Electron impact and field desorption mass spectrometry of some macrocyclic‐acyclic polyether‐ester compounds

The electron impact mass spectrometric behaviour of a series of macrocyclic‐acyclic polyether‐ester compounds containing an isoxazole, benzene or pyridine ring is discussed in detail with the aid of exact mass measurements and metastable ions (linked scans B/E and B2/E). The nature of unusual [M+H]+ species, present in the crown moieties only, is elucidated by means of low electron energy measurements and labelling experiments. The field desorption spectra show only intense peaks corresponding to [M+H]+ species and rule out the presence of dimeric moieties.