Inductively-coupled plasma/atomic emission spectrometry of sulfur with a vacuum scanning spectrometer and its application to the analysis of coal liquefaction catalysts

Inductively-coupled plasma/atomic emission spectrometry with a high-resolution vacuum scanning monochromator is described for the determination of sulfur at 180.734 nm. The behavior of the signal-to-background ratio is investigated as functions of RF power, argon gas flow rate and observation height above the load coil. Under the operating conditions selected, the detection limit is 3 μg l^?1. The Se I 196.090-nm line is chosen as internal standard, because the S/Se line pair exhibited the least change with carrier gas flow rate and acid concentration of solution. Sulfur in NiMo and CoMo/ Al₂O₃ catalysts used for coal liquefaction is determined as S(II) and S(VI) species. The total amount of the species agreed well with the sulfur value obtained by the conventinal combustion method.     

Determination of thickness, dielectric constant of thiol films, and kinetics of adsorption using surface plasmon resonance

This paper describes the formation of a self-assembled monolayer of 11-mercaptoundecanoic acid (MUA) under different concentrations on a gold sensor disk, monitoring in situ and in real time using surface plasmon resonance spectroscopy (SPR). The film thickness and dielectric constant were determined for a fully formed monolayer using one-color approach SPR. The kinetic studies of the film formation in ethanol solution indicated that the self-assembled monolayer is formed in a two-step adsorption process. In this sense, this unpublished route was applied on the basis of a model where many molecules are adsorbed at an initial step and then can be desorbed and/or rearranged to form a perfect monolayer.     

Synthesis of a Stimuli‐Responsive P‐Chiral Polymer with Chiral Phosphorus Atoms and Azobenzene Moieties in the Main Chain

A reaction of the P‐chiral compound (S,S)‐1,2‐bis(boranato(tert‐butyl)methylphosphino)ethane with an azobenzene derivative gave stimuli‐responsive polymers with P‐chiral phosphines in the main chain. This is the first example of a stimuli‐responsive P‐chiral polymer. The polymer isomerized from the trans to the cis form upon UV irradiation and reverted to the trans form reversibly. The polymer was able to coordinate to platinum, and the resulting polymer complex exhibited the Cotton effect owing to the chirality of the phosphorus atoms. The structure of the P‐chiral polymer obtained could be changed reversibly by light and thermal stimuli, and the polymer chain was induced to rotate helically when complexed with transition metals through the chiral phosphorus atoms.     

Analytical approach to the discoloration of edible laver "nori" in the Ariake Sea.

To understand the cause of discoloration of the sea laver "nori," which is found in the Ariake Sea, the concentrations of pigments and elements in the normal and discolored laver samples were determined. In the discolored samples, a decrease in all of the pigments, chlorophyll a and carotenoids, and proteinous pigments, phycobiliproteins, was clearly observed. This was accompanied by a decrease in the content of Fe, Zn, Mn, Cu, and P. Good correlations between these elements and chlorophyll a, as well as between these elements and phycobiliproteins, were confirmed, indicating that, in addition to the deficiency of nitrogen and phosphorus, the deficiency of trace elements (Fe, Zn, Mn, and Cu), which are specifically required for photosynthesis, could be a reason for the discoloration of nori. The cause of elemental deficiency is also discussed.     

Diastereoselective inter- and intramolecular pinacol coupling of aldehydes promoted by monomeric titanocene(II) complex Cp(2)TiPh

A monomeric titanocene(III) derivative, Cp(2)TiPh, effectively promoted the pinacol coupling of both an aromatic aldehyde, benzaldehyde, and an aliphatic aldehyde, 3-phenylpropionaldehyde. The same reactive complex was successfully generated by a catalytic amount of a precursor, Cp(2)Ti(Ph)Cl, and its stoichiometric amount of Zn. The Cp(2)TiPh-catalyzed pinacol coupling of benzaldehyde derivatives and aliphatic aldehydes afforded the corresponding 1,2-diols in high yields with moderate to good threo-selectivity. On the other hand, Cp(2)TiPh-catalyzed pinacol cyclization of dials gave cyclic 1,2-diols with excellent diastereoselectivity. The extension of this protocol to chiral dials demonstrated that the phenyltitanium complex catalytically transmitted an axial chirality or a central chirality of the starting dials to the central chirality of the resultant 1,2-diols.     

Structures of Ganoderic Acid A and B,Two New Lanostane Type Bitter Triterpenes from Ganoderma lucidum (FR.) KARST.

The structures of two new bitter triterpenes, ganoderic acid A and B. isolated from a mushroom Ganoderma lucidum (FR.) Karst. (Polyporaceae) were determined as 1 and 2 on the basis of spectral data. Ganoderic acid A is a novel highly oxidized triterpene bearing a boat-shaped A-ring of lanostane.     

One-pot synthesis of phenol and cyclohexanone from cyclohexylbenzene catalyzed by N-hydroxyphthalimide (NHPI)

Synthesis of phenol and cyclohexanone in one pot was examined by means of the NHPI-catalyzed aerobic oxidation of cyclohexylbenzene. The aerobic oxidation of cyclohexylbenzene catalyzed by NHPI followed by treatment with sulfuric acid afforded phenol and cyclohexanone in good selectivities. Thus, the reaction of cyclohexylbenzene under atmospheric dioxygen (1 atm) by NHPI at 100 °C for 3 h followed by treatment with 0.3 M sulfuric acid at room temperature for 2 h resulted in phenol and cyclohexanone in 96 and 91% selectivity, respectively, at 25% conversion. This method was successfully extended to the one-pot synthesis of 4-hydroxyacetophenone and cyclohexanone.     

Cation binding properties of crown ether-modified polyethylenimines

Crown ether-modified polyethylenimines (PEI-CR) were prepared to elucidate their cation binding efficiency and selectivity by liquid-liquid and solid-liquid extraction methods. With alkali metal cations it was found that polyethylenimines containing benzo-15-crown-5 moieties (Ia and Ib) extracted all cations examined more efficiently than their monomeric analogs, especially in the cases of K⁺ and Rb⁺ cations. The solid-liquid extraction revealed clearly that the polymers complexed with K⁺ and Rb⁺ cations according to a 1:2 cation-to-crown stoichiometry. The high selectivities of the polymers for K⁺ and Rb⁺ were interpreted in terms of the favourable conformation of the polymer chain for the formation of intramolecular 1:2 complexes. On the contrary, these polymers bound alkali earth cations less effectively with low selectivities.