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 2,4-dimethylpentane

The mass spectrum of 2,4-dimethylpentane

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 2,4-dimethylpentane

C7H16 mass spectrum of 2,4-dimethylpentane fragmentation pattern of m/z m/e ions for analysis and identification of 2,4-dimethylpentane image diagram doc brown's advanced organic chemistry revision notes 

2,4-dimethylpentane 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 2,4-dimethylpentane

[M]+ is the molecular ion peak (M) with an m/z of 100 corresponding to [C7H16]+, the original 2,4-dimethylpentane molecule minus an electron, [(CH3)2CHCH2CH(CH3)2]+.

You might see a tiny M+1 peak at m/z 101, corresponding to an ionised 2,4-dimethylpentane molecule with one 13C atom in it i.e. an ionised 2,4-dimethylpentane 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.

Identifying the species giving the most prominent peaks (apart from M) in the fragmentation pattern of 2,4-dimethylpentane.

m/z value of [fragment]+ 85 69 58 57 56 55
[molecular fragment]+ [C6H13]+ [C5H9]+ [C5H8]+ [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 2,4-dimethylpentane

Equations to explain the most abundant ion peaks of 2,4-dimethylpentane

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

Formation of m/z 85 ion:

[(CH3)2CHCH2CH(CH3)2]+  ===>  [C6H13]+  +  CH3

Here an end methyl group is broken off, mass loss = 100 - 15 = 81.

Formation of m/z 57 ion:

[(CH3)2CHCH2CH(CH3)2]+  ===>  [CH3CHCH2CH3]+  +  CH3CHCH3

Loss of a CH3CHCH3 group, mass loss = 100 - 43 = 57.

The m/z 57 ion intensity is nearly as high as the base peak ion of m/z 43.

It can also be formed by elimination of ethene from the m/z 85 ion (85 - 28 = 57).

[C6H13]+  ===>  [C4H9]+  +  C2H4

Formation of m/z 43 ion:

[(CH3)2CHCH2CH(CH3)2]+  ===>  [CH3CHCH3]+  +  C4H9

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

Formation of m/z 29 ion:

[(CH3)2CHCH2CH(CH3)2]]+  ===>  [CH2CH3]+  +  C5H11

Mass loss = 100 - 71 = 29.


Key words & phrases: C7H16 image diagram on how to interpret and explain the mass spectrum of 2,4-dimethylpentane m/z m/e base peaks, image and diagram of the mass spectrum of 2,4-dimethylpentane, details of the mass spectroscopy of 2,4-dimethylpentane,  low and high resolution mass spectrum of 2,4-dimethylpentane, prominent m/z peaks in the mass spectrum of 2,4-dimethylpentane, comparative mass spectra of 2,4-dimethylpentane, the molecular ion peak in the mass spectrum of 2,4-dimethylpentane, analysing and understanding the fragmentation pattern of the mass spectrum of 2,4-dimethylpentane, characteristic pattern of peaks in the mass spectrum of 2,4-dimethylpentane, relative abundance of mass ion peaks in the mass spectrum of 2,4-dimethylpentane, revising the mass spectrum of 2,4-dimethylpentane, revision of mass spectroscopy of 2,4-dimethylpentane, most abundant ions in the mass spectrum of 2,4-dimethylpentane, how to construct the mass spectrum diagram for abundance of fragmentation ions in the mass spectrum of 2,4-dimethylpentane, how to analyse the mass spectrum of 2,4-dimethylpentane, how to describe explain the formation of fragmented ions in the mass spectra of 2,4-dimethylpentane equations for explaining the formation of the positive ions in the fragmentation of the ionised molecule of 2,4-dimethylpentane recognising the base ion peak of 2,4-dimethylpentane interpreting interpretation the mass spectrum of 2,4-dimethylpentane (CH3)2CHCH2CH(CH3)2 


Links associated with 2,4-dimethylpentane

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?,