Sciencemadness Discussion Board

Alpha halogenation

Sherlock Holmium - 15-6-2018 at 23:08

Just a quick question: Does alpha halogenation of a ketone occur on the least or most substituted carbon?

HeYBrO - 16-6-2018 at 01:21

just a quick note: spoon feeding is not permited here

solo - 16-6-2018 at 12:05

.....maybe you can read about it.....solo

https://chemistry.stackexchange.com/questions/23500/regiosel...

Assured Fish - 16-6-2018 at 13:51

Lets turn this thread into something more useful.
I have a question pretaining to enols.

I ask because i have never found an example of this being done before despite my research.
Would it be possible to reflux a ketone in an excess of say HBr to form a halo alkene.
The following is the reaction i wish to accomplish.


HBr halogenation of hydroxy acetone.png - 3kB

I suppose this would really be a question of, would the HBr attack the alkene or would it rather attack the hydronium leaving group.

Then i guess the other issue is under the harsh condition of refluxing there may be other side reactions involving HBr adding across the double bond of 1,2 dibromopropene.

Perhaps a similar reaction could be accomplished using a much stronger halogenating agent such as thionyl halide or phosphorous trihalide which would perhaps mitigate the harsh conditions required for a hydrogen halide to accomplish the same task.
Any input would be appreciated?

HeYBrO - 16-6-2018 at 22:40

I think you should draw out the full mechanism of what you are proposing

Assured Fish - 16-6-2018 at 22:48

New thread to go with it too i reckon.



[Edited on 17-6-2018 by Assured Fish]