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The Carbon-13 NMR spectrum of
2-chlorobutane
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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 2-chlorobutane
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C-13
NMR spectroscopy - spectra index
See also
Comparing infrared, mass, 1H NMR & 13C NMR
spectra of the 4 structural isomers of C4H9Cl
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 - 2-chlorobutane here.
 ,
 ,
 ,
 ,
2-chlorobutane
For more see
Molecular structure, classification and
naming of
halogenoalkanes (haloalkanes)
Interpreting the C-13 NMR spectrum of 2-chlorobutane
As you can see from the diagram above there are
4 different chemical shift lines in the C-13 NMR spectrum of
2-chlorobutane
indicating 4 different chemical environments of the 4 carbon
atoms of 2-chlorobutane.
CH3CHClCH2CH3
(Note the 4 different colours indicating the
4 different chemical environments of the carbon atoms in
2-chlorobutane).
13C chemical shifts (a) to (d) on the C-13 NMR
spectrum diagram for 2-chlorobutane.
Note the decreasing effect on the 13C chemical shift as the
carbon atom is further from the more electronegative chlorine atom in 2-chlorobutane.
The carbon-13 NMR spectra provides direct evidence of
4 different carbon atom environments for the 4 carbon atoms in the
2-chlorobutane molecule,
deduced from the presence of 4 different 13C chemical
shifts (ppm).
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Comparing the infrared, mass, 1H NMR and 13C NMR
spectra of the 4 halogenoalkane isomers of C4H9Cl
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 1-chlorobutane,
2-chlorobutane, 1-chloro-2-methylpropane and 2-chloro-2-methylpropane
image sizes. These four molecules
are structural isomers of molecular formula C4H9Cl
and
exemplify the infrared, mass, 1H NMR and 13C NMR spectra of lower
aliphatic halogenoalkanes (haloalkanes, alkyl halides,
chloroalkanes, alkyl chlorides). |
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INFRARED SPECTRA
(above):
Apart from the significant differences in the fingerprint region at
wavenumbers 1500 to 400 cm-1, there are no other
great striking differences, but each could be identified from
its infrared spectrum. The infrared spectrum of
2-chloro-2-methylpropane is noticeably simpler in the
fingerprint region, perhaps due to
the greater symmetry of the molecule. |
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MASS SPECTRA (above):
Theoretically, all four can give the parent molecular ions of
m/z 92 and 94, but they are all relatively tiny peaks.
2-chlorobutane and 2-chloro-2-methylpropane give a base ion peak
of m/z 57. The base ion peak for 1-chlorobutane is m/z 56 and
that of 1-chloro-2-methylpropane is m/z 43. Each gives different
patterns of pairs of m/z values two mass units apart, in the
peak height ratio of 3:1, if the positive fragment contains a
chlorine atom (35Cl or 37Cl) e.g look for
m/z pairs 49/51, 63/65 and 77/79 in their mass spectra. |
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1H NMR SPECTRA
(above): The 1H NMR spectra of all four molecules give different
integrated proton ratios i.e.1-chlorobutane
four peaks of ratio 3:2:2:2; 2-chlorobutane four peaks of
ratio 3:3:2:1,
1-chloro-2-methylpropane three peaks of ratio 6:2:1 and
2-chloro-2-methylpropane gives just one peak '1' (effectively no ratio
involved), so all four molecular structures can be distinguished from each other by their
1H NMR spectra proton ratios, numbers of peaks and (n+1)
rule splitting patterns. |
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13C NMR SPECTRA
(above): The
13C NMR spectra of the four molecules show various numbers of
carbon-13 chemical environments i.e 1-chlorobutane and
2-chlorobutane show four 13C NMR resonances,
1-chloro-2-methylpropane three 13C NMR resonances and
2-chloro-2-methylpropane only two 13C resonances (3 and 2
chemical environments respectively. Therefore
1-chloro-2-methylpropane and 2-chloro-2-methylpropane can be
distinguished from the other three by their number of resonances
in their 13C NMR spectra, but 1-chlorobutane and 2-chlorobutane
cannot be distinguished from each other from their number of 13C
NMR resonance lines - other data would be required. |
Key words & phrases: C4H9Cl CH3CHClCH2CH3 Interpreting the C-13 NMR spectra of
2-chlorobutane, C-13 nmr spectrum of 2-chlorobutane, understanding the
carbon-13 nmr spectrum of 2-chlorobutane, explaining the line pattern in the high
resolution C-13 nmr spectra of 2-chlorobutane, revising the C-13 nmr spectrum of
2-chlorobutane, ppm
chemical shifts of the C-13 nmr spectrum of 2-chlorobutane, how to construct the diagram of
the C-13 nmr spectrum of 2-chlorobutane, how to analyse the chemical shifts in the
carbon-13 NMR spectrum of 2-chlorobutane deducing the chemical environment of all the
carbon atoms in 2-chlorobutane examining the c13 nmr spectrum of
2-chlorobutane analysing the
13-c nmr spectrum of 2-chlorobutane how do you sketch and interpret the C-13 NMR spectrum
of 2-chlorobutane interpreting interpretation of the C-13 NMR spectrum of
2-chlorobutane
assignment of chemical shifts in the 13C
NMR spectrum of 2-chlorobutane sec-butyl chloride
Molecular structure diagram of the
carbon-13 NMR diagram for the 13C NMR spectrum of 2-chlorobutane. Deducing the number
of different chemical environments of the carbon atoms in the 2-chlorobutane molecule
from the 13C chemical shifts in the carbon-13 NMR spectrum of 2-chlorobutane. Revision
notes on the carbon-13 NMR spectrum of 2-chlorobutane. Matching and deducing the
structure of the 2-chlorobutane molecule from its 13C NMR spectrum.
Carbon-13 NMR spectroscopy of aliphatic
halogenoalkanes haloalkanes alkyl halides alkyl chlorides chloroalkanes,
13C NMR spectra of 2-chlorobutane, an isomer of molecular formula
C4H9Cl explaining the carbon-13 13C
NMR spectrum of 2-chlorobutane
Links associated
with 2-chlorobutane
The chemistry of HALOGENOALKANES (haloalkanes)
revision notes INDEX
The
infrared spectrum of 2-chlorobutane (sec-butyl
chloride)
The mass
spectrum of 2-chlorobutane (sec-butyl
chloride)
The
H-1 NMR spectrum of 2-chlorobutane (sec-butyl
chloride)
C-13
NMR spectroscopy index
ALL SPECTROSCOPY INDEXES
All Advanced Organic
Chemistry Notes
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