Switching Philicity

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Science  24 Mar 2006:
Vol. 311, Issue 5768, pp. 1677
DOI: 10.1126/science.311.5768.1677a

The immiscibility of organic and aqueous solutions (such as oil and vinegar) underlies a wide range of practical chemical separations. For versatility, liquid fluorocarbons have come into increasing use over the past decade as a third solvent phase, into which highly fluorinated solutes partition from both water and the more traditional organic solvents.

Orita et al. were therefore surprised to find that a hydrated distannoxane complex bearing linear fluorocarbon tails—an Sn-O-Sn core with two C6F13C2H4 chains and a perfluorooctane sulfonate chain appended to each Sn—failed to dissolve in common fluorous solvents such as FC-72. The compound did dissolve in polar organic liquids (ethyl acetate, acetone, and tetrahydrofuran), and subsequently partitioned into the fluorous phase upon addition of FC-72 to the solution. The authors explain these observations by suggesting that the waters of hydration initially bound to the tin repel the fluorous solvent but can be displaced by polar organics, which in turn allows the fluorous liquid to approach. The compound proved useful as a homogenizing agent for fluorous and organic solvents, with 1.7 g nearly tripling the solubility of ethyl acetate in FC-72. — JSY

J. Am. Chem. Soc. 128, 10.1021/ja058105v (2006).

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