THE CHARACTERIZATION OF SULFONIUM CHLORIDES BY GAS CHROMATOGRAPHY/MASS SPECTROMETRY AND THE DEGRADATION OF 2-CHLOROETHYL SULFIDE DERIVATIVES

Abstract

Three aqueous samples containing sulfonium chloride salts of both mustard gas (2,2′-dichlorodiethyl sulfide) and its simulant 2-chloroethyl ethyl sulfide have been characterized by gas chromatography/mass spectrometry (GC/MS). These salts decompose thermally to the corresponding 2-chloroethyl and 2-hydroxyethyl sulfides, therefore GC/MS analysis is not indicative of the true composition of these solutions. Small amounts of dithioethers characteristic of the decomposition of the dimeric salts were also detected. Electron Impact (EI) ionization produces a more intense molecular ion than methane chemical ionization (CI) for the dithioethers because of the ease of formation of sulfonium ions during chemical ionization.

The decomposition products of four aged samples of 2-chloroethyl sulfides (RSCH₂CH₂,Cl where R = methyl, ethyl, phenyl and benzyl groups) were also characterized by GC/MS, which indicated that decomposition of these compounds may proceed via dimeric sulfonium ions. Mustard gas was detected in all but one of the samples, providing evidence for secondary sulfonium cation formation in the degradation process.

Key Words:

• Sulfonium chlorides
• 2-chloroethyl sulfides
• degradation
• dimeric sulfonium cations
• GC/MS characterization