HOME PAGE * KS3 SCIENCES * GCSE BIOLOGY CHEMISTRY PHYSICS * ADVANCED LEVEL CHEMISTRY

SPECTROSCOPY INDEXES  *  All Advanced Organic Chemistry Notes  *  [SEARCH BOX]

Advanced Organic Chemistry: 1H NMR spectrum of 1-chloro-2-methylpropane

The H-1 hydrogen-1 (proton) NMR spectrum of 1-chloro-2-methylpropane

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 1-chloro-2-methylpropane

C4H9Cl (CH3)2CH2Cl low and high resolution 1H proton nmr spectrum of 1-chloro-2-methylpropane analysis interpretation of chemical shifts ppm spin spin line splitting diagram H1 H-1 nmr for  isobutyl chloride 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 - 1-chloro-2-methylpropane here.

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

(c) doc b, (c) doc b, (c) doc b, (c) doc b, 1-chloro-2-methylpropane

Interpreting the H-1 NMR spectrum of 1-chloro-2-methylpropane

In terms of spin-spin coupling from the possible proton magnetic orientations, for 1-chloro-2-methylpropane I have only considered the interactions of non-equivalent protons on adjacent carbon atoms e.g. -CH2-CH.

For relatively simple molecules, the low resolution H-1 NMR spectrum of 1-chloro-2-methylpropane is a good starting point which will show 3 groups of protons in the ratio 6:1:3.

The hydrogen atoms (protons) of 1-chloro-2-methylpropane occupy 3 different chemical environments so that the low/high resolution NMR spectra should show 3 principal peaks of different H-1 NMR chemical shifts (diagram above for 1-chloro-2-methylpropane).

(CH3)2CHCH2Cl

Note the proton ratio 6:1:3 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 1-chloro-2-methylpropane.

Although there are 9 hydrogen atoms in the molecule, there are only 3 possible different chemical environments for the hydrogen atoms in 1-chloro-2-methylpropane molecule.

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

The high resolution 1H NMR spectrum of 1-chloro-2-methylpropane

All low and high resolution spectra of 1-chloro-2-methylpropane show ? groups of proton resonances and in the ? ratio expected from the formula of 1-chloro-2-methylpropane.

The ppm quoted on the diagram represent the peak of resonance intensity for a particular proton group in the molecule of 1-chloro-2-methylpropane - 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 1-chloro-2-methylpropane below.

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

(a) 1H Chemical shift 1.01 ppm, CH3 protons : (CH3)2CHCH2Cl

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

Evidence for the presence of a CH group in the molecule of 1-chloro-2-methylpropane

(b) 1H Chemical shift 1.95 ppm, CH proton : (CH3)2CHCH2Cl

This 1H resonance is split into a nonet by the adjacent 2 x CH3 and CH2 protons (n+1 = 9)

Evidence for the presence of a (CH3)2-C-CH2 group in the molecule of 1-chloro-2-methylpropane

(c) 1H Chemical shift 3.38 ppm, CH2 protons: (CH3)2CHCH2Cl

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

Evidence for the presence of a CH group in the molecule of 1-chloro-2-methylpropane

Note the decreasing effect on the 1H chemical shift as the proton is further from the more electronegative chlorine atom in 1-chloro-2-methylpropane.


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: C4H9Cl (CH3)2CH2Cl Interpreting the proton H-1 NMR spectra of 1-chloro-2-methylpropane, low resolution & high resolution proton nmr spectra of 1-chloro-2-methylpropane, H-1 nmr spectrum of 1-chloro-2-methylpropane, understanding the hydrogen-1 nmr spectrum of 1-chloro-2-methylpropane, explaining the line splitting patterns from spin-spin coupling  in the high resolution H-1 nmr spectra of 1-chloro-2-methylpropane, revising the H-1 nmr spectrum of 1-chloro-2-methylpropane, proton nmr of 1-chloro-2-methylpropane, ppm chemical shifts of the H-1 nmr spectrum of 1-chloro-2-methylpropane, 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 1-chloro-2-methylpropane, how to work out the number of chemically different protons in the structure of the 1-chloro-2-methylpropane organic molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR spectrum of 1-chloro-2-methylpropane using the n+1 rule to explain the spin - spin coupling ine splitting in the proton nmr spectrum of 1-chloro-2-methylpropane deducing the nature of the protons from the chemical shifts ppm in the H-1 nmr spectrum of 1-chloro-2-methylpropane examining the 1H nmr spectrum of  1-chloro-2-methylpropane analysing the 1-H nmr spectrum of 1-chloro-2-methylpropane how do you sketch and interpret the H-1 NMR spectrum of 1-chloro-2-methylpropane interpreting interpretation of the 1H proton spin-spin coupling causing line splitting in the NMR spectrum of 1-chloro-2-methylpropane  assignment of chemical shifts in the proton 1H NMR spectrum of 1-chloro-2-methylpropane formula explaining spin-spin coupling for line splitting of  isobutyl chloride


Links associated with 1-chloro-2-methylpropane

The chemistry of HALOGENOALKANES (haloalkanes) revision notes INDEX

H-1 proton NMR spectroscopy index

ALL SPECTROSCOPY INDEXES

All Advanced Organic Chemistry Notes

Use My Google search site box

Email doc b: chem55555@hotmail.com

TOP OF PAGE

 Doc Brown's Chemistry 

*

TOP OF PAGE