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

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

Advanced Organic Chemistry: Mass spectrum of propan-2-amine

Interpreting the mass spectrum of propan-2-amine (2-aminopropane, 2-propanamine, 2-propylamine, isopropylamine)

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 mass spectra of propan-2-amine (2-aminopropane)

mass spectrum of propan-2-amine (2-aminopropane) C3H9N (CH3)2CHNH2 fragmentation pattern of m/z m/e ions for analysis and identification of isopropylamine 2-propylamine 2-propanamine image diagram doc brown's advanced organic chemistry revision notes 

propan-2-amine, 2-aminopropane, 2-propylamine, 2-propanamine, isopropylamine, (c) doc b, (c) doc b

Interpreting the fragmentation pattern of the mass spectrum of propan-2-amine (2-aminopropane)

[M]+ is the molecular ion peak with an m/z of 59 corresponding to [C3H9N]+, the original propan-2-amine (2-aminopropane) molecule minus an electron, [(CH3)2CHNH2]+.

The tiny M+1 peak at m/z 60, corresponds to an ionised propan-2-amine (2-aminopropane) molecule with one 13C atom in it i.e. an ionised propan-2-amine (2-aminopropane) molecule of formula [13C12C2H9N]+

Carbon-13 only accounts for ~1% of all carbon atoms (12C ~99%), but the more carbon atoms in the molecule, the greater the probability of observing this 13C M+1 peak.

propan-2-amine (2-aminopropane) has 3 carbon atoms, so on average, ~1 in 33 molecules will contain a 13C atom.

The most abundant ion of the molecule under mass spectrometry investigation (propan-2-amine (2-aminopropane)) is usually given an arbitrary abundance value of 100, called the base ion peak, and all other abundances ('intensities') are measured against it.

Identifying the species giving the most prominent peaks (apart from M) in the fragmentation pattern of propan-2-amine (2-aminopropane).

Unless otherwise indicated, assume the carbon atoms in propan-2-amine (2-aminopropane) are the 12C isotope.

Some of the possible positive ions, [molecular fragment]+, formed in the mass spectrometry of propan-2-amine (2-aminopropane).

m/z value of [fragment]+ 58 45 44 43 42 41 40
[molecular fragment]+ [C3H8N]+ [13C12CH6N]+ [C2H6N]+ [C2H5N]+ [C2H4N]+ [C2H3N]+ [C2H2N]+
m/z value of [fragment]+ 39 30 28 28 ? 27 27 18 ? 15
[molecular fragment]+ [?]+ [CH4N]+ [CH2N]+ [C2H4]+ [CHN]+ [C2H3]+ [?]+ [CH3]+

Analysing and explaining the principal ions in the fragmentation pattern of the mass spectrum of propan-2-amine (2-aminopropane)

Atomic masses: H = 1;  C = 12;  N = 14

Bond enthalpies kJ/mol: C-C = 348;  C-H = 412;  C-N = 305;  N-H = 391

Possible equations to explain the most abundant ion peaks of propan-2-amine (2-aminopropane) (tabulated above)

Formation of m/z 44 ion:

[(CH3)2CHNH2]+  ===>  [C2H6N]+  +  CH3

C-C bond scission, loss of methyl group from parent molecular ion, 59 - 15 = 44.

The m/z 44 ion is the base peak ion, the most abundant and 'stable' ion fragment.

This is a characteristic ion formed in the mass spectrum of aliphatic amines.

Further hydrogen atom losses will give the 43, 42, 41, 40 and 39 ions.

Formation of m/z 15 ion:

[(CH3)2CHNH2]+  ===>  [CH3]+  +  C2H6N

Loss of methyl group from parent molecular ion, but carries the positive charge, mass change 59 - 44 = 15.

The positive methyl ion could be formed from other fragments too.


Key words & phrases: isomer of C3H9N (CH3)2CHNH2 image diagram on how to interpret and explain the mass spectrum of propan-2-amine (2-aminopropane) m/z m/e base peaks, image and diagram of the mass spectrum of propan-2-amine (2-aminopropane), details of the mass spectroscopy of propan-2-amine (2-aminopropane),  low and high resolution mass spectrum of propan-2-amine (2-aminopropane), prominent m/z peaks in the mass spectrum of propan-2-amine (2-aminopropane), comparative mass spectra of propan-2-amine (2-aminopropane), the molecular ion peak in the mass spectrum of propan-2-amine (2-aminopropane), analysing and understanding the fragmentation pattern of the mass spectrum of propan-2-amine (2-aminopropane), characteristic pattern of peaks in the mass spectrum of propan-2-amine (2-aminopropane), relative abundance of mass ion peaks in the mass spectrum of propan-2-amine (2-aminopropane), revising the mass spectrum of propan-2-amine (2-aminopropane), revision of mass spectroscopy of propan-2-amine (2-aminopropane), most abundant ions in the mass spectrum of propan-2-amine (2-aminopropane), how to construct the mass spectrum diagram for abundance of fragmentation ions in the mass spectrum of propan-2-amine (2-aminopropane), how to analyse the mass spectrum of propan-2-amine (2-aminopropane), how to describe explain the formation of fragmented ions in the mass spectra of propan-2-amine (2-aminopropane) equations for explaining the formation of the positive ions in the fragmentation of the ionised molecule of propan-2-amine (2-aminopropane) recognising the base ion peak of propan-2-amine (2-aminopropane) interpreting interpretation the mass spectrum of propan-2-amine (2-aminopropane) formula old names functional group primary aliphatic amine isopropylamine 2-propylamine 2-propanamine


Links associated with propan-2-amine (2-aminopropane)

The chemistry of ORGANIC NITROGEN COMPOUNDS revision notes INDEX

Mass 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