Dimethyl sulfoxide, determination

Extraction Solvent. Dimethyl sulfoxide is immiscible with alkanes but is a good solvent for most unsaturated and polar compounds. Thus, it can be used to separate olefins from paraffins (93). It is used in the Institute Fransais du Pntrole (IFF) process for extracting aromatic hydrocarbons from refinery streams (94). It is also used in the analytical procedure for determining polynuclear hydrocarbons in food additives (qv) of petroleum origin (95). 

Water plays a crucial role in the inclusion process. Although cyclodextrin does form inclusion complexes in such nonaqueous solvents as dimethyl sulfoxide, the binding is very weak compared with that in water 13 Recently, it has been shown that the thermodynamic stabilities of some inclusion complexes in aqueous solutions decrease markedly with the addition of dimethyl sulfoxide to the solutions 14,15>. Kinetic parameters determined for inclusion reactions also revealed that the rate-determining step of the reactions is the breakdown of the water structure around a substrate molecule and/or within the cyclodextrin cavity 16,17). 

FIGURE 2. The molecular model of dimethyl sulfoxide. The following C—H lengths (A), S—C—H bond angles (deg) and x(C—S—C—H) torsional angles (deg) were determined from microwave spectra by Typke17 ... 

In this study, the absorption rates of carbon dioxide into the solution of GMA and Aliquat 336 in such organic solvents as toluene, N-methyl-2-pirrolidinone(NMP), and dimethyl sulfoxide(DMSO) was measured to determine the pseudo-first-order reaction constant, which was used to obtain the elementary reaction rate constants. 

Glycosyl-linkages were determined by GC-EIMS of the partially methylated alditol acetates. RG-II samples (2 mg) were methylated using sodium methyl sulfmyl carbanion and methyl iodide in dimethyl sulfoxide [24] followed by reduction of the uronosyl groups with lithium triethylborodeuteride (Superdeuteride , Aldrich) [23,25]. Methylated and carboxyl-reduced samples were then submitted to acid hydrolysis, NaBIlt reduction and acetylation, partially methylated alditol acetates being analysed by EIMS on two fused-silica capillary columns (DB-1 and DB-225) [20]. 

Kemp and coworkers employed the pulse radiolysis technique to study the radiolysis of liquid dimethyl sulfoxide (DMSO) with several amines as solutes [triphenylamine, and N, A, A, N -tetramethyl-p-phenylenediamine (TMPD)]. The radiolysis led to the formation of transient, intense absorptions closely resembling those of the corresponding amine radical cations. Pulse radiolysis studies determine only the product Ge, where G is the radiolytic yield and e is the molar absorption. Michaelis and coworkers measured e for TMPD as 1.19 X 10 m s and from this a G value of 1.7 is obtained for TMPD in DMSO. The insensitivity of the yield to the addition of electron scavenger (N2O) and excited triplet state scavenger (naphthalene) proved that this absorption spectrum belonged to the cation. 

The most stable structures and formation energies of zinc thiocyanate complexes have been calculated by ab initio density functional methods. The formation energies of the linkage isomers [Zn(NCS)4]2. [Zn(NCS)2(SCN)2]2, and [Zn(SCK)4]2 were determined. A comparison of the formation energies indicated that [Zn(SCN)4]2 is the most stable isomer both in water and in dimethyl sulfoxide.567... 

Pure dimethyltriazanium chloride decomposes at 133 to 134° (the checker reports 135 to 136°). The salt is very hygroscopic and should be stored in a desiccator. It is readily soluble in water, methanol, ethanol, and dimethyl sulfoxide. An aqueous solution is stable at room temperature. Free iodine is liberated from an acidic iodide solution, and this reaction makes it possible to determine the triazanium content.3... 

Dissolve NHS-PEGg-maleimide (MW 601.6) into dimethyl sulfoxide (DMSO) at a concentration of 20 mM. PEG-type crosslinkers often exist as a thick oily mass, and preparing the solution may involve dissolving an entire vial of the compound into DMSO to determine accurately the required concentration. 

Hong and coworkers have investigated the cycloaddition chemistry of fulvenes with a wide variety of alkenes and alkynes in great detail [191]. As one example, the reaction of 6,6-dimethylfulvene with benzoquinone is shown in Scheme 6.92. Under microwave conditions in dimethyl sulfoxide (DMSO) at 120 °C, an unusual hetero-[2+3] adduct was formed in 60% yield, the structure of which was determined by X-ray crystallography. The adduct is a structural analogue of the natural products aplysin and pannellin and differs completely from the reported thermal (benzene, 80 °C) Diels-Alder cycloaddition product of the fulvene and benzoquinone (Scheme 6.92) [191]. 

Bajoras and Makuska investigated the effect of hydrogen bonding complexes on the reactivities of (meth)acrylic and isotonic acids in a binary mixture of dimethyl sulfoxide and water using IR spectroscopy (Bajoras and Makuska, 1986). They demonstrated that by altering the solvent composition it was possible to carry out copolymerization in the azeotropic which resulted in the production of homogeneous copolymers of definite compositions at high conversions. Furthermore, it was shown that water solvent fraction determines the rate of copolymerization and the reactivity ratios of the comonomers. This in turn determines the copolymer composition. 

Sulphate has been determined in seawater by photometric titration with hydrochloric acid in dimethyl sulfoxide [223]. The sample (5 ml) is slowly added to dimethyl sulfoxide (230 ml) and titrated with 0.02 M hydrochloric acid (standardised against sulfate) with bromo-cresol green as indicator. Since borate, carbonate, and bicarbonate interfere, a separate determination of alkalinity is necessary. 

Andreae [324,325] has described a gas chromatographic method for the determination of nanogram quantities of dimethyl sulfoxide in natural waters, seawater, and phytoplankton culture waters. The method uses chemical reduction with sodium borohydride to dimethyl sulfide, which is then determined gas-chromatographically using a flame photometric detector. 

Kim and Okamoto carried out studies on a tautomeric equilibrium between a hydrazono and azo derivative, 46 and 47 respectively, by means of NMR spectroscopy (Scheme 3) <1994JHC233>. The 13C and H NMR values could be well assigned to the particular carbon and hydrogen atoms. The equilibria were determined in dimethyl sulfoxide (DMSO) and aqueous trifluoroacetic acid. 

Structure elucidation of three related derivatives of ring system 2 ( temozolomide 9a, mitozolomide 9b, and the related acid derivative 9c) has been carried out by 13C and 15N NMR spectroscopy <1995J(P1)249> (Scheme 2). The 1SN NMR chemical shifts measured in dimethyl sulfoxide (DMSO) solutions are listed in Table 1. For compound 9a, Lowdin charges of the nitrogen atoms have also been calculated and found to have a linear relationship with the experimentally determined chemical shifts of these atoms. The NMR data of 9a have been correlated with those of a series of heterocycles of related structure by the same team <2002MRC300>. 

The molecular structure of dimethyl sulfoxide has been determined both in the gas phase and in the solid state (Table II). The bond angles suggest that the molecule is approximately pyramidal, with sulfur at the apex. The distortions from the expected pyramidal bond angles are... 

The use of both 8(CH3) values and iftM- H) magnitudes does, however, allow determination of the coordination mode in many instances (e.g., 462). Problems due to ligand dissociation are frequently evident in H-NMR studies of sulfoxide complexes. Thus the dimethyl sulfoxide adduct of niobium oxychloride (409) undergoes solvolysis in acetoni-... 

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. 

The exact p R+ value for 20+ could also not be determined by the earlier method. Therefore, dimethyl sulfoxide (DMSO)-water-tetramethylammonium hydroxide (0.011 M) system was used for the measurement. The H scale (Hammett acidity scale) for the system ranges from 12 in water up to 26.2 in... 

In contrast, other authors have preferred to synthesise the individual metabolites for a more confident determination (see Fig. 4.2.1). Table 4.2.1 shows the methods described in the literature to synthesise the non-commercial metabolites of NPEO. Thus, NPEOi and NPEO2 can be synthesised, according to Shang et al. [14], by reacting nonylphenol (NP) with 2-chloroethanol and 2-(2-chloroethoxy) ethanol in the presence of potassium hydroxide and dimethyl sulfoxide. These compounds... 

The cells are permitted to "plant" to the ECM and adjust to the incubator temperature (37°C) and C02 concentration. Then test compounds or controls (both in 0.1% dimethyl sulfoxide, DMSO) are added to the test wells. The cells are then incubated overnight, and the indicator dye Alamar blue10 is added. This noncytotoxic dye reacts to mitochondrial redox reactions and is measured fluorometrically. Cell metabolic activity is determined starting at 3 h after the dye is added and daily thereafter. 

Tse, G., Orbey, H., and Sandler, S.I. Infinite dilution activity coefficients and Henry s law coefficients of some priority water pollutants determined by a relative gas chromatographic method, Environ. Sci Tecbnol, 25(10) 2017-2022, 1992. Tsierkezos, N.G., Kelarakis, A.E., and Palaiologou, M.M. Densities, viscosities, refractive indices, and surface tensions of dimethyl sulfoxide + butyl acetate mixtures at (293.15, 303.15, and 313.15) K, /. Chem. Eng. Data, 45(2) 395-398, 2000. Tsierkezos, N.G. and Molinou, I.E. Densities and viscosities of ethylene glycol mixtures at 293.15 K, /. Chem. Eng. Data, 44(5) 955-958, 1999. 

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