Rearrangement and fragmentation of estrogen ether ions: new aspects found with Fourier transform ion cyclotron resonance mass spectrometry

Subsequent radical fragmentation reactions of N, N-diethylamino-substituted azobenzene derivatives in a Fourier transform ion cyclotron resonance mass spectrometer using collision-induced dissociation and photodissociation

The fragmentation behavior of N, N-diethylamino-substituted azobenzene derivatives is investigated by high-resolving mass spectrometry using a Fourier transform ion cyclotron resonance mass spectrometer. Former investigations by photodissociation as well as collision-induced dissociation experiments used to induce a loss of C₃H₈ from the diethylamino group. The position of the additional proton in [M + H]⁺ ions is important due to the sequences of radical fragmentation reactions. Two possibilities arise. First, a charge is located at the azo group leading to a methyl radical loss. The second possibility is that the charge has been located on the aniline nitrogen of the molecule resulting in an ethyl radical loss. Only o-ethyl red has shown the overall loss of C₃H₈ in a two-step radical reaction mechanism. Nevertheless, p-ethyl red and ethyl yellow have shown systematic fragmentation reactions as well. Loss of C₃H₈ has not been likely regarding both these molecules. All experimental findings together with quantum chemical calculations as well as kinetic calculations support the proposed fragmentation mechanisms of the three azo dyes.

Fragmentation of xanthene dyes by laser activation and collision-induced dissociation on a high-resolution Fourier transform ion cyclotron resonance mass spectrometer

Surprising fragmentation reactions in different xanthene dyes have been investigated by means of photodissociation and collision-induced dissociation in a 9.4 T FT-ICR mass spectrometer. It is shown that extensive rearrangement reactions lead to the formation of unexpected fragments which are identified for the first time by the use of high resolving mass power. The observed reactions are an example of the fragmentation of a quinoidal even-electron cation.