The [CH2CHOH.+, CH3CHO] solvated enol radical cation

The bimolecular reaction of the CH2CHOH.+ enol ion (m/z 44) with acetaldehy de gives a strongly dominant product, m/z 45, formed mainly by proton trans fer from the ion to the molecule. The abundance of the product coming from a H-. abstraction reaction from the neutral, albeit more exothermic, is neg ligible. In order to explain this result, the long lived [CH2CHOH.+, CH3CHO ] solvated ion was generated by reaction of the CH2CHOH.+ enol ion with (CH 3CHO)(n), in the cell of a Fourier transform ion cyclotron resonance mass s pectrometer. The structure of this solvated ion was clearly established. La beling indicates that [CH2CHOH.+, CH3CHO], upon low energy collisions, reac ts by H-. abstraction more rapidly than by H+ transfer to the neutral moiet y. This shows that the entropic factors are determinant when the enol ion r eacts directly with acetaldehyde. (J Am Soc Mass Spectrom 2000, 11, 705-710 ) (C) 2000 American Society for Mass Spectrometry.