Trimethyloxosulfonium chloride

Ion-pair extraction. Iodides are extracted into methylene chloride or similar solvents much more readily than the corresponding chlorides. This ion-exchange method is used to convert trimethyloxosulfonium iodide into the chloride. Thus on distribution of this iodide and an equimolecular amount of the quaternary chloride between methylene chloride and water, the organic phase contains benzyl tri-n-butylammonium iodide and the water phase contains trimethyloxosulfonium chloride. The ion exchange is practically complete. Note that trimethyloxosulfonium chloride is preferred to the iodide for generation of dimethyloxosulfonium methylide because the chloride is more soluble in THF (1,315). ... 

The ylide was prepared by refluxing a mixture of 0.04 mol sodium hydride, 5.12 g (0.04 mol) trimethyloxosulfonium chloride, and 30 mL dry tetrahydrofuran under nitrogen until the evolution of hydrogen ceased ( 2 h). With the reaction mixture held at 55°C, a solution of 3.18 g (0.03 mol) benzaldehyde in 30 mL dry tetrahydrofuran was slowly added dropwise with stirring over a period of 1.5 h and the reaction mixture was then stirred at 55°C for an additional hour. The mixture was concentrated under reduced pressure (generated by a water aspirator) to a volume of 10 mL, then 50 mL water was added. The mixture was extracted with pentane (some resinous material remained in the aqueous phase). The combined pentane extracts were dried over anhydrous sodium sulfate and evaporated the pale yellow residue was evaporatively distilled at 80°C (5.0 mmHg) to yield 2.0 g of colorless styrene oxide, in a yield of 55.6%. 

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