Abstract: A Study on the Electron Impact Mass Spectra of 2Phenyl3Alkyl7Nitro1,4Benzoxathiin4,4DioxidesAuthor Cao Song(Institute of Pesticides & Pharmaceuticals,East China University of Science & Technology,Shanghai 200237,China)Received 19980512 Abstract The electron impact mass spectra of eight 2phenyl3alkyl7nitro1,4benzoxathiin4,4dioxides(18)were reported.A possible fragmentation mechanism for these compounds was proposed.Key Words: 2phenyl3alky17alky17nitro1,4benzoxathiin4,4dioxides,electron impact mass spectra,mechanism