Advanced Organic Chemistry: 1H NMR spectrum of cyclohexene

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

Interpreting the H-1 hydrogen-1 (proton) NMR spectrum of cyclohexene

Doc Brown's Chemistry Advanced Level Pre-University Chemistry Revision Study Notes for UK IB KS5 A/AS GCE advanced A level organic chemistry students US K12 grade 11 grade 12 organic chemistry courses involving molecular spectroscopy analysing H-1 NMR spectra of cyclohexene

Use your mobile phone in 'landscape' mode?

Links associated with cyclohexene

H-1 proton NMR spectroscopy - spectra index

1H proton nmr spectrum of cyclohexene low/high resolution diagrams C6H10 analysis interpretation of chemical shifts ppm spin spin line splitting diagram H1 H-1 nmr for cyclohexene 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 - cyclohexene here.

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

cyclohexene , alkenes structure and naming (c) doc b , alkenes structure and naming (c) doc b  ,  alkenes structure and naming (c) doc b

Interpreting the H-1 NMR spectrum of cyclohexene

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

The 10 hydrogen atoms (protons) of cyclohexene occupy 3 different proton chemical environments so that the low resolution NMR spectra should show 3 principal resonance peaks of different H-1 NMR chemical shifts (diagram above for cyclohexene).

Note the proton ratio 4:4 2 in the molecule of the 3 chemically different proton environments

Chemical shifts (a) to (c) on the H-1 NMR spectrum diagram for cyclohexene.

Although there are 10 hydrogen atoms in the molecule, the proton NMR spectrum shows there are only 3 possible different chemical environments for the hydrogen atoms in cyclohexene molecule - due to the symmetry of the hexagonal ring on either side of the C=C double bond.

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

The high resolution 1H NMR spectrum of cyclohexene

In terms of spin-spin coupling from the possible proton magnetic orientations, for cyclohexene I have only considered the interactions of non-equivalent protons on adjacent carbon atoms

e.g. -CH2-CH2, -CH-CH2-, protons etc.

The high resolution spectra of cyclohexene would show 3 groups of proton resonances and in the 4:4:2 (2:2:1) ratio expected from the structural formula of cyclohexene, but we can now consider the splitting of resonance lines from the spin-spin coupling in the molecule of cyclohexene.

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

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

1H NMR resonance (a) 1H Chemical shift δ 1.61 ppm:

The resonance for the 2 x CH2 protons furthest from the C=C bond.

This will be split into a triplet by the CH2 protons nearer the C=C bond (n+2 = 3).

This resonance is not split by the other CH2 protons furthest from the C=C bond because they are adjacent and equivalent to each other (the cyclohexene molecule is symmetrical about the -CH2-CH2- grouping furthest from the C=C bond)..

1H NMR resonance (b) 1H Chemical shift δ 1.98 ppm:

The resonance for the 2 x CH2 protons nearest to the C=C bond.

This resonance will be split into a quartet by the CH2 protons furthest from the C=C bond and the CH proton of the C=C bond (n+1 = 4).

This proton resonance is similar to the one above.

1H NMR resonance (c) 1H Chemical shift δ 5.66 ppm:

The resonance for the 2 x CH protons of the C=C bond.

Here the presence of the pi orbitals of the double bond results in a much greater 1H NMR chemical shift than is observed for the other four CH2 protons.

This resonance will be split into a triplet by the CH2 protons nearest the C=C bond (n+1 = 3).

This resonance is not split by the other CH proton of the C=C bond because they are adjacent and equivalent to each other (the cyclohexene molecule is symmetrical about the -CH=CH-).


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: isomer of molecular formula C6H10 Interpreting the proton H-1 NMR spectra of cyclohexene, low resolution & high resolution proton nmr spectra of cyclohexene, H-1 nmr spectrum of cyclohexene, understanding the hydrogen-1 nmr spectrum of cyclohexene, explaining the line splitting patterns from spin-spin coupling  in the high resolution H-1 nmr spectra of cyclohexene, revising the H-1 nmr spectrum of cyclohexene, proton nmr of cyclohexene, ppm chemical shifts of the H-1 nmr spectrum of cyclohexene, explaining and analyzing spin spin line splitting in the H-1 nmr spectrum, how to construct the diagram of the 1H nmr spectrum of cyclohexene, how to work out the number of chemically different protons in the structure of the cyclohexene organic molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR spectrum of cyclohexene using the n+1 rule to explain the spin - spin coupling ine splitting in the proton nmr spectrum of cyclohexene deducing the nature of the protons from the chemical shifts ppm in the H-1 nmr spectrum of cyclohexene examining the 1H nmr spectrum of cyclohexene analysing the 1H nmr spectrum of cyclohexene how do you sketch and interpret the H-1 NMR spectrum of cyclohexene interpreting interpretation of the 1H proton spin-spin coupling causing line splitting in the NMR spectrum of cyclohexene  assignment of chemical shifts in the proton 1H NMR spectrum of cyclohexene formula explaining spin-spin coupling for line splitting for cyclohexene alkene functional group How do you interpret the H-1 NMR spectrum of cyclohexene How to interpret the H-1 NMR spectrum of cyclohexene Explanatory diagram of the chemical shifts of the 1H H-1 proton NMR spectrum of the cyclohexene molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the proton NMR spectrum of cyclohexene. How to explain the H-1 NMR spectrum of cyclohexene. The chemical shifts and integrated values of the proton ratios in the 1-H NMR spectrum of the cyclohexene molecule. How to work out the molecular structure of the cyclohexene molecule from its proton NMR spectrum. The uses and distinctive features of the proton NMR spectrum of the cyclohexene molecule explained. What does the H-1 proton NMR spectrum chemical shifts tell us about the structure and properties of the cyclohexene molecule?


Links associated with cyclohexene

The infrared spectrum of cyclohexene

The mass spectrum of cyclohexene

The C-13 NMR spectrum of cyclohexene

The chemistry of ALKENES 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

All Advanced Organic Chemistry Notes

Use My Google search site box

Email doc b: chem55555@hotmail.com

TOP OF PAGE and indexes