recent interest surrounding ILs in regards
Chemistry and the
associated development of new solvents and
alternative technologies has largely been a result of their
negligible vapour pressure
inhibits evaporation into the air and allows simple recycling
The missing vapour
pressure has very important advantages compared to
other volatile organic chemicals (VOCs).
Therefore ionic liquids are
not flammable and not explosive and a long range
distribution via air can not be expected.1,4,12
of Green Chemistry encompass a new
attitude toward industrial practices and chemical syntheses where
gaseous, liquid or solid wastes are not treated as inevitable
byproducts of the chemical manufacturing chemistry . Instead, the new
approach involves steps to decrease or eliminate the hazards in the
system and eliminate the waste before it is produced.4
potential of ILs to provide a nonvolatile
solvent system has become a practical target for reducing waste and
hazards by eliminating traditional volatile organic solvents.
is this already
sufficient for safe industrial chemicals of tomorrow?
excitement, chemists are cautious about too
much hype about ionic liquids' greenness:1
- "Before we can say
that ionic liquids are green, we
have to look at their entire life cycle. People are calling ionic
liquids green because they are not volatile, but we have to look at how
they are made all the way through to recycling and disposal"
- Robin Rogers,
director of the Center for Green
Manufacturing at the University of Alabama in Tuscaloosa.
issues need to be takled, before ionic liquids can be used routinely.
- In fact VOCs are
used to manufacture
ionic liquids, and the
ionic liquids themselves are
made from species that, before their combination, are VOCs. However,
already in 2001 there had been advances in the solventless synthesis of
ionic liquids, for instance Rajender Varma and Vasudevan Namboodiri at
EPA's National Risk Laboratory in Cincinnati, OH, prepared the
1-alkyl-3-methylimidazolium halides in open containers in a microwave
oven without any solvents.
- Researchers also need to find better ways to recycle
Many processes for cleaning up ionic liquids involve washing with water
needs more work, we don't
to create a secondary waste "
- Robin Rogers, first major US meeting on ionic
liquids, held in 2001 at the American Chemical Society meeting in San
For example, in 2001 Notre Dame researcher Joan Brennecke succesfully
removed dissolved organic compounds from ionic liquids using
supercritical CO2, while Roger and Davis clean the ionic
liquids in their contaminated metal process by heating under a vacuum.1
what about toxicological and
eco-toxicological effects of ionic liquids?
let's have a
look at ILs' Toxicology...