Interesting inter-conversions of carbon compounds

[new hand]

Homework Statement

CH₂=CHCHCH₃ + X --> CH₃CHClCH₂CH₃

CH₃CHClCH₂CH₃ + KOH(aq) --> Y
then what is the structural formula of Y ?? (show clearly where the functional group located)

The Attempt at a Solution

It is obvious that X is HCl, and Y should be an alcohol but where is the hydroxyl group be attached and why?

 

[Borek]

https://en.wikipedia.org/wiki/Markovnikov's_rule

 

[new hand]

can you draw the structural formula for me?? I am really confused

 

[new hand]

My answer is 2-methylpropanol but someone told me that it is butan-1-ol which one is correct?

 

[Borek]

2-methylpropanol

Why do you think the straight chain of the original alkene gets rearranged?

 

[new hand]

As OH group will replace the chlorine atom in the second carbon atom (counted from the left)as written in the question
Correct or not?

 

[Borek]

Yes, OH replaces the Cl. But why do you think it ends with the conversion of a straight C-C-C-C chain to a branched one?

 

[new hand]

Yes, OH replaces the Cl. But why do you think it ends with the conversion of a straight C-C-C-C chain to a branched one?

As CH₃CHClCH₂CH₃ is changed to CH₃CH(OH)CH₂CH₃

Oh my mistake!
is the answer butan-2-ol?

 

[Borek]

Looks like.

 

[Merlin3189]

Can a non-chemist just query a couple of points please?

In the OP

CH₂=CHCHCH₃ + X --> CH₃CHClCH₂CH₃

On the LHS it looks to me like the third C should have another H ? And if X is HCl, there seems to be one H short on the LHS? ( C₄H₇ +HCl -> C₄H₉Cl )

In Borek's first response, Markovnikov's rule seems to tell us where the Cl gets substituted, which is not the question? The position of the Cl seems to be shown already in the second equation and the question seems to be, where does the OH get put when it substitutes for the Cl. In my naivety, I simply guessed the OH would go in the same place as the Cl, but does Markovnikov have something to say about it?
When I looked it up (I didn't know it) it seemed to apply to A-C=C-B + HX situations. But in the second reaction, the double bond is already gone and we're looking at P-CCl-Q + OH^-

 

[Borek]

On the LHS it looks to me like the third C should have another H ? And if X is HCl, there seems to be one H short on the LHS? ( C4H7 +HCl -> C4H9Cl )

Yep, the equation was a little bit lousy.

Markovnikov's rule seems to tell us where the Cl gets substituted, which is not the question?

Yes, but that's actually the only thing that matters here, as the next step is just an S_N reaction in which (as you correctly assumed) -OH replaces -Cl. So the final product is defined by the way HCl reacts with the double bond.