Dat Destroyer Orgo Version 2014: #60

[drsuess]

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Answer is B.

A little confused with this question. According to chad's, primary alcohols will react via SN2 with H-X. Secondary and tertiary react via SN1. Since this is a primary alcohol shouldn't H-Cl form the correct product?

The solution says "Choice C is not correct since a shift would occur to give 2-chloro-2-methyl propane".

Thanks for the help!

 

[KineticFlow603]

H from HCl will protonate the OH and it will make H3O+, making it leave. Then you will have a primary carbocation left, which then a hydride shift will occur to form a more stable carbocation, forming a tertiary carbocation. There is a slow-step, meaning it is not a Sn2 reaction.

 

[amneil13]

I could be wrong, but I think that HCl requires a catalyst such as ZnCl2 in order to perform SN2 with primary alcohols. HBr and HI can do it on their own, but HCl shares its electrons more tightly and therefore won't go as readily through SN2 without help. Again, could be wrong but that's what I remember. Perhaps if C was HCl, ZnCl2 it may be correct. Hope that helps and doesn't just put you on the wrong path haha

 

[amneil13]

kineticflow603 is right I believe. Maybe rewatch Chad's and see if you misunderstood?

 

[drsuess]

Interesting, not sure anymore lol.

So would that mean if a primary alcohol has more a substituted neighbor it will proceed via Sn1? I'm still a little confused as to when can you expect a primary alcohol to react via Sn1. Chad made it seem like primary alcohols always react in a Sn2 fashion and his review sheet explicitly states that primary alcohols proceed via Sn2 with H-X. Looking over his lecture he uses HI and HBr for his examples with primary alcohols (so your theory amneil13 could be correct as well).

 

[jwan14]

It could be something that he didn't cover because he thought they wouldn't ever try and trick us like that but all is fair game when it comes to destroyer haha. However, if you look at his list of reactions outline there is one where an alcohol reacts with HCl/ZnCl2 instead of just HCl to form an alkyl chloride. But the specific example deals with a secondary alcohol so who knows!

 

[syeh3]

Whenever u see Cl as product when u see Oh most 100% of the time it's socl2 🙂

 

[shyfox9p]

View attachment 183323

Answer is B.

A little confused with this question. According to chad's, primary alcohols will react via SN2 with H-X. Secondary and tertiary react via SN1. Since this is a primary alcohol shouldn't H-Cl form the correct product?

The solution says "Choice C is not correct since a shift would occur to give 2-chloro-2-methyl propane".

Thanks for the help!

Hey! Learn the roadmaps! It has helped me big time. I didn't even have to look at the choices to give you the answer.