They are compounds similar to ethers in which oxygen is replaced by sulfur (RSR). They are also called sulfides.

They can be synthesized by reaction of thiols and haloalkanes, the reaction is favored in the presence of a basic medium.
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Another way to obtain thioethers is by attack of nucleophiles on disulfides.
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A reaction of great interest is the oxidation of thioethers to sulfides, which in turn can undergo a second oxidation to sulfones. This oxidation can be carried out with hydrogen peroxide, although it is necessary to control the amount added if it is desired to stop at the sulfoxide. Another less energetic oxidizer is sodium periodate, in this case the oxidation stops at sulfoxide.
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