Catalysis ILs improve the catalytic performance of
palladium nanoparticles. Furthermore, ionic liquids can be used as
pre-catalysts for chemical transformations. In this regard dialkylimidazoliums such as [EMIM]Ac have been used in the combination with a base to generate
N-heterocyclic carbenes (NHCs). These imidazolium based NHCs are known to catalyse a number transformations such as the
benzoin condensation and the OTHO reaction.
Pharmaceuticals Recognizing that approximately 50% of commercial pharmaceuticals are salts, ionic liquid forms of a number of pharmaceuticals have been investigated. Combining a pharmaceutically active cation with a pharmaceutically active anion leads to a Dual Active ionic liquid in which the actions of two drugs are combined. ILs can extract specific compounds from plants for pharmaceutical, nutritional and cosmetic applications, such as the
antimalarial drug
artemisinin from the plant
Artemisia annua.
Biopolymer processing The dissolution of
cellulose by ILs has attracted interest. A patent application from 1930 showed that 1-alkylpyridinium chlorides dissolve cellulose. Following in the footsteps of the
lyocell process, which uses hydrated
N-methylmorpholine N-oxide as a solvent for pulp and paper. The "valorization" of cellulose, i.e. its conversion to more valuable chemicals, has been achieved by the use of ionic liquids. Representative products are glucose esters,
sorbitol, and alkylgycosides. IL 1-butyl-3-methylimidazolium chloride dissolves
freeze-dried banana pulp and with an additional 15%
dimethyl sulfoxide, lends itself to
carbon-13 NMR analysis. In this way the entire complex of
starch,
sucrose,
glucose, and
fructose can be monitored as a function of banana ripening. Beyond cellulose, ILs have also shown potential in the dissolution, extraction, purification, processing and modification of other
biopolymers such as
chitin/
chitosan,
starch,
alginate, collagen,
gelatin,
keratin, and
fibroin. For example, ILs allow for the preparation of biopolymer materials in different forms (e.g. sponges, films, microparticles, nanoparticles, and aerogels) and better biopolymer chemical reactions, leading to biopolymer-based drug/gene-delivery carriers.
Nuclear fuel reprocessing The IL 1-butyl-3-methylimidazolium chloride has been investigated for the recovery of
uranium and other metals from spent
nuclear fuel and other sources.
Solar thermal energy ILs are potential heat transfer and storage media in
solar thermal energy systems. Concentrating solar thermal facilities such as
parabolic troughs and
solar power towers focus the sun's energy onto a receiver, which can generate temperatures of around . This heat can then generate electricity in a steam or other cycle. For buffering during cloudy periods or to enable generation overnight, energy can be stored by heating an intermediate fluid. Although nitrate salts have been the medium of choice since the early 1980s, they freeze at and thus require heating to prevent solidification. Ionic liquids such as [C4mim][] have more favorable liquid-phase temperature ranges (−75 to 459 °C) and could therefore be excellent liquid thermal storage media and heat transfer fluids.
Waste recycling Ionic liquids have been investigated as solvents and reaction media for recycling processes, including polymer recycling and metal recovery. In polymer recycling, ionic liquids can support selective dissolution and purification steps in solvent-based recycling, and they have also been explored as media that influence depolymerization pathways for some condensation polymers (e.g., polyamides and polyesters). For practical implementation, efficient recovery and reuse of the ionic liquid is generally considered important due to cost and sustainability considerations.
Batteries ILs can replace water as the electrolyte in
metal-air batteries. ILs are attractive because of their low vapor pressure. Furthermore, ILs have an
electrochemical window of up to six volts (versus 1.23 for water) supporting more energy-dense metals. Energy densities from 900 to 1600 watt-hours per kilogram appear possible.
Dispersing agent ILs can act as
dispersing agents in
paints to enhance finish, appearance, and drying properties. ILs are used for dispersing
nanomaterials at IOLITEC.
Carbon capture ILs and
amines have been investigated for capturing
carbon dioxide and
purifying natural gas.
Tribology Some ionic liquids have been shown to reduce friction and wear in basic
tribological testing, and their polar nature makes them candidate
lubricants for
tribotronic applications. While the comparatively high cost of ionic liquids currently prevents their use as neat lubricants, adding ionic liquids in concentrations as low as 0.5 wt% may significantly alter the lubricating performance of conventional base oils. Thus, the current focus of research is on using ionic liquids as additives to lubricating oils, often with the motivation to replace widely used, ecologically harmful
lubricant additives. However, the claimed ecological advantage of ionic liquids has been questioned repeatedly and is yet to be demonstrated from a
life-cycle perspective. ==Safety==