Dimethyl sulfoxide , chromium

C. HEXAKIS(DIMETHYL SULFOXIDE)CHROMIUM(III) BROMIDE, [Cr-(DMSO)6]Br3... 

Strong acids and strong alkaUes can severely bum the skin, chromium compounds can produce skin rashes, and repeated exposure to solvents causes removal of natural oils from the skin. Infection is always a concern for damaged skin. Absorption through the skin is possible for materials that are appreciably soluble iu both water and oil, eg, nitrobenzene, aniline, and tetraethyllead. Other materials can be absorbed if first dissolved iu extremely good solvents, eg, dimethyl sulfoxide. Subcutaneous iujection can occur accidentally by direct exposure of the circulatory system to a chemical by means of a cut or scratch or iuadvertent penetration of the skin with a hypodermic needle. 

Solvent for Electrolytic Reactions. Dimethyl sulfoxide has been widely used as a solvent for polarographic studies and a more negative cathode potential can be used in it than in water. In DMSO, cations can be successfully reduced to metals that react with water. Thus, the following metals have been electrodeposited from their salts in DMSO cerium, actinides, iron, nickel, cobalt, and manganese as amorphous deposits zinc, cadmium, tin, and bismuth as crystalline deposits and chromium, silver, lead, copper, and titanium (96—103). Generally, no metal less noble than zinc can be deposited from DMSO. 

Vicinal glycols may be oxidized to the corresponding 17a-hydroxy-20-ketones in reasonable yields by means of chromium trioxide in dimethylfor-mamide in the presence of manganese dichloride, or by treatment with dimethyl sulfoxide-acetic anhydride. ... 

Chromium, hexacyano-, 3, 703, 777 hexaamminecobaltate coordination isomerism, 1, 183 ligand field photochemistry, 1, 398 photochemistry excited states, 1, 398 production, 3, 704 Chromium, hexafluoro-, 3, 927 Chromium, hexabalo-, 3, 889 Chromium, hexaiodo-, 3, 766 Chromium, hexakis(dimethyl sulfoxide)-photoanation, 1, 399 Chromium, u-oxalatodi-reduction... 

See Chromium(III) perchlorate. 6 dimethyl sulfoxide Magnesium perchlorate Dimethyl sulfoxide Mercury(II) perchlorate. 6(or 4)dimethyl sulfoxide Silver perchlorate Dimethyl sulfoxide See Perchloric acid Sulfoxides... 

Copper(II) sulfate Cumene hydroperoxide Cyanides Cyclohexanol Cyclohexanone Decaborane-14 Diazomethane 1,1-Dichloroethylene Dimethylformamide Hydroxylamine, magnesium Acids (inorganic or organic) Acids, water or steam, fluorine, magnesium, nitric acid and nitrates, nitrites Oxidants Hydrogen peroxide, nitric acid Dimethyl sulfoxide, ethers, halocarbons Alkali metals, calcium sulfate Air, chlorotrifluoroethylene, ozone, perchloryl fluoride Halocarbons, inorganic and organic nitrates, bromine, chromium(VI) oxide, aluminum trimethyl, phosphorus trioxide... 

These and related incidents are detailed under f Acetonitrile, Lanthanide perchlorate, 0758 Chromium(III) perchlorate. 6 dimethyl sulfoxide Cobalt(II) perchlorate hydrates, 4051... 

All of the usual chromium-based oxidation reagents that have been used for the oxidation of cyclobutanols to cyclobutanones, for example, chromium(VI) oxide (Jones reagent),302 pyri-dinium chlorochromate,304 pyridinium dichromate,307 and chromium(YI) oxide/pyridine (Collins),303 are reported to do so without any serious problems. Alternatively, tetrapropylam-monium perruthenate in the presence of A-methylmorpholine A -oxide. oxalyl chloride in the presence of triethylamine in dimethyl sulfoxide (Swern),158,309,310 or phenyl dichlorophos-phate in the presence of triethylamine and dimethyl sulfoxide in dichloromethane (Pfitzner-Moffatt),308 can be used. The Pfitzner-Moffatt oxidation procedure is found to be more convenient than the Swern oxidation procedure, especially with respect to the strict temperature control that is necessary to achieve good yields in the latter, e.g. oxidation of 1 to give 2.308... 

The above discussion has concentrated upon the reagents used, but it is equally of value to comment on the substrate, particularly in reactions for which other oxidation methods have been reported to fail. A good example is the oxidation of the iron-carbonyl complex (31) to the ketone (32 equation 14). The use of dimethyl sulfoxide activated with sulfur trioxide-pyridine complex gave a 70% yield of the product, in contrast to the use of the Pfitzner-Moffatt procedure (dimethyl sulfoxide-DCC) or the chromium... 

Although many oxidizing reagents remove the chromium tricarbonyl group, benzylic alcohols can be oxidized to benzaldehydes using dimethyl sulfoxide with acetic anhydride, trifluoroacetic anhydride, or sulfurtrioxide with minimal decomplexation. Asymmetric oxidation of aUcylthio-substituted complexes can be achieved using titanium tetraisopropoxide and an optically active tartrate ester (Scheme 108). Dimethyloxirane can also be used to oxidize sulfides to sulfoxides. 

SAFETY PROFILE Poison by ingestion and inhalation. A corrosive irritant to skin, eyes (at 2 ppm), and mucous membranes. Potentially explosive reaction with chlorobenzene + sodium, dimethyl sulfoxide, molten sodium, chromyl chloride, nitric acid, sodium peroxide, oxygen (above 100°C), tetravinyl lead. Reacts with carboxylic acids (e.g., acetic acid) to form violently unstable products. Violent reaction or ignition with Al, chromium pentafluoride, diallyl phosphite + allyl alcohol, F2, hexafluoroisopropylideneaminolithium, hydroxylamine, iodine chloride, PbOa, HNO2, organic matter, potassium, selenium dioxide, sulfur acids (e.g., sulfuric acid. 

Other hazardous reactions may occur with carbon (e.g., soot, graphite, activated charcoal), dimethyl sulfoxide, ethylene oxide, chlorine, bromine vapor, hydrogen bromide, potassium iodide + magnesium bromide, chloride or iodide, maleic anhydride, mercury, copper(II) oxide, mercury(II) oxide, tin(IV) oxide, molybdenum(III) oxide, bismuth trioxide, phosphoms trichloride, sulfur dioxide, chromium trioxide. 

In contrast, the chemistry of the oxidation of a primary alcohol to an aldehyde differs sharply from the oxidation of an aldehyde to a carboxylic acid (case (b)). Advantage, in this case, must be taken of the difference in the mechanisms of these steps. Among the reagents which can effectively oxidize alcohols and remain rather inert toward aldehydes are pyridinium chlorochro-mate (a chromium trioxide-hydrogen chloride complex of pyridine) or dimethyl sulfoxide-Lewis acid. 

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