Advanced Organic Chemistry: 1H NMR spectrum of 1-methoxypropane CH3OCH2CH2CH3

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Interpreting and explaining the H-1 hydrogen-1 (proton) NMR spectrum of 1-methoxypropane CH3OCH2CH2CH3

[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-methoxypropane (1H NMR spectra) [spectra page updated April 1st 2026 *]

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 H-1 proton NMR spectroscopy - spectra index

Introductory note on the 1H NMR spectra of 1-methoxypropane

Students and teachers please note my explanation of the proton NMR spectrum of 1-methoxypropane is designed for advanced, but pre-university, chemistry courses.

The chemical shift δ splitting pattern effects for 1-methoxypropane 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-methoxypropane 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 in the 1-methoxypropane molecule.

The most common solvent used for investigating the 1H NMR spectrum of compounds like 1-methoxypropane, is CDCl3 and other deuterated solvents to avoid confusion with a 1H NMR signal, 2D (2H) has a different chemical shift.

low/high resolution 1H proton nmr spectrum of 1-methoxypropane C4H10O CH3OCH2CH2CH3 analysis interpretation of chemical shifts ppm spin spin line splitting diagram H1 H-1 nmr for methyl propyl 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 - 1-methoxypropane here.

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

1-methoxypropane   C4H10O   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

The molecular structure and naming of aliphatic alcohols and isomeric ethers

Interpreting the H-1 NMR spectrum of 1-methoxypropane

In terms of spin-spin coupling from the possible proton magnetic orientations, for 1-methoxypropane I have only considered the interactions of non-equivalent protons on adjacent carbon atoms e.g. -CH2-CH3, R-CH2-CH- protons etc.

For relatively simple molecules, the low resolution H-1 NMR spectrum of 1-methoxypropane is not a good starting point (low resolution diagram above).

Two resonances are very close together, so you appear to observe a proton ratio of 5:2:3.

However, theoretically, the hydrogen atoms (protons) of 1-methoxypropane occupy 4 different chemical environments so that the high resolution NMR spectra should show 4 principal +H peaks of different H-1 NMR chemical shifts.

CH3OCH2CH2CH3

Note the proton ratio 3:2:2:3 of the 4 colours of the protons in the 4 chemically different environments

Chemical shifts (a) to (d) on the H-1 NMR spectrum diagram for 1-methoxypropane.

Although there are 10 hydrogen atoms in the molecule, theoretically, there are only 4 possible different chemical environments for the hydrogen atoms in 1-methoxypropane molecule.

The high resolution 1H NMR spectrum of 1-methoxypropane

The ppm quoted on the diagram represent the peak of resonance intensity for a particular proton group in the molecule of 1-methoxypropane - 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-methoxypropane below.

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

(a) 1H Chemical shift 3.34 ppm, methyl protons: CH3OCH2CH2CH3

This 1H resonance does not show line splitting because there is no proton on the adjacent oxygen atom.

Evidence for the presence of an 'isolated' CH3 group in the molecule of 1-methoxypropane.

(b) 1H Chemical shift 3.34, CH2 protons: CH3OCH2CH2CH3

Theoretically this 1H resonance is split into a 1:2:1 triplet by the adjacent CH2 group protons (n+2 = 3).

Evidence for the presence of a CH2 group in the molecule of 1-methoxypropane.

It takes an exceptionally high resolution to distinguish between 1H resonance (a, 3.337 ppm) and (b, 3.336 pm).

A triplet and singlet are superimposed on each other - you can actually see this in the spectrum diagram above.

(c) 1H Chemical shift 1.59 ppm, CH2 protons: CH3OCH2CH2CH3

Theoretically this 1H resonance is split into a 1:5:10:10:5:1 sextet by the adjacent CH2 group and CH3 group protons (n+5 = 6).

Evidence for the presence of a second CH2 group in the molecule of 1-methoxypropane.

(d) 1H Chemical shift 0.93 ppm, methyl protons: CH3OCH2CH2CH3

Theoretically this 1H resonance is split into a 1:2:1 triplet by the adjacent CH2 group protons (n+2 = 3).

Evidence for the presence of a second CH2 group in the molecule of 1-methoxypropane.

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

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-methoxypropane.
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: C4H10O CH3OCH2CH2CH3 Interpreting the proton H-1 NMR spectra of 1-methoxypropane, low resolution & high resolution proton nmr spectra of 1-methoxypropane, H-1 nmr spectrum of 1-methoxypropane, understanding the hydrogen-1 nmr spectrum of 1-methoxypropane, explaining the line splitting patterns from spin-spin coupling  in the high resolution H-1 nmr spectra of 1-methoxypropane, revising the H-1 nmr spectrum of 1-methoxypropane, proton nmr of 1-methoxypropane, ppm chemical shifts of the H-1 nmr spectrum of 1-methoxypropane, 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-methoxypropane, how to work out the number of chemically different protons in the structure of the 1-methoxypropane organic molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR spectrum of 1-methoxypropane using the n+1 rule to explain the spin - spin coupling ine splitting in the proton nmr spectrum of 1-methoxypropane deducing the nature of the protons from the chemical shifts ppm in the H-1 nmr spectrum of 1-methoxypropane examining the 1H nmr spectrum of  1-methoxypropane analysing the 1-H nmr spectrum of 1-methoxypropane how do you sketch and interpret the H-1 NMR spectrum of 1-methoxypropane interpreting interpretation of the 1H proton spin-spin coupling causing line splitting in the NMR spectrum of 1-methoxypropane  assignment of chemical shifts in the proton 1H NMR spectrum of 1-methoxypropane formula explaining spin-spin coupling for line splitting for CH3CH2CH2OCH3 methyl propyl ether How do you interpret the H-1 NMR spectrum of 1-methoxypropane How to interpret the H-1 NMR spectrum of 1-methoxypropane Explanatory diagram of the chemical shifts of the 1H H-1 proton NMR spectrum of the 1-methoxypropane molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the proton NMR spectrum of 1-methoxypropane. How to explain the H-1 NMR spectrum of 1-methoxypropane. The chemical shifts and  integrated values of the proton ratios in the 1-H NMR spectrum of the 1-methoxypropane molecule. How to work out the molecular structure of the 1-methoxypropane molecule from its proton NMR spectrum. The uses and distinctive features of the proton NMR spectrum of the 1-methoxypropane molecule explained. What does the H-1 proton NMR spectrum chemical shifts tell us about the structure and properties of the 1-methoxypropane molecule? explaining the spin-spin proton coupling effects in the 1H NMR spectrum of 1-methoxypropane. 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-methoxypropane

Links associated with 1-methoxypropane

The infrared spectrum of 1-methoxypropane (methyl propyl ether)

The mass spectrum of 1-methoxypropane (methyl propyl ether)

The C-13 NMR spectrum of 1-methoxypropane (methyl propyl ether)

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

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