Electron impact and chemical ionization mass spectra of aryl ureas

Abstract The electron impact and chemical ionization mass spectra of a series of N ,N′, ‐diaryl ureas have been compared. The electron impact mass spectra indicate rearrangements leading to two pairs of aromatic amines and isocyanates, either as ions or molecules. The chemical ionization mass spectra showed the formation of protonated amines and isocyanates via rearrangement.