CPL - Chalmers Publication Library
| Utbildning | Forskning | Styrkeområden | Om Chalmers | In English In English Ej inloggad.

A McLafferty - type rearrangement of a trimethylsilyl group in silylated hydroxy carbonyl compounds

Göran Petersson (Institutionen för teknisk kemi)
Organic Mass Spectrometry Vol. 6 (1972), p. 577-592.
[Artikel, refereegranskad vetenskaplig]

A McLafferty-type rearrangement of a trimethylsilyl group is demonstrated. Abundant rearrangement ions are formed for trimethylsilyl derivatives of alpha,beta-dihydroxy carbonyl compounds. Data are given for a large number of hydroxy acids and hydroxy ketones including aldonic acids, aldaric acids, acyclic ketoses and hydroxy keto acids. A few branched lactones are also shown to rearrange.

The positive charge and the unpaired electron are extensively delocalized in the odd-electron rearrangement ions. Those substituents at the alpha-carbon atom which offer a favourable delocalization promote the rearrangement. Spectra of specifically methylated species reveal that migration over larger than six-membered rings occurs to some extent. An observed dependence of abundance on configuration is associated with steric strains in the transition state.

The rearrangement ions are of great diagnostic value in structural analysis. They are relatively more abundant at low electron energies and give rise to the base peak at 20 eV for many compounds. Ions produced by the competing conventional McLafferty rearrangement are less abundant.

Nyckelord: mass spectrometry, Me3Si derivatives

This article deals with an unusual rearrangement which is central for stucture determinaton by mass spectrometry of Me3Si derivatives of sugar-related carbonyl compounds.

In the years 1970 to 1976 Göran Petersson was assistant professor and teacher of PhD courses in gas chromatography, mass spectrometry and carbohydrate chemistry. For training in interpretation of mass spectra an early textbook by Fred McLafferty was used.

Denna post skapades 2010-01-31. Senast ändrad 2011-06-20.
CPL Pubid: 111269


Läs direkt!

Lokal fulltext (fritt tillgänglig)

Institutioner (Chalmers)

Institutionen för teknisk kemi (1946-1998)



Chalmers infrastruktur

Relaterade publikationer

Denna publikation ingår i:

Gas chromatography - mass spectrometry of sugars and related hydroxy acids as trimethylsilyl derivatives