Sulfur metal fluorides

The reactivity of fluorine compounds varies from extremely stable, eg, compounds such as sulfur hexafluoride [2551-62 ] nitrogen trifluoride [7783-54-2] and the perfluorocarbons (see Fluorine compounds, organic) to extremely reactive, eg, the halogen fluorides. Another unique property of nonionic metal fluorides is great volatiUty. Volatile compounds such as tungsten hexafluoride [7783-82-6] molybdenum hexafluoride [7783-77-9] ... 

Sulfuric acid loss is approximately 1.84% H2SO4 for each percentage of R2O2. Oleum consumption is increased to consume the water that is formed. The metal sulfates are more stable than metal fluorides under furnace conditions and are discharged from the process with the residue. 

Thiothionyl Fluoride and Difluorodisulfane. Thiothionyl fluoride [1686-09-9] S=SF2, and difluorodisulfane [13709-35-8] FSSF, are isomeric compounds which may be prepared as a mixture by the action of various metal fluorides on sulfur vapor or S2CI2 vapor. Chemically, the two isomers are very similar and extremely reactive. However, in the absence of catalytic agents and other reactive species, FSSF is stable for days at ordinary temperatures and S=SF2 may be heated to 250°C without significant decomposition (127). Physical properties of the two isomers are given in Table 6. The microwave spectmm of S=SF2 has been reported (130). 

Fluor-jod, n. iodine fluoride, -kalium, n. potassium fluoride, -kalzium, n. calcium fluoride, -kiesel, m. silicon fluoride, -kie-selsaure,/. fluosilicic acid, -kohlenstoff, m. carbon fluoride, -lithium, n. lithium fluoride. -metall, n. metallic fluoride, -natrium, n. sodium fluoride, -phosphat, n. fluophosphate. -phosphor, m. phosphorus fluoride, -salz, n. fluoride, -schwefel, m. sulfur fluoride, -selen, n. selenium fluoride, -silber, n. silver fluoride, -silikat, n. fluo-silicate. -silizium, n. silicon fluoride, -sili-ziumverbindung, /. fluosilicate. -tantal-sMure, /. fluotantalic acid, -tellur, n. tellurium fluoride, -titan, n. titanium fluoride, -toluol, n. fluorotoluene, fluotoluene. 

This indirect proof of the appearance of CF3SF leads to the conclusion that fluorination of sulfenyl chlorides of the series CF Cl3 SCl (n = 0, 1, 2) with alkali metal fluorides follows the mechanism observed in the formation of sulfenyl fluorides the initial chlorine-fluorine exchange at the sulfur atom is followed by isomerization to the sulfenyl chloride containing the corresponding more highly fluorinated methyl group. 

Selenium hexafluoride, SeFg, the only clearly defined hexahalide, is formed by reaction of fluorine with molten selenium, It is more reactive than the corresponding sulfur compound, SFs, undergoing slow hydrolysis. Selenium forms tetrahalides with fluorine, chlorine, and bromine, and dihalides with chlorine and bromine. However, other halides can be found in complexes, e.g,. treatment of the pyridine complex of SeF/i in ether solution with HBr yields (py)2SeBrc Selenium tetrafluoride also forms complexes with metal fluorides, giving MSeF complexes with the alkali metals. 

The fluorosulfonyl group as an excellent leaving group can be substituted by fluorine in aromatic and fluoroaliphaticcompounds. " Metal fluorides serve as the fluoride source. The fluoro-sulfinate anion cleaved oif decomposes into sulfur dioxide and fluoride. Therefore, at least in theory, only catalytic amounts of added fluoride are required. In practice there is a loss of fluorine by formation of thionyl fluoride, which has to be compensated for. 

The reaction of sulfur vapor with AgF at 125 °C gives FSSF. This in turn can be converted to the more stable isomer S=SF2 in the presence of alkali metal fluorides or BF3. Both isomers rapidly hydrolyze to give Sg, HF, and a mixture of polythionic acids, H2S 06 ( = 4-6). 

Disulfuryl fluoride is a clear colorless liquid with a boiling point of 51°. Its vapor pressure over the temperature range —28 to 43° follows the equation logioP(mm.) = 8.015— 1662/T. It has an inhalation toxicity of the same order as that of phosgene, and should be handled only in a well-ventilated area. Its thermal decomposition to sulfur trioxide and sulfuryl fluoride is not very appreciable below 200° but is rapid at 400-500°. In the presence of metal fluorides such as ceaum or sodium fluoride, however, its decomposition point is considerably low er. It hydrolyzes rather slowly to give fluorosulfuric acid. It is not very soluble in cold concentrated sulfuric acid or fluorosulfuric acid, but is soluble in acetonitrile, ethyl ether, carbon tetrachloride, monofluorotrichloromethane, and benzene. 

Derivation (1) Action of hydrogen fluoride or concentrated sulfuric acid and a metallic fluoride on silica or silicates (2) direct synthesis. 

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). 

The selective oxidation of ethylene to ethylene oxide (EO) is performed on supported silver catalysts at temperatures of250—280 °C, and a pressure of roughly 20 bar. In this process, it is necessary to avoid secondary reactions of EO. Typical industrial catalysts may contain 8—15 wt% silver dispersed on low surface area (X-AI2O3 (0.5-1.3 m g ) with a porosity of about 0.2—0.7 cm g In addition, the catalyst may contain several promoters in varying amounts (ppm by weight) 500—1200 ppm alkali metal (mostly cesium), 5-300 ppm of sulfur as cesium or ammonium sulfate, 10-300 ppm offluorine as ammonium fluoride, or alkaft metal fluoride (427). 

Sulfur dioxide reacts with O2 (see below), F2 and CI2 (equation 16.88). It also reacts with the heavier alkali metal fluorides to give metal fluorosulfites (equation 16.89), and with CsNg to give the Cs salts of [S02N3] (Figure 16.16a)... 

For the laboratory preparation of sulfur(VI) fluoride, coarsely crushed lump (roll) sulfur is placed in a steel, copper, or Monel container, such as a horizontal pipe, capped at each end and provided with suitable inlet and outlet tubes, or a metal box provided with shelves placed in such a manner as to permit a current of fluorine to circulate over the sulfur charge in a continuous manner. If a pipe is used, sufficient space is allowed above the charge of sulfur for free passage of the gas. ... 

For permanent storage the trap J containing the solid sulfur(VI) fluoride is connected through a ground joint to a metal system employed in transferring the contents to a steel cylinder. This metal system (conveniently made of copper or bronze) consists of a manifold tube leading from... 

The decomposition of inorganic substances can be accomplished with a mixture of hydrochloric and nitric acids in a closed vessel (pressure digestion). Silicate-containing minerals and glasses require the addition of hydrofluoric acid, and the presence of perchloric acid, phosphoric acid, or sulfuric acid is sometimes useful as well [80]. The resulting metal fluorides can be redissolved by adding a solution of boric acid. The same procedure is effective for ores and slags as well as quartz [81 j. 

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