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Interpreting
and explaining the
H-1 hydrogen-1 NMR spectrum of butanoic acid
(butyric acid)
[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
spectrometry - analysing the 1H NMR spectra of
butanoic acid
[spectra page updated
April 3rd 2026 *]
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1H NMR spectrum of CH3CH2CH2COOH
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H-1 proton NMR spectroscopy -
spectra index
Introductory note on the 1H NMR spectra of butanoic acid
Students and teachers please note my explanation of the
proton NMR spectrum of butanoic acid is designed for advanced, but
pre-university, chemistry courses.
The chemical shift
δ splitting pattern effects for
butanoic acid 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
butanoic acid 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 butanoic acid molecule.
The most common solvent used for investigating the 1H NMR
spectrum of compounds like butanoic acid, 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 - butanoic acid here.
The chemical shifts quoted in ppm on the diagram of
the H-1 NMR spectrum of butanoic acid 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 butanoic acid molecule.
Butanoic acid
(butyric acid)
a carboxylic acid,
see
The molecular structure and naming of carboxylic
acids and derivatives
Interpreting the
H-1 NMR spectrum of
butanoic acid
In terms of spin-spin coupling from the possible proton magnetic orientations,
for butanoic acid I
have only considered the interactions of
non-equivalent protons on adjacent carbon atoms
e.g. -CH2-CH3,
R-CH2-CH2-X.
For relatively simple molecules, the low
resolution H-1 NMR spectrum of butanoic acid is a good
starting point (high resolution diagram above, but just 'blur'
the groups of lines into integrated
proton ratio of 3:2:2:1).
The hydrogen atoms (protons) of butanoic acid occupy
4
different chemical environments so that the low resolution NMR
spectra should show 4 principal
1H peaks of different H-1 NMR chemical shifts (diagram above for
butanoic acid).
CH3CH2CH2COOH
Note the proton ratio
3:2:2:1 of the 4 colours of the protons
in the 4 chemically different proton environments
Chemical shifts (a) to (d) on the H-1 NMR
spectrum diagram for butanoic acid.
The integrated signal proton ratio
3:2:2:1 observed
in the high resolution H-1 NMR spectrum, corresponds with
the structural formula of butanoic acid.
The high resolution 1H NMR
spectrum of butanoic acid
All low and high resolution spectra of butanoic
acid
show 4 groups of proton resonances and in the 3:2:2:1 ratio expected from the
structural
formula of butanoic acid.
The ppm quoted on the diagram represent the peak
of resonance intensity for a particular proton group in the
molecule of butanoic acid - 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 butanoic acid below.
So, using the chemical shifts and applying the
n+1 rule to
butanoic acid
and make some predictions using some colour coding! (In problem
solving you work the other way round!)
(a) 1H
Chemical shift 0.98 ppm, methyl protons: CH3CH2CH2COOH
This 1H resonance is split by the
adjacent CH2 protons into a 1:2:1 triplet
(n+1 = 3)
Evidence for the presence of a CH2 group
in the molecule of butanoic acid
(b) 1H
Chemical shift 1.68ppm, CH2 protons: CH3CH2CH2COOH
This 1H resonance is split by the
adjacent CH2 and CH3 protons into a
1:5:10:10:5:1 sextet (n+5 = 6)
Evidence for the presence of a CH3-CHx-CH3 group
in the molecule of butanoic acid
(c) 1H
Chemical shift 2.33 ppm, CH2 protons: CH3CH2CH2COOH
This 1H resonance is split by the
adjacent CH2 protons into a 1:2:1 triplet
(n+1 = 3)
Evidence for the presence of a 2nd CH2 group
in the molecule of butanoic acid
(d) 1H
Chemical shift 11.5 ppm, hydroxyl proton: CH3CH2CH2COOH
This resonance is NOT split, there is no
proton on an adjacent atom.
Evidence for the presence of an isolated
proton
in the molecule of butanoic acid
Note the decreasing effect on the 1H chemical shift as the
proton is further from the more electronegative oxygen atoms in butanoic
acid.
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
butanoic acid.
|
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
CH3CH2CH2COOH Interpreting the proton H-1 NMR spectra of butanoic acid, low resolution & high resolution proton
nmr spectra of butanoic acid, H-1 nmr spectrum of butanoic acid, understanding the
hydrogen-1 nmr spectrum of butanoic acid, explaining the line splitting patterns from
spin-spin coupling in the
high resolution H-1 nmr spectra of butanoic acid, revising the H-1 nmr spectrum of
butanoic acid,
proton nmr of butanoic acid, ppm chemical shifts of the H-1 nmr spectrum of
butanoic acid,
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 butanoic acid, how to work out the
number of chemically different protons in the structure of the butanoic acid organic
molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR
spectrum of butanoic acid using the n+1 rule to explain the spin - spin coupling ine
splitting in the proton nmr spectrum of butanoic acid deducing the nature of the protons
from the chemical shifts ppm in the H-1 nmr spectrum of butanoic acid
examining the 1H nmr spectrum of butanoic acid analysing the 1-H nmr spectrum of
butanoic acid
how do you sketch and interpret the H-1 NMR spectrum of butanoic acid
interpreting interpretation of the 1H proton spin-spin coupling causing line
splitting in the NMR spectrum of butanoic acid
assignment of chemical shifts in the
proton 1H NMR spectrum of butanoic acid formula explaining spin-spin coupling for line splitting
for type functional group
butyric acid
carboxylic acid
C4H8O2
CH3CH2CH2COOH How do you interpret the H-1 NMR spectrum of
butanoic acid How to interpret
the H-1 NMR spectrum of butanoic acid Explanatory diagram of the chemical
shifts of the 1H H-1 proton NMR spectrum of the butanoic acid
molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the
proton NMR spectrum of butanoic acid. How to explain the H-1 NMR spectrum of
butanoic acid. The chemical shifts and integrated values of the proton ratios in the 1-H NMR
spectrum of the butanoic acid molecule. How to work out the molecular
structure of the butanoic acid molecule from its proton NMR spectrum. The uses
and distinctive features of the proton NMR spectrum of the butanoic
acid
molecule explained. What does the H-1 proton NMR spectrum chemical
shifts tell us about the
structure and properties of the butanoic acid
molecule? explaining the spin-spin proton coupling effects in the 1H
NMR spectrum of butanoic acid. 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 butanoic acid
Links associated
with
butanoic acid
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)
The infrared spectrum of
butanoic acid
The mass spectrum of butanoic acid
The 13C carbon-13 NMR
spectrum of butanoic acid
ALL SPECTROSCOPY INDEXES
All Advanced Organic
Chemistry Notes
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