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Interpreting
and explaining the
H-1
proton NMR spectrum of methyl propanoate
(methyl propionate)
[Author
©
Dr Phil Brown PhD:
Doc Brown's advanced level organic chemistry exam revision notes
suitable for students of UK A level chemistry courses & US K12 grade
11, grade 12 and AP honors chemistry courses: Molecular
spectroscopy - analysing the 1H NMR spectra of
methyl propanoate
[spectra
page updated
April 4th 2026 *]
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1H NMR spectrum of
CH3CH2COOCH3
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H-1 proton NMR spectroscopy -
spectra index
Introductory note on the 1H NMR spectra of methyl propanoate
Students and teachers please note my explanation of the
proton NMR spectrum of methyl propanoate is designed for advanced, but
pre-university, chemistry courses.
The chemical shift
δ splitting pattern effects for
methyl propanoate are
confined to a proton spin-spin
coupling effects analysed using the n+1 rule for adjacent
non-equivalent proton fields (n is the number of neighbouring
protons in a non-equivalent different chemical environment for the
methyl propanoate molecule).
It is assumed that the integrated intensities of the
δ
chemical shifts give the ratio of the protons in the different
non-equivalent chemical environments of the methyl propanoate molecule.
The most common solvent used for investigating the 1H NMR
spectrum of compounds like methyl propanoate, is CDCl3 and other
deuterated solvents to avoid confusion with a 1H NMR
signal, 2D (2H) has a different chemical
shift.
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 resonances, called chemical shifts, are measured
with respect to the TMS, and depend on the
individual (electronic) chemical environment of the hydrogen atoms
in an organic molecule - methyl propanoate here.
The chemical shifts quoted in ppm on the diagram of
the H-1 NMR spectrum of methyl propanoate 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 methyl propanoate molecule.
Methyl propanoate
(methyl propionate)
an ester,
The molecular structure and naming of carboxylic
acids and derivatives
Interpreting the
H-1 NMR spectrum of
methyl propanoate
In terms of spin-spin coupling from the possible proton magnetic orientations,
for methyl propanoate I
have only considered the interactions of
non-equivalent protons on adjacent carbon atoms
e.g. -CH2-CH3, -CH-CH2-, protons
etc.
For relatively simple molecules, the low
resolution H-1 NMR spectrum of methyl propanoate is a good starting point
(low resolution diagram above).
The hydrogen atoms (protons) of methyl
propanoate occupy 3
different chemical environments so that the low resolution NMR
spectra should show 3 principal
1H peaks of different H-1 NMR chemical shifts (diagram above for
methyl propanoate).
CH3CH2COOCH3
Note the proton ratio 3:2:3 of the 3 colours of the protons
in the 3 chemically different proton environments
Chemical shifts
(a) to (c) on the H-1 NMR
spectrum diagram for methyl propanoate.
Although there are 8 hydrogen atoms in the molecule,
there are only 3 possible different chemical
environments for the 8 hydrogen atoms in methyl propanoate molecule.
The integrated signal proton ratio CH3CH2COOCH3 observed
in the high resolution H-1 NMR spectrum, corresponds with
the structural formula of methyl propanoate.
The high resolution 1H NMR
spectrum of methyl propanoate
All low and high resolution spectra of methyl
propanoate
show 3 groups of proton resonances and in the 3:2:3 ratio expected from the
structural
formula of methyl propanoate.
The ppm quoted on the diagram represent the peak
of resonance intensity for a particular proton group in the
molecule of methyl propanoate - since the peak' is at the apex of a band of
H-1 NMR resonances due to spin - spin coupling field splitting effects - see high resolution
notes on methyl propanoate below.
So, using the chemical shifts and applying the
n+1 rule to
methyl propanoate
and make some predictions using some colour coding! (In problem
solving you work the other way round!)
(a) 1H
Chemical shift 1.15 ppm, methyl protons : CH3CH2COOCH3
This resonance is split into a 1:2:1
triplet by the CH2 protons (n+1 = 3).
Evidence for the presence of a CH2 group
in the molecule of methyl propanoate
(b) 1H
Chemical shift 2.32 ppm, CH2 protons : CH3CH2COOCH3
This resonance is split into a 1:3:3:1
quartet by the CH3 protons (n+1 = 4).
Evidence for the presence of a CH3 group
in the molecule of methyl propanoate
(c) 1H
Chemical shift 3.67 ppm, methyl protons: CH3CH2COOCH3
This resonance is recorded as a singlet,
because there are no protons on an adjacent atom.
Evidence from the proton ratio suggests the presence of a
2nd methyl group
in the molecule of methyl propanoate
Note the decreasing effect on the 1H chemical shift as the
proton is further from the more electronegative oxygen atoms in methyl
propanoate.
The splitting pattern from proton
spin-spin coupling effects is analysed using the n+1 rule for
adjacent non-equivalent proton fields (n is the number of
neighbouring protons in a non-equivalent different chemical
environment) and applied to the 1H NMR spectrum of methyl
propanoate.
|
Number of directly adjacent protons 1H
causing splitting |
Splitting pattern produced from the
n+1 rule on spin-spin coupling 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 |
Key words & phrases:
C4H8O2 CH3CH2COOCH3
Interpreting the proton H-1 NMR spectra of methyl propanoate, low resolution & high resolution proton
nmr spectra of methyl propanoate, H-1 nmr spectrum of methyl propanoate, understanding the
hydrogen-1 nmr spectrum of methyl propanoate, explaining the line splitting patterns from
spin-spin coupling in the
high resolution H-1 nmr spectra of methyl propanoate, revising the H-1 nmr spectrum of
methyl propanoate,
proton nmr of methyl propanoate, ppm chemical shifts of the H-1 nmr spectrum of
methyl propanoate,
explaining and analyzing spin spin line splitting in the H-1 nmr spectrum, how
to construct the diagram of the H-1 nmr spectrum of methyl propanoate, how to work out the
number of chemically different protons in the structure of the methyl propanoate organic
molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR
spectrum of methyl propanoate using the n+1 rule to explain the spin - spin coupling ine
splitting in the proton nmr spectrum of methyl propanoate deducing the nature of the protons
from the chemical shifts ppm in the H-1 nmr spectrum of methyl propanoate
examining the 1H nmr spectrum of methyl propanoate analysing the 1-H nmr spectrum of
methyl propanoate
how do you sketch and interpret the H-1 NMR spectrum of methyl propanoate
interpreting interpretation of the 1H proton spin-spin coupling causing line
splitting in the NMR spectrum of methyl propanoate
assignment of chemical shifts in the
proton 1H NMR spectrum of methyl propanoate formula explaining spin-spin coupling for line splitting
for methyl propanoate
methyl
propionate ester
functional group
How do you interpret the H-1 NMR spectrum of
methyl propanoate How to interpret
the H-1 NMR spectrum of methyl propanoate Explanatory diagram of the chemical
shifts of the 1H H-1 proton NMR spectrum of the methyl propanoate
molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the
proton NMR spectrum of methyl propanoate. How to explain the H-1 NMR spectrum of
methyl propanoate. The chemical shifts and integrated values of the proton ratios in the 1-H NMR
spectrum of the methyl propanoate molecule. How to work out the molecular
structure of the methyl propanoate molecule from its proton NMR spectrum. The uses
and distinctive features of the proton NMR spectrum of the methyl
propanoate
molecule explained. What does the H-1 proton NMR spectrum chemical
shifts tell us about the
structure and properties of the methyl propanoate
molecule? explaining the spin-spin proton coupling effects in the 1H
NMR spectrum of methyl propanoate. interpretation
diagram explaining the proton splitting
pattern produced from the n+1 rule and the theoretical ratio of chemical shift
δ and values of
intensities for the proton NMR spectrum lines of methyl propanoate
Links associated
with
methyl propanoate
The infrared spectrum of methyl
propanoate (methyl propionate)
The mass spectrum of methyl propanoate
(methyl propionate)
The C-13
NMR spectrum of methyl propanoate (methyl propionate)
The chemistry of CARBOXYLIC ACIDS and DERIVATIVES
revision notes INDEX
H-1 proton NMR spectroscopy index
(Please
read 8 points at the top of the 1H NMR index page)
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