Hexafluoride Subject

In humans, inhalation of 80% sulfur hexafluoride and 20% oxygen for 5 minutes produced peripheral tingling and a mild excitement stage, with some altered hearing in most subjects. According to the ACGIH, the chief hazard, as with other inert gases, would be asphyxiation as a result of the displacement of air by this heavy gas. ... 

Human exposure has caused headache and dyspnea. Two subjects accidentally exposed to tellurium hexafluoride after leakage of 50g into a small laboratory experienced garlic breath, fatigue, a bluish-black discoloration of the webs of the fingers, and streaks on the neck and face. Complete recovery occurred without treatment. 

In a dried 25-mL Schlenk tube under a nitrogen atmosphere, a mixture of [Rh(COD)Cl]2 (4.9 mg, 0.01 mmol) and (N)-BINAP (13.8 mg, 0.022 mmol) was dissolved in 10 mL of 1,2-dichloroethane and stirred at room temperature for 1 minute. Then phenyl-propynoic acid 4-hydroxy-but-2-enyl ester (216 mg, 1.0 mmol) was added into the solution at room temperature under a nitrogen atmosphere. After stirring for 1 minute, a solution of silver antimonite hexafluoride (13.7 mg, 0.04 mmol) in 0.8 mL of 1,2-dichloroethane was added into the mixture in one portion via a syringe. The resulting turbid solution was stirred at room temperature for 10 minutes. TLC indicated that all the starting material was consumed and the reaction completed. The reaction mixture was directly subjected to column chromatography (silica gel, hexane/ethyl acetate 80/20) to afford 196.7 mg (91% yield, 99% ee (5)) of pure white solid. 

Plasma can also be effectively applied for etching layers of silicon doped with refractory or rare metals, semiconductors, or via interconnects made with rare or refractory metals. Some of those etching reactions are illustrated in Table 8-4. These processes normally use fluorine-containing gases as a feedstock and have hexafluorides as volatile etching products. However, chlorine is preferred in some specifle cases. Only the most common plasma etching systems are discussed here much more detail on the subject can be found, particularly in the reviews of Flamm (1989) and Orlikovsky (2000). 

Subsidiary corrosive placards are required for certain shipments of uranimn hexafluoride. Materials subject to the poison-inhalation hazard shipping paper description, and materials which have a subsidiaiy risk of being dangerous when wet require subsidiaiy placards. Other subsidiary placards are permitted, but not required and... 

Packages containing fissile material or uranium hexafluoride are subject to additional requirements. 

Liquid, solid, and gaseous materials have been used as PCB replacements. Some of these materials are suitable for retrofilling existing equipment, while others are manufactured solely for use in new equipment. Solid replacements are used in dry-type transformers, and include epoxy and PVC, while gaseous replacements include chlorofluorocarbons (freons) and sulfur hexafluoride. Liquid PCB replacements, which will constitute the subject of this chapter, are quite diverse, encompassing silicones, high-temperature hydrocarbons, synthetic esters, alkylated aromatics, chlorinated benzenes, and others. A brief summary of liquid replacement fluids is given in Table 1. 

Lower fluorides of sulfur, some of which are toxic, may be produced if sulfur hexafluoride is subjected to electrical discharge. Personnel must guard against the inhalation of the gas after electrical discharge. 

Sulfur hexafluoride is noncorrosive to all metals. It may be partially decomposed if subjected to an electrical discharge. Some of the breakdown products are corrosive this corrosion is enhanced by the presence of moisture or at high temperature. Sulfur hexafluoride decomposes very slightly in the presence of certain metals at temperatures in excess of 400°F (204°C) this effect is most pronounced with silicon and carbon steels. Such breakdown, presumably catalyzed by the metals, is only several tenths of 1 percent over 1 year. Decomposition at elevated temperatures does not occur with aluminum, copper, brass, and silver. 

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