Rachana Gheewala
Chem 242 extra credit assignment
NMR spectrum of Pentan-2-one


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PENTAN-2-ONE

Empirical Formula: C5H10O
Molecular Weight: 86.1323
Nominal Mass: 86 Da
Average Mass: 86.1323 Da

source: http://www.chemspider.com/Chemical-Structure.7607.html





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Below is the complete 1H NMR Spectrum of Pentan-2-One :
whole_spectrum
Being that there are four peaks, I will do a detailed analysis of each peak that pertains to this molecule.


1
By starting at the extreme left of the spectrum, I will begin by analyzing the graph above which depicts a triplet of 2H approximately δ 2.38. These peaks represent a Carbon #3, (also known as a –CH2) It is clear that this is a triplet because it is right next to another –Ch2. Being that this peak is right next to a carbonyl group, it will typically range from approximately 2.4-2.1 ppm which is exactly what this peak demonstrates.

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This peak represents a singlet of CH3 in the compound which is right next to the carbonyl group (CO) . As mentioned above, a peak that is right next to the carbonyl group will typically range from 2.4-2.1 ppm which is what this peak demonstrates.
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This peak represents a quintuplet which has 5 peaks. This peak is the second ch2 which is in between the ch3 and ch2 in the compound. A triplet of quartets is also common within this group of carbons however due to overlapping, it is unclear whether a quintuplet has formed, or whether there are actually three groups of quartets which are hidden under each other. Lastly, this is an sp3 carbon, and therefore it is expected to have a range of approximately 1.6 ppm which is what these peaks demonstrate.

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Lastly, this peak, which is extremely similar to the first peak that was analyzed, is a triplet which represents the CH2 which is next to the Ch3. Again, being that there is a CH2 that is next to this structure, a triplet has formed.