Premium
Cyclic ions in the mass spectra of trimethylsilyl derivatives of substituted o ‐dihydroxybenzenes
Author(s) -
Horvat Robert J.,
Senter Samuel D.
Publication year - 1983
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.1210181002
Subject(s) - chemistry , trimethylsilyl , mass spectrum , medicinal chemistry , ion , derivatization , base (topology) , moiety , mass spectrometry , organic chemistry , chromatography , mathematical analysis , mathematics
The mass spectra of trimethylsilyl (TMS) ethers/methyl esters of phenolic acids containing o ‐dihydroxybenzene groups have base peaks at [M−119] + instead of the usual [M−15] + and [M−31] + that are characteristic of TMS/methyl esters of monohydroxyphenolic acids. These ions, formed by the loss of 31+88 u from the parent ion, possess a cyclic moiety as proven by substitution of deuterium atoms for hydrogen atoms in the TMS groups of the methyl esters of 3,4,5‐trihydroxybenzoic (gallic), 3,4‐dihydroxybenzoic (protocatechuic) and β‐(3,4‐dihydroxyphenyl)propenoic (caffeic) acids. Although these cyclic ions are the base peaks in TMS‐derivatized o ‐dihydroxyphenolic acid esters, similar ions represent intense peaks but not necessarily the base peak in other derivatized compounds such as 1,2‐dihydroxybenzene, 1,2‐dihydroxy‐3‐methyl‐ and 1,2‐dihydroxy‐4‐methyl‐benzenes and flavan‐3‐ols that possess o ‐dihydroxybenzene groups. Compounds possession m ‐ or p ‐dihydroxybenzene groups do not form these cyclic ions; therefore, this procedure for derivatization and interpretation of mass spectra is valuable for the identification of compounds containing o ‐dihydroxybenzene groups in complex mixtures of isomeric compounds.