Dimethyl Sulfoxide-Iodine


[67-68-5]  · C2H6OS  · Dimethyl Sulfoxide-Iodine  · (MW 78.13) (I2)

[7553-56-2]  · I2  · Dimethyl Sulfoxide-Iodine  · (MW 253.81)

(oxidant with diverse applicability, including the conversion of benzoyl methylene groups to di- and triketones, thioacetals to carbonyl compounds, and ketones to a,b-unsaturated ketones)

Physical Data: DMSO: mp 18.4 °C; bp 189 °C; d 1.101 g cm-3. I2: mp 113 °C; bp 184 °C; d 4.930 g cm-3.

Solubility: DMSO: sol H2O, alcohol, acetone, THF, CH2Cl2. I2: sol ether, CHCl3, CS2, aq soln HI.

Form Supplied in: DMSO is a colorless liquid; widely available, including anhydrous grades of 99%+ DMSO packed under N2. I2 is a widely available crystalline solid.

Preparative Methods: the actual reagent may differ from one reaction to another, and the specific procedures also differ.

Purification: DMSO: distillation from calcium hydride at 56-57 °C/5 mmHg1a or 83-85 °C/17 mmHg;1b storage over 3Å molecular sieves. I2: sublimation.

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;1c Iodine is corrosive and toxic.

The formation of dicarbonyl compounds by this reagent is a variation of the Kornblum oxidation2 and presumably involves acid-catalyzed iodination of the carbonyl compound (1) to give an a-iodo ketone (2) which undergoes displacement by DMSO to give an alkoxysulfonium ion (3); this gives a dicarbonyl compound (4) in a 1,2-elimination with assistance by base (eq 1).3a

Reaction of the flavanone (5) to give (6) presumably involves an a-iodo ketone which undergoes elimination (eq 2).3b The ethylene thioacetal of cyclohexanone gives cyclohexanone (eq 3),3c and phosphine sulfides and selenides give the oxo analogs (eq 4).3d

Related Reagents.

Dimethyl Sulfoxide-Acetic Anhydride; Dimethyl Sulfoxide-Dicyclohexylcarbodiimide; Dimethyl Sulfoxide-Methanesulfonic Anhydride; Dimethyl Sulfoxide-Oxalyl Chloride; Dimethyl Sulfoxide-Phosgene; Dimethyl Sulfoxide-Phosphorus Pentoxide; Dimethyl Sulfoxide-Sulfur Trioxide/Pyridine; Dimethyl Sulfoxide-Trifluoroacetic Anhydride; Dimethyl Sulfoxide-Triphosgene.

1. (a) Iwai, I.; Ide, J. OSC 1988, 6, 531. (b) Insalaco, M. A.; Tarbell, D. S. OSC 1988, 6, 207. (c) Corey, E. J.; Chaykovsky, M. OSC 1973, 5, 755.
2. (a) Kornblum, N.; Powers, J. W.; Anderson, G. J.; Jones, W. J.; Larson, H. O.; Levand, O.; Weaver, W. M. JACS 1957, 79, 6562. (b) Kornblum, N.; Jones, W. J.; Anderson, G. J. JACS 1959, 81, 4113. (c) Kilenyi, S. N. COS 1991, 7, 653.
3. (a) Furukawa, N.; Akasaka, T.; Aida, T.; Oae, S. JCS(P1) 1977, 372. (b) Fatma, W.; Iqbal, J.; Ismail, H.; Ishratullah, K.; Shaida, W. A.; Rahman, W. CI(L) 1979, 315. (c) Chattopadhyaya, J. B.; Rao, A. V. R. TL 1973, 3735. (d) Mikolajczyk, M.; Luczak, J. S 1975, 114.

Thomas T. Tidwell

University of Toronto, Ontario, Canada

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