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Interpreting the
13C NMR spectrum of
2-chloropropane
[Author
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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 2-chloropropane
[updated
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analysis C-13 NMR spectrum of
CH3CHClCH3
Links associated
with 2-chloropropane
The
chemistry of organic halogen compounds
This is a BIG
chemistry website, please take time to explore it
C-13
NMR spectroscopy - spectra index
Introductory note on the 13C NMR spectrum of 2-chloropropane
Students and teachers please note that my explanation of the
carbon-13 NMR spectrum of 2-chloropropane is designed for advanced, but
pre-university, chemistry courses.
The description does not involve
the chemical shift δ
spin-spin coupling effects for 2-chloropropane 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
2-chloropropane molecule.
The most common solvent used for investigating the
13C
NMR
spectrum of compounds like 2-chloropropane, 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 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-chloropropane here.
2-chloropropane C3H7Cl
The molecular structure and naming of haloalkanes
Interpreting the C-13 NMR spectrum of 2-chloropropane
As you can see from the diagram above there are
2 different chemical shift lines in the C-13 NMR spectrum of
2-chloropropane
indicating 2 different chemical environments of the 3 carbon
atoms of 2-chloropropane.
CH3CHClCH3
(Note the 2 different colours indicating the
2 different chemical environments of the 3 carbon atoms in
2-chloropropane).
13C chemical shifts
(a) to (b) on the C-13 NMR
spectrum diagram for 2-chloropropane.
The carbon atoms of the
two methyl groups of 2-chloropropane are equivalent to each other.
Note the decreased effect on the 13C chemical shift as the
carbon atom is further from the more electronegative chlorine atom of 2-chloropropane.
The carbon-13 NMR spectra provides direct evidence of
2 different carbon atom environments for the 3 carbon atoms in the
2-chloropropane molecule,
deduced from the presence of 2 different 13C chemical
shifts (ppm).
Summary of key points for the C-13 NMR spectrum of 2-chloropropane plus
extra exam revision comments
The ¹³C NMR spectrum of 2-chloropropane (CH3CHClCH3)
with clarity, structure, and exam-board precision. This molecule is
symmetrical and contains three carbon atoms, but
only two distinct carbon environments, making it a
great example for reinforcing chemical shift logic and
symmetry-based reasoning.
Key Features of
the
C-13 NMR spectrum of 2-chloropropane
- Two signals expected due to symmetry: both CH3
groups are equivalent.
- Electronegative chlorine deshields the adjacent
carbon, shifting its signal downfield.
- No splitting in standard ¹³C spectra (unless
DEPT or coupled spectra are used).
- Peak intensity is not proportional to the
number of carbons — integration is not used.
C-13 Chemical
Shifts and Their Origins for
the
C-13 NMR spectrum of 2-chloropropane
| Chemical Shift (δ, ppm) |
Carbon Type |
Environment |
Notes |
| ~45, 53.8 ppm |
CH (methine) |
Adjacent to Cl |
Deshielded due to electronegative Cl |
| ~20, 27.3 ppm |
CH3 (methyl ×2) |
Equivalent methyl groups |
Shielded, distant from Cl |
CH3CHClCH3
These values may vary slightly depending on solvent and
concentration, but are typical for halogenoalkanes.
Common Misconceptions
about
the
C-13 NMR spectrum of 2-chloropropane
- Expecting three peaks: Students often forget
that symmetrical CH3 groups give a single signal.
- Assuming peak height = number of carbons:
Unlike ¹H NMR, peak intensity in ¹³C NMR is not quantitative.
- Misidentifying the CH carbon: It appears
downfield (~45 ppm) due to Cl, not because it’s a quaternary carbon.
- Overinterpreting absence of peaks: Some carbons
may be weakly absorbing or broadened, especially quaternary ones.
Exam Revision Tips
for questions involving
the
C-13 NMR spectrum of 2-chloropropane (AQA, Edexcel, OCR,
WJEC, CCEA, CIE, IB)
- Count environments first: Use symmetry to
predict number of signals.
- Use chemical shift tables: Most boards provide
reference ranges — match peaks to environments.
- Don’t rely on peak height: Focus on position
(δ) and number of signals.
- Compare similar compounds: E.g. 2-chloropropane
versus propan-2-ol — useful for distinguishing halogenoalkanes from
alcohols.
- Practice with unknowns: Some boards (OCR, IB,
Edexcel) expect interpretation from raw spectra.
- Know typical ranges:
- CH adjacent to Cl: ~40–50 ppm
- CH3 groups: ~10–25 ppm
Key words & phrases:
C3H7Cl CH3CHClCH3 Interpreting the C-13 NMR spectra of
2-chloropropane, C-13 nmr spectrum of 2-chloropropane, understanding the
carbon-13 nmr spectrum of 2-chloropropane, explaining the line pattern in the high
resolution C-13 nmr spectra of 2-chloropropane, revising the C-13 nmr spectrum of
2-chloropropane, ppm
chemical shifts of the C-13 nmr spectrum of 2-chloropropane, how to construct the diagram of
the C-13 nmr spectrum of 2-chloropropane, how to analyse the chemical shifts in the
carbon-13 NMR spectrum of 2-chloropropane deducing the chemical environment of all the
carbon atoms in 2-chloropropane examining the c13 nmr spectrum of
2-chloropropane analysing the
13-c nmr spectrum of 2-chloropropane how do you sketch and interpret the C-13 NMR spectrum
of 2-chloropropane interpreting interpretation of the C-13 NMR spectrum of
2-chloropropane
assignment of chemical shifts in the 13C
NMR spectrum of
isopropyl chloride
How do you interpret the chemical shifts of the C-13 NMR spectrum
of 2-chloropropane How to interpret the C-13 NMR spectrum of
2-chloropropane Explanatory diagram of the 13C C-13 carbon-13 NMR spectrum of the number of different carbon atom
environments in the 2-chloropropane molecule from its carbon-13 NMR spectrum to
help work out the molecular structure of the 2-chloropropane molecule? The uses
and distinctive features of the carbon-13 NMR spectrum of the
2-chloropropane
molecule explained. What do the number and values of the chemical
shifts from the c-13 carbon-13 NMR spectrum tell us about the
2-chloropropane
molecule? explaining the decoupled carbon-13 NMR spectrum of
2-chloropropane with a detailed diagram of all the uncoupled C-13 chemical
shifts and intensities
Links associated
with
2-chloropropane
The
infrared spectrum of 2-chloropropane
The mass
spectrum of 2-chloropropane
The
H-1 NMR spectrum of 2-chloropropane
The chemistry of HALOGENOALKANES (haloalkanes)
revision notes INDEX
C-13
NMR spectroscopy index
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