Magnetic properties of anhydrous and hydrous modifications of potassium-chloranil salt

The temperature dependence of magnetic susceptibility was studied on the anhydrous and hydrous modifications of the potassium-chloranil salt. While the anhydrous salt exhibits a phase transition at 210–270 K from the low spin state to the high spin state, the hydrous modification shows no such phase transition, and remains in a low spin state over the whole temperature range, 70–300 K.     

Determination of rhenium by neutron activation

A neutron activation method is proposed for the determination of rhenium in rocks and ores. After the irradiation, the radiochemical separation consists of a one-step anion exchange; β-activities of radiochemically pure ¹⁸⁸Re or ¹⁸⁶Re are counted. The chemical yield averaged 75% and there was a considerable saving of time in the radiochemical work. Results are quoted for the rhenium contents of the standard rock W-1, several molybdenites and pyrolusites.     

A concise and practical catalytic asymmetric synthesis of (−)-CP-99,994 and (−)-L-733,061

A concise and practical catalytic asymmetric synthesis of (−)-CP-99,994 and (−)-L-733,061 was achieved. Key features involve the Pd-catalyzed asymmetric allylic amination and the ring-closing metathesis as key steps.     

Self-aggregation of synthetic protobacteriochlorophyll-d derivatives

3(1)-Racemically pure zinc 3(1)-hydroxy-13(1)-oxo-porphyrins (zinc methyl 17,18-dehydro-bacteriopheophorbides-d) as well as their 3(1)-demethyl form were prepared by modifying chlorophyll-a through oxidation by 2,3-dichloro-5,6-dicyano-benzoquinone. From visible, circular dichroism and infrared spectral analyses, these synthetic pigments self-aggregated in 1%(vol/vol) tetrahydrofuran and cyclohexane to give large oligomers by an intermolecular bonding of 13-C=O...H-O(3(1))...Zn(central) and pi-pi interaction of the porphyrin chromophores. The supramolecular structures are similar to those of the corresponding chlorins and a core part of extramembranous light-harvesting antennas of photosynthetic green bacteria. The 17,18-dehydrogenation of a chlorin to porphyrin moiety did not disturb its self-aggregation and the synthetic zinc porphyrins are good models for naturally occurring self-aggregative bacteriochlorophylls.     

Pyrolysis of arylglycol-β-propylphenyl ether lignin model in the presence of borosilicate glass fibers. : I. Pyrolysis reactions of β-ether compounds

Two β-aryl ether type model compounds, guaiacylglycol- and veratrylglycol-β-propylphenyl ethers, were copyrolyzed with borosilicate glass fibers. The results provided a better understanding of the effect of copyrolysis with the fibers on the yields of lignin-derived products from lignocellulosics.

The observed products indicated the following reactions occurring in the models; (1) cleavage of the C-aromatic ring bond, (2) cleavage of the β-ether bond, (3) cleavage of the C-Cβ bond, (4) ,β-dehydration, and (5) demethylation, and others. Of these reactions, reactions (1), (2) and (4) were the main pyrolysis reactions and fully explained the increase in the total yield of lignin-derived pyrolysis products from Japanese red pine (Pinus densiflora Sieb. et Zucc.) in the presence of borosilicate glass fibers. Reaction (1) was a particularly characteristic reaction in copyrolysis with the fibers. Important reactions relating to the increase in the total yield of lignin-derived pyrolysis products were reproduced on the models used.     

Quantification of methamphetamine, amphetamine and enantiomers by semi-micro column HPLC with fluorescence detection; applications on abusers' single hair analyses

Achiral and chiral semi-micro column high-performance liquid chromatographic methods with fluorescence detection to determine methamphetamine and amphetamine in human hair are described. These compounds were extracted into 5% trifluoroacetic acid (TFA) in methanol, derivatized with 4-(4,5-diphenyl-1H-imidazol-2-yl)-benzoyl chloride and separated either on a 250 x 1.5 mm i.d. octadecyl-silane (ODS) or a 150 x 2 mm i.d. OD-RH column. Linear calibration curves extending over a wide range of concentration that covers the practical samples were obtained for amphetamine, methamphetamine and their enantiomers (r = 0.999). Resolution values for amphetamine and methamphetamine enantiomers were 3.4 and 1.1, respectively. Intra- and inter-day variations of both the methods were not larger than 8.9% expressed as relative standard deviations (n >/= 5). The limits of detection at a signal-to-noise ratio of 3 obtained by both the methods were in the range of 1.0-4.7 fmol/5 microL injection with the achiral method being more sensitive. Abusers' hair samples were analyzed by the two methods and only the S(+)-enantiomers were found in eight Japanese abusers' hair samples. The achiral method was used to study the concentrations of these compounds in single black and white hair strands of abusers.     

Cholestane glycosides from the bulbs of Galtonia candicans and their cytotoxicity

Further search for cytotoxic compounds contained in the bulbs of Galtonia candicans (Liliaceae) led to the isolation of four potent cytotoxic cholestane glycosides (1-4) based upon 3beta,16beta,17alpha-trihydroxycholest-5-en-22-one, three of which (2-4) have not been reported previously. A new cholestane bisdesmoside (5) and a new rearranged cholestane glycoside (6) were also isolated. The structural assignment of the new constituents was carried out by spectroscopic analysis and a few chemical transformations.     

Synthesis and reactions of 1,2-fused 3-cyanoindolizines

With the intention that annulation of carbo- or heteroaromatic rings at the 1,2-positions can activate 3-cyanoindolizines as 1,3-dipolar species, 6-cyanobenz[a]indolizines, pyridazino[4,5-a]indolizines and 5-cyano-1,3-diphenylthiopheno[3,4-a]indolizine were prepared. 6-Cyanobenz[a]indolizines smoothly -underwent 1,3-dipolar cycloaddition on to dibenzoylacetylene and diacetylacetylene to afford the corresponding indolizino[3,4,5-ab]isoindoles, whereas 5-cyano-1,4-diphenylpyridazino[4,5-a]indolizine reacted with dimethyl acetylenedicarboxylate to give the 1:2 adduct. Only a 3% yield of 5-cyano-1,3-diphenylthiopheno[3,4-a]indolizine formed upon phosphorus pentasulfide treatment of 1,2-dibenzoyl-3-cyanoindolizine.     

Aldehyde-selective addition of alkynylchromium compounds prepared by reduction of alkynyl halides with chromium(II) reagent

Alkynyl halides are reduced by chromium(II) chloride in DMF to give unisolable alkynylchromium compounds which add selectively to an aldehyde moiety without affecting the coexisting ketone group of the substrate.     

Anion-exchange behavior of various metals in hydrazoic acid media

The adsorption characteristics for 43 metals on a strongly basic ion-exchange resin Bio-Rad AG1 were examined in 0.5 M hydrazoic acid solution. The distribution coefficients for V(IV), Fe(III), Cu(II), Zn, Se(IV), Mo(VI), Pd(II), Cd, In(III), Rc(VII), Hg(II) and U(VI), which showed very strong adsorption except for Cd, were measured as a function of hydrazoic acid concentration over the range 0.05–0.5 M. Favorable differences in the distribution coefficients allow useful two- and three-component separations such as Co(II)-Fe(III), As(III)-V(IV), Cd-Zn, Cd- Hg(II), Te(IV)-Se(IV), Th-U(VI), Mn(II)-Mo(VI)-Re(VII), to be achieved on a small column.