Weird mixtures replace toxic solvents

日期:2018-01-16 03:22:30 作者:高励 阅读:

By Lila Guterman EXOTIC liquids that behave like molten crystals could reduce the quantity of noxious organic solvents used in industry. Industrial chemists often need to isolate compounds from mixtures. If the desired compound is less soluble in water than in an organic solvent, it can be isolated by shaking with both water and solvent. When this mix settles, two layers form, with the target compound concentrated in the upper, organic layer. The problem is that most organic solvents are toxic and flammable, and evaporate easily to create noxious smogs. But Robin Rogers and his colleagues at the University of Alabama in Tuscaloosa say dangerous solvents can be replaced by ionic liquids made of negative and positive ions that slosh around freely, rather than being held in a crystal lattice. The liquid studied by Rogers consists of positive ions of butylmethylimidazolium and negative hexafluorophosphate ions. Compounds that are more soluble in organic solvents than in water are highly soluble in this liquid. When mixed with water it sinks to form a layer that doesn’t evaporate (Chemical Communications, 1998,