The photochemical isomerization of cross-linked 1,3,5-tristyrylbenzene dendrimer with hula-twist mechanism

A cross-linked 1,3,5-tristyrylbenzene dendrimer 5 was synthesized to study the photochemical isomerization mechanism. On irradiation, 5 isomerized with the quantum yields (Φ_E→Z) of 0.063, which was not very much different from that for a model compound 1 (Φ_E→Z 0.080), supporting a volume-conserving hula-twist (HT) mechanism during the photochemical E-Z isomerization.     

Characterization of two polysaccharides having activity on the reticuloendothelial system from the root of Glycyrrhiza uralensis

Two polysaccharides, called glycyrrhizans UA and UB, were isolated from the root of Glycyrrhiza uralensis Fischer. They were homogeneous on electrophoresis and gel chromatography, and showed reticuloendothelial system-potentiating activity in a carbon clearance test. Glycyrrhizan UA is composed of L-arabinose: D-galactose: L-rhamnose: D-galacturonic acid in the molar ratio of 20:14:1:3, and glycyrrhizan UB is composed of L-arabinose: D-galactose: D-glucose: L-rhamnose: D-galacturonic acid in the molar ratio of 12:10:1:10:20, in addition to small amounts of O-acetyl groups and peptide moiety, respectively. About 10% (glycyrrhizan UA) and 35% (glycyrrhizan UB) of the D-galacturonic acid residues exist as the methyl esters. Methylation analysis, carbon-13 nuclear magnetic resonance and periodate oxidation studies indicated their structural features.     

Esr studies on the γ-irradiated acetone-CCl3F system

γ-irradiated acetone in polycrystalline CCl₃F at 77 K has been studied by ESR to reveal that the acetone molecules tend to be oriented in CCl₃F Matrix upon freezing the solution in ESR tubings. At higher concentrations both monomer and dimer radical cations of acetone are produced. The dimer cation is responsible for the optical absorption with λ_max ≈ 740 nm.     

The application of multivariate analysis to the radioallergosorbent test (RAST)

Multivariate statistical analyses using principal component analyses (PCA) and Mahalanobis' method were applied to the quality control of radioallergosorbent test (RAST). Mites and foods allergen were analyzed by PCA method, and foods allergen were analyzed by Mahalanobis' method. The vast differences in the distribution on titers among the mites and the foods were observed. To evaluate the results of a test and the quality of kits for test statistically, it should be better to use multivariate analyses such as PCA or Mahalanobis' method.     

Distribution behavior of some drug enantiomers in an aqueous two-phase system using counter-current extraction with protein

Summary The partial resolution of some drug enantiomers by counter-current extraction in an aqueous two-phase system using bovine serum albumin (BSA) or ovomucoid (OVM) as chiral discriminator is described. The phase system was prepared with dextran 40, polyethylene glycol and a protein. Ofloxacin (OFLX) enantiomer was well recognized by the BSA system, whereas the enantiomers of carvedilol (-blocker) and DG-5128 (a new oral hypoglycaemic drug) were hardly recognized by the OVM system. The distribution coefficients of (S)-, (R)- and rac-OFLX varied with pH. Good enantioselectivity for OFLX was obtained at relatively high pH ( pH 9). The crude optically enriched OFLX enantiomers were extracted from the aqueous fractions and finally purified by thin-layer chromatography.     

Total synthesis of (+)-cylindricine C

A stereoselective total synthesis of (+)-cylindricine C has been achieved starting with (S)-N-Boc-2-pyrrolidinone. The key elements of this synthesis involve the sequence of reactions including BF₃-mediated addition of the allyl Grignard reagent to the cyclic imine, spirocyclization via enamine formation, and intramolecular Michael addition to form the tricyclic core.     

220-MHz NMR spectra of acrylic monomer–2-substituted 1,3-diolefin alternating copolymers

An investigation by 220-MHz NMR spectroscopy was carried out on the alternating copolymers of acrylic monomer with 2-substituted 1,3-diolefin. The chain structures were determined. The acrylic monomers used were methyl methacrylate (MMA), acrylonitrile (AN), and methacrylonitrile (MAN); isoprene (IP) and chloroprene (CLP) were the 1,3-diolefins. In the MAN–IP alternating copolymer, the 1-position methylene protons of IP showed an AB quartet peak, confirming the α-1 linkage structure. Similarly, in the MMA–CLP and AN–CLP copolymers, the 1-position methylene protons of CLP showed and AB quartet and an ABX pattern, respectively, confirming the α-1 linkage structure in both these cases also. The α-1 linkage structure was also revealed by the decoupling technique in the MAN–CLP alternating copolymer. The AN–IP and MMA–IP alternating copolymers also possess a bond between the α-position of the acrylic monomer and the 1-position of IP. The monomeric units in the alternating copolymers of acrylic monomers with 2-substituted 1,3-diolefins were generally linked at the α-position of acrylic monomer and the 1-position of 1,3-diolefin. On the other hand, in the Diels-Alder adducts of acrylic monomer with 2-substituted 1,3-diolefin, the reaction takes place between the α-position of acrylic monomer and the 4-position of 1,3-diolefin. The regioselectivity of the alternating copolymers and the Diels-Alder adducts is quite compatible with the expectations from molecular orbital theory.     

Ionic conduction of the perovskite-type halides

The ionic conduction in the perovskite-type halides, CsPbCl₃, CsPbCl₃ and KMnCl₃, was studied. Measurements were made of ac conductivity at temperatures from 150°C to the melting point, and of ionic transport number using the Tubandt, EMF and ion-blocking methods. The effects of impurity doping on the ionic conductivity of CsPbCl₃ were also studied using the samples of composition, CsPb_0.99M_0.01Cl_2.99 (M = Li, Na, K, Ag). It was concluded that these materials are halide-ion condcutors. The ionic conductivities of CsPbCl₃ and CsPbBr₃ are close to those of the well known halide-ion conductors, PbCl₂ and PbBr₂. The ionic transport numbers were found to be > 0.9 for CsPbCl₃ and CsPbBr₃, and about 0.99 for KMnCl₃. The conduction was considered to be caused by the migration of halide-ion vacancies V_X (X = Cl, Br). The activation energies for the migration of V_X were 0.29 eV for CsPbCl₃, 0.25 eV for CsPbBr₃ and 0.39 eV for KMnCl₃. The vacancy diffusion coefficients of these materials were found to be verylarge. However, the impurity doping did not increase the ionic conductivity markedly because of small dopant solubility.     

Swelling effect onα-relaxation in high density polyethylene

Summary Swelling effects of carbon tetrachloride on the mechanical relaxations in the crystal mat and the melt-crystallized samples of high density polyethylene were studied using a torsion pendulum. A very strong-relaxation peak appears by swelling at the low temperature side of the original-relaxation for the crystal mat. It was shown that this strong-relaxation originates from the slippage between the highly swollen lamellae. For the melt-crystallized sample, the-relaxation peak is decreased by swelling, but its temperature is unchanged. This behavior suggests that the-relaxation in the melt-crystallized sample originates mainly from deformation process of intermosaic block region. The swelling effect on-relaxation was also discussed.

---

Zusammenfassung Quellungseffekte von Tetrachlorkohlenstoff auf das mechanische Relaxationsverhalten in Einkristall-Matten und schmelzkristallisierten Proben von linearem Polyäthylen wurden mit den Torsionspendeln untersucht. Ein sehr starkes-Maximum tritt durch die Quellung bei tieferen Temperaturen als der der-Relaxation in den nicht gequollenen Einkristall-Matten auf. Es wird gezeigt, daß diese starke-Relaxation auf das Gleiten der ausreichend gequollenen Lamellen zurückzuführen ist. Bei schmelzkristallisierten Proben wird das-Maximum durch die Quellung erniedrigt, seine Temperaturlage wird jedoch nicht verändert. Dies zeigt, daß die-Relaxation in der schmelzkristallisierten Probe hauptsäcblich auf Deformations-Prozessen in den Blöcken beruht. Auch die Quellungseffekte auf die-Relaxationen wurden diskutiert.

     

Diastereoselective imino-aldol condensation of chiral 3-(p-Tolylsulfinyl)-2-furaldimine and ester enolates

(Ss)-3-(p-Tolylsufinyl)-2-furaldimine was synthesized, and condensation of the chiral furaldimine with lithium ester enolates has been examined. The product distribution of the reaction is dependent upon reaction conditions and on the kind of the substituent placed on the esters. Disubstituted ester enolate resulted in the exclusive formation of (4R)-beta-lactam, while unsubstituted, tert-butyl ester enolate preferentially gave (3R)-beta-amino ester. With the monosubstituted ester enolates, the condensation afforded (4R)-beta-lactams and/or (3R)-beta-amino esters as major products. This method has been applied to an efficient route to chiral furyl beta-lactams.