Where are carbo-cations formed in this nucleophilic substitution reaction?

[Oblivion77]

Homework Statement

The Attempt at a Solution

I'm confused on what is happening in this reaction, and where carbo-cations are being formed. Any help would be great. Thanks.

 

[PhaseShifter]

What would you expect to happen in the first step, when HBr is added?

 

[Oblivion77]

What would you expect to happen in the first step, when HBr is added?

Well The H would attack the double bonds and form the most stable carbo-cation?

 

[PhaseShifter]

Correct. So what remains is determining whether the ends of each double bond are primary, secondary, or tertiary carbons to determine the relative stabilities of carbocations.

Once you know where the hydrogen and bromine go, you move on to the second step, which is a nucleophilic substitution using methoxide ions.

 

[Oblivion77]

Correct. So what remains is determining whether the ends of each double bond are primary, secondary, or tertiary carbons to determine the relative stabilities of carbocations.

Once you know where the hydrogen and bromine go, you move on to the second step, which is a nucleophilic substitution using methoxide ions.

Thanks for the help, I understand the first step and where the bromine's attach to. What exactly is happening in the second step with the methoxide ions?

 

[PhaseShifter]

Nucleophilic substitution.