Rapid oligosaccharide synthesis using a fluorous protective group

The Bfp-OH, a novel fluorous protecting reagent, was able to be easily prepared. The Bfp group was readily introduced to a carbohydrate, removed in high yield, and recyclable after cleavage. The use of the Bfp group made it possible to synthesize a pentasaccharide by minimal column chromatography purification. Each synthetic intermediate was able to be easily purified only by simple fluorous-organic solvent extraction and monitored by TLC, NMR, and MS.     

Synthesis of peptides and oligosaccharides by using a recyclable fluorous tag

A hexakis(fluorous chain)-type alcohol was used in the synthesis of oligosaccharides and peptides through connection with a linker suitable for the particular type of target compound. After the preparation of the desired compound, the fluorous alcohol was easily recovered in good yields under basic conditions. It appears that the fluorous alcohol can be recovered, recycled, and reused.     

Post-oxidative conversion of thiol residue to sulfonic acid in the binding sites of molecularly imprinted polymers: disulfide based covalent molecular imprinting for basic compounds

An imprinted polymer using a disulfide derivative as a template was treated with NaBH4 to yield the polymer with thiol groups in the binding sites. The thiol groups were then oxidized with H2O2/AcOH to yield the molecularly imprinted polymer with sulfo groups in the binding sites. This site conversion can provide amine-imprinted polymers, in which amine is retained to the imprinted polymer by the strong electrostatic interaction between the amino group and the sulfo group in the binding sites.     

An application of silaned glass beads to the preconcentration and spectrophotometric determination of traces of phosphorus with molybdate

Silaned glass beads are applied to the preconcentration and spectrophotometric determination of phosphorus as the phosphomolybdenum blue complex. Traces of phosphorus in water are collected as a phosphomolybdenum blue complex on a column of the beads. The phosphomolybdenum blue is eluted with N,N-dimethylformamide and the absorbance of the eluate continuously monitored at 700 nm. The height of the very sharp peak obtained is proportional to the amount of phosphorus present and 0.1-0.5 mug of phosphorus in a 10-ml sample can be determined reproducibly. Interference from arsenate is eliminated by addition of a reducing agent. High concentrations of silica cause a small positive error. This method is applicable to the analysis of river water and sea-water samples.     

Two-step preparation for catalyst-free biodiesel fuel production

Biodiesel fuel was prepared by a two-step reaction: hydrolysis and methyl esterification. Hydrolysis was carried out at a subcritical state of water to obtain fatty acids from triglycerides of rapeseed oil, while the methyl esterification of the hydrolyzed products of triglycerides was treated near the supercritical methanol condition to achieve fatty acid methyl esters. Consequently, the two-step preparation was found to convert rapessed oil to fatty acid methyl esters in considerably shorter reaction time and milder reaction condition than the direct supercritical methanol treatment. The optimum reaction condition in this two-step preparation was 270°C and 20 min for hydrolysis and methyl esterification, respectively. Variables affecting the yields in hydrolysis and methyl esterification are discussed.     

Reductive metabolism of nitro-p-phenylenediamine by rat liver

Reductive metabolism of the hair dye constituent, nitro-p-phenylenediamine (2-nitro-1,4-diaminobenzene, NPDA), and its acetylated metabolite, NPDA N4-acetate, was investigated with rat liver subcellular fractions, microsomes and cytosol. Under anaerobic conditions, these compounds were reduced to their corresponding amines by these fractions. The microsomal nitro-reducing activity was retarded completely by air and strongly by carbon monoxide. Reduced nicotinamide adenine dinucleotide phosphate (NADPH) functioned more effectively than reduced nicotinamide adenine dinucleotide (NADH) as an electron donor in the microsomal reduction of the nitro compounds, and flavin mononucleotide (FMN) gave rise to a marked enhancement in the microsomal activity, especially when added to an anaerobic incubation mixture containing both NADH and NADPH. The cytosolic nitro-reducing activity was attributed to xanthine oxidase, aldehyde oxidase and other unknown enzyme(s), based on the results of cofactor requirements and inhibition experiments.     

Raman spectra of stilbene negative ions in tetrahydrofuran solution

Raman spectra of stilbene mono- and di-negative ions in tetrahydrofuran solution were obtained by Ar⁺ laser exciting lines. A considerable frequency shift was observed for several vibrations in the successive steps: stilbene → (stilbene)^? → (stilbene)^2?. The observed shift is discussed in a simple VB scheme, particularly in comparison with the results on anthracene negative ions. The resonance Raman effect was striking for both ions with intensity maxima at the exciting wavelengths close to the absorption maxima.     

Determination of some rare-earth elements by plasma-jet emission spectrometry

The effects of a magnetic field on spectral intensities in plasma-jet spectrometry were examined, and detection limits for rare-earth elements were calculated. Plasma-jet emission spectrometry was applied to the determination of lanthanum, yttrium and gadolinium in a monazite sample from which thorium had been separated. A standard addition method was used in order to improve accuracy, and the internal standard and background compensation method was applied to measurements of spectral line intensities to achieve good precision. The coefficient of variation was 1.51% for 50 μg La ml^?1.