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Topic: Dehalogenating fluoroalkanes  (Read 2395 times)

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Offline AndersHoveland

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Dehalogenating fluoroalkanes
« on: May 16, 2012, 02:07:21 AM »
Fluorine is typically nearly impossible to remove from organic molecules. But there are at least three ways of doing it.


Quote
researchers [Alan Goldman] at Rutgers University in New Jersey have cracked the problem by using a catalyst based on an iridium centre clamped between two bulky dialkylphosphino groups - a so-called pincer-ligated complex.
http://www.rsc.org/chemistryworld/News/2011/June/23061103.asp
 
Sodium hydride, in the presence of catalytic quantities of nickel acetate and sodium isopropylate, can reduce aryl fluorides (such as p-fluorotoluene) under mild conditions. 90% conversion in 3 hours, 100% within 7 hours. It is important that the nano-sized particulate NaH be used, for maximum surface area.
"An effective method for the hydrodehalogenation of organic halides", Haiqing Li, Shijian Liao, Yun Xu, Daorong Yu and Zhiming Qiao
http://www.springerlink.com/content/84ql762532j36m60/

strong fluorine abductors (such as BF3 or SbF5) can work through the transient formation of the carbenium ion ion, but this can be very hazardous and impractical. (remember that the resulting alkylating agents from the reaction can be deadly, it would be much like working with magic methyl)
CH3F + SbF5 --> CH3+ + SbF6[-]
CH3+ + acetate[-] --> methyl acetate ester

Offline Hunter2

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Re: Dehalogenating fluoroalkanes
« Reply #1 on: May 16, 2012, 04:34:59 AM »
Using Tetraetch : Sodium dissolved in aa Tetrahydrofurane solution containing naphthalene.

Sodium dissolved in liquid ammonia


Offline OC pro

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Re: Dehalogenating fluoroalkanes
« Reply #2 on: May 18, 2012, 02:21:27 PM »
@Anders Hoveland: The first paper is a joke.  ;D Reminds me of oxidations of alcohols mediated through NaH. Chinese researchers had submitted to JACS and it got somehow accepted. After six month the paper was retracted.

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