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Topic: NMR help  (Read 3206 times)

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Offline meepin

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NMR help
« on: July 11, 2013, 10:33:50 PM »
Hi all, I'm struggling a bit with this NMR assignment.

Here is the structure:


Here is the H NMR


I'm guessing the COOH (a) isn't shown because of deuterium exchange.

I'm guessing b would be at 7.7 b/c it's so close to an EN group. Then c would be at 7.5.

6.9 would represent e and g. They would be shifted downfield because of the methoxy group.

6.3 would represent d and f...because those are the only ones left.

h is at 3.832 b/c it's the only one representing 3 Hs due to integration.

Because e and g are equivalent, they would appear at the same spot and still be simply counted as a doublet right? same for d and f? Thanks in advance for anyone's input!

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« Last Edit: July 12, 2013, 06:50:31 AM by Dan »

Offline Dan

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Re: NMR help
« Reply #1 on: July 12, 2013, 06:52:30 AM »
Hint: Pay attention to the coupling constants.
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Offline meepin

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Re: NMR help
« Reply #2 on: July 13, 2013, 11:55:05 PM »
Hint: Pay attention to the coupling constants.

I'm afraid I don't understand - how would coupling constants help?

Offline Dan

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Re: NMR help
« Reply #3 on: July 14, 2013, 06:17:59 AM »
If A couples to B with J = X Hz, then B couples to A with J = X Hz.

i.e. the signals for Hs that couple to each other should have matching coupling constants.
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