Advanced Organic Chemistry: 1H NMR spectrum of 2-methylpropan-2-ol (CH3)3COH

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Interpreting the 1H NMR spectrum of 2-methylpropan-2-ol (tert-butyl alcohol)

[Author ©  Dr WP 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 spectrum of 2-methylpropan-2-ol [updated October 24th 2025]

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H-1 proton NMR spectroscopy - spectra index

Introductory note on the 1H NMR spectra of 2-methylpropan-2-ol

Students and teachers please note my explanation of the proton NMR spectrum of 2-methylpropan-2-ol is designed for advanced, but pre-university, chemistry courses.

The chemical shift δ splitting pattern effects for 2-methylpropan-2-ol 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 2-methylpropan-2-ol 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 2-methylpropan-2-ol molecule.

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

C4H10O (CH3)3COH low and high resolution 1H proton nmr spectrum of 2-methylpropan-2-ol analysis interpretation of chemical shifts ppm spin spin line splitting diagram H1 H-1 nmr for tert-butyl alcohol 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 - 2-methylpropan-2-ol here.

The chemical shifts quoted in ppm on the diagram of the H-1 NMR spectrum of 2-methylpropan-2-ol 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 2-methylpropan-2-ol molecule.

2-methylpropan-2-ol   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 ethers

Interpreting the H-1 NMR spectrum of 2-methylpropan-2-ol

In terms of spin-spin coupling from the possible proton magnetic orientations, for 2-methylpropan-2-ol I have only considered the interactions of non-equivalent protons on adjacent carbon atoms e.g. -CH2-CH3, protons, but this is not the case here.

For relatively simple molecules, the low resolution H-1 NMR spectrum of 2-methylpropan-2-ol is a good starting point (low resolution diagram above).

The hydrogen atoms (protons) of 2-methylpropan-2-ol occupy 2 different chemical environments so that the low/high resolution NMR spectra should show 2 principal peaks of different H-1 NMR chemical shifts (diagram above for 2-methylpropan-2-ol).

(CH3)3COH

Note the proton ratio 9:1 of the 2 colours of the protons in the 2 chemically different environments

Just two chemical shifts (a) to (b) on the H-1 NMR spectrum diagram for 2-methylpropan-2-ol.

Although there are 10 hydrogen atoms in the molecule, there are only 2 possible different chemical environments for the hydrogen atoms in 2-methylpropan-2-ol molecule.

The integrated signal proton ratio 9:1 observed in the high resolution H-1 NMR spectrum, corresponds with the structural formula of 2-methylpropan-2-ol.

No splitting is observed for 1H NMR spectrum of 2-methylpropan-2-ol.

(a) 1H Chemical shift 1.26 ppm for the methyl protons: (CH3)3COH

All 9 methyl protons are equivalent to each other, they inhabit the same chemical environment and so give the same H-1 NMR shift of 1.26 ppm.

These are all equivalent protons in the same chemical environment and their fields cannot split each other, hence the singlet for the methyl group protons.

(b) 1H Chemical shift 2.01 ppm for the hydroxyl proton: (CH3)3COH

Note that the electronegative oxygen atom produces a much greater H-1 NMR shift on the H or the C-O-H grouping, typical of molecules like alcohols.

An important note about the hydroxyl group on 2-methylpropan-2-ol (for pre-university students):

(i) Unless the alcohol is completely free of water (difficult), the hydrogen on the -O-H hydroxyl group and any hydrogens on the adjacent carbon don't interact to produce any spin-spin splitting. Therefore the -OH peak shows up as a singlet and you don't usually have to consider its effect on any hydrogen atoms, if present on the adjacent carbon atom (C-OH), and, neither do you have to consider the splitting effect of adjacent C-H protons on the hydrogen of the OH group.

(ii) However, in the case of 2-methylpropan-2-ol there is no adjacent proton (on a neighbouring atom) to interact with the methyl protons or the hydroxyl proton because of this particular tertiary alcohol structure.

The C of the C-OH grouping is not attached to any proton.

EXTRA NOTE on why the OH proton chemical shift is usually observed as a singlet in alcohols like 2-methylpropan-2-ol and how deuterium oxide can be used to identify the peak caused by the hydroxyl proton

Although extremely weak acids, there is constant exchanging of protons between alcohol molecules (R = alkyl groups of 2-methylpropan-2-ol).

R-O-H  +  H-O-R    R-O-H  +  H-O-R

The rate of proton transfer is increased by traces of water.

R-O-H  +  H-O-H    R-O-H  +  H-O-H

This cannot happen with the non-acidic C-H protons of alkyl groups in alcohols like 2-methylpropan-2-ol.

This rapid proton transfer interferes with the field splitting effects of the hydroxyl O-H protons and carbon C-H protons and the spin-spin coupling effects disappear.

This phenomena can be used to identify the O-H proton resonance from other C-H proton resonances in hydroxyl molecules like 2-methylpropan-2-ol.

If deuterium oxide (D2O, where D = 2H) is added to the NMR sample, the 1H protons are rapidly replaced by 2H protons in the 2-methylpropan-2-ol molecule.

R-O-H  +  D-O-D    R-O-D  +  H-O-D

The 2H chemical shift frequency is different to the 1H chemical shift frequency, so the effect of D2O is to remove the chemical shift for the OH proton from the 1H NMR spectrum of 2-methylpropan-2-ol, thereby identifying the original 1H chemical shift as belonging to the hydroxyl group O-H proton and not a C-H proton of the 2-methylpropan-2-ol molecule.

Key points about the 1H NMR spectrum of 2-methylpropan-2-ol

The ¹H NMR spectrum of 2-methylpropan-2-ol shows two distinct signals: a sharp singlet for the methyl protons and a broad singlet for the hydroxyl proton.

Key ¹H NMR Features of 2-Methylpropan-2-ol

2-Methylpropan-2-ol (tert-butanol) has the formula (CH3)3COH.

It contains two types of hydrogen environments:

Chemical Shift (δ, ppm) Integration Multiplicity Proton Type Environment
~1.2 ppm, 1.26 ppm 9H Singlet CH3 Three equivalent methyl groups (tert-butyl)
~2.5–2.8 ppm, 2.01 ppm 1H Broad singlet OH Hydroxyl proton (exchangeable)

Notes:

  • The methyl protons are equivalent due to the molecule’s symmetry.
  • The OH proton is exchangeable and may shift or disappear with D₂O shake or in acidic/basic conditions.

Common Misconceptions in Exams

  • Expecting splitting between OH and CH3: In practice, OH protons often do not couple due to rapid exchange, especially in protic solvents.
  • Misidentifying the broad OH peak: Students may confuse it with impurities or ignore it entirely.
  • Assuming all alcohols show the same OH shift: The OH chemical shift varies with solvent, concentration, and temperature.
  • Overlooking integration: The 9:1 ratio is diagnostic for tert-butyl alcohol; misreading this can lead to incorrect structural proposals.

Exam Revision Tips

  • Use integration ratios: A 9:1 ratio strongly suggests a tert-butyl group with a single OH.
  • Check multiplicity carefully: Singlets for both peaks indicate no coupling—consistent with symmetry and exchange.
  • Practice D2O shake interpretation: Disappearance of the OH peak confirms its identity.
  • Compare with other alcohols: Primary and secondary alcohols show different splitting and integration patterns.
  • Annotate spectra: Label chemical shifts, integration, and multiplicity to build interpretation fluency.

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 2-methylpropan-2-ol.
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 (CH3)3COH Interpreting the proton H-1 NMR spectra of 2-methylpropan-2-ol, low resolution & high resolution proton nmr spectra of 2-methylpropan-2-ol, H-1 nmr spectrum of 2-methylpropan-2-ol, understanding the hydrogen-1 nmr spectrum of 2-methylpropan-2-ol, explaining the line splitting patterns from spin-spin coupling  in the high resolution H-1 nmr spectra of 2-methylpropan-2-ol, revising the H-1 nmr spectrum of 2-methylpropan-2-ol, proton nmr of 2-methylpropan-2-ol, ppm chemical shifts of the H-1 nmr spectrum of 2-methylpropan-2-ol, 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 2-methylpropan-2-ol, how to work out the number of chemically different protons in the structure of the 2-methylpropan-2-ol organic molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR spectrum of 2-methylpropan-2-ol using the n+1 rule to explain the spin - spin coupling ine splitting in the proton nmr spectrum of 2-methylpropan-2-ol deducing the nature of the protons from the chemical shifts ppm in the H-1 nmr spectrum of 2-methylpropan-2-ol examining the 1H nmr spectrum of  2-methylpropan-2-ol analysing the 1-H nmr spectrum of 2-methylpropan-2-ol how do you sketch and interpret the H-1 NMR spectrum of 2-methylpropan-2-ol interpreting interpretation of the 1H proton spin-spin coupling causing line splitting in the NMR spectrum of 2-methylpropan-2-ol  assignment of chemical shifts in the proton 1H NMR spectrum of 2-methylpropan-2-ol formula explaining spin-spin coupling for line splitting in in tert-butyl alcohol How do you interpret the H-1 NMR spectrum of 2-methylpropan-2-ol How to interpret the H-1 NMR spectrum of 2-methylpropan-2-ol Explanatory diagram of the chemical shifts of the 1H H-1 proton NMR spectrum of the 2-methylpropan-2-ol molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the proton NMR spectrum of 2-methylpropan-2-ol. How to explain the H-1 NMR spectrum of 2-methylpropan-2-ol. The chemical shifts and  integrated values of the proton ratios in the 1-H NMR spectrum of the 2-methylpropan-2-ol molecule. How to work out the molecular structure of the 2-methylpropan-2-ol molecule from its proton NMR spectrum. The uses and distinctive features of the proton NMR spectrum of the 2-methylpropan-2-ol molecule explained. What does the H-1 proton NMR spectrum chemical shifts tell us about the structure and properties of the 2-methylpropan-2-ol molecule? explaining the spin-spin proton coupling effects in the 1H NMR spectrum of 2-methylpropan-2-ol. diagram explaining the proton splitting pattern produced from the n+1 rule and the theoretical ratio of chemical shift and values of intensities for the proton NMR spectrum lines of 2-methylpropan-2-ol

Links associated with 2-methylpropan-2-ol

The infrared spectrum of 2-methylpropan-2-ol

The mass spectrum of 2-methylpropan-2-ol

The C-13 NMR spectrum of 2-methylpropan-2-ol

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