Fluorides of Sulfur

Ionization potential (ev), 1st electron From spectrum Calculated 

Collision diameter of molecule, determined from viscosity 

The gas is colorless, odorless, nontoxic, and inert. It is not changed by electrical stress just below the corona point (82), but it is decomposed slowly by spark-over or corona electrical discharge (82, 272) giving lower fluorides of sulfur and fluorides of the metals used as the electrodes. It does not react with water or with a basic solution but it does react vigorously with a hot alkali metal. The gas is not toxic however, it has some depressant action upon the central nervous system (45) and has mild anesthetic properties (812). In spite of this, rats may live in an atmosphere of 80% SF6 and 20% 02 for periods up to one day with no signs of poisoning (187). 

Sulfur hexafluoride is sold in cylinders containing 100 lb of the material at about 3 per lb (1959 price). It is used as the electrical insulator in coaxial cables, high voltage X-ray transformers, and high voltage generators (35, 211). Its availability is a stimulus to research dealing with the substance. Many studies use the substance because it is inert or because it is made up of nearly spherical molecules. There is also much theoretical interest in its structure and in the nature of the chemical bond involved. Many studies are related to its usefulness as an electrical insulator. 

Physical properties of sulfur hexafluoride are listed in Table I. These include various values of the critical constants. Several excellent studies of the critical phenomena have been made to learn whether the predictions of Harrison and Mayer (125) are correct. They suggested in 1938 that there could be a range of temperature above the observed critical point (disappearance of meniscus) in which the slope of pressure versus volume isotherms is zero. Their arguments have been criticized by Zimin (334) in 

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All of the fluorides of sulfur are colorless gases and hquids. SFe has the highest density of any substance that boils below room temperature (5.107 times as dense as air). 

Table 15.5 lists some properties of the most stable fluorides of sulfur. The fluorides SF4 and S2F2 can be prepared from the reaction of SCI2 and Hgp2 at elevated temperatures both are... 

Some of the more complex oxo chlorides and oxo fluorides of sulfur are those shown in Table 15-6 along with their structures, where known. These structures were determined, in large part, from 19F-nmr studies. 

Sulfur hexafluoride (CAS 2551-62-4) Considered to be essentially a nontoxic gas. Asphyxiation by the displacement of air is suggested as the greatest hazard. 1000 ppm Odorless, colorless dense gas. May be contaminated with other fluorides of sulfur, including the highly toxic sullur pentafluoride, which release HF or oxy-iluorides on contact with moisture. 

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. 

The highest fluoride of oxygen is the gas OF2 the highest fluoride of sulfur is... 

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