Electron-impact mass spectra of saturated crown compounds

The electron-impact mass spectra of saturated dicyclohexyl-18-crown-6 were studied, and their fragmentation patterns were compared with those of unsat urated dibenzo-18-crown-6 analogs. Elimination of C2H4O from the molecular ion of dicyclohexyl-18-crown-6 is characterized by a low probability. Succe ssive elimination of C2H4O groups, which is typical of dibenzo-18-crown-6, does not occur at all. A high-energy rearrangement of the [M-18](+) ion is observed, which gives rise to formation of a double bond in the cyclohexane ring. Substituents in the cyclohexane rings affect deeper stages of the fr agmentation process, leading to appearance of characteristic fragment ions.