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The H-1
hydrogen-1 (proton) NMR spectrum of 2,2,3-trimethylbutane
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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 2,2,3-trimethylbutane
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H-1 proton NMR spectroscopy -
spectra index
See also
comparing the
1H NMR and 13C NMR spectra of the nine alkane structural isomers of C7H16
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 - 2,2,3-trimethylbutane here.
The chemical shifts quoted in ppm on the diagram of
the H-1 NMR spectrum of 2,2,3-trimethylbutane 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 2,2,3-trimethylbutane molecule.
2,2,3-trimethylbutane C7H16
For more
see
The molecular structure,
classification and
naming of alkanes
Interpreting the
H-1 NMR spectrum of
2,2,3-trimethylbutane
For relatively simple molecules, the low
resolution H-1 NMR spectrum of 2,2,3-trimethylbutane is a good starting point
(low resolution diagram above).
Theoretically, the hydrogen atoms (protons) of
2,2,3-trimethylbutane should occupy 3 different chemical
environments so that the high resolution NMR
spectra should show 3 principal peaks of different H-1 NMR chemical shifts (diagram above for
2,2,3-trimethylbutane).
The low resolution spectrum only shows two
peaks in the proton ration 15:1
(CH3)3CCH(CH3)2
Note the proton ratio 9:1:6 of the 3 colours of the protons
in the 3 chemically different environments
Chemical shifts (a) to (c) on the H-1 NMR
spectrum diagram for 2,2,3-trimethylbutane.
Although there are 16 hydrogen atoms in the molecule,
there are only 3 possible different chemical environments for the
hydrogen atoms in 2,2,3-trimethylbutane
The integrated signal proton ratio 9:1:6 observed
in the very high resolution H-1 NMR spectrum, corresponds with
the structural formula of 2,2,3-trimethylbutane.
The high resolution 1H NMR
spectrum of 2,2,3-trimethylbutane
The ppm quoted on the diagram represent the peak
of resonance intensity for a particular proton group in the
molecule of 2,2,3-trimethylbutane - 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 2,2,3-trimethylbutane below.
So, using the chemical shifts and applying the
n+1 rule to
2,2,3-trimethylbutane
and make some predictions using some colour coding! (In problem
solving you work the other way round!)
(a) 1H
Chemical shift 0.834 ppm, 3 x methyl protons: (CH3)3CCH(CH3)2
This proton resonance is not split
because there are no protons on the adjacent carbon
atom, so this produces a singlet resonance.
(b) 1H
Chemical shift 0.830 ppm, 2 x methyl protons: (CH3)3CCH(CH3)2
This resonance is split into a doublet
by the CH proton (n+1 = 2)
Evidence for the presence of a CH group
in the molecule of 2,2,3-trimethylbutane
You need very high resolution to sort
out 1H NMR resonances (a) and (b).
(c) 1H
Chemical shift 1.38 ppm, CH proton : (CH3)3CCH(CH3)2
This resonance is split into a septet by
the 2 x CH3 protons (n+1 = 7)
Evidence for the presence of a CH3-C-CH3 grouping
in the molecule of 2,2,3-trimethylbutane
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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 |
|
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 |
|
1 |
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| 5
creates a sextet |
|
1 |
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5 |
|
10 |
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10 |
|
5 |
|
1 |
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| 6
creates a septet |
1 |
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6 |
|
15 |
|
20 |
|
15 |
|
6 |
|
1 |
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Comparing the
1H NMR and 13C NMR spectra of the nine alkane structural isomers of C7H16
You can distinguish all 9 isomers from a data combination of their number of
1H NMR
chemical shifts,
and their resulting integrated 1H proton ratios, plus, their number of
13C
chemical shifts. |
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Name of the alkane structural isomer of molecular
formula C7H16 |
Abbreviated structural formulae
of the nine isomers of molecular formula C7H16 (interpretation complications with 3-methylhexane and
2,3-dimethylpentane because they exhibit R/S isomerism due to a
chiral carbon) |
Skeletal formula of the
nine
alkane isomers of
molecular formula C7H16 |
Number of 1H NMR chemical shifts (δ) and
proton ratio (links
to spectrum) |
Number of 13C chemical shifts (δ)
(links
to spectrum) |
| heptane |
 |
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4 δ: proton ratio: 3:2:2:1 (6:4:4:2 in the molecule) |
4 δ shifts |
| 2-methylhexane |
 |
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6 δ: proton ratio :
6:3:2:2:2:1 |
6 δ shifts |
| 3-methylhexane |
 |
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7 δ: proton ratio:
3:3:3:2:2:2:1 (simplification) !!! |
7
δ shifts |
| 3-ethylpentane |
 |
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3 δ: proton ratio:
9:6:1 |
3 δ
shifts |
| 2,2-dimethylpentane |
 |
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4 δ: proton ratio:
9:3:2:2 |
5 δ shifts |
|
2,3-dimethylpentane |
 |
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6 δ: proton ratio:
6:3:3:2:1:1 (simplification) !!! |
6 δ
shifts (simplification) !!! |
|
2,4-dimethylpentane |
 |
 |
3 δ: proton ratio:
12:2:2 |
3 δ
shifts |
| 3,3-dimethylpentane |
 |
 |
3 δ: proton ratio:
3:3:2 (6:4:4 in the molecule) |
4 δ
shifts |
| 2,2,3-trimethylbutane |
|
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3 δ: proton ratio:
9:6:1 |
4 δ shifts |
Key words & phrases:
C7H16
Interpreting the proton H-1 NMR spectra of
2,2,3-trimethylbutane, low resolution & high resolution proton
nmr spectra of 2,2,3-trimethylbutane, H-1 nmr spectrum of 2,2,3-trimethylbutane, understanding the
hydrogen-1 nmr spectrum of 2,2,3-trimethylbutane, explaining the line splitting patterns in the
high resolution H-1 nmr spectra of 2,2,3-trimethylbutane, revising the H-1 nmr spectrum of
2,2,3-trimethylbutane,
proton nmr of 2,2,3-trimethylbutane, ppm chemical shifts of the H-1 nmr spectrum of
2,2,3-trimethylbutane,
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 2,2,3-trimethylbutane, how to work out the
number of chemically different protons in the structure of the
2,2,3-trimethylbutane organic
molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR
spectrum of 2,2,3-trimethylbutane using the n+1 rule to explain the spin - spin coupling ine
splitting in the proton nmr spectrum of 2,2,3-trimethylbutane deducing the nature of the protons
from the chemical shifts ppm in the H-1 nmr spectrum of 2,2,3-trimethylbutane
examining the 1H nmr spectrum of 2,2,3-trimethylbutane analysing the 1-H nmr spectrum of
2,2,3-trimethylbutane how do you sketch and interpret the H-1 NMR spectrum of
2,2,3-trimethylbutane
interpreting interpretation of the 1H proton NMR spectrum of
2,2,3-trimethylbutane
(CH3)3CCH(CH3)2
(H3C)3CCH(CH3)2 Molecular structure diagram of the
proton NMR diagram for the 1H NMR spectrum of 2,2,3-trimethylbutane. The proton ratio in the
1H NMR spectrum of 2,2,3-trimethylbutane. Deducing the number of different chemical
environments of the protons in the 2,2,3-trimethylbutane molecule from the 1H chemical shifts
in the hydrogen-1 NMR spectrum of 2,2,3-trimethylbutane. Analysing the high resolution 1H NMR
spectrum of 2,2,3-trimethylbutane. Analysing the low resolution 1H NMR spectrum of
2,2,3-trimethylbutane. You
may need to know the relative molecular mass of 2,2,3-trimethylbutane to deduce the molecular
formula from the proton ratio of the 1H NMR spectrum of
2,2,3-trimethylbutane. Revision notes
on the proton NMR spectrum of 2,2,3-trimethylbutane. Matching and deducing the structure of
the 2,2,3-trimethylbutane molecule from its hydrogen-1 NMR spectrum.
Proton NMR spectroscopy of aliphatic alkanes,
1H NMR spectra of 2,2,3-trimethylbutane, a structural isomer of molecular formula
C7H16
Links associated
with 2,2,3-trimethylbutane
The chemistry of ALKANES
revision notes INDEX
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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Infrared spectra of the isomers of C7H16
The infrared
spectrum of heptane
The
infrared spectrum of 2-methylhexane
The
infrared spectrum of 3-methylhexane
The
infrared spectrum of 3-ethylpentane
The infrared spectrum of
2,2-dimethylpentane
The infrared spectrum of
2,3-dimethylpentane
The infrared spectrum of
2,4-dimethylpentane
The infrared spectrum of
3,3-dimethylpentane
The infrared spectrum
of 2,2,3-trimethylbutane
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Mass spectra of the isomers of C7H16
The mass
spectrum of heptane
The mass
spectrum of 2-methylhexane
The mass
spectrum of 3-methylhexane
The
mass spectrum of 3-ethylpentane
The mass spectrum of
2,2-dimethylpentane
The mass spectrum of
2,3-dimethylpentane
The mass spectrum of
2,4-dimethylpentane
The mass spectrum of
3,3-dimethylpentane
The mass
spectrum of 2,2,3-trimethylbutane
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H-1 proton NMR spectra of ALKANES
1H NMR spectra of the isomers of C7H16
The H-1 NMR
spectrum of heptane
The
H-1 NMR spectrum of 2-methylhexane
The
H-1 NMR spectrum of 3-methylhexane
The
H-1 NMR spectrum of 3-ethylpentane
The H-1 NMR spectrum of
2,2-dimethylpentane
The H-1 NMR spectrum of
2,3-dimethylpentane
The H-1 NMR spectrum of
2,4-dimethylpentane
The H-1 NMR spectrum of
3,3-dimethylpentane
The H-1
NMR spectrum of 2,2,3-trimethylbutane
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C-13 carbon-13 NMR spectra
of ALKANES
13C NMR spectra of the isomers of C7H16
The C-13 NMR
spectrum of heptane
The
C-13 NMR spectrum of 2-methylhexane
The
C-13 NMR spectrum of 3-methylhexane
The
C-13 NMR spectrum of 3-ethylpentane
The C-13 NMR spectrum of
2,2-dimethylpentane
The C-13 NMR spectrum of
2,3-dimethylpentane
The C-13 NMR spectrum of
2,4-dimethylpentane
The C-13 NMR spectrum of
3,3-dimethylpentane
The
C-13 NMR spectrum of 2,2,3-trimethylbutane
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