Advanced Organic Chemistry: H-1 NMR spectrum of propanone

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The H-1 hydrogen-1 (proton) NMR spectrum of propanone (acetone)

Doc Brown's Chemistry Advanced Level Pre-University Chemistry Revision Study Notes for UK IB KS5 A/AS GCE advanced A level organic chemistry students US K12 grade 11 grade 12 organic chemistry courses involving molecular spectroscopy analysing H-1 NMR spectra of propanone

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H-1 proton NMR spectroscopy - spectra index

low and high resolution H-1 proton nmr spectrum of propanone analysis interpretation of chemical shifts ppm spin spin line splitting diagram H1 1-H nmr for acetone doc brown's advanced organic chemistry revision notes

TMS is the acronym for tetramethylsilane, formula Si(CH3)4, whose protons are arbitrarily given a chemical shift of 0.0 ppm. This is the 'standard' in 1H NMR spectroscopy and all other proton shifts, called chemical shifts, depend on the individual (electronic) chemical environment of the hydrogen atoms in an organic molecule - propanone here.

The chemical shifts quoted in ppm on the diagram of the H-1 NMR spectrum of propanone represent the peaks of the intensity of the chemical shifts of (which are often groups of split lines at high resolution) AND the relative integrated areas under the peaks gives you the ratio of protons in the different chemical environments of the propanone molecule.

propanone (acetone, dimethyl ketone), C3H6O,  aldehydes and ketones nomenclature (c) doc b, aldehydes and ketones nomenclature (c) doc b, aldehydes and ketones nomenclature (c) doc b , aldehydes and ketones nomenclature (c) doc b

Interpreting the H-1 NMR spectrum of propanone  (acetone)

For relatively simple molecules, the low resolution H-1 NMR spectrum of propanone is a good starting point.

The hydrogen atoms (protons) of propanone occupy only one chemical environments so that the low resolution NMR spectra should show just 1 peak for a H-1 NMR chemical shifts (diagram above for propanone).

CH3COCH3  or  (CH3)2C=O

The high resolution spectrum of propanone

All low and high resolution spectra of propanone just show one groups of protons and no splitting observed.

All 6 protons of propanone are equivalent to each other i.e. they all exist in the same chemical environment.

The C=O group separates the two groups of methyl protons and so inhibits the spin - spin coupling, hence no resonance line splitting, so the H-1 NMR resonance at 2.16 ppm occurs as a singlet.

Number of protons 1H causing splitting Splitting pattern produced from the n+1 rule and the theoretical ratio of line intensities
0 means no splitting             1            
1 creates a doublet           1   1          
2 creates a triplet         1   2   1        
3 creates a quartet       1   3   3   1      
4 creates a quintet     1   4   6   4   1    
5 creates a sextet   1   5   10   10   5   1  
6 creates a septet 1   6   15   20   15   6   1

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Links associated with propanone

The chemistry of ALDEHYDES and KETONES revision notes INDEX

H-1 proton NMR spectroscopy index  (Please read 8 points at the top of the 1H NMR index page)


All Advanced Organic Chemistry Notes

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