Reactivity and Stabilization of Tertiary Alkyl Cations

In previous studies (Hogeveen, 1970) the reactivity of long-lived carbonium ions towards molecular hydrogen has been investigated and interesting differences between secondary and tertiary alkyl cations have been observed. Tliis reaction is too slow, however, to be extended to other types of carbonium ions. The reactivity of carbonium ions towards carbon monoxide is much higher (about six powers of ten) than towards molecular hydrogen, which enabled us to determine not only the rate of reaction (3) for some tertiary and secondary alkyl cations, but also the rate of carbonylation of more stabilized carbonium ions. 

The experimental data for the carbonylation and decarbonylation have been obtained in super-acidic solutions with one or more of the following three techniques  

The reaction of t-butyl cation with carbon monoxide was foimd to be very much faster than that with hydrogen. Both this carbonylation and 

The observed line-broadening behaviour of the signals of the t-C4H ion (at 3-95 p.p.m.) and of the t-C4H9CO+ ion (at 2-07 p.p.m.) is due to the ftimoZecttZar-TiiowowioZectdor Koch equilibrium (6) and not to the conceivable Mnu)lecular-bimdleciilar exchange equilibrium (7)  

The rate constant of formation of isopropyloxocarbonium ions (irreversible at low temperatures, Section III, A) at — 70°C was found to be 3 9 X 10 seo.  

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II. Reactivity and Stabilization of Tertiary Alkyl Cations in. Reactivity and Stabilization of Secondary Alkyl Cations. ... 

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