[172387-03-5] · C3H10OS · Trimethylsulfonium Hydroxide · (MW 94.20)
(quantitative pyrolytic O-alkylation of fatty acids during gas chromatographic analysis)
Preparative Methods: by treating Trimethylsulfonium Iodide with Silver(I) Oxide in methanol;2 by electrochemical method;3 and in aqueous solution, by treating trimethylsulfonium iodide with Tetra-n-butylammonium Hydroxide using an extraction procedure.1 The reagent has been reported to be stable in cool methanol for at least six months.4
Trimethylsulfonium hydroxide is primarily referred to in the literature as a reagent for derivatizing fatty acids during gas chromatographic analysis through pyrolytic alkylation (eq 1).5
The transformation takes place in the injection port, alleviating the need for more time consuming methods. Alternative methods include basic hydrolysis followed by acid-catalyzed re-esterification,6 transesterification with sodium methoxide,7 pyrolytic alkylation using a trialkylselenonium hydroxide,4 and pyrolytic alkylation using a quaternary ammonium hydroxide.8 Each of these methods has limitations. Hydrolysis and re-esterification require a significant amount of laboratory time. The transesterification using sodium methoxide fails to derivatize any free acids present in the initial mixture. Selenium reagents have handling problems due to their toxicity. Amine byproducts from a quaternary ammonium hydroxide have sufficiently long retention times to complicate a chromatogram.
Yamauchi has used trimethylsulfonium hydroxide to 2´-O-methylate pyrimidine ribonucleosides selectively.9 A variety of metal ion catalysts for this methylation procedure were evaluated on a semipreparative scale.
The use of trimethylsulfonium hydroxide as a pyrolytic O-alkylating agent avoids many of the problems associated with other methods. The reagent is conveniently prepared from readily available starting materials and is relatively stable in solution.
Great Lakes Chemical Corporation, West Lafayette, IN, USA