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Interpreting the
1H
hydrogen-1 (proton) NMR spectrum of 2-methylhexane
[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 spectrum of
2-methylhexane
[spectra
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Mar 13th 2026 *]
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CH3CH2CH2CH2CH(CH3)2
Links associated
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H-1 proton NMR spectroscopy -
spectra index
See also
comparing the
1H NMR and 13C NMR spectra of the nine alkane structural isomers of C7H16
Introductory note on the 1H NMR spectra of 2-methylhexane
Students and teachers please note my explanation of the
proton NMR spectrum of 2-methylhexane is designed for advanced, but
pre-university, chemistry courses.
The chemical shift
δ splitting pattern effects for
2-methylhexane 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
2-methylhexane 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 2-methylhexane molecule.
The most common solvent used for investigating the 1H NMR
spectrum of compounds like 2-methylhexane, 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 - 2-methylhexane here.
The chemical shifts quoted in ppm on the diagram of
the H-1 NMR spectrum of 2-methylhexane 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 2-methylhexane molecule.
2-methylhexane C7H16
The molecular structure and
naming of alkanes
Interpreting the
H-1 NMR spectrum of
2-methylhexane
For relatively simple molecules, the low
resolution H-1 NMR spectrum of 2-methylhexane is may or may
not be a good starting point
(low resolution diagram above).
You can observe three main peaks, but two
include resonances that overlap each other.
Theoretically, the hydrogen atoms (protons) of 2-methylhexane occupy
6 different chemical environments so that a very high resolution NMR
spectra should show 6 peaks of different H-1 NMR chemical shifts (diagram above for
2-methylhexane).
(CH3)2CHCH2CH2CH2CH3
Note that from the structure of 2-methylhexane
and theory, the proton ratio in the spectrum should be 6:1:2:2:2:3 of the
6 colours of the protons
in the 6 chemically different environments
Chemical shifts
(a) to (f) on the H-1 NMR
spectrum diagram for 2-methylhexane.
Although there are 16 hydrogen atoms in the molecule,
there are only 6 possible different chemical
environments for the hydrogen atoms in 2-methylhexane molecule.
The two 'left-hand' methyl groups include
six equivalent protons.
However, because several resonances
are close together you seem to observe ...
a ratio of 1:6:9 applied to the proton ratio
of the groups 1 x CH : 3 x CH2 : 3 x CH3
The high resolution 1H NMR
spectrum of 2-methylhexane
This is problematical because of the close
proximity of several of the chemical shifts.
The ppm quoted on the diagram represent the peak
of resonance intensity for a particular proton group in the
molecule of 2-methylhexane - 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 2-methylhexane below.
So, using the chemical shifts and applying the
n+1 rule to
2-methylhexane
and make some predictions using some colour coding! (In problem
solving you work the other way round!)
However, whatever the theory, you need very
high resolution to fully sort out the 1H NMR resonances for
2-methylhexane.
(a) 1H
Chemical shift 0.87, resonance for the C(CH3)2
groups of protons
(CH3)2CHCH2CH2CH2CH3
Theoretically this resonance would be
split into a 1:1 doublet by the CH proton (n+1 = 2). All
six protons of theses two methyl groups are equivalent
to each other i.e. give identical chemical shifts a
(0.87 ppm) because they occupy identical chemical
environments.
Evidence for the presence of a -CH- group
in the molecule of 2-methylhexane
(b) 1H
Chemical shift 1.52 ppm, resonance for the CH proton
(CH3)2CHCH2CH2CH2CH3
Theoretically this resonance would be
split into a nonet by the 2 x CH3 and CH2
protons on either side (n+8 = 9).
(c)
1H
Chemical shift 1.17 ppm, resonance for the 1st CH2 group
(left to right)
(CH3)2CHCH2CH2CH2CH3
Theoretically this resonance would be
split into a 1:3:3:1 quartet by the CH and CH2
protons on either side (n+3 = 4).
(d) 1H
Chemical shift 1.27 ppm, resonance for the 2nd CH2 group
(left to right)
(CH3)2CHCH2CH2CH2CH3
Theoretically this resonance would also
be split into a quintet by the CH2 protons on
either side (n+4 = 5).
(e) 1H
Chemical shift 1.27 ppm, resonance for the 3rd CH2 group
(left to right)
(CH3)2CHCH2CH2CH2CH3
Theoretically this resonance would also
be split into a sextet by the CH2 and CH3
protons on either side (n+5 = 6).
(f) 1H Chemical shift 0.89 ppm,
resonance for the right-hand end methyl group protons
(CH3)2CHCH2CH2CH2CH3
Theoretically this resonance would be
split into a 1:2:1 triplet by the CH2 protons
on left (n+2 = 3).
High-Resolution ¹H NMR Spectrum of 2-Methylhexane
2-Methylhexane (C7H16) contains 16
protons distributed across methyl (CH3), methylene (CH2), and
methine (CH) groups.
Due to its branched
structure, some environments that appear equivalent at low
resolution are magnetically non-equivalent at high
resolution.
|
Chemical Shift (δ, ppm) |
Proton Type |
Environment |
Integration |
Notes |
| ~0.90,
0.89 ppm |
CH3 |
Terminal methyl (–CH3) |
3H |
Triplet; adjacent to CH2 |
| ~0.92,
1.17 ppm |
CH2 |
Internal methylene (–CH2–) |
2H |
Slightly different due to
branching |
| ~1.00,
0.87 ppm |
CH3 |
Branched methyl (–C(CH3)2) |
6H |
Doublet; coupled to methine |
| ~1.30,
1.27 ppm |
CH2 |
Internal methylene (–CH2–) |
2H |
Multiplet; central chain |
| ~1.40,
1.27 ppm |
CH2 |
Near branch point |
2H |
Slightly deshielded |
| ~1.55,
1.52 ppm |
CH |
Methine (–CH–) at branch |
1H |
Multiplet; coupled to two CH3
groups |
Why Six
Peaks at high resolution?
- Diastereotopic methyl
groups: The two
terminal CH₃ groups are not chemically equivalent due to the
asymmetric branching at C2.
- Subtle shielding
differences: Even CH₂
groups in similar positions can differ slightly in chemical shift
due to 3D spatial effects.
- Methine proton:
Unique environment at the branch point, coupling to two methyl
groups.
Common
Misconceptions
- Assuming symmetry in
branched alkanes:
Students often treat terminal methyls as equivalent, missing subtle
differences.
- Overlooking resolution
limits:
Lower-resolution spectra may merge peaks, masking fine distinctions.
- Ignoring integration clues:
Misassigning peaks due to incorrect proton counts.
Exam
Revision Tips (AQA, Edexcel, OCR, WJEC, CCEA, CIE, IB, AP)
What to Focus On
- Integration:
Use peak areas to match proton counts.
- Chemical shift ranges:
Know alkyl (0.9–1.6 ppm), alkene, aromatic, and aldehyde regions.
- Multiplicity:
Apply n+1 rule carefully, especially in branched systems.
Strategy Tips
- Draw the molecule:
Identify all unique proton environments.
- Label protons:
Assign shifts based on proximity and symmetry.
- Compare isomers:
Practice with hexane versus 2-methylhexane vs. 3-methylhexane.
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
2-methylhexane.
|
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 |
|
Comparing the
1H NMR and 13C NMR spectra of the nine alkane structural isomers of C7H16
You can distinguish all 9 isomers from a data combination of their number of
1H NMR
chemical shifts,
and their resulting integrated 1H proton ratios, plus, their number of
13C
chemical shifts. |
|
Name of the alkane structural isomer of molecular
formula C7H16 |
Abbreviated structural formulae
of the nine isomers of molecular formula C7H16 (interpretation complications with 3-methylhexane and
2,3-dimethylpentane because they exhibit R/S isomerism due to a
chiral carbon) |
Skeletal formula of the
nine
alkane isomers of
molecular formula C7H16 |
Number of 1H NMR chemical shifts (δ) and
proton ratio (links
to spectrum) |
Number of 13C chemical shifts (δ)
(links
to spectrum) |
|
heptane |
 |
 |
4 δ: proton ratio: 3:2:2:1 (6:4:4:2 in the molecule) |
4 δ shifts |
|
2-methylhexane |
|
|
6 δ: proton ratio :
6:3:2:2:2:1 |
6 δ shifts |
|
3-methylhexane |
 |
 |
7 δ: proton ratio:
3:3:3:2:2:2:1 (simplification) !! |
7
δ shifts |
|
3-ethylpentane |
 |
 |
3 δ: proton ratio:
9:6:1 |
3 δ
shifts |
|
2,2-dimethylpentane |
 |
 |
4 δ: proton ratio:
9:3:2:2 |
5 δ shifts |
|
2,3-dimethylpentane |
 |
 |
6 δ: proton ratio:
6:3:3:2:1:1 (simplification) !! |
6 δ
shifts (simplification) !!! |
|
2,4-dimethylpentane |
 |
 |
3 δ: proton ratio:
12:2:2 |
3 δ
shifts |
|
3,3-dimethylpentane |
 |
 |
3 δ: proton ratio:
3:3:2 (6:4:4 in the molecule) |
4 δ
shifts |
|
2,2,3-trimethylbutane |
 |
 |
3 δ: proton ratio:
9:6:1 |
4 δ shifts |
Key words & phrases:
C7H16
Interpreting the proton H-1 NMR spectra of 2-methylhexane, low resolution & high resolution proton
nmr spectra of 2-methylhexane, H-1 nmr spectrum of 2-methylhexane, understanding the
hydrogen-1 nmr spectrum of 2-methylhexane, explaining the line splitting patterns in the
high resolution H-1 nmr spectra of 2-methylhexane, revising the H-1 nmr spectrum of
2-methylhexane,
proton nmr of 2-methylhexane, ppm chemical shifts of the H-1 nmr spectrum of
2-methylhexane,
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 2-methylhexane, how to work out the
number of chemically different protons in the structure of the 2-methylhexane organic
molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR
spectrum of 2-methylhexane using the n+1 rule to explain the spin - spin coupling ine
splitting in the proton nmr spectrum of 2-methylhexane deducing the nature of the protons
from the chemical shifts ppm in the H-1 nmr spectrum of 2-methylhexane
examining the 1H nmr spectrum of 2-methylhexane analysing the 1-H nmr spectrum of
2-methylhexane how do you sketch and interpret the H-1 NMR spectrum of
2-methylhexane
interpreting interpretation of the 1H proton NMR spectrum of 2-methylhexane
(CH3)2CHCH2CH2CH2CH3
Molecular structure diagram of the
proton NMR diagram for the 1H NMR spectrum of 2-methylhexane. The proton ratio in the
1H NMR spectrum of 2-methylhexane. Deducing the number of different chemical
environments of the protons in the 2-methylhexane molecule from the 1H chemical shifts
in the hydrogen-1 NMR spectrum of 2-methylhexane. Analysing the high resolution 1H NMR
spectrum of 2-methylhexane. Analysing the low resolution 1H NMR spectrum of
2-methylhexane. You
may need to know the relative molecular mass of 2-methylhexane to deduce the molecular
formula from the proton ratio of the 1H NMR spectrum of 2-methylhexane. Revision notes
on the proton NMR spectrum of 2-methylhexane. Matching and deducing the structure of
the 2-methylhexane molecule from its hydrogen-1 NMR spectrum.
Proton NMR spectroscopy of aliphatic alkanes,
1H NMR spectra of 2-methylhexane, a structural isomer of molecular formula
C7H16
How do you interpret the H-1 NMR spectrum of
2-methylhexane How to interpret
the H-1 NMR spectrum of 2-methylhexane Explanatory diagram of the chemical
shifts of the 1H H-1 proton NMR spectrum of the 2-methylhexane
molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the
proton NMR spectrum of 2-methylhexane. How to explain the H-1 NMR spectrum of
2-methylhexane. The chemical shifts and integrated values of the proton ratios in the 1-H NMR
spectrum of the 2-methylhexane molecule. How to work out the molecular
structure of the 2-methylhexane molecule from its proton NMR spectrum. The uses
and distinctive features of the proton NMR spectrum of the
2-methylhexane
molecule explained. What does the H-1 proton NMR spectrum chemical
shifts tell us about the
structure and properties of the 2-methylhexane
molecule? explaining the spin-spin proton coupling effects in the 1H
NMR spectrum of 2-methylhexane.
diagram explaining the proton splitting
pattern produced from the n+1 rule and the theoretical ratio of chemical shift
and values of intensities for the proton NMR spectrum lines of 2-methylhexane
Links associated
with
2-methylhexane
The
infrared spectrum of 2-methylhexane
The mass
spectrum of 2-methyhexane
The
C-13 NMR spectrum of 2-methylhexane
The chemistry of ALKANES
revision notes INDEX
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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TOP OF PAGE
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Infrared spectra of the isomers of C7H16
The infrared
spectrum of heptane
The
infrared spectrum of 2-methylhexane
The
infrared spectrum of 3-methylhexane
The
infrared spectrum of 3-ethylpentane
The infrared spectrum of
2,2-dimethylpentane
The infrared spectrum of
2,3-dimethylpentane
The infrared spectrum of
2,4-dimethylpentane
The infrared spectrum of
3,3-dimethylpentane
The infrared spectrum
of 2,2,3-trimethylbutane
|
Mass spectra of the isomers of C7H16
The mass
spectrum of heptane
The mass
spectrum of 2-methylhexane
The mass
spectrum of 3-methylhexane
The
mass spectrum of 3-ethylpentane
The mass spectrum of
2,2-dimethylpentane
The mass spectrum of
2,3-dimethylpentane
The mass spectrum of
2,4-dimethylpentane
The mass spectrum of
3,3-dimethylpentane
The mass
spectrum of 2,2,3-trimethylbutane
|
|
H-1 proton NMR spectra of ALKANES
1H NMR spectra of the isomers of C7H16
The H-1 NMR
spectrum of heptane
The
H-1 NMR spectrum of 2-methylhexane
The
H-1 NMR spectrum of 3-methylhexane
The
H-1 NMR spectrum of 3-ethylpentane
The H-1 NMR spectrum of
2,2-dimethylpentane
The H-1 NMR spectrum of
2,3-dimethylpentane
The H-1 NMR spectrum of
2,4-dimethylpentane
The H-1 NMR spectrum of
3,3-dimethylpentane
The H-1
NMR spectrum of 2,2,3-trimethylbutane
|
C-13 carbon-13 NMR spectra
of ALKANES
13C NMR spectra of the isomers of C7H16
The C-13 NMR
spectrum of heptane
The
C-13 NMR spectrum of 2-methylhexane
The
C-13 NMR spectrum of 3-methylhexane
The
C-13 NMR spectrum of 3-ethylpentane
The C-13 NMR spectrum of
2,2-dimethylpentane
The C-13 NMR spectrum of
2,3-dimethylpentane
The C-13 NMR spectrum of
2,4-dimethylpentane
The C-13 NMR spectrum of
3,3-dimethylpentane
The
C-13 NMR spectrum of 2,2,3-trimethylbutane
|
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