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Interpreting and explaining t he
1H NMR spectrum of 1-chloropropane CH3CH2CH2Cl
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Dr Phil Brown GRIC, 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 1H proton NMR spectrum of 1-chloropropane
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1H NMR spectrum of
CH3CH2CH2Cl
LINKS associated
with 1-chloropropane
The
chemistry of organic halogen compounds
This is a BIG website, please take time to explore it
H-1 proton NMR spectroscopy -
spectra index
Isomers of molecular formula
C3H7X (where
X =
F, Cl, Br or I)
Practise exam questions
based on the 1H NMR spectrum of 1-chloropropane
Introductory note on the 1H NMR spectra of 1-chloropropane
Students and teachers please note my explanation of the
proton NMR spectrum of 1-chloropropane is designed for advanced, but
pre-university, chemistry courses.
The chemical shift
δ splitting pattern effects for
1-chloropropane are
confined to a proton spin-spin
coupling effects analysed using the n+1 rule for adjacent
non-equivalent proton fields (n is the number of neighbouring
protons in a non-equivalent different chemical environment for the
1-chloropropane molecule).
It is assumed that the integrated intensities of the
1H
NMR δ
chemical shifts give the ratio of the protons in the different
non-equivalent chemical environments of the 1-chloropropane molecule.
The most common solvent used for investigating the 1H NMR
spectrum of compounds like 1-chloropropane, is CDCl3 and other
deuterated solvents to avoid confusion with a 1H NMR
signal, 2D (2H) has a different NMR chemical
shift.
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 - 1-chloropropane here.
The chemical shifts quoted in ppm on the diagram of
the H-1 NMR spectrum of 1-chloropropane 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 1-chloropropane molecule.
1-chloropropane C3H7Cl
The molecular structure and naming of haloalkanes
Interpreting the
H-1 NMR spectrum of
1-chloropropane
In terms of spin-spin coupling from the possible proton magnetic orientations,
for 1-chloropropane I
have only considered the interactions of
non-equivalent protons on adjacent carbon atoms
e.g. -CH2-CH3,
or R-CH2-CH2-X
protons.
For relatively simple molecules, the low
resolution H-1 NMR spectrum of 1-chloropropane is a good starting point
(low resolution diagram above).
The hydrogen atoms (protons) of 1-chloropropane occupy
3
different chemical environments so that the low resolution NMR
spectra should show 3 principal peaks of different H-1 NMR chemical shifts (diagram above for
1-chloropropane).
CH3CH2CH2Cl
Note the proton ratio 3:2:2 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 1-chloropropane.
Although there are 7 hydrogen atoms in the molecule,
there are only 3 possible different chemical
environments for the hydrogen atoms in 1-chloropropane molecule.
The integrated signal proton ratio 3:2:2 observed
in the low/high resolution H-1 NMR spectrum, corresponds with
the structural formula of 1-chloropropane.
The high resolution 1H NMR
spectrum of 1-chloropropane
All low and high resolution spectra of
1-chloropropane
show 3 groups of proton resonances and in the 3:2:2 ratio expected from the
formula of 1-chloropropane.
The ppm quoted on the diagram represent the peak
of resonance intensity for a particular proton group in the
molecule of 1-chloropropane - 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 1-chloropropane below.
So, using the chemical shifts and applying the
n+1 rule to
1-chloropropane
and make some predictions using some colour coding! (In problem
solving you work the other way round!)
(a) 1H
Chemical shift 0.85 ppm, CH3 protons: CH3CH2CH2Cl
The methyl resonance is split by the
adjacent CH2 protons into a 1:2:1 triplet
(n+2 = 3).
Evidence for the presence of a CH2 group
in the molecule of 1-chloropropane
(b) 1H
Chemical shift 1.61 ppm, CH2 protons: CH3CH2CH2Cl
The CH2 resonance is split by
the adjacent CH2 and CH3
protons into a 1:5:10:10:5:1 sextet (n+5 = 6).
Evidence for the presence of a CH3CH2CH2 group
in the molecule of 1-chloropropane
(c) 1H
Chemical shift 3.30, CH2 protons : CH3CH2CH2Cl
The methyl resonance is split by the
adjacent CH2 protons into a 1:2:1 triplet
(n+2 = 3).
Evidence for the presence of a 2nd CH2 group
in the molecule of 1-chloropropane
Note the decreasing (more
down field) effect on the 1H chemical shift as the
proton is further from the more electronegative oxygen and
nitrogen bromine chlorine atoms 1-chloropropane.
Summary of the
1H NMR spectrum
of 1-chloropropane and extra comments
A structured breakdown of the ¹H NMR
spectrum of 1-chloropropane (CH3CH2CH2Cl), tailored for
clarity, exam alignment, and misconception-busting.
Molecular Context
of the 1H NMR spectrum of 1-chloropropane
1-chloropropane is a primary haloalkane with three
distinct proton environments:
- CH3 (methyl group)
- CH2 (central methylene)
- CH2Cl (methylene adjacent to chlorine)
Chemical Shifts, Origins
and Integration for
the 1H NMR spectrum of 1-chloropropane
| Chemical Shift
(ppm) |
Proton Type |
Environment |
Splitting Pattern |
Integration |
| ~3.4–3.6, 3.30 ppm |
CH2Cl |
Deshielded by electronegative
Cl |
Triplet (2H) |
2 |
| ~1.5–1.7, 1.61 ppm |
CH2 |
Between CH3 and CH3Cl |
Sextet (2H) |
2 |
| ~0.9–1.0, 0.85 ppm |
CH3 |
Terminal methyl group |
Triplet (3H) |
3 |
CH3CH2CH2Cl
Note: Exact shifts may vary slightly
depending on solvent and instrument, but the pattern remains consistent.
Note: The sextet arises from coupling
with both neighbouring CH3 and CH2 groups (n+1
rule, n = 5, so 6 lines), though in practice
it may appear as a multiplet due to overlapping couplings.
Common Misconceptions
about
the 1H NMR spectrum of 1-chloropropane
(see also below)
- Assuming only functional groups give signals:
Even simple alkyl chains show distinct environments due to proximity
effects.
- Misidentifying the CH2 signals: Students often
confuse the central CH2 with the CH2Cl due to similar integration —
chemical shift and splitting are key.
- Expecting symmetrical splitting: The central
CH₂ may show complex splitting.
Exam Tips
for
questions involving the 1H NMR spectrum of 1-chloropropane
(see also above)
- Always count proton environments:
1-chloropropane has three, not two — crucial for
peak prediction.
- Use integration ratios: 3:2:2 confirms
CH3–CH2–CH2Cl structure.
- Mention chlorine’s effect: It deshields
adjacent protons, shifting CH₂Cl downfield.
- Apply the n+1 rule carefully: Consider both
adjacent groups when predicting multiplicity.
- Compare with isomers: 2-chloropropane shows
only two signals — a great contrast for
multi-choice
The splitting pattern from proton
spin-spin coupling effects is analysed using the n+1 rule for
adjacent non-equivalent proton fields (n is the number of
neighbouring protons in a non-equivalent different chemical
environment).
|
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 |
|
1 |
|
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2
creates a triplet |
|
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|
1 |
|
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 |
|
1 |
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4
creates a quintet |
|
|
1 |
|
4 |
|
6 |
|
4 |
|
1 |
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5
creates a sextet |
|
1 |
|
5 |
|
10 |
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10 |
|
5 |
|
1 |
|
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6
creates a septet |
1 |
|
6 |
|
15 |
|
20 |
|
15 |
|
6 |
|
1 |
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QUESTIONS
Advanced A-level chemistry - practise exam questions on
the 1H proton
NMR spectrum
of 1-chloropropane
Jot
down your responses and check out the answers:
ANSWERS
If you think there are
any errors, please email me asap at
chem55555@hotmail.com
I don't mind if students/teachers do a selected printout
of these questions and answers.
Q1
How many principal 1H NMR resonances would you expect
for 1-chloropropane? and what integrated proton ratios
would observe?
Q2
(a) Are any of the groups of protons on different carbon
atoms equivalent to each other?
(b) What evidence might you observe to suggest a
propyl group in the molecule of 1-chloropropne?
Q3
Why is there such a significance difference in the
chemical shifts of the two CH2 groups
respectively?
Q4
What difference, if any, would you see in the 1H NMR
spectrum if D2O was added to the sample of
1-chloropropane dissolved in CDCl3 solvent?
Jot
down your responses and check out the answers:
ANSWERS
If you think there are
any errors, please email me asap at
chem55555@hotmail.com
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Key words & phrases:
C3H7Cl
CH3CH2CH2Cl Interpreting the proton H-1 NMR spectra of 1-chloropropane, low resolution & high resolution proton
nmr spectra of 1-chloropropane, H-1 nmr spectrum of 1-chloropropane, understanding the
hydrogen-1 nmr spectrum of 1-chloropropane, explaining the line splitting patterns from
spin-spin coupling in the
high resolution H-1 nmr spectra of 1-chloropropane, revising the H-1 nmr spectrum of
1-chloropropane,
proton nmr of 1-chloropropane, ppm chemical shifts of the H-1 nmr spectrum of
1-chloropropane,
explaining and analyzing spin line splitting in the H-1 nmr spectrum, how
to construct the diagram of the H-1 nmr spectrum of 1-chloropropane, how to work out the
number of chemically different protons in the structure of the 1-chloropropane organic
molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR
spectrum of 1-chloropropane using the n+1 rule to explain the spin - spin coupling splitting in the proton nmr spectrum of 1-chloropropane deducing the nature of the protons
from the chemical shifts ppm in the H-1 nmr spectrum of 1-chloropropane
examining the 1H nmr spectrum of 1-chloropropane analysing the 1-H nmr spectrum of
1-chloropropane how do you sketch and interpret the H-1 NMR spectrum of
1-chloropropane
interpreting interpretation of the 1H proton spin-spin coupling causing line
splitting in the NMR spectrum of 1-chloropropane
assignment of chemical shifts in the
proton 1H NMR spectrum of 1-chloropropane formula explaining spin-spin coupling for line splitting
of n-propyl chloride
How do you interpret the H-1 NMR spectrum of
1-chloropropane How to interpret
the H-1 NMR spectrum of 1-chloropropane Explanatory diagram of the chemical
shifts of the 1H H-1 proton NMR spectrum of the 1-chloropropane
molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the
proton NMR spectrum of 1-chloropropane. How to explain the H-1 NMR spectrum of
1-chloropropane. The chemical shifts and integrated values of the proton ratios in the 1-H NMR
spectrum of the 1-chloropropane molecule. How to work out the molecular
structure of the 1-chloropropane molecule from its proton NMR spectrum. The uses
and distinctive features of the proton NMR spectrum of the
1-chloropropane
molecule explained. What does the H-1 proton NMR spectrum chemical
shifts tell us about the
structure and properties of the 1-chloropropane
molecule? explaining the spin-spin proton coupling effects in the 1H
NMR spectrum of 1-chloropropane. diagram explaining the proton splitting pattern produced from the
n+1 rule and the theoretical ratio of chemical shift and
values of intensities for the proton NMR spectrum lines of 1-chloropropane
Links associated
with
1-chloropropane
The
infrared spectrum of 1-chloropropane
The mass
spectrum of 1-chloropropane
(propyl
chloride)
The
C-13 NMR spectrum of 1-chloropropane
The chemistry of HALOGENOALKANES (haloalkanes)
revision notes INDEX
H-1 proton NMR spectroscopy index
(Please
read 8 points at the top of the 1H NMR index page)
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the spectroscopy of 1-chloropropane - its 1H proton NMR spectrum,
detailed analysis, diagnostic features, data analysed, useful spectra comments are
suitable for use of pre-university students studying AQA advanced level
chemistry, Edexcel advanced level chemistry, OCR advanced level
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1st year undergraduate students of chemistry.
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ANSWERS
If you think there are
any errors, please email me asap at
chem55555@hotmail.com
Q1
How many principal 1H NMR resonances would you expect
for 1-chloropropane? and what integrated proton ratios
would observe?
ANSWERS
For CH3CH2CH2Cl you
have three different 1H chemical environments, so you
would expect to observe three different 1H NMR chemical
shifts, which you do!
From the formula you would expect an integrated
proton signal ratio of 3:2:2.
Q2
(a) Are any of the groups of protons on different carbon
atoms equivalent to each other?
(b) What evidence might you observe to suggest a
propyl group in the molecule of 1-chloropropne?
ANSWERS
(a) All the groups of protons are in different
chemical environments.
(b) Therefore the central CH2 protons
resonance can be split by the CH3 and CH2 protons on
either side, so from the n+1 rule, you would expect to
see a sextet - which you do.
Q3
Why is there such a significance difference in the
chemical shifts of the two CH2 groups
respectively?
ANSWER
The much more electronegative chlorine atom (compared
to carbon) produces a significant down field effect on
the CH2 next to the chlorine atom, i.e. a significant
increase in the 1H NMR chemical shift.
Note that it has the same, but less significant
effect on the CH2 protons adjacent to the end
CH3 group.
Q4
What difference, if any, would you see in the 1H NMR
spectrum if D2O was added to the sample of
1-chloropropane dissolved in CDCl3 solvent?
ANSWER
No effect at all, there are
no labile protons e.g. that would see in alcohols (OH)
or amines (NH).
If you think there are
any errors, please email me asap at
chem55555@hotmail.com
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