Carbyl sulphate

Fluorinated alkenes320-323 and many simple alkenes324-327 give / -sultones (equation 70) in reasonable yields, although these sultones are sometimes too unstable to isolate. In the latter case, a carbyl sulphate may be produced328, as exemplified in equation 71. 

Cerfontain and coworkers150,325-327 have shown that both sultone and carbyl sulphate formation are stereospecific reactions. Roberts and coworkers324 have indicated that the reaction is a [2 + 2] cycloaddition process however, some earlier workers have argued that the reaction is a step-wise process321,329. 

Sulphur trioxide is well known for its ability to insert into various bonds as is evident in the formation of cyclic pyrosulphates ( carbyl sulphate ) from /i-sultones26—see Section II.A.l. The mechanism of this and other insertion reactions is uncertain26. 

Regnault found that ethylene combines with the vapour of sulphur trioxide to form a crystalline compound 2114(803)2 which he called acide althionique. Magnus (1839) obtained it by the action of sulphur trioxide on alcohol and called it carbyl sulphate. In contact with water it formed a dibasic acid, C2H4S2O7H2, ethionic acid, and on boiling with water a monobasic acid, C2H4SO4H2, isethionic acid. 

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