Ochem Question

[jmick101]

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Hello everyone, I have a question that I was sure I was right on but Topscore said I was wrong. On Ochem test #3 it asks an NMR question along the lines of "which one of these will show only one resonance peak in the NMR spectrum?"
and it has
a. Benzene with two Bromines at opposite ends.
b. CH3-C(triple bond)N
c. CH3-0-CH3
d. Two of the above
e. All the above

Di-substituted benzene would show 2 equivalent doublets, and would therefore disqualify it. b would show a 3H singlet and c would show a 6H sinlget. I said the answer was d, but Topscore said it was e. Would someone enlighten me please?

 

[parkwod]

If the bromines are para to one another then all of the hydrogens will be equivalent because the compound is symmetrical. Hope that makes sense 🙂

 

[SF85tea]

i would say the answer is e. parkwod already explained the answer🙂

 

[Chga]

E is correct, b/c all hydrogents are under same condition in the benzene, No matter how you rotate it. 👍

 

[jmick101]

Yeap, you guys were right, p bromo benzene does show up as a huge singlet. I feel lame because I thought I was an NMR guru. My Ochem teacher had NMR's on every single test she gave. Guess I need some review.