Perfluorocarbons solubility

M. Cavazzini, F. Montanari, G. Pozzi, S. Quia, Perfluorocarbon-Soluble Catalysts and Reagents and the Application of FBS (Fluorous Biphase System) to Organic Synthesis , J. Fluorine Chem. 1999, 94,183. 

The first example of FB oxidation of sulfides dates back to 1995 dibenzothiophene and diphenyl stdfide gave the corresponding sulfones in low yields (1.4% and 10%, respectively) upon treatment with O2 at 100 °C in the presence of a not fully characterized perfluorocarbon-soluble iron—phthalocyanine [19]. Following this earlier report, Co(ll)—tetraarylporphyrin Co-5 and Co(I I [—phthalocyanine Co-12 (cf Stmcture) were tested as catalysts for the FB oxidation of methyl phenyl sulfide and para-substituted aryl methyl sulfides with O2 and a sacrificial aldehyde (Table 3) [20]. 

Alkane and Alkene Oxidation with Perfluorocarbon Soluble Metalloporphyrins as Catalysts... 

The ultrasound contrast agents are manufactured from nontoxic natural or synthetic biodegradable materials (e.g., lipids or proteins), and a small amount of an inert low-solubility non-reactive gas (e.g., perfluorocarbon). These components have been shown to be harmless to the patient unlike the tens of milliliters of concentrated viscous solutions of the widely used X-ray contrast agents (which may sometimes result in nephrotoxicity). 

Fig. 3. Oxygen transport by perfluorocarbons versus hemoglobin (Hb) (a) In the case of PFCs, O2 dissolution is characterized by loose, nondirectional van der Waals interactions. Oxygen solubility follows Henry s law, that is, is directly proportional to the gas s partial pressure (curve c). (b) In the case of Hb, a strong, localized chemical bond is established with the iron atom of a heme. Successive binding of four O2 molecules to the four hemes of Hb is cooperative, and saturation occurs when all four iron atoms are bound. Hence, the sigmoid shape of the O2 uptake curve, which levels off when the partial pressure of O2 on earth is attained (curve d) [20].

In the Liquid-Phase Photofluorination [39,44] process the reactant is injected at a very slow constant rate into an inert fluorocarbon solvent which is saturated by fluorine and under U.V. irradiation. Conditions are chosen to ensure that the concentration of fluorine and fluorine radicals is always much higher than the concentration of the substrate. This method is only suitable for the perfluorination of substrates, such as partially fluorinated ethers (see Section 2.5) and amines (see Section 2.7), that are both soluble in perfluorocarbon solvents and can withstand such vigorous reaction conditions. 

Perfluorocarbons. In 1966, it was demonstrated (27) that a laboratory mouse could survive total immersion in a perfluorochemical (PFC) solution. This material, similar to commercial Teflon, is almost completely inert and is insoluble in water. A water-soluble emulsion was prepared that could be mixed with blood (28), and in 1968 (29) the blood volume in rats was completely replaced with an emulsion of perfluorotributylamine [311-89-7], C12F27N. The animals survived in an atmosphere of 90—100% 02 and went on to long-term recovery. However, the 02 content of the perfluorochemicals has a linear dependence on the partial pressure of oxygen, P, as can be seen in Figure 1. The very high 02 tension required to transport physiologic amounts of 02 (12) and the propensity of the perfluorocarbon to be taken up by the reticuloendothelial cells were considered to be severe limitations to the development of clinically useful perfluorocarbon blood substitutes (30). 

A surfactant molecule is an amphiphile, which means it has a hydrophilic (water-soluble) moiety and a hydrophobic (water-insoluble) moiety separable by a mathematical surface. The hydrophobic tails of the most common surfactants are hydrocarbons. Fluorocarbon and perfluorocarbon tails are, however, not unusual. Because of the hydrophobic tail, a surfactant resists forming a molecular solution in water. The molecules will tend to migrate to any water-vapor interface available or, at sufficiently high concentration, the surfactant molecules will spontaneously aggregate into association colloids, i.e., into micelles or liquid crystals. Because of the hydrophilic head, a surfactant (with a hydrocarbon tail) will behave similarly when placed in oil or when put in solution with oil and water mixtures. Some common surfactants are sodium or potassium salts of long-chained fatty acids (soaps), sodium ethyl sulfates and sulfonates (detergents), alkyl polyethoxy alcohols, alkyl ammonium halides, and lecithins or phospholipids. 

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