Transhalogenation is a

substitution reaction A substitution reaction (also known as single displacement reaction or single substitution reaction) is a chemical reaction during which one functional group in a chemical compound is replaced by another functional group. Substitution reactions ar ...

in which the

halide In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a fl ...

of a halide compound is exchanged for another halide.

Finkelstein reaction

A common method is halide metathesis. An example is the conversion of alkyl chloride into alkyl fluoride: :C₃H₅-Cl + NaF → R-F + NaCl This kind of reaction 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 Metal halides are compounds between metals and halogens. Some, such as sodium chloride are Ionic compound, ionic, while others are covalently bonded. A few metal halides are discrete molecules, such as uranium hexafluoride, but most adopt polymeric ...

(such as

sodium fluoride Sodium fluoride (NaF) is an inorganic compound with the formula . It is a colorless or white solid that is readily soluble in water. It is used in trace amounts in the fluoridation of drinking water to prevent tooth decay, and in toothpastes ...

lithium fluoride Lithium fluoride is an inorganic compound with the chemical formula LiF. It is a colorless solid that transitions to white with decreasing crystal size. Its structure is analogous to that of sodium chloride, but it is much less soluble in water. ...

) 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 (haloalkanes dehalogenases, HLDs).

Literature

* *{{cite web, title=transhalogenation - Wiktionary, periodical=, publisher=, url=https://en.wiktionary.org/wiki/transhalogenation, url-status=, format=, access-date=, archive-url=, archive-date=, last=, date=27 October 2018, language=, pages=, quote=

References

Chemical reactions