Orgo Destroyer question #122

[hope_to_match]

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From 2013 destroyer it is asking to predict the major product at -40C with HCl and it is giving a conjugated diene. The explanation talks about 1-2 and 1-4 addition products. Can someone explain this concept to me? Chad did not talk about it and the explanation is not thorough. Thanks. I can post a pic i necessary

 

[Jordwin]

For anyone who wants to help it's similar to problem #110 in the 2012 version (just looked over this problem
Lol).

I'm just memorizing that a higher temperature will allow the 1,4
Addition product to be possible. I think similar reactions occur with HBr (not 100%).

Ik, not that helpful, sorry.

 

[hope_to_match]

For anyone who wants to help it's similar to problem #110 in the 2012 version (just looked over this problem
Lol).

I'm just memorizing that a higher temperature will allow the 1,4
Addition product to be possible. I think similar reactions occur with HBr (not 100%).

Ik, not that helpful, sorry.

haha..well i memorized this as well i guess i just want to know looking at the products which ones are 1,4 and which ones are 1,2 i dont really understand the notation

 

[Jordwin]

haha..well i memorized this as well i guess i just want to know looking at the products which ones are 1,4 and which ones are 1,2 i dont really understand the notation

Ohh gotcha! In both cases the "1" refers to where the hydrogen adds and the second refers to where the Cl adds. Does this help or is that not your question either..? Ha sorry lol

 

[hope_to_match]

Ohh gotcha! In both cases the "1" refers to where the hydrogen adds and the second refers to where the Cl adds. Does this help or is that not your question either..? Ha sorry lol

yes it was! I get it now thanks a lot 🙂

p.s i should probably go to sleep soon ive been studying for like 11 hours already😴

 

[Jordwin]

yes it was! I get it now thanks a lot 🙂

p.s i should probably go to sleep soon ive been studying for like 11 hours already😴

Woo! Yeah it's getting late also lol that's probably a good call. We need to be ready for studying tomorrow!

 

[hope_to_match]

Woo! Yeah it's getting late also lol that's probably a good call. We need to be ready for studying tomorrow!

haha yeah. are you on the eastern time? its 11:10 pm here 😴

 

[Jordwin]

haha yeah. are you on the eastern time? its 11:10 pm here 😴

Nah, central. I guess I have another hour of studying to keep up to yours! Ha

 

[getsome111]

I might remember which question you're asking about, anyone can correct me if im wrong, but I think the concept thats being touched on here is rate vs stability. A tertiary carbocation is initially more stable than a secondary, but a more substituted/resonance stabilized double bone will be in the end more stable. If the reaction is thought of thermodynamically, there is basically a higher energy of activation to form the more stable product, thus without the high activation energy required the carbocation will sit predominantly on the carbon where it is most stable thus c2. I typed out another way of presenting it but I was basically explaining activation energy. hope this helps