Acetyl cation superelectrophilic

As noted previously in Chapter 1, the electrophilic reactivities of acetyl salts increase dramatically as the acidity of the reaction medium increases. This was one of the observations that lead Olah and co-workers to first propose the concept of superelectrophilic activation, or protosolvation of the acetyl cation, in 1975.2 This seminal paper described the chemistry of acetyl hexafluoroantimonate (CHsCO+SbFg-) and the reaction with alkanes in various solvents. In aprotic solvents such as SO2, SO2CIF, AsF3, and CH2CI2, there was no reaction. However in HF-BF3, acetyl salts react with Ao-alkanes and efficient hydride abstraction is observed.27 This was interpreted by Olah as evidence for protonation of the acetyl... 

There are several reports of activation of acyl cations by superacids, suggesting the involvement of gitonic superelectrophiles.61 As discussed in Chapter 2, hydride transfer from isobutane to the acetyl cation has been reported when the reaction is carried out in excess HF-BF3. At the same... 

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