Sodium Iodide → Iodomethyl 2-ethylbutanoate

2-Ethyl butyric acid chloromethyl ester (700 g) was dissolved in acetone (3 L). To this solution was added sodium iodide (1.0 kg). The resulting reaction mixture was heated at reflux until reaction completion (2 h (hours), monitored by GC). The solution was then cooled to ambient temperature where tert-butyl methyl ether (7 L) and 5% aqueous sodium thiosulfate (4 L) were added. The phases were separated and the organic phase was washed with aqueous sodium thiosulfate (4 L), low pyrogen water (4 L) and 10% sodium chloride solution (4 L). The organic layer was dried over magnesium sulfate (350 g), filtered, and the filter cake was washed with tert-butyl methyl ether (2×0.7 L). The filtrate was evaporated to a small volume (ca. 2 L) to give 2-ethyl butyric acid iodomethyl ester, as a solution in tert-butyl methyl ether.