Fluorination of acetone?

[Genecks]

I was reading about various halogenations with acetone (Br, I, and Cl). However, does fluorine have the same reaction rate with acetone during halogenation?

 

Yes? No? If not, why so?

[mississippichem]

I was reading about various halogenations with acetone (Br, I, and Cl). However, does fluorine have the same reaction rate with acetone during halogenation?

 

Yes? No? If not, why so?

 

I'm not sure in this particular case, but fluorine is often the "odd man out" of the halogens. Fluorine's huge electronegativity and strong electron affinity make it very hard to polarize which actually makes it quite a poor nucleophile.

 

This is a bit counter intuitive as fluorine is often thought of as a very reactive reagent. It is, but it seems to prefer reacting through homolytic [radical] mechanisms. adding a fluorine atom to organics usually requires a specialized fluorinating agent. The trick with organofluorine chemistry is to find a reagent that will react but is still somewhat selective. Some reagents that will add fluorine go way overboard and fluorinate everything. The quest for mild yet selective fluorinating agents is an ongoing investigation though there are some good ones out there already.

[Horza2002]

As Mississippichem as said, conventional halogenation reactions don't work for flourine...you typically have to use special flourinating agents.

 

I have some experience with diethylaminosulphur triflouride (DAST). If you react DAST with an alcohol, you get the corrosponding alkyl flouride while reacting it with aldehydes or sterically unhindered ketones gives a geminal difluoride (two fluorines bound to the same carbon). There are also a wide range flourinating reagents...this link summarises the most common.

 

http://www.scripps.edu/chem/baran/images/grpmtgpdf/Su_May_08.pdf

http://www.alfa.com/en/docs/FluorinatingAgents.pdf

 

One if find really interesting is using xenon difloruide (XeF₂)...it converts a carboxylic acid into a alkly flouride with a carbon less (carbon dioxide is release). It reacts via a xenonalte ester and release flouride ions. I've done this reaction and it actually works rather good...xeon diflouride is also a nice white solid.

[Genecks]

Xenon is definitely cool. If I had more time, I'd look into how it works. It surely has quite the fascinating chemistry.

 

Thank you for the replies.

 

- genecks

[John Cuthber]

As Mississippichem as said, conventional halogenation reactions don't work for flourine...you typically have to use special flourinating agents.

 

I have some experience with diethylaminosulphur triflouride (DAST). If you react DAST with an alcohol, you get the corrosponding alkyl flouride while reacting it with aldehydes or sterically unhindered ketones gives a geminal difluoride (two fluorines bound to the same carbon). There are also a wide range flourinating reagents...this link summarises the most common.

 

http://www.scripps.edu/chem/baran/images/grpmtgpdf/Su_May_08.pdf

http://www.alfa.com/en/docs/FluorinatingAgents.pdf

 

One if find really interesting is using xenon difloruide (XeF₂)...it converts a carboxylic acid into a alkly flouride with a carbon less (carbon dioxide is release). It reacts via a xenonalte ester and release flouride ions. I've done this reaction and it actually works rather good...xeon diflouride is also a nice white solid.

 

 

Flour is not the same as fluorine.