Antimony pentafluoride, and

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. 

C. The Fluorosvlphonic Acid-Antimony Pentafluoride and Hydrogen Fluoride-Antimony Pentafluoride Solvent Systems Attempts to generate simple alkyl-, arylalkyl-, and cycloalkyl-carbonium ions in sulphuric acid or oleum solution generally result in... 

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. 

Metal Halides. Phosphorus ignites in contact with antimony pentafluoride and explodes with chromyl chloride when moist.17... 

SbCla is a relatively weak Lewis acid, since in the presence of a mixture of mesity-lene and benzoyl chloride it gives a complex with mesitylene Antimony penta-chloride is stronger and gives a 1 1 complex with perylene whose electronic spectrum is similar to that of the perylene cation Complexation has been claimed between antimony pentafluoride and aromatic olefins such as 1,1-diphenylethylene and stilbene ... 

Caution. All reactions should be conducted In a well-ventilated fume hood with appropriate precautions. Arsenic and antimony pentafluoride and arsenic trifluoride are very poisonous and hydrolyze readily to form Bromine is corrosive and is harmful to the skin and mucous membranes. Sulfur dioxide is poisonous and can generate 3 to 4 atmospheres pressure at room temperature. Well-constructed glass vessels or metal systems must be employed to prevent pressure bursts. The use of rubber gloves, safety glasses, and face shields is recommended. 

Freon solution of freshly distilled antimony pentafluoride, and after stirring for 1 hr. the white, crystalline precipitate is collected, washed with cold Freon 113, and dried in vacuum. 

Superacids such as Magic acid (42), a system containing antimony pentafluoride and fluorosulfonic acid and designated a superacid because it is a more ready electron pair acceptor than anhydrous aluminium chloride (43), have useful catalytic properties in synthetic organic chemistry where the reaction involves a carbocation intermediate. The extremely low nucleophilicity of the counter ion of such acids make it possible to prepare cations such as the tertiary butyl (( 3)30" " with an appreciably long life time in superacid solutions whereas such cations are too reactive... 

Electrochemical oxidation of biphenylene and a tetramethyl derivative have been shown to produce dications which have greater stability than the dication from biphenyl [185], Biphenylene and methyl derivatives have been converted into dications by the action of a mixture of antimony pentafluoride and sulphonyl chloride fluoride [186], Their H- and C-n,m.r, spectra indicate that these dications have delocalised lO-ir-electron systems [186],... 

Dis.solution of 1,4-dimethyl-, 1,3,5,7-tetramethyl, 1,3,5,7-tetra-phenyl- or S /m.-dibenzo-cyclooctatetraenes in a mixture of antimony pentafluoride and sulphonyl chloride fluoride at -78 results in the formation of species which, judged from their n.m.r. spectra, are planar dications with delocalised sets of six ir-electrons, giving rise to diamagnetic ring currents [59]. In the case of the dibenzo--derivative it appears that all fourteen ir-electrons are delocalised over the sixteen carbon atom periphery. 

Next, let s consider cyclopropene. Two of its carbon atoms are sp hybridized. However, one is sp hybridized and it is not aromatic. However, as in the examples we considered above, it can be converted to an aromatic ion. Cyclopropene can be converted to the cyclopropenium cation by treating it with the very potent acid mixture consisting of flurosulfuric acid, antimony pentafluoride, and sulfur dioxide. This mixture is sometime called magic acid because of its ability to produce stable solutions of carbocations. 

From these computations and related work, it has been established quantitatively that antimony pentafluoride and its oligomers are benchmarks for molecular, strong Lewis acids. 

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