DMSO is a polar aprotic solvent used in selected SN2 substitution reactions. It can provide a medium in which an anionic nucleophile reacts with a suitable organic electrophile.
Why the solvent changes reactivity
DMSO solvates ions differently from protic solvents. This can change nucleophile reactivity, while counterion, ion pairing, salt concentration and water still influence the result.
The substrate remains decisive. Steric hindrance and leaving-group behavior affect substitution, and elimination may compete. Solvent polarity cannot compensate for an unsuitable electrophile.
Check the desired transformation
Selected imidazole and triazole preparations list DMSO among their solvent choices. For any proposed alkylation, verify the actual bond formed and monitor side reactions. Suitable alkyl electrophiles can also undergo DMSO-involving oxidation.
Compare conversion, selectivity and isolation with the established process. Set water and impurity requirements from those results rather than assigning one grade to all SN2 chemistry.
Base compatibility needs its own review. Sodium hydride/DMSO mixtures have documented explosion hazards and should not be treated as a routine solvent/base combination.
For sourcing, provide YUJI with the substrate step and required DMSO quality parameters.
Technical references
Further reading: DMSO in SNAr Reactions; DMSO in Halex Fluorination.