Potassium fluoride reacts in triethyleneglycol (TEG) on β-fluoro-γ,δ-unsaturated p-toluenesulfonates to give 2-fluoroalka-1,3-dienes (HOTs elimination) and the corresponding difluoroolefins (substitution of O-tosyl group by fluorine). S N E competition may be related to the structure of the starting tosylate. However, the exclusive formation of conjugated 2-fluoroalkadienes may be realized by using DBU at room temperature instead of KF.