Chlorination of propene at 773 K
The reaction proceeds via a SFR (Substitution Free Radical) mechanism and yields an allylic or benzylic halogenated alkene. This result is specific for low concentration of halogen and high temperature.

The results of the same reaction of halogens with alkenes but at different reaction conditions, i.e. high halogen concentration and room temperature result into anti addition of the halogen atoms on the double bond. Thus the reaction takes place faster in presence of $\ce{CCl4}$, i.e. non polar solvents. The reaction proceeds via formation of cyclic intermediate. The result of the same reaction in water instead of $\ce{CCl4}$ will result in to anti addition of halide ion and $\ce{OH-}$ ion on the double bond.