The introduction of fluorine atoms in an organic molecule deeply affects all its physical properties (boiling and melting points, viscosity, dipole moment, etc.), chemical properties (conformation, reactivity, etc.) and biological effects (action mode, bio-availability, etc.), due to its very specific characteristics (van der Waals radius between hydrogen and oxygen radii, very strong electronegativity, propensity to form strong bonds with carbon, hydrogen or silicon, hydrophobic behavior). These modifications explain the importance of fluorinated organic compounds in numerous domains: biologically active compounds (drugs, soil chemistry, medical imaging), polymer materials (Teflon^®, PVDF, membranes for energy storage or production (Nafion^®), surfactants for textile manufacture and fire extinguishers, caloric transporters or unusual reaction mediums (fluorous phases).

Ozone hole above Antartic

However, due to the particular properties of fluorine and its influence on the reactivity of fluorinated molecules, the chemistry of fluorine cannot be compared to its halogenated homologues. Technically, the very high reactivity of fluorine F2 and the aggressiveness of anhydrous and aqueous fluoric acid towards common materials require specific devices and reaction vessels. On a chemical point of view, the introduction of fluorine atoms or fluorinated groups (CF₃, CHF₂, OCF₃, SCF₃, CF₃CO, CnF_2n+1,...) to an organic substrate implies that specific methods must be devised for the design of the reactants and for the reactions which must be achieved. Similarly, the functionalization of fluorinated compounds frequently requires more or less important modifications of “classical” reactions. Only one natural stable fluorine isotope exists, the ¹⁹F isotope. One artificial radioactive isotope (¹⁸F), with a short half-life (t_1/2 = 110 min), is now routinely produced; it is used to label bioactive molecules for medical imaging using PET (Positron Emission Tomography).