Dimethyl Sulfoxide-Oxalyl Chloride

(DMSO) [67-68-5] C2H6OS (MW 78.13) InChI = 1S/C2H6OS/c1-4(2)3/h1-2H3 InChIKey = IAZDPXIOMUYVGZ-UHFFFAOYSA-N ((COCl)2) [79-37-8] C2Cl2O2 (MW 126.93) InChI = 1S/C2Cl2O2/c3-1(5)2(4)6 InChIKey = CTSLXHKWHWQRSH-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 minimal amounts of byproduct methylthiomethyl ethers) Alternate Name: Swern reagent. Physical Data: DMSO: mp 18.4 °C; bp 189 °C; d 1.101 g cm−3. (COCl)2: bp 63–64 °C/763 mmHg; d 1.455 g cm−3. Solubility: DMSO: sol H2O, alcohol, acetone, THF, CH2Cl2. (COCl)2: reacts H2O; sol CH2Cl2, THF. Form Supplied in: colorless liquids; widely available, including ‘anhydrous’ grades of 99%+ DMSO packed under N2, and 2M (COCl)2 in CH2Cl2 under N2. Preparative Methods: the active reagent, Me2S+Cl, is formed rapidly from DMSO–(COCl)2 at −78 °C in CH2Cl2. Purification: DMSO: distillation from calcium hydride at 56–57 °C/5 mmHg2a or 83–85 °C/17 mmHg;2b storage over 3° molecular sieves. (COCl)2: distillation under N2. 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 Oxalyl Chloride is corrosive and moisture-sensitive, and is said to react explosively with DMSO at rt.