Antimony pentafluoride

Antimony Pentafluoride. Antimony pentafluoride (SbF5) is a highly associated, colorless, very viscous liquid at room temperature. It is hygroscopic and fumes in moist air. Its viscosity at 20°C is 460 cP, which is close to that of glycerol. The pure liquid can be handled and distilled in glass if moisture is excluded. Commercial antimony pentafluoride is shipped in steel cylinders or in perfluoroethylene bottles for laboratory quantities. 

Ab initio molecular dynamics were used to investigate the structure of liquid SbF5. The results confirm the high tendency of SbF5 to oligomerize and impart a highly ionic character to the Sb-F bond. It confirms also the cw-bridged chain polymer as the most stable structure.39 

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My work on long-lived (persistent) carbocations dates back to the late 1950s at Dow and resulted in the first direct observation of alkyl cations. Subsequently, a wide spectrum of carbocations as long-lived species was studied using antimony pentafluoride as an extremely strong Lewis acid and later using other highly acidic (superacidic) systems. 

In eontrast, dialkylhalonium salts sueh as dimethylbromonium and dimethyliodonium fluoroantimonate, whieh we prepared from excess alkyl halides with antimony pentafluoride or fluoroantimonie acid and isolated as stable salts (the less-stable chloronium salts were obtained only in solution), are very effective alkylating agents for heteroatom eompounds (Nu = R2O, R2S, R3N, R3P, ete.) and for C-alkylation (arenes, alkenes). 

Fluorine reacts with the halogens and antimony to produce several compounds of commercial importance antimony pentafluoride [7783-70-2J, bromine trifluoride [7787-71 chlorine trifluoride [7790-91 -2J, and iodine pentafluoride [7783-66-6J. Chlorine trifluoride is used in the processing of UF (see Uraniumand uranium compounds). Bromine trifluoride is used in chemical cutting by the oil well industry (see Petroleum). Antimony and iodine pentafluorides are used as selective fluorinating agents to produce fluorochemical intermediates (see Fluorine compounds, inorganic). 

Properties. Antimony pentafluoride [7783-70-2], SbF, is a colorless, hygroscopic, very viscous liquid that fumes ia air. Its viscosity at 20°C is 460 mPa-s(=cP) which is very close to the value for glycerol. The polymerization of high purity SbF at ambient temperature can be prevented by addition of 1% anhydrous hydrogen fluoride, which can be removed by distillation prior to the use of SbF. The pure product melts at 7°C (11), boils at 142.7°C,... 

OSHA has a TWA standaid on a weight of Sb basis of 0.5 mg/for antimony in addition to a standard TWA of 2.5 mg/m for fluoride. NIOSH has issued a criteria document on occupational exposure to inorganic fluorides. Antimony pentafluoride is considered by the EPA to be an extremely hazardous substance and releases of 0.45 kg or more reportable quantity (RQ) must be reported. Antimony triduoride is on the CERCLA bst and releasing of 450 kg or more RQ must be reported. 

Antimony pentafluoride dissolves ia each to form BrF" 2 bB g 6 which act as acids. Potassium fluoride likewise forms KBrF [15705-87-0] and... 

For anhydrous hydrogen fluoride, the Hammett acidity function Hq approaches —11. The high negative value of Hq shows anhydrous hydrogen fluoride to be in the class of superacids. Addition of antimony pentafluoride to make a 3 Af solution in anhydrous hydrogen fluoride raises the Hammett function to —15.2, nearly the strongest of all acids (34). 

The only example of xenon in a fractional oxidation state, +, is the bright emerald green paramagnetic dixenon cation, Xe [12185-20-5]. Mixtures of xenon and fluorine gases react spontaneously with tiquid antimony pentafluoride in the dark to form solutions of XeF+ Sb2 F, in which Xe is formed as an iatermediate product that is subsequently oxidized by fluorine to the XeF+ cation (83). Spectroscopic studies have shown that xenon is oxidized at room temperature by solutions of XeF+ ia SbF solvent to give the XE cation (84). 

Lewis Acid Complexes. Sulfolane complexes with Lewis acids, such as boron trifluoride or phosphoms pentafluoride (17). For example, at room temperature, sulfolane and boron trifluoride combine in a 1 1 mole ratio with the evolution of heat to give a white, hygroscopic soHd which melts at 37°C. The reaction of sulfolane with methyl fluoride and antimony pentafluoride inhquid sulfur dioxide gives crystalline tetrahydro-l-methoxythiophenium-l-oxidehexafluoroantimonate, the first example of an alkoxysulfoxonium salt (18). 

Parameter Antimony trifluoride Antimony trichloride Antimony tribromide Antimony ttiiodide Antimony pentafluoride Antimony pentachloride... 

Antimony Pentafluoride. Antimony(V) fluoride [7783-70-2], colorless, hygroscopic, viscous Hquid that has SbF units with... 

Antimony pentafluoride may be prepared by fluorination of SbF or by treatment of SbCl with HF. In the latter method the fifth chlorine is removed with difficulty failure to remove the chlorine completely results in contamination of the distilled SbF with Sb(III) (27). 

Antimony pentafluoride is a strong Lewis acid and a good oxidizing and fluorinating agent. Its behavior as a Lewis acid leads to the formation of numerous simple and complex adducts. It reacts vigorously with water to form a clear solution from which antimony pentafluoride dihydrate [65277-49-8], SbF 2H2O, may be isolated. This is probably not a tme hydrate, but may well be better formulated as [H O] [SbF OH]. 

The principal use of antimony pentafluoride is as a fluorinating agent. It readily replaces all chlorines with fluorine in organic compounds, and it fluorinates double bonds and aromatic rings. 

Arsenic pentafluoride (arsenic(V) fluoride), AsF, is a colorless gas that condenses to a yellow Hquid its dielectric constant is 12.8 at 20 °C. It is formed by reaction of a mixture of bromine and antimony pentafluoride with arsenic trifluoride. The molecule is a trigonal bipyramid and is somewhat dissociated as indicated by vapor density measurements. 

Fluorination and iodination reactions are used relatively littie in dye synthesis. Fluorinated species include the trifluoromethyl group, which can be obtained from the trichi oromethyl group by the action of hydrogen fluoride or antimony pentafluoride, and various fluorotria2iQyl and pyrimidyl reactive systems for reactive dyes, eg, Cibacron F dyes. 

Grown Ethers. Ethylene oxide forms cycHc oligomers (crown ethers) in the presence of fluorinated Lewis acids such as boron tritiuoride, phosphoms pentafluoride, or antimony pentafluoride. Hydrogen fluoride is the preferred catalyst (47). The presence of BF , PF , or SbF salts of alkah, alkaline earth, or transition metals directs the oligomerization to the cycHc tetramer, 1,4,7,10-tetraoxacyclododecane [294-93-9] (12-crown-4), pentamer, 1,4,7,10,13-pentaoxacyclopentadecane [33100-27-6] (15-crown-6), andhexamer, 1,4,7,10,13,16-hexaoxacyclooctadecane [17455-13-9]... 

Antlu acite hidustries hic., 217, 218 Antlu aqumones, 17 Antibiotics S.p.A., 180 Antimony, 18 Antimony lactate, 18 Antimony pentachloride, 18 Antimony pentafluoride, 18 Antimony potassium tailrate, 18 Antimony tribromide, 18 Antimony trichloride, 18 Antimony trifluoride, 18 Antimony trioxide, 18 AntimycinA, 19 Antofagasta Pic, 206 ANTU, 19 ANWILS. A., 197 APAChic., 218... 

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