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Interpreting
and explaining the
H-1 hydrogen-1 (proton) NMR spectrum of 1-iodo-2-methylpropane
[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 analysis of
1-iodo-2-methylpropane
(1H NMR)
[spectra page updated
Mar 30th 2026 *]
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brown
Re-edit 1H NMR spectrum of
(CH3)2CHCH2I
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Links associated with 1-iodo-2-methylpropane
H-1 proton NMR spectroscopy -
spectra index
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and disclaimer]
See also
comparison of the infrared, mass, 1H NMR and 13C NMR
spectra of the four isomers of C4H9I
Introductory note on the 1H NMR spectrum of 1-iodo-2-methylpropane
(isobutyl iodide)
Students and teachers please note my explanation of the
proton NMR spectrum of 1-iodo-2-methylpropane is designed for advanced, but
pre-university, chemistry spectroscopy courses.
The chemical shift
δ splitting pattern effects for
ethanol 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
ethanol 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-iodo-2-methylpropane molecule.
The most common solvent used for investigating the 1H NMR
spectrum of compounds like 1-iodo-2-methylpropane, 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-iodo-2-methylpropane here.
The chemical shifts quoted in ppm on the diagram of
the H-1 NMR spectrum of 1-iodo-2-methylpropane 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-iodo-2-methylpropane molecule.
1-iodo-2-methylpropane,
(isobutyl iodide),
C4H9I,
(CH3)2CHCH2I
The molecular structure and naming of haloalkanes
Interpreting the
H-1 NMR spectrum of
1-iodo-2-methylpropane
In terms of spin-spin coupling from the possible proton magnetic orientations,
for 1-iodo-2-methylpropane I
have only considered the interactions of
non-equivalent protons on adjacent carbon atoms
e.g. -CH-CH3, -CH-CH2- protons
etc.
For relatively simple molecules, the low
resolution H-1 NMR spectrum of 1-iodo-2-methylpropane is a good starting point
(low resolution diagram above).
The 9 hydrogen atoms (protons) of
1-iodo-2-methylpropane occupy
3
different chemical environments so that the low resolution NMR
spectra should show 3 principal resonance peaks of different H-1 NMR chemical shifts (diagram above for
1-iodo-2-methylpropane).
(CH3)2CHCH2I
Note the
proton ratio 6:2:1 of the 3 colours of the
9 protons of 1-iodo-2-methylpropane
in the 3 chemically different
1H NMR chemical shifts observed.
Chemical shifts δ (a) to (c) on the H-1 NMR
spectrum diagram for 1-iodo-2-methylpropane.
Although there are 9 hydrogen atoms in the molecule, the
proton NMR spectrum shows there are only
3 possible different chemical
environments for the hydrogen atoms in 1-iodo-2-methylpropane molecule.
The integrated proton signal ratio of 6:2:1 observed
in the high resolution H-1 NMR spectrum, corresponds with
the structural formula of 1-iodo-2-methylpropane.
The high resolution 1H NMR spectrum of 1-iodo-2-methylpropane
The high resolution spectra of
1-iodo-2-methylpropane
shows 3 groups of proton resonances and in the 6:2:1 ratio expected from the
structural
formula of 1-iodo-2-methylpropane, but we can now consider the splitting of
resonance lines from the spin-spin coupling in the molecule of
1-iodo-2-methylpropane.
The ppm quoted on the diagram represent the peak
of resonance intensity for a particular proton group in the
molecule of 1-iodo-2-methylpropane - 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-iodo-2-methylpropane below.
So, using the chemical shifts and applying the
n+1 rule to
1-iodo-2-methylpropane
and make some predictions using some colour coding! (In problem
solving you work the other way round!)
1H NMR resonance
(a) 1H Chemical shift δ 1.02 ppm: (CH3)2CHCH2I
This resonance is split into a 1:1
doublet (n+1 = 2) by the adjacent CH proton.
The six methyl protons are all
equivalent due to the symmetry of the
1-iodo-2-methylpropane molecule.
Evidence for the presence of a CH group
in the molecule of 1-iodo-2-methylpropane
1H NMR resonance
(b) 1H
Chemical shift δ 1.74 ppm: (CH3)2CHCH2I
This resonance is split into a nonet (9)
of resonance lines by protons of the two adjacent methyl
groups AND the CH2 group (n+1 = 9).
Evidence for the presence of a (CH3)2CHCH2 grouping
in the molecule of 1-iodo-2-methylpropane
1H NMR resonance
(c) 1H
Chemical shift δ 3.14 ppm: (CH3)2CHCH2I
This resonance is split into a 1:1
doublet (n+1 = 2) by the adjacent CH proton.
Evidence for the presence of a CH group
in the molecule of 1-iodo-2-methylpropane
Note the decreasing effect on the 1H chemical shift as the
proton is further from the more electronegative iodine atom in 1-iodo-2-methylpropane.
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Comparing the infrared, mass, 1H NMR and 13C NMR
spectra of the 4 halogenoalkane isomers of C4H9I
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-iodobutane,
2-iodobutane, 1-iodo-2-methylpropane and 2-iodo-2-methylpropane
image sizes. These four molecules
are structural isomers of molecular formula C4H9I
and
exemplify the infrared, mass, 1H NMR and 13C NMR spectra of lower
aliphatic halogenoalkanes (haloalkanes, alkyl halides,
iodoalkanes, alkyl iodides). |
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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. |
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MASS SPECTRA (above):
All four give the parent molecular ion of m/z 184, but it is
only a relatively tiny peak for 2-iodo-2-methylpropane. All four
give the base ion peak of m/z 57. All four give prominent peaks
for m/z ions 29 and 41 and all give a tiny peak from an ionised
iodine atom at m/z 127. They look quite similar to me and lack a
clear fingerprint fragmentation pattern. |
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1H NMR SPECTRA (above): The 1H NMR spectra of
all three molecules give different proton ratios i.e.1-iodobutane
four peaks 3:2:2:2, 2-iodobutane four peaks 3:3:2:1,
1-iodo-2-methylpropane three peaks 6:2:1 and
2-iodo-2-methylpropane 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-iodobutane and
2-iodobutane show four 13C NMR resonances,
1-iodo-2-methylpropane three 13C NMR resonances and
2-iodo-2-methylpropane only two 13C resonances. Therefore
1-iodo-2-methylpropane and 2-iodo-2-methylpropane can be
distinguished from the other three by their number of resonances
in their 13C NMR spectra, but 1-iodobutane and 2-iodobutane
cannot be distinguished from each other from their number of 13C
NMR resonance lines - other data would be required. |
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) and applied to the 1H NMR spectrum of
1-iodo-2-methylpropane.
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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 |
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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 |
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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 |
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1 |
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5
creates a sextet |
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1 |
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5 |
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10 |
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10 |
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5 |
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1 |
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6
creates a septet |
1 |
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6 |
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15 |
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20 |
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15 |
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6 |
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1 |
Key words & phrases:
isomer
of molecular formula C4H9I
(CH3)2CHCH2I Interpreting the proton H-1 NMR spectra of 1-iodo-2-methylpropane, low resolution & high
resolution proton nmr spectra of 1-iodo-2-methylpropane, H-1 nmr spectrum of
1-iodo-2-methylpropane, understanding the
hydrogen-1 nmr spectrum of 1-iodo-2-methylpropane, explaining the line splitting patterns from
spin-spin coupling in the high resolution H-1 nmr spectra of
1-iodo-2-methylpropane, revising
the H-1 nmr spectrum of 1-iodo-2-methylpropane, proton nmr of
1-iodo-2-methylpropane, ppm chemical shifts of the H-1
nmr spectrum of 1-iodo-2-methylpropane, explaining and analyzing spin spin line splitting in the
H-1 nmr spectrum, how to construct the diagram of the 1H nmr spectrum of
1-iodo-2-methylpropane, how to work out the
number of chemically different protons in the structure of the
1-iodo-2-methylpropane organic
molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR
spectrum of 1-iodo-2-methylpropane using the n+1 rule to explain the spin - spin coupling ine
splitting in the proton nmr spectrum of 1-iodo-2-methylpropane deducing the nature of the protons
from the chemical shifts ppm in the H-1 nmr spectrum of 1-iodo-2-methylpropane
examining the 1H nmr spectrum of 1-iodo-2-methylpropane analysing the 1H nmr spectrum of
1-iodo-2-methylpropane
how do you sketch and interpret the H-1 NMR spectrum of 1-iodo-2-methylpropane
interpreting interpretation of the 1H proton spin-spin coupling causing line
splitting in the NMR spectrum of 1-iodo-2-methylpropane
assignment of chemical shifts in the
proton 1H NMR spectrum of 1-iodo-2-methylpropane formula explaining spin-spin
coupling for line splitting for 1-iodo-2-methylpropane
functional group alkyl iodide alkyl halide haloalkane
halogenoalkane isobutyl iodide Molecular structure diagram of the
proton NMR diagram for the 1H NMR spectrum of 1-iodo-2-methylpropane. The proton ratio in the
1H NMR spectrum of 1-iodo-2-methylpropane. Deducing the number of different chemical
environments of the protons in the 1-iodo-2-methylpropane molecule from the 1H chemical shifts
in the hydrogen-1 NMR spectrum of 1-iodo-2-methylpropane. Analysing the high resolution 1H NMR
spectrum of 1-iodo-2-methylpropane. Analysing the low resolution 1H NMR spectrum of
1-iodo-2-methylpropane. You
may need to know the relative molecular mass of 1-iodo-2-methylpropane to deduce the molecular
formula from the proton ratio of the 1H NMR spectrum of
1-iodo-2-methylpropane. Revision notes
on the proton NMR spectrum of 1-iodo-2-methylpropane. Matching and deducing the structure of
the 1-iodo-2-methylpropane molecule from its hydrogen-1 NMR spectrum.
Proton NMR spectroscopy of halogenoalkanes iodoalkanes,
1H NMR spectra of 1-iodo-2-methylpropane, an isomer of molecular formula
C4H9I
How do you interpret the H-1 NMR spectrum of
1-iodo-2-methylpropane How to interpret
the H-1 NMR spectrum of 1-iodo-2-methylpropane Explanatory diagram of the chemical
shifts of the 1H H-1 proton NMR spectrum of the
1-iodo-2-methylpropane
molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the
proton NMR spectrum of 1-iodo-2-methylpropane. How to explain the H-1 NMR spectrum of
1-iodo-2-methylpropane. The chemical shifts and integrated values of the proton ratios in the 1-H NMR
spectrum of the 1-iodo-2-methylpropane molecule. How to work out the molecular
structure of the 1-iodo-2-methylpropane molecule from its proton NMR spectrum. The uses
and distinctive features of the proton NMR spectrum of the
1-iodo-2-methylpropane
molecule explained. What does the H-1 proton NMR spectrum chemical
shifts tell us about the
structure and properties of the 1-iodo-2-methylpropane
molecule? explaining the spin-spin proton coupling effects in the 1H
NMR spectrum of 1-iodo-2-methylpropane. interpretation
diagram explaining the proton splitting pattern produced from the
n+1 rule and the theoretical ratio of chemical shift
δ and values of
intensities for the proton NMR spectrum lines of 1-iodo-2-methylpropane
Links associated
with
1-iodo-2-methylpropane
The chemistry of HALOGENOALKANES (haloalkanes)
revision notes INDEX
The infrared spectrum of
1-iodo-2-methylpropane (isobutyl iodide)
The mass spectrum of 1-iodo-2-methylpropane (isobutyl
iodide)
The C-13 NMR
spectrum of 1-iodo-2-methylpropane (isobutyl iodide)
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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spectroscopy (on the 1H NMR spectrum of 1-iodo-2-methylpropane) suitable for use of pre-university students studying AQA advanced level
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1st year undergraduate students of chemistry. |
