Advanced Organic Chemistry: Carbon-13 NMR spectrum of 2,2-dimethylbutane (CH3)3CCH2CH3

HOME PAGE * SEARCH * GCSE Level Chemistry age ~14-16 * Advanced Level Chemistry age ~16-19

Interpreting 13C NMR spectrum of 2,2-dimethylbutane

[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 13C NMR spectrum of 2,2-dimethylbutane [updated October 28th 2025]

email doc brown  Re-edit  CH3CH2C(CH3)3

Links associated with 2,2-dimethylbutane

This is a BIG website, PLEASE take time to explore it

C-13 NMR spectroscopy - spectra index

See also comparing infrared, mass, 1H NMR & 13C NMR spectra of the structural alkane isomers of C6H14

Introductory note on the 13C NMR spectrum of 2,2-dimethylbutane

Students and teachers please note that my explanation of the carbon-13 NMR spectrum of 2,2-dimethylbutane is designed for advanced, but pre-university, chemistry courses.

The description does not involve the chemical shift δ spin-spin coupling effects for 2,2-dimethylbutane and the relative size of the carbon-13 NMR shifts does not give the ratio of the carbon atoms in the different non-equivalent chemical environments of the 2,2-dimethylbutane molecule.

The most common solvent used for investigating the C13 NMR spectrum of compounds like 2,2-dimethylbutane, is CDCl3 and other deuterated solvents.

C-13 nmr spectrum of 2,2-dimethylbutane analysis of chemical shifts ppm interpretation of C-13 chemical shifts ppm of 2,2-dimethylbutane C13 13-C nmr doc brown's advanced organic chemistry revision notes 

TMS is the acronym for tetramethylsilane, formula Si(CH3)4, whose 13C atoms are arbitrarily given a chemical shift of 0.0 ppm. This is the 'standard' in 13C NMR spectroscopy and all other 13C shifts, called chemical shifts, depend on the individual (electronic) chemical environment of the 13C atoms in an organic molecule - 2,2-dimethylbutane here.

 2,2-dimethylbutane, C6H14, 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, classification and naming of alkanes

Interpreting the C-13 NMR spectrum of 2,2-dimethylbutane

As you can see from the diagram above there are 4 different chemical shift lines in the C-13 NMR spectrum of 2,2-dimethylbutane indicating 4 different chemical environments of the six carbon atoms.

(CH3)3CCH2CH3 

(Note the 4 colours indicating the 4 different chemical environments of the carbon atoms in 2,2-dimethylbutane).

13C NMR chemical shifts (a) to (d) on the C-13 NMR spectrum diagram for 2,2-dimethylbutane

The carbon atoms of the three methyl groups of the C(CH3)3 grouping are all chemically equivalent to each other in the 2,2-dimethylbutane molecule i.e. they occupy the same chemical environment, and so give the same C-13 NMR chemical shift.

The carbon-13 NMR spectra a provides direct evidence of 4 different carbon atom environments in the 2,2-dimethylbutane molecule from 4 different chemical shifts (ppm).

alkanes structure and naming (c) doc bKey points about the 1H NMR spectrum of 2,2-dimethylbutane

Molecule: 2,2-Dimethylbutane
Formula: C6H14

Total number of carbon atoms: 6
Total number of distinct ¹³C environments: 4
Reason: Due to molecular symmetry, several carbon atoms are chemically equivalent.

Carbon environments and chemical shifts:

https://sdbs.db.aist.go.jp/ diagram 13C δ ppm spectral database of organic compounds

  1. Quaternary carbon (C bonded to four other carbon atoms)
    • Environment: Tertiary (central carbon)
    • Chemical shift: ~35–40 ppm
    • Unique carbon atom, 30.4 ppm
  2. Three equivalent methyl groups attached to the central carbon (CH3–C)
    • Environment: Primary (methyl)
    • Chemical shift: ~28–30 ppm
    • All three methyls are equivalent due to symmetry, 29.0 ppm
  3. One methylene group (CH2)
    • Environment: Secondary (CH2)
    • Chemical shift: ~22–25 ppm, 36.5 ppm
    • Unique environment
  4. One terminal methyl group (CH2–CH3)
    • Environment: Primary (methyl)
    • Chemical shift: ~10–15 ppm, 8.9 ppm
    • Distinct from the tertiary methyls

Common misconceptions:

  • Assuming all six carbon atoms give separate signals — incorrect due to equivalence.
  • Believing all methyl groups are equivalent — only the three on the central carbon are.
  • Thinking quaternary carbons don’t appear in ¹³C NMR — they do, though often weaker.
  • Confusing ¹³C NMR with ¹H NMR — ¹³C spectra typically show singlets (no splitting).

Exam tips (AQA, Edexcel, OCR, WJEC, CCEA, CIE, IB, US AP/Honors):

  • Always count distinct environments, not atoms.
  • Use symmetry to identify equivalent carbons.
  • Expect 4 signals for 2,2-dimethylbutane.
  • Know typical chemical shift ranges for alkyl carbons:
    • CH3: ~10–30 ppm
    • CH3: ~20–40 ppm
    • Quaternary C: ~30–50 ppm

Tips for spotting equivalent methyl group carbons in 13C NMR e.g. 4 methyl groups in 2,2-dimethylbutane

  • Check for identical attachments: If two or more methyl groups are bonded to the same carbon and that carbon is not chiral, they are usually equivalent.
  • Look for symmetry: Even partial symmetry (like in 2,2-dimethylbutane) can lead to equivalence.
  • Use integration clues: If two methyl groups give a single peak with integration of 6H, that’s a strong hint they’re equivalent.
  • Compare with isomers: Try contrasting with 2,2-dimethylbutane with 3-methylpentane, where methyl carbon environments differ more clearly.
  • Counting methyls as separate signals: Leads to overestimating the number of peaks in ¹³C NMR spectra.
  • Assuming all methyls are equivalent: Not true in asymmetric or chiral environments.
  • Ignoring branching effects: Branching can create or remove equivalence depending on the substitution pattern.
Comparing the infrared, mass, 1H NMR and 13C NMR spectra of the five structural alkane isomers of C6H14

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 hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane and 2,3-dimethylbutane image sizes.  These five molecules are structural isomers of saturated alkanes of molecular formula C6H14 and exemplify the infrared, mass, 1H NMR and 13C NMR spectra of lower aliphatic alkanes (non-cyclic alkanes).
Infrared spectra below.

INFRARED SPECTRA:

Apart from the significant differences in the fingerprint region at wavenumbers 1500 to 400 cm-1, there are no other great striking differences, but each could be identified from its infrared spectrum.

All the absorption bands are typical of molecules containing saturated alkyl structure and there are no characteristic infrared absorptions due to a specific functional group.
Infrared spectra above, mass spectra below.

MASS SPECTRA: Base ion peaks plus m/z comments.

Hexane: m/z 57, 42 and 56 prominent

2-methylpentane: m/z 43, 42 and 71 prominent

3-methylpentane: m/z 57, 41 and 56 prominent

2,2-dimethylbutane: m/z 43, 41, 57 and 71 prominent

2,3-dimethylbutane: m/z 43, 41, 42 and 71 prominent
Mass spectra above, 1H NMR spectra below.

1H NMR SPECTRA: They can all be distinguished by their different integrated proton ratios - need very high resolution.

Hexane: 3 1H δ shifts, H ratio 3:2:2 (6:4:4 in formula)

2-methylpentane: 5 1H δ shifts, H ratio 6:3:2:2:1

3-methylpentane: 4 1H δ shifts, H ratio 6:4:3:1

2,2-dimethylbutane: 3 1H δ shifts, H ratio 9:3:2

2,3-dimethylbutane: 2 1H δ shifts, H ratio 6:1 (12:2 in formula)
1H NMR spectra above, 13C NMR spectra below.

13C NMR SPECTRA: From the number of shifts, you can't distinguish (iii) and (iv) but you can distinguish them from (i), (ii) and (v). (i) Hexane: 3 13C δ shifts

(ii) 2-methylpentane: 5 13C δ shifts

(iii) 3-methylpentane: 4 13C δ shifts

(iv) 2,2-dimethylbutane: 4 13C δ shifts

(v) 2,3-dimethylbutane: 2 13C δ shifts
13C NMR spectra above.

Key words & phrases: Interpreting the C-13 NMR spectra of 2,2-dimethylbutane, C-13 nmr spectrum of 2,2-dimethylbutane, understanding the carbon-13 nmr spectrum of 2,2-dimethylbutane, explaining the line pattern in the high resolution C-13 nmr spectra of 2,2-dimethylbutane, revising the C-13 nmr spectrum of 2,2-dimethylbutane, ppm chemical shifts of the C-13 nmr spectrum of 2,2-dimethylbutane, how to construct the diagram of the C-13 nmr spectrum of 2,2-dimethylbutane, how to analyse the chemical shifts in the carbon-13 NMR spectrum of 2,2-dimethylbutane deducing the chemical environment of all the carbon atoms in 2,2-dimethylbutane examining the c13 nmr spectrum of  2,2-dimethylbutane analysing the 13-c nmr spectrum of 2,2-dimethylbutane how do you sketch and interpret the C-13 NMR spectrum of 2,2-dimethylbutane interpreting interpretation of the C-13 NMR spectrum of 2,2-dimethylbutane Molecular structure diagram of the carbon-13 NMR diagram for the 13C NMR spectrum of 2,2-dimethylbutane. Deducing the number of different chemical environments of the carbon atoms in the 2,2-dimethylbutane molecule from the 13C chemical shifts in the carbon-13 NMR spectrum of 2,2-dimethylbutane. Revision notes on the carbon-13 NMR spectrum of 2,2-dimethylbutane. Matching and deducing the structure of the 2,2-dimethylbutane molecule from its 13C NMR spectrum. Carbon-13 NMR spectroscopy of  aliphatic alkanes, 13C NMR spectra of 2,2-dimethylbutane, a structural isomer of molecular formula C6H14 How do you interpret the chemical shifts of the C-13 NMR spectrum of  2,2-dimethylbutane How to interpret the C-13 NMR spectrum of  2,2-dimethylbutane Explanatory diagram of the 13C C-13 carbon-13 NMR spectrum of the  number of different carbon atom environments in the  2,2-dimethylbutane molecule from its carbon-13 NMR spectrum to help work out the molecular structure of the  2,2-dimethylbutane molecule? The uses and distinctive features of the carbon-13 NMR spectrum of the  2,2-dimethylbutane molecule explained. What do the number and values of the chemical shifts from the c-13 carbon-13 NMR spectrum tell us about the  2,2-dimethylbutane molecule? explaining the decoupled carbon-13 NMR spectrum of  2,2-dimethylbutane  with a detailed interpretation diagram of all the C-13 chemical shifts and intensities

Links associated with 2,2-dimethylbutane

The chemistry of ALKANES revision notes INDEX

The infrared spectrum of 2,2-dimethylbutane

The mass spectrum of 2,2-dimethylbutane

The H-1 NMR spectrum of 2,2-dimethylbutane

C-13 NMR spectroscopy index

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.

TOP OF PAGE