Perfluoroalkyl hypochlorites

The fluoroalkyl hypochlorites readily react with GO and SO2 to form the corresponding chloroformates and chlorosulfates in near quantitative yields (270). They add to olefins giving a-chloroethers (271). Borate esters are obtained by reaction of perfluoroalkyl hypochlorites with BGl (272). 

The formation of chloroformates and chlorosulphates via insertion of carbon monoxide and sulphur dioxide, respectively, into the O—Cl bonds of per- or poly-fluoroalkyl hypochlorites (sec Vol. 1, p. 150) has formed the subject of some new patent literature. Perfluoroalkyl hypochlorites have also been used to prepare perfluoro-[(iV-chloro)methylethylamine [CjFj NiCFt-f CFa-OCl (CF3)(C F,)NC1 + COF2] (see p. 212), AW-dichloro(chloro-... 

For information on the synthesis of ethers from perfluoroalkyl hypochlorites, and via free-radical additions to fluorinated olefins, see pages 151 and 25, respectively. 

The preparation of the first perfluoroalkyl hypochlorites via caesium fluoride or Lewis acid (HF, BF, or AsFj) catalysed addition of chlorine monofluoride across the 0=0 bond of a perfluorocarbonyl compound, first reported in 1968 and a modification of an excellent general route to perfluoroalkyl hypofluorites employing fluorine and carbonyl compounds, has now been described in detail > the addition proceeds smoothly and in almost quantitative yield at low temperatures, e.g. 

Thermal or photolytic cleavage of the O—Cl bond in a perfluoroalkyl hypochlorite is readily effected, but in general members of this class are much more stable thermally than their hydrocarbon analogues. Trifluoromethyl hypochlorite is the most stable of the series (thermolysis occurs only slowly at 150°C ), rupture of the O—Cl bond becoming easier as the perfluoroalkyl chain lengthens or branches > decomposition occurs in a manner apparently analogous to that of perfluoroalkyl hypofluorites, e.g. 

Oxidation of methyl perfluoroalkyl sulphones with refluxing aqueous potassium permanganate produced the perfluorinated alkanesulphonic acid in 85% yield as the potassium salt (equation 86). On the other hand, attempted oxidation with sodium hypochlorite caused only chlorine substitution (equation 87). Reaction of the new sulphone with aqueous hydroxide gave the same perfluoroalkane sulphonic acid salt (equation 88). 

A series of functionalized alkenes has been subjected to selective epoxidation reactions. Oxidation of perfluorinated vinyl polyethers by bubbling oxygen through the liquid that contains a catalytic amount of a Lewis acid, e.g. antimony(V) fluoride, results in the formation of acid fluorides together with a smaller amount of C = C bond cleavage.76 Perfluorinated pentaaIkyI-2.3-dihydrofuran 38, an example of an unsaturated cyclic ether that is quite stable owing to perfluoroalkylation. is epoxidized by hypochlorite to the product 39 at 45 C.62... 

Other sulfonate derivatives are obtained by the use of trifluoromethanesulfonyl hypochlorite and hypobromite (CF3S020C1 and CF3S020Br) in reactions with perfluoroalkyl halides and their derivatives [30]. These reactions lead to the corresponding trifluoromethanesulfonate derivatives of alkanes (equation 28) (Table 11). The reaction proceeds with complete retention of stereochemistry at the carbon center [30]. 

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