[23403-17-0] · Cl9K3W2 · Tripotassium Nonachloroditungstate(III) · (MW 804.05)
(reduces sulfoxides to sulfides1)
Alternate Name: potassium tri-m-chlorohexachloroditungstate(III).
Solubility: sol methanol, water, aqueous HCl.
Form Supplied in: green crystals; not commercially available.
Preparative Methods: prepared in a three-step procedure from tungsten trioxide trihydrate.2 First, tungsten trioxide trihydrate is treated with aqueous potassium carbonate, followed by hydrogen chloride gas, followed by reduction with tin metal.
Purification: recrystallized from aqueous HCl.
Sulfoxides are reduced to sulfides by treatment with the title reagent in refluxing methanol (eq 1).1 The reaction is very specific for the reduction of sulfoxides and not sulfones or sulfimines. Other functional groups not reduced by this reagent include organic halides, phosphine oxides, epoxides, ketones, esters, nitriles, and aromatic nitro compounds. In one report, a vinylic sulfoxide amino acid was efficiently reduced (eq 2).3 The major disadvantage of this reagent is that it is not commercially available. For a listing of other methods to effect this transformation, see Madesclaire.4
James W. Herndon
University of Maryland, College Park, MD, USA