Transhalogenation


Transhalogenation is a substitution reaction in which a halogen atom of a halogen compound is exchanged for another halogen atom, for example the reaction of an alkyl chloride to an alkyl fluoride by means of sodium fluoride:
R-Cl + NaF → R-F + NaCl
If the halogen compound is an organic compound, this is called Finkelstein reaction. However, it is also possible, for example, to produce phosphorus fluoride compounds by transhalogenating chlorine, bromine or iodine bound to phosphorus with a metal fluoride.

Details and biological use

As a halogen source for transhalogenation, metal halides are often used, but also the use of onium halides is possible. Transhalogenation has been described as a gentle method for the synthesis of fluoroorganylboranes. It is also possible to produce aryliodides from the corresponding aryl chlorides or aryl bromides.
One investigation showed a possibility to perform transhalogenation by means of genetically modified enzymes.

Literature