Usually extractants have been used as solution in diluents. Diluent influences on properties of extraction mixture very significantly. Hydrocarbons are traditional diluents. Unfortunately, hydrocarbons are low-polar compounds and therefore are not good as diluents for polar extractants.
Fluorinated diluents are possible alternative for hydrocarbons ones. Best studied polar fluorinated diluent: meta- nitrobenzotrifluoride (F-3, MNBTF) was used as diluent for chlorinated cobalt dicarbollide in industrial scale. It was used also for many polar extractants – from carbamoylphosphine oxide to calixarenes and amides of heterocyclic acids. It's disadvantages - rather high solubility in acid solution and toxicity (because it’s nitroaromatic compound), were reduced by use of phenyl trifluoromethyl sulfone (FS-13, PMTS).
Fluorinated diluents without aromatic ring are more promising. Different classes of compounds - fluorinated alcohols, formals, esters and ethers of fluorinated alcohols were studied as diluents for crown-ethers, TBP, carbamoylphosphineoxides, amides of diglycolic acid etc.
The goal of the presented work is the review of history of fluorinated diluents use and discussion of possible ways of its future development.