Which Product Won't Be Obtained in a Wurtz Reaction?

[baldbrain]

Homework Statement

Which one of the following products will not be obtained in the given Wurtz reaction?

The Attempt at a Solution

Well, (a) will definitely be the major product. We know that this reaction may proceed by a free radical or an ionic mechanism. But what's that got to do with the C-14 shifting position inside the ring? Any help?

 

[TeethWhitener]

It might help to draw out the resonance structures of the radical/ionic intermediate.

 

[baldbrain]

It might help to draw out the resonance structures of the radical/ionic intermediate.

Well, won't that conversion require additional energy? Do we presume it is available?

 

[TeethWhitener]

Well, won't that conversion require additional energy?

Why? Maybe draw the hydrogens explicitly.

 

[baldbrain]

Why? Maybe draw the hydrogens explicitly.

What difference does that make? Won't THIS $\downarrow$ require additional energy?

 

[TeethWhitener]

Won't THIS ↓↓\downarrow require additional energy?

Google "allyl radical."

 

[baldbrain]

Google "allyl radical."

****, you're right...I keep forgetting that.

 

[TeethWhitener]

https://www.masterorganicchemistry....e-allyl-cation-allyl-radical-and-allyl-anion/
Here's a page giving a very good overview of the resonance stability of allyl ions/radicals from the point of view of frontier molecular orbital theory.

 

[baldbrain]

I don't know why, but I still don't have a keen eye spotting the allyl radical. Get me?

 

[baldbrain]

You might remember I stumbled upon this 'allyl' thingy even in that "same S_N1 & S_N2 product" problem.
Anyway, Thanks again.

 

[TeethWhitener]

I don't know why, but I still don't have a keen eye spotting the allyl radical.

It's not a bad idea to have the possibility of allylic resonance in the back of your mind whenever you see a double bond. Other than that, I'm not sure there are any tricks to remembering it.

 

[baldbrain]

I forgot to mention that the answer would be (d). You might've already guessed that.