Dimethyl sulfoxide, purification

While water has been used as a solvent more than any other media, nonaqueous solvents [e.g., acetonitrile, propylene carbonate, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or methanol] have also frequently been used. Mixed solvents may also be considered for certain applications. Double-distilled water is adequate for most work in aqueous media. Triple-distilled water is often required when trace (stripping) analysis is concerned. Organic solvents often require drying or purification procedures. These and other solvent-related considerations have been reviewed by Mann (3). 

A mixture of silver nitrate and dimethyl sulfoxide is stirred vigorously for co. 1 hour to dissolve all of the salt. Reagent-grade dimethyl sulfoxide was used without purification. 

N-Bromosuccinimide purchased from Arapahoe Chemical Company was used without purification. If the purity of the N-bromosuccinimide is in doubt, it should be titrated before use by the standard iodide-thiosulfate method and purified, if necessary, by recrystallization from 10 times its weight of water. Solutions of N-bromosuccinimide in dimethyl sulfoxide cannot be stored, since the solvent is oxidized by the brominating reagent. 

Wan J, TK Tokunaga, E Brodie, Z Wang, Z Zheng, D Herman, TC Hazen, MK Firestone, SR Sutton (2005) Reoxidation of bioreduced uranium under reducing conditions. Environ Sci Technol 39 6162-6169. Weiner JH, DP Macisaac, RE Bishop, PT Bilous (1988) Purification and properties of Escherichia coli dimethyl sulfoxide reductase, an iron-sulfur molybdoenzyme with broad substrate specificity J Bacterial 170 1505-1510. 

The parent hexathiaadamantane (185) is obtained preparatively when a solution of formic acid and hydrochloric acid in nitrobenzene is allowed to stand for several weeks in a hydrogen sulfide atmosphere the product which separated is almost insoluble in all common solvents and purification presents a problem. Only large volumes of dimethyl sulfoxide at reflux serve for recrystallization.224 The reaction of thioacetic acid with formic acid in the presence of zinc chloride gives tetramethyl-(186), monomethyl-, dimethyl-and trimethylhexathiaadamantane derivatives (187).225 Other variations include the reaction of thioacetic acid with a /i-diketone,226 and the use of boron trifluoride227 or aluminum chloride as a catalyst.228... 

Materials. Reagent grade solvents, dimethyl formamide (DMF), dimethyl acetamide (DMAC), dimethyl sulfoxide (DMSO) and methanol were purchased from Baker, stored over molecular sieves once opened, and used without further purification. Aminoethane thiosulfuric acid (AETSA) purchased from Kodak, and Taurine, purchased from Alfa were purified by recrystallization. Each was thrice recrystallized from hot, deionized water. The crystalline precipitate was dried (48 hours at 40 °C) in-vacuo and subsequently stored in a desiccator. Benzophenone (BP) was purchased from Aldrich Chemical Company. QUANTACURE BTC (BTC), (4-benzolybenzyl) trimethylammonium chloride, was used as supplied by Aceto, Inc., Flushing, New York. Phenyl glycidyl ether (PGE) was purchased from MCB, distilled in-vacuo. and stored at -15 °C. Epon 828 was used as supplied bv Shell Chemical Company. The epoxy equivalent weight (EEW) for Epon 828 determined by an appropriate titration, was found to be 187.7. 

DMSO (dimethyl sulfoxide) (99.8%) stored in an Aldrich Sure/Seal bottle was purchased from Aldrich Chemical Company, Inc., and used without further purification. 

The distilled product is similar in purity to the crude material. A small amount of dimethyl sulfoxide and minor impurities remain. Purification of the crude product by flash chromatography (1 1 ether/hexanes) affords 6,6-dimethoxyhexanal that is pure by and 13C NMR in 90-95% yield. 

Dimethyl sulfoxide (DMSO) [14] Commercial products contain water and small amounts of dimethyl sulfide and dimethyl sulfone as impurities. In the purification, molecular sieve 5A (activated at 500 °C under argon for 16 h) is added and kept for several days to reduce water to < 10 ppm and other low boiling point impurities to < 50 ppm. Then the solvent is filtered and the filtrate is distilled over CaH2 at reduced pressure in a nitrogen atmosphere. 

Chemicals and Standard Solutions. Cyclohexanone, cyclohexanol, 1,3,5-trichlorobenzene, 1,2,4-trichlorobenzene, phenol, 4-methylphenol, 4-chloro-phenol, 1,2,3,4-tetrahydroisoquinoline, 1-chlorohexane, 1-chlorododecane, and 1-chlorooctadecane were obtained from Aldrich. Acetone, tetrahydrofuran, ethyl acetate, toluene, dimethyl sulfoxide, and methanol were obtained from J. T. Baker. Distilled-in-glass isooctane, methylene chloride, ethyl ether, and pentane were obtained from Burdick and Jackson. Analytical standard kits from Analabs provided methyl ethyl ketone, isopropyl alcohol, ethanol, methyl isobutyl ketone, tetrachloroethylene, dodecane, dimethylformamide, 1,2-dichlorobenzene, 1-octanol, nitrobenzene, 2,4-dichlorophenol, and 2,5-dichlorophenol. All chemicals obtained from the vendors were of the highest purity available and were used without further purification. High-purity water... 

The solubility of NHDC in hot water, alcohol, aqueous alkali, acetonitrile, dimethyl sulfoxide, and alcohol/water mixture facilitates its selective extraction from food samples (20,91,94). It is extracted from jams, fruit juices, and dairy products with methanol (66,93) or acetone (95) and filtered or centrifuged. Chewing gum samples are dissolved in chloroform and extracted with water. The extract is centrifuged, and the clear supernatant is injected into the HPLC (95). If necessary, sample cleanup and concentration may be achieved by selective adsorption or desorption (20) on Sep-Pak Cl8 (96). Tomas-Barberan et al. (93) used Amberlite XAD-2 resin for purification of jam extract. Sugars, pectin, and other polar compounds were eluted with water, and NHDC was eluted with methanol. After concentration, the extract was further purified on a Sephadex LH-20 column prior to HPLC analysis. 

A different semisynthetic method involves the acylation of an amino alcohol with a peptide ester and the resulting amino alcohol is subsequently oxidized to the aldehyde 40 The acylation of H-Phe[CH2OH] with the peptide ester Z-Ala-Ala-Leu-OMe is carried out in 5% DMF/MeCN with the subtilisin distributed on the surface of macroporous silica gel. The resulting peptide alcohol is oxidized under mild conditions using anhydrous dimethyl sulfoxide and 20-fold excess of acetic anhydride with purification via flash chromatography 40] Z-Phe[CH2OH] has been oxidized under these conditions and the optical rotation indicates little epimerization as compared to literature values 11 40 ... 

Dimethyl sulfoxide, Fisher Scientific Company, was used without further purification. 

A number of companies supply reagent or spectroquality solvents that have been purified to remove UV-absorbing impurities. Some of them, particularly dimethyl sulfoxide, may be suitable for general electrochemical use as purchased. However, small quantities of electroactive impurities (particularly water) often are present in spectroquality solvents. Therefore, a particular batch of solvent always should be tested by measurement of the residual current with an appropriate supporting electrolyte and a platinum, gold, or carbon electrode (to test the anodic limits) and a platinum electrode (to test the cathodic limits). The voltage window or domain of electroactivity is a sensitive measure of the adequacy of the purification procedures. 

Although a number of solvents have been used by different workers, only a few enjoy continued favor. In Table 7.11 the physical properties of more than 50 solvents are listed (not all of them are aptotic). In the following paragraphs some of the properties and purification methods for four solvents are discussed acetonitrile, propylene carbonate (PC), dimethylformamide (DMF), and dimethyl sulfoxide (Me2SO). These are the most widely used solvents and prob-... 

Although somewhat difficult to purify, acetonitrile is stable on storage after purification. It is toxic, with a maximum recommended limit of 40 ppm,79 and the vapor pressure is sufficient for this to be a hazard. Its high volatility makes the removal of solvent by evaporation easy (e.g., workup of a reaction mixture for product identification). Both radical cations and anions react with traces of wate r in acetonitrile, and, because it does not hydrogen-bond to water as do dimethyl sulfoxide and dimethylformamide, radical anions generally have a... 

The reagent-grade solvent generally contains few impurities beyond traces of water and can be used without further purification for many electrochemical purposes. For some applications the presence of traces of water can significantly affect the properties of the solvent. For example, dimethyl sulfoxide and dimethylformamide that contain 100 ppm of water dissolve NaCN and NaN3 to... 

The bromohydrin is then quantitatively converted to the THP ether, which is added to LiC=CH-ethylenediamine complex in dimethyl sulfoxide to give VII in very high yield. No purification is required in either of these steps. A shorter synthesis of 9-decyn-l-ol (IX) was subsequently developed. An acetylene "zipper" isomerization (42) with sodio-1,3-diaminopropane is used to convert either 3-decyn-l-ol (VIII) or 2-decyn-l-ol into the terminal alkynol IX. Both of these starting alkynols are commercially available and the saving in labor is advantageous for moderate scale production. 

J. F. Coetzee (ed.) Recommended Methods for the Purification of Solvents and Tests for Impurities, Pergamon Press, Oxford, 1982. (Acetonitrile, Sulfolane, Propylene carbonate. Dimethyl sulfoxide, V,7V-Dimethylformamide, Hexamethylphosphoric tiiamide. Pyridine, 1,2-Diaminoethane, N-Methylacetamide, and V-Methylpropionamide). 

McEwan, A. G., Ferguson, S. J., and Jackson, J. B., 1991, Purification and properties of dimethyl-sulfoxide reductase from Rhodobacter capsulatus, Biochem. J. 274 3059307. 

A fluorodensitometric assay was developed by Montague and co-workers 140) to analyze cultures from Ochrosia elliptica for ellipticine (1), 9-methoxy-ellipticine (2), and 9-hydroxyellipticine (3) by thin-layer chromatography (TLC) without the need for prior purification. Using silica gel impregnated with dimethyl sulfoxide and a mobile phase of EtOAc-water-l-octanol (17 2 2), these workers were able to achieve good separation of these alkaloids and to assay the resulting chromatograms by fluorodensitometry (40-300 fmol detection limits of alkaloid). 

One of the simplest ways to form disulfide bonds is oxidation of the fully deprotected linear peptide obtained after cleavage from the resin (in some cases, disulfide bridges began to form during the cleavage step) before or after preparative HPLC purification. The cyclization has to be performed using high dilution conditions to promote intramolecular disulfide bond formation versus inter-molecular dimerization. Dimethyl sulfoxide is used to accelerate the oxidation reaction (35). 

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