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Transhalogenation

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Transhalogenation is a substitution reaction in which the halide 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

An enzyme-catalyzed transhalogenation.

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. 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

References

  1. Hudlicky, Milos; Hudlicky, Tomas (1983). "Formation of carbon-halogen bonds". Halides, Pseudo-Halides and Azides: Part 2 (1983). pp. 1021–1172. doi:10.1002/9780470771723.ch3. ISBN 9780470771723.
  2. ^ Yoel Sasson (2009-12-15). "Formation of Carbon-Halogen Bonds (Cl, Br, I)". PATai's Chemistry of Functional Groups. Chichester, UK: John Wiley & Sons, Ltd. pp. pat0011. doi:10.1002/9780470682531.pat0011. ISBN 978-0-470-68253-1. {{cite book}}: |periodical= ignored (help)
  3. DE 68918542T, "Verfahren zur Transhalogenierung einer Halogenphosphor-Verbindung mit Fluorwasserstoff", published 1989-08-30 
  4. Gerd Bir, Wolfgang Schacht, Dieter Kaufmann (1988-02-23), "Eine allgemeine, einfache und schonende Synthesemethode für Fluororganylborane", Journal of Organometallic Chemistry (in German), vol. 340, no. 3, pp. 267–271, doi:10.1016/0022-328X(88)80020-2, ISSN 0022-328X{{citation}}: CS1 maint: multiple names: authors list (link)
  5. Alex C. Bissember, Martin G. Banwell (2009-07-03), "Microwave-Assisted Trans-Halogenation Reactions of Various Chloro-, Bromo-, Trifluoromethanesulfonyloxy- and Nonafluorobutanesulfonyloxy-Substituted Quinolines, Isoquinolines, and Pyridines Leading to the Corresponding Iodinated Heterocycles†", The Journal of Organic Chemistry, vol. 74, no. 13, pp. 4893–4895, doi:10.1021/jo9008386, ISSN 0022-3263, PMID 19480440
  6. Andy Beier, Jiri Damborsky, Zbynek Prokop (2019-04-17), "Transhalogenation Catalysed by Haloalkane Dehalogenases Engineered to Stop Natural Pathway at Intermediate", Advanced Synthesis & Catalysis, vol. 361, no. 11, pp. adsc.201900132, doi:10.1002/adsc.201900132, ISSN 1615-4150{{citation}}: CS1 maint: multiple names: authors list (link)
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