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Topic: Finding the mystery ester strucuture using NMR  (Read 5391 times)

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Offline MahderA

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Finding the mystery ester strucuture using NMR
« on: February 20, 2017, 03:51:32 PM »
Dear all,

I have an unknown ester with the chemical formula C9H10O2 that is used as a flavoring agent in candies. It exhibits the following H-NMR and C-NMR (Attached file: unknown ester NMR)

Based on the NMR peaks I believe the unknown is benzyl acetate , as the C-NMR and the first two peaks of H-NMR are identical to the unknown NMR (Attached file: benzyl acetate NMR).

Knowing that aromatic protons are not equivalent, as shown in the unknown's H-NMR at 7.4 and 7.5 ppm, I do not know why the aromatic protons for benzyl acetate are integrated and shown as a singlet.
Is this just due to the sensitivity of the prediction algorithm (I am using Chembiodraw)? Or benzyl acetate is not the unknown?

Your help is greatly appreciated!


Offline AWK

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Re: Finding the mystery ester strucuture using NMR
« Reply #1 on: February 20, 2017, 06:16:18 PM »
It seems to me that your H-NMR shows very good resolution with comparison to literature spectrum ~100 MHz.
AWK

Offline wildfyr

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Re: Finding the mystery ester strucuture using NMR
« Reply #2 on: February 20, 2017, 10:10:31 PM »
His lit NMRs are predictions from chemdraw. Look up the real lit NMRs on SDBS.

Offline Dan

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Re: Finding the mystery ester strucuture using NMR
« Reply #3 on: February 21, 2017, 01:54:04 AM »

Is this just due to the sensitivity of the prediction algorithm (I am using Chembiodraw)? Or benzyl acetate is not the unknown?


ChemDraw predictions are not perfect, they don't match the real spectra 100%, that is normal.
My research: Google Scholar and Researchgate

Offline Irlanur

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Re: Finding the mystery ester strucuture using NMR
« Reply #4 on: February 21, 2017, 07:21:16 AM »
Just pointing out that we are comparing two non-experimental spectra here...

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