|
Interpreting the
H-1 hydrogen-1 (proton) NMR spectrum of 1,1,2-trichloroethane
Doc
Brown's Chemistry Advanced Level Pre-University Chemistry Revision Study
Notes for UK IB KS5 A/AS GCE advanced A level organic chemistry students US
K12 grade 11 grade 12 organic chemistry courses involving molecular
spectroscopy analysing H-1 NMR spectra of 1,1,2-trichloroethane
email doc
brown
Use your
mobile phone or ipad etc. in 'landscape' mode
This is a BIG
website, you need to take time to explore it
H-1 proton NMR spectroscopy -
spectra index
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 - 1,1,2-trichloroethane here.
The chemical shifts quoted in ppm on the diagram of
the H-1 NMR spectrum of 1,1,2-trichloroethane 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 1,1,2-trichloroethane molecule.
1,1,2-trichloroethane Cl2CH-CH2Cl
or CHCl2CH2Cl
Interpreting the
H-1 NMR spectrum of
1,1,2-trichloroethane
In terms of spin-spin coupling from the possible proton magnetic orientations,
for 1,1,2-trichloroethane I
have only considered the interactions of
non-equivalent protons on adjacent carbon atoms
e.g. CH-CH2.
For relatively simple molecules, the low
resolution H-1 NMR spectrum of 1,1,2-trichloroethane is a good starting point
(low resolution diagram above).
The hydrogen atoms (protons) of
1,1,2-trichloroethane occupy 2
different chemical environments so that the low resolution NMR
spectra should show 2 principal peaks of different H-1 NMR chemical shifts (diagram above for
1,1,2-trichloroethane).
Cl2CH-CH2Cl
or CHCl2CH2Cl
Note the proton ratio 1:2 of the 2 colours of the protons
in the 2 chemically different proton environments
Chemical shifts (a) to (b) on the H-1 NMR
spectrum diagram for 1,1,2-trichloroethane.
Although there are 3 hydrogen atoms in the molecule,
there are only 2 possible different chemical
environments for the hydrogen atoms in 1,1,2-trichloroethane molecule.
The integrated signal proton ratio 1:2 observed
in the high resolution H-1 NMR spectrum, corresponds with
the structural formula of 1,1,2-trichloroethane.
The high resolution 1H NMR
spectrum of 1,1,2-trichloroethane
The high resolution spectra of
1,1,2-trichloroethane
shows 2 groups of proton resonances and in the 1:2 ratio expected from the
structural
formula of 1,1,2-trichloroethane.
The ppm quoted on the diagram represent the peak
of resonance intensity for a particular proton group in the
molecule of 1,1,2-trichloroethane - 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 1,1,2-trichloroethane below.
So, using the chemical shifts and applying the
n+1 rule to
1,1,2-trichloroethane
and make some predictions using some colour coding! (In problem
solving you work the other way round!)
(a) 1H
Chemical shift 5.76 ppm, CH proton: CHCl2CH2Cl
This resonance is split into a 1:2:1
triplet by the CH2 protons (n+1 = 3).
Evidence for the presence of a CH2 group
in the molecule of 1,1,2-trichloroethane
(b) 1H
Chemical shift 3.96 ppm, CH2 protons: CHCl2CH2Cl
This resonance is split into a 1:1
doublet by the CH proton (n+1 = 2).
Evidence for the presence of a CH group
in the molecule of 1,1,2-trichloroethane
|
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:
C2H3Cl3
Cl2CHCH2Cl CHCl2CH2Cl ClCH2CHCl2 CH2ClCHCl2
Interpreting the proton H-1 NMR spectra of 1,1,2-trichloroethane, low resolution & high resolution proton
nmr spectra of 1,1,2-trichloroethane, H-1 nmr spectrum of 1,1,2-trichloroethane, understanding the
hydrogen-1 nmr spectrum of 1,1,2-trichloroethane, explaining the line splitting patterns from
spin-spin coupling in the
high resolution H-1 nmr spectra of 1,1,2-trichloroethane, revising the H-1 nmr spectrum of
1,1,2-trichloroethane,
proton nmr of 1,1,2-trichloroethane, ppm chemical shifts of the H-1 nmr spectrum of
1,1,2-trichloroethane,
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 1,1,2-trichloroethane, how to work out the
number of chemically different protons in the structure of the
1,1,2-trichloroethane organic
molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR
spectrum of 1,1,2-trichloroethane using the n+1 rule to explain the spin - spin coupling ine
splitting in the proton nmr spectrum of 1,1,2-trichloroethane deducing the nature of the protons
from the chemical shifts ppm in the H-1 nmr spectrum of 1,1,2-trichloroethane
examining the 1H nmr spectrum of 1,1,2-trichloroethane analysing the 1-H nmr spectrum of
1,1,2-trichloroethane
how do you sketch and interpret the H-1 NMR spectrum of 1,1,2-trichloroethane
interpreting interpretation of the 1H proton spin-spin coupling causing line
splitting in the NMR spectrum of 1,1,2-trichloroethane
assignment of chemical shifts in the
proton 1H NMR spectrum of 1,1,2-trichloroethane formula explaining spin-spin
coupling for line splitting for 1,1,2-trichloroethane old names
functional group
Links associated
with 1,1,2-trichloroethane
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)
ALL SPECTROSCOPY INDEXES
All Advanced Organic
Chemistry Notes
Use My Google search site box
Email doc b:
chem55555@hotmail.com
|
