Abstract: The active radicals produced in the photochemical hydrogen abstraction reactions between benzophenone and 2-ary1-1, 3-dithiolan were studied by combination of spin trapping technique with ESR specroscopy. Results show that the homolytic cleavage of C-H on the 2-C (or 4-C, 6-C) could take place, the produced active radicals  CH₂ werestabilized by the conjugation of adjacent sulphur atoms and could be trapped by nitrosodurene (ND) (or 2,4,6-tri-t-butylnitrosobenzene(TBN)) to form two spin adducts the concentration ratio of which was about 1:1.

Key words: Spin trapping technique, 2-aryl-1,3-dithiolan, Radical, Photochemical hydrogen abstraction reaction, ESR