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Structure determination
MASS SPECTROMETRY

Mass spectrometry is used to measure relative atomic masses of isotopes and relative
molecular masses
Vaporisation: sample turned into gas
Ionisation: gas particles bombarded with high-energy electrons- electrons knocked off ­
leaving positive ions
Acceleration: positive ion accelerated by an electric field
Deflection: ions deflected by…

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Typically fragment at the carbonyl group to give an alkyl radical and a stable RCO+ cation
(acylium ion)- stable because the RCO+ ion has a positive charge localised on the carbon
atom, the carbonyl group is polarised Cdelta+=Odelta- because oxygen is more electronegative
than carbon:

RCOR+ RCO+ +R

The abundant…

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INFRA-RED SPECTRA OF COMPOUNDS CONTAINING THE C=O GROUP.

Aldehydes, ketones, carboxylic acids, and esters are all carbonyl compounds
It has a stretching frequency of 1700 cm-1

Infra-red spectra of ketones and aldehydes

Peak produced by ketones and aldehydes is usually strong and sharp
Aldehydes: between 1740 and 1720 cm-1
Ketones:…

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