Regioselectivity of Friedel-Crafts acylation of aromatic compounds with several cyclic anhydrides

The Friedel-Crafts acylations of various aromatic compounds with cyclic anhydrides such as 2-(p-substituted phenyl)butanedioic, 3-phenylpentanedioic and homophathlic anhydrides were carried out under various conditions in order to obtain informations about the regioselectivity of the ring opening of the cyclic anhydrides and about the possible reaction pathways in the acylations.     

Microchip electrophoretic protein separation using electroosmotic flow induced by dynamic sodium dodecyl sulfate-coating of uncoated plastic chips

Separation of sodium dodecyl sulfate (SDS)-protein complexes is difficult on plastic microchips due to protein adsorption onto the wall. In this paper, we elucidated the reasons for the difficulties in separating SDS-protein complexes on plastic microchips, and we then demonstrated an effective method for separating proteins using polymethyl methacrylate (PMMA) microchips. Separation difficulties were found to be dependent on adsorption of SDS onto the hydrophobic surface of the channel, by which cathodic electroosmotic flow (EOF; reversed flow) was generated. Our developed method effectively utilized the reversed flow from this cathodic EOF as a driving force for sample proteins using permanently uncoated but dynamic SDS-coated PMMA microchips. High-speed (6 s) separation of proteins and peptides up to 116 kDa was successfully achieved using this system.     

Synthesis of new hydrolyzable polyurethanes from L‐gulonic acid‐derived diols and diisocyanates

New polyurethanes with lactone groups in the pendants and main chains were synthesized by the polyaddition of two kinds of L ‐gulonolactone‐derived diols (2,3‐O‐isopropylidene‐L ‐gulono‐1,4‐lactone and 5,6‐O‐isopropylidene‐L ‐gulono‐1,4‐lactone) with hexamethylene diisocyanate and methyl (S)‐2,6‐diisocyanatohexanoate and by the subsequent deprotection of isopropylidene groups. They were hydrolyzed more quickly than the polyurethane derived from methyl β‐D ‐glucofuranosidurono‐6,3‐lactone in a phosphate buffer solution, the pH value of which was 8.0, at 27 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4158–4166, 2002     

Thalidomide as a nitric oxide synthase inhibitor and its structural development

Thalidomide has been found to exhibit weak nitric oxide synthase (NOS)-inhibitory activity. Structural development studies of thalidomide showed that some N-2,6-dimethylphenylhomophthalimide analogs possess NOS-inhibiting activity.     

Length dependence of the optical transition energies of the exactly solvable Hubbard model for linear polyenes

Some accurate results on the length dependence of the excitation energies from the ground state to ionic excited states in the Hubbard model of linear polyenes are obtained based on the method of Lieb and Wu. To this end, it is first shown that singly ionic excited states with “plus” alternancy symmetry in the Hubbard model are described by the wave functions in which the two electron operator [∑(?)ⁿCC] is acted on (N ? 2)-electron covalent eigenstates. Then by solving the Lieb-Wu equations the exact excitation energies of the lowest ionic state, which corresponds to the E state in this model, are calculated for systems with up to 50 electrons. The result, together with a correction for the end effect, indicates that the excitation energies do not decrease as 1/N but converge to the limiting value more rapidly when the number of electrons N becomes large.     

Control of charge-transfer-induced spin transition temperature on cobalt-iron Prussian blue analogues

The electronic and spin states of a series of Co-Fe Prussian blue analogues containing Na(+) ion in the lattice, Na(x)()Co(y)()Fe(CN)(6) x zH(2)O, strongly depended on the atomic composition ratio of Co to Fe (Co/Fe) and temperature. Compounds of Co/Fe = 1.5 and 1.15 consisted mostly of the Fe(III)(t(2g)(5)e(g)(0), LS, S = 1/2)-CN-Co(II)(t(2g)(5)e(g)(2), HS, S = 3/2) site and the Fe(II)(t(2g)(6)e(g)(0), LS, S = 0)-CN-Co(III)(t(2g)(6)e(g)(0), LS, S = 0) site, respectively, over the entire temperature region from 5 to 350 K. Conversely, compounds of Co/Fe = 1.37, 1.32, and 1.26 showed a change in their electronic and spin states depending on the temperature. These compounds consisted mainly of the Fe(III)-CN-Co(II) site (HT phase) around room temperature but turned to the state consisting mainly of the Fe(II)-CN-Co(III) site (LT phase) at low temperatures. This charge-transfer-induced spin transition (CTIST) phenomenon occurred reversibly with a large thermal hysteresis of about 40 K. The CTIST temperature (T(1/2) = (T(1/2) descending + T(1/2) ascending)/2) increased from 200 to 280 K with decreasing Co/Fe from 1.37 to 1.26. Furthermore, by light illumination at 5 K, the LT phase of compounds of Co/Fe = 1.37, 1.32, and 1.26 was converted to the HT phase, and the relaxation temperature from this photoproduced HT phase also strongly depended on the Co/Fe ratio; 145 K for Co/Fe = 1.37, 125 K for Co/Fe = 1.32, and 110 K for Co/Fe = 1.26. All these phenomena are explained by a simple model using potential energy curves of the LT and HT phases. The energy difference of two phases is determined by the ligand field strength around Co(II) ions, which can be controlled by Co/Fe.     

Characterization of phase transition of Ba2-xSrxIn2O5 by thermal analysis and high temperature X-ray diffraction

The phase transitions of Ba_2-xSr_xIn₂O₅ were investigated with various thermal analyses and high-temperature X-ray diffraction. It was clarified that crystal structure of Ba_2-xSr_xIn₂O₅ with x=0.0~0.4 varies from brownmillerite through distorted perovskite to another distorted perovskite with increase of temperature. The phase transition from brownmillerite to distorted perovskite was revealed to be first order, whereas transition from distorted perovskite to another one was second order. The specimen with x≥0.5 showed only one first order phase transition from brownmillerite to distorted perovskite. The phase diagram of Ba_2-xSr_xIn₂O₅ was established and existence of tricritical point at ~1100°C with x=0.4~0.5 was suggested. This revised version was published online in August 2006 with corrections to the Cover Date.     

Concentrations of 239,240Pu and 241Am of marine products in coastal waters of Ibaraki

More than 200 samples of marine products have been collected and analyzed for plutonium and almost 100 samples for americium around Hitachi, Tokai and Oarai in the pacific coast of Ibaraki prefecture. The data have shown that the concentration factor (CF) values for plutonium were 330 for bivalve, 770 for abalone (muscle) and 610 for brown algae. For americium, the CF was calculated as 2400 for bivalve, 1000 for abalone (muscle) and 420 for brown algae.     

Mechanisms and kinetics of trisodium 2-hydroxy-1,1'-azonaphthalene-3,4',6-trisulfonate adsorption onto chitosan

Chitosan, a naturally abundant biopolymer, has widely been studied for metal adsorption from various solutions, but the extension of chitosan as an adsorbent to remove organic substances from water and wastewater has seldom been explored. In this study, the adsorption of an azo dye, trisodium 2-hydroxy-1,1'-azonaphthalene-3,4',6-trisulfonate (1), from aqueous solution onto the various degrees of deacetylated chitosan has been investigated. Equilibrium studies have been carried out to determine the capacity of chitosan for dye. The experimental data were analyzed using two isotherm correlations, namely, Langmuir and Freundlich equations. The linear correlation coefficients were determined for each isotherm and the Langmuir provided the best fit. The experimental adsorption isotherms were perfectly reproduced in the simulated data obtained from numerical analysis on the basis of the Langmuir model and the isotherm constants. Adsorption of (1) onto the chitosan flakes was found to be strongly depending on degrees of deacetylation in chitosan and temperatures. Significant amounts of (1) were adsorbed by chitosan 8B (higher degree of deacetylated chitosan), but the adsorption capacity was reduced remarkably with increasing solution temperatures. Thermodynamic parameters such as change in free energy (DeltaG), enthalpy (DeltaH), and entropy (DeltaS) were also determined. In addition, kinetic study indicated that the adsorption process mechanisms were both transport- and attachment-limited.     

Enantioselective Synthesis of 3,4‐Dihydropyran‐2‐ones by Domino Michael Addition and Lactonization with New Asymmetric Organocatalysts: Cinchona‐Alkaloid‐Derived Chiral Quaternary Ammonium Phenoxides

Chiral quaternary ammonium phenoxides were readily prepared from commercially available cinchona alkaloids and proved to be useful new asymmetric organocatalysts. Among various chiral quaternary ammonium phenoxides, a cinchonidine‐derived catalyst that bears both a sterically hindered N1‐9‐anthracenylmethyl group and a strongly electron withdrawing 9‐O‐3,5‐bis(trifluoromethyl)benzyl group were found to be highly effective for the Michael addition of ketene silyl acetals (derived from phenyl carboxylates) and α,β‐unsaturated ketones followed by lactonization. Optically active 3,4‐dihydropyran‐2‐one derivatives were obtained in high yields with excellent control of enantio‐ and diastereoselectivity. This catalyst can be handled in air and stored at room temperature in a sealed bottle without decomposition for at least one month.