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Interpreting
and explaining the
H-1 (proton) NMR spectrum of iodoethane
(ethyl iodide)
[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 1H NMR spectra of ethylmethylamine
[spectra
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H-1 proton NMR spectroscopy -
spectra index
Introductory note on the 1H NMR spectra of iodoethane
Students and teachers please note my explanation of the
proton NMR spectrum of iodoethane is designed for advanced, but
pre-university, chemistry courses.
The chemical shift
δ splitting pattern effects for
iodoethane 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
iodoethane molecule).
It is assumed that the integrated intensities of the
δ
chemical shifts give the ratio of the protons in the different
non-equivalent chemical environments of the iodoethane molecule.
The most common solvent used for investigating the 1H NMR
spectrum of compounds like iodoethane, is CDCl3 and other
deuterated solvents to avoid confusion with a 1H NMR
signal, 2D (2H) has a different 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 - iodoethane here.
The chemical shifts quoted in ppm on the diagram of
the H-1 NMR spectrum of iodoethane 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 iodoethane molecule.
iodoethane,
C2H5I,
CH3CH2I,
CH3-CH2-I
The molecular structure and naming of haloalkanes
Interpreting the
H-1 NMR spectrum of
iodoethane
In terms of spin-spin coupling from the possible proton magnetic orientations,
for iodoethane I
have only considered the interactions of
non-equivalent protons on adjacent carbon atoms
e.g. -CH2-CH3, protons
etc.
For relatively simple molecules, the low
resolution H-1 NMR spectrum of iodoethane is a good starting point
(low resolution diagram above).
The 5 hydrogen atoms (protons) of iodoethane occupy
2
different chemical environments so that the low resolution NMR
spectra should show 2 principal
1H peaks of different H-1 NMR chemical shifts (diagram above for
iodoethane).
CH3-CH2-I
Note the integrated proton ratio of 3:2 of the 2 colours of the
2 protons of iodoethane
in the 2 chemically different proton environments
Chemical shifts (a) to (b) on the H-1 NMR
spectrum diagram for iodoethane.
Although there are 5 hydrogen atoms in the molecule, the
proton NMR spectrum shows there are only 2 possible different chemical
environments for the hydrogen atoms in iodoethane molecule.
The integrated signal proton ratio 3:2 observed
in the high resolution H-1 NMR spectrum, corresponds with
the structural formula of iodoethane.
The high resolution 1H NMR
spectrum of iodoethane
The high resolution spectra of iodoethane still shows
2 groups of proton resonances and in the 3:2 ratio expected from
the structural formula of iodoethane, but we can now consider
the splitting of resonance lines from the spin-spin coupling in
the molecule of iodoethane.
The ppm quoted on the diagram represent the peak
of resonance intensity for a particular proton group in the
molecule of iodoethane - 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 iodoethane below.
So, using the chemical shifts and applying the
n+1 rule to
iodoethane
and make some predictions using some colour coding! (In problem
solving you work the other way round!)
Resonance
(a) 1H Chemical shift 1.85 ppm: CH3CH2I
The methyl group proton resonance is
split by the CH2 group protons into a 1:2:1
triplet (n+1 = 3).
Evidence for the presence of a CH2 group
in the molecule of iodoethane
Resonance
(b) 1H Chemical shift 3.19 ppm: CH3CH2I
The CH2 group proton
resonance is split by the methyl group protons into a
1:3:3:1 quartet (n+1 = 4).
Evidence for the presence of a CH3 group
in the molecule of iodoethane
Note the decreasing effect on the 1H chemical shift as the
proton is further from the more electronegative oxygen and
nitrogen bromine chlorine atoms iodoethane.
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
iodoethane.
|
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 |
|
|
|
|
|
|
1 |
|
|
|
|
|
|
|
1
creates a doublet |
|
|
|
|
|
1 |
|
1 |
|
|
|
|
|
|
2
creates a triplet |
|
|
|
|
1 |
|
2 |
|
1 |
|
|
|
|
|
3
creates a quartet |
|
|
|
1 |
|
3 |
|
3 |
|
1 |
|
|
|
|
4
creates a quintet |
|
|
1 |
|
4 |
|
6 |
|
4 |
|
1 |
|
|
|
5
creates a sextet |
|
1 |
|
5 |
|
10 |
|
10 |
|
5 |
|
1 |
|
|
6
creates a septet |
1 |
|
6 |
|
15 |
|
20 |
|
15 |
|
6 |
|
1 |
Key words & phrases:
C2H5I
CH3CH2I Interpreting the proton H-1 NMR spectra of iodoethane, low resolution & high resolution proton
nmr spectra of iodoethane, H-1 nmr spectrum of iodoethane, understanding the
hydrogen-1 nmr spectrum of iodoethane, explaining the line splitting patterns from
spin-spin coupling in the
high resolution H-1 nmr spectra of iodoethane, revising the H-1 nmr spectrum of
iodoethane,
proton nmr of iodoethane, ppm chemical shifts of the H-1 nmr spectrum of
iodoethane,
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 iodoethane, how to work out the
number of chemically different protons in the structure of the iodoethane organic
molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR
spectrum of iodoethane using the n+1 rule to explain the spin - spin coupling ine
splitting in the proton nmr spectrum of iodoethane deducing the nature of the protons
from the chemical shifts ppm in the H-1 nmr spectrum of iodoethane
examining the 1H nmr spectrum of iodoethane analysing the 1-H nmr spectrum of
iodoethane
how do you sketch and interpret the H-1 NMR spectrum of iodoethane interpreting
interpretation of the 1H proton spin-spin coupling causing line splitting in the
NMR spectrum of iodoethane
assignment of chemical shifts in the
proton 1H NMR spectrum of iodoethane formula explaining spin-spin coupling for
line splitting for iodoethane
functional group haloalkane
halogenoalkane alkyl halide ethyl iodide
How do you interpret the H-1 NMR spectrum of iodoethane How to interpret
the H-1 NMR spectrum of iodoethane Explanatory diagram of the chemical
shifts of the 1H H-1 proton NMR spectrum of the iodoethane
molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the
proton NMR spectrum of iodoethane. How to explain the H-1 NMR spectrum of
iodoethane. The chemical shifts and integrated values of the proton ratios in the 1-H NMR
spectrum of the iodoethane molecule. How to work out the molecular
structure of the iodoethane molecule from its proton NMR spectrum. The uses
and distinctive features of the proton NMR spectrum of the
iodoethane
molecule explained. What does the H-1 proton NMR spectrum chemical
shifts tell us about the
structure and properties of the iodoethane
molecule? explaining the spin-spin proton coupling effects in the 1H
NMR spectrum of iodoethane. 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 iodoethane
Links associated
with
iodoethane
The chemistry of HALOGENOALKANES (haloalkanes)
revision notes INDEX
The infrared spectrum of iodoethane (ethyl iodide)
The mass spectrum of iodoethane (ethyl iodide)
The C-13 NMR spectrum of
iodoethane (ethyl iodide)
H-1 proton NMR spectroscopy index
(Please
read 8 points at the top of the 1H NMR index page)
ALL SPECTROSCOPY INDEXES
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