Fluorohydrocarbons

Flnoromethane has been nsed as a selective inhibitor of ammoninm oxidation and nitrification-linked synthesis of N2O in Nitrosomonas europaea (Miller et al.l993), while difluoromethane has been proposed as a reversible inhibitor of methanotrophs (Miller et al. 1998). 

Monooxygenation is distributed among a variety of bacteria and several have been examined for their potential to degrade fluorinated alkanes  

Ammonia monooxygenase in Nitrosomonas europaea is able to oxidize fluoromethane to formaldehyde (Hyman et al. 1994). 

The methanotroph Methylosinus trichosporium strain OB3b that produces the soluble MMO system consisting of a 40 kDa NADH oxidoreductase, a 245 kDa hydroxylase, and a 16 kDa protein termed component B has a low substrate specificity (Sullivan et al. 1998). 

It has been shown to metabolize trifluoroethene to glyoxylate, difluoroacetate, and the rearranged product trifluoroacetaldehyde (Fox et al. 1990). The last reaction is analogous to the formation of trichloroacetaldehyde from trichloroethene by the same strain (Oldenhuis et al. 1989). 

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Chlorohydrocarbon Bp, °C Fluorohydrocarbon CAS Registry Number Bp, °C Difference per F atom, °C... 

Peroxvaad oxidation of bridged 5,6,7,8-tetrafluoro 1 4-dihydronaphthalene-1,4 imines gives aromatic fluorohydrocarbons by elimination of the imine bridge [91] (equation 84) Almost the same yields are achieved by oxidation with 30% hydrogen peroxide m refluxing methanol [91]... 

Carboxylic acids with a halide, hydroxy or amino group in the a-position form no dimers (Table 2, No. 11), except when two or three fluorine atoms are pr ent there (Table 2, No. 12). A large amount of work has been devoted to the coupling of fluoro-carboxylic acids (Table 2, Nos. 13-16) due to interesting properties of the produced fluorohydrocarbons. By statistical analysis optimal conditions for Kolbe ela trolysis of perfluorinated acids have been calculated [135]. 

Hydroxypropylmethylcellulose HPMC Cold water, GI fluids, methanol/methylene chloride, alcohol/fluorohydrocarbons Excellent film former and readily soluble throughout GIT low-viscosity grades to be preferred, e.g., Methocel HG (Dow)... 

A high-speed sensor for the assay of dimethyl sulfide in the marine troposphere based on its CL reaction with F2 was recently reported [18]. Sample air and F2 in He were introduced at opposite ends of a reaction cell with a window at one end. The production of vibrationally excited HF and electronically excited fluorohydrocarbon (FHC) produced CL emission in the wavelength range 450-650 nm, which was monitored via photon counting. Dimethyl sulfide could be determined in the 0-1200 pptv (parts per trillion by volume) concentration range, with a 4-pptv detection limit. 

Finally, it should be stressed that C02 is not the only SCF to demonstrate potential use in hydrogenation reactions. While the established technology platform and largely benign character of scC02 make it the current preferred choice, other SCFs may possess complementary properties in terms of polarity, solvation, and reactivities. In future, it is possible that alkanes (e.g., ethane and propane), fluorohydrocarbons and more reactive SCFs such as N20 - or even water - may also be envisaged for this purpose. 

For use in a radioactive environment the gas centrifuge must be completely maintenance free. It has been used for the separation of xenon isotopes and consideration has been given to its application for separation of fluorohydrocarbons. Worldwide, in the region of a quarter of a million gas centrifuges have been manufactured. As an order of magnitude figure, an investment of 1000 is necessary to obtain 0.3 g/s (10 g/h) of product. 

It is also important to recognize that unique differences should be anticipated in the plasma chemistry of fluorocarbons from that of hydrocarbons. This can be attributed in part to the strong C—F bond and relatively weak F—F bond. Thus, while elimination of and HF is a favorable process in the case of hydrocarbons and fluorohydrocarbons, for fluorocarbons C—C bond cleavage is mere likely. For example ... 

Although to-date the emphasis has been on plasma polymerized films produced from hydrocarbon based systems, this trend in more recent times has swung towards fluorocarbons in an attempt to produce polymers of similar properties to conventionally prepared linear fluoropolymers. However, it will become clear from the account to follow that in many respects plasma polymerized fluorocarbons differ significantly from their linear counterparts. It is to the plasma polymerization of organic monomers containing solely carbon and fluorine therefore that we shall devote our attention in this section with only brief references to hydrocarbon and fluorohydrocarbon polymers for comparison purposes. 

Adamantane and other tertiary hydrocarbons have been converted by applying this method [nitrosonium tetrafluoroborate/pyridinium poly(hydrogen fluoride) (PPHF)] into the corresponding fluorohydrocarbons in excellent yields.88... 

Conversion of Tertiary Hydrocarbons to Fluorohydrocarbons with NO+BF4/PPHF General Procedure 88... 

Elimination of hydrogen fluoride can be achieved thermally, catalytically, or by using alkaline agents. Phosphate salt catalysts are used in the dehydrofluorination of fluorohydrocarbons. 1,1.1-Trifluoroethane (23) on heating with magnesium phosphate at 450 C gives 1,1-difluoro-ethene (15).21... 

The flavour and modern phytopharmaceutical industries have made big changes to the traditional pharmaceutical extraction processes. Whereas ethanol was really the only significant solvent apart from water used by the traditional pharmaceutical extractors, solvents such as hexane and acetone have been used by flavour companies to make soft-extract oleoresins for natural flavour components. Sub- and supercritical carbon dioxide and also some fluorohydrocarbons are now used to produce some very high-quality extracts. Modern concentration and drying processes such as reverse osmosis, spray-drying and freeze-drying... 

The magnitude of one-bond fluorine coupling to carbon in a simple fluorohydrocarbon can vary from 151 to 280 Hz, depending again on whether one, two, or three fluorines are bound to the carbon. Scheme 2.22 demonstrates these trends in the fluoromethanes and fluoroalkanes. The scheme also includes mention of the one-bond H-C... 

The introduction of fluorine into the elastomeric macromolecule generally produces materials exhibiting an improved retention of properties at high temperatures, an improved flexibility at low temperatures, and an improved resistance to solvents. Essentially, there are two groups of fluoroelastomers fluoro-inorganic elastomers and fluorocarbon (or fluorohydrocarbon) elastomers. 

In Eq. (24), Hughes proposed that H2 displaces H20 and transfers a proton to form HF and a carbene ligand that is then hydrogenated to give a fluorohydrocarbon product [Eq. (25)] (93). 

Next these authors measured line widths for a series of fluorohydrocar-bons, CnH,Fm. The 7-ray spectrum for each was analyzed into components from the hydrogen and fluorine analogs, CnH +ro and CnF +m. The relative weight of the C F +m component was interpreted to be the fraction of annihilation on fluorine in C F +m. This fraction was then normalized by the fraction of valence electrons on F (assumed to be 8) in the molecule to account for annihilation in the C-C bond. The normalized fractions of annihilation on F for a large number of fluorohydrocarbons was found to be equal to the fraction of valence electrons on F in each molecule, to a good approximation. The conclusion of these authors is that annihilation in these molecules takes place with equal probability on any valence electron regardless of what atom it resides on. This is counterintuitive. 

Solvent in the dry-cleaning industry degreasing solvent in metal industries a heat-transfer medium manufacture of fluorohydrocarbons... 

Fischer and Hausser (44) have also observed hyperfine splittings in the AMg=2 line of some fluorohydrocarbons. These observations will undoubtedly have great significance in photochemical studies of excited triplet states since they allow the convenience of rigid glass technique to yield important information about the distribution of unpaired electrons in the excited state. 

The facts found with pulsed radio frequency discharge that (1) the largest increase in dangling bonds is observed with ethylene and fluorohydrocarbons (e.g., vinyl fluoride and vinylidene fluoride), (2) the dangling bonds in tetrafluoro-ethylene decrease, and (3) dangling bonds in most perfluorocarbons decrease support a significant difference between the plasma polymerization of hydrocarbons and that of perfluorocarbons summarized above. 

The carbon-tellurium bond linking tellurium to the perfluoroalkyl groups in perfluoroalkyl telluriums is cleaved by potassium hydroxide liberating fluorohydrocarbons. ... 

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