Chemicals dimethylsulfoxide

METHOD 2 Speed chemists have used hydroiodic acid (HI) for years to reduce ephedrine to meth. So when the government placed HI on the restricted list, speed chemists took to making the HI themselves. One of the ways they used was to make Hi in DMSO (dimethylsulfoxide, a common solvent) by reacting Nal or Kl with sulfuric acid. This a standard way to make both HBr or Hi in water (see the Chemicals section of this book) except these speed chemists were using the non-aqueous solvent DMSO instead of water. 

In order to gain information on the environments of certain atoms in dissolved species, in melts or in solids (crystalline or noncrystalline), which are not accessible to diffraction studies for one reason or another, X-ray absorption spectrometry (XAS) can be applied, with the analysis of the X-ray absorption near-edge structure (XANES) and/or the extended X-ray absorption fine structure (EXAFS). Surveys of these methods are available 39,40 a representative study of the solvation of some mercury species, ElgX2, in water and dimethylsulfoxide (DMSO) by EXAFS and XANES, combined with quantum-chemical calculations, has been published.41... 

These include hydrazine, dimethylsulfoxide (DMSO), formamide and some derivatives (N-methylformamide and dimethylformamide), acetamide and some derivatives, and pyridine N-oxide. Some salts such as potassium acetate also intercalate kaolinites. Once intercalated by one of these small molecules or salts, other molecules which normally do not directly intercalate kaolins can be introduced by replacement. Further, the exposure of the inner surfaces by intercalation gives one the opportunity to alter the interlayer bonding of the kaolin layers by chemical modification of the inner surfaces. 

Figure 3.22. Fluorescence titrations of anthrylboronic acid 16 (0.75 jiM) at pH 7.4 (20 mAf phosphate buffer) as a function of polyol concentration (+, fructose , t,l,l-tris(hydroxymethyl)ethane a, glucose +, ethylene glycol). All solutions contain 1% (v/v) dimethylsulfoxide (DMSO). (Reproduced from Ref. 26. Copyright 1992 American Chemical Society.)...

Much of the methyl mercaptan and dimethyl sulfide can be oxidized to dimethylsulfoxide (DMSO), a useful side product that is a common polar, aprotic solvent in the chemical industry. This is in fact the primary method... 

The octet rule is one of the cornerstones of chemical bonding theory. While the vast majority of molecules conform, apparent exceptions occur for molecules incorporating second-row (and heavier) main-group elements. Apparent refers to the fact that molecules such as dimethylsulfoxide and dimethylsulfone may either be represented in terms of structures with ten and twelve valence electrons, respectively, surrounding sulfur, or as zwitterions with the normal complement of eight valence electrons (see also discussions in Chapters 5 and 16). 

Figure 10. Normalized 23Na chemical shifts in some binary solvent mix-tures involving transfer from acetonitrile (49). DMSO = Dimethylsulfoxide HMPT = Hexametnylphosphotriamide TMU = Tetramethylurea MeNC>2 = Nitromethane Py = Pyridine...

Dimethylsulfoxide (DMSO), the archetypal penetration enhancer, is a powerful aprotic solvent that is colorless, odorless, and hygroscopic its value as an enhancer may be predicted from its use chemically as a universal solvent (Figure 12.2). 

Figure 7. Protonated dimethylsulfoxide (DMSO) and calculated 13C NMR chemical shift values.

Immediately upon excitation of an IPCT band with a fs laser at 400 nm, transient absorption was observed for both salts in solutions with a peak at about 600 nm, characteristic of 4,4/-bipyridinium radical cations. Figure 20 shows the transient absorption spectra of PV2+(I )2 in methanol solution. A marked increase in the absorbance of the 4,4/-bipyridinium radical cations took place within 1 ps after excitation. 4,4/-Bipyridinium radical cations were thus formed in a fs time scale by the photoinduced electron transfer from a donor I- to an acceptor 4,4/-bipyridinium upon IPCT excitation [48], The time profiles of transient absorption at 600 nm are shown in Fig. 21 for (a) PV2+(I )2 in a film cast from DME and (b) PV2+(TFPB )2 in DME solutions. Both of them showed a very rapid rise in about 0.3 ps, which was almost the same as the time resolution of our fs Ti sapphire laser measurement system with a regenerative amplifier. Similar extremely rapid formation of 4,4/-bipyridinium radical cations was observed for PV2+(I )2 salts in methanol and dimethylsulfoxide solutions upon IPCT excitation, respectively. These results demonstrated that the charge separated 4,4/-bipyridinium radical cations were formed directly upon IPCT excitation because of the nature of IPCT absorption bands (that the electrons correlated with the IPCT band are transferred partially at the ground state and completely at the excited state). Such a situation is very different from usual photochromism which is caused by various changes of chemical bonds mainly via the excited singlet state. No transient absorption was observed for PV2+(I )2... 

The broad band decoupled carbon-13 NMR spectrum of cimetidine hydrochloride (Figure 3) was obtained by using a solution of approximately 100 mg/ml in deuterated dimethylsulf oxide. The deuterium signal of dimethylsulfoxide was used as the internal reference and the spectrum was obtained on a Varian Associates Model FT-80 fourier transform NMR spectrometer. The chemical shift assignments are ... 

The proton NMR spectrum of indcanethacin in deuterated dimethylsulfoxide (dg DMSO) at a concentration of 20% (w/v) is reproduced in Figure 3. A tabulation of the assignments and chemical shifts is found in Table 1(17). 

Proton magnetic resonance spectra of melphalan in dimethylsulfoxide (DMSO)-dg and D2O—DC1 solutions and of melphalan hydrochloride in DMSO-dg are shown in Figure 4. The spectra were run on a Varian FT-80A spectrometer at 80 MHz. The assignments of the chemical shifts are tabulated in Table I. 

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. 

A high-throughput assay for bacterial RNA polymerase has been successfully developed and validated using a 96-well, automated format [70], The reaction mixture contained a DNA template, nucleotide substrates (NTPs), supplemented with a-33P-labeled CTP in Tris-acetate buffer (pH 6.8). The polymerase reaction was carried out at 34°C for 40 min (providing linear kinetics). The effect of dimethylsulfoxide (DMSO), the usual solvent for test compounds used in a screen, was taken into consideration. The radiolabeled RNA transcripts were allowed to bind diethyl aminoethyl (DEAE) beads, which were then separated via filtration, and radioactivity associated with the wells was quantitated to measure the RNA polymerase activity. The standard deviation of the measured activity was typically < 15% of the average. Use of this assay to screen for RNA polymerase inhibitors from chemical libraries and natural products led to the identification of DNA intercalators (known to inhibit RNA polymerase activity), rifampicin (a known inhibitors of RNA polymerase), and several derivatives of rifampicin from Actinomycetes extracts. Therefore this assay can be reliably utilized to detect novel inhibitors of bacterial RNA polymerase. 

In the fourth chapter, Thomas Rosenau, Antje Potthast, and Paul Kosma describe current investigations on reactive intermediates and reaction mechanisms in cellulose chemistry. The chemical modification and regeneration of cellulose requires its activation and/or dissolution in media like sodium lye, N-mclhybnorpholine-N-oxide (NMMO), N, N-dimethylacetamide (DMAc), or in carbanilation mixtures containing dimethylsulfoxide (DMSO). In these media - very important for research and large-scale processes - the trapping and characterization of the intermediates has been carried out. 

The toxicity tests were conducted by exposing the organisms to solutions of at least five concentrations with a number of variable replicates from test to test. Single chemicals of high purity were initially dissolved in dimethylsulfoxide (DMSO) not exceeding the concentration of 0.01% (v/v) in the test solution.15,12... 

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