Carbonium ions short-lived

However, with the advent of the superacid solvents, a multitude of long-lived stable carbonium ions have been made available for extended study. Clearly, then, the door is open to quantum 5ueld determinations, kinetic treatment, studies on the effects of various solvents and sensitizers and quenching experiments (compare the very recent study by Bethell and Clare, 1972). In short, the photochemistry of carbonium ions is still in its infancy and there is a wealth of information yet to be gained. 

It should be remembered, of course, that in the carbonium theory the word ion has a different connotation than it does in inorganic chemistry the degree to which the ester is dissociated may actually lie somewhere between the undissociated ester as in the ester mechanism and the free ions as usually written (although actually believed to be very short-lived) in the carbonium ion mechanism. ... 

The role of "silent" species, in particular, hydrogen atoms, "dark" states, proton adducts, and carbonium ions. How do these species form and interact with each other, excited states, and primary and secondary ions Are there chemically-significant short-lived intermediates, such as carbenes and biradicals or some other unrecognized species ... 

In this book the available data are considered on the rates of 1,2-shifts in terms of the above approach. The rearrangements of long-lived carbonium ions as well as those assumed to involve the formation of short-lived carbonium ions or the like structures will be considered here. 

Hot °, non-solvated and vibrationally excited carbonium ions have also been proposed for the nitrous acid deamination to account for the differences between deaminadon and solvolysis. The carbonium ion from solvolysis is presumably normal by right of primogeniture. The concept of a non-solvated carbonium ion as a little-solvated, high-energy, very short-lived, open carbonium ion is close to our view of the cation in the counter-ion hypothesis. The hotness of a hot ion has not been defined explicitly, but in the sense of hot ions having more energy than ions obtained in solvolyas, the ions in the coimter-ion hypothesis are hot. Attention has previously been drawn to vibrationally excited species, but in the treatment of Corey and coworkers, the vibrational excitation of the cation alone was considered... 

The cationic analog of CHa is CH3+, Such a species, called a CARBON lUM ION, has only a sextet of electrons about the carbon atom and, as expected, reacts readily as a Lewis acid to complete the octet. Car-bonium ions are also formed as very short-lived intermediates during the course of certain organic reactions. Some carbonium ions have been identified in solution under especially favorable conditions. A typical preparation of a carbonium ion is the following electrophilic displacement (page 258) on F by the Lewis acid SbFs as shown ... 

---