Yatayyat
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Link to Q: https://imgur.com/9ToCiL0

What necessary steps do you take to find the identity of this alkene?

I'm aware of the mechanisms that take hold here and how they will be drawn out.

1st one is electrophilic addition in which the C=C double bond gets broken as well as the Br- electrophile attaching itself to the carbocation intermediate.

Then this 2-bromobutane undergoes nucleophilic substitution with a cyanide ion nucleophile, resulting in a nitrile (supposedly named 2-methylpropanenitrile)

But I can't see how would I quickly find which is the correct alkene to start off with to produce our final amine?

Any help is appreciated. Thanks!
Last edited by Yatayyat; 1 year ago
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Pigster
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(Original post by Yatayyat)
Link to Q: https://imgur.com/9ToCiL0

What necessary steps do you take to find the identity of this alkene?

I'm aware of the mechanisms that take hold here and how they will be drawn out.

1st one is electrophilic addition in which the C=C double bond gets broken as well as the Br- electrophile attaching itself to the carbocation intermediate.

Then this 2-bromobutane undergoes nucleophilic substitution with a cyanide ion nucleophile, resulting in a nitrile (supposedly named 2-methylpropanenitrile)

But I can't see how would I quickly find which is the correct alkene to start off with to produce our final amine?

Any help is appreciated. Thanks!
The LiAlH4 is reducing the nitrile.

Work back from there.
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Yatayyat
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(Original post by Pigster)
The LiAlH4 is reducing the nitrile.

Work back from there.
Thanks for replying

I've tried working back like you have said but I'm still struggling in what the last step would look like from going from a halogenoalkane back into a alkene in this https://imgur.com/n4Xoffa

I'm not even sure if I've drawn the compound in displayed formula correctly from the skeletal formula they have given me?
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Yatayyat
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From a chemrevise sheet that I've seen before, when a nitrile is reduced into an amine using LiAlH4 reagent.

The nitrile compound loses a "CH2" in its carbon chain and the "CN" gets replaced with "NH2"

Name:  Screenshot 2019-06-17 at 17.10.23.png
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invisiblebird
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I think what you've done is correct so far. Afterwards there are two ways in which you could go back to the alkene from the halogenoalkane, but the only one that is an option in the question is but-2-ene.Name:  IMG_2320.jpg
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Yatayyat
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(Original post by invisiblebird)
I think what you've done is correct so far. Afterwards there are two ways in which you could go back to the alkene from the halogenoalkane, but the only one that is an option in the question is but-2-ene.Name:  IMG_2320.jpg
Views: 32
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Hmm I understand what you mean, but why I'm I getting this as my halogenoalkane?

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Edit: Nevermind the position of "CH3" and "Br" can be swapped to get the halogenoalkane that you got right?
Last edited by Yatayyat; 1 year ago
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invisiblebird
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(Original post by Yatayyat)
Hmm I understand what you mean, but why I'm I getting this as my halogenoalkane?

Name:  IMG_2577.JPG
Views: 49
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Edit: Nevermind the position of "CH3" and "Br" can be swapped to get the halogenoalkane that you got right?
Yep, it's the same halogenoalkane (2-bromobutane).
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