Transhalogenation

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.{{cite book|surname1=Yoel Sasson|title=PATai's Chemistry of Functional Groups|periodical=PATai's Chemistry of Functional Groups|chapter=Formation of Carbon-Halogen Bonds (Cl, Br, I)|publisher=John Wiley & Sons, Ltd|location=Chichester, UK|at=pp. pat0011|isbn=978-0-470-68253-1|date=2009-12-15|doi=10.1002/9780470682531.pat0011}} 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.{{Cite patent| country= DE | number = 68918542T | title = Verfahren zur Transhalogenierung einer Halogenphosphor-Verbindung mit Fluorwasserstoff | pubdate = 1989-08-30 }}

File:Transhalogenation2.png

As a halogen source for transhalogenation, metal halides (such as sodium fluoride or lithium fluoride) 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.{{citation|surname1=Gerd Bir, Wolfgang Schacht, Dieter Kaufmann|periodical=Journal of Organometallic Chemistry|title=Eine allgemeine, einfache und schonende Synthesemethode für Fluororganylborane|volume=340|issue=3|at=pp. 267–271|issn=0022-328X|date=1988-02-23|language=German|doi=10.1016/0022-328X(88)80020-2}} It is also possible to produce aryliodides from the corresponding aryl chlorides or aryl bromides.{{citation|surname1=Alex C. Bissember, Martin G. Banwell|periodical=The Journal of Organic Chemistry|title=Microwave-Assisted Trans-Halogenation Reactions of Various Chloro-, Bromo-, Trifluoromethanesulfonyloxy- and Nonafluorobutanesulfonyloxy-Substituted Quinolines, Isoquinolines, and Pyridines Leading to the Corresponding Iodinated Heterocycles†|volume=74|issue=13|at=pp. 4893–4895|issn=0022-3263|date=2009-07-03 |doi=10.1021/jo9008386|pmid=19480440}}

One investigation showed a possibility to perform transhalogenation by means of genetically modified enzymes (haloalkanes dehalogenases, HLDs).{{citation|surname1=Andy Beier, Jiri Damborsky, Zbynek Prokop|periodical=Advanced Synthesis & Catalysis|title=Transhalogenation Catalysed by Haloalkane Dehalogenases Engineered to Stop Natural Pathway at Intermediate|at=pp. adsc.201900132|issn=1615-4150|date=2019-04-17 |volume=361 |issue=11 |doi=10.1002/adsc.201900132|doi-access=free}}

• {{cite book|surname1=Yoel Sasson|title=PATai's Chemistry of Functional Groups|periodical=PATai's Chemistry of Functional Groups|chapter=Formation of Carbon-Halogen Bonds (Cl, Br, I)|publisher=John Wiley & Sons, Ltd|location=Chichester, UK|at=pp. pat0011|isbn=978-0-470-68253-1|date=2009-12-15 |doi=10.1002/9780470682531.pat0011

}}

• {{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=}}

Category:Chemical reactions