Publisher Summary The most common route to sulfoxides is the oxidation of the corresponding sulfide. This oxidation can be achieved by virtually every class of oxidants. The difficulty is to avoid overoxidation to the sulfone—a step that often occurs with almost the same facility as the first oxidation. A number of other reagents that have been used for the oxidation of sulfides to sulfoxides include iodosobenzene, chromic acid, nitric acid, ozone, and dinitrogen tetraoxide. The last is used in a catalytic cycle for the air oxidation of dimethyl sulfide in industrial processes for di-methyl sulfoxide. Nonoxidative methods for the preparation of sulfoxides include the elaboration of sulfinyl carbanions by addition of electrophiles and the reaction of sulfinyl chlorides with reactive carbon nucleophiles, for example, silylenol ethers. The most important nonoxidative process is the Andersen synthesis of optically pure sulfoxides by the reaction of Grignard reagents with optically pure menthyl sulfinates.