Fluorosulfonic acid, reaction

The stmcture of the ketones produced from unsymmetrical internal perfluoroepoxides has been reported (5). The epoxide ring may also be opened by strong protic acids such as fluorosulfonic acid or hydrogen fluoride at elevated temperatures (23—25). The ring opening of HFPO by sulfur trioxide at 150°C has been interpreted as an example of an electrophilic reaction (26) (eq. 3). 

Arsenic trifluoride (arsenic(III) fluoride), AsF, can be prepared by reaction of arsenic trioxide with a mixture of sulfuric acid and calcium fluoride or even better with fluorosulfonic acid. Chlorine reacts with ice-cold arsenic trifluoride to produce a hygroscopic soHd compound, arsenic dichloride trifluoride [14933-43-8] ASCI2F35 consisting of AsQ. and AsF ions (21). Arsenic trifluoride forms a stable adduct, 2AsF2 SSO, with sulfur trioxide and reacts with nitrosyl fluoride to give nitrosonium hexafluoroarsenate(V) [18535-07-4] [NO][AsFg]. 

Acids are poor catalysts for ring cleavage of thiirane 1,1-dioxides but are good catalysts for reactions of thiirane 1-oxides with nucleophiles. These reactions of episulfoxides are believed to proceed by protonation of the oxygen atom (but see the NMR evidence cited above for 5-protonation in fluorosulfonic acid) and will be treated in the section on nucleophilic reactions. 

The monofluoromethylene group and difluoromethyl group m 1H perfluoro-alkanes and -cycloalkanes are oxidized at the C-H bond to perfluoroalkyl and perfluorocycloalkyl fluorosulfates by anodic oxidation m fluorosulfonic acid [J, 4] Two modifications of the method are used ox idation by fluorosulfonyl peroxide generated pnor to the reaction [J] (equation 2A) and direct electrolysis m the acid [i, 4] (equabons 2B and 3)... 

Hexafluoropropene is converted to its 1,2-epoxide in 55% yield by bubbling through a solution of chromium tnoxide in fluorosulfonic acid [8], the analogous reaction with a mixture of chromium trioxide and dichromium tnoxide gives pentafluoroacetonyl fluorosulfate [.5] (equation 6)... 

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). 

Octafluoroisobtttylene, whose double bond has reduced electron density and limited accessibility, reacts with sulfur tnoxidg under vigorous conditions The reaction mixture contains various components including bis-oi-tnfluorometh-yldifluoroethane-P-sultone, bis(a-trifluoromethyldifluoroethane)-(i-pyrosultone, the heptafluoroisobutenyl ester of fluorosulfonic acid, and the heptafluoroiso-butenyl ester of fluoropyrosulfomc acid [73] (equation 4)... 

The lack of any difference in the rate of isomerization between fluoro-sulfonic acid solutions of 34 which had been thoroughly degassed, and those which were saturated with oxygen, suggests that the reaction does not proceed via a triplet mechanism. In fluorosulfonic acid no unproton-ated acid is detected, ruling out the possibility of n,7r excitation. Thus, there is little doubt in this case that it is the Tr,Tr singlet state which is the reactive species. Experiments carried out with a variety of methyl-substituted protonated cydohexadienones have likewise ruled out the... 

Fluorosulfonic acid can be used in fluorination reactions, and it functions as a catalyst in reactions such as alkylation and polymerization. One of the most important uses of FS03H and C1S03H is as sulfonating agents to introduce the -S03H group into various organic materials. 

Reaction Scheme I. Polymerization of THE with esters of fluorosulfonic acids... 

The highest yield of perchloryl fluoride (97%) was achieved with a mixture of fluorosulfonic acid and SbFj as fluorinating medium. Potassium, sodium, lithium, magnesium, barium, calcium, and silver perchlorates and perchloric acid itself undergo the reaction. Commercial reagents are used and their additional puriflcation is not necessary unlike all the previous methods the preparation of perchloryl fluoride by this method can be carried out at room temperature. At high temperature (100°-135°C) the reaction time is 1-10 min in all, which allows the process to be carried out continuously in a packed column. The purity of product obtained after the usual puriflcation reaches 98% and over air and carbon dioxide are present as trace impurities 23). 

Many synthetic processes have been described for acesulfame. One involves the condensation of a halosulfonyl isocyanate and an acetylene or a ketone (67,68). The fluorosulfonyl isocyanate can be prepared by reaction of sulfuryl diisocyanate with fluorosulfonic acid (69). 

Symmetrical iodonium salts. Arenes, including non-activated compounds such as nitrobenzene, react with the powerful electrophile iodosyl fluorosulfate (FS020I0, obtained from iodine, iodine pentoxide and fluorosulfonic acid) to give directly diaryliodonium hydro sulfates. The reaction is performed at low temperature (Scheme 32) [97]. 

Superacidic FSO3H (fluorosulfonic acid, Ho — 15) has also been used in some studies involving superelectrophilic activation. However, due to its tendency for sulfonation and oxidation, this acid has found only limited use in synthetic conversions involving superelectrophiles. Fluorosulfonic acid has been shown effective to activate nitronium salts in their reactions with weak nucleophiles, and again it was suggested that the protosolvated species (6) is involved in the reactions.28 Both fluorosulfonic acid and triflic acid have been reported to give the diprotonated species (14) from 3-arylindenones (eq 12) 29... 

The characteristics of the electrooxidation of fluorosulfate anions in the electrolysis of a potassium fluorosulfate solution in fluorosulfonic acid have been investigated. The formation of oxide layers on platinum and the modification of glassy carbon with fluorosulfate groups during anodic polarization in fluorosulfonic acid are studied. The reactions of fiuoroolefin fluorosulfation are considered and a mechanism is suggested223. Trifluoromethylation of carbonyl compounds can be achieved using bromo-trifluoromethane and a sacrificial electrode in solvents such as DMF/pyridine, and DMF/TMEDA, as seen in equation 126224. 

These compounds are not stable in aqueous media, each hydrolyzing to the parent acid and the appropriate hydrogen halide. There are two exceptions the first is NO2CI which hydrolyzes in a different manner (p, 245). The second, and more important, is perchloryl fluoride, C103F, which, under the usual laboratory conditions, is inert to moisture. This remarkable substance, which did not exist a decade ago, is now prepared in ton quantities it is an extremely powerful oxidizing agent at high temperature and has become important in propulsion. It is prepared by the reaction of perchlorates with fluorosulfonic acid ... 

Fluorosulfonic acid is a fluorinating agent, and it also functions as an acid catalyst for alkylation, polymerization, and other reactions. Finally, both HSO3F and HSO3CI are... 

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