[5] Chum H L, Koch V N et al. J. Am. Chem, Soc., 1975, 97: 3264 .
[6] Wilkes JS et al . Inorg . Chem., 1982, 21: 1236.
[7] a) Blanchard L A et al. Nature, 1999, 399: 28; b) Blanchard L A et al. Ind. Egn.
Chem. Res., 2001, 40: 287.
[8] Chauvin Y, Muβmann L, Olivier H. Angew. Chem. Int. Engl., 1995, 34: 2698.
[9] Monteiro A L et al. Tetrahedron Asymmetry, 1997, 2: 177-179.

[10] Song C E, Roh E J. Chem. Commun., 2000: 837-838.
[11] Dullins J E L et al. Organometallics, 1998, 17: 815.
[12] Kakfman D E et al. Synlett., 1996: 1091.
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