R₂SO₂ (or RSOOR) A compound formed by the oxidation of sulfides, for example, ethyl sulfone, C₄H₁₀SO₂, from ethyl sulfide, C₄H₁₀S; the use of sulfones, particularly 4,4_-sulfonyldianiline (dapsone) in the treatment of leprosy leads to apparent improvement; relapses associated with sulfone-resistant strains have been encountered.