It is likely that the initial attack of ozone on the olefin is governed by the electron-withdrawing effects of the fluorine atoms. Huisgen has mentioned that the electrophilic attack of ozone as in I can be treated as a 1, 3-dipolar cycloaddition." Hence, he reasoned that chlorinated and fluorinated alkenes are poor 1, 3-dipolarophiles due to a decrease in electron density of the double bond. The present results are consistent with this trend. Perfluoroethylene will not ...