Carbon hexafluoride

Specifications and Analytical Methods. Sulfur hexafluoride is made to rigid specifications. Per ASTM D2472-81 (reapproved 1985) (50), the only permissible impurities are traces of air, carbon tetrafluoride (0.05 wt % max), and water (9 ppm by wt max dew point —45° Cmax). 

Depending on the ring substituent, trifluoromethoxyben2enes can be made by the sequential chlorination—fluorination of anisole(s) (351—354). A one-step process with commercial potential is the BF (or SbF2)-cataly2ed reaction of phenol with carbon tetrachloride/hydrogen fluoride (355). Aryl trifluoromethyl ethers, which may not be accessible by the above routes,may be made by fluorination of aryl fluoroformates or aryl chlorothioformates with sulfur tetrafluoride (348) or molybdenum hexafluoride (356). 

A number ot aryl trifluoromethyl ethers are synthesized by fluormation of aryl chlorothioformates with molybdenum hexafluoride. The reagents are progressively heated from -25 to 130 C, and the products are distilled off. Molybdenum disulfide and carbon disulfide are the by-products [12] (equation 16)... 

Write the formulas for the following compounds and give the weight of one mole of each carbon disulfide, sulfur hexafluoride, nitrogen trichloride, osmium tetroxide. 

A disadvantage of supercritical fluids for extraction is that most common fluids used for extraction (carbon dioxide, nitrous oxide, sulfur hexafluoride, etc.) are weak solvents, limiting the polarity and molecular weight range of analytes that can be efficiently extracted. Also, for trace analysis the availability of fluids of adeguate ptirity may be a problem. 

The flame ionization detector Is the most popular of the flame-based detectors. Apart from a reduction in sensitivity compared to expectations based on gas chromatographic response factors [138] and incompatibility with the high flow rates of conventional bore columns (4-5 mm I. 0.), the flame ionization detector is every bit as easy to use in SFC as it is in gas chromatography [148,149]. It shows virtually no response to carbon dioxide, nitrous oxide and sulfur hexafluoride mobile phases but is generally incompatible with other mobile phases and mixed mobile phases containing organic modifiers except for water and formic acid, other gas chromatographic detectors that have been used in SFC include the thermionic ionization detector (148,150], ... 

Sulphur dioxide Sulphur hexafluoride C T O Most common metals for dry gas. Lead, carbon, aluminium and stainless steel for moist gas Most common metals. Copper, stainless steel and aluminium are resistant to the decomposition products at 150°C Zinc... 

Ans. (a) Carbon monoxide, (b) sulfur dioxide, (c) sulfur trioxidc, (d) carbon tetrachloride, (e) phosphorus pentachloride, and (/) sulfur hexafluoride. 

Write formulas for each of the following compounds (a) carbon tetrabromide, (b) sulfur dibromide, and (c) sulfur hexafluoride. 

It explodes on contact with carbon tetrachloride or sulfur hexafluoride, and contact with chloroform causes incandescence. Disilane ignites spontaneously in air, even when pure, and ingress of air or oxygen into a volume of disilane causes explosion. 

AUC [Ammonium uranyl carbonate] A process for converting uranium hexafluoride into uranium dioxide for use as a nuclear reactor fuel. The hexafluoride vapor, together with carbon dioxide and ammonia, are passed into aqueous ammonium carbonate at 70°C, precipitating ammonium uranyl carbonate ... 

Carbon dioxide (C02), methane (CH4), nitrons oxide (N20), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF6). 

The first use of supercritical fluid extraction (SFE) as an extraction technique was reported by Zosel [379]. Since then there have been many reports on the use of SFE to extract PCBs, phenols, PAHs, and other organic compounds from particulate matter, soils and sediments [362, 363, 380-389]. The attraction of SFE as an extraction technique is directly related to the unique properties of the supercritical fluid [390]. Supercritical fluids, which have been used, have low viscosities, high diffusion coefficients, and low flammabilities, which are all clearly superior to the organic solvents normally used. Carbon dioxide (C02, [362,363]) is the most common supercritical fluid used for SFE, since it is inexpensive and has a low critical temperature (31.3 °C) and pressure (72.2 bar). Other less commonly used fluids include nitrous oxide (N20), ammonia, fluoro-form, methane, pentane, methanol, ethanol, sulfur hexafluoride (SF6), and dichlorofluoromethane [362, 363, 391]. Most of these fluids are clearly less attractive as solvents in terms of toxicity or as environmentally benign chemicals. Commercial SFE systems are available, but some workers have also made inexpensive modular systems [390]. 

C to the corresponding hexafluoride . Above 300 it reacts with chlorine to form TcCl. as the major product. At elevated temperatures technetium combines with sulfur to give the disulfide TcSj, and with carbon to form the carbide... 

Nonmetals, such as sulfur, phosphorus and carbon (amorphous) inflame in fluorine forming their corresponding fluoro compounds, such as sulfur hexafluoride (SFe), phosphorus pentafluoride (PF5), and carbon tetrafluoride (CF4). 

Neptunium forms a number of halides in various oxidation states. These include tri-, tetra- and hexafluorides of compositions NpFs, NpF4, and NpFe, respectively trichloride, NpCF and tetrachloride, NpCh tribromide, NpBrs and the triiodide NpN. Neptunium fluorides are formed by heating neptunium dioxide at elevated temperatures with fluorine in the presence of hydrogen fluoride. The tetrachloride, NpCh is obtained similarly by heating the dioxide with carbon tetrachloride vapor at temperatures above 500°C. Neptunium tribromide and triiodide are prepared by heating the dioxide in a sealed vessel at 400°C with aluminum bromide and aluminum iodide, respectively. 

Most chemical properties of technetium are similar to those of rhenium. The metal exhibits several oxidation states, the most stable being the hep-tavalent, Tc +. The metal forms two oxides the black dioxide Tc02 and the heptoxide TC2O7. At ambient temperature in the presence of moisture, a thin layer of dioxide, Tc02, covers the metal surface. The metal burns in fluorine to form two fluorides, the penta- and hexafluorides, TcFs and TcFe. Binary compounds also are obtained with other nonmetaUic elements. It combines with sulfur and carbon at high temperatures forming technetium disulfide and carbide, TcS2 and TcC, respectively. 

Platinum Dichloride Platinum Dioxide Platinum Hexafluoride Platinum Monoxide Platinum Tetrachloride Plutonium Polonium Potassium Potassium Acetate Potassium Bicarbonate Potassium Bisulfide Potassium Borohydride Potassium Bromate Potassium Bromide Potassium Carbonate... 

Among potentially interesting solvents for enzymatic catalysis, carbon dioxide is the most widely nsed snpercritical fluid. However, there is a growing interest in using other supercritical fluids (e.g., ethylene, fluoroform, ethane, sulfur hexafluoride, and near-critical propane) (Kamat et al., 1995b). 

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