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Interpreting
and explaining the
H-1 hydrogen-1 (proton) NMR spectrum of cyclohexene
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©
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 cyclohexene
[spectra page updated
April 3rd 2026 *]
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1H NMR spectrum of
cyclo-C6H10
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H-1 proton NMR spectroscopy -
spectra index
Introductory note on the 1H NMR spectra of cyclohexene
Students and teachers please note my explanation of the
proton NMR spectrum of cyclohexene is designed for advanced, but
pre-university, chemistry courses.
The chemical shift
δ splitting pattern effects for
cyclohexene 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
cyclohexene 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 cyclohexene molecule.
The most common solvent used for investigating the 1H NMR
spectrum of compounds like cyclohexene, 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 - cyclohexene here.
The chemical shifts quoted in ppm on the diagram of
the H-1 NMR spectrum of cyclohexene 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 cyclohexene molecule.
cyclohexene
,
 ,
,
The molecular structure and naming of alkenes
Interpreting the
H-1 NMR spectrum of
cyclohexene
For relatively simple molecules, the low
resolution H-1 NMR spectrum of cyclohexene is a good starting point
(low resolution diagram above).
The 10 hydrogen atoms (protons) of cyclohexene occupy
3
different proton chemical environments so that the
low resolution NMR spectra should show
3 principal
1H resonance peaks of different H-1 NMR chemical shifts (diagram above for
cyclohexene).
Note the proton ratio
4:4 2
in the molecule of the 3 chemically different proton environments
Chemical shifts (a) to (c) on the H-1 NMR
spectrum diagram for cyclohexene.
Although there are 10 hydrogen atoms in the molecule, the
proton NMR spectrum shows there are only 3 possible different chemical
environments for the hydrogen atoms in cyclohexene molecule - due to the
symmetry of the hexagonal ring on either side of the C=C double bond.
The integrated proton signal ratio
observed as 2:2:1 observed
in the high resolution H-1 NMR spectrum, corresponds with
the structural formula of cyclohexene.
The high resolution 1H NMR spectrum of cyclohexene
In terms of spin-spin coupling from the possible proton magnetic orientations,
for cyclohexene I
have only considered the interactions of
non-equivalent protons on adjacent carbon atoms
e.g. -CH2-CH3, -CH-CH2-, protons
etc.
The high resolution spectra of cyclohexene
would show 3 groups of proton resonances and in the
integrated ration of
4:4:2 (2:2:1), as expected from the
structural
formula of cyclohexene, but we can now consider the splitting of
resonance lines from the spin-spin coupling in the molecule of
cyclohexene.
The ppm quoted on the diagram represent the peak
of resonance intensity for a particular proton group in the
molecule of cyclohexene - 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 cyclohexene below.
So, using the chemical shifts and applying the
n+1 rule to
cyclohexene
and make some predictions using some colour coding! (In problem
solving you work the other way round!)
1H NMR resonance
(a) 1H
Chemical shift δ 1.61 ppm:
The resonance for the 2 x CH2
protons furthest from the C=C bond.
This will be split into a triplet by the
CH2 protons nearer the C=C bond (n+2 = 3).
This resonance is not split by the other
CH2 protons furthest from the C=C bond
because they are adjacent and equivalent to each other
(the cyclohexene molecule is symmetrical about the -CH2-CH2-
grouping furthest from the C=C bond)..
1H NMR resonance
(b) 1H
Chemical shift δ 1.98 ppm:
The resonance for the 2 x CH2
protons nearest to the C=C bond.
This resonance will be split into a
quartet by the CH2 protons furthest from the
C=C bond and the CH proton of the C=C bond (n+1 = 4).
This proton resonance is similar to the
one above.
1H NMR resonance
(c) 1H
Chemical shift δ 5.66 ppm:
The resonance for the 2 x CH protons of
the C=C bond.
Here the presence of the pi orbitals of
the double bond results in a much greater 1H NMR
chemical shift than is
observed for the other four CH2 protons.
This resonance will be split into a
triplet by the CH2 protons nearest the C=C
bond (n+1 = 3).
This resonance is not split by the other
CH proton of the C=C bond because they are adjacent and
equivalent to each other (the cyclohexene molecule is
symmetrical about the -CH=CH-).
Key
revision points about the 1H NMR spectrum of cyclohexene
Key
Features of the ΉH NMR Spectrum of Cyclohexene
- Molecular formula:
C6H10 → 10 protons total.
- Distinct proton
environments: Four
sets of signals due to symmetry in the ring.
- Alkene protons (vinylic):
Deshielded, appear downfield (~5.66.0 ppm).
- Allylic protons (adjacent
to C=C): Slightly
deshielded, ~1.82.2 ppm.
- Remaining ring protons
(further from C=C):
More shielded, ~1.21.6 ppm.
- Splitting patterns:
Complex multiplets due to coupling in the ring system.
- Integration:
Matches the number of protons in each environment, summing to 10.
Table of
Chemical Shifts, Origins, and Integration for the 1H NMR spectrum of
cyclohexene
| δ
(ppm) range |
Proton type |
Origin |
Splitting
pattern |
Integration |
| 5.66.0,
5.66 |
=CH (vinylic) |
Two protons on the
double bond carbons |
Multiplet (coupling with
allylic protons) |
2H |
| 1.82.2,
1.98 |
Allylic CH2 |
Four protons
adjacent to C=C |
Multiplet |
4H |
| 1.21.6,
1.61 |
Ring CH2
(non‑allylic) |
Four protons
further from C=C |
Multiplet |
4H |
Spectra data source
https://sdbs.db.aist.go.jp/Disclaimer.aspx for
1H δ
ppm
Common
Student Misconceptions
- Expecting aromatic‑like
signals: Cyclohexene
is an alkene, not aromatic; signals are downfield but not in the 78
ppm region.
- Miscounting proton
environments: Students
sometimes expect six signals (one per carbon), but symmetry reduces
this to four distinct sets.
- Confusing allylic protons
with normal alkyl protons:
Allylic protons are shifted slightly downfield (~2 ppm), not at ~1
ppm like typical alkyl CH3.
- Overlooking integration
ratios: Integration
must add to 10 protons; missing this check leads to misassignments.
Exam
Revision Tips
- Always check integration:
Ensure total = 10 protons.
- Identify vinylic protons
(~5.66 ppm):
Diagnostic of alkenes.
- Look for allylic protons
(~2 ppm): Slightly
deshielded compared to normal alkyl.
- Compare with cyclohexane:
Cyclohexane shows only shielded protons (~1.2 ppm), no downfield
vinylic signals.
- Exam technique:
When asked to assign signals, state ppm, proton type, splitting, and
integration (e.g., Signal at ~5.7 ppm, multiplet, 2H, vinylic
protons on C=C).
- Cross‑board consistency:
All exam boards (AQA, Edexcel, OCR, WJEC, CCEA, CIE, IB, AP) expect
recognition of vinylic versus allylic protons and correct
integration.
Final
summary
For A level and AP exams,
focus on:
- Vinylic protons at ~5.66
ppm (2H).
- Allylic protons at ~2 ppm
(4H).
- Remaining ring protons at
~1.21.6 ppm (4H).
- Integration = 10 protons
total.
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
cyclohexene.
|
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:
isomer
of molecular formula C6H10
Interpreting the proton H-1 NMR spectra of cyclohexene, low resolution & high
resolution proton nmr spectra of cyclohexene, H-1 nmr spectrum of cyclohexene, understanding the
hydrogen-1 nmr spectrum of cyclohexene, explaining the line splitting patterns from
spin-spin coupling in the high resolution H-1 nmr spectra of cyclohexene, revising
the H-1 nmr spectrum of cyclohexene, proton nmr of cyclohexene, ppm chemical shifts of the H-1
nmr spectrum of cyclohexene, explaining and analyzing spin spin line splitting in the
H-1 nmr spectrum, how to construct the diagram of the 1H nmr spectrum of
cyclohexene, how to work out the
number of chemically different protons in the structure of the cyclohexene organic
molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR
spectrum of cyclohexene using the n+1 rule to explain the spin - spin coupling ine
splitting in the proton nmr spectrum of cyclohexene deducing the nature of the protons
from the chemical shifts ppm in the H-1 nmr spectrum of cyclohexene
examining the 1H nmr spectrum of cyclohexene analysing the 1H nmr spectrum of
cyclohexene
how do you sketch and interpret the H-1 NMR spectrum of cyclohexene interpreting
interpretation of the 1H proton spin-spin coupling causing line splitting in the
NMR spectrum of cyclohexene
assignment of chemical shifts in the
proton 1H NMR spectrum of cyclohexene formula explaining spin-spin coupling for
line splitting for cyclohexene
alkene
functional group How do you interpret the H-1 NMR spectrum of cyclohexene How to interpret the H-1 NMR spectrum of cyclohexene Explanatory diagram of the chemical shifts of the 1H H-1 proton NMR spectrum of the cyclohexene molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the proton NMR spectrum of cyclohexene. How to explain the H-1 NMR spectrum of cyclohexene. The chemical shifts and integrated values of the proton ratios in the 1-H NMR spectrum of the cyclohexene molecule. How to work out the molecular structure of the cyclohexene molecule from its proton NMR spectrum. The uses and distinctive features of the proton NMR spectrum of the cyclohexene molecule explained. What does the H-1 proton NMR spectrum chemical shifts tell us about the structure and properties of the cyclohexene molecule?
How do you interpret the H-1 NMR spectrum of
cyclohexene How to interpret
the H-1 NMR spectrum of cyclohexene Explanatory diagram of the chemical
shifts of the 1H H-1 proton NMR spectrum of the cyclohexene
molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the
proton NMR spectrum of cyclohexene. How to explain the H-1 NMR spectrum of
cyclohexene. The chemical shifts and integrated values of the proton ratios in the 1-H NMR
spectrum of the cyclohexene molecule. How to work out the molecular
structure of the cyclohexene molecule from its proton NMR spectrum. The uses
and distinctive features of the proton NMR spectrum of the
cyclohexene
molecule explained. What does the H-1 proton NMR spectrum chemical
shifts tell us about the
structure and properties of the cyclohexene
molecule? explaining the spin-spin proton coupling effects in the 1H
NMR spectrum of cyclohexene. 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 cyclohexene
Links associated with cyclohexene
The infrared spectrum of cyclohexene
The mass
spectrum of cyclohexene
The C-13 NMR spectrum of
cyclohexene
Isomers of molecular
formula C6H10
(Mr = 82)
The chemistry of ALKENES
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
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spectroscopy (1H NMR spectra of cyclohexene) are
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