Easy Orgo Q

[211183]

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2 bromo butane + H+/h2o ... what's the product and mechanism?

 

[Sea of ASH]

i thinkits 2-hydroxybutane SN1

 

[ZenoVT]

I'm going to guess butan-2-ol via Sn1?

 

[doc3232]

What is the point of the acid?
I agree that it will be a very slow SN1 reaction.
very very slow.

 

[211183]

it was on my kaplan exam...
2 butanol is the answer via sn1


does anyone know how this actually proceeds... why does the Br- come off? seems unlikely under those conditions... to me, at least.

 

[doc3232]

So the nucleophile is very weak. Also, you know it can't be elimination because there is no base.
So Br comes off first, then OH2 comes in and attacks the carbocation.
Then the H is picked off the OH2+ group by another water molecule.
The solution will become even more acidic.

 

[211183]

what makes the Br- come off??? doesn't it need heat.. or something to make it?

 

[doc3232]

Br- is a very stable ion. HBr is a strong acid just to give you an idea of its stability.
It isn't a fast reaction as I said, especially because it is a secondary carbon. It leave every once in a while.

 

[Sea of ASH]

also becuz Br is a very good leaving group cuz its a weak base and wants to be picked up by an H

 

[doc3232]

also becuz Br is a very good leaving group cuz its a weak base and wants to be picked up by an H

Br is a very weak base.
You are saying it wants to be picked up by an H?
HBr full dissociates. HBr won't exist in the solutions, only H3O+s and Br-s.

 

[Sea of ASH]

ya i know, i like to think of it like that, i didnt mean that a bond will be made, it wants to chill with the H's in the solution lol

 

[ZenoVT]

-Br comes off by chance to create a carbocation in the polar protic solution

 

[doc3232]

ya i know, i like to think of it like that, i didnt mean that a bond will be made, it wants to chill with the H's in the solution lol

I see, that is a good way to think about it.