Deprotonation of DMSO requires strong bases like lithium diisopropylamide and sodium hydride. Stabilization of the resultant carbanion is provided by the S(O)R group. The sodium derivative of DMSO formed in this way is referred to as dimsyl sodium. It is a base, e.g., for the deprotonation of ketones to form sodium enolates, phosphonium salts to form Wittig reagents, and formamidinium salts to form diaminocarbenes. It is also a potent nucleophile. Oxidant
In organic synthesis, DMSO is used as a mild oxidant. It forms the basis of several selective sulfonium-based oxidation reactions include the Pfitzner–Moffatt oxidation, Corey–Kim oxidation and the Swern oxidation. The Kornblum oxidation is conceptually similar. These all involve formation an intermediate sulfonium species (R2S+X where X is a heteroatom)

Ligand and Lewis base
Related to its ability to dissolve many salts, DMSO is a common ligand in coordination chemistry. Illustrative is the complex dichlorotetrakis(dimethyl sulfoxide)ruthenium(II) (RuCl2(dmso)4). In this complex, three DMSO ligands are bonded to ruthenium through sulfur. The fourth DMSO is bonded through oxygen. In general, the oxygen-bonded mode is more common. In carbon tetrachloride solutions DMSO functions as a Lewis base with a variety of Lewis acids such as I2, phenols, trimethyltin chloride, metalloporphyrins, and the dimer Rh2Cl2(CO)4. The donor properties are discussed in the ECW model. The relative donor strength of DMSO toward a series of acids, versus other Lewis bases, can be illustrated by C-B plots. Applications
Solvent
DMSO is a polar aprotic solvent and is less toxic than other members of this class, such as dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, and hexamethylphosphoramide (HMPA).
See also
Varying oxidation of sulfur
Dimethyl sulfide (DMS), the corresponding sulfide, also produced by marine phytoplankton and emitted to the oceanic atmosphere where it is oxidized to DMSO, SO2 and sulfate
Dimethyl sulfone, commonly known as methylsulfonylmethane (MSM), a related chemical often marketed as a dietary supplement
Related compounds with methyl on oxygen
Dimethyl sulfite, the corresponding sulfite
Dimethyl sulfate (also DMS), the corresponding sulfate: a mutagenic alkylating compound
Methyl methanesulfonate, another methylating agent
Gloria Ramirez, also known as the "Toxic Woman"

References
External links

International Chemical Safety Card 0459
Dimethyl Sulfoxide Information Center