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Interpreting and
explaining the H-1
(proton) NMR spectrum of hexane
[Author
©
Dr Phil Brown PhD:
Doc Brown's advanced level organic chemistry exam revision notes
suitable for students of UK A level chemistry courses,
IB chemistry & US K12 grade 11,
grade 12 and AP honors chemistry courses:
Molecular spectroscopy
analysis of
hexane
[spectrum page
updated Mar 24th 2026 *]
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1H spectrum of
CH3(CH2)4CH3
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H-1
proton NMR spectroscopy - spectra index
See also
comparing infrared, mass, 1H NMR & 13C NMR
spectra of the structural alkane isomers of C6H14
and details of the
Isomers of molecular formula C6H14
(Mr = 86)
Introductory note on the 1H NMR spectra of hexane
Students and teachers please note my explanation of the
proton NMR spectrum of hexane is designed for advanced, but
pre-university, chemistry courses.
The chemical shift
δ splitting pattern effects for
hexane 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
hexane molecule).
It is assumed that the integrated intensities of the
1H
NMR δ
chemical shifts give the ratio of the protons in the different
non-equivalent chemical environments of the hexane molecule.
The most common solvent used for investigating the 1H NMR
spectrum of compounds like hexane, is CDCl3 and other
deuterated solvents to avoid confusion with a 1H NMR
signal, 2D (2H) has a different NMR 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 shifts, called chemical shifts, depend on the
individual (electronic) chemical environment of the hydrogen atoms
in an organic molecule - hexane here.
The chemical shifts quoted in ppm on the diagram of
the H-1 NMR spectrum of hexane 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 hexane molecule.
Hexane C6H14,
,
,
an alkane
For more
see The molecular structure,
classification and
naming of alkanes
Interpreting the
H-1 NMR spectrum of
hexane
For relatively simple molecules, the low
resolution H-1 NMR spectrum of hexane is a good starting point
(low resolution diagram above).
The hydrogen atoms (protons) of hexane occupy
3
different chemical environments so that the low resolution NMR
spectra should show 3 peaks of different H-1 NMR chemical shifts (diagram above for
hexane).
CH3CH2CH2CH2CH2CH3
Note the ratio
3:2:2 of the three colours of the protons
in the three chemically different environments
Although there are 14 hydrogen atoms in the molecule,
there only 3 possible chemical
environments for the hydrogen atoms in hexane molecule.
The integrated signal proton ratio
from the molecular structure
6:4:4 =
the 3:2:2 proton ratio observed, and corresponds with
the structural formula of hexane shown above.
The high resolution H-1 NMR
spectrum of hexane
In terms of spin-spin coupling from the possible proton magnetic orientations,
for hexane I
have only considered the interactions of
non-equivalent protons on adjacent carbon atoms
e.g. -CH2-CH3, -CH-CH2- protons
etc.
All low and high resolution spectra of hexane
show 3 groups of protons and in the ratio expected from the
formula of hexane.
The ppm quoted on the diagram represent the peak
of resonance intensity for a particular proton group in the
molecule of hexane - 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 hexane below.
So, using the chemical shifts and applying the
n+1 rule
to hexane
δ (a)
1H Chemical shift 0.89 ppm for
the 2 x CH3
protons
CH3CH2CH2CH2CH2CH3
The CH3 proton resonance is
split into a 1:2:1 triplet by the adjacent CH2
protons, (n+1 = 3).
Evidence for the presence of a CH2 group
in the molecule of hexane
δ (b)
1H Chemical shift 1.29 ppm for
the 2 x 'outer' CH2
protons
CH3CH2CH2CH2CH2CH3
This CH2 proton resonance is
split into a 1:5:10:10:5:1 sextet by the CH3
and CH2 protons on either side (n+1 = 6)
Evidence for the presence of a CH3CH2CH2 group
in the molecule of hexane
δ (c)
1H Chemical shift 1.27 ppm for
the 2 x 'central' CH2
protons
CH3CH2CH2CH2CH2CH3
At first sight you would think this CH2 proton resonance is
split into a 1:4:6:4:1 quintet by the CH2 and
CH2 protons on either side (n+1 = 5).
However, theoretically, these particular
pairs of CH2 proton pairs are equivalent to each
other due to their central symmetry in the symmetrical
hexane molecule and their 1H proton fields should not split each other's
resonance.
Therefore, theoretically, this resonance
is just split by one the adjacent groups of CH2 protons
into a 1:2:1 triplet (n+1 = 3).
Very high resolution is needed to sort
out the
two CH2 resonances because the chemical
shifts are so close together.
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Comparing the infrared, mass, 1H NMR and 13C NMR
spectra of the five structural alkane isomers of C6H14
NOTE: The images are linked to their
original detailed spectral analysis pages AND can be doubled in
size with touch screens to
increase the definition to the original hexane,
2-methylpentane, 3-methylpentane, 2,2-dimethylbutane and
2,3-dimethylbutane image sizes. These five molecules
are structural isomers of saturated alkanes of molecular formula C6H14
and
exemplify the infrared, mass, 1H NMR and 13C NMR spectra of lower
aliphatic alkanes (non-cyclic alkanes). |
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Infrared spectra below. |
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INFRARED SPECTRA:
Apart from the significant differences in the fingerprint region at
wavenumbers 1500 to 400 cm-1, there are no other
great striking differences, but each could be identified from
its infrared spectrum.
All the absorption
bands are typical of molecules containing saturated alkyl structure and
there are no characteristic infrared absorptions due to a specific
functional group. |
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Infrared spectra above, mass spectra below. |
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MASS SPECTRA: Base ion
peaks plus m/z comments.
Hexane: m/z 57, 42 and 56 prominent
2-methylpentane: m/z 43, 42 and 71 prominent
3-methylpentane: m/z 57, 41 and 56 prominent
2,2-dimethylbutane: m/z 43, 41, 57 and 71
prominent
2,3-dimethylbutane: m/z 43, 41, 42 and 71
prominent |
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Mass spectra above, 1H NMR spectra below. |
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1H NMR SPECTRA: They can
all be distinguished by their different integrated proton ratios -
need very high resolution.
Hexane:
3 1H
δ shifts, H ratio 3:2:2 (6:4:4 in formula)
2-methylpentane:
5 1H
δ shifts, H ratio 6:3:2:2:1
3-methylpentane:
4 1H
δ shifts, H ratio 6:4:3:1
2,2-dimethylbutane: 3 1H
δ shifts, H ratio 9:3:2
2,3-dimethylbutane: 2 1H
δ shifts, H ratio 6:1 (12:2 in formula) |
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1H NMR spectra above, 13C NMR spectra below. |
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13C NMR SPECTRA: From the
number of shifts, you can't distinguish (iii) and (iv) but you can
distinguish them from (i), (ii) and (v). (i) Hexane: 3 13C
δ shifts
(ii) 2-methylpentane: 5 13C
δ shifts
(iii) 3-methylpentane: 4 13C
δ shifts
(iv) 2,2-dimethylbutane: 4 13C
δ shifts
(v) 2,3-dimethylbutane: 2 13C
δ shifts |
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13C NMR spectra above. |
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).
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Number of protons 1H
causing splitting |
Splitting pattern produced from the
n+1 rule and the theoretical ratio of line intensities |
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0
means no splitting |
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1 |
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1
creates a doublet |
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1 |
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1 |
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2
creates a triplet |
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1 |
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2 |
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1 |
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3
creates a quartet |
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1 |
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3 |
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3 |
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1 |
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4
creates a quintet |
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1 |
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4 |
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6 |
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4 |
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1 |
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5
creates a sextet |
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1 |
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5 |
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10 |
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10 |
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5 |
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1 |
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6
creates a septet |
1 |
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6 |
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15 |
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20 |
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15 |
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6 |
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1 |
Key words & phrases: Interpreting the proton H-1 NMR spectra of hexane, low resolution & high resolution proton
nmr spectra of hexane, H-1 nmr spectrum of hexane, understanding the
hydrogen-1 nmr spectrum of hexane, explaining the line splitting patterns in the
high resolution H-1 nmr spectra of hexane, revising the H-1 nmr spectrum of
hexane,
proton nmr of hexane, ppm chemical shifts of the H-1 nmr spectrum of hexane,
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 hexane, how to work out the
number of chemically different protons in the structure of the hexane organic
molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR
spectrum of hexane using the n+1 rule to explain the spin - spin coupling ine
splitting in the proton nmr spectrum of hexane deducing the nature of the protons
from the chemical shifts ppm in the H-1 nmr spectrum of hexane
examining the 1H nmr spectrum of hexane analysing the 1-H nmr spectrum of
hexane how do you sketch and interpret the H-1 NMR spectrum of hexane
interpreting interpretation of the H-1 proton NMR spectrum of hexane
Molecular structure diagram of the
proton NMR diagram for the 1H NMR spectrum of hexane. The proton ratio in the
1H NMR spectrum of hexane. Deducing the number of different chemical
environments of the protons in the hexane molecule from the 1H chemical shifts
in the hydrogen-1 NMR spectrum of hexane. Analysing the high resolution 1H NMR
spectrum of hexane. Analysing the low resolution 1H NMR spectrum of hexane. You
may need to know the relative molecular mass of hexane to deduce the molecular
formula from the proton ratio of the 1H NMR spectrum of hexane. Revision notes
on the proton NMR spectrum of hexane. Matching and deducing the structure of
the hexane molecule from its hydrogen-1 NMR spectrum.
Proton NMR spectroscopy of aliphatic
alkanes,
1H NMR spectra of hexane, an isomer of molecular formula
C6H14
How do you interpret the H-1 NMR spectrum of hexane How to interpret
the H-1 NMR spectrum of hexane Explanatory diagram of the chemical
shifts of the 1H H-1 proton NMR spectrum of the hexane
molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the
proton NMR spectrum of hexane. How to explain the H-1 NMR spectrum of
hexane. The chemical shifts and integrated values of the proton ratios in the 1-H NMR
spectrum of the hexane molecule. How to work out the molecular
structure of the hexane molecule from its proton NMR spectrum. The uses
and distinctive features of the proton NMR spectrum of the hexane
molecule explained. What does the H-1 proton NMR spectrum chemical
shifts tell us about the
structure and properties of the hexane
molecule? explaining the spin-spin proton coupling effects in the 1H
NMR spectrum of hexane. 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 hexane
Links associated
with
hexane
The chemistry of ALKANES
revision notes INDEX
The infrared spectrum of hexane
The mass spectrum of hexane
The H-1 NMR spectrum of hexane
The C-13 NMR spectrum of hexane
H-1 proton NMR spectroscopy index
(Please
read 8 points at the top of the 1H NMR index page)
ALL SPECTROSCOPY INDEXES
All Advanced Organic
Chemistry Notes
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