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Topic: NMR, IR, and Mass Spec question help identify molecule  (Read 4530 times)

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Offline catman8419

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NMR, IR, and Mass Spec question help identify molecule
« on: April 16, 2015, 11:55:33 AM »
I've tried absolutely everything and can't seem to get it. I've been looking at this for hours.
Can anyone help me?


https://flic.kr/p/s9YpnA
https://flic.kr/p/sa4EGc
« Last Edit: April 16, 2015, 12:45:41 PM by Arkcon »

Offline Borek

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Re: NMR, IR, and Mass Spec question help identify molecule
« Reply #1 on: April 16, 2015, 06:03:35 PM »
I guess have some ideas and you think they are wrong. Can you list them?
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Offline pgk

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Re: NMR, IR, and Mass Spec question help identify molecule
« Reply #2 on: April 16, 2015, 06:53:59 PM »
Diethyl oxalate (CH3CH2OCO-COOCH2CH3)
Simple NMR spectrum means symetric molecule.
Anydrides, alkoyl peroxides and sometimes diesters have two carbonyl bands in IR spectrum.
« Last Edit: April 16, 2015, 07:58:02 PM by pgk »

Offline pgk

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Re: NMR, IR, and Mass Spec question help identify molecule
« Reply #3 on: April 16, 2015, 07:08:30 PM »
Propionic anhydride (CH3CH2CO-O-COCH2CH3), m/z = 130
Dipropionyl peroxide (CH3CH2COO-OCOCH2CH3), m/z = 146, methylene shift near 2.3 ppm.
Diethyl oxalate (CH3CH2OCO-COOCH2CH3), m/z = 146, methylene shift near 4.2 ppm.
« Last Edit: April 16, 2015, 07:57:26 PM by pgk »

Offline Irlanur

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Re: NMR, IR, and Mass Spec question help identify molecule
« Reply #4 on: April 17, 2015, 03:29:20 AM »
Quote
Diethyl oxalate (CH3CH2OCO-COOCH2CH3)
I don't think the solution itself is of any interest, it's about the way right?

It's true, if you have a simple NMR Spectrum and a (compared to that) high Mass, the Molecule must be symmetric.

-What does the H-NMR tell you, catman8419 ?

Offline Vidya

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Re: NMR, IR, and Mass Spec question help identify molecule
« Reply #5 on: April 17, 2015, 11:34:05 AM »
Finger print area indicates a C-O stretch ....C=O and C-O stretch shows a diester ...symmetrical NMR and splitting is also in favor of CH3CH2O group twice in the compound.13C is also showing only three types of carbon ...all these points in the direction of
Diethyl oxalate (CH3CH2OCO-COOCH2CH3), m/z = 146

Offline pgk

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Re: NMR, IR, and Mass Spec question help identify molecule
« Reply #6 on: April 19, 2015, 02:07:01 PM »
Important: Please and in any case, do not confuse optical symmetry {enantiomerism, diastereoisomerism, asymmetric synthesis, etc.} with molecular symmetry {existence of structural symmetry axis) in spectroscopy and chemical physics.

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