Sciencemadness Discussion Board

Nucleophilic substitution on an alky fluoride

Nasalguad - 6-10-2015 at 16:46

Hi everyone, have a question that I just can't seem to wrap my head around. I recently came across an old canister of 1,1,1,2-Tetrafluoroethane, an old refridgerant, and started thinking about what sorts of reactions it would undergo. I started thinking of possible products that would form from passing a stream of Tetrafluoroethane gas through a sodium hydroxide solution. Would the reaction generate four molecules of NaF and a tetrally substituted ethane molecule? or would the reaction cease once one or two hydroxyl groups are added due to steric effects from the hydroxide groups?

blogfast25 - 6-10-2015 at 16:50

https://en.wikipedia.org/wiki/Tetrafluoromethane#Reactions

Trust me, it's the same for 1,1,1,2-Tetrafluoroethane.

MeshPL - 7-10-2015 at 04:58

It will not react with NaOH, but with Na it may actually produce some NaF. The only problem is, the fact that tetrafluoroethane is gaseous in room temperature will reaction with Na would be exothermic and may require preheating. So all your reagent may escape. And in fact the reaction mixture may explode :P.

In fact Teflon, which is a highly substituted fluorocarbon makes a good flash powder with Mg, so tetrafluoromethane may as well :D.

[Edited on 7-10-2015 by MeshPL]

blogfast25 - 7-10-2015 at 06:02

Quote: Originally posted by MeshPL  
It will not react with NaOH, but with Na it may actually produce some NaF. The only problem is, the fact that tetrafluoroethane is gaseous in room temperature will reaction with Na would be exothermic and may require preheating. So all your reagent may escape. And in fact the reaction mixture may explode :P.

In fact Teflon, which is a highly substituted fluorocarbon makes a good flash powder with Mg, so tetrafluoromethane may as well :D.

[Edited on 7-10-2015 by MeshPL]


Halogenated carbons and alkali metals are a recipe for disaster.

gdflp - 7-10-2015 at 06:33

This can actually be used to make a really nice demonstration. If a small(3mm x 3mm x 3mm) piece of sodium is placed in a test tube and melted over a flame, a few drops of an alkyl iodide can be added. This results is a sharp crackle, followed by tube filling with purple iodine vapor, the reaction is actually quite beautiful. This is also one way of fusing the iodide into sodium iodide, so further tests can be performed and the organic compound qualitatively determined.

MeshPL - 7-10-2015 at 07:59
Quote:

Halogenated carbons and alkali metals are a recipe for disaster.


Everything depends on concentration and amount. I thought it was a recipe for Wurtz reaction, which is a really crappy C-C bond formation ;).

But still don't mess with alkali metals + halocarbons.

Nasalguad - 13-10-2015 at 14:07

Thanks everbody who responded that is all exactly what I was looking for and fantastic information. Well now that alcohol formation is out of the question, anybody got any ideas on any non-explosive reactions that I could do with this stuff?