Antimony pentafluoride preparation

Sulphur-Oxygeii-Halogen Compounds.—Chemical analysis of a relatively stable complex of methyl fluoride-antimony pentafluoride, prepared from solution in SO2, showed it to contain bonded SO2. A reinvestigation of the solution of the MeF-SbFs system in SO2 and in SO2CIF revealed that both SO2 and SO2CIF may be O-methylated, giving stable non-exchanging ions (5) and (6). 

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). 

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). 

Tetrakis(trifluoromethyl)dithietane is generated by dimerization of hexa-fluorothioaeetone which is prepared in situ from hexafluoiopropylene with potassium fluoride and sulfur [189] or with sulfur and antimony pentafluoride [190] (equation 27)... 

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). 

As discussed, there are various methods of cation-radical generation. Every individual case needs its own appropriate method. A set of these methods is continuously being supplemented. For example, it was very difficult to prepare the cation-radicals of benzene derivatives with strong acceptor groups. However, some progress has been achieved, thanks to the use of fluorosulfonic acid, sometimes with addition of antimony pentafluoride, and lead dioxide (Rudenko 1994). As known, superacids stabilize cationic intermediates (including cation-radicals) and activate inorganic oxidants. The method mentioned is effective at -78°C. Meanwhile, -78°C is the boundary low temperature because the solution viscosity increases abruptly. This leads to the anisotropy of a sample and a sharp deterioration in the ESR spectrum quality. 

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

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. 

I -(cis-1,2-Dimethylcyclopropyl)ethyl and l-(cw-2,3-dimethylcyclopropyl)ethylcations, 51 and 53, prepared from their corresponding alcohols with antimony pentafluoride (equations 37 and 38), undergo degenerate equilibria even at temperatures as low as -135 °C, indicating that the barriers for their rearrangements are probably less than 5... 

More recently, development of the superacid solvent systems has permitted the preparation at low temperature of stable solutions of carbocations of many structural types. The solvents ordinarily used consist of the strong Lewis acid antimony pentafluoride with or without an added protonic acid, usually hydro-... 

Pure crystalline I2+Sb2F11 has been prepared by the reaction of iodine with antimony pentafluoride in liquid sulfur dioxide as solvent.789 After removal of insoluble SbF3, deep blue crystals of l2+Sb2Fn were obtained from the solution. An X-ray crystallographic structure determination showed the presence of the discrete... 

Typical alkylation reactions are those of propane, isobutane, and n-butane by the ferf-butyl or sw-butyl ion. These systems are somewhat interconvertible by competing hydride transfer and rearrangement of the carbenium ions. The reactions were carried out using alkyl carbenium ion hexafluoroantimonate salts prepared from the corresponding halides and antimony pentafluoride in sulfuryl chloride fluoride solution and treating them in the same solvent with alkanes. The reagents were mixed at —78°C warmed up to — 20°C and quenched with ice water before analysis. The intermolecular hydride transfer between tertiary and secondary carbenium ions and alkanes is generally much faster than the alkylation reaction. Consequently, the alkylation products are also those derived from the new alkanes and carbenium ions formed in the hydride transfer reaction. 

Olah, G. A., Mo, Y. K. Organometallic chemistry. III. Attempted preparation of trivalent silicocations (silicenium ions). The exchange reaction of methylfluorosilanes with antimony pentafluoride. J. Am. Chem. Soc. 93,4942-43 (1971). 

The blue solid prepared by Rulf et al. (9) in 1906 and thought to be (SbF5)aI was probably a mixture of an la fluoroantimonate salt, and some Sb(III)-containing material. Pure crystalline la SbaFu has recently been prepared by the reaction of iodine with antimony pentafluoride in liquid sulfur dioxide as solvent (11). After removal of insoluble SbFg, deep blue crystals of la SbaFi were obtained from the solution. An X-ray crystallographic structure determination showed the presence of the discrete ions la and SbaFu . Crystalline solids that can be formulated as la SbaFu and Ia TaaFii have also been prepared by Kemmitt et al. (4) by the reaction of iodine with antimony or tantalum pentafluorides in iodine pentafluoride solutions. 

The most convenient route to Og salts appears to be the photochemical synthesis of 02 A8F6"(SbPg) from oxygen, fluorine, and arsenic (antimony) pentafluoride 43). Most Og preparations involve the reaction of fluoride ion acceptors with OgFa or O4F2 at low temperatures or with O2 and Fa mixtures under conditions favoring synthesis of the long-lived O2F radical, e.g.. 

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