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Topic: Phenol proton nmr spectrum  (Read 10308 times)

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Offline mystreet123

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Phenol proton nmr spectrum
« on: April 26, 2016, 06:04:49 AM »
Why does phenol have 4 different proton environment?

I can only think of 3 :(

shouldn't these three protons be in the same environment? as each of them has two neighbouring proton
« Last Edit: April 26, 2016, 06:36:31 AM by mystreet123 »

Offline Arkcon

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Re: Phenol proton nmr spectrum
« Reply #1 on: April 26, 2016, 08:21:15 AM »
Is that structure static?
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline sjb

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Re: Phenol proton nmr spectrum
« Reply #2 on: April 26, 2016, 08:48:01 AM »
But are each of the neighbours also equivalent?

Offline mystreet123

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Re: Phenol proton nmr spectrum
« Reply #3 on: April 26, 2016, 09:58:25 AM »
I don't know

I think they are?

Offline Babcock_Hall

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Re: Phenol proton nmr spectrum
« Reply #4 on: April 26, 2016, 10:06:25 AM »
Does it matter whether a group is ortho to or para to the -OH?

Offline mystreet123

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Re: Phenol proton nmr spectrum
« Reply #5 on: April 26, 2016, 10:52:41 AM »
Does it matter whether a group is ortho to or para to the -OH?

Does it??

Online Borek

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Re: Phenol proton nmr spectrum
« Reply #6 on: April 26, 2016, 11:05:26 AM »
Proton environments are identical only when the distance from all other groups is identical. Are all three protons at the bottom of the molecule as drawn in the same distance from -OH?
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Offline Babcock_Hall

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Re: Phenol proton nmr spectrum
« Reply #7 on: April 26, 2016, 11:23:37 AM »
Does it matter whether a group is ortho to or para to the -OH?

Does it??
If you look at a table of substituent shifts for benzene, you should find that the position of the proton relative to the substituent does matter.  The ortho and para hydrogen atoms in phenol are more upfield than the meta H is.  One can use resonance to explain this result, but perhaps a more sophisticated theory would be better.

Offline mystreet123

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Re: Phenol proton nmr spectrum
« Reply #8 on: April 26, 2016, 11:50:51 AM »
Understood now

Thanks a lot! ;D

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