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 3-methylhexane

The mass spectrum of 3-methylhexane

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 3-methylhexane

C7H16 mass spectrum of 3-methylhexane fragmentation pattern of m/z m/e ions for analysis and identification of 3-methylhexane image diagram doc brown's advanced organic chemistry revision notes 

 3-methylhexane   C7H16   alkanes structure and naming (c) doc b

 alkanes structure and naming (c) doc b alkanes structure and naming (c) doc b

Interpreting the fragmentation pattern of the mass spectrum of 3-methylhexane

[M]+ is the molecular ion peak (M) with an m/z of 100 corresponding to [C7H16]+, the original 3-methylhexane molecule minus an electron, [CH3CH2CH(CH3)CH2CH2CH3]+.

The very tiny M+1 peak at m/z 105, corresponds to an ionised 3-methylhexane molecule with one 13C atom in it i.e. an ionised 3-methylhexane molecule of formula [13C12C6H16]+

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.

3-methylhexane has 7 carbon atoms, so, on average, ~1 in every 14 molecules will contain a 13C atom..

Identifying the species giving the most prominent peaks (apart from M) in the fragmentation pattern of 3-methylhexane.

m/z value of [fragment]+ 85 71 70 57 56 55
[molecular fragment]+ [C6H13]+ [C5H11]+ [C5H10]+ [C4H9]+ [C4H8]+ [C4H7]+
m/z value of [fragment]+ 43 42 41 39 29 27
[molecular fragment]+ [C3H7]+ [C3H6]+ [C3H5]+ [C3H3]+ [C2H5]+ [C2H3]+

Analysing and explaining the principal ions in the fragmentation pattern of the mass spectrum of 3-methylhexane

Equations to explain the most abundant ion peaks of 2-methylhexane

Formation of m/z 85 ion: [CH3CH2CH(CH3)CH2CH2CH3]+  ===>  [C6H13]+  +  CH3

Most fragmentation in alkanes arises from C-C bond scission (C-C bond weaker than C-H).

In this case and end methyl group is broken off, mass loss = 100 - 15 = 85.

Note in the equations below that both fragments are capable of being ionised, but only one at a time.

Many other fragments are formed by proton loss so get sequences like 71 => 70, 57 => 56 => 55, 43 => 42 => 41 => 40 => 39 and 29 => 28 => 27 etc.

Ethene is often eliminated to give a smaller fragment e.g. the m/z ion 85 gives the m/z ion 57

[C6H13]+  ===>  [C4H7]+  +  C2H4

Mass change 85 - 28 = 57.

Formation of m/z 71 ion: [CH3CH2CH(CH3)CH2CH2CH3]+  ===>  [C5H11]+  +  CH2CH3

Here an end ethyl group is broken off, mass loss = 100 - 29 = 71.

Formation of m/z 57 ion:

[CH3CH2CH(CH3)CH2CH2CH3]+  ===>  [CH3CH2CHCH3]+  +  CH2CH2CH3

Loss of propyl group, mass loss = 100 - 43 = 57

Formation of m/z 43 ion: [CH3CH2CH(CH3)CH2CH2CH3]+  ===>  [CH2CH2CH3]+  +  C4H9

Loss of a C4H9 group, mass loss = 100 - 57 = 43

The m/z 43 ion is the base peak ion, the most abundant and 'stable' ion fragment.

Loss of a C4H9 group, mass loss = 100 - 57 = 43

Formation of m/z 29 ion: [CH3CH2CH(CH3)CH2CH2CH3]+  ===>  [CH2CH3]+  +  C5H11

Here an end ethyl group is broken off, mass loss = 100 - 71 = 29.


Key words & phrases: C7H16 image diagram on how to interpret and explain the mass spectrum of 3-methylhexane m/z m/e base peaks, image and diagram of the mass spectrum of 3-methylhexane, details of the mass spectroscopy of 3-methylhexane,  low and high resolution mass spectrum of 3-methylhexane, prominent m/z peaks in the mass spectrum of 3-methylhexane, comparative mass spectra of 3-methylhexane, the molecular ion peak in the mass spectrum of 3-methylhexane, analysing and understanding the fragmentation pattern of the mass spectrum of 3-methylhexane, characteristic pattern of peaks in the mass spectrum of 3-methylhexane, relative abundance of mass ion peaks in the mass spectrum of 3-methylhexane, revising the mass spectrum of 3-methylhexane, revision of mass spectroscopy of 3-methylhexane, most abundant ions in the mass spectrum of 3-methylhexane, how to construct the mass spectrum diagram for abundance of fragmentation ions in the mass spectrum of 3-methylhexane, how to analyse the mass spectrum of 3-methylhexane, how to describe explain the formation of fragmented ions in the mass spectra of 3-methylhexane equations for explaining the formation of the positive ions in the fragmentation of the ionised molecule of 3-methylhexane recognising the base ion peak of 3-methylhexane interpreting interpretation the mass spectrum of 3-methylhexane  CH3CH2CH(CH3)CH2CH2CH3


Links associated with 3-methylhexane

The chemistry of ALKANES 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

latest video game release, latest pop music releases, download free music, latest film releases, latest high street fashion in clothes, fashionable trending in clothing, girls buy clothes, spend a lot of money on clothes, shoes, sweets and chocolates, magazines and make-up. Boys buy food and drink, computer games, DVDs and CDs, girls and boys spend a lot of money on credit for mobile phones, buses and trains to transport them going out. Girls spend a lot of money on clothes color colour preferences in clothes, cool sunglasses, boys  buy expensive things like designer sports clothes and trainers, teenagers save for holidays, clothes, mobile phones, birthday presents and electronic goods, teenage accessories, Favourite style of jeans. A typical girl’s shopping list includes mobile phone credit deals, fashionable quality cool airpods, air pods, fashionable clothes, the most popular favourite sneakers, fancy shoes, sweets, chocolates, magazines, lip moisturizer , lots on make-up, well being, teenage decor decorating their room, teenagers like LED string lantern lights, beauty products for teenagers, denim jackets, scrunchies coolness, fashionable back packs, typical boy’s shopping list includes mobile credit deals, eating out takeaway food and drinks, what teenagers like to buy in clothes, computer games, DVDs, CDs, what teenagers talk about, what teenagers worry about, what teenagers like to do for fun sports, what cool things do teenagers buy, resale websites like eBay Teenager education word cloud how do I apply to university to study biology?, what courses are available at university to study biology?, what grades do I need to get to university to study biology?, how do I apply to university to study chemistry?, what courses are available at university to study chemistry?, what grades do I need to get to university to study chemistry?, how do I apply to university to study physics?, what courses are available at university to study physics?, what grades do I need to get to university to study physics?, how do I apply to university to study biomedical sciences?, what courses are available at university to study biomedical sciences?, what grades do I need to get to university to study biomedical sciences, how do I apply to university to study medicine?, what courses are available at university to study medicine?, what grades do I need to get to university to study medicine?, how do I apply to university to study biochemistry?, what courses are available at university to study biochemistry?, what grades do I need to get to university to study biochemistry?, how do I apply to university to study mathematics?, what courses are available at university to study mathematics?, what grades do I need to get to university to study mathematics?, how do I apply to university to study chemical engineering?, what courses are available at university to study chemical engineering?, what grades do I need to get to university to study chemical engineering?, how do I apply to university to study civil engineering?, what courses are available at university to study civil engineering?, what grades do I need to get to university to study civil engineering?, how do I apply to university to study electrical engineering?, what courses are available at university to study electrical engineering?, what grades do I need to get to university to study electrical engineering?, how do I apply to university to study computer science?, what courses are available at university to study computer science?, what grades do I need to get to university to study computer science?,