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Topic: Help identifying unknown from C13 NMR  (Read 4093 times)

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Offline RayFlacco

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Help identifying unknown from C13 NMR
« on: January 25, 2015, 10:50:07 PM »
So far I know that it is an ester which is liquid at room temperature. The boiling point is around 90 degrees celsius, it's just that I'm not sure how to identify it. From my pretty awful attempt to identify, it ended up being methyl glycinate which it can't be as it is a white powder so I'm a bit stuck. Also the refractive index is n = 1,420. The solvent is chloroform.




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« Last Edit: January 26, 2015, 05:00:23 AM by Dan »

Offline Dan

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Re: Help identifying unknown from C13 NMR
« Reply #1 on: January 26, 2015, 05:10:09 AM »
From my pretty awful attempt to identify, it ended up being methyl glycinate which it can't be as it is a white powder so I'm a bit stuck.

What was your logic? We ask that you show your attempts (including working).

Is the other data given to you or did you determine it experimentally yourself? How do you know it's an ester?

Do you have any other data? Identification from 13C NMR, bp and refractive index does not seem to be a particularly sensible exercise to me...
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Offline RayFlacco

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Re: Help identifying unknown from C13 NMR
« Reply #2 on: January 26, 2015, 06:46:45 AM »
Hi and thanks for your answer.

I did some experiments prior to this and determined that it was an ester with basic hydrolysis. All data is determined experimentally by myself atually.

My logic behind (and excuse my bad english) is that the one at 167,743 is a C-O double bond. At 53,006 i have an O-C and the last one I had to search up the chemical shift to find out what matches at around 40,645 which would be a C bonded with NH2.

I don't have any more information. I asked the professor if this was really enough, and he told me that I had to analyze the NMR and I would be able to find out.


Offline RayFlacco

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Re: Help identifying unknown from C13 NMR
« Reply #3 on: January 26, 2015, 06:59:03 AM »
Ohh I forgot one thing. It's soluble in water, ethanol, sodium hydroxide but not soluble in hydrogen chloride.

Offline RayFlacco

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Re: Help identifying unknown from C13 NMR
« Reply #4 on: January 26, 2015, 07:14:41 AM »
Could it be methyl chloroacetate? I figured that I have listed the bp wrongly as it was actually 128 degrees celcius. Methyl chloroacetate matches with a refractive index at 1,422, the bp is 130 degrees celcius, it's listed as a clear colourless liquid and the predicted NMR matches almost perfectly.

Offline Dan

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Re: Help identifying unknown from C13 NMR
« Reply #5 on: January 26, 2015, 08:01:14 AM »
Could it be methyl chloroacetate? I figured that I have listed the bp wrongly as it was actually 128 degrees celcius. Methyl chloroacetate matches with a refractive index at 1,422, the bp is 130 degrees celcius, it's listed as a clear colourless liquid and the predicted NMR matches almost perfectly.

I was going to suggest that, but the bp looked too far out before this correction.

The solubility data looks a bit odd though. I would expect poor water solubility, and it seems a bit odd that it is soluble in water but not HCl.

I assume by "hydrogen chloride" you mean a hydrochloric acid solution and not HCl gas?
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