Das Lösungsmittel Dimethylsulfoxid

Martin, Dieter; Weise, Alfons; Niclas, H.‐J.

doi:10.1002/ange.19670790803

Cited by 81 publications

(11 citation statements)

References 172 publications

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“…Dimethylsulfoxide (DMSO) is a common solvent in chemical laboratories, [8][9][10][11] even though industry tries to avoid it. It is widely used in laboratories due to its ability to dissolve a wide range of chemical compounds (from ionic inorganic salts to purely covalent compounds), because it is an aprotic but highly polar polyfunctional molecule with both a hydrophobic and a hydrophilic site.…”

Section: Introductionmentioning

confidence: 99%

Ligand‐Exchange Processes on Solvated Lithium Cations: DMSO and Water/DMSO Mixtures

et al. 2007

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Solutions of LiClO(4) in solvent mixtures consisting of dimethylsulfoxide (DMSO) and water, or DMSO and gamma-butyrolactone, were studied by (7)Li NMR spectroscopy (for complexation by cryptands in gamma-butyrolactone as a solvent, see: E. Pasgreta, R. Puchta, M. Galle, N. J. R. van Eikema Hommes, A. Zahl, R. van Eldik, J. Incl. Phen., 2007, 58, 81-88). Chemical shifts indicate that the Li(+) ion is coordinated by four DMSO molecules. In the binary solvent mixture of water and DMSO, no selective solvation is detected, thus indicating that on increasing the water content of the solvent mixture, DMSO is gradually displaced by water in the coordination sphere of Li(+). The ligand-exchange mechanism of Li(+) ions solvated by DMSO and water/DMSO mixtures was studied using DFT calculations. Ligand exchange on [Li(DMSO)(4)](+) was found to follow a limiting associative (A) mechanism. The displacement of coordinated H(2)O by DMSO in [Li(H(2)O)(4)](+) follows an associative interchange mechanism. The suggested mechanisms are discussed in reference to available experimental and theoretical data.

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Section: Introductionmentioning

confidence: 99%

Ligand‐Exchange Processes on Solvated Lithium Cations: DMSO and Water/DMSO Mixtures

et al. 2007

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“…On addition of D 2 0 the singlet of an amide or imide proton at 9.9 ppm5) and the doublets of three secondary hydroxyl groups disappear. One of these doublets (6.12 ppm, J = 7 Hz, HO-C (9)) forms an AB-system with another doublet at 4.41 pprn ( J = 7 Hz, H-C (9)). By spin-spin decoupling experiments all signals of the side chain from C (10) to C (1 5) could be assigned.…”

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confidence: 99%

Isolation and Structure of Pseurotin A, a Microbial Metabolite of Pseudeurotium ovalis STOLK with an Unusual Heterospirocyclic System

Bloch

Tamm

1981

Helvetica Chimica Acta

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The structure and absolute configuration of pseurotin A, a new metabolite, isolated from culture filtrates of Pseudeurotium ovalis STOLK (Ascomycetes) has been shown to be (1'S,2'S, 5 S, 8 S. 9 R, 3'Z)-8-benzoyl-2 (l', 2-dihydroxy-3'-hexenyl)-9hydroxy-8-methoxy-3-methyl-1 -oxa-7-azaspiro (4.41non-2-ene-4.6-dione (1). 1.Introduction. -In 1968 Sigg et al. [ l ] isolated ovalicin from cultures of Pseudeurotium ovalis STOLK (Ascomycetes) as main metabolite and determined its structure. The biosynthesis [2] and the immuno-suppressive activity [3] of the new compound were studied. As reported in preliminary communications, we have found a second minor metabolite in the cultures of the same organism, named pseurotin A*). Its structure 1 was elucidated by spectral data and chemical transformations [4], and by X-ray analysis of its dibromo derivative 2 [5]. In this paper the details of this investigation are presented3). Spectral Data and Chemical Transformations of 1. -Pseurotin A (1) wasisolated from the culture broth of Pseudeurotium ovalis (strain S2269/F) by extraction with ethylene chloride. After final purification of the crude extracts by column chromatography on silica gel, the new metabolite was obtained from dichloromethane/hexane as colourless rhombic crystals of m.p. 162-163.5 and [ u ] g = -5+ 1" (c=0.5, methanol). The yield was ca. 30-35 mg/liter culture broth.Pseurotin A (I), a neutral substance, is readily soluble in polar solvents but much less soluble in non-polar solvents. Heating of solutions during a longer period of time caused decomposition of the compound. The molecular formula, C2*H2,NO,, was deduced from elemental analyses. In the mass spectrum the molecular ion is not observed. The highest peak at mlz 399 (M' -32) is due to the loss of methanol, as it is frequently observed with methyl ethers (especially with a-methoxy ketones) and methyl esters [6a] [6b]. The difference in mass of 32 I ) 2, 3,

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“…It is well knoivn that Hofmann elimillations are not prone to rearrangement. In a recent summarizing article it was pointed out that eliminations of halides and sulfonates with potassium tertiary butoxide in DMSO follow (in cases unlike ours, where there is a choice) the Hofinann rule rather than the Zajcev rule and thus, in this respect, resemble Hofmann eliminations (8). The lack of rearrangement found by us and the special directional behavior of this type of sulfonate elin-rinations might well have a comnlon cause and be due to the nature of the transition state of this reaction.…”

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confidence: 58%