|
Interpreting the H-1
hydrogen-1 (proton) NMR spectrum of heptane
[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 analysis of
heptane
[spectra page updated
Mar 24th 2026 *]
email doc
brown Re-edit
1H NMR spectrum
CH3(CH2)5CH3
Links associated with heptane
* [privacy policy, cookies
and disclaimer]
This is a BIG
website, PLEASE take time to explore it
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 heptane
Students and teachers please note my explanation of the
proton NMR spectrum of heptane is designed for advanced, but
pre-university, chemistry courses.
The chemical shift
δ splitting pattern effects for
heptane 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
heptane 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 heptane molecule.
The most common solvent used for investigating the 1H NMR
spectrum of compounds like heptane, 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 - heptane here.
The chemical shifts quoted in ppm on the diagram of
the H-1 NMR spectrum of heptane 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 heptane molecule.
Heptane,
C7H16 , CH3(CH2)5CH3
,
,
an alkane
For more
see The molecular structure,
classification and
naming of alkanes
Interpreting the
H-1 NMR spectrum of
heptane
For relatively simple molecules, the low
resolution H-1 NMR spectrum of heptane is a limited, but not
useless, starting point.
The hydrogen atoms (protons) of heptane occupy,
theoretically, 4
different chemical environments so that the very high resolution NMR
spectra should show 4 peaks of different
1H NMR chemical shifts (diagram above for
heptane), BUT three of the chemical shifts are very close
together, so even at moderate resolution (diagram above) you see
two main peaks in the proton ration 3:5 for CH3:CH2
protons..
CH3CH2CH2CH2CH2CH2CH3
Note the proton ratio 6:4:4:2 (3:2:2:1) of the
four colours of the protons
in the four chemically different environments, but, even a
moderate resolution spectrum (diagram above) shows two main
peaks in the ratio of 3:5 for the CH3:CH2
protons.
Chemical shifts
(a) to (d) on the H-1 NMR
spectrum diagram for heptane.
Although there are 16 hydrogen atoms in the molecule,
there are, theoretically, only 4 possible different chemical
environments for the hydrogen atoms in the symmetrical heptane molecule.
The high resolution 1H NMR
spectrum of heptane
All low and high resolution spectra of heptane
show 4 groups of proton resonances and in the 3:2:2:1 ratio expected from the
formula of heptane.
The ppm quoted on the diagram represent the peak
of resonance intensity for a particular proton group in the
molecule of heptane - 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 heptane below.
So, using the chemical shifts and applying the
n+1 rule to
heptane
and make some predictions using some colour coding! (In problem
solving you work the other way round!)
(a) 1H
Chemical shift 0.88 ppm, CH3 proton resonance, CH3CH2CH2CH2CH2CH2CH3
The CH3 proton resonance is
split into a 1:2:1 triplet by the neighbouring CH2
protons.
Evidence for the presence of a CH2
group in the molecule of heptane
(b) to (d) are very similar and would need very high resolution to
resolve the complex splitting patterns involved.
Resonances (a):(b) + (c)+(d) gives
a the
ratio 3:5 for the CH3:CH2 protons
(b) 1H
Chemical shift 1.30 ppm, CH2 proton resonance, CH3CH2CH2CH2CH2CH2CH3
Theoretically this resonance is split
into a sextet (n+1 = 6) by the neighbouring CH3
and CH2 protons.
(c) 1H
Chemical shift 1.27 ppm, CH2 proton resonance, CH3CH2CH2CH2CH2CH2CH3
Theoretically this resonance is split
into a quintet (n+1 = 5) by the neighbouring CH2
and CH2 protons on either side.
(d) 1H
Chemical shift 1.27 ppm, CH2 proton resonance, CH3CH2CH2CH2CH2CH2CH3
Theoretically this resonance is split
into a quintet (n+1 = 5) by the neighbouring CH2
and CH2 protons.
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 heptane, low resolution & high resolution proton
nmr spectra of heptane, H-1 nmr spectrum of heptane, understanding the
hydrogen-1 nmr spectrum of heptane, explaining the line splitting patterns in the
high resolution H-1 nmr spectra of heptane, revising the H-1 nmr spectrum of
heptane,
proton nmr of heptane, ppm chemical shifts of the H-1 nmr spectrum of heptane,
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 heptane, how to work out the
number of chemically different protons in the structure of the heptane organic
molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR
spectrum of heptane using the n+1 rule to explain the spin - spin coupling ine
splitting in the proton nmr spectrum of heptane deducing the nature of the protons
from the chemical shifts ppm in the H-1 nmr spectrum of heptane
examining the 1H nmr spectrum of heptane analysing the 1-H nmr spectrum of
heptane how do you sketch and interpret the H-1 NMR spectrum of heptane
interpreting interpretation of the 1H proton NMR spectrum of heptane
Molecular structure diagram of the
proton NMR diagram for the 1H NMR spectrum of heptane. The proton ratio in the
1H NMR spectrum of heptane. Deducing the number of different chemical
environments of the protons in the heptane molecule from the 1H chemical shifts
in the hydrogen-1 NMR spectrum of heptane. Analysing the high resolution 1H NMR
spectrum of heptane. Analysing the low resolution 1H NMR spectrum of heptane. You
may need to know the relative molecular mass of heptane to deduce the molecular
formula from the proton ratio of the 1H NMR spectrum of heptane. Revision notes
on the proton NMR spectrum of heptane. Matching and deducing the structure of
the heptane molecule from its hydrogen-1 NMR spectrum.
Proton NMR spectroscopy of aliphatic alkanes,
1H NMR spectra of heptane, a structural isomer of molecular formula
C7H16
How do you interpret the H-1 NMR spectrum of
heptane How to interpret
the H-1 NMR spectrum of heptane Explanatory diagram of the chemical
shifts of the 1H H-1 proton NMR spectrum of the heptane
molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the
proton NMR spectrum of heptane. How to explain the H-1 NMR spectrum of
heptane. The chemical shifts and integrated values of the proton ratios in the 1-H NMR
spectrum of the heptane molecule. How to work out the molecular
structure of the heptane molecule from its proton NMR spectrum. The uses
and distinctive features of the proton NMR spectrum of the heptane
molecule explained. What does the H-1 proton NMR spectrum chemical
shifts tell us about the
structure and properties of the heptane
molecule? explaining the spin-spin proton coupling effects in the 1H
NMR spectrum of heptane. 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 heptane
Links associated
with
heptane
The infrared
spectrum of heptane
The mass
spectrum of heptane
The C-13 NMR
spectrum of heptane
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
Use My Google search site box
Email doc b:
chem55555@hotmail.com
|
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
|
Website content © Dr
Phil Brown 2000+. All copyrights reserved on revision notes, images,
quizzes, worksheets etc. Copying of Doc Brown's pre-university
advanced level chemistry website material is NOT
permitted. Exam revision summaries & references to science course specifications
are unofficial. These organic chemistry revision notes on
spectroscopy are
suitable for use of pre-university students studying AQA advanced level
chemistry, Edexcel advanced level chemistry, OCR advanced level
chemistry, IB advanced level chemistry, WJEC (Eduqas) advanced level
chemistry, CIE advanced level chemistry, CCEA advanced level chemistry, US grade 11-12 AP honors
chemistry courses and they will also prove useful to
1st year undergraduate students of chemistry.
|
