Dimethyl sulfoxide solution

Isotope labeling by derivative formation with deuterated reagents is useful for the preparation of analogs such as dg-acetonides, da-acetates, da-methyl ethers, dg-methyl esters, etc. The required reagents are either commercially available or can be easily prepared. (The preparation of da-methyl iodide is described in section IX-F. Various procedures are reported in the literature for the preparation of dg-acetone, da-diazometh-ane57.i63.i73 and da-acetyl chloride. ) These reactions can be carried out under the usual conditions and they need no further discussion. A convenient procedure has been reported for the da-methylation of sterically hindered or hydrogen bonded phenolic hydroxyl functions by using da-methyl iodide and sodium hydroxide in dimethyl sulfoxide solution. This procedure should be equally applicable to the preparation of estradiol da-methyl ether derivatives. 

An alternate ethynylating reagent is the lithium acetylide-ethylene-diamine complex which is available commercially. This reagent in dimethyl sulfoxide solution has been used to ethynylate 11 j -hydroxyestrone and its 3-methyl ether. 

Bordwell and coworkers63 87 have studied the reaction of 9-fluorenyl carbanions (9-RFP) with a series of electron acceptors and in particular a-halosulfones and sulfoxides, in dimethyl sulfoxide solution. The overall reaction is characterized by the formation of the 9,9 -bis-fluorenyl derivative and the reduction of the halogenated acceptor. A family of 9-substituted fluorenyl carbanions covering a basicity range of 9.1 pKa units was used and... 

Henriquez R, Gomez H, Riveros G, Guillemoles JF, Froment M, Lincot D (2004) Electrochemical deposition of ZnSe from dimethyl sulfoxide solution and characterization of epitaxial growth. J Phys Chem B 108 13191-13199... 

Elbaum R, Vega S, Hodes G (2001) Preparation and surface structure of nanocrystalline cadmium sulfide (sulfoselenide) precipitated from dimethyl sulfoxide solutions. Chem Mater 13(7) 2272-2280... 

Tomas et al. [281] have calculated the tautomeric equilibrium of 1,2,3-benzotriazole in the gas phase and compared their results to experimental data [282] derived from ultraviolet spectroscopy. Experiment suggests that 35 is about 4 kcal/mol more stable than 34 this result is consistent with calculations [281] at the MP2/6-31G level, which predict 35 to be 2.5 kcal/mol more stable than 34. The same level of theory predicts 33 to be 5.0 kcal/mol more stable than 32 in the parent triazole system. Although experimental data are available indicating 35 to be the dominant tautomer in CDCf and d6-dimethyl sulfoxide solutions [279, 283], this equilibrium does not appear to have been the subject of any modeling, continuum or otherwise. It may prove to be somewhat challenging, however. Tomas et al. point out that correlation effects favor 35 by about 5 kcal/mol at the MP2 level AMI, PM3, and HF calculations with moderate basis sets all predict... 

F. G. Bordwell. Equilibrium Acidities in Dimethyl Sulfoxide Solution. Acc. Chem. Res. 1988,21, 456-A63. 

Receptor [86] (Fig. 44) forms extremely stable 1 1 anion complexes with chloride, bromide and H2PC>4 in dimethyl sulfoxide solutions and with the adipate anion in acetone solutions. Interestingly, this receptor displays selectivity for chloride over dihydrogenphosphate. 

Recently it has been observed in this laboratory and others (60-63) that this reaction can be run under homogeneous conditions in dimethyl sulfoxide solution to obtain the desired modified polymers. These modified polymers would have several potential uses and exhibit some unusual properties. 

The coordination polymer [Zn(tmbdc)(dmso)2]-2(DMSO) (tmbdc = 2,3,5,6-tetramethyl-l,4-benzenedicarboxylate) has been synthesized by layer diffusion in DMSO (dimethyl sulfoxide) solution. The compound contains ID chain formed by octahedraly coordinated Zn ion chelated by the carboxyl groups of tmbdc. In another recently reported coordination polymer [Zn2(bdc)2(dmso)2]-5(DMSO) (bdc = 1,4-... 

The catalysts having the initial form of Co(acac)3 were recovered after the decomposition of peracrylic acid in benzene and dimethyl sulfoxide solution the catalyst recovered from benzene (catalyst B) could hardly be separated from the polymers, indicating a chemical bond between the catalyst and polymers. On the other hand, the catalyst from... 

Figure 7. First derivative ESR spectra of radical anions observed in dimethyl sulfoxide solutions of potassium tert-butoxide. Top, autoxidation product of diphenylamine. No signal was observed in the absence of oxygen. Middle, autoxidation of 4-hydroxy-diphenylamine. Bottom, spontaneous reduction product of mono-anil of p-benzoquinone.

McDermot, H.L., Murray, G.W., Heggie, R.M. 1965. Penetration of guinea pig and rabbit skin by dimethyl sulfoxide solutions of a quaternary oxime. Canad. J. Physiol. Pharmacol. 43 845-848. 

Our alternative approach has been to synthesize the solvento intermediate and then study its reactions in isolation. We thereby hope to show that its reactivity and steric course is inconsistent with the postulate stating that it is an intermediate in the substitution reactions. Complexes of the type cis- and trans-[Co en2 CH3OH q]+2 (7)f and cis-[Co en2 (CH3)2SO Cl]+2 32) have been prepared. We have shown in the first case that the lability of the coordinated methanol does not sufficiently explain the nonappearance of the solvento complex in the reactions of cis- and trans-[Co en2 Cb]"1" in methanol unless it is not an intermediate in the reaction. In dimethyl sulfoxide solution, cis- and trans-[Co en2 Cb] have been shown to isom-erize to an equilibrium mixture that also contains the solvento intermediate 32). 

Killday etal. (1988) also provided evidence for internal autoreduction of ferric nitrosyl heme complexes, as previously proposed by Giddings (1977). Heating of chlorohemin( iron-III) dimethyl ester in dimethyl sulfoxide solution with imidazole and NO produced a product with an infrared spectra identical to that of nitrosyl iron(ll) protoporphyrin dimethyl ester prepared by dithionite reduction. Both spectra clearly showed the characteristic nitrosyl stretch at 1663 and 1665 cm. They thus proposed a mechanism for formation of cured meat pigment which includes internal autoreduction of NOMMb via globin imidazole residues. A second mole of nitrite is proposed to bind to the heat-denatured protein, possibly at a charged histidine residue generated in the previous autoreduction step. 

These complexes, unlike the crown ether complexes but similar to the aza-crown and phthalocyanine complexes, are fairly stable in water. Their dissociation kinetics have been studied and not surprisingly they showed marked acid catalysis.504 Association constant values for lanthanide cryptates have been determined.505,506 A study in dimethyl sulfoxide solution by visible spectroscopy using murexide as a lanthanide indicator showed that there was little lanthanide specificity (but surprisingly the K values for Yb are higher than those of the other lanthanides). The values are set out in Table 9.507... 

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... 

For instance Shugar and Fox106 have shown that the spectrum of cytosine resembles that of 1-methylcytosine (form 2), not that of 2-methoxycytosine (form 1). Similarly, Kenner et al.100 have established that lactam-imine forms 6 were unimportant both for 1-methylcytosine (thus also for cytosine itself) and for its aminoacetyl derivatives. Katritzky and Waring60 have extended these studies and in particular showed that tautomers 3 and zwitterionic structures 10 were unimportant in the tautomeric equilibrium in both aqueous and dimethyl sulfoxide solutions. Although these last comparisons were made with only two partially methylated cytosines still capable of tautomerism, the reported conclusions agree with those reached later by Brown and Lyall96 on much wider evidence. 

Other low-temperature studies have been motivated by the desire to characterize and understand processes occurring in unusual media. For example, the use of liquid ammonia [8-10] and liquid sulfur dioxide [11-13] naturally requires reduced temperatures unless high pressures are used, as is done for electrochemistry in supercritical fluids [14]. Frozen media are interesting systems in terms of mass transport phenomena and microstructural effects. Examples include glasses of acetonitrile and acetone [15], frozen dimethyl sulfoxide solutions [16,17], and the solid electrolyte HC104 5.5 H20 [18-20]. 

Fig. 1.40. Volume changes of oocytes of rhesus monkeys as a function of the time elapsed after their exposure to 10% dimethyl sulfoxide solution (Figure 6 from [1.28])...

The proton magnetic resonance spectrum (Figure 4) of cimetidine was recorded for a deuterated dimethyl sulfoxide solution containing approximately 100 mg/ml of the compound with tetramethylsilane as the internal standard. The spectrum illustrated was obtained using a Perkin-EImer R32 proton magnetic resonance (CW) spectrometer. The resonances are ... 

An ab initio study of the. S N2 and E2 mechanisms has been performed for the reaction between the cyanide ion and ethyl chloride in dimethyl sulfoxide solution.5 Theoretical calculations have predicted a free energy barrier for nitrile formation of 24.1 kcal mol-1, close to the experimental value of 22.6 kcal mol-1 (Scheme 3). It has also been predicted that the isonitrile formation is less favorable by 4.7 kcal mol-1, while the elimination mechanism is less favorable by more than 10 kcal mol-1. These results indicated that isonitrile formation and bimolecular elimination are not significant side-reactions for primary alkyl chloride reactions. 

---