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Advanced Organic Chemistry: 1H NMR spectrum of methoxyethane

Interpreting the H-1 hydrogen-1 (proton) NMR spectrum of methoxyethane

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 methoxyethane

See also comparing the infrared, mass, 1H NMR and 13C NMR spectra of the 3 isomers of C3H8O

C3H8O CH3OCH2CH3 low and high resolution 1H proton nmr spectrum of methoxyethane analysis interpretation of chemical shifts ppm spin spin line splitting diagram H1 H-1 nmr for ethyl methyl ether explaining spin-spin coupling for line splitting doc brown's advanced organic chemistry revision notes

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 - methoxyethane here.

The chemical shifts quoted in ppm on the diagram of the H-1 NMR spectrum of methoxyethane 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 methoxyethane molecule.

Methoxyethane  alcohols and ether structure and naming (c) doc b  alcohols and ether structure and naming (c) doc b  alcohols and ether structure and naming (c) doc b  alcohols and ether structure and naming (c) doc b

Interpreting the H-1 NMR spectrum of methoxyethane

In terms of spin-spin coupling from the possible proton magnetic orientations, for methoxyethane I have only considered the interactions of non-equivalent protons on adjacent carbon atoms e.g. -CH2-CH3 protons here.

For relatively simple molecules, the low resolution H-1 NMR spectrum of methoxyethane is a good starting point (low resolution diagram above) from which you can deduce ....

,,, the hydrogen atoms (protons) of methoxyethane 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 methoxyethane).

CH3OCH2CH3

Note the proton ratio 3:2:3 of the three colours of the protons in the three chemically different environments.  Chemical shifts (b), (a) and (c) on the H-1 NMR spectrum diagram for methoxyethane.

Although there are 8 hydrogen atoms in the molecule, there are only 3 possible different chemical environments for the hydrogen atoms in methoxyethane molecule.

The integrated signal proton ratio 3:2:3 observed in the high resolution H-1 NMR spectrum, corresponds with the structural formula of methoxyethane.

The high resolution 1H NMR spectrum of methoxyethane

All low and high resolution spectra of methoxyethane show 3 groups of proton resonances and in the 3:2:3 ratio expected from the formula of methoxyethane.

The ppm quoted on the diagram represent the peak of resonance intensity for a particular proton group in the molecule of methoxyethane - 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 methoxyethane below.

So, using the chemical shifts and applying the n+1 rule to methoxyethane and make some predictions using some colour coding! (In problem solving you work the other way round!)

(a) 1H Chemical shift of methyl protons 3.25 ppm: CH3OCH2CH3

This proton resonance is not split by other protons - non are on an adjacent carbon atoms, so just a singlet is observed,

Evidence for the presence of an alkyl group not connected to another atom with protons bonded to it in the molecule of methoxyethane

(b) 1H Chemical shift of CH2 protons 3.52 ppm: CH3OCH2CH3

This proton resonance is split into a 1:3:3:1 quartet by the adjacent methyl protons (n+1 = 4).

Evidence for the presence of a methyl group in the molecule of methoxyethane

(c) 1H Chemical shift of methyl protons 1.42 ppm: CH3OCH2CH3

This proton resonance is split into a 1:2:1 triplet by the adjacent CH2 protons (n+1 = 3).

Evidence for the presence of a CH2 group in the molecule of methoxyethane

Note the decreasing effect on the 1H chemical shift as the proton is further from the more electronegative oxygen atom in methoxyethane.

Comparing the infrared, mass, 1H NMR and 13C NMR spectra of the 3 isomers of C3H8O

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 propan-1-ol, propan-2-ol and methoxyethane image sizes.

infrared spectrum of ethoxyethane wavenumbers cm-1 functional group detection fingerprint pattern identification of  diethyl ether doc brown's advanced organic chemistry revision notes I wasn't able to obtain an infrared spectrum for methoxyethane, so I've added the infrared spectrum of ethoxyethane to enable a few comparisons with two aliphatic alcohols

Comparing the infrared spectra of propan-1-ol, propan-2-ol and methoxyethane

Propan-1-ol, propan-2-ol and methoxyethane are structural isomers of molecular formula C3H8O

Propan-1-ol, propan-2-ol and methoxyethane exemplify infrared spectra of the lower members of the homologous series of aliphatic alcohols and ethers

INFRARED SPECTRA (above): There are, as expected, differences in the fingerprint region at wavenumbers 1500 to 400 cm-1, but most absorptions for all three molecules are the various C-O and the many C-H vibrational modes. However, there is one characteristic distinguishing absorption only present in the infrared spectra of alcohols, but not in ethers, that is the broad O-H stretching vibration peaking at ~3350 cm-1. There is also another broad absorption band (origin?) peaking at ~650 cm-1 in the alcohol spectra, but not in the ether spectra.

Comparing the mass spectra of propan-1-ol, propan-2-ol and methoxyethane

Propan-1-ol, propan-2-ol and methoxyethane are structural isomers of molecular formula C3H8O

Propan-1-ol, propan-2-ol and methoxyethane exemplify the mass spectra of the lower members of the homologous series of aliphatic alcohols and ethers

MASS SPECTRA (above): The base ion peaks are m/z 45 for propan-2-ol and methoxyethane, but that of propan-1-ol is m/z 31. Many of the fragmentation ions are common to all three spectra. The m/z 45 ion is peak is much smaller in the propan-1-ol spectrum compared to the other two.

Comparing the 1H proton NMR spectra of propan-1-ol, propan-2-ol and methoxyethane

Propan-1-ol, propan-2-ol and methoxyethane are structural isomers of molecular formula C3H8O

Propan-1-ol, propan-2-ol and methoxyethane exemplify the 1H proton NMR spectra of the lower members of the homologous series of aliphatic alcohols and ethers

1H NMR SPECTRA (above): The 1H NMR spectra of all three molecules give different integrated proton ratios for the different 1H chemical environments i.e. the proton ratios are as follows: propan-1-ol 3:2:2:1; propan-2-ol 6:1:1 and methoxyethane 3:2:3. Therefore, all three can be distinguished by their 1H NMR spectra. Methoxyethane shows typical triplet and quartet splitting patterns of an 'isolated' ethyl group with no other C-H adjacent protons..

Comparing the carbon-13 NMR spectra of propan-1-ol, propan-2-ol and methoxyethane

Propan-1-ol, propan-2-ol and methoxyethane are structural isomers of molecular formula C3H8O

Propan-1-ol, propan-2-ol and methoxyethane exemplify the carbon-13 NMR spectra of members of  the lower members of the homologous series of aliphatic alcohols and ethers

13C NMR SPECTRA (above): The 13C NMR spectra of propan-1-ol and methoxyethane show three different 13C NMR chemical shifts, but propan-2-ol can be distinguished from the other two by exhibiting only two chemical shift lines. You would need other spectral data to distinguish propan-1-ol and methoxyethane.

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: C3H8O CH3OCH2CH3 Interpreting the proton H-1 NMR spectra of methoxyethane, low resolution & high resolution proton nmr spectra of methoxyethane, H-1 nmr spectrum of methoxyethane, understanding the hydrogen-1 nmr spectrum of methoxyethane, explaining the line splitting patterns from spin-spin coupling  in the high resolution H-1 nmr spectra of methoxyethane, revising the H-1 nmr spectrum of methoxyethane, proton nmr of methoxyethane, ppm chemical shifts of the H-1 nmr spectrum of methoxyethane, 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 methoxyethane, how to work out the number of chemically different protons in the structure of the methoxyethane organic molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR spectrum of methoxyethane using the n+1 rule to explain the spin - spin coupling ine splitting in the proton nmr spectrum of methoxyethane deducing the nature of the protons from the chemical shifts ppm in the H-1 nmr spectrum of methoxyethane examining the 1H nmr spectrum of  methoxyethane analysing the 1-H nmr spectrum of methoxyethane how do you sketch and interpret the H-1 NMR spectrum of methoxyethane interpreting interpretation of the 1H proton spin-spin coupling causing line splitting in the NMR spectrum of methoxyethane  assignment of chemical shifts in the proton 1H NMR spectrum of methoxyethane formula explaining spin-spin coupling for line splitting for ethyl methyl ether spectrum of methoxyethane methyl ethyl ether CH3CH2OCH3

isomer of molecular formula C3H8O Molecular structure diagram of the proton NMR diagram for the 1H NMR spectrum of methoxyethane. The proton ratio in the 1H NMR spectrum of methoxyethane. Deducing the number of different chemical environments of the protons in the methoxyethane molecule from the 1H chemical shifts in the hydrogen-1 NMR spectrum of methoxyethane. Analysing the high resolution 1H NMR spectrum of methoxyethane. Analysing the low resolution 1H NMR spectrum of methoxyethane. You may need to know the relative molecular mass of methoxyethane to deduce the molecular formula from the proton ratio of the 1H NMR spectrum of methoxyethane. Revision notes on the proton NMR spectrum of methoxyethane. Matching and deducing the structure of the methoxyethane molecule from its hydrogen-1 NMR spectrum. Proton NMR spectroscopy of aliphatic ethers, 1H NMR spectra of methoxyethane, an isomer of molecular formula C3H8O


Links associated with methoxyethane

H-1 proton NMR spectroscopy index  (Please read 8 points at the top of the 1H NMR index page)

The infrared spectrum of methoxyethane

The mass spectrum of methoxyethane

The C-13 NMR spectrum of methoxyethane

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