CHEMISTRY OF ORGANO HALOGENIC MOLECULES. PART XCIV. THE EFFECT OF FLUORINE ON PHOTOCHEMICAL CARBON-HALOGEN BOND CLEAVAGE IN Z AND E-1-FLUORO-2-HALO-1,2-DIPHENYLETHYLENES

Article abstract of DOI:10.1016/S0022-1139(00)81541-9

Irradiation of Z and E-1-fluoro-2-halo-1,2-diphenylethylenes at λ=253.7 nm gave Z and E-2-fluoro-1,2-diphenylethylene and 1,2-diphenylacetylene.The phototransformation depended on the geometry of the molecule, the halogen atom present, and the solvent used.Introduction of fluorine on the olefinic carbon atom in the β-position to a carbon-halogen bond increased the photocleavage compared to the unsubstituted substrate, and reduced the electron transfer from the caged radical-pair to cationic intermediates.Increased solvent polarity resulted in enhanced photocleavage of the carbon-halogen bond.