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Site of gas-phase methylation of alkyl phenyl ketones

✍ Scribed by Mary Cheung; Alex G. Harrison

Publisher
John Wiley and Sons
Year
1995
Tongue
English
Weight
514 KB
Volume
30
Category
Article
ISSN
1076-5174

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✦ Synopsis

Abstract

The CH adducts of benzaldehyde, acetophenone, propiophenone and butyrophenone were prepared using CH~3~FCH~4~ and CH~3~ClCH~4~ mixtures under chemical ionization conditions and the unimolecular and collision‐induced fragmentation reactions of their adduct ions were studied. For comparison, the fragmentation reactions of the protonated p‐methylphenyl alkyl ketones were studied as models of the ring‐methylated species and the fragmentation reactions of [C~6~H~5~C(R)OCH~3~]^+^, produced by electron impact ionization of the appropriate methyl ether, were studied as models of the O‐methylated species. From these comparisons it is concluded that methyl cation addition occurs predominantly at the carbonyl oxygen under our experimental conditions. However, for methyl‐cationated acetophenone there is extensive migration of the methyl group from the oxygen to the ring prior to fragmentation of the adduct.

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