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Interpreting the
13C1H NMR spectrum of 2,4-dimethylpentane
[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 & AP honors chemistry courses: Molecular
spectroscopy - analysing
1H NMR spectrum of
2,4-dimethylpentane
[spectra updated
Mar 19th 2026 *]
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1H NMR spectrum of
(CH3)2CHCH2CH(CH3)2
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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 2,4-dimethylpentane
Students and teachers please note my explanation of the
proton NMR spectrum of 2,4-dimethylpentane is designed for advanced, but
pre-university, chemistry courses.
The chemical shift
δ splitting pattern effects for
2,4-dimethylpentane 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
2,4-dimethylpentane 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 2,4-dimethylpentane molecule.
The most common solvent used for investigating the 1H NMR
spectrum of compounds like 2,4-dimethylpentane, 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 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 - 2,4-dimethylpentane here.
The chemical shifts quoted in ppm on the diagram of
the H-1 NMR spectrum of 2,4-dimethylpentane 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 2,4-dimethylpentane molecule.
2,4-dimethylpentane
C7H16
 
For more
see
The molecular structure,
classification and
naming of alkanes
Interpreting the
H-1 NMR spectrum of
2,4-dimethylpentane
For relatively simple molecules, the low
resolution H-1 NMR spectrum of 2,4-dimethylpentane is a good starting point
(low resolution diagram above).
At low resolution you observe an integrated
proton ratio of (2) : (2) : (12)
Theoretically, the 16 hydrogen atoms (protons) of
2,4-dimethylpentane occupy 3
different chemical environments so that the low or high resolution NMR
spectra should show 3 principal peaks of different H-1 NMR chemical shifts (diagram above for
2,4-dimethylpentane).
(CH3)2CHCH2CH(CH3)2
Note the
proton ratio 12:2:2 of the three colours of the protons
in the three chemically different environments
Chemical shifts
(a) to (c) on the H-1 NMR
spectrum diagram for 2,4-dimethylpentane.
Although there are 16 hydrogen atoms in the molecule,
there are only 3 possible different chemical
environments for the hydrogen atoms in 2,4-dimethylpentane molecule.
The integrated signal proton ratio 6:1:1 observed
in the high resolution H-1 NMR spectrum, corresponds with
the structural formula of 2,4-dimethylpentane.
The high resolution 1H NMR
spectrum of 2,4-dimethylpentane
The ppm quoted on the diagram represent the peak
of resonance intensity for a particular proton group in the
molecule of 2,4-dimethylpentane - 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 2,4-dimethylpentane below.
So, using the chemical shifts and applying the
n+1 rule to
2,4-dimethylpentane
and make some predictions using some colour coding! (In problem
solving you work the other way round!)
(a) 1H
Chemical shift 0.85 ppm, CH3 protons : (CH3)2CHCH2CH(CH3)2
The CH3 proton resonance line
is split into a doublet by the adjacent CH proton (n+1 =
2)
Evidence for the presence of a CH group
in the molecule of 2,4-dimethylpentane
(b) 1H
Chemical shift 1.62 ppm, CH protons: (CH3)2CHCH2CH(CH3)2
The CH proton resonance line is split
into a nonet by the adjacent 2 x CH3 and CH2
protons (n+8 = 1)
Evidence for the presence of a (CH3)2-C-CH2
grouping in the molecule of 2,4-dimethylpentane
(c) 1H
Chemical shift 1.03 ppm, CH2 protons : (CH3)2CHCH2CH(CH3)2
The CH2 proton resonance line
is split into a 1:2:1 triplet by the two adjacent CH
protons (n+1 = 3).
Evidence for the presence of a CH-C-CH
grouping in the molecule of 2,4-dimethylpentane
Key points about the
1H NMR spectrum of 2,4-dimethylpentane
The ¹H NMR spectrum of 2,4-dimethylpentane shows three distinct
chemical environments with signals around 0.9–1.2 ppm, reflecting
methyl and methylene protons in a branched alkane.
Integration and splitting patterns confirm the molecule’s symmetry
and lack of electronegative groups.
Overview:
¹H NMR of 2,4-Dimethylpentane
2,4-Dimethylpentane (C7H16)
is a highly symmetrical branched alkane. Its proton
NMR spectrum is simple, with no deshielding effects
from electronegative atoms or π systems. All signals appear in the
upfield region (0.8–1.2 ppm), typical of saturated
hydrocarbons.
Key Chemical Shifts and Proton
Environments for 2,4-dimethylpentane
|
Chemical Shift (δ, ppm) |
Proton Type |
Environment |
Integration |
Multiplicity |
Notes |
| ~0.90, 0.85 ppm |
CH3 |
Terminal methyl groups |
12H |
Singlet |
Six equivalent CH3
groups |
| ~1.00, 1.03 ppm |
CH2 |
Central methylene (C–CH2–C) |
2H |
Multiplet |
Coupled to adjacent CH groups |
| ~1.20, 1.62 ppm |
CH |
2 x methine (CH between CH2
and CH3) |
2H |
Multiplet |
Coupled to CH2
and CH3 |
Sources: SpectraBase and
https://sdbs.db.aist.go.jp/
diagram 1H
δ ppm
spectral database of organic compounds
Common
Misconceptions
| Misconception |
Clarification |
| "More carbon atoms mean more
NMR peaks." |
Not always—symmetry
reduces the number of distinct proton environments. |
| "All methyl groups give
separate signals." |
Only if they’re in
different environments—here, six CH3 groups
are equivalent. |
| "Alkanes show peaks above 2
ppm." |
Only if deshielded
by electronegative atoms or π systems—pure alkanes stay
below 1.5 ppm. |
| "Multiplicity always matches
number of adjacent protons." |
True in simple cases, but
overlapping signals and symmetry
can obscure splitting. |
Exam
Revision Tips
(AQA, Edexcel, OCR, WJEC, CCEA, CIE, IB, AP)
Interpretation Strategy
- Count signals:
Use symmetry to predict number of environments.
- Estimate integration:
Match peak areas to proton counts.
- Check multiplicity:
Use n+1 rule for adjacent protons.
- Use chemical shift:
Alkanes = 0.8–1.5 ppm; deshielded = higher ppm.
Typical
Board-Specific Tips
- Expect questions on
environment count, integration, and
splitting.
- May ask for assignment of
peaks to structure.
- Often integrates ¹H NMR
with IR/mass spec for full structure.
- : Focuses on pattern
recognition, symmetry, and signal
assignment.
Practice
Question: ¹H NMR Interpretation
A compound has the molecular
formula C7H16. Its ¹H NMR spectrum
shows:
- Three signals at δ = 0.90 ppm,
1.00 ppm, and 1.20 ppm
- Integration ratio of 12:2:2
- All signals appear as singlets
or simple multiplets
Q: Suggest a structure for
the compound and justify your answer using symmetry and proton
environments.
Model
Answer
Suggested structure:
2,4-dimethylpentane
Justification:
-
C7H16
matches a saturated hydrocarbon (alkane).
- Three signals
indicate three distinct proton environments,
implying symmetry.
- 12H at 0.90 ppm
= six equivalent CH3 groups (upfield, shielded).
- 2H at 1.00 ppm
= CH2 group between two CH groups.
- 2H at 1.20 ppm
= two equivalent CH groups flanked by CH3 and CH2.
- All chemical shifts are consistent
with alkyl protons in a branched alkane.
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).
|
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 2,4-dimethylpentane, low resolution & high resolution proton
nmr spectra of 2,4-dimethylpentane, H-1 nmr spectrum of 2,4-dimethylpentane, understanding the
hydrogen-1 nmr spectrum of 2,4-dimethylpentane, explaining the line splitting patterns in the
high resolution H-1 nmr spectra of 2,4-dimethylpentane, revising the H-1 nmr spectrum of
2,4-dimethylpentane,
proton nmr of 2,4-dimethylpentane, ppm chemical shifts of the H-1 nmr spectrum of
2,4-dimethylpentane,
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 2,4-dimethylpentane, how to work out the
number of chemically different protons in the structure of the
2,4-dimethylpentane organic
molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR
spectrum of 2,4-dimethylpentane using the n+1 rule to explain the spin - spin coupling
spin
splitting in the proton nmr spectrum of 2,4-dimethylpentane deducing the nature of the protons
from the chemical shifts ppm in the H-1 nmr spectrum of 2,4-dimethylpentane
examining the 1H nmr spectrum of 2,4-dimethylpentane analysing the 1-H nmr spectrum of
2,4-dimethylpentane how do you sketch and interpret the H-1 NMR spectrum of
2,4-dimethylpentane
interpreting interpretation of the 1H proton NMR spectrum of 2,4-dimethylpentane
(CH3)2CHCH2CH(CH3)2
Molecular structure diagram of the
proton NMR diagram for the 1H NMR spectrum of 2,4-dimethylpentane. The proton ratio in the
1H NMR spectrum of 2,4-dimethylpentane. Deducing the number of different chemical
environments of the protons in the 2,4-dimethylpentane molecule from the 1H chemical shifts
in the hydrogen-1 NMR spectrum of 2,4-dimethylpentane. Analysing the high resolution 1H NMR
spectrum of 2,4-dimethylpentane. Analysing the low resolution 1H NMR spectrum of
2,4-dimethylpentane. You
may need to know the relative molecular mass of 2,4-dimethylpentane to deduce the molecular
formula from the proton ratio of the 1H NMR spectrum of 2,4-dimethylpentane. Revision notes
on the proton NMR spectrum of 2,4-dimethylpentane. Matching and deducing the structure of
the 2,4-dimethylpentane molecule from its hydrogen-1 NMR spectrum.
Proton NMR spectroscopy of aliphatic alkanes,
1H NMR spectra of 2,4-dimethylpentane, a structural isomer of molecular formula
C7H16
How do you interpret the H-1 NMR spectrum of
2,4-dimethylpentane How to interpret
the H-1 NMR spectrum of 2,4-dimethylpentane Explanatory diagram of the chemical
shifts of the 1H H-1 proton NMR spectrum of the
2,4-dimethylpentane
molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the
proton NMR spectrum of 2,4-dimethylpentane. How to explain the H-1 NMR spectrum of
2,4-dimethylpentane. The chemical shifts and integrated values of the proton ratios in the 1-H NMR
spectrum of the 2,4-dimethylpentane molecule. How to work out the molecular
structure of the 2,4-dimethylpentane molecule from its proton NMR spectrum. The uses
and distinctive features of the proton NMR spectrum of the
2,4-dimethylpentane
molecule explained. What does the H-1 proton NMR spectrum chemical
shifts tell us about the
structure and properties of the 2,4-dimethylpentane
molecule? explaining the spin-spin proton coupling effects in the 1H
NMR spectrum of 2,4-dimethylpentane.
interpretation
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
2,4-dimethylpentane
Links associated
with
2,4-dimethylpentane
The infrared spectrum of
2,4-dimethylpentane
The mass spectrum of
2,4-dimethylpentane
The C-13 NMR spectrum of
2,4-dimethylpentane
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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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
|
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
|
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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