FORMATION OF CARBENIUM IONS AND NAKED ANIONS BY THE PROTONATION OF PHTHALOPHENONE WITH A SUPER ACID.

Article abstract of DOI:10.1002/bbpc.19870910710

Two molecules of a strong acid such as CF//3SO//3H are necessary to cleave the lactone ring of phthalophenone. NMR and conductivity measurements reveal that the carboxylate group has to be protonated for this purpose followed by its solvation with an additional molecule of acid. But CF//3SO//3** minus which is simultaneously formed behaves as a naked anion in the solvent dichloromethane. CNDO-calculations indicate a strong interaction between the charged central carbon atom and the COOH group in o-HOOH(C//6H//4)C** plus (C//6H//5)//2 which is accompanied by an unusually large twisting of the phenyl rings.