C7H16 2,2,3-trimethylbutane low high resolution 1H proton nmr spectrum of analysis interpretation of chemical shifts ppm spin spin line splitting H-1 2,2,3-trimethylbutane 1-H nmr doc brown's advanced organic chemistry revision notes

Advanced Organic Chemistry: 1H NMR spectrum of 2,2,3-trimethylbutane (CH₃)₂CHC(CH₃)₃

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Interpreting the ¹H NMR spectrum of 2,2,3-trimethylbutane

[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 & AP honors chemistry courses: Molecular spectroscopy - analysing 1H NMR spectrum of 2,2,3-trimethylbutane [spectra updated Mar 19th 2026 *]

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H-1 proton NMR spectroscopy - spectra index

Introductory note on the 1H NMR spectra of 2,2,3-trimethylbutane

Students and teachers please note my explanation of the proton NMR spectrum of 2,2,3-triimethylbutane is designed for advanced, but pre-university, chemistry courses.

The chemical shift δ splitting pattern effects for 2,2,3-triimethylbutane 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 2,2,3-triimethylbutane 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 2,2,3-triimethylbutane molecule.

The most common solvent used for investigating the 1H NMR spectrum of compounds like 2,2,3-triimethylbutane, is CDCl₃ and other deuterated solvents to avoid confusion with a ¹H NMR signal, ²D (²H) has a different NMR chemical shift.

C7H16 low and high resolution 1H proton nmr spectrum of 2,2,3-trimethylbutane analysis interpretation of chemical shifts ppm spin spin line splitting diagram H1 H-1 nmr for 2,2,3-trimethylbutane 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 - 2,2,3-trimethylbutane here.

The chemical shifts quoted in ppm on the diagram of the H-1 NMR spectrum of 2,2,3-trimethylbutane 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 2,2,3-trimethylbutane molecule.

2,2,3-trimethylbutane C₇H₁₆

For more see The molecular structure, classification and naming of alkanes

Interpreting the H-1 NMR spectrum of 2,2,3-trimethylbutane

For relatively simple molecules, the low resolution H-1 NMR spectrum of 2,2,3-trimethylbutane is a good starting point (low resolution diagram above).

Theoretically, the hydrogen atoms (protons) of 2,2,3-trimethylbutane should occupy 3 different chemical environments so that the high resolution NMR spectra should show 3 principal peaks of different H-1 NMR chemical shifts (diagram above for 2,2,3-trimethylbutane).

The low resolution spectrum only shows two peaks in the proton ration 15:1

(CH₃)₃CCH(CH₃)₂

Note the proton ratio 9:1:6 of the 3 colours of the protons in the 3 chemically different environments

Chemical shifts (a) to (c) on the H-1 NMR spectrum diagram for 2,2,3-trimethylbutane.

Although there are 16 hydrogen atoms in the molecule, there are only 3 possible different chemical environments for the hydrogen atoms in 2,2,3-trimethylbutane

The integrated signal proton ratio 9:1:6 observed in the very high resolution H-1 NMR spectrum, corresponds with the structural formula of 2,2,3-trimethylbutane.

The high resolution 1H NMR spectrum of 2,2,3-trimethylbutane

The ppm quoted on the diagram represent the peak of resonance intensity for a particular proton group in the molecule of 2,2,3-trimethylbutane - 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 2,2,3-trimethylbutane below.

So, using the chemical shifts and applying the n+1 rule to 2,2,3-trimethylbutane and make some predictions using some colour coding! (In problem solving you work the other way round!)

(a) ¹H Chemical shift 0.834 ppm, 3 x methyl protons: (CH₃)₃CCH(CH₃)₂

This proton resonance is not split because there are no protons on the adjacent carbon atom, so this produces a singlet resonance.

All nine protons are equivalent to each other, in the same chemical environment, giving the same 1-H NMR chemical shift.

(b) ¹H Chemical shift 0.830 ppm, 2 x methyl protons: (CH₃)₃CCH(CH₃)₂

This resonance is split into a doublet by the CH proton (n+1 = 2)

All six protons are equivalent to each other, in the same chemical environment, giving the same 1-H NMR chemical shift.

Evidence for the presence of a CH group in the molecule of 2,2,3-trimethylbutane

You need very high resolution to sort out 1H NMR resonances (a) and (b).

(c) ¹H Chemical shift 1.38 ppm, CH proton : (CH₃)₃CCH(CH₃)₂

This resonance is split into a septet by the 2 x CH₃ protons (n+1 = 7)

Evidence for the presence of a CH₃-C-CH₃ grouping in the molecule of 2,2,3-trimethylbutane

Key points about the ¹H NMR spectrum of 2,2,3-trimethylbutane and a practice question

Molecular Overview: 2,2,3-trimethylbutane

Molecular formula: C₇H₁₆
Structure: Highly branched alkane with three methyl groups on C2, two methyl groups on C3, and one methine proton on C3
Symmetry: Partial symmetry — leads to three distinct proton environments

Key ¹H NMR Spectrum Features for 2,2,3-trimethylbutane

Chemical Shift (δ, ppm)	Proton Type	Environment	Integration	Multiplicity	Notes
~0.88, 0.834 ppm	CH₃ (3× methyl)	Attached to C2 (tertiary carbon)	9H	Singlet	Equivalent due to symmetry
~0.93, 0.830 ppm	CH3 (2× methyl)	Attached to C3 (secondary carbon)	6H	Singlet	Slightly different environment
~1.50, 1.38 ppm	CH (methine)	Central CH at C3	1H	Singlet	No neighboring protons

Total protons = 9 + 6 + 1 = 16
Three signals due to distinct environments: tertiary methyls, secondary methyls, and one methine proton

Source: https://sdbs.db.aist.go.jp/ diagram ¹H δ ppm spectral database of organic compounds

Common Misconceptions

Misconception	Clarification
"All methyl groups give the same signal"	Only if they’re in identical environments — here, C2 and C3 methyls differ
"Symmetrical molecules give one peak"	Partial symmetry can still yield multiple environments
"Multiplicity always means splitting"	Singlets occur when protons have no neighbours (n = 0)
"Integration is always 1:1"	Integration reflects number of protons in each environment — not equal unless structure dictates it

Exam Revision Tips

Count environments, not atoms: Use symmetry and bonding to identify equivalent protons.
Use integration ratios: 9:6:1 is diagnostic for this molecule.
Multiplicity = n+1 rule: Only applies when neighboring protons exist — here, all signals are singlets.
Chemical shift clues: Alkyl protons appear between ~0.8–1.5 ppm.
Compare with isomers: Isomers like 3-methylhexane show more signals and splitting.

Tips for spotting equivalent methyl group protons in ¹H NMR

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 can lead to equivalence.
Use integration clues: If two methyl groups give a single peak with integration of 6H (3 gives 9H), that's a strong hint they are equivalent.
Compare with isomers: Try contrasting 2,2,3-trimethylbutane with 2,2-dimethylpentane with 3-methylhexane, where methyl proton environments differ more clearly.

Counting methyls as separate signals: Leads to overestimating the number of peaks in ¹H 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.

Practice Question

Q: The ¹H NMR spectrum of a hydrocarbon shows three singlets: one at δ = 0.88 ppm integrating to 9 protons, one at δ = 0.93 ppm integrating to 6 protons, and one at δ = 1.50 ppm integrating to 1 proton.
Which of the following is the most likely identity of the compound?

Heptane
2,2,3-Trimethylbutane
3-Methylhexane
Cycloheptane

Model Answer

Correct answer: B. 2,2,3-Trimethylbutane

Justification:

Three singlets → indicates no splitting and distinct environments
Integration 9:6:1 → matches three methyls on C2, two methyls on C3, and one methine proton
Chemical shifts → consistent with alkyl protons
Other options would show more signals and splitting due to less symmetry and more varied environments

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).

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

Comparing the 1H NMR and 13C NMR spectra of the nine alkane structural isomers of C₇H₁₆ You can distinguish all 9 isomers from a data combination of their number of ¹H NMR chemical shifts, and their resulting integrated ¹H proton ratios, plus, their number of ¹³C chemical shifts.
Name of the alkane structural isomer of molecular formula C₇H₁₆	Abbreviated structural formulae of the nine isomers of molecular formula C₇H₁₆ (interpretation complications with 3-methylhexane and 2,3-dimethylpentane because they exhibit R/S isomerism due to a chiral carbon)	Skeletal formula of the nine alkane isomers of molecular formula C₇H₁₆	Number of ¹H NMR chemical shifts (δ) and proton ratio (links to spectrum)	Number of ¹³C chemical shifts (δ) (links to spectrum)
heptane			4 δ: proton ratio: 3:2:2:1 (6:4:4:2 in the molecule)	4 δ shifts
2-methylhexane			6 δ: proton ratio : 6:3:2:2:2:1	6 δ shifts
3-methylhexane			7 δ: proton ratio: 3:3:3:2:2:2:1 (simplification) !	7 δ shifts
3-ethylpentane			3 δ: proton ratio: 9:6:1	3 δ shifts
2,2-dimethylpentane			4 δ: proton ratio: 9:3:2:2	5 δ shifts
2,3-dimethylpentane			6 δ: proton ratio: 6:3:3:2:1:1 (simplification) !	6 δ shifts (simplification) !!!
2,4-dimethylpentane			3 δ: proton ratio: 12:2:2	3 δ shifts
3,3-dimethylpentane			3 δ: proton ratio: 3:3:2 (6:4:4 in the molecule)	4 δ shifts
2,2,3-trimethylbutane			3 δ: proton ratio: 9:6:1	4 δ shifts

Key words & phrases: C7H16 Interpreting the proton H-1 NMR spectra of 2,2,3-trimethylbutane, low resolution & high resolution proton nmr spectra of 2,2,3-trimethylbutane, H-1 nmr spectrum of 2,2,3-trimethylbutane, understanding the hydrogen-1 nmr spectrum of 2,2,3-trimethylbutane, explaining the line splitting patterns in the high resolution H-1 nmr spectra of 2,2,3-trimethylbutane, revising the H-1 nmr spectrum of 2,2,3-trimethylbutane, proton nmr of 2,2,3-trimethylbutane, ppm chemical shifts of the H-1 nmr spectrum of 2,2,3-trimethylbutane, 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 2,2,3-trimethylbutane, how to work out the number of chemically different protons in the structure of the 2,2,3-trimethylbutane organic molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR spectrum of 2,2,3-trimethylbutane using the n+1 rule to explain the spin - spin coupling ine splitting in the proton nmr spectrum of 2,2,3-trimethylbutane deducing the nature of the protons from the chemical shifts ppm in the H-1 nmr spectrum of 2,2,3-trimethylbutane examining the 1H nmr spectrum of 2,2,3-trimethylbutane analysing the 1-H nmr spectrum of 2,2,3-trimethylbutane how do you sketch and interpret the H-1 NMR spectrum of 2,2,3-trimethylbutane interpreting interpretation of the 1H proton NMR spectrum of 2,2,3-trimethylbutane (CH3)3CCH(CH3)2 (H3C)3CCH(CH3)2 Molecular structure diagram of the proton NMR diagram for the 1H NMR spectrum of 2,2,3-trimethylbutane. The proton ratio in the 1H NMR spectrum of 2,2,3-trimethylbutane. Deducing the number of different chemical environments of the protons in the 2,2,3-trimethylbutane molecule from the 1H chemical shifts in the hydrogen-1 NMR spectrum of 2,2,3-trimethylbutane. Analysing the high resolution 1H NMR spectrum of 2,2,3-trimethylbutane. Analysing the low resolution 1H NMR spectrum of 2,2,3-trimethylbutane. You may need to know the relative molecular mass of 2,2,3-trimethylbutane to deduce the molecular formula from the proton ratio of the 1H NMR spectrum of 2,2,3-trimethylbutane. Revision notes on the proton NMR spectrum of 2,2,3-trimethylbutane. Matching and deducing the structure of the 2,2,3-trimethylbutane molecule from its hydrogen-1 NMR spectrum. Proton NMR spectroscopy of aliphatic alkanes, 1H NMR spectra of 2,2,3-trimethylbutane, a structural isomer of molecular formula C7H16 How do you interpret the H-1 NMR spectrum of 2,2,3-trimethylbutane How to interpret the H-1 NMR spectrum of 2,2,3-trimethylbutane Explanatory diagram of the chemical shifts of the 1H H-1 proton NMR spectrum of the 2,2,3-trimethylbutane molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the proton NMR spectrum of 2,2,3-trimethylbutane. How to explain the H-1 NMR spectrum of 2,2,3-trimethylbutane. The chemical shifts and integrated values of the proton ratios in the 1-H NMR spectrum of the 2,2,3-trimethylbutane molecule. How to work out the molecular structure of the 2,2,3-trimethylbutane molecule from its proton NMR spectrum. The uses and distinctive features of the proton NMR spectrum of the 2,2,3-trimethylbutane molecule explained. What does the H-1 proton NMR spectrum chemical shifts tell us about the structure and properties of the 2,2,3-trimethylbutane molecule? explaining the spin-spin proton coupling effects in the 1H NMR spectrum of 2,2,3-trimethylbutane. interpretation 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 2,2,3-trimethylbutane

Links associated with 2,2,3-trimethylbutane

The infrared spectrum of 2,2,3-trimethylbutane

The mass spectrum of 2,2,3-trimethylbutane

The C-13 NMR spectrum of 2,2,3-trimethylbutane

The chemistry of ALKANES revision notes INDEX

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

ALL SPECTROSCOPY INDEXES

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Infrared spectra of the isomers of C₇H₁₆

The infrared spectrum of heptane

The infrared spectrum of 2-methylhexane

The infrared spectrum of 3-methylhexane

The infrared spectrum of 3-ethylpentane

The infrared spectrum of 2,2-dimethylpentane

The infrared spectrum of 2,3-dimethylpentane

The infrared spectrum of 2,4-dimethylpentane

The infrared spectrum of 3,3-dimethylpentane

The infrared spectrum of 2,2,3-trimethylbutane

Mass spectra of the isomers of C₇H₁₆

The mass spectrum of heptane

The mass spectrum of 2-methylhexane

The mass spectrum of 3-methylhexane

The mass spectrum of 3-ethylpentane

The mass spectrum of 2,2-dimethylpentane

The mass spectrum of 2,3-dimethylpentane

The mass spectrum of 2,4-dimethylpentane

The mass spectrum of 3,3-dimethylpentane

The mass spectrum of 2,2,3-trimethylbutane

H-1 proton NMR spectra of ALKANES

1H NMR spectra of the isomers of C₇H₁₆

The H-1 NMR spectrum of heptane

The H-1 NMR spectrum of 2-methylhexane

The H-1 NMR spectrum of 3-methylhexane

The H-1 NMR spectrum of 3-ethylpentane

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

The H-1 NMR spectrum of 2,3-dimethylpentane

The H-1 NMR spectrum of 2,4-dimethylpentane

The H-1 NMR spectrum of 3,3-dimethylpentane

The H-1 NMR spectrum of 2,2,3-trimethylbutane

C-13 carbon-13 NMR spectra of ALKANES

13C NMR spectra of the isomers of C₇H₁₆

The C-13 NMR spectrum of heptane

The C-13 NMR spectrum of 2-methylhexane

The C-13 NMR spectrum of 3-methylhexane

The C-13 NMR spectrum of 3-ethylpentane

The C-13 NMR spectrum of 2,2-dimethylpentane

The C-13 NMR spectrum of 2,3-dimethylpentane

The C-13 NMR spectrum of 2,4-dimethylpentane

The C-13 NMR spectrum of 3,3-dimethylpentane

The C-13 NMR spectrum of 2,2,3-trimethylbutane

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