Sulfonium Ions (sulfonium + ion)

Distribution by Scientific Domains


Selected Abstracts


,- and ,-Glycosyl Sulfonium Ions: Generation and Reactivity

CHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2009
Toshiki Nokami Dr.
Abstract Low-temperature electrochemical oxidation of thioglycosides gave glycosyl triflates from which glycosyl sulfonium ions were produced (see scheme). The latter were characterized by NMR spectroscopy and cold-spray mass spectrometry as a mixture of ,- and ,-isomers (45:55). The ,-glycosyl sulfonium ion exhibited higher reactivity than the ,-glycosyl sulfonium ion in the reaction with methanol, which gave a mixture of ,- and ,-methyl glycosides (41:59). [source]


Dimerization of ionized 4-(methyl mercapto)-phenol during ESI, APCI and APPI mass spectrometry

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 9 2009
Lianming Wu
Abstract A novel ion/molecule reaction was observed to occur under electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photo ionization (APPI) conditions, leading to dimerization of ionized 4-(methyl mercapto)-phenol followed by fast H loss. The reaction is particularly favored during ESI, which suggests that this ion/molecule reaction can occur both in the solution inside the ESI-charged droplets and in the gas-phase environment of most other atmospheric pressure ionization techniques. The dimerization reaction is inherent to the electrolytic process during ESI, whereas it is more by ion/molecule chemistry in nature during APCI and APPI. From the tandem mass spectrometry (MS/MS) data, accurate mass measurements, hydrogen/deuterium (H/D) exchange experiments and density functional theory (DFT) calculations, two methyl sulfonium ions appear to be the most likely products of this electrophilic aromatic substitution reaction. The possible occurrence of this unexpected reaction complicates mass spectral data interpretation and can be misleading in terms of structural assignment as reported herein for 4-(methyl mercapto)-phenol. Copyright 2009 John Wiley & Sons, Ltd. [source]


,- and ,-Glycosyl Sulfonium Ions: Generation and Reactivity

CHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2009
Toshiki Nokami Dr.
Abstract Low-temperature electrochemical oxidation of thioglycosides gave glycosyl triflates from which glycosyl sulfonium ions were produced (see scheme). The latter were characterized by NMR spectroscopy and cold-spray mass spectrometry as a mixture of ,- and ,-isomers (45:55). The ,-glycosyl sulfonium ion exhibited higher reactivity than the ,-glycosyl sulfonium ion in the reaction with methanol, which gave a mixture of ,- and ,-methyl glycosides (41:59). [source]