A new pharmacological testing method--different effects of levamisole and the serum of mice orally treated with levamisole on mitogenic activity of lipopolysaccharide

The direct addition of levamisole to murine splenic lymphocytes had no effect on the mitogenic activity of lipopolysaccharide. However, the addition of serum of mice orally treated with levamisole increased the mitogenic activity, and this increased activity using serum was similar to the result obtained in an in vivo experiment. These results suggest that the new in vitro experimental method using serum may be able to reproduce the in vivo effect of drugs.     

Photopolymerization of methyl methacrylate in the presence of tertiary amines

The sensitization effect of tertiary amines on the photopolymerization of methyl methacrylate was studied. N,N-Dimethylbenzylamine, triethylamine, and N,N-dimethylaniline increased the rate of polymerization in this order, but pyridine did not show any effect. A free-radical mechanism was confirmed by the tacticity of polymer, the retarding effect of hydroquinone, and the copolymer composition with styrene. On the basis of the detailed kinetics of the sensitized polymerization and the ultraviolet spectra of the reaction mixtures, a sensitization mechanism is proposed, in which the excited monomer and the amine form a complex and generate an initiating radical.     

Rapid ruthenium-catalyzed synthesis of pyranopyrandiones by reconstructive carbonylation of cyclopropenones involving C[bond]C bond cleavage

Pyranopyrandiones were prepared by a novel ruthenium-catalyzed carbonylative dimerization of cyclopropenones via C-C bond cleavage. For example, treatment of dipropylcyclopropenone with a catalytic amount of Ru3(CO)12 and NEt3 in THF under 15 atm of carbon monoxide at 140 degrees C for 20 h gave a novel functional monomer, 3,4,7,8-tetrapropylpyrano[6,5-e]pyran-2,6-dione, in an isolated yield of 81%. Unsymmetrically substituted pyranopyrandiones were also obtained by ruthenium-catalyzed carbonylative coupling of cyclopropenones with alkynes under similar reaction conditions.     

Emission-spectrometric determination of trace non-rare earth elements in yttrium oxide using AgF-Ga2O3 mixed carrier

Summary An emission-spectrometric method is described for the quantitative determination of traces of non-rare earth elements in yttrium oxide, employing addition of AgF-Ga₂O₃ mixed carrier. This addition effects an increase of the rate of evaporation of the analytical elements and of the number of atoms in the arc plasma. It enhances the sensitivity of the analytical elements to a larger extent than other carriers and permits the determination of microquantities of the elements (Mg, Ca, Mn, Co, Fe, Pb, Cu, Cd, Al, B, Sn, As, Bi) within limits of detection from 0.1 to 13 ppm in high-purity yttrium oxide. The coefficients of variation are less than 20%.

---

Emissionsspektrometrische Bestimmung von nicht zu den Seltenen Erden gehörenden Elementspuren in Yttriumoxid mit Hilfe eines AgF-Ga₂O₃ -Trägergemisches

Zusammenfassung Das Trägergemisch bewirkt eine Erhöhung der Verdampfungsgeschwindigkeit der zu bestimmenden Elemente und der Anzahl der Atome im Bogenplasma. Es verbessert mehr als andere Träger die Empfindlichkeit und ermöglicht die Bestimmung von Mikromengen der Elemente (Mg, Ca, Mn, Co, Fe, Pb, Cu, Cd, Al, B, Sn, As, Bi) in hochreinem Yttriumoxid mit Nachweisgrenzen von 0,1–13 ppm. Die Variationskoeffizienten liegen unter 20%.

     

FLAVIN-PHOTOSENSITIZED MONOMERIZATION OF DIMETHYLTHYMINE CYCLOBUTANE DIMER IN THE PRESENCE OF MAGNESIUM PERCHLORATE

We have investigated the photosensitized monomerization of the cis,syn -cyclobutane dimer of 1,3-di-methylthymine using riboflavin tetraacetate and a 5-deazaflavin derivative as photosensitizer. Although little monomerization of the dimer is induced by photoexcitation of the flavins in the absence of any additives, the flavins can function as an efficient photosensitizer in the presence of magnesium perchlorate. Mechanistic studies involving spectroscopic, quantum-yield and flash-photolysis measurements demonstrated that the photosensitized monomerization exclusively proceeds through electron transfer from the dimer to the triplet flavins complexed with Mg²⁺. The effects of magnesium perchlorate are compared with those on the chloranil-photosensitized monomerization and also with the effects of HClO₄ on the flavin-photosensitized reaction.     

A new synthetic method: Direct replacement of the nitro group by hydrogen or deuterium

The nitro group in tertiary or secondary aliphatic nitro compounds is replaced by hydrogen or deuterium on treatment with tributyltin hydride or tributyltin deuteride, respectively.     

Characterization of the non-stoichiometric and isomorphic hydration and solvation in FK041 clathrate

FK041 crystallizes as a non-stoichiometric hydrate or as solvated hydrates which were characterized as isomorphic clathrates by powder X-ray diffractometry. Moisture and organic solvent vapor sorption studies, differential scanning calorimetry and thermogravimetric analysis revealed that FK041 monohydrate forms a physically stable host crystal, which has lattice channels for guest water and/or organic solvent molecules. The hydration state varies non-stoichiometrically between dihydrate and tetrahydrate depending on the relative humidity and the mol content of the co-existing organic solvent, that is 2-propanol, ethanol, or acetone. These organic solvents are thought to replace a part of originally present water with a mol ratio of 1:3. 2-Propanol exhibited the most stable solvation, indicating that the size and shape of 2-propanol are the most preferable to the lattice channels.     

Reaction of 2-dialkylamino-5-phenyl-1,3-oxathiolium cation with sulphur ylides

The reaction of 2-dialkylamino-5-phenyl-1,3-oxathiolium cation 1 with sulphur ylides 2 was investigated. The behavior of 1 was solvent-dependent. In CH₂Cl₂, carbamate ester 3 was obtained: in CH₃CN, the intermediate sulphonium salt 5, which on hydrolysis gave 3, was isolated. On the other hand, reaction in MeOH gave the diphenacyl derivative 6. The reaction mechanism is discussed.