From curiosities to commodities2



How much $ ?Until 2001 one of the principal challenges to be addressed before ionic liquids can be used routinely was cost: a pound of ionic liquid had a cost of about 30,000 - fold greater than a common organic solvent such as acetone, the cost depending on the composition of the ionic liquid and the scale of production. However, because ionic liquids can be recycled, a little goes a long way.1

Nowadays a growing variety of ionic liquids are becoming commercially available, a development that will feed the surge of research using these unorthodox liquids.

Several start-up and established chemical manufacturers have “crossed the Rubicon” and introduced commercial IL lines. Among the entries into this arena are Covalent Associates, Cytec, Merck (Darmstadt), Ozark Fluorine Specialties, Sachem and Solvent Innovation.
Certain of these companies provide investigational samples directly to researchers, while also selling materials through retailers like Aldrich and Strem. Another large retailer, Acros, markets research sized samples obtained from Seddon’s QUILL.

A selection of ionic liquids avaiable from commercial manufacturers.

A selection of ionic liquids avaiable from commercial manufacturers.

To date, commercial offerings of salts explicitly described as ionic liquids are largely imidazolium based. Notably, BASF  has recently disclosed the involvement of an imidazolium ionic liquid in a commercial process, the production of alkoxyphenyl phosphines. Other processes said to be poised for licensing such as the French Petroleum Institute’s butene–dimerization process, also feature imidazolium based ionic liquids.

Nevertheless, there is a degree of compositional variety amongst commercial imidazolium IL offerings. This diversity arises almost wholly from the pairing of a very small number of cations, principally imidazolium ones, with any of a growing number of anions.

The most commonly employed IL anions are polyatomic inorganic species. Most prominent among the these is PF6, a work-horse anion that Wilkes and Zaworotko paired with imidazolium cations in preparing early water-stable, hydrophobic IL. It and the related ion BF4 are probably the most common anions used in IL research. Other widespread fluorine anions are CF3SO3-and (CF3SO3)2N-.
In response to safety and cost concerns, some manufacturers – notably Solvent Innovation and Sachem – have introduced new ILs with non-fluorous anions. The principal offerings by Solvent Innovation in this category are IL featuring alkylsulfate anions, such as ECOENG 500; also Sachem, an established bulk chemicals producer, has recently introduced the Terrasail line of IL based upon the docusate anion.

While IL derived from polyatomic anions still dominate commercial offerings, this is beginning to change. Cytec has awakened to the fact that many phosphonium halides that it has offered for years for phase-transfer applications are ionic liquids in their own rights, and has recently reported on their industrial preparation. Sachem also produces salts that were developed as phase transfer catalysts, but that are functionally ionic liquids.

Top


Index
Index
Home Page
Home Page