Alkoxy-and Hydroxylated Carbocations

Taft and Ramsey156 used NMR spectroscopy to investigate the nature of a series of secondary and tertiary carboxonium ions. 

With Bollinger157 we obtained primary carboxonium ions such as methoxy- and phenoxymethyl cations and their halogenated derivatives 

Acidic oxonium ions can be readily obtained and studied in superacidic media. With Sommer and Namanworth43 we showed that primary and secondary alcohols are protonated in FS03H— SbFs(S02, S02C1F) solution at —60 °, giving well-re-solved spectra of the alkyloxonium ions. 

At higher temperature they cleave to alkyl cations the kinetics of these cleavage reactions could be followed by NMR spectroscopy. 

Tertiary alcohols (with the exception of the ones containing strong electron withdrawing groups, such as CF3) generally dehydrate very fast in the acid media, and the intermediate protonated species cannot be observed, even at low temperatures before cleavage. 

---