Abstract
15 dimethyl‐hydroxyaryl‐sulfonium chlorides have been prepared by condensing dimethylsulfoxide on hydroxyaromatic compounds with hydrochloric acid. The structure of the sulfonium salts and the mechanism of their formation are discussed. The pyrolysis of those sulfonium chlorides gives a quantitative yield of the corresponding methyl‐hydroxyaryl‐thioethers. The combination of those two reactions provides a very convenient way to introduce a methylthio‐group on an aromatic nucleus already carrying an hydroxyl group.