Beware of proteins in DMSO

Dimethylhydrazone (DMH's) 6–10 von enolisierbaren Aldehyden und Ketonen konnen mit n-Butyllithium und/oder Lithium-diisopropylamid in Tetrahydrofuran quantitativ in α-Stellung metalliert werden. Die so erhaltenen Lithiumderivate 11–14 sind hochreaktive Kohlenstoffnucleophile. Ihre Verwendung als Enolataquivalente wird uber die Sequenz Carbonylverbindung, DMH-Derivat. Metallierung, Reaktion mit Alkylhalogeniden (→ 16, 18, 19) und Spaltung zur α-substituierten Carbonylverbindung (17) an einer Anzahl von Beispielen demonstriert. Die Alkylierungen erfolgen, von Spezialfallen abgesehen, regiospezifisch am weniger substituierten Kohlenstoffatom. Cyclohexanonderivate werden stereoselektiv axial alkyliert, was zur Darstellung von trans-disubstituierten Cyclohexanonen ausgenutzt wird. Zur quantitativen Spaltung der Dimethylhydrazone zuruck zu den Carbonylverbindungen unter milden Bedingungen (pH 7, Raumtemperatur) wurde eine neue oxidative Hydrolyse entwickelt. Die Vorteile der Methode werden kurz diskutiert.

Herstellung und synthetische Verwendung von metallierten Dimethylhydrazonen Regio‐ und stereoselektive Alkylierung von Carbonylverbindungen

The vibrational spectrum of ethanol monomer trapped in argon and nitrogen matrices has been recorded in various conditions of temperature and irradiation. The structures and vibrational properties ...

Rotational isomerism of ethanol and matrix isolation infrared spectroscopy

: Raman spectroscopy is used to probe the CN stretching frequency of acetonitrile as a function of concentration in water. The CN band is modeled as the sum of two Gaussians. The concentration dependence of area and width for each of the Gaussian components provides experimental support of an equilibrium between two forms of acetonitrile in solution. In addition, the concentration dependence of each of the bands correlates well with the thermodynamically related Kirkwood-Buff integrals. The frequency shift of the CN band exhibits a linear dependence on the dielectric constant of protic solvents. There has been considerable effort to define and understand the fundamental molecular interactions important in liquid chromatography . Although the solvophobic theory is commonly invoked to explain retention in reversed-phase liquid chromatography (RPLC), recent studies have pointed out shortcomings in this model.

Raman spectroscopic study of solvation structure in acetonitrile/water mixtures

A highly stereoselective synthesis of 3,4-dihydro-1(2H)-isoquinolinones and 8-oxoberbines from homophthalic anhydrides and azomethines

Correlation between the stereochemistry of quinolizidine alkaloids and their infrared spectra from 2840-2600 CM−1

Infrared spectra: intramolecular trans lone pair interaction with α-CH bonds and the stability of conformers in alcohols and thiols

Raman spectra of aqueous solutions of dimethylsulfoxide, dimethylsulfoxide-d6, acetone and acetonitrile are reported in the OH stretching region, and in the stretching regions of the functional groups of these solutes. Raman intensities and frequency shifts of these bands show definite trends with varying concentrations of the solutions. The results obtained are discussed in terms of the mixture model of water, and they are compared with results obtained from Raman spectral studies of aqueous electrolytes. It is proposed that water structure breaking and the formation of solute-solvent complexes when organic solutes are added to water can account for these results.

Peter J. Krueger

Papers

Correlation between the stereochemistry of quinolizidine alkaloids and their infrared spectra from 2840-2600 CM−1

Infrared spectra: intramolecular trans lone pair interaction with α-CH bonds and the stability of conformers in alcohols and thiols

Raman spectral studies of aqueous solutions of non‐electrolytes: Dimethylsulfoxide, acetone and acetonitrile

Structural studies of monocations of sparteine and its stereoisomers by infrared spectroscopy

Infrared and Raman spectra of diethyl ether complexes of MgBr2 and MgI2