|
Interpreting the
1H NMR spectrum of bromoethane
[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
of bromoethane
[spectra updated
Mar 19th 2026 *]
email doc
brown
Re-edit
1H NMR spectrum of
CH3CH2Br
Links associated with bromoethane
*
[privacy,
cookies & disclaimer policies]
This is a BIG
website, PLEASE take time to explore it
H-1 proton NMR spectroscopy -
spectra index
Introductory note on the 1H NMR spectra of bromoethane
Students and teachers please note my explanation of the
proton NMR spectrum of bromoethane is designed for advanced, but
pre-university, chemistry courses.
The chemical shift
δ splitting pattern effects for
bromoethane 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
bromoethane 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 bromoethane molecule.
The most common solvent used for investigating the 1H NMR
spectrum of compounds like bromoethane, 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 - bromoethane here.
The chemical shifts quoted in ppm on the diagram of
the H-1 NMR spectrum of bromoethane 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 bromoethane molecule.
Bromoethane 
The molecular structure and naming of haloalkanes
Interpreting the
H-1 NMR spectrum of
bromoethane
In terms of spin-spin coupling from the possible proton magnetic orientations,
for bromoethane I
have only considered the interactions of
non-equivalent protons on adjacent carbon atoms
e.g. -CH2-CH3.
For relatively simple molecules, the low
resolution H-1 NMR spectrum of bromoethane is a good starting point
with two obvious proton resonances.
The hydrogen atoms (protons) of bromoethane occupy
2
different chemical environments so that the low resolution NMR
spectra should show 2 principal peaks of different H-1 NMR chemical shifts (diagram above for
bromoethane).
CH3CH2Br
Note the proton ratio 3:2 of the two colours of the protons
in the two chemically different environments
Chemical shifts
(a) and (b) on the H-1 NMR
spectrum diagram for bromoethane.
Although there are 5 hydrogen atoms in the molecule,
there are only 2 possible different chemical
environments for the hydrogen atoms in bromoethane molecule.
The integrated signal
proton ratio of 3:2 observed
in the high resolution H-1 NMR spectrum, corresponds with
the structural formula of bromoethane.
The high resolution 1H NMR
spectrum of bromoethane
All low and high resolution spectra of
bromoethane
show 2 groups of proton resonances and in the 3:2 ratio expected from the
formula of bromoethane.
The ppm quoted on the diagram represent the peak
of resonance intensity for a particular proton group in the
molecule of bromoethane - 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 bromoethane below.
So, using the chemical shifts and applying the
n+1 rule to
bromoethane
and make some predictions using some colour coding! (In problem
solving you work the other way round!)
(a) 1H
Chemical shift 1.68 ppm, CH3 proton resonance: CH3CH2Br
This resonance is split into a 1:2:1
triplet by the CH2 protons (n+1 = 3).
Evidence for the presence of a CH2 group
in the molecule of bromoethane
(b) 1H
Chemical shift 3.43 ppm, CH2 proton resonance: CH3CH2Br
This resonance is split into a 1:3:3:1
quartet by the CH3 protons (n+1 = 4).
Evidence for the presence of a CH3 group
in the molecule of bromoethane
Note the decreasing effect on the chemical shift as the
hydrogen atom is further from the more electronegative bromine atom of bromoethane.
Comparing
the 1H and 13C NMR chemical shifts of bromoethane with other monosubstituted halogen derivatives of ethane
|
Compound |
fluoroethane |
chloroethane |
bromoethane |
iodoethane |
ethane |
|
Formula |
CH3CH2F |
CH3CH2Cl |
CH3CH2Br |
CH3CH2I |
CH3CH3 |
|
1H chemical
shift/ppm |
- |
1.49 and 3.51 |
1.68 and
3.43 |
1.85 and 3.19 |
0.74 |
|
13C
chemical shift/ppm |
- |
- |
19.4 and 27.9 |
-1.05 and 20.6 |
8.5 |
|
Pauling
electronegativity |
F
4.0 |
Cl
3.0 |
Br
2.8 |
I
2.5 |
H
2.1 |
With the increase in electronegativity of the halogen in the
molecule, the 1H
chemical shift for these molecules steadily decreases, but it
seems to be the opposite trend for the 13C chemical shifts?
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 |
Key words & phrases:
C2H5Br
CH3CH2Br Interpreting the proton H-1 NMR spectra of bromoethane, low resolution & high resolution proton
nmr spectra of bromoethane, H-1 nmr spectrum of bromoethane, understanding the
hydrogen-1 nmr spectrum of bromoethane, explaining the line splitting patterns from
spin-spin coupling in the
high resolution H-1 nmr spectra of bromoethane, revising the H-1 nmr spectrum of
bromoethane,
proton nmr of bromoethane, ppm chemical shifts of the H-1 nmr spectrum of
bromoethane,
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 bromoethane, how to work out the
number of chemically different protons in the structure of the bromoethane organic
molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR
spectrum of bromoethane using the n+1 rule to explain the spin - spin coupling ine
splitting in the proton nmr spectrum of bromoethane deducing the nature of the protons
from the chemical shifts ppm in the H-1 nmr spectrum of bromoethane
examining the 1H nmr spectrum of bromoethane analysing the 1-H nmr spectrum of
bromoethane how do you sketch and interpret the H-1 NMR spectrum of bromoethane
interpreting interpretation of the 1H proton spin-spin coupling causing line
splitting in the NMR spectrum of bromoethane
assignment of chemical shifts in the
proton 1H NMR spectrum of bromoethane formula explaining spin-spin coupling for line splitting
ethyl bromide
How do you interpret the H-1 NMR spectrum of
bromoethane How to interpret
the H-1 NMR spectrum of bromoethane Explanatory diagram of the chemical
shifts of the 1H H-1 proton NMR spectrum of the bromoethane
molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the
proton NMR spectrum of bromoethane. How to explain the H-1 NMR spectrum of
bromoethane. The chemical shifts and integrated values of the proton ratios in the 1-H NMR
spectrum of the bromoethane molecule. How to work out the molecular
structure of the bromoethane molecule from its proton NMR spectrum. The uses
and distinctive features of the proton NMR spectrum of the
bromoethane
molecule explained. What does the H-1 proton NMR spectrum chemical
shifts tell us about the
structure and properties of the bromoethane
molecule? explaining the spin-spin proton coupling effects in the 1H
NMR spectrum of bromoethane.
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 bromoethane
Links associated
with
bromoethane
The infrared spectrum of bromoethane
The mass spectrum of
chloroethane
The C-13 NMR spectrum of bromoethane
The chemistry of HALOGENOALKANES (haloalkanes)
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
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. |
