|
Interpreting
and explaining the
Carbon-13 13C NMR spectrum of ethane
[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
spectrometry - analysing the 13C NMR spectra of ethane
[spectra
page updated
April 3rd 2026 *]
email doc brown
Re-edit 13C
NMR
spectrum of
CH3CH3
Links associated with ethane
* [privacy policy, cookies
and disclaimer]
This is a BIG chemistry website, PLEASE take time to explore it
C-13
NMR spectroscopy - spectra index
See also
comparing the infrared, mass, 1H NMR and 13C NMR spectra of ethane and
ethene
Introductory note on the 13C NMR spectrum of ethane
Students and teachers please note that my explanation of the
carbon-13 NMR spectrum of ethane is designed for advanced, but
pre-university, chemistry courses.
The description does not involve
the chemical shift δ
spin-spin coupling effects for ethane and the relative size of the carbon-13
NMR shifts does not give the ratio of the carbon atoms in the
different non-equivalent chemical environments of the ethane molecule.
The most common solvent used for investigating the
13C
NMR
spectrum of compounds like ethane, is CDCl3 and other
deuterated solvents.
TMS is the acronym for tetramethylsilane, formula Si(CH3)4,
whose 13C atoms are arbitrarily given a chemical shift of 0.0
ppm. This is the 'standard' in 13C NMR spectroscopy and all other
13C resonances, called chemical shifts, are measured with
respect to the TMS, and depend on the
individual (electronic) chemical environment of the 13C atoms in
an organic molecule - ethane here.
The alkane
ethane
 yes! just a dash!
The molecular structure and
naming of alkanes
Interpreting the C-13 NMR spectrum of ethane
As you can see from the diagram is only one chemical shift line in the C-13 NMR spectrum of
ethane
indicating both carbon
atoms of ethane are in the same chemical environment.
CH3CH3
13C chemical shifts (a) 8.5 ppm on the C-13 NMR
spectrum diagram for ethane.
The carbon-13 NMR spectra provides direct evidence of
just one carbon atom environments for the 2 carbon atoms in the
ethane molecule,
deduced from the presence of only one 13C NMR chemical
shifts (ppm).
The appearance of
just one 13C peak in the C-13 NMR spectrum of
ethane, tells you unambiguously, that both carbon atoms are
equivalent to each other -
both C's in the same chemical environment.
Note that the even simpler molecule of
methane CH4, will also only give one peak on a C-13
NMR spectrum.
|
Comparing the infrared, mass, 1H NMR and 13C NMR
spectra of
ethane and ethene
NOTE: The images are linked to their
original detailed spectral analysis pages AND can be doubled in
size with touch screens to
increase the definition to the original ethane and
ethene image sizes. |
 |
 |
|
INFRARED SPECTRA:
Apart from the significant differences in the fingerprint region at
wavenumbers 1500 to 400 cm-1, the most striking
differences are (i) the band at ~1900 cm-1 for ethene,
absent in the ethane spectrum, (ii) the bands at 800 cm-1
for ethane (CH3 vibrations), absent or much weaker in
ethene, and (iii) the strong absorptions at ~1000 cm-1
for ethene, completely absent in the ethane spectrum. |
 |
 |
|
MASS SPECTRA: Both
ethane and ethene show some similarities in their mass
spectra e.g. m/z ions 25 to 28 for [C2Hx]+
(x = 1 to 4) ions and in both cases the base ion peak has an m/z
of 28. However, the molecular ion peaks will be different
because of their different relative molecular masses i.e. ethane
m/z 30 and ethene m/z 28. Ethane also has a prominent m/z ion
peak of 29, which is tiny in the ethene mass spectrum (and only
due to 1% 13C atoms in the parent molecular ion). |
 |
 |
|
1H NMR SPECTRA: The 1H NMR spectra of
ethane and ethene are similar in that that both give one single
singlet resonance line in their proton NMR spectra. All the
protons in each molecule are equivalent to each other and occupy
the same chemical environment due to the symmetry of the
molecule, so no resonance splitting. However the two 1H
chemical shifts are significantly different due the different
shielding effects of the -CH3 and =CH2
groupings respectively. |
|
|
 |
|
13C NMR SPECTRA: The
1C NMR spectra of ethane and ethene are similar in that that
both give one single resonance line in their carbon-13 NMR
spectra. In both molecules the two carbon atoms occupy the same
chemical environment due to the symmetry of the molecule.
However the two 13C chemical shifts are significantly
different due the different shielding effects of the -CH3
and =CH2
groupings respectively. The 13C chemical shift for
ethane is much lower. |
Key words & phrases:
C2H6 CH3CH3 Interpreting the C-13 NMR spectra of
ethane, C-13 nmr spectrum of ethane, understanding the
carbon-13 nmr spectrum of ethane, explaining the line pattern in the high
resolution C-13 nmr spectra of ethane, revising the C-13 nmr spectrum of ethane, ppm
chemical shifts of the C-13 nmr spectrum of ethane, how to construct the diagram of
the C-13 nmr spectrum of ethane, how to analyse the chemical shifts in the
carbon-13 NMR spectrum of ethane deducing the chemical environment of all the
carbon atoms in ethane examining the c13 nmr spectrum of ethane analysing the
13-c nmr spectrum of ethane how do you sketch and interpret the C-13 NMR spectrum
of ethane interpreting interpretation of the C-13 NMR spectrum of ethane
assignment of chemical shifts in the 13C
NMR spectrum of ethane type functional group alkane How do you interpret the chemical shifts of the C-13 NMR spectrum
of ethane How to interpret the C-13 NMR spectrum of ethane Explanatory diagram of the 13C C-13 carbon-13 NMR spectrum of the number of different carbon atom
environments in the ethane molecule from its carbon-13 NMR spectrum to
help work out the molecular structure of the ethane molecule? The uses
and distinctive features of the carbon-13 NMR spectrum of the ethane
molecule explained. What do the number and values of the chemical
shifts from the c-13 carbon-13 NMR spectrum tell us about the ethane
molecule? explaining the decoupled carbon-13 NMR spectrum of ethane
with a detailed interpretation diagram of all the C-13 chemical shifts and
intensities
Links associated
with
ethane
The chemistry of ALKANES
revision notes INDEX
The
infrared spectrum of ethane
The
mass spectrum of ethane
The H-1 NMR spectrum of
ethane
C-13
NMR spectroscopy index
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 (13C NMR spectra of ethane) 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. |
