Fluorocarbon extraction

In conclusion, we have successfully demonstrated that, by using a fluorous label and a fluorous solvent, we can affect the phase transfer of gold and CdSe nanoparticles from an aqueous or hydrocarbon medium to the fluorous phase. Single-walled carbon nanotubes and ZnO nanorods can be solubilized in a fluorous solvent after interaction with a fluorous amine. Phase transfer of the nanostructures to a fluorous solvent represents solubilization in a highly nonpolar solvent, accompanied by purification. The high nonpolarity of the fluorocarbon makes it possible to study the optical and other properties of nanostructures in a medium of very low refractive index. Since the fluorocarbon extracts only the species attached to the fluorous label, the process enables one to obtain solely one product in the pure state. We believe that fluorous chemistry may have practical utility in carrying out studies of nanostructures. 

Principles and Characteristics In the Parr bomb extraction technique (see also Section 8.2.1.2), a Teflon-tetrafluoroethylene fluorocarbon resin lined vessel is used for sample containment. A sample (typically 1 g) is heated in a small volume of solvent at T, t, p of choice. 

Mixtures of 25-30% fluorine diluted with nitrogen were used in this work. The gas mixtures were prepared in a secondary container. The appropriate polyether was dissolved either in perfluoro-2-butyl-THF (FC-75) or in Krytox GPL 100 (a fluorinated oil), which also contained about 5 g of pulverized NaF to absorb the relased HE The reaction mixture was cooled to - 10°C, stirred with the aid of a vibromixer and irradiated with a 450-W medium-pressure mercury lamp. A stream of fluorine in nitrogen (ca. 140 ml/min) was passed into the mixture such that the temperature did not rise above +10°C. The reaction was stopped after 200 mmol of fluorine had been passed through. The mixture was poured into water and the organic layer was washed with sodium bicarbonate solution. The water layer was extracted twice with CFCL. The combined fluorocarbon fractions were washed with water, dried with MgS04, and filtered, and the solvent was removed under reduced pressure. 

The ores from which rare-earth elements are extracted are monazite, bastnasite, and oxides of yttrium and related fluorocarbonate minerals. These ores are found in South Africa, Australia, South America, India, and in the United States in Cahfomia, Florida, and the Carolinas. Several of the rare-earth elements are also produced as fission by-products during the decay of the radioactive elements uranium and plutonium. The elements of the lanthanide series that have an even atomic number are much more abundant than are those of the series that have an odd atomic number. 

A similar approach has been taken for preparing molecularly controlled siloxane networks [440,446]. Composite bilayer films were cast from mixtures of alkoxysilane (CH3Si(OCH3)3) and 37 or 38 on a fluorocarbon sheet and were kept at 25 °C and 60% relative humidity for three days. Exposure to gaseous ammonia in a closed vessel for ten days resulted in hydrolysis and subsequent condensation. The surfactants were then extracted by repeated immersion in methanol. Manipulation of the composition of the cast multibilayers allowed... 

A mixture of 1//-decafluoroheptane (24.7g, 67mmol), NOz (6.6g), and Cl2 (5.2g) (molar ratio 1 2 1) was passed through the reactor (sloping 52 x 2.5 cm empty Ni pipe in a 33-cm electric tube furnace) at a wall temperature of 600 C in 15 min with a contact time of 11 s. The product in the ice trap (17.8 g) was hydrolyzed in cold H20 (100 mL), and coned H2S04 (25 mL) was added which caused the separation of a lower phase containing theperfluoro acid. The aqueous phase was extracted with perfluoro inert c-C6F 20 (a cyclic ether), in which fluorocarbon acids are soluble. The lower layer was separated and the product was recovered from the perfluorinated solvent by distillation yield 11.1 g(46%) bp 170-175 C/740Torr. 

An acid extraction was prepared on all samples and was carried out in the manner described later. After extraction, all samples were filtered with 0.45-/zm fluorocarbon filters. Twenty microliters of solution was used for each analysis on a Perkin-Elmer series 10 HPLC. Each sample was allowed to run 20 min, and the results were printed by computer. The column used was a 10-cm C-18 reverse-phase 10-/zm Perkin-Elmer column with an Alltech precolumn attached. The detector used was a Perkin-Elmer model LC-15 UV detector set at 254 nm. 

Only perfluorocyclopentene has been synthesised directly by this route it can be seen that, here, allylic rearrangements can occur to make all positions potentially vinylic and therefore reactive [64]. An analogous situation applies to hexachlorobutadiene. These reactions may also be carried out with potassium fluoride that has been exposed to Sulpholan or 18-crown-6, but then suspended in a fluorocarbon. Under these conditions, a significant proportion of hexafluoro-2-butyne is formed, presumably because the latter is extracted into the fluorocarbon, pre-empting further reaction with fluoride [65] (Figure 2.14). 

Chloroform is a volatile, low-molecular weight, lipophilic compound and a chlorinated trihalo-metheane. Most of the chloroform produced in the United States is used to make fluorocarbon 22 (HCFC 22) and the rest is produced for export and miscellaneous uses. In the past it was used as an inhalation anesthetic and as an extraction for, fats, oils, greases and other products, as a dry cleaning spot remover, in fire extinguishers, and as a fumigant. It is available as emulsions, spirits, tinctures, and chloroform water. Chloroform is also formed as a by-product of chlorination of water, wastewater, and swimming pool. Other sources include pulp and paper mills, hazardous waste sites, and sanitary landfills. 

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