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Fragmentation of trimethylsilyl derivatives of 2‐alkoxyphenols: A further violation of the ‘even‐electron rule’
Author(s) -
Krauss Dietlinde,
Mainx Hans Georg,
Tauscher Bernhard,
Bischof Peter
Publication year - 1985
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210201005
Subject(s) - chemistry , trimethylsilyl , vanillin , radical , ferulic acid , guaiacol , mass spectrum , fragmentation (computing) , phenol , polyatomic ion , medicinal chemistry , organic chemistry , ion , chromatography , computer science , operating system , catalysis
The mass spectra of trimethylsilyl (TMS) ethers of 2‐methoxyphenols show abundant [M–30] + ˙ ions originating from consecutive loss of two methyl radicals. This is illustrated by comparison of the accurate mass‐measured and linked‐scan spectra of the TMS derivatives of 2‐methoxyphenol (guaiacol), 4‐hydroxy‐3‐methoxybenzaldehyde (vanillin) and 3‐(4‐hydroxy‐3‐methoxyphenyl)‐2‐propenoic acid methyl ester (ferulic acid methyl ester) with those of the TMS derivatives of phenol, 4‐hydroxybenzaldehyde, 3‐(4‐hydroxyphenyl)‐2‐propenoic acid methyl ester ( p ‐coumaric acid methyl ester), 3‐methoxyphenol and 4‐methoxyphenol. This distinctive ortho effect is valuable in the identification of isomeric phenolic compounds. In the spectra of the TMS derivatives of 2‐ethoxyphenol and 2‐propoxyphenol the sequential loss of two radicals is less pronounced, because elimination of the side‐chain and a methyl group with rearrangement and hydrogen migration is competitive.