Dimethylsulfoxide, as solvent

K Barlos, D Gatos. 9-Fluorenylmethyloxycarbonyl/rt>utyl-based convergent protein synthesis, (dimethylsulfoxide as solvent) Biopolymers (Pept Sci) 51, 266, 1999. 

It has recently been found that the rearrangement of 19 and 20 to 2-acyl quinolines, such as 35, and 1-acylisoquinolines can be conveniently carried out in dimethylformamide at room temperature. A number of quinolyl and isoquinolyl ketones have been prepared in this manner. Use of dimethylsulfoxide as solvent also allows rearrangement to proceed at room temperature but the initially formed ketones reacted further with the solvent anion to give products such as 37. ... 

If the crown catalyzed reaction of potassium superoxide with alkyl halide is carried out in dimethylsulfoxide as solvent, the product is the corresponding alcohol [6—9]. The formation of alcohol rather than dialkyl peroxide has been shown to result from reaction of the alkyl hydroperoxide anion with dimethylsulfoxide to form alkoxide and dimethylsulfone (Eqs. 8.3-8.5) [9]. The alkyl hydroperoxide anion is presumably formed by reduction of the initial alkyl hydroperoxide radical by the superoxide anion [8, 9]. 

Selenium dioxide oxidizes 1,2-diarylethanones to corresponding diones in about 8 h. The same oxidation was carried out under microwave radiations by Shirude et al. (2006) by using dimethylsulfoxide as solvent, the reaction time was reduced considerably (30 to 90 sec). 

An inert solvent such as benzene, toluene or xylene, or an excess of the alcohol corresponding to the alkoxide is often used as solvent. When a dipolar aprotic solvent such as A,A-dimethylformamide (DMF) or dimethylsulfoxide (DMSO) is used, the reaction often proceeds at higher rate. 

Note It is reported that the use of chlorobenzene as solvent is essential when the reagent is to be used to detect aromatic amines [1]. In the case of steroids, penicillins, diuretics and alkaloids the reaction should be accelerated and intensified by spraying afterwards with dimethylsulfoxide (DMSO) or dimethylformamide (DMF), indeed this step makes it possible to detect some substances when this would not otherwise be possible [5,9-11] this latter treatment can, like heating, cause color changes [5,9]. Penicillins and diuretics only exhibit weak reactions if not treated afterwards with DMF [10, 11]. Steroids alone also yield colored derivatives with DMSO [9]. Tlreatment afterwards with diluted sulfuric acid (c = 2 mol/L) also leads to an improvement in detection sensitivity in the case of a range of alkaloids. In the case of pyrrolizidine alkaloids it is possible to use o-chloranil as an alternative detection reagent however, in this case it is recommended that the plate be treated afterwards with a solution of 2 g 4-(dimethyl-amino)-benzaldehyde and 2 ml boron trifluoride etherate in 100 ml anhydrous ethanol because otherwise the colors initially produced with o-chloranil rapidly fade [12]. 

In an industrial application dissolution/reprecipitation technology is used to separate and recover nylon from carpet waste [636]. Carpets are generally composed of three primary polymer components, namely polypropylene (backing), SBR latex (binding) and nylon (face fibres), and calcium carbonate filler. The process involves selective dissolution of nylon (typically constituting more than 50wt% of carpet polymer mass) with an 88 wt % liquid formic acid solution and recovery of nylon powder with scCC>2 antisolvent precipitation at high pressure. Papaspyrides and Kartalis [637] used dimethylsulfoxide as a solvent for PA6 and formic acid for PA6.6, and methylethylketone as the nonsolvent for both polymers. 

Tetraazamacrocyclic complexes131 of cobalt and nickel were found110 to be effective in facilitating the reduction of C02 at -1.3 to -1.6 V versus SCE (Table 8). An acetonitrile-water mixture and water were used as solvents, while in dry dimethylsulfoxide no catalytic reduction of C02 took place. Using an Hg electrode, both CO and H2 were produced, where total current efficiencies were greater than 90%. The turnover numbers of the catalysts were 2-9 h 1. The catalytic activity lasted for more than 24 h and the turnover numbers of the catalysts exceeded 100. A protic source was required to produce both CO and H2, and the authors suggested that both products may arise from a common intermediate, which is most likely a metal hydride. The applied potential for C02 reduction was further reduced by using illuminated p- Si in the presence of the above catalysts.111... 

There are several cases of hydroxylation according to the hidden radical mechanism, within a solvent cage. As assumed (Fomin Skuratova 1978), hydroxylation of the anthraquinone sulfonic acids (AQ-SO3H) proceeds by such a pathway, and OH radicals attack the substrate anion radicals in the solvent cage. Anthraquinone hydroxyl derivatives are the final products of the reaction. In the specific case of dimethylsulfoxide as a solvent, hydroxyl radicals give complexes with the solvent and lose their ability to react with the antraquinone sulfonic acid anion radicals (Bil kis Shein 1975). The reaction is stopped just after anion radical formation, Scheme 1-102 ... 

Persistent interactions are not limited to hydrogen bonds. We mention for example those appearing in solutions of molecules with a terminal C=0 or C=N group dissolved in liquids such as acetone or dimethylsulfoxide. These solvents prefer at short distances an antiparallel orientation which changes at greater distances to a head-to-tail preferred orientation. The local antiparallel orientation is somewhat reinforced by the interaction with the terminal solute group and it is detected by the PCM calculation of nuclear shielding and vibrational properties. Recent experimental correlation studies [25] have confirmed the orientational behaviour of these solvents found in an indirect way from continuum calculations. The physical effect found in this class of solvent-solute pairs seems to be due to dispersion forces. 

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... 

Matsuda introduced carboxyl groups to wood meal using dicarboxylic anhydrides. Maleic (MA), succinic (SA), and phthalic anhydride (PA) were used as acid anhydrides, N,A -dimethylbenzylamine was used as a catalyst, and dimethylsulfoxide (DMSO) or dimethylformamide (DMF) was used as solvent [14]. The carboxyl groups in the esterified wood were then further reacted with epichlorohydrin to produce oligoesterified woods. A detailed description of these reactions is given in Chapter 6. 

Amphiprotic protogenic solvents have higher acidic properties, but lower basic ones (always in comparison to water). Examples are formic and acetic acid. Amphiprotic protophilic solvents have lower acidity and higher basicity than water, with formamide or ethanolamine as examples. Aprotic dipolar solvents have low acidity and (occasionally) basicity as well, with A,A-dimethylformamide and dimethylsulfoxide as examples for protophilic dipolar solvents and acetonitrile for a protophobic dipolar solvent. 

Where solubility alone is the issue, simply changing solvent to permit all species to be dissolved allows the chemistry to proceed essentially as it would in aqueous solution were species soluble. Typical molecular organic solvents used in place of water include other protic solvents such as alcohols (e.g. ethanol), and aprotic solvents such as ketones (e.g. acetone), amides (e.g. dimethylformamide), nitriles (e.g. acetonitrile) and sulfoxides (e.g. dimethylsulfoxide). Recently, solvents termed ionic liquids, which are purely ionic material that are liquid at or near room temperature, have been employed for synthesis typically, they consist of a large organic cation and an inorganic anion (e.g. lV, lV,-butyl(methyl)-imidazolium nitrate) and their ionic nature supports dissolution of, particularly, ionic complexes. 

The oxidation of alcohols to carbonyl compounds is one of the most fundamental and important processes in the fine chemical industry. The classical methodology is based on the stoichiometric use of heavy metals, notably Cr and Mn (1,2). Alternatively metal-free oxidation, such as the Swern and Pfitzner-Moffat protocols, is based on e.g., dimethylsulfoxide as oxidant in the presence of an activating reagent such as N,N -dicyclohexylcarbodiimide, an acid anhydride or acid halide (3). Although the latter methods avoid the use of heavy metals, they usually involve moisture-sensitive oxidants and environmentally undesirable reaction media, such as chlorinated solvents. The desired oxidation of alcohols only requires the formal transfer of two hydrogen atoms, and therefore the atom economy of these methods is extremely disadvantageous. The current state of the art in alcohol oxidations... 

The reaction can also be catalyzed by Cu(I) ions supplied by elemental copper, thus further simplifying the experimental procedure-a small piece of copper metal (wire or turning) is all that is added to the reachon mixture, followed by shaking or stirring for 12-48 h [6, 23, 50]. Aqueous alcohols (methanol, ethanol, tert-butanol), tetrahydrofuran, and dimethylsulfoxide can be used as solvents in this procedure. Cu(ll) sulfate may be added to accelerate the reaction however, this is not necessary in most cases, as copper oxides and carbonates, the patina on the metal surface, are sufficient to initiate the catalytic cycle. Although the procedure based on copper metal requires longer reaction times when performed at ambient temperature, it usually provides access to very pure triazole products... 

In vitro formation of a charge transfer complex between chlor-promazine as the electron donor and melanin, derived from squid or human hair as the electron acceptor, was demonstrated by an increase in conductivity in a mixture of solutions of the components of a number of solvents. If triethanolamine or diethylacetamide were used as solvents, this increase was demonstrable by simple mixture of the components but could be further increased by uv irradiation. In other solvents, such as dimethylsulfoxide, significant increases of conductivity were demonstrable only after uv irradiation. 

---