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Interpreting the 13C NMR spectrum of
1-chlorobutane
[Author
©
Dr Phil Brown PhD:
Doc Brown's advanced level organic chemistry exam revision notes
suitable for students of UK A level chemistry courses & US K12 grade
11, grade 12 and AP honors chemistry courses: Molecular
spectroscopy - analysing the C-13 NMR spectrum of 1-chlorobutane
[updated
Mar 11th 2026 *]
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C-13 NMR
spectrum of CH3CH2CH2CH2Cl
LINKS associated
with 1-chlorobutane
The
chemistry of organic halogen compounds
This is a BIG
website, you need to take time to explore it
C-13
NMR spectroscopy - spectra index
See also
Comparing infrared, mass, 1H NMR & 13C NMR
spectra of the 4 structural isomers of C4H9Cl
Introductory note on the 13C NMR spectrum of 1-chlorobutane
Students and teachers please note that my explanation of the
carbon-13 NMR spectrum of 1-chlorobutane is designed for advanced, but
pre-university, chemistry courses.
The description does not involve
the chemical shift δ
spin-spin coupling effects for 1-chlorobutane and the relative size of the carbon-13
NMR shifts does not give the ratio of the carbon atoms in the
different non-equivalent chemical environments of the 1-chlorobutane molecule.
The most common solvent used for investigating the
13C
NMR
spectrum of compounds like 1-chlorobutane, is CDCl3 and other
deuterated solvents.
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 shifts, called chemical shifts, depend on the
individual (electronic) chemical environment of the 13C atoms in
an organic molecule - 1-chlorobutane here.
1-chlorobutane
C4H9Cl,
,
For more see
Molecular structure, classification and
naming of
halogenoalkanes (haloalkanes)
Interpreting the C-13 NMR spectrum of
1-chlorobutane
You can see from the
above there are four different C-13 NMR chemical shift lines
- which clearly show that the four carbon atoms of the
1-chlorobutane are in four in different chemical environments
(a) to (d) on the diagram
You can illustrate this with a coloured
structural formula of 1-chlorobutane.
CH3CH2CH2CH2Cl
Note the decreasing effect on the chemical shift as the
carbon atom is further from the more electronegative chlorine atom of
1-chlorobutane.
Summary of the C-13 NMR spectrum of 1-chlorobutane and extra comments
A structured breakdown of the ¹³C NMR spectrum of
1-chlorobutane (CH3–CH2–CH2–CH2–Cl),
with emphasis on chemical shifts, carbon environments,
misconceptions, and exam strategies.
Overview: Carbon
Environments in the C-13 NMR spectrum of 1-Chlorobutane
1-Chlorobutane contains four non-equivalent
carbon atoms, each in a distinct electronic
environment due to their position relative to the chlorine
atom and the alkyl chain.
Table: C-13
Chemical Shifts, Origins, and Environments for the C-13 NMR spectrum of
1-Chlorobutane
| Carbon |
Carbon Group |
Chemical
Shift (δ, ppm) |
Environment /
Origin |
| C1 |
–CH2–Cl |
~45–55, 44.7 ppm |
Deshielded by electronegative Cl |
| C2 |
–CH2–CH2–Cl |
~25–35, 34.8 ppm |
Slightly deshielded, mid-chain CH₂ |
| C3 |
–CH2–CH2–CH2Cl |
~20–25, 20.2 ppm |
Alkyl CH2, further from Cl |
| C4 |
–CH3 |
~10–15, 13.3 ppm |
Terminal methyl group, most shielded |
CH3CH2CH2CH2Cl
These values are approximate and may vary slightly
depending on solvent (typically CDCl3), concentration, and
instrument frequency.
Common
Misconceptions about the C-13 NMR spectrum of 1-Chlorobutane
(see also below)
- Assuming all CH2 groups are
equivalent: Each CH2 is in a different
electronic environment due to varying proximity to Cl or CH3.
- Expecting splitting patterns: Standard
¹³C spectra are proton-decoupled, so
signals appear as singlets — no multiplicity unless DEPT or
coupled spectra are used.
- Misinterpreting signal intensity:
Unlike ¹H NMR, peak height does not correlate with
number of carbons — integration is not typically
used in ¹³C NMR.
- Overlooking symmetry: Students may
incorrectly assume symmetry in linear chains — but
substitution (e.g. Cl) breaks equivalence.
Exam Tips
for questions involving the C-13 NMR spectrum of 1-Chlorobutane
(see above too)
- Count the number of signals first: Four
signals = four distinct carbon environments — helps
distinguish isomers.
- Identify the most downfield signal (~45–55 ppm):
This is the carbon directly bonded to Cl — a key diagnostic
feature.
- Use chemical shift ranges: Alkyl C
(0–50 ppm), C–Cl (20–60 ppm) — helps eliminate incorrect
structures.
- Compare with isomers: 2-chlorobutane
will show different shifts due to branching — useful in
structure deduction.
- Link to other spectra: Combine with IR
(C–Cl stretch) and MS (M⁺/M⁺+2 peaks) in synoptic questions.
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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: Interpreting the C-13 NMR spectra of
1-chlorobutane, C-13 nmr spectrum of 1-chlorobutane, understanding the
carbon-13 nmr spectrum of 1-chlorobutane, explaining the line pattern in the high
resolution C-13 nmr spectra of 1-chlorobutane, revising the C-13 nmr spectrum of
1-chlorobutane, ppm
chemical shifts of the C-13 nmr spectrum of 1-chlorobutane, how to construct the diagram of
the C-13 nmr spectrum of 1-chlorobutane, how to analyse the chemical shifts in
the carbon-13 NMR spectrum of 1-chlorobutane
Molecular structure diagram of the
carbon-13 NMR diagram for the 13C NMR spectrum of 1-chlorobutane. Deducing the number
of different chemical environments of the carbon atoms in the
1-chlorobutane molecule
from the 13C chemical shifts in the carbon-13 NMR spectrum of
1-chlorobutane. Revision
notes on the carbon-13 NMR spectrum of 1-chlorobutane. Matching and deducing the
structure of the 1-chlorobutane molecule from its 13C NMR spectrum.
Carbon-13 NMR spectroscopy of aliphatic
halogenoalkanes haloalkanes alkyl halides alkyl chlorides chloroalkanes,
13C NMR spectra of 1-chlorobutane, an isomer of molecular formula
C4H9Cl explaining the carbon-13 13C
decoupled NMR spectrum of 1-chlorobutane How do you interpret the chemical shifts of the C-13 NMR spectrum
of 1-chlorobutane How to interpret the C-13 NMR spectrum of
1-chlorobutane Explanatory diagram of the 13C C-13 carbon-13 NMR spectrum of the number of different carbon atom
environments in the 1-chlorobutane molecule from its carbon-13 NMR spectrum to
help work out the molecular structure of the 1-chlorobutane molecule? The uses
and distinctive features of the carbon-13 NMR spectrum of the
1-chlorobutane
molecule explained. What do the number and values of the chemical
shifts from the c-13 carbon-13 NMR spectrum tell us about the
1-chlorobutane
molecule? explaining the decoupled carbon-13 NMR spectrum of
1-chlorobutane with a detailed diagram of all the uncoupled C-13 chemical
shifts and intensities
Links associated with 1-chlorobutane
The chemistry of HALOGENOALKANES (haloalkanes)
revision notes INDEX
The infrared spectrum of 1-chlorobutane
(n-butyl chloride)
The mass spectrum of 1-chlorobutane
(n-butyl chloride)
The H-1 NMR spectrum of 1-chlorobutane
(n-butyl chloride)
C-13
NMR spectroscopy index
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