1H proton nmr spectrum of E-but-2-ene Z-but-2-ene low/high resolution analysis interpretation of chemical shifts ppm spin spin line splitting isomers E-2-butene Z-2-butene trans-but-2-ene cis-but-2-ene trans-2-butene cis-2-butene 1H nmr doc brown's advanced organic chemistry revision notes

Advanced pre-university Organic Chemistry: H-1 NMR spectra of E-but-2-ene AND Z-but-2-ene CH₃CH=CHCH₃

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Interpreting the H-1 (proton) NMR spectrum of E-but-2-ene and Z-but-2-ene (H1 NMR spectra of cis/trans stereoisomers of but-2-ene, 2-butene)

[Author © Dr WP Brown PhD: Doc Brown's Chemistry Advanced Level Pre-University Chemistry Revision Notes for UK IB KS5 A/AS GCE advanced A level organic chemistry students, IB chemistry US K12 grade 11 grade 12 organic chemistry courses on molecular spectroscopy analysing H-1 NMR spectra of E-but-2-ene & Z-but-2-ene [updated Mar 20th 2026 *]

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H-1 proton NMR spectroscopy - spectra index

Introductory note on the 1H NMR spectra of E/Z but-2-ene (cis/trans 2-butene isomers)

Students and teachers please note my explanation of the proton NMR spectrum of E/Z but-2-ene (cis/trans 2-butene isomers) is designed for advanced, but pre-university, chemistry courses.

The chemical shift δ splitting pattern effects for E/Z but-2-ene (cis/trans 2-butene isomers) 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 E/Z but-2-ene (cis/trans 2-butene isomers) 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 E/Z but-2-ene (cis/trans 2-butene isomers) molecule.

The most common solvent used for investigating the 1H NMR spectrum of compounds like E/Z but-2-ene (cis/trans 2-butene isomers), is CDCl₃ and other deuterated solvents to avoid confusion with a ¹H NMR signal, ²D (²H) has a different NMR chemical shift.

trans isomer 2-butene H-1 proton nmr spectrum of E-but-2-ene analysis interpretation of chemical shifts ppm spin spin line splitting diagram H1 1-H nmr doc brown's advanced organic chemistry revision notes

cis isomer 2-butene H-1 proton nmr spectrum of Z-but-2-ene analysis interpretation of chemical shifts ppm spin spin line splitting diagram H1 1-H nmr doc brown's advanced organic chemistry revision notes

(other names: E-2-butene & Z-2-butene, trans-but-2-ene & cis-but-2-ene, trans-2-butene & cis-2-butene)

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 - E-but-2-ene and Z-but-2-ene here.

The chemical shifts quoted in ppm on the diagram of the H-1 NMR spectrum of E-but-2-ene and Z-but-2-ene 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 E-but-2-ene and Z-but-2-ene molecule (trans-but-2-ene and cis-but-2-ene).

, structural formula of but-2-ene , but doesn't show the two different spatial arrangements possible due to a high energy barrier to rotation about the double bond, known as the E/Z stereoisomers (cis/trans)

Z-but-2-ene alkenes structure and naming (c) doc b or (Z-2-butene, cis-2-butene, cis-but-2-ene)

E-but-2-ene alkenes structure and naming (c) doc b or (E-2-butene, trans-2-butene, trans-but-2-ene)

The molecular structure and naming of alkenes

for more details and examples of E/Z isomerism see ...

STEREOISOMERISM general definition, E/Z (geometric/geometrical cis/trans) isomerism

Interpreting the H-1 NMR spectrum of E-but-2-ene and Z-but-2-ene

The hydrogen atoms (protons) of E-but-2-ene and Z-but-2-ene occupy 2 different chemical environments so that the low or high resolution NMR spectra should show 2 peaks of different H-1 NMR chemical shifts (diagrams above for E-but-2-ene and Z-but-2-ene).

CH₃CH=CHCH₃

Note the ratio 6:2 = 3:1 of the two colours of the protons in the two chemically different environments. The different stereoisomers of the same structural formula produce two slightly different chemical environments giving rise to two slight different NMR H-1 chemical shifts.

Although there are 6 hydrogen atoms in the molecule, there only 2 possible proton chemical environments for the hydrogen atoms in E-but-2-ene and Z-but-2-ene molecule.

The proton ratio 3:1 observed, corresponds with the structural formula of E-but-2-ene and Z-but-2-ene.

The high resolution H-1 NMR spectrum of E-but-2-ene and Z-but-2-ene

Both spectra are very similar.

All low and high resolution spectra of E-but-2-ene and Z-but-2-ene show 2 groups of protons and in the ratio expected from the formula of E-but-2-ene and Z-but-2-ene.

The ppm quoted on the diagram represent the peak of resonance intensity for a particular proton group in the molecule of E-but-2-ene and Z-but-2-ene - 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 E-but-2-ene and Z-but-2-ene below.

So, using the chemical shifts and applying the n+1 rule to E-but-2-ene and Z-but-2-ene

The CH₃ proton NMR chemical shift δ

For E-but-2-ene it is 1.58 ppm

For Z-but-2-ene it is 1.54 ppm

For both E/Z isomers of but-2-ene (2-butene) the CH₃ proton resonance is split into a 1:1 doublet by the CH proton (n+1 = 2).

Despite the difference in geometry, the chemical shift for the CH₃ protons is very similar, so the chemical environment of the CH₃ protons in but-2-ene must be very similar in both E/Z isomers.

Evidence for the presence of a CH group in the molecules of E-but-2-ene and Z-but-2-ene

The CH proton NMR chemical shift

For E-but-2-ene it is 5.58 ppm

For Z-but-2-ene it is 5.37 ppm

The CH proton resonance is split into a 1:3:3:1 quartet by the three CH₃ protons (n+1 = 4).

This is because the CH protons are adjacent and equivalent to each other (identical chemical environments), so theoretically, their proton fields cannot split each other.

Despite the difference in geometry, the chemical shift for the CH₃ protons is very similar, so the chemical environment of the CH proton in but-2-ene must be very similar in both isomers.

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 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

Key words & phrases: isomers of molecular formula C4H8 E-but-2-ene and Z-but-2-ene cis-2-butene trans-2-butene cis-but-2-ene trans-but-2-ene proton nmr spectrum Interpreting the proton H-1 NMR spectra of E-but-2-ene and Z-but-2-ene, low resolution & high resolution proton nmr spectra of E-but-2-ene and Z-but-2-ene, H-1 nmr spectrum of E-but-2-ene and Z-but-2-ene, understanding the hydrogen-1 nmr spectrum of E-but-2-ene and Z-but-2-ene, explaining the line splitting patterns in the high resolution H-1 nmr spectra of E-but-2-ene and Z-but-2-ene, revising the H-1 nmr spectrum of E-but-2-ene and Z-but-2-ene, proton nmr of E-but-2-ene and Z-but-2-ene, ppm chemical shifts of the H-1 nmr spectrum of E-but-2-ene and Z-but-2-ene, 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 E-but-2-ene and Z-but-2-ene, how to work out the number of chemically different protons in the structure of the E-but-2-ene and Z-but-2-ene organic molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR spectrum of E-but-2-ene and Z-but-2-ene using the n+1 rule to explain the spin - spin coupling ine splitting in the proton nmr spectrum of E-but-2-ene and Z-but-2-ene deducing the nature of the protons from the chemical shifts ppm in the H-1 nmr spectrum of E-but-2-ene and Z-but-2-ene examining the 1H nmr spectrum of E-but-2-ene and Z-but-2-ene analysing the 1-H nmr spectrum of E-but-2-ene and Z-but-2-ene how do you sketch and interpret the H-1 NMR spectrum of E-but-2-ene and Z-but-2-ene cis-2-butene trans-2-butene cis-but-2-ene trans-but-2-ene proton nmr spectrum interpretation Molecular structure diagram of the proton NMR diagram for the 1H NMR spectrum of E-but-2-ene Z-but-2-ene trans-2-butene cis-2-butene. The proton ratio in the 1H NMR spectrum of E-but-2-ene Z-but-2-ene trans-2-butene cis-2-butene. Deducing the number of different chemical environments of the protons in the E-but-2-ene Z-but-2-ene trans-2-butene cis-2-butene molecule from the 1H chemical shifts in the hydrogen-1 NMR spectrum of E-but-2-ene Z-but-2-ene trans-2-butene cis-2-butene. Analysing the high resolution 1H NMR spectrum of E-but-2-ene Z-but-2-ene trans-2-butene cis-2-butene. Analysing the low resolution 1H NMR spectrum of E-but-2-ene Z-but-2-ene trans-2-butene cis-2-butene. You may need to know the relative molecular mass of E-but-2-ene Z-but-2-ene trans-2-butene cis-2-butene to deduce the molecular formula from the proton ratio of the 1H NMR spectrum of E-but-2-ene Z-but-2-ene trans-2-butene cis-2-butene. Revision notes on the proton NMR spectrum of E-but-2-ene Z-but-2-ene trans-2-butene cis-2-butene. Matching and deducing the structure of the E-but-2-ene Z-but-2-ene trans-2-butene cis-2-butene molecule from its hydrogen-1 NMR spectrum. Proton NMR spectroscopy of alkenes, 1H NMR spectra of E-but-2-ene Z-but-2-ene trans-2-butene cis-2-butene, an isomer of molecular formula C4H8 How do you interpret the H-1 NMR spectrum of but-2-ene E/Z cis/trans geometric isomers How to interpret the H-1 NMR spectrum of but-2-ene E/Z cis/trans geometric isomers Explanatory diagram of the chemical shifts of the 1H H-1 proton NMR spectrum of the but-2-ene E/Z cis/trans geometric isomers molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the proton NMR spectrum of but-2-ene E/Z cis/trans geometric isomers. How to explain the H-1 NMR spectrum of but-2-ene E/Z cis/trans geometric isomers. The chemical shifts and integrated values of the proton ratios in the 1-H NMR spectrum of the but-2-ene E/Z cis/trans geometric isomers molecule. How to work out the molecular structure of the but-2-ene E/Z cis/trans geometric isomers molecule from its proton NMR spectrum. The uses and distinctive features of the proton NMR spectrum of the but-2-ene E/Z cis/trans geometric isomers molecule explained. What does the H-1 proton NMR spectrum chemical shifts tell us about the structure and properties of the but-2-ene E/Z cis/trans geometric isomers molecule? explaining the spin-spin proton coupling effects in the 1H NMR spectrum of but-2-ene E/Z cis/trans geometric isomers. 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 but-2-ene E/Z cis/trans geometric isomers proton H-1 NMR spectra of E-2-butene Z-2-butene trans-but-2-ene cis-but-2-ene trans-2-butene cis-2-butene

Links associated with E-but-2-ene and Z-but-2-ene

The chemistry of ALKENES revision notes INDEX

The infrared spectra of the E/Z isomers of but-2-ene (cis/trans isomers of 2-butene)

The mass spectra of the E/Z isomers of but-2-ene (cis/trans isomers of 2-butene)

The C-13 NMR spectra of the E/Z isomers of but-2-ene (cis/trans isomers of 2-butene)

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

ALL SPECTROSCOPY INDEXES

STEREOISOMERISM general definition, E/Z (geometric/geometrical cis/trans) isomerism
All Advanced Organic Chemistry Notes

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