Dual Si-H effects in platinum-catalyzed silane reduction of carboxamides leading to a practical synthetic process of tertiary-amines involving self-encapsulation of the catalyst species into the insoluble silicone resin formed

Combination of commercially available platinum catalysts with siloxanes containing more than two Si-H groups is found to be an efficient catalyst system for the reduction of carboxamides to amines. In particular, facile removal of silicon and platinum residues from the product can be achieved by the use of polymethylhydrosiloxanes as reducing reagents.     

Semiconducting organic polymer from polyacrylamide–Cu++ chelate and iodine

Semiconducting organic polymer was obtained by the modification of polyacrylamide (PAAm)–Cu⁺⁺ chelate with iodine in acetone. Favorable conditions for preparing the chelate effective for the conduction were investigated. Surface resistivities were affected by the amounts of cupric salts and iodine, satisfactory results being given by about 25 wt % of the salts based on PAAm and more than 1 wt % of iodine on the chelate. The conductivity was also varied with the degree of neutralization of the chelate in solution, and optimal values were obtained by addition of about an equimolar amount of potassium hydroxide to cupric salts. Effective structures of the polymer chelate in solution were assumed on the basis of the visible and the NMR spectra and potentiometric titration.     

Effect of titanium dioxide on photostability of solid-state mequitazine

TiO(2) has been widely used in pharmaceutical products, and it also has been used as a photocatalyst. In this study, the influence of photocatalytic activity on the stability of solid-state mequitazine, an H(1)-blocker, was investigated. The photo-degradation of mequitazine with TiO(2) occurred under irradiation with both light sources. The degree of degradation of mequitazine with anatase was higher than that of rutile. The degradation was significantly enhanced with increasing relative humidity. The relationship between the apparent degradation rate constant and water vapor pressure could be clearly described by a simple power law. The major photo-degradation products of mequitazine, resulting from photocatalytic activity of TiO(2), were mequitazine-S-oxide and mequitazine-sulphone. A remarkable degradation of mequitadine occurred with addition of TiO(2), and its photocatalytic activity was controlled by water vapor pressure. The photo-degradation of mequitazine with TiO(2) is a different process from mequitazine without TiO(2), because mequitazine-S-oxide and mequitazine-sulphone are not formed with normal photo-degradation of mequitazine.     

Preparation and properties of rare-earth containing oxide fluoride glasses

The preparation of the rare earth containing oxide fluoride glasses LnF₃ (Ln; Y through Lu)-BaF₂-AlF₃-GeO₂ in which the nominal content of LnF₃ reached 60 mol% in maximum and their basic properties such as density, refractive index and glass transition temperature were investigated and summarized in detail. Especially, in order to discuss the local structure around the rare earth ion in the glass, the Judd-Ofelt analysis (discussion with Ω parameters) of the HoF₃-BaF₂-AlF₃-GeO₂ glasses was carried out. The unique fluorescent behavior and the magnetic properties of LnF₃-BaF₂-AlF₃-GeO₂ glasses (Ln = Tb and/or Sm) were also studied.     

Rapid and simple method for the determination of alpha 1-acid glycoprotein in serum by column liquid chromatography.

A rapid and simple method for the determination of alpha 1-acid glycoprotein (AAG) in serum was developed by using an anion-exchange column for clean-up of serum and a hydroxyapatite column for high-performance liquid chromatography (HPLC). A good correlation was observed between this HPLC method and the conventional radial immunodiffusion method. The method may also be used to determine the AAG concentration in the serum of experimental animals.     

Identification of Site-Specific Degradation in Bacterially Expressed Human Fibroblast Growth Factor 4 and Generation of an Aminoterminally Truncated,Stable Form

Fibroblast growth factor 4 (FGF4) is considered as a crucial gene for tumorigenesis in humans and the development of mammalian embryos. The secreted, mature form of human FGF4 is thought to be comprised of 175 amino acid residues (proline³² to leucine²⁰⁶, Pro³²-Leu²⁰⁶). Here, we found that bacterially expressed, 6× histidine (His)-tagged human FGF4 (Pro³²-Leu²⁰⁶) protein, referred to as HishFGF4, was unstable such as in phosphate-buffered saline. In these conditions, site-specific cleavage, including between Ser⁵⁴ and Leu⁵⁵, in HishFGF4 was identified. In order to generate stable human FGF4 derivatives, a 6× His-tagged human FGF4 (Leu⁵⁵-Leu²⁰⁶), termed HishFGF4L, was expressed in Escherichia coli. HishFGF4L could be purified from the supernatant of cell lysates by heparin column chromatography. In phosphate-buffered saline, HishFGF4L was considered as sufficiently stable. HishFGF4L exerted significant mitogenic activities in mouse embryonic fibroblast Balb/c 3T3 cells. In the presence of PD173074, an FGF receptor inhibitor, the growth-stimulating activity of HishFGF4L disappeared. Taken together, we suggest that HishFGF4L is capable of promoting cell growth via an authentic FGF signaling pathway. Our study provides a simple method for the production of a bioactive human FGF4 derivative in E. coli.     

Spectral analysis of Sr 3d XPS spectrum in Sr-containing hydroxyapatite

The Sr 3d X-ray photoelectron spectroscopy (XPS) spectrum of Sr-containing hydroxyapatite (SHAp) overlaps completely with the P 2p spectrum. Thus, the chemical state identification of Sr in SHAp is a challenging task. In this work, the Sr 3d spectrum was isolated from the overlapping spectra for analyzing the chemical state of Sr using a generic peak-fitting method. The SHAp layers containing various Sr concentrations were produced on a Ti substrate using a chemical treatment process with a calcium phosphate slurry that included Sr (NO₃)₂. The distribution of the constituent elements changed according to the Sr concentration, implying that the chemical state of Sr varied with concentration. The isolation of the Sr 3d XPS spectrum was conducted via spectral deconvolution using the P 2p spectrum corresponding to HAp. The isolated Sr 3d spectrum revealed that the chemical state of Sr was in SrO and Sr-substituted HAp states, and their ratio varied with the Sr concentration in the layer. The SrO to Sr-substituted HAp ratios affected the Sr ion releasing behavior from the SHAp layer, supporting the validity of the obtained analytical results.     

Specific reactivity of 2,4,6-tri-tert-butylanilide anions and its application to benzylation reagent

The reaction of methyl iodide with an anilide anion prepared from 2,4,6-tri-tert-butylanilide and NaH in CH₃CN gave N-methyl anilide (N-alkylation product) as a major product, while in the reaction of benzyl bromide with the anilide anion in DMF, O-benzyl imidate (O-alkylation product) was obtained with almost complete selectivity. The treatment of O-benzyl imidate with alcohols and carboxylic acids in the presence of trifluoromethane sulfonic acid gave benzyl ethers and benzyl esters, respectively.     

Rapid enantioseparation of 1-aminoindan by microchip electrophoresis with linear-imaging UV detection.

Chiral separations of 1-aminoindan (AI) by cyclodextrin electrokinetic chromatography (CDEKC) were investigated on microfluidic quartz chips. By using a microchip electrophoresis (MCE) instrument equipped with a linear-imaging UV detector, the separation process of the enantiomeric compounds was observed. When sulfated beta-cyclodextrin was employed as a chiral selector, the baseline separation of AI could be achieved within 1 min with a high repeatability. The relative standard deviation of the migration time was less than 6%. The fastest separation was achieved in 14 s, utilizing a separation length of only 6.1 mm. These results show that the MCE analysis employing a linear imaging UV detector has a significant potential for fast chiral analysis.     

Reaction of germabenzenylpotassium with TBDMSCl: Unusual trimerization of germabenzene skeletons

Abstract

The reaction of 2-t-Bu-germabenzenylpotassium with Me₂(t-Bu)SiCl (TBDMSCl) resulted in the coupling among two TBDMS-substituted germabenzenes and the germabenzenylpotassium. The structure of the product was determined by X-ray crystallographic analysis. Its formation mechanism was proposed with the help of theoretical calculations.