BIMOLECULAR REACTIONS OF THE BETA-DISTONIC ISOMER OF THE ETHANOL RADICAL CATION - CH2CH2OH2+

The first experimental study on the properties of the long-lived, low-energy radical cation .CH2CH2OH2+ is reported. Bimolecular reactions of this ion and its conventional isomer, the radical cation of ethanol have been investigated in a dual-cell Fourier transform ion cyclotron resonance mass spectrometer. Strikingly different reactivity is observed for these two radical cations. The distonic ion undergoes thermoneutral exchange of a water molecule when reacted With H-2- or O-18-labeled water. Acetonitrile readily replaces water in this ion, as well. The ethanol radical cation predominantly reacts by proton transfer with all of these reagents. The same is true for protonated ethanol. Thus, thc chemical properties of the distonic ion do not reflect the ground-state structure, a covalently bound, protonated radical, which is expected to react like protonated ethanol with bases and nucleophiles. The observed reactivity is rationalized on the basis of an electrostatically bound intermediate, in accordance with the description of the distonic ion as a loosely bound ion-dipole complex of ionized ethylene and water.