Preparation of [¹⁸O]‐chlorocarbonylsulfenyl chloride

[¹⁸O]‐Chlorocarbonylsulfenyl chloride with an isotopic purity of 92% was prepared in three steps starting with the [¹⁸O]‐hydrolysis of 2‐ethyl‐1,3‐dioxolane to [¹⁸O]‐propanal, which was then converted to [¹⁸O]‐O‐1‐methylpropyl S‐methyl dithiocarbonate, which was then chlorinated to give the title compound. Distilled yields for the three steps were 57%, 49%, and 40% respectively.