Synthesis of 4, 8-dihydroxy-3-methyl-5,6-benzo-2-oxabicyclo[2.2.2]oct-5-ene

The title compound having the same relative configurations as granaticin($\text{1}$) and U-58,431($\text{2}$) was prepared either by dehydrogenative cyclization of the precursor $\text{9a}$ or by pinacol cyclization of the dicarbonyl compound $\text{15}$.     

Proton and electron conductivity in hydrous ruthenium oxides evaluated by electrochemical impedance spectroscopy: the origin of large capacitance

Electrochemical impedance spectroscopy was conducted on a series of hydrous ruthenium oxides, RuO(2).xH(2)O, (x = 0.5, 0.3, 0) and a layered ruthenic acid hydrate (H(0.2)RuO(2.1).nH(2)O) in order to evaluate their protonic and electronic conduction. The capacitor response frequency was observed at lower frequency for RuO(2).xH(2)O with higher water content, which was suggested to be due to electrolyte exhaustion within the film and/or utilization of hydrated interparticle micropores that have high ionic resistance. Analysis of the impedance data indicated that the charge-transfer resistance through the film is not significantly affected by the water content in RuO(2).xH(2)O, and the capacitor frequency response is dominated by the protonic conduction. The capacitor response frequency of layered H(0.2)RuO(2.1).nH(2)O was comparable to RuO(2).0.5H(2)O. The high specific capacitance at low frequency for layered H(0.2)RuO(2.1).nH(2)O is attributed to the utilization of the expandable hydrous interlayer, which accounts for the ionic conduction. The present results demonstrate the importance of hydrous regions (either interparticle or interlayer) to allow appreciable protonic conduction for high energy and high power electrochemical capacitors.     

X-ray photoelectron spectrometric and x-ray fluorometric studies of sulphur compounds on the surface of copper plates exposed to the atmosphere

X-Ray photoelectron spectroscopy (XPS) and XRF as techniques for monitoring air pollution are compared. Sulphide and oxides of sulphur (SO(2), SO(3) and SO(2-)(4)) have been determined on copper plates exposed for different lengths of time to an atmosphere containing hydrogen sulphide. The total amount of sulphur increases with the time of exposure but the sulphide reaches a constant value after 59 days. An interpretation of the mechanism of oxidation of hydrogen sulphide is offered.     

Photochemical dechlorination of DDT catalyzed by a hydrophobic vitamin B12 and a photosensitizer under irradiation with visible light

Dechlorination of 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) was catalyzed by a hydrophobic vitamin B(12), heptamethyl cobyrinate perchlorate, with a visible light irradiation system containing a [Ru(ii)(bpy)(3)]Cl(2) photosensitizer, and the hydrophobic vitamin B(12) showed high catalytic efficiency and stability during the reaction.     

Ionic diffusion and salt dissociation conditions of lithium liquid crystal electrolytes

Salt dissociation conditions and dynamic properties of ionic species in liquid crystal electrolytes of lithium were investigated by a combination of NMR spectra and diffusion coefficient estimations using the pulsed gradient spin-echo NMR techniques. Activation energies of diffusion (Ea) of ionic species changed with the phase transition of the electrolyte. That is, Ea of the nematic phase was lower than that of the isotropic phase. This indicates that the aligned liquid crystal molecules prepared efficient conduction pathways for migration of ionic species. The dissociation degree of the salt was lower compared with those of the conventional electrolyte solutions and polymer gel electrolytes. This is attributed to the low concentration of polar sites, which attract the dissolved salt and promote salt dissociation, on the liquid crystal molecules. Furthermore, motional restriction of the molecules due to high viscosity and molecular oriented configuration in the nematic phase caused inefficient attraction of the sites for the salt. With a decreased dissolved salt concentration of the liquid crystal electrolyte, salt dissociation proceeded, and two diffusion components attributed to the ion and ion pair were detected independently. This means that the exchange rate between the ion and the ion pair is fairly slow once the salt is dissociated in the liquid crystal electrolytes due to the low motility of the medium molecules that initiate salt dissociation.     

Synthesis of polyamides by ring-opening polyaddition: Reaction of 4,4′-disubstituted bisazlactones with diamines

Ring-opening polyaddition of 4,4′-disubstituted bisazlactones with various diamines was carried out in N-methyl-2-pyrrolidone to afford polyamides with pendant amide group having inherent viscosities of 0.17-0.51 in quantitative yields. The solution polymerization with aliphatic diamines was almost complete at room temperature within 24 hr. Nearly all of the polyamides were soluble in polar in polar aprotic solvents and in acidic solvents. These polymers began to decompose at around 200–300°C as determined by DTA and TGA under nitrogen.     

Novel cluster ions from magnesium and zinc acetates in filament heated in-beam electron impact mass spectrometry

Mass spectral peaks of cluster ions believed to be due to penta-μ-acetato-μ₄-oxo-tetramagnesium and tri-μ-acetato-μ₃-oxo-trimagnesium, or the corresponding zinc compounds, were detected when magnesium acetate or zinc acetate was heated on a tungsten filament and impacted at the same time by an electron beam. Structures of these non-transition metal complexes are analogues of the so-called ‘electron-sponge’ complexes, [Ru₃O(OAc)₆L₃]. Previously reported new cluster ions from lithium acetate are formulated by similar structures.     

Carbocyclization by homolytic substitution (SH′ process). A new route to dihydroindole or dihydrobenzofuran

N-(4-Phenylthio-2-butenyl)-2-bromoaniline reacted with tributyltin hydride to give 3-vinyl-2,3-dihydroindole in 96% yield via hitherto unknown intramolecular S_H′ process, some other examples and remarkable dilution effect on these homolytic carbocyclizations were described.     

Enantioselective total synthesis of eurylene, 14-deacetyl eurylene, and their 11-epimers: the relation between ionophoric nature and cytotoxicity

[structure: see text] Enantioselective synthesis of eurylene, 14-deacetyl eurylene, and their 11-epimers was achieved. The characteristic structural feature of these compounds is two tetrahydrofuran (THF) rings substituted in different stereochemistry. The synthetic approach involves nonstereoselective THF ring formation to afford both segments from a common precursor. We also investigated their ionophoric nature and cytotoxicity. The complexation of these compounds with K(+) might be related to their cytotoxic activity.     

A novel fluorescent indicator for Ba2+ in aqueous micellar solutions

The highly selective and sensitive fluorescence detection of Ba(2+) among alkali metal and alkaline earth metal cations was successfully achieved in aqueous media by the combination of a novel monoazacryptand type of fluorophore and micelles of Triton X-100.