Antimony pentafluoride reactions

Arsenic pentafluoride (2.08 g., 0.012 mole) is condensed onto powdered sulfur (1.047 g., 0.033 mole) and frozen sulfur dioxide at — 196°, and the reaction vessel is heat-sealed at C and D. The mixture is allowed to warm to room temperature. The solution immediately develops a red color owing to (S16)2 +, just as in the case of the antimony pentafluoride reaction, but on stirring for 1 hour a blue solution is obtained. The reaction is complete within 3 hours. The S02-soluble S8(AsF6)2 is extracted until the solution in A is colorless and there is no residue (five extractions are normally sufficient). As described in the general procedure, flask B is heat-sealed at F while keeping A at liquid N2 temperature. The powdered product obtained from B is further dried to give a yield of 90 % or better. In the typical experiment described 2.48 g. (0.0039 mole) was obtained a 96% yield based on sulfur. Anal. Calcd. for S8As2F12 S, 40.43 As, 23.62 F, 35.94. Found S, 40.53 As, 23.63 F, 36.12. 

Hydrogen fluoride/antimony pentafluoride Reaction in superacidic medium Isocyclic ring closure with dearomatization of phenolethers... 

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). 

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. 

Nitronium fluorosulfate in fluorosulfonic acid adds electrophilically across the double bond offluoroolefins in a nonspecific manner. Tnfluorochloroethylene reacts accordingly with nitronium fluorosulfate to give a 2.1 mixture of regio-isomers [7] (equation 7). Under these reaction conditions perfluoropropylene is unreactive even after extended heating at 80 C 2-Nitroperfluoropropyl fluorosulfate is obtained on treatment of the perfluoropropylene with nitronium fluorosulfate in antimony pentafluoride [5] (equation 8). 

Vinyl and phenyl mfluoromethyl groups are reactive in the presence of aluminum chloride [10] Replacement of fluorine by chlorine often occurs Polyfluori-nated trifluoromethylbenzenes form reactive a,a-difluorobenzyl cations in antimony pentafluoride [11] 1 Phenylperfluoropropene cyclizes in aluminum chloride to afford 1,1,3-trichloro 2 fluoroindene [10] (equation 10) The reaction IS hypothesized to proceed via an allylic carbocation, whose fluoride atoms undergo halogen exchange... 

The reactions of some fluorinated ethers may result in the elimination of alkyl fluorides In the case of 2-methoxyperfluoro-2-butene, treatment with antimony pentafluoride gives perfluoro-3-buten-2-one and methylfluoride [107] By reacting 2-chloro-l,l,2-trifluorodiethyl ether with boron trifluoride etherate or with aluminum chloride, chlorofluoroacetyl fluoride can be obtained with the elimination of ethyl fluonde [108] (equations 76 and 77)... 

Isomerization of fluoroolefins by a shift of a double bond is catalyzed by halide 10ns [7] The presence of crown ether makes this reaction more efficient [74] Prolonged reaction time favors the rearranged product with an internal double bond (equations 3-5) Isomerization of perfluoro-l-pentene with cesium fluoride yields perfluoro-2-pentenes in a Z ratio of 1 6 [75] Antimony pentafluoride also causes isomenzation of olefins leading to more substituted products [76]... 

Fluonnation and skeletal transformation of fluorinated cycloalkanes occurs in the reaction with antimony pentafluoride at high temperature [777] In the case of perfluorinated benzocyclobutanes, an unexpected alicyclic ring cleavage has been observed Perfluorinated alkyl benzocyclobutanes, when treated with antimony pentafluoride, ean be converted to perfluorinated styrenes and then transformed to perfluorinated indans [77S, 779]... 

Few 1-benzothiophene-S-oxides 218 were obtained in moderate yields by treatment of 1-arylacetylenes 219 with sulfur dioxide and benzene in the presence of antimony pentafluoride (equation 127). A series of cyclic sulphoxides have been prepared by hydrolysis of the corresponding alkoxy sulphonium salts 220 " (equation 128). Syn-sulphoxide 221 was obtained in a low yield (15-20%) in the reaction of the dianion of cyclooctatetraene 222 with thionyl chloride (equation 129). 

Reactions of organoxenonium salts [RXe][EFn+)] with Lewis acids do not result in transformation of the organo group of the cation [RXe]+ (6), but rather give rise to fluoride abstraction from the counteranion [EFn+i]. For example, organoxenonium fluoroborates were converted into [EF6]" salts by using arsenic or antimony pentafluoride or their adducts, EFj L (eqs 9, 10) (22, 30). 

In earlier days it was fairly common to suggest that sulfenium ions, RS+, were involved as intermediates in a number of these substitutions, particularly those in which sulfenyl halides RSX reacted with very weak nucleophiles, or those where electrophilic catalysis of the substitution was observed (Parker and Kharasch, 1959). However, it has since become evident (Owsley and Helmkamp, 1967 Helmkamp et al., 1968 Capozzi et al., 1975) that sulfenium ions are almost impossible to generate as intermediates. For example, Capozzi et al., (1975) showed that although treatment of a sulfenyl chloride RSC1 with the powerful Lewis acid antimony pentafluoride led to the complete conversion of the sulfenyl chloride to a cation, what was formed was, not the sulfenium ion RS+, but rather the cation [59] in reaction (172). These results, and others... 

Exchange studies were carried out by solvolysing a series of butyl chlorides in 2m solutions of antimony pentafluoride in fluoro-sulfonic acid at —50° and —78°. The acid contained tracer levels of TjO and small amounts of water to provide sufficient nucleophiles to catalyse proton exchange reactions with some of the intermediates formed in the butyl system (Kramer, 1970, 1973). 

Inductive effects can have very pronounced effects on the reactivity of amides and similar substrates towards nitrolysis. Chemists at the Naval Air Warfare Center (NAWC) have reported an extreme case encountered during the synthesis of the energetic 1,5-diazocine known as HNFX (86). A key step in this synthesis involves a very difficult nitrolysis of the electron deficient N-nosyl (4-nitrobenzenesulfonyl) bonds of (85). Nitrolysis with strong mixed acid requires a temperature of 70 °C for 6 weeks to achieve a yield of 16 %. The same reaction with nitric acid-triflic acid requires a temperature of 55 °C for 40 hours to achieve a 65 % yield of HNFX. The same chemists reported a similar case of N-nosyl bond nitrolysis which needed a nitrating agent composed of nitric acid-triflic acid-antimony pentafluoride. ... 

If, however, the reaction is run in the presence of a Lewis acid, particularly antimony pentafluoride, the reaction takes a different course, giving a diacyl cyclopropane. 

Antimony pentafluoride is prepared by the reaction of antimony pentachlo-ride with anhydrous hydrogen fluoride ... 

Antimony pentafluoride (4.94 g, 22.8 mmole) is added, in a good dry box, to side B of the reaction flask using an all-glass syringe. Elemental mercury (2.74 g, 13.7 mmole) is added to side A. The reaction vessel is fitted at E and F with Nupro or similar metal valves, removed from the dry box, and attached to a vacuum line that has been thoroughly flamed before use. Approximately 10 mL of sulfur dioxide is transferred to side B by cooling with liquid N2, and the... 

Above 175° C, poly(thiocarbonyl fluoride) decomposes (63) to regenerate thiocarbonyl fluoride monomer. Chains capped with CF3 are stable to 300° C when heated in nitrogen, though they decompose at 200° C or below when heated in air. Chains so capped have been made by reaction of the polymer with antimony pentafluoride. 

The triatomic cations are usually prepared from the corresponding interhalogen, by reaction with a halogen acceptor molecule. This is impossible for some of the more exotic species which have no interhalogen precursor. For example, the [Br3]+ cation has been characterized20 in [Br3]+[AsF6], formed from the interaction of arsenic pentafluoride and a bromine/bromine pentafluoride mixture and the [Cl FJ cation results from the interaction of antimony pentafluoride with chlorine monofluoride.21... 

Arsenic Pentafluoride, AsFs, may be prepared by the interaction of arsenic and fluorine in a platinum vessel,2 or by the action of bromine and antimony pentafluoride on arsenic trifluoride.3 The reagents should be dry, and if the reaction in the second case is carried out in a glass vessel, the apparatus should be in one piece and well dried. The bromine is added to the mixture of fluorides at - 20° C. and, after cooling in liquid air, the arsenic pentafluoride is obtained by heating on a water-bath at 55° C., the gas passing through a reflux condenser to a receiver surrounded by liquid air. The product contains bromine, which is removed by passing the gas over molten sulphur. 

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