Abstract: By use of spin trapping reagents, 2, 3,5,6-four metyl nitrosobenzene and phenyl t-butyl nitrone, in combination with ESR technique, the active free radicals were studied in the photochemical hydrogen abstraction reaction between benzophenone and twelve substituted amides, RC₆H₄NHC(O)CH₃ (R=CH₃, CI, Br, H, NO₂), C₆H₅N(R)C(O)CH₃ or HC(O)NR₂(R=CH₃, C₂H₅). The results show that:(1) for RC₆H₄NHC(O)CH₃,benzophenone abstracts H from nitrogen to form RC₆H₄NC(O)CH₃. (2)for C₆H₅N(R)C(O)CH₃ or HC(O)NR₂,benzophenone adstracts H from the methyl group linked with the carbonyl,from the carbony or from the carbon linked with nitrogen, respectively,to form C₆H₅N(R) C(O)CH₂, C(O)NR₂,C₆H₅N (CHR')C(O) CH₃ or HC(O).

Key words: Benzophenone, Spin trapping, Photochemical abstraction reaction ESR, Free ridical