Mass spectra of N and O methyl and methylthiomethyl derivatives of benzophenone oxime

The mass spectra of benzophenone oxime O-methyl and O-methylthiomethyl ethers, α,α-diphenyl-N-methyl and methylthiomethyl nitrones, and some deuterated analogues, are reported. Fragmentation pathways are discussed, with particular reference to the structures of ion m/e 211 found in all the spectra. Some evidence suggests nitrone → O-ether rearrangement at either neutral molecule or molecular ion level.