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Interpreting the
Carbon-13 NMR spectrum of methoxyethane
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Brown's Chemistry Advanced Level Pre-University Chemistry Revision Study
Notes for UK IB KS5 A/AS GCE advanced A level organic chemistry students US
K12 grade 11 grade 12 organic chemistry courses involving molecular
spectroscopy analysing C-13 NMR spectra of methoxyethane
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C-13
NMR spectroscopy - spectra index
See also
comparing the infrared, mass, 1H NMR and 13C NMR
spectra of the 3 isomers of C3H8O
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 - methoxyethane here.
Methoxyethane
Interpreting the C-13 NMR spectrum of methoxyethane
As you can see from the diagram above there are
3 different chemical shift lines in the C-13 NMR spectrum of
methoxyethane
indicating 3 different chemical environments of the 3 carbon
atoms of methoxyethane.
CH3OCH2CH3
(Note the 3 different colours indicating the
3 different chemical environments of the carbon atoms in
methoxyethane).
13C chemical shifts (a) to (c) on the C-13 NMR
spectrum diagram for methoxyethane.
Note the decreasing effect on the 13C
chemical shift as the carbon atom is further from the more
electronegative oxygen atom methoxyethane.
The carbon-13 NMR spectra provides direct evidence of
3 different carbon atom environments for the 3 carbon atoms in the
methoxyethane molecule,
deduced from the presence of 3 different 13C chemical
shifts (ppm).
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Comparing the infrared, mass, 1H NMR and 13C NMR
spectra of the 3 isomers of C3H8O
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 propan-1-ol,
propan-2-ol and methoxyethane image sizes. |
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I wasn't able to obtain an infrared
spectrum for methoxyethane, so I've added the infrared spectrum
of ethoxyethane to enable a few comparisons with two aliphatic
alcohols
Comparing the
infrared
spectra of
propan-1-ol,
propan-2-ol and
methoxyethane
Propan-1-ol,
propan-2-ol and methoxyethane
are structural isomers of molecular formula C3H8O
Propan-1-ol,
propan-2-ol and methoxyethane
exemplify infrared spectra of the lower members of the homologous series
of aliphatic alcohols and ethers |
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INFRARED SPECTRA
(above): There are, as expected, differences in the fingerprint region at
wavenumbers 1500 to 400 cm-1, but most absorptions
for all three molecules are the various C-O and the many C-H
vibrational modes. However, there is one characteristic distinguishing
absorption only present in the infrared spectra of alcohols, but
not in ethers, that is the broad O-H stretching vibration
peaking at ~3350 cm-1. There is also another broad
absorption band (origin?) peaking at ~650 cm-1 in the
alcohol spectra, but not in the ether spectra. |
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Comparing the
mass
spectra of
propan-1-ol,
propan-2-ol and
methoxyethane
Propan-1-ol,
propan-2-ol and methoxyethane
are structural isomers of molecular formula C3H8O
Propan-1-ol,
propan-2-ol and methoxyethane
exemplify the mass spectra of the lower members of the homologous series
of aliphatic alcohols and ethers |
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MASS SPECTRA (above):
The base ion peaks are m/z 45 for propan-2-ol and methoxyethane,
but that of propan-1-ol is m/z 31. Many of the fragmentation
ions are common to all three spectra. The m/z 45 ion is peak is
much smaller in the propan-1-ol spectrum compared to the other
two. |
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Comparing the
1H proton NMR
spectra of
propan-1-ol,
propan-2-ol and
methoxyethane
Propan-1-ol,
propan-2-ol and methoxyethane
are structural isomers of molecular formula C3H8O
Propan-1-ol,
propan-2-ol and methoxyethane exemplify the 1H proton NMR spectra of
the lower members of the homologous series of aliphatic alcohols and
ethers |
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1H NMR SPECTRA (above): The 1H NMR spectra of
all three molecules give different integrated proton ratios for the
different 1H chemical environments i.e. the proton
ratios are as follows: propan-1-ol
3:2:2:1; propan-2-ol 6:1:1 and methoxyethane
3:2:3. Therefore, all three can be distinguished by their
1H NMR spectra. |
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Comparing the
carbon-13 NMR
spectra of
propan-1-ol,
propan-2-ol and
methoxyethane
Propan-1-ol,
propan-2-ol and methoxyethane
are structural isomers of molecular formula C3H8O
Propan-1-ol,
propan-2-ol and methoxyethane exemplify the carbon-13 NMR spectra of
members of the lower members of the homologous series of aliphatic
alcohols and ethers |
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13C NMR SPECTRA
(above): The
13C NMR spectra of propan-1-ol and methoxyethane show
three different 13C NMR chemical shifts, but
propan-2-ol can be distinguished from the other two by
exhibiting only two chemical shift lines. You would need other
spectral data to distinguish propan-1-ol and methoxyethane. Two
of ethoxyethane's 13C resonances are shifted to higher values
due to the influence of the more electronegative oxygen atom
(only one large shift for the other two molecules). |
Key words & phrases:
C3H8O CH3OCH2CH3 Interpreting the C-13 NMR spectra of
methoxyethane, C-13 nmr spectrum of methoxyethane, understanding the
carbon-13 nmr spectrum of methoxyethane, explaining the line pattern in the high
resolution C-13 nmr spectra of methoxyethane, revising the C-13 nmr spectrum of
methoxyethane, ppm
chemical shifts of the C-13 nmr spectrum of methoxyethane, how to construct the diagram of
the C-13 nmr spectrum of methoxyethane, how to analyse the chemical shifts in the
carbon-13 NMR spectrum of methoxyethane deducing the chemical environment of all the
carbon atoms in methoxyethane examining the c13 nmr spectrum of
methoxyethane analysing the
13-c nmr spectrum of methoxyethane how do you sketch and interpret the C-13 NMR spectrum
of methoxyethane interpreting interpretation of the C-13 NMR spectrum of
methoxyethane
assignment of chemical shifts in the 13C
NMR for ethyl methyl ether
spectrum of methoxyethane methyl ethyl ether
CH3CH2OCH3
isomer of molecular formula C3H8O
Molecular structure diagram of the
carbon-13 NMR diagram for the 13C NMR spectrum of methoxyethane. Deducing the number
of different chemical environments of the carbon atoms in the methoxyethane molecule
from the 13C chemical shifts in the carbon-13 NMR spectrum of methoxyethane. Revision
notes on the carbon-13 NMR spectrum of methoxyethane. Matching and deducing the
structure of the methoxyethane molecule from its 13C NMR spectrum.
Carbon-13 NMR spectroscopy of aliphatic ethers,
13C NMR spectra of methoxyethane, an isomer of molecular formula C3H8O
Links associated
with methoxyethane
The
infrared spectrum of methoxyethane
The mass
spectrum of methoxyethane
The H-1
NMR spectrum of methoxyethane
C-13
NMR spectroscopy index
ALL SPECTROSCOPY INDEXES
All Advanced Organic
Chemistry Notes
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