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The H-1
hydrogen-1 (proton) NMR spectrum of cyclopropane
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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 cyclopropane
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H-1 proton NMR spectroscopy -
spectra index
See also
comparing the infrared, mass, 1H
NMR and 13C NMR
spectra of propane, cyclopropane and propene
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 shifts, called chemical shifts, depend on the
individual (electronic) chemical environment of the hydrogen atoms
in an organic molecule - cyclopropane here.
The chemical shifts quoted in ppm on the diagram of
the H-1 NMR spectrum of cyclopropane 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 cyclopropane molecule.
Cyclopropane C3H6,
 ,
Interpreting the
H-1 NMR spectrum of
cyclopropane
All eight hydrogen atoms are equivalent as
cyclopropane is a highly symmetrical molecule, the three carbon
atoms are in the same plane with the protons distributed
symmetrically above and below the plane of the triangle of
carbon atoms.
Therefore only one
1H
Chemical shift of 0.20 ppm is observed and with no splitting - there are no
neighbouring non-equivalent protons.
The presence of one unsplit proton NMR
resonance shows that all 6 protons occupy the same
chemical environment.
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Number of protons 1H
causing splitting |
Splitting pattern produced from the
n+1 rule 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 |
|
1 |
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5 |
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10 |
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10 |
|
5 |
|
1 |
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| 6
creates a septet |
1 |
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6 |
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15 |
|
20 |
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15 |
|
6 |
|
1 |
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Comparing the infrared, mass, 1H NMR and 13C NMR
spectra of propane, cyclopropane and propene
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. |
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Comparing the
infrared
spectra of propane, propene and cyclopropane.
Cyclopropane and propene are structural isomers of molecular formula C3H6.
Propane
and propene exemplify the infrared spectra of lower members of the alkane
and alkene homologous series of CnH2n+2 and CnH2n
hydrocarbon
molecules where n = 3. |
|
INFRARED SPECTRA
(above):
Apart from the significant differences in the fingerprint region at
wavenumbers 1500 to 400 cm-1, the most striking
differences are: (i) propene shows the characteristic absorption
at ~1700 cm-1 for the C=C stretching vibrations,
absent in the other two spectra, (ii) cyclopropane shows an absorption band
at 2200 cm-1, absent in the other two spectra, (iii)
propane has an absorption band at ~750 cm-1, absent
in the other two spectra. |
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Comparing the
mass
spectra of propane, propene and cyclopropane.
Cyclopropane and propene are structural isomers of molecular formula C3H6.
Propane
and propene exemplify the mass spectra of lower members of the alkane
and alkene homologous series of CnH2n+2 and CnH2n
hydrocarbon
molecules where n = 3. |
|
MASS SPECTRA (above):
All three hydrocarbons show some similarities in their mass
spectra e.g. m/z ions 26 to 28 for [C2Hx]+
(x = 2 to 4) and m/z 14 and 15 ions - but these are found in
most aliphatic hydrocarbon spectra. The molecular ion peaks will
be the same for the isomeric propene and cyclopropane (m/z 42)
but that of propane will be 2 mass units higher at m/z 44. The
base ion peak m/z values are all different, propane 29, propene
41 and cyclopropane 42. |
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Comparing the
1H proton NMR
spectra of propane, propene and cyclopropane.
Cyclopropane and propene are structural isomers of molecular formula C3H6.
Propane
and propene exemplify the 1H proton NMR spectra of lower members of the alkane
and alkene homologous series of CnH2n+2 and CnH2n
hydrocarbon
molecules where n = 3. |
|
1H NMR SPECTRA (above): The 1H NMR spectra of
all three molecules give different proton ratios i.e. propane
3:1 (actually 6:2 in the molecule), propene 2:1:3 (spectrum and
molecule) and cyclopropane just a singlet for the six protons,
so all three can be distinguished from each other by their
1H NMR spectra.. |
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Comparing the
carbon-13 NMR
spectra of propane, propene and cyclopropane.
Cyclopropane and propene are structural isomers of molecular formula C3H6.
Propane
and propene exemplify the carbon-13 NMR spectra of lower members of the alkane
and alkene homologous series of CnH2n+2 and CnH2n
hydrocarbon
molecules where n = 3. |
|
13C NMR SPECTRA
(above): The
13C NMR spectra of the three molecules show different numbers of
carbon-13 chemical environments i.e propane 2, propene 3 and cyclopropane
only 1, so all three could be distinguished from each other. |
Key words & phrases: Interpreting the proton H-1 NMR spectra of
cyclopropane, low resolution & high resolution proton
nmr spectra of cyclopropane, H-1 nmr spectrum of cyclopropane, understanding the
hydrogen-1 nmr spectrum of cyclopropane, explaining the line splitting patterns in the
high resolution H-1 nmr spectra of cyclopropane, revising the H-1 nmr spectrum of
cyclopropane,
proton nmr of cyclopropane, ppm chemical shifts of the H-1 nmr spectrum of
cyclopropane,
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 cyclopropane, how to work out the
number of chemically different protons in the structure of the cyclopropane organic
molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR
spectrum of cyclopropane using the n+1 rule to explain the spin - spin coupling ine
splitting in the proton nmr spectrum of cyclopropane deducing the nature of the protons
from the chemical shifts ppm in the H-1 nmr spectrum of cyclopropane
examining the 1H nmr spectrum of cyclopropane analysing the 1-H nmr spectrum of
cyclopropane how do you sketch and interpret the H-1 NMR spectrum of
cyclopropane interpreting interpretation of the H-1
proton NMR spectrum of cyclopropane
Molecular structure diagram of the
proton NMR diagram for the 1H NMR spectrum of cyclopropane. The proton ratio in the
1H NMR spectrum of cyclopropane. Deducing the number of different chemical
environments of the protons in the cyclopropane molecule from the 1H chemical shifts
in the hydrogen-1 NMR spectrum of cyclopropane. Analysing the high resolution 1H NMR
spectrum of cyclopropane. Analysing the low resolution 1H NMR spectrum of
cyclopropane. You
may need to know the relative molecular mass of cyclopropane to deduce the molecular
formula from the proton ratio of the 1H NMR spectrum of cyclopropane. Revision notes
on the proton NMR spectrum of cyclopropane. Matching and deducing the structure of
the cyclopropane molecule from its hydrogen-1 NMR spectrum.
Links associated
with cyclopropane
The chemistry of ALKANES
revision notes INDEX
The
infrared spectrum of cyclopropane
The mass
spectrum of cyclopropane
The
C-13 NMR spectrum of cyclopropane
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
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