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Ab initio molecular orbital and density functional theory (DFT) calculations were performed to investigate energies, geometries, and reactivities of halomethyl cations and their protonated analogues. On the basis of calculated energies the observed superelectrophilic activation of the halomethyl cations in superacid solutions is discussed. The protonated halomethyl cations have considerable kinetic and thermodynamic stability. 13C NMR chemical shifts of selected systems were calculated by IGLO method and compared with experimental data.

Table 1.G-VALUES OF o-NITROPHENOL (o-nPh) FORMATION AND DECOM-POSITION IN SOLUTIONS OF 1•0 M SOlJlU!d NITRATE Composition of solu Lion G*(o-nPh) G*(o-nPh) (formation) (decomposition 20 mM benzene (approx.) :J-3 mM phenol, 0•05 N H,So, 3•3 mllf phenol, 0•G N NaOH 0•41 0•08 0•38 * Molecules transforn1cd for 100 cVofabsorbed energy. 0•09 0•13these ions, or of any other known nitrating agents, is improbable, though in the last case increase of the amount of the o-nitrophenol formed may be due to the action of nitric acid on the phenol molecules. It is well known (see, for example, ref. 4) that such a reaction is catalysed even by the traces of HNO,, which are present here due to the radiation-induced reduction of NO;;-ions to NO::;ions.The yields of o-nitrophenol in the neutral solution of benzene and the alkaline solution of phenol are approximately equal, as are the yields of the decay in both phenol solutions. The decay of o-nitrophenol, or the decrease of the yield observed during the prolonged irradiation, may be due to the oxidation and/or further nitration of this compound.The data obtained in this work, together with those published previously, do not allow us as yet to propose any definite mechanism of the radiation-induced nitration. It seems probable, however, that this process may proceed simultaneously by oxidation of the primarily formed nitroso-compormds as well as by a direct radical reaction.

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