Arenium ions stable solutions

In Chapter 3, it was mentioned that positive ions can form addition complexes with 7T systems. Since the initial step of electrophilic substitution involves attack by a positive ion on an aromatic ring, it has been suggested that such a complex, called a % complex (represented as 10), is formed first and then is converted to the arenium ion 11. Stable solutions of arenium ions or 7t complexes (e.g., with Br2, l2> picric... 

On the whole these data testify that in many cases the change of the medium affects comparatively little the physical characteristics, relative reactivity and relative stability of the stable carbocations. Hence, the sensitivity of the PMR and NMR- C spectra of arenium ions to the medium effects is small the positions of absorption bands of carbocations including the mesitylenium ion for solutions in acids and for the gas phase are surprisingly close and the influence of the solvent on the kinetic data on the degenerate rearrangements of arenium ions by 1,2-shifts of CHj groups is not appreciable (see Sect. IV.2.B). 

The addition of a nucleophile is also predominant when quenching acid solutions of stable polyfluorinated arenium ions. Careful pouring into a frozen mixture of HCl with CH3OH effects the addition of Q When add solutions are... 

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