Organic Chem Question: Br2 addtion to alkene..pls help

[Henn]

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i know that the first answer is right, but not sure the rest..pls help

 

[Lily-VA]

Second one also produces that product.

 

[blue_moon01]

i know that the first answer is right, but not sure the rest..pls help

Maybe the second and last one
THe other two are too hindered?

edit:

I take it back

 

[Henn]

if the second one and last one are right, why not the third one?

 

[Uracil]

because that is the correct alkene molecule for the Br2 addn... I wish I could explain, Im a bad teacher 😳 Let me think about it, and then I'd come back to it.

EDIT: ok because that first molecule is the only one that can give the product like that...I know it's a weak explanation...but think that the molecules must add C=C, one Br to each Carbon involved in the double bond. Now look at the product. Therefore, the other choices are completely wrong.

 

[Lily-VA]

1)you got it
2) CH2=C(CH3)-CH2-CH3 -> 1,2-dibromo 2-methyl butane
3) CH3C(CH3)=CH-CH3 -> 2,3-dibromo 2-methyl butane
4) CH3-CH=C(CH3)2 -> 2,3-dibromo 2-methyl butane
5) Rearrangement gives 1,2-dibromo 2-methyl butane (Br wants stable environment)

So..1, 2, and 5. Let me hear what other people think~🙂

 

[blue_moon01]

whoa!

 

[Henn]

hmm...now i knew how # 2 is correct..but not the last one though..😕

 

[Lily-VA]

Um..this better not be a DAT Question...this took me a while to figure out..deng...😀

Hey, where is this question from?

 

[Uracil]

1)you got it
2) CH2=C(CH3)-CH2-CH3 -> 1,2-dibromo 2-methyl butane
3) CH3C(CH3)=CH-CH3 -> 2,3-dibromo 2-methyl butane
4) CH3-CH=C(CH3)2 -> 2,3-dibromo 2-methyl butane
5) Rearrangement gives 1,2-dibromo 2-methyl butane (Br wants stable environment)

So..1, 2, and 5. Let me hear what other people think~🙂

👍 oh, I didnt read the question completely. That's right

 

[Henn]

it's from my organic chem homework..
hmm..i think the last one is wrong