Mass spectral fragmentation pattern of 3‐methyl‐4‐arylaminomethyleneisoxazol‐5‐ones

Abstract The mass spectral fragmentation patterns of 3‐methyl‐4‐arylaminomethyleneisoxazol‐5‐ones obtained by electron impact have been elucidated. The base peaks are due to the molecular ions. The main fragmentation routes involve loss of H, OH, H2O, CO2 and COOH from the molecular ions as well as rupture of the exocyclic CH‐NH bond.