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Interpreting the
H-1 hydrogen-1 (proton) 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 H-1 NMR spectra of methoxyethane
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H-1 proton 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 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 - methoxyethane here.
The chemical shifts quoted in ppm on the diagram of
the H-1 NMR spectrum of methoxyethane 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 methoxyethane molecule.
Methoxyethane
Interpreting the
H-1 NMR spectrum of
methoxyethane
In terms of spin-spin coupling from the possible proton magnetic orientations,
for methoxyethane I
have only considered the interactions of
non-equivalent protons on adjacent carbon atoms
e.g. -CH2-CH3
protons here.
For relatively simple molecules, the low
resolution H-1 NMR spectrum of methoxyethane is a good starting point
(low resolution diagram above) from which you can deduce ....
,,, the hydrogen atoms (protons) of methoxyethane occupy
3
different chemical environments so that the low resolution NMR
spectra should show 3 principal peaks of different H-1 NMR chemical shifts (diagram above for
methoxyethane).
CH3OCH2CH3
Note the proton ratio 3:2:3 of the three colours of the protons
in the three chemically different environments. Chemical shifts
(b), (a) and (c) on the H-1 NMR
spectrum diagram for methoxyethane.
Although there are 8 hydrogen atoms in the molecule,
there are only 3 possible different chemical
environments for the hydrogen atoms in methoxyethane molecule.
The integrated signal proton ratio 3:2:3 observed
in the high resolution H-1 NMR spectrum, corresponds with
the structural formula of methoxyethane.
The high resolution 1H NMR
spectrum of methoxyethane
All low and high resolution spectra of
methoxyethane
show 3 groups of proton resonances and in the 3:2:3 ratio expected from the
formula of methoxyethane.
The ppm quoted on the diagram represent the peak
of resonance intensity for a particular proton group in the
molecule of methoxyethane - 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 methoxyethane below.
So, using the chemical shifts and applying the
n+1 rule to
methoxyethane
and make some predictions using some colour coding! (In problem
solving you work the other way round!)
(a) 1H
Chemical shift of methyl protons 3.25 ppm: CH3OCH2CH3
This proton resonance is not split by
other protons - non are on an adjacent carbon atoms, so
just a singlet is observed,
Evidence for the presence of an alkyl group
not connected to another atom with protons bonded to it
in the molecule of methoxyethane
(b) 1H
Chemical shift of CH2 protons 3.52 ppm: CH3OCH2CH3
This proton resonance is split into a
1:3:3:1 quartet by the adjacent methyl protons (n+1 =
4).
Evidence for the presence of a methyl group
in the molecule of methoxyethane
(c) 1H
Chemical shift of methyl protons 1.42 ppm: CH3OCH2CH3
This proton resonance is split into a
1:2:1 triplet by the adjacent CH2 protons
(n+1 = 3).
Evidence for the presence of a CH2 group
in the molecule of methoxyethane
Note the decreasing effect on the 1H chemical shift as the
proton is further from the more electronegative oxygen atom in methoxyethane.
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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. Methoxyethane shows typical triplet
and quartet splitting patterns of an 'isolated' ethyl group with
no other C-H adjacent protons.. |
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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. |
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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 |
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1 |
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| 1
creates a doublet |
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1 |
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1 |
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| 2
creates a triplet |
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1 |
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2 |
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1 |
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| 3
creates a quartet |
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1 |
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3 |
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3 |
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1 |
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| 4
creates a quintet |
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1 |
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4 |
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6 |
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4 |
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1 |
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| 5
creates a sextet |
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1 |
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5 |
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10 |
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10 |
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5 |
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1 |
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| 6
creates a septet |
1 |
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6 |
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15 |
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20 |
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15 |
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6 |
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1 |
Key words & phrases:
C3H8O
CH3OCH2CH3 Interpreting the proton H-1 NMR spectra of methoxyethane, low resolution & high resolution proton
nmr spectra of methoxyethane, H-1 nmr spectrum of methoxyethane, understanding the
hydrogen-1 nmr spectrum of methoxyethane, explaining the line splitting patterns from
spin-spin coupling in the
high resolution H-1 nmr spectra of methoxyethane, revising the H-1 nmr spectrum of
methoxyethane,
proton nmr of methoxyethane, ppm chemical shifts of the H-1 nmr spectrum of
methoxyethane,
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 methoxyethane, how to work out the
number of chemically different protons in the structure of the methoxyethane organic
molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR
spectrum of methoxyethane using the n+1 rule to explain the spin - spin coupling ine
splitting in the proton nmr spectrum of methoxyethane deducing the nature of the protons
from the chemical shifts ppm in the H-1 nmr spectrum of methoxyethane
examining the 1H nmr spectrum of methoxyethane analysing the 1-H nmr spectrum of
methoxyethane how do you sketch and interpret the H-1 NMR spectrum of
methoxyethane
interpreting interpretation of the 1H proton spin-spin coupling causing line
splitting in the NMR spectrum of methoxyethane
assignment of chemical shifts in the
proton 1H NMR spectrum of methoxyethane formula explaining spin-spin coupling for line splitting
for ethyl methyl ether
spectrum of methoxyethane methyl ethyl ether
CH3CH2OCH3 isomer of molecular
formula C3H8O Molecular structure diagram of the
proton NMR diagram for the 1H NMR spectrum of methoxyethane. The proton ratio in the
1H NMR spectrum of methoxyethane. Deducing the number of different chemical
environments of the protons in the methoxyethane molecule from the 1H chemical shifts
in the hydrogen-1 NMR spectrum of methoxyethane. Analysing the high resolution 1H NMR
spectrum of methoxyethane. Analysing the low resolution 1H NMR spectrum of
methoxyethane. You
may need to know the relative molecular mass of methoxyethane to deduce the molecular
formula from the proton ratio of the 1H NMR spectrum of methoxyethane. Revision notes
on the proton NMR spectrum of methoxyethane. Matching and deducing the structure of
the methoxyethane molecule from its hydrogen-1 NMR spectrum.
Proton NMR spectroscopy of aliphatic ethers,
1H NMR spectra of methoxyethane, an isomer of molecular formula C3H8O
Links associated
with methoxyethane
H-1 proton NMR spectroscopy index
(Please
read 8 points at the top of the 1H NMR index page)
The
infrared spectrum of methoxyethane
The mass
spectrum of methoxyethane
The
C-13 NMR spectrum of methoxyethane
ALL SPECTROSCOPY INDEXES
All Advanced Organic
Chemistry Notes
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