Mass spectra of substituted Δ2-1,2,4-oxadiazolines—I

The electron impact fragmentation of four Δ²-1,2,4-oxadiazolines with substituents at positions 3 and 5 has been examined. The direct analysis of daughter ions and high resolution mass measurements provided valuable information regarding certain ions. The present study clearly demonstrates that the substitution of phenyl or a substituted phenyl group for alkyl at C-3 and alkyl in place of a phenyl substituent at C-5 in the oxadiazoline system alters the fragmentation modes considerably.