Dimethyl Sulfoxide-Phosphorus Pentoxide1


[67-68-5]  · C2H6OS  · Dimethyl Sulfoxide-Phosphorus Pentoxide  · (MW 78.13) (P2O5)

[1314-56-3]  · O5P2  · Dimethyl Sulfoxide-Phosphorus Pentoxide  · (MW 141.95)

(oxidant for the conversion of primary and secondary alcohols to aldehydes and ketones, respectively; avoids overoxidation to carboxylic acids; modified procedure gives very good yields with short reaction times at 0 °C with minimal formation of byproducts; inexpensive).

Alternate Name: Onodera reagent.

Physical Data: DMSO: mp 18.4 °C; bp 189 °C; d 1.101 g cm-3. P2O5: sublimes 360 °C/760 mmHg.

Solubility: DMSO: sol H2O, alcohol, acetone, THF, CH2Cl2. P2O5: sol H2O.

Form Supplied in: DMSO is a colorless liquid; widely available, including anhydrous grades of DMSO packed under N2; P2O5 (more accurately P4O10) is a white crystalline solid; widely available.

Preparative Method: the active oxidant, formulated as Me2+SO(P2O5)-, is generated in situ from the reaction of DMSO and P2O5 in the presence of the alcohol.

Purification: DMSO: distillation from CaH2 at 56-57 °C/5 mmHg2a or 83-85 °C/17 mmHg;2b storage over 3Å molecular sieves. P2O5: 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;2c Phosphorus(V) Oxide is corrosive and a strong desiccant.

DMSO-P2O5 has long been used,3a but the early procedures involved elevated temperatures with no added base, and required long reaction times, as in the example of eq 1.3b This procedure has been used in conjunction with a reduction step for the inversion of hydroxy group configuration (eq 2).3c More recently the addition of Triethylamine base permits shorter reaction times and lower temperatures, but dry ice temperatures are not required, and this can be an advantage relative to the use of Dimethyl Sulfoxide-Oxalyl Chloride (eq 3).4 The DMSO and P2O5 react to form Me2+SO(P2O5)-, which reacts in situ with the alcohol ROH to give the alkoxysulfonium ion Me2+SOR common to most oxidations by activated DMSO.

Related Reagents.

N-Chlorosuccinimide-Dimethyl Sulfide; Chromic Acid; Dimethyl Sulfide-Chlorine; Dimethyl Sulfoxide-Acetic Anhydride; Dimethyl Sulfoxide-Dicyclohexylcarbodiimide; Dimethyl Sulfoxide-Methanesulfonic Anhydride; Dimethyl Sulfoxide-Oxalyl Chloride; Dimethyl Sulfoxide-Sulfur Trioxide/Pyridine; Dimethyl Sulfoxide-Trifluoroacetic Anhydride; Dimethyl Sulfoxide-Triphosgene; Manganese Dioxide; Pyridinium Chlorochromate; Pyridinium Dichromate; Ruthenium(VIII) Oxide; Silver(I) Carbonate; 1,1,1-Triacetoxy-1,1-dihydro-1,2-benziodoxol-3(1H)-one.

1. (a) Tidwell, T. T. OR 1990, 39, 297. (b) Tidwell, T. T. S 1990, 857. (c) Lee, T. V. COS 1991, 7, 291. (d) Haines, A. H. Methods for the Oxidation of Organic Compounds; Academic: London, 1988. (e) Hudlicky, M. Oxidations in Organic Chemistry; ACS: Washington, 1990. (f) Mancuso, A. J.; Swern, D. S 1981, 165. (g) Moffatt, J. G. In Oxidation; Augustine, R. L.; Trecker, D. J.; Eds.; Dekker: New York, 1971; Vol. 2, Chapter 1.
2. (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.
3. (a) Onodera, K.; Hirano, S.; Kashimura, N. JACS 1965, 87, 4651. (b) Jones, G. H.; Moffatt, J. G. In Methods in Carbohydrate Chemistry; Whistler, R. L.; BeMiller, J. N., Eds; Academic: New York, 1972; Vol. 6, p 315. (c) Moore, B. S.; Cho, H.; Casati, R.; Kennedy, E.; Reynolds, K. A.; Mocek, U.; Beale, J. M.; Floss, H. G. JACS 1993, 115, 5254.
4. (a) Taber, D. F.; Amedio, J. C., Jr.; Jung, K.-Y. JOC 1987, 52, 5621. (b) Taber, D. F.; Amedio, J. C., Jr.; Raman, K. JOC 1988, 53, 2984.

Thomas T. Tidwell

University of Toronto, Ontario, Canada

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