Sulfoxides dimethylsulfoxide

Mixtures which are Unstable or Explosive Dimethyl Sulfoxide. A violent expin occurs when a drop of 70% perchloric ac is added to 10ml of dimethylsulfoxide (Ref 40)... 

Polymers containing pendant carbamate functional groups can be prepared by the reaction of phenyl isocyanate with poly(vinyl alcohol) in homogeneous dimethylsulfoxide solutions using a tri-ethylamine catalyst. These modified polymers are soluble in dimethyl sulfoxide, dimethylacetamide, dimethylformamide and formic acid but are insoluble in water, methanol and xylene. Above about 50% degree of substitution, the polymers are also soluble in acetic acid and butyrolactone. The modified polymers contain aromatic, C = 0, NH and CN bands in the infrared and show a diminished OH absorption. Similar results were noted in the NMR spectroscopy. These modified polymers show a lower specific and intrinsic viscosity in DMSO solutions than does the unmodified poly(vinyl alcohol) and this viscosity decreases as the degree of substitution increases. 

Oae and co-workers (288) were the first to show that nucleophilic displacement at sulfur is accompanied by retention of configuration. They found that chiral 0-labeled alkyl aryl sulfoxides exchange oxygen with dimethylsulfoxide at about 150°C, almost without racemization. To explain the steric course (retention) of this reaction, the formation of a trigonal-bipyramidal intermediate 246 was postulated in which the entering and departing oxygen atoms occupy apical and equatorial positions, respectively. 

D. TRIS(DIMETHYL SULFOXIDE)INDIUM(III) BROMIDE [TRIBROMO-TRIS(DIMETHYLSULFOXIDE)INDIUM(III)j... 

Swern oxidations have been performed using the PEG2000 bound sulfoxide 34 as a dimethylsulfoxide (DMSO) substitute (reaction 13).49-50 Several alcohols were efficiently oxidized to their aldehydes or ketones using this reagent, oxalyl chloride, and triethylamine. Precipitation of the polymer with cold diethyl ether and filtration through a pad of silica afforded the desired oxidized products in very good yields and purities. The reduced sulfide polymer could be reoxidized to sulfoxide 34 with sodium metaperiodate and used again in reactions with no appreciable loss in oxidation capacity. 

Isatin, JV-methylisatin, and JV-hydroxyisatin can be reduced to semidiones by treatment with the enolate anion of propiophenone in dimethylsulfoxide.258 Nitroxides are prepared from iV-hydroxyisatin by treatment with lead dioxide in dioxan, while another nitroxide was formed spontaneously from iV-hydroxyisatin in basic dimethyl sulfoxide solution in the presence of oxygen.256... 

To a 250 ml flask equipped with a stirrer, a thermometer, a water condenser and Dean-Stark trap was added 11.42 g of 4.4 -isopropylidenediphenol (0.05 moles), 13.1 g of a 42.8% potassium hydroxide solution (0.1 mole KOH), 50 ml of dimethyl sulfoxide and 6 ml of benzene. The reaction mixture was kept under an atmosphere of nitrogen and the water was azeotroped oft over a 3 to 4 hours period (130—135° C). At the end of this time the reaction mixture consisted of the potassium salt of the biphenol and was essentially anhydrous. After cooling the mixture there was added 14.35 g (0.05 moles) of 4.4 -dichlorodiphenyl sulfone and 40 ml of anhydrous dimethylsulfoxide. The reaction mixture was maintained, under a nitrogen atmosphere, between 130 and 140° C with stirring for 4 to 5 hours. The viscous orange solution was then poured into 300 ml of water in a Waring Blendor and the polymer separated by filtration and dried at 110° for 16 hours. A yield of 22.2 g (100%) of polymer with a reduced viscosity in chloroform (0.2 g per 100 ml at 25°) of 0.59 was obtained. 

The preparation of 6.102 is carried out in a variety of solvents, such as DMF, DMA, dimethylsulfoxide (DMSO) and ethyl methyl sulfoxide, at 80°C and the yield of the carcerand is virtually quantitative. 

Oxidation of DMS to DMSO and DMSO. DMS is chemically and biochemically oxidized to dimethylsulfoxide (DMSO). Mechanisms for the in situ oxidation of DMS to DMSO in seawater have received little attention, even though this may be an important sink for DMS. Hydrogen peroxide occurs in surface oceanic waters (22) and is produced by marine algae (98). It may participate in a chemical oxidation of DMS, since peroxide oxidizes sulfides to sulfoxides (991. Photochemical oxidation of DMS to DMSO occurs in the atmosphere and DMSO is found in rain from marine regions (681. DMS is also photo-oxygenated in aqueous solution to DMSO if a photosensitizer is present natural compounds in coastal seawater catalyzed photo-oxidation at rates which may be similar to those at which DMS escapes from seawater into the atmosphere (1001. 

Other Polymers. Other hydrophilic polymers also exhibit the shear stiffness anomaly when contacted with hydrogen bonding solvents. Films of amylose respond to water and dimethylsulfoxide as shown in Table III. When wet with water, there is a comparatively large increase in attenuation followed by a slow decline to a level plateau. We attribute this leveling out to the comparative water insolubility of retrograded amylose. Dimethyl sulfoxide is a much stronger solvent for amylose than is water and the increase in stiffness which is followed by a rapid decay to zero indicates complete film solution as was the case with water on PVA. The... 

SAFETY PROFILE Poison by inhalation and ingestion. A corrosive eye, skin, and mucous membrane irritant. Potentially explosive reaction with water evolves hydrogen chloride and phosphine, which then ignites. Explosive reaction with 2,6-dimethylpyridine N-oxide, dimethyl sulfoxide, ferrocene-1,1 -dicarboxylic acid, pyridine N-oxide (above 60°C), sodium -L heat. Violent reaction or ignition with BI3, carbon disulfide, 2,5-dimethyl pyrrole + dimethyl formamide, organic matter, zinc powder. Reacts with water or steam to produce heat and toxic and corrosive fumes. Incompatible with carbon disulfide, N,N-dimethyl-formamide, 2,5-dimethylpyrrole, 2,6-dimethylpyridine N-oxide, dimethylsulfoxide, ferrocene-1,1-dicarboxylic acid, water, zinc. When heated to decomposition it emits highly toxic fumes of Cl" and POx. 

The very well established chemical technique of using potassium superoxide or ammonium superoxide suffers from the pH instability described in reactions (15) to (17) the superoxide is only stable at very high pH, or the use of an organic solvent, most often dimethyl-sulfoxide (DMSO). Still a great number of very impressive studies were carried out using stopped flow technique combined with potassium superoxide in dimethylsulfoxide, particularly by Fee and co-workers and then by Silverman and co-workers. ... 

Studies to isolate novel halochalcogenous acids from nonaque-ous solvents have lead to a reaction product of composition H2TeCl6 4(CH3)2S0 when tellurium(IV) chloride was reacted with the system dimethylsulfoxide/HCl/H20 191,192, 427). In the crystalline compound that was isolated from this system, protonated sulfoxide molecules (i.e., sulfoxonium cations [(CH3)2SOH ]) are observed. They are highly interesting and had previously been postulated from strongly acidic solutions. They are present in addition to un-... 

Dimethyl sulfoxide-Acetic anhydride, 199 Dimethylsulfoxide-N-Bromosuccinimide, 199-200... 

Similarly, ethyl l-cyanocyclopropane-l-carboxylates4 and diethyl cyclopropane-1,1-dicar-boxylates 3 were obtained when ethyl dibromocyanoacetate and diethyl dibromomalonate, respectively, were employed. These transformations occur more readily and with higher yields in an aprotic dipolar solvent such as dimethyl sulfoxide. Instead of copper/iodine, copper(I) bromide in dimethylsulfoxide can be applied.In both cases, an equimolar amount of copper (copper salt) is suflTicient, and the cyclopropanation is nonstereospecific [as shown for 1-phenyl-prop-l-ene (Table 1)]. A stepwise, radical mechanism is likely to operate in these transformations. 

Estimate the contributions to the van der Waals energy in dimethylsulfoxide at 25° C by considering two molecules in contact as hard spheres with diameters of 491 pm. The dipole moment of dimethyl sulfoxide is 3.96 debyes, its polarizability, 7.99 X 10 nm, and its ionization potential, 9.01 eV. 

Fig. 10. N-ENDOR spectra at 10 K of mixed-valent MMOH (resting and dimethyl-sulfoxide complex) and Hr (sulfide complex). Resting MMOH in 0.1 M MOPS pH 7.0, cw ENDOR spectra obtained atgi = 1.94. Dimethylsulfoxide (0.3 M) complexed MMOH at 0.1 M MOPS pH 6.5, cw ENDOR spectra obtained at gi = 1.94. Hr sulfide complex at pH 8, cw ENDOR spectra obtained at gi = 1.88. The bars labeled Fe(III)-N mark the resonances for nitrogen coordinated to FefllD. The resonances at low frequency observed in absence of dimethylsulfoxide are from the nitrogen coordinated to Fe(II). Adapted from (237).

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