Dimethyl Sulfoxide-Acetic Anhydride

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(DMSO) [67-68-5] C2H6OS (MW 78.13) InChI = 1S/C2H6OS/c1-4(2)3/h1-2H3 InChIKey = IAZDPXIOMUYVGZ-UHFFFAOYSA-N (Ac2O) [108-24-7] C4H6O3 (MW 102.09) InChI = 1S/C4H6O3/c1-3(5)7-4(2)6/h1-2H3 InChIKey = WFDIJRYMOXRFFG-UHFFFAOYSA-N (oxidant for the conversion of primary and secondary alcohols to aldehydes and ketones, respectively; avoids overoxidation to carboxylic acids; suitable for large-scale oxidation; gives good yields with variable amounts of byproduct methylthiomethyl ethers) Alternate Name: Albright–Goldman reagent. Physical Data: DMSO mp 18.4 °C; bp 189 °C; d 1.101 g cm−3. Ac2O: mp −78 °C; bp 138–140 °C; d 1.082 g cm−3. Solubility: DMSO: sol H2O, alcohol, acetone, THF, CH2Cl2. Ac2O: sol ether, acetone, CH2Cl2. Form Supplied in: colorless liquids; widely available, including ‘anhydrous’ grades of DMSO packed under N2. Preparative Method: the active reagent, presumably Me2S+OAc, forms slowly from a mixture of the coreactants over a period of hours at rt and reacts with the alcohol in situ. Purification: DMSO: distillation from calcium hydride at 56–57 °C/5 mmHg2a or 83–85 °C/17 mmHg;2b storage over 3A molecular sieves. Ac2O: distillation from aluminum chloride or calcium carbide. Handling, Storage, and Precautions: Dimethyl Sulfoxide is readily absorbed through the skin and should always be handled with gloves in a fume hood; its reactions form foul-smelling byproducts and should be carried out with good ventilation, and the waste byproducts and liquids used for washing should be treated with KMnO4 solution to oxidize volatile sulfur compounds; DMSO undergoes appreciable disproportionation to dimethyl sulfide (stench) and dimethyl sulfone above 90 °C;2c Acetic Anhydride is a corrosive lachrymator.