Advanced Organic Chemistry: H-1 NMR spectrum of 2-methylbutane (CH3)2CHCH2CH3

Interpreting the 1H NMR spectrum of 2-methylbutane

[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 - analysing the 1H NMR spectrum of 2-methylbutane  [spectra page updated Mar 13th 2026 *]

* email doc brown * [privacy, cookies & disclaimer policies] * Re-edit 1H NMR spectrum of  CH3CH2CH(CH3)2

Links associated with 2-methylbutane

This is a BIG chemistry website, please take time to explore it

H-1 proton NMR spectroscopy - spectra index

See also comparing the infrared, mass, 1H NMR and 13C NMR spectra of the 3 alkane isomers of C5H12

Introductory note on the 1H NMR spectra of 2-methylbutane

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

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

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

low and high resolution H-1 proton nmr spectrum of 2-methylbutane analysis interpretation of chemical shifts ppm spin spin line splitting diagram H1 1-H nmr for 2-methylbutane 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 shifts, called chemical shifts, depend on the individual (electronic) chemical environment of the hydrogen atoms in an organic molecule - 2-methylbutane here.

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

2-methylbutane C5H12 alkanes structure and naming (c) doc b , alkanes structure and naming (c) doc b , alkanes structure and naming (c) doc b

For more see The molecular structure and naming of alkanes

Interpreting the H-1 NMR spectrum of 2-methylbutane

For relatively simple molecules, the low resolution H-1 NMR spectrum of 2-methylbutane is a good starting point.

The hydrogen atoms (protons) of 2-methylbutane occupy 4 different chemical environments so that the low resolution NMR spectra should show 4 peaks of different H-1 NMR chemical shifts (low resolution diagram above for 2-methylbutane).

(CH3)2CHCH2CH3

Note the integrated proton ratio of 6:1:2:3 of the 4 colours of the protons in the 4 chemically different environments

Although there are 12 hydrogen atoms in the molecule, there only 4 possible 1H chemical environments for the hydrogen atoms in 2-methylbutane molecule.

The proton ratio  6:1:2:3 observed, corresponds with the structural formula of 2-methylbutane.

The high resolution spectrum of 2-methylbutane

All low and high resolution spectra of 2-methylbutane show 4 groups of protons and in the ratio expected from the structural formula of 2-methylbutane.

The ppm quoted on the diagram represent the peak of resonance intensity for a particular proton group in the molecule of 2-methylbutane - 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 2-methylbutane below.

So, using the chemical shifts and applying the n+1 rule to 2-methylbutane

(a) Chemical shift 0.869 ppm, the left-hand 2 x CH3 protons,  (CH3)2CHCH2CH3

This proton resonance is split into a 1:1 doublet by the CH proton (n+1 = 2 = doublet). These methyl groups consist of six chemically equivalent carbon atoms i.e. they have identical chemical environments.

Evidence for the presence of a CH group in the molecule of 2-methylbutane

(b) Chemical shift 1.45 ppm, the lone CH proton,  (CH3)2CHCH2CH3

This proton resonance is split into a nonet (n+1 = 9 because of 2 x CH3 plus CH2)

Evidence for the presence of a  (CH3)2CHCH2 group in the molecule of 2-methylbutane.

The 'blue' methyl groups are identical in the 2-methylbutane molecule i.e. all six protons are in an identical chemical environment.

(c) Chemical shift 1.20 ppm, the CH2 protons,  (CH3)2CHCH2CH3

This proton resonance is split into a 1:4:6:4:1 quintet by the CH proton and the right-hand CH3 group protons (n+1 = 5).

(d) Chemical shift 0.865 ppm, the right-hand CH3 protons,  (CH3)2CHCH2CH3

This proton 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 2-methylbutane

alkanes structure and naming (c) doc b Summary of the 1H NMR spectrum of 2-methylbutane

2-methylbutane’s proton NMR spectrum is a good example for teaching alkane proton environments, integration, and splitting.

 

Key Features of the ¹H NMR Spectrum of 2-Methylbutane

2-methylbutane (C5H12) is a branched alkane with four distinct proton environments.

Its spectrum shows only 4 alkyl signals, with chemical shifts in the 0.9–1.5 ppm range.

Four different proton chemical environments.

No deshielded protons (e.g. OH, aromatic, aldehyde) are present.

¹H NMR Chemical Shifts Table for the ¹H NMR Spectrum of 2-Methylbutane

Environment Hydrogen Type Chemical Shift (δ, ppm) Multiplicity Integration Origin
CH(CH3)2– Methyls (primary/sec) ~0.9, 0.87 ppm Doublet 6H Two equivalent terminal CH3 groups
–CH2– Methylene (secondary) ~1.3, 1.20 ppm Quintet 2H CH2 adjacent to CH3 and CH
–CH(CH3)– Methine (tertiary) ~1.5, 1.45 ppm Multiplet 1H Central CH bonded to CH2 and CH3
CH3–CH2– End methyl primary ~0.9, 0.87 ppm Triplet 3H CH3 bonded to CH2

Note: Exact chemical shifts may vary slightly depending on solvent and instrument, but these are typical values for non-polar alkanes.

Signal Origins & Splitting Patterns for the ¹H NMR Spectrum of 2-Methylbutane
  • Triplet (CH3–CH2–): Each CH3 sees 2 adjacent CH3 protons → n+1 = 3
  • Sextet (CH2–): Coupled to 5 protons (3 from CH2, 2 from CH) → complex splitting
  • Multiplet (CH): Coupled to CH2 and CH3 → overlapping signals
  • Doublet (CH3–CH): Coupled to 1 CH proton → n+1 = 2

Common Misconceptions about the ¹H NMR Spectrum of 2-Methylbutane
  • Assuming each CH3 gives a separate signal: In 2-methylbutane, two CH3 groups are equivalent.
  • Overlooking symmetry: Students may predict more signals than actually appear.
  • Misidentifying splitting patterns: Sextets and multiplets can be misread as overlapping signals.
  • Confusing integration with number of signals: Integration reflects number of protons, not number of environments.

Exam Revision Tips

Memory Aids
  • “Integration = proton count”: Use ratios to match structure.
  • “n+1 rule”: Neighbouring protons determine splitting.
  • “Symmetry simplifies”: Equivalent groups reduce signal count.

Technique Tips

  • Label all signals: Assign chemical shifts to environments.
  • Use integration first: Helps identify equivalent groups.
  • Sketch the molecule: Visualise proton environments and neighbours.

Typical Board-Specific Focus

  • Emphasis on interpreting spectra and assigning signals.
  • May require full analysis including splitting and integration.
  • Expect questions on structure elucidation and spectral prediction.

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-methylbutane.
Number of protons 1H causing splitting Splitting pattern produced from the n+1 rule 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
Comparing the infrared, mass, 1H NMR and 13C NMR spectra of the 3 alkane isomers of C5H12

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 pentane, 2-methylbutane and 2,2-dimethylpropane image sizes.
Comparing the infrared spectra of pentane, 2-methylbutane and 2,2-dimethylpropane

Pentane, 2-methylbutane and 2,2-dimethylpropane are structural isomers of molecular formula C5H12

Pentane, 2-methylbutane and 2,2-dimethylpropane exemplify infrared spectra of  the alkane homologous series CnH2n+2  hydrocarbon molecules, where n = 5

INFRARED SPECTRA (above): There are, as expected, differences in the fingerprint region at wavenumbers 1500 to 400 cm-1, but there is no specific infrared absorption band for a functional group. The infrared spectra of pentane and 2-methylbutane seem very similar, but that of 2,2-dimethylpropane seems much simpler.
Comparing the mass spectra of pentane, 2-methylbutane and 2,2-dimethylpropane

Pentane, 2-methylbutane and 2,2-dimethylpropane are structural isomers of molecular formula C5H12

Pentane, 2-methylbutane and 2,2-dimethylpropane exemplify the mass spectra of  the alkane series CnH2n+2  hydrocarbon molecules, where n = 5

MASS SPECTRA (above): All three hydrocarbons show some similarities in their mass spectra e.g. m/z ions 27 to 29 for [C2Hx]+ (x = 2 and 4). The molecular ion peaks will be the same for all three isomers (m/z 72), but it is very tiny for 2,2-dimethypropane. The pattern ratios for m/z 39 to 43 are similar for pentane and 2-methylbutane, but m/z 42 and 43 ions are almost absent from the 2,2-dimethylpropane spectrum. The base peak ion for pentane is m/z 43, but for 2-methylbutane and 2,2-dimethylpropane it is m/z 57.
Comparing the 1H proton NMR spectra of pentane, 2-methylbutane and 2,2-dimethylpropane

Pentane, 2-methylbutane and 2,2-dimethylpropane are structural isomers of molecular formula C5H12

Pentane, 2-methylbutane and 2,2-dimethylpropane exemplify the 1H proton NMR spectra of the alkane homologous series CnH2n+2  hydrocarbon molecules where, n = 5

1H NMR SPECTRA (above): The 1H NMR spectra of all three molecules give different proton ratios for the different 1H chemical environments i.e. pentane's proton ratio is 3:2:1 (from 6:4:2 H's in the molecule). 2-methylbutane's proton ratio is 6:1:2:3 and 2,2-dimethylpropane's doesn't have a proton ratio, all hydrogen atoms are equivalent. This means all three isomeric C5H12 hydrocarbons can be distinguished from their 1H NMR spectra.
Comparing the carbon-13 NMR spectra of pentane, 2-methylbutane and 2,2-dimethylpropane

Pentane, 2-methylbutane and 2,2-dimethylpropane are structural isomers of molecular formula C5H12

Pentane, 2-methylbutane and 2,2-dimethylpropane exemplify the carbon-13 NMR spectra of members of  the alkane homologous series CnH2n+2  hydrocarbon molecules, where n = 5

13C NMR SPECTRA (above): The 13C NMR spectra of the three molecules show different numbers of carbon-13 chemical environments i.e different numbers of 13C NMR resonance lines. So, pentane gives three 13C chemical shifts, 2-methylbutane four and 2,2-dimethylpropane two. This means all three isomeric C5H12 hydrocarbons can be distinguished from their 13C NMR spectra.

Key words & phrases: isopentane methylbutane Interpreting the proton H-1 NMR spectra of 2-methylbutane, low resolution & high resolution proton nmr spectra of 2-methylbutane, H-1 nmr spectrum of 2-methylbutane, understanding the hydrogen-1 nmr spectrum of 2-methylbutane, explaining the line splitting patterns in the high resolution H-1 nmr spectra of 2-methylbutane, revising the H-1 nmr spectrum of 2-methylbutane, proton nmr of 2-methylbutane, ppm chemical shifts of the H-1 nmr spectrum of 2-methylbutane, 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-methylbutane, how to work out the number of chemically different protons in the structure of the 2-methylbutane organic molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR spectrum of 2-methylbutane using the n+1 rule to explain the spin - spin coupling splitting in the proton nmr spectrum of 2-methylbutane deducing the nature of the protons from the chemical shifts ppm in the H-1 nmr spectrum of 2-methylbutane examining the 1H nmr spectrum of  2-methylbutane analysing the 1-H nmr spectrum of 2-methylbutane how do you sketch and interpret the H-1 NMR spectrum of 2-methylbutane isopentane methylbutane Molecular structure diagram of the proton NMR diagram for the 1H NMR spectrum of 2-methylbutane. The proton ratio in the 1H NMR spectrum of 2-methylbutane. Deducing the number of different chemical environments of the protons in the 2-methylbutane molecule from the 1H chemical shifts in the hydrogen-1 NMR spectrum of 2-methylbutane. Analysing the high resolution 1H NMR spectrum of 2-methylbutane. Analysing the low resolution 1H NMR spectrum of 2-methylbutane. You may need to know the relative molecular mass of 2-methylbutane to deduce the molecular formula from the proton ratio of the 1H NMR spectrum of 2-methylbutane. Revision notes on the proton NMR spectrum of 2-methylbutane. Matching and deducing the structure of the 2-methylbutane molecule from its hydrogen-1 NMR spectrum. Proton NMR spectroscopy of aliphatic alkanes, 1H NMR spectra of 2-methylbutane, an isomer of molecular formula C5H12 How do you interpret the H-1 NMR spectrum of 2-methylbutane How to interpret the H-1 NMR spectrum of 2-methylbutane Explanatory diagram of the chemical shifts of the 1H H-1 proton NMR spectrum of the 2-methylbutane molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the proton NMR spectrum of 2-methylbutane. How to explain the H-1 NMR spectrum of 2-methylbutane. The chemical shifts and  integrated values of the proton ratios in the 1-H NMR spectrum of the 2-methylbutane molecule. How to work out the molecular structure of the 2-methylbutane molecule from its proton NMR spectrum. The uses and distinctive features of the proton NMR spectrum of the 2-methylbutane molecule explained. What does the H-1 proton NMR spectrum chemical shifts tell us about the structure and properties of the 2-methylbutane molecule? explaining the spin-spin proton coupling effects in the 1H NMR spectrum of 2-methylbutane. 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-methylbutane

Links associated with 2-methylbutane

The chemistry of ALKANES and the petrochemical industry

The infrared spectrum for 2-methylbutane

The mass spectrum for 2-methylbutane

The C-13 NMR spectrum for 2-methylbutane

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

Website content © Dr Phil Brown 2000+. All copyrights reserved on revision notes, images, quizzes, worksheets etc. Copying of Doc Brown's pre-university advanced level chemistry website material is NOT permitted. Exam revision summaries & references to science course specifications are unofficial. These organic chemistry revision notes on spectroscopy are suitable for use of pre-university students studying AQA advanced level chemistry, Edexcel advanced level chemistry, OCR advanced level chemistry, IB advanced level chemistry, WJEC (Eduqas) advanced level chemistry, CIE advanced level chemistry, US grade 11-12 AP honors chemistry courses and they will also prove useful to 1st year undergraduate students of chemistry.

Website content © Dr Phil Brown 2000+. All copyrights reserved on revision notes, images, quizzes, worksheets etc. Copying of website material is NOT permitted. Exam revision summaries & references to A level chemistry course specifications are unofficial. Website content © Dr Phil Brown 2000+. All copyrights reserved on these organic chemistry exam revision notes on 1H NMR spectrum of 2-methylbutane, these A level chemistry revision notes are suitable for use of pre-university students studying AQA advanced level organic chemistry revision notes on 1H NMR spectrum of 2-methylbutane, Edexcel advanced level organic chemistry revision notes on 1H NMR spectrum of 2-methylbutane, OCR advanced level organic chemistry revision notes on 1H NMR spectrum of 2-methylbutane, IB advanced level organic chemistry revision notes on 1H NMR spectrum of 2-methylbutane, WJEC (Eduqas) advanced level organic chemistry revision notes on 1H NMR spectrum of 2-methylbutane, CIE Cambridge advanced level organic chemistry revision notes on 1H NMR spectrum of 2-methylbutane, CCEA advanced level organic chemistry revision notes on 1H NMR spectrum of 2-methylbutane, and useful for US grade 11 grade 12 AP honors organic chemistry courses involving 1H NMR spectrum of 2-methylbutane Explaining the importance of 1H NMR spectrum of 2-methylbutane in organic chemistry, What you need to know about 1H NMR spectrum of 2-methylbutane for organic chemistry, Explaining the use of 1H NMR spectrum of 2-methylbutane knowledge in organic chemistry, Examples of 1H NMR spectrum of 2-methylbutane explained when studying organic chemistry, What is the significance of 1H NMR spectrum of 2-methylbutane in organic chemistry, What is the use of 1H NMR spectrum of 2-methylbutane in organic chemistry  Describing and explaining the theory of 1H NMR spectrum of 2-methylbutane when studying organic chemistry, exam revision notes for 1H NMR spectrum of 2-methylbutane in exams, online help for 1H NMR spectrum of 2-methylbutane, revision notes for 1H NMR spectrum of 2-methylbutane, what do I need to learn for 1H NMR spectrum of 2-methylbutane in exams? revision summary for 1H NMR spectrum of 2-methylbutane, help in teaching 1H NMR spectrum of 2-methylbutane, learning notes for 1H NMR spectrum of 2-methylbutane, help to pass the 1H NMR spectrum of 2-methylbutane exam, how to prepare for examination questions on 1H NMR spectrum of 2-methylbutane?

TOP OF PAGE