bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetic and Mechanism of the Electrochemical Reduction of Fluoranthene in N,N-Dimethylformamide
Authors: Abdel-Hamid Refat
Published: July 2006

Detailed mechanism of electrochemical reduction of fluoranthene has been studied by cyclic voltam-metric method in N,N-dimethylformamide solution using 0.1 mol dm−3 tetraethylammonium perchlorate as a supporting electrolyte. It was found that fluoranthene undergoes a reversible diffusion-controlled one electron-transfer wave followed by an irreversible one-electron one. The reaction in the presence of proton donor such as phenol was also studied. The results reveal that the kinetics of the reaction is first-order in anion radical, zero-order in fluoranthene and first-order with respect to phenol. The overall reaction is of the ECEh type. It is concluded that the mechanism of the electrochemical reduction of fluoranthene consists of (a) heterogeneous electron transfer to form an anion radical, (b) proton transfer reaction, (c) homogeneous electron transfer in which the neutral radical formed in (b) is reduced to the carbanion and finally (d) the rapid protonation of the carbanion.
The Fast and Selective Reduction of Organic Halides by Lithium Hydrotri-s-butylborate
Authors: Kim Sunggak , Yi Kyu Yang
Published: July 2006

Lithium hydrotri-s-butylborate is shown to be a powerful reducing agent in its reducing abilitie: toward organic halides and discriminates structurally different organic halides due to the bulkiness of the reagent Essentially complete utilization of the hydride of the reagent for the reduction of organic halides is also of synthetic significance.
Synthesis and Characterization of Hydrazone and Azine Derivatives of Bis(cyclopentadienyl)titanium(IV)
Authors: Khera Brij , Sharma Anand Kumar , Kaushik Narender Kumar
Published: July 2006

Pentacoordinated hydrazone and azine derivatives of bis(cyclopentadienyl)titanium(IV) of the type [(OC6H4CR : NNHR′)TiCl(Cp)2] and [(OC6H4CR″ : NN : CR″C6H4O)Ti(Cp)2], where R=H or CH3, R′=H, C6H5 or C6H3(NO2)2 and R″=H or CH3, have been prepared. The products were characterized by chemical analyses, electrical conductance, IR, 1H NMR, and electronic spectral studies.
Absorption Spectra of Tetrahedral Co(III) and Co(II) Complexes in Heteropolytungstates
Authors: Kojima Kazuo , Matsuda Jiro
Published: July 2006

The absorption spectra of Co(III) and Co(II) in the single crystals of the Keggin-structure compounds, K5[CoIIIW12O40]·nH2O and K6[CoIIW12O40]·mH2O, have been measured at 77 K. The spectra of these complexes in aqueous solutions have also been observed. All the spectra have been interpreted using crystal-field theory by assuming that a Co(III) or Co(II) ion is in Td symmetry. The parameters, Dq, B, and C⁄B can be evaluated as 780 cm−1, 630 cm−1, and 4.7 respectively for the Co(III) complex, and 460 cm−1, 650 cm−1, and 4.5 respectively for the Co(II) complex.
Structure of Cobalt(III) Complexes with (R,R)- and (R,S)-N,N,N′,N′-Tetrakis(2-aminoethyl)-2,4-pentanediamine and N,N,N′,N′-Tetrakis(2-aminoethyl)-1,3-propanediamine
Authors: Ishii Toshio , Ohba Shigeru , Ito Masatoki , Fukushi Sachio , Saito Yoshihiko
Published: July 2006

Crystal structures of the two isomeric Co(III) complexes with sexidentate ligands, (NH2CH2CH2)2NC*H(CH3)CH2C*H(CH3)N(CH2CH2NH2)2 (hereafter abbreviated as R,R- and R,S-tptn) and of the Co(III) complex with a sexidentate ligand, (NH2CH2CH2)2NCH2CH2CH2N(CH2CH2NH2)2 (abbreviated as ttn) were determined by an X-ray diffraction method. The crystal data and the final R factors are: (1) [Co(R,R-tptn)](ClO4)3·H2O, tetragonal, P42212, a=12.800(1), c=15.312(1) Å, V=2509(1) Å3, Z=4, R=0.053 for 1627 observed unique reflections, (2) [Co(R,S-tptn)]Cl3·3H2O, monoclinic, P21⁄a, a=16.778(6), b=14.296(2), c=9.478(4) Å, β=110.99(3)°, V=2123(1) Å3, Z=4, R=0.045 for 3583 reflections and (3) [Co(ttn)]Br3·H2O, trigonal, P\={3}cl, a=14.436(4), c=15.718(9) Å, V=2837(2) Å3, Z=6, R=0.096 for 1183 reflections. The equatorial preference of the methyl groups in the central six-membered chelate ring formed by Co and 2,4-pentanediamine moiety of R,R- and R,S-tptn has been recognized. In (1) the six-membered chelate ring adopts a twist boat form as in (3) with the two C–CH3 bonds in equatorial positions. In (2) the six-membered chelate ring takes a largely flattened chair form with the two C–CH3 bonds again in equatorial positions. The effect of an elongation of the Co–N bond distance on the energy of the first absorption band was discussed.
The Selective N-Monoalkylation of Amides with Alkyl Halides in the Presence of Alumina and KOH
Authors: Sukata Kazuaki
Published: July 2006

The effects of alumina impregnated with KOH (KOH/Al2O3) and a mixture of alumina and powdered KOH (KOH+Al2O3) have been examined using the alkylation of benzamide under various conditions. In each case, alkylation occurs exclusively in the pores of the alumina, the extent depending upon the alumina-pore size. For both yield and selectivity for N-monoalkylation, KOH+Al2O3 is superior to KOH/Al2O3. Dioxane is the best of the solvents employed. It is proposed that, in dioxane, an enolate-like species, (Remark: Graphics omitted.), exists as stable ion-pair aggregates, which are the true reactants in the pore. This method, using KOH/Al2O3 or KOH+Al2O3, has been applied to N-alkylation of the other amides, giving the N-monoalkylated products in substantial yields with extremely high selectivities. 2-Phenylacetamide is regioselectively N-monoalkylated in high yields. This regioselectivity is explained in terms of steric hindrance.
Digital Derivative Spectrophotometric Determination of Micro Amounts of Iron with 1,10-Phenanthroline
Authors: Katsuyama Tetsuo , Shida Junichi
Published: July 2006

Digital first-order derivative spectrophotometry was applied to the determination of iron with 1,10-phenanthroline. Under the recommended conditions, a linear relationship was confirmed between the first-derivative value and the iron concentration. The present method gives accurate results for iron, ranging from 1.6×10−7 to 8×10−5 mol dm−3 (8.9 μg dm−3–4.5 mg dm−3). The relative standard deviations for the determination of 4.8×10−5, 4.8×10−6, and 4.8×10−7mol dm−3 of iron(III) were 0.37, 0.38, and 0.93%, respectively. The effects of 63 diverse ions were examined. The present method was applied to the determination of iron in practical samples, i.e., river water, waste water and sea water.
The Synthesis and X-Ray Structure of (l- or d-Alanine-N-acetato)(l-histidinato)chromium(III)
Authors: Sato Mitsunobu , Kosaka Masao , Watabe Masatoshi
Published: July 2006

The (l-alanine-N-acetato)(l-histidinato)chromium(III) monohydrate complex, C11H14N4O6Cr, has been synthesized and its crystal structure has been determined from three dimensional X-ray-diffractometer data. The crystals are orthorhombic, of the space group P212121, with 4 molecules in a cell with these dimensions: a=11.052(1), b=13.959(3), and c=9.616(2) Å. Block-diagonal least-squares refinements using 1318 independent nonzero reflections have yielded a conventional R factor of 0.033. The structure consists of monomeric [Cr(l-alama)(l-his)] units and water molecules. The l-alama ligand coordinates to the metal as of dianion, with Cr–O(acetyl), Cr–N, and Cr–O(alanine) bond lengths of 1.960(3), 2.078(5), and 1.946(4) Å respectively. The histidinate monoanion coordinates through Cr–N(amino), Cr–N(imidazole), and Cr–O bonds 2.062(4), 2.036(5), and 1.957(4) Å long respectively. The geometry at chromium is a distorted octahedron, with cis bond angles in the range from 80.1(2) to 99.3(2)°. Among the six possible isomers of the [Cr(l-alama)(l-his)] complex, only one isomer was prepared and crystallized; its geometry was r-l-trans(O)cis(N).
Solvent Extraction of Mercury(II) from Hydrochloric Acid with 1,2-Bis(hexylthio)ethane
Authors: Baba Yoshinari , Ikeda Yutaka , Inoue Katsutoshi
Published: July 2006

Solvent extraction of mercury(II) from hydrochloric acid with 1,2-bis(hexylthio)ethane (=BHTE=\barS) in 1,2-dichloroethane has been studied at 30 °C. Mercury(II) was found to be extracted into pure 1,2-dichloroethane without extractants, which is due to the physical partition of the neutral species, HgCl2. The partition coefficient, KD, was evaluated as KD=0.314. It was clarified that the extraction mechanism with BHTE can be explained in terms of solvation by BHTE and that 1:1 metal: the ligand complex is formed in the organic phase as follows.

\barS+HgCl2\ightleftharpoons‾HgCl2·S  Ke

The extraction equilibrium constant, Ke, was evaluated as Ke=1.61×103 dm3 mol−1.
The Short Range Structure of Ion-polar Solvent Mixtures. Calculations by the RISM Integral Equations
Authors: Ohba Masaharu , Arakawa Kiyoshi
Published: July 2006

The reference hypernetted chain like integral equation of the interaction site model is solved numerically for a solution of ions in a polar solvent. In our model, the ions and the solvent molecules are taken to be charged hard spheres and polar hard dumb-bells, respectively. Calculated pair correlation functions contain a great deal of interesting information on the short range structure of the ionic solutions: a solvated structure around ions and an effect of ionic charges upon the structure of the solvent. It is found that various types of associated structures of constituent species, such as simple ion pairs, ion triplets, and ion pairs separated by one solvent molecule exist in ionic solutions.
Catalytic Activity of Copper(II) Salt of Heteropolyphosphoric Acid for the Reduction of NO with Its Supporting Active Carbon
Authors: Mochida Isao , Yata Kiyoshi , Fujitsu Hiroshi , Komatsubara Yoshinobu
Published: July 2006

The catalytic activity of a copper(II) salt of polymolybdophosphoric acid (Cu1.1H0.8PA) for the reduction of NO with the supporting active carbon into N2 and N2O was studied at 400 °C using a fixed bed flow reactor. A considerable activity was observable at a stationary state where the spill-over of oxygen left on the active site of the acid to the carbon surface appeared to be rate-determining. The activity of the salt was much higher than for component oxides produced through its decomposition at higher temperatures. This suggested that the active site was characteristic to the salt (very probably the reduced site in the salt). The reaction mechanism in terms of the reaction paths, the N2O/N2 selectivity, and the roles of the supporting active carbon are discussed based on kinetic investigations.
Identification of the Adsorbate Formed on a Platinum Electrode from Methanol
Authors: Matsui Hiroshi , Hisano Takeo , Terazawa Toshio
Published: July 2006

The kind of carbon-containing adsorbate formed on a platinum electrode from methanol in an acid medium was identified by an electrochemical method. Certain improvements were made in view of the harmful effects of the following factors on the QF value, the quantity of electricity required to form adsorbate. The factors: a) The amounts of dissolved oxygen in both solution and electrode itself; b) the concurrent oxidation of the adsorbate in the adsorption process; and c) the presence of by-products of the methanol oxidation, formaldehyde and formic acid. By appropriate procedures, these effects could be minimized or corrected. The ratio QF⁄Qox, where Qox was an electric quantity required to oxidize completely that amount of adsorbate corresponding to the QF, was found to be 1.8–2.0 when the potential was 0.30–0.54 V, and the methanol concentration 0.005–1 mol dm−3. It was thus concluded that the adsorbate was almost exclusively COad.
A Relation between Oxidation State of Sulfur and Acidic Property of Iron Oxide Containing Sulfur
Authors: Nagase Yoshinori , Jin Tuo , Hattori Hideshi , Yamaguchi Tsutomu , Tanabe Kozo
Published: July 2006

Five kinds of iron oxide catalysts promoted with sulfur were prepared by impregnating Fe(OH)3 with (NH4)2SO4 and by treating Fe2O3 and Fe(OH)3 with H2S and SO2. Changes in acidic properties of the catalysts with changes in oxidation states of sulfur were investigated by test reactions such as isomerization of cyclopropane and dehydration of 2-propanol over the oxidized or reduced catalysts. It has been found that the generation of acidic properties of the catalysts was independent of the kinds of the starting sulfur compounds, but dependent on the oxidation states of the sulfur. The sulfur in the highest oxidation state was responsible for the strongly acidic property of the catalyst.
Studies on Salt Hydrates for Latent Heat Storage. VII. The Relation between Activation Process of Crystal Nucleation Catalysts for Sodium Acetate Trihydrate and Their Deactivation Temperatures
Authors: Wada Takahiro , Yoneno Hiroshi
Published: July 2006

Influences of preheating temperature were studied on crystallization of CH3CO2Na·3H2O from its melts containing a small amount of Na4P2O7 or Na2HPO4 as a crystal nucleation catalyst. The relation between the activation process of these nucleation catalysts and their deactivation temperatures was investigated in detail. Aging of nucleation catalyst which was preceded by forced crystallization of CH3CO2Na·3H2O from its melt containing the catalyst, largely affects the catalyst’s deactivation temperature. Whenever Na4P2O7 or Na2HPO4 was used as a nucleation catalyst, the deactivation temperature was raised by lengthening aging time at a constant aging temperature. When the catalysts were aged for 4 d at 20 °C, the aging effect on them was almost saturated. At lower temperatures, longer aging times were required for saturation of the effect. The results obtained are discussed with a modified adsorption model, which takes into account commensurate-incommensurate phase transition of solid adsorbate.
Resonance Raman and 129I Mössbauer Spectroscopic Study of Iodine Doped in Poly(thienylene)s
Authors: Sakai Hiroshi , Mizota Manabu , Maeda Yutaka , Yamamoto Takakazu , Yamamoto Akio
Published: July 2006

Resonance Raman and 129I Mössbauer spectroscopy have been used in a study of iodine doped poly(thienylene)s, which are chemically synthesized by the polymerization of dibromothiophenes. It is shown that the iodine species in the polymers are present predominantly in the form of a polyiodide which consists of unsymmetrical I3− and I2 units. That is, the iodine molecule doped is reduced by taking electrons from the polymer in a similar manner to iodine doped in polyacetylene. This result is consistent with the fact that poly(thienylene)s undergo an increase in electrical conductivity upon doping with iodine.
Solvation and Protonation of 1,10-Phenanthroline in Aqueous Dioxane Solutions
Authors: Ishiguro Shin-ichi , Wada Hideo , Ohtaki Hitoshi
Published: July 2006

Solvation and protonation of 1,10-phenanthroline (phen) have been studied by potentiometry and calorimetry in various aqueous dioxane solutions. Protonation reactions were studied in the mixtures (the dioxane content x=0–0.4 mole fraction) containing 0.3 mol dm−3 NaCl as a constant ionic medium at 25 °C. Potentiometric and calorimetric titration curves obtained in the range of −log[H+]=2–7 were well explained in terms of the formation of Hphen+ and H(phen)2+, and the formation constants, enthalpies and entropies of formation of the species were determined. The formation constants of the both species gradually decreased with increasing x, and then the formation of H(phen)2+ became negligibly small at x>0.1, while the enthalpy and entropy of formation of Hphen+ first decreased and then increased with increasing x and thus minima were found at x=0.05. Enthalpies of solution of anhydrous 1,10-phenanthroline were also determined in both neutral (x=0–1) and acidic (0.1 mol dm−3 HCl, x=0–0.4) aqueous dioxane solutions. By knowing enthalpies of solution of 1,10-phenanthroline in acidic solutions and of formation of Hphen+ in the mixed solvents, enthalpies of solution of 1,10-phenanthroline in neutral solutions (ΔH°s(phen)) were evaluated and compared with those directly obtained in the neutral solutions (ΔH°s,neutral). A significant difference was found between ΔH°s(phen) and ΔH°s,neutral in the range x<0.3, which could be ascribed to the formation of stacked species of 1,10-phenanthroline molecules, (phen)n. The variation of ΔH°s(phen) with x was explained in terms of the enhanced solvation of dioxane to phenanthroline molecules owing to breaking of the hydrophobic water structure around them. Solvent effects on the formation of Hphen+ and H(phen)2+ were discussed in terms of different solvation behavior of 1,10-phenanthroline and proton with x.
Oxygen-17 NMR Study of the Uranyl Ion. II. Correlation between 17O NMR Chemical Shifts and Wavelengths of UV-Visible Absorption Bands of Uranyl Complexes
Authors: Jung Woo-Sik , Tomiyasu Hiroshi , Fukutomi Hiroshi
Published: July 2006

17O NMR chemical shifts, UV-visible and IR spectra of a series of [UO2Ln](ClO4)2 (L=unidentate oxygen-donor ligand; n=coordination number) complexes in nonaqueous solvents have been measured. The electronic transition bands of the UO22+ entity shift toward lower energies with the increase in base strength of ligands in the equatorial plane. The asymmetric stretching frequencies of U=O bands are also affected by the base strength of equatorial ligands and correlated with the lowest electronic transition energies of uranyl complexes with the same geometry. The 17O chemical shifts are shown to be related to the lowest electronic transition energies of uranyl complexes. It appears that oxygen isotope shifts in 17O NMR spectra of the uranyl ion are predominantly attributed to the increase in the lowest electronic transition energies.
Phase Equilibria in the Ln2O3–V2O3–V2O5 (Ln=Pr, Tb, and Y) Systems at 1200 °C
Authors: Kitayama Kenzo , Katsura Takashi
Published: July 2006

The phase equilibria in the systems, Pr2O3–V2O3–V2O5, Tb2O3–V2O3–V2O5, and Y2O3–V2O3–V2O5, were established at 1200 °C by changing the oxygen partial pressure from −1.20 (in the CO2) to 7.50 in −log (PO2/Pa) for Pr2O3 and Tb2O3 systems, and from −4.32 (in the air) to 7.50 in −log (PO2/Pa) for Y2O3 system. In the first system 0.81Pr2O3·0.19V2O5(A) and 3Pr2O3·V2O5(B), in the second 0.81Tb2O3·0.19V2O5(A′), and in the last one 4Y2O3·V2O5(A″) were stable in addition to Ln2O3, LnVO4, LnVO3, VnO2n−1 (n=2–7, and Ln means Pr, Tb, and Y), and VO2 under the present experimental conditions. On the basis of the established phase diagrams, the standard Gibbs energies (ΔG°) of reactions appeared in the systems were calculated. Compounds A, B, PrVO3, A′, A″, and LnVO4 have nonstoichiometric compositions. ΔG° values for the reactions and crystallographic values of the compounds were represented as a function of the ionic radius of lanthanoid (including Y) elements.
Electrocatalytic Oxidation of Chlorpromazine in Phosphate Solution
Authors: Takamura Kiyoko , Inoue Satoshi , Kusu Fumiyo , Oyama Noboru
Published: July 2006

The kinetics of electrocatalytic oxidation process of chlorpromazine (CPZ) at a pyrolytic graphite electrode in a phosphate solution was investigated by rotating disk voltammetry. The reactions involving regeneration process of CPZ through the disproportionation of reaction intermediates are proposed and the rate constants of the chemical reaction (kobsd), following the electrochemical oxidation of CPZ to the CPZ cation radical, were evaluated from the electrode rotation-rate dependence of the limiting currents obtained in the CPZ solution with and without phosphate. The proportional relations between the logarithm of kobsd and pH, and between kobsd and the concentration of H2PO4− were obtained.
Calorimetric and Raman Spectroscopic Studies on Formation of Cadmium(II) Thiocyanato Complexes in Aqueous Solution
Authors: Ishiguro Shin-ichi , Yamamoto Kiyoshi , Ohtaki Hitoshi
Published: July 2006

Complex formation equilibria between cadmium(II) and thiocyanate ions have been calorimetrically studied at 25 °C in aqueous solution containing NaClO4 in order to keep 3 mol dm−3 ionic strength in the test solutions. Calorimetric titration curves thus obtained were well explained in terms of formation of dinuclear [Cd2X]3+ (X=SCN) and mononuclear [CdXn](2−n)+ (n=1–4) complexes, and their formation constants, enthalpies and entropies were determined. The stepwise enthalpy and entropy values at the third consecutive step were largely positive, indicating that water molecules solvating Cd(II) ion were extensivelyl liberated at this step. It was thus suggested that the coordination symmetry around Cd(II) ion changed from octahedral to tetrahedral at the formation of [CdX3]−. Raman spectra of the C–S and C–N stretching vibrations of SCN− ion were measured in cadmium(II) thiocyanate solutions with varying molar ratios of the metal to ligand ions. It was shown that SCN− ion coordinated to Cd(II) ion through the N atom at the first step of the complex formation, and the S atom at the second, N at the third and then S at the last. The suggested bonding type of SCN− ion with Cd(II) ion within each cadmium(II) thiocyanato complex was supported by the thermodynamic data.
Synthesis of Aspartyl Pentapeptide Esters in Relation to Structural Features of Sweet Peptides
Authors: Ariyoshi Yasuo
Published: July 2006

A series of seven analogues of aspartyl pentapeptides has been synthesized in relation to the structural features of sweet peptides. The rule in the structure-taste relationships of di-, tri-, and tetrapeptides is inapplicable to the pentapeptides. All the pentapeptides were devoid of sweetness, though they satisfied the requirements for sweet peptides. The result indicates that oligopeptides can not fit a deep receptor pocket. The mode of interactions between sweet peptides and the receptor is drawn schematically.
Synthesis and Characterization of Macrocyclic Polyaza(2,5)pyridinophanes Possessing Vitamin B6 Functionality
Authors: Iwata Masaaki , Kuzuhara Hiroyoshi
Published: July 2006

Series of macrocyclic polyaza[m](2,5)pyridinophanes (poly=tri, tetra, penta; m=9, 12, 15)(8–10) and polyaza[m]paracyclophanes (11–13) were synthesized in excellent yields by the reaction of dichloropyridoxine derivatives (4) and α,α′-dibromo-p-xylene (5), respectively, with a series of 1,2-ethanediamine derivatives (1–3). These phanes were characterized on the basis of 1H NMR spectra. The methyl group at C6 of the pyridoxine moiety (a-series) revealed restricted rotation for all bridge sizes (m=9–15). In 8–10 without the methyl group (b-series), m=12 was the boundary between restricted and free rotation. In series 11–13, only 11 (m=9) showed restricted rotation. Atomic group equivalence was discussed in terms of boundary restricted rotation and an empirical rule for the prediction of the relationship between the bridge size and restricted rotation was proposed.
An Electric-Field-Pulse Relaxation Study of the Electron-Donor-Acceptor Complex Formation Involving 7,7,8,8-Tetracyanoquinodimethane Solubilized at the Surfactant Bilayer/Magnetite Particle Interface
Authors: Ikeda Tetsuya , Harada Shoji , Yasunaga Tatsuya
Published: July 2006

Ultrafine magnetite particle (Fe3O4) which adsorbed the 7,7,8,8-tetracyanoquinodimethane (TCNQ)dioctadecyldimethylammonium bromide (DODAB) bilayer on the surface were prepared in an aqueous solution by sonication. A single relaxation was found by using the electric-field-pulse method and was attributed to the association-dissociation process of the electron-donor-acceptor complexes involving TCNQ solubilized at the DODAB bilayer/magnetite particle interface.
Molecular Motion in GeCl4 as Studied by 35Cl Nuclear Quadrupole Resonance
Authors: Nakayama Hirokazu , Nakamura Nobuo , Chihara Hideaki
Published: July 2006

Temperature dependence of 35Cl nuclear quadrupole resonance frequencies and quadrupole relaxation time was measured of GeCl4 in the metastable phase. Above 160 K, molecular reorientation is seen active; its activation energy is 63.5 kJ mol−1. This energy probably prevents GeCl4 from undergoing a rotational phase transition.
Molecular Complexes of N,N,N′,N′-Tetraisopropyloxamide. Crystal Structures of Its 1:1 Adduct with m-Cresol, and Its 1:1 and 1:2 Adducts with p-Cresol
Authors: Toda Fumio , Tagami Yasunori , Mak Thomas C W
Published: July 2006

The crystal structures of a 1:1 complex (I) of N,N,N′,N′-tetraisopropyloxamide with m-cresol, a 1:1 complex (II) with p-cresol, and a 1:2 complex (III) with p-cresol have been determined by X-ray crystallography. The crystal data are: I, C21H36N2O3, P21⁄c, a=12.104(4), b=6.860(3) c=27.186(8) Å, β=93.46(2)°, Z=4, and RF=0.093 for 1661 observed Mo Kα data; II, C21H36N2O3, P21⁄n, a=7.825(2), b=11.379(4), c=25.39(1) Å, β=91.01(2)°, Z=4, and RF=0.105 for 1326 data; III, C28H44N2O4, C2⁄c, a=11.744(3), b=10.658(2), c=23.576(4) Å, β=102.07(2)°, Z=4, RF=0.045 for 1382 data. The stoichiometric formulas faithfully represent the structures of all three complexes, with each phenolic OH group forming a donor hydrogen bond to an O atom of the oxamide host molecule.
Photochemical Hydroxymethylation of Alicyclic and Aliphatic Alkenes Induced by a EuIII/EuII Photoredox System in Methanol
Authors: Ishida Akito , Yamashita Shinya , Toki Susumu , Takamuku Setsuo
Published: July 2006

The photoirradiation of a methanol solution of EuCl3 and alkenes such as cyclohexene, cyclooctene, cyclododecene, and tetramethylethylene afforded (hydroxymethyl) alkane. The dihydro dimer of alkene, hydrogen, and ethylene glycol are also formed. Reactions proceed via a radical mechanism induced by hydrogen atoms and hydroxymethyl radicals, which are produced by a photoredox reaction of EuIII/EuII in methanol.
Syntheses of Cyclic Decapeptides with Four Ornithyl Residues Related to Gramicidin S
Authors: Ando Setsuko , Nishikawa Hiroshi , Takiguchi Hideo , Izumiya Nobuo
Published: July 2006

Three cyclic decapeptides with four l-ornithyl residues related to gramicidin S (GS), cyclo(–Orn–Leu–Orn–d-Phe–Pro–)2 (D-L-12), cyclo(–Orn–Leu–Orn–Phe–Pro–)2 (L-L-12), and cyclo(–Orn–Leu–Orn–Phe–d-Pro–)2 (L-D-12), were synthesized to investigate the contribution of increase of the basic amino acid residues and of configurations of phenylalanyl and prolyl residues toward antibacterial activity. These GS-like analogs were synthesized by the solution method of peptide synthesis. Protected cyclic decapeptides were synthesized through a cyclization reaction of linear decapeptide azide in pyridine. Hydrogenolysis of the protected cyclic decapeptides afforded crystalline tetrahydrochlorides of the desired analogs. In the experiment of circular dichroism, D-L-12 gave a curve similar to that of GS, while L-L-12 and L-D-12 gave different curves. Antibacterial assays showed L-L-12 exhibited substantial activities against Gram-negative bacteria, whereas D-L-12 and L-D-12 negligible activity.
Spectrophotometric Determination of Micro-Amounts of Ruthenium(III) and Platinum(IV) with Acenaphthenequinone Mono(thiosemicarbazone)
Authors: Singh Shailendra Kumar , Sharma Rakesh Kumar , Sindhwani Sharwan Kumar
Published: July 2006

Ruthenium(III) and platinum(IV) form 1:2 (metal:ligand) complexes with acenaphthenequinone mono(thiosemicarbazone) (AQTS). The complexes are soluble in 70% N,N-dimethylformamide (DMF). The reagent has been used for the spectrophotometric determination of Ru(III) and Pt(IV). The optimum ranges of concentration for the determination of Ru(III) and Pt(IV) are 2.02–7.09 and 2.83–11.6 ppm over the pH range 5.3–6.8 and 1.9–4.1, respectively. The Sandell sensitivities for the determination of Ru(III) and Pt(IV) are 0.01 and 0.016 μg cm−2, respectively. The determination has also been carried out in the presence of foreign ions.
The Structure of Diaquatetrakis(thiocyanato)cobalt(II)mercury(II)-N-Methyl-2-pyrrolidone(1/2), CoHg(SCN)4(H2O)2·2(C3H6CONCH3)
Authors: Kinoshita Hisashi , Shimoi Mamoru , Ouchi Akira
Published: July 2006

The crystal and molecular structure of the title complex was determined using the single-crystal X-ray diffraction method. A crystal of CoHgC14H22N6O4S4, F.W. 726.15, is tetragonal with a space group P\bar4, a=12.082(3), c=8.097(2)Å, U=1182.0(5)Å3, Z=2, Dx=2.04 Mg m−3, and μ(Mo Kα)=7.72 mm−1. Tetrahedral mercury(II) coordinated with four sulfur atoms and octahedral cobalt(II) coordinated with four nitrogen atoms of SCN− (equatorially) and two oxygen atoms of H2O (axially) are linked by thiocyanate bridges to form planar networks parallel to (001). The planes are connected by N-methyl-2-pyrrolidone (mpd) molecules through the hydrogen bonds with two coordinated water molecules at both side networks. The structure resembles that of the N,N-dimethylacetamide (dma) adduct, CoHg(SCN)4(H2O)2·2dma. These are new types of inclusion compounds.
Acid Dissociation Constants of Dialkyldithiocarbamic Acids and O,O′-Dialkyl S-Hydrogen Dithiophosphates and Formation Constants of Their Complexes with Cadmium(II), Zinc(II), and Lead(II) in 1:1 v/v Water-DMF Medium
Authors: Hayashi Kenjiro , Sasaki Yoshiaki , Tagashira Shoji , Yanagidani Takagimi
Published: July 2006

The log values of β3, the formation constants of metal complexes with dialkyldithiocarbamates and O,O′-dialkyl dithiophosphates, were determined by polarography. The pKa values, the acid-dissociation constants of these ligands, were also determined kinetically. A linear relationship exists between these two variables for each metal and straight parallel lines were obtained.
Metal Complexes of Octabutyl- and Octaoctylporphyrins Preparation and Properties
Authors: Ye Chang Quing , Tsuruta Haruki , Otsuka Sei
Published: July 2006

Octabutyl- and octaoctylporphyrin complexes of FeII, CoII, NiII, and CuII ions were prepared as a family of highly lipophilic metalloporphyrins.
The Effect of Intermolecular Association on Kinetic Behavior. Rate Acceleration with Time in Oxidation of a Pair of Thiols
Authors: Ito Masato M , Ogikubo Toshikazu , Ueda Hideki , Hagino Kazuomi , Endo Tadashi
Published: July 2006

In base-catalyzed oxidation of a pair of associating thiols [HSCH2–CONHCONH–Ph and HSCH2CH2–NHCONHCO–C6H13], rate enhancement with time occurred in protic media, whereas the rate was reduced with time in aprotic solvents. For a pair of nonassociating thiols [HSCH2CO2C2H5 and HSCH2CH2OH], the rate enhancement was neither observed in a protic solvent nor in an aprotic one.
A New Synthesis of α-Phenylhomoallylnitriles from β-Nitrostyrene and Allylic Silanes
Authors: Uno Hidemitsu , Fujiki Satomi , Suzuki Hitomi
Published: July 2006

TiCl4-catalyzed addition of allylic silanes to β-nitrostyrene affords γ,δ-unsaturated nitronates which, on treatment with low valent titanium in situ generated from Ti(IV) and zinc, are smoothly converted to γ,δ-unsaturated nitriles in moderate yields.
Synthesis and Chiral Recognition of Optically Active Crown Ethers Incorporating a 9,9′-Biphenanthryl Moiety as the Chiral Center
Authors: Yamamoto Koji , Kitsuki Tomohito , Okamoto Yoshio
Published: July 2006

Two chiral crown ethers incorporating a 9,9′-biphenanthryl moiety as the chiral center have been prepared, and their chiral recognition properties in transport of methyl (±)-phenylglycinate hydrochloride, (±)-1-phenylethylamine hydrochloride, and (±)-1,2-diphenylethylamine hydrochloride were examined.
Crystal Structure and Physical Properties of (TTM-TTF)I2.47
Authors: Wu Peiji , Mori Takehiko , Enoki Toshiaki , Imaeda Kenichi , Saito Gunzi , Inokuchi Hiroo
Published: July 2006

The X-ray crystal structure analysis of a novel organic conductor (TTM-TTF)I2.47 (TTM-TTF: tetrakis(methylthio)tetrathiafulvalene) shows that the donors with an almost flat structure are stacked face-to-face to form columns. The iodine lattice composed of I3− columns is incommensurate with the donor lattice. The measurements of resistivity, thermoelectric power, and ESR show a metal-insulator transition around 100 K. This transition is attributed to the Peierls type phase transition. The quasi-one-dimensional electronic structure is supported by the arrangement of the donor molecules in the crystal and the calculated anisotropy of transfer integrals.
Synthesis and Characterization of Lanthanoid Complexes with 1,3-Bis(2-pyridylmethyleneamino)-2-propanol
Authors: Sakamoto Masatomi
Published: July 2006

Lanthanoid complexes of a general formula [Ln(appy)(NO3)2]H2O (Ln=La, Pr, Nd, Eu, or Gd) have been synthesized with 1,3-bis(2-pyridylmethyleneamino)-2-propanol (Happy). The complexes were characterized to be mononuclear and of nine-coordination in solid state with quinquedentate appy− and two bidentate NO3− ions. On dissolution in dimethyl sulfoxide, the complexes were shown to dissociate into [Ln(appy)(dmso)n]2+ based on 13C-NMR spectra and molar conductance measurements.
Asymmetric Oxidation of Sulfides with Optically Active Hydroperoxides Prepared by Singlet Oxygenation of Thiazolidine Derivatives
Authors: Takata Toshikazu , Ando Wataru
Published: July 2006

Asymmetric oxidation of prochiral sulfides with optically active hydroperoxides prepared in situ by photo-sensitized oxygenation, gives chiral sulfoxides with moderate optical yields which are enhanced by addition of Ti(OPri)4.
2-Allylisourea as a Starting Material for Palladium-Catalyzed Wittig-Type Allylidenation of Aldehydes
Authors: Inoue Yoshio , Toyofuku Masanori , Hashimoto Harukichi
Published: July 2006

2-Allylic-substituted isoureas underwent Wittig-type allylidenation of aldehydes in the presence of triphenylphosphine and 2 mol% of [Pd(PPh3)3] to give the corresponding conjugated olefins in tolerable to good yields.
On the Synthesis of Crystalline and Semicrystalline Tin(IV) Selenophosphate
Authors: Nabi Syed Ashfaq , Siddiqi Zia Mahmood
Published: July 2006

Samples of tin(IV) selenophosphate have been synthesized by mixing 0.05 M (1 M=1 mol dm−3) aqueous solutions of tin(IV) chloride, sodium selenite, and sodium dihydrogenphoshate in different volume ratios and at different pH. A crystalline and a semicrystalline products are obtained when the precipitates are refluxed. Ion-exchange behavior of refluxed product is compared with the unrefluxed one.
Hydrogen Bonding in Polyfluoride Ions
Authors: Kar Tapas , Sannigrahi Abani Bhusan
Published: July 2006

Hydrogen bonding in the polyfluoride ions (HnFn+1−, n=1 to 4) has been discussed in the light of atomic charges, bond ionicities, valencies and bond indices calculated from CNDO/2 wave functions. The hydrogen-bond energy in these ions is found to bear a qualitative relation with the bond index of the hydrogen bond.
A New Aspect of the Pressure Effect in Syngas Conversion to Ethylene Glycol
Authors: Masuda Takashi , Murata Kazuhisa , Matsuda Akio
Published: July 2006

Pressure effect in syngas conversion to ethylene glycol (EG) is understood in terms of respective partial pressures of hydrogen (PH2) and carbon monoxide (PCO). A new mechanism is proposed to explain an extraordinary effect of PH2 on the selectivity to EG.
Preparation and Stereochemistry of (Acetylacetonato)(2,2′-bipyridine)chromium(III) Complexes with 2,2′-Bipyridine N,N′-Dioxide or Its 3,3′-Dimethyl Derivative
Authors: Kanno Hideaki , Utsuno Shunji , Fujita Junnosuke
Published: July 2006

Four new mixed-ligand chromium(III) complexes, [Cr(acac)(bpy)(L)]2+ and [Cr(bpy)(phen)(L)]3+, where L denotes a seven-membered chelate ligand, 2,2′-bipyridine N,N′-dioxide (bpdo) or its 3,3′-dimethyl derivative (mbdo), were prepared and resolved. All of the complexes formed only one of two possible racemic pairs of diastereomers. The pair was assigned to have an ob(Δ(δ), Λ(λ)) structure on the basis of the circular dichroism spectra and the absolute configuration of optically active mbdo recovered from the resolved complex.
Linear Furano Compounds: Synthesis of 7H-Furo[3,2-g][1]benzopyran-7-ones
Authors: Geetanjali Y , Rajitha B , Rao M Kanakalingeswara
Published: July 2006

A novel synthesis of 2-aroyl-7H-furo[3,2-g][1]benzopyran-7-ones, viz., IIIa and b was reported by condensing 2-benzoyl- and 2-(p-methoxybenzoyl)-3-methyl-5-acetyl-6-hydroxybenzofuran (Ia and b) with C6H5CH2COONa-Ac2O. VI was synthesised by condensing 7-hydroxy-6-benzoyl-4,8-dimethylcoumarin (IV) with V. The basic ethers (IIId–j) were synthesised by demethylating IIIb with pyridinehydrochloride and resultant IIIc was condensed with N,N-dialkyl-2-haloalkanamine hydrochlorides. UV, IR, 1H NMR, and Mass spectral data are also given.
129I Mössbauer Spectroscopic Studies on the Iodine Complexes of N,N′-Diphenyl-p-phenylenediamine and N,N′-Diphenylbenzidine
Authors: Sakai Hiroshi , Maeda Yutaka
Published: July 2006

129I Mössbauer and resonance Raman spectroscopy have been applied to the iodine complexes of N,N′-diphenyl-p-phenylenediamine (DPPD–I2.4) and N,N′-diphenylbenzidine (DPB–I2.7), which exhibit relatively high electrical conductivities. The Mössbauer spectra of these complexes indicate the existence of two unequivalent iodine sites, corresponding to the central and terminal iodine atoms of a linear I3− unit. The resonance Raman spectra suggest that the I3− unit exists as a successive chain in these complexes. This is consistent with the crystallographic data of the DPPD–I2.4 complex. The charge density of the I3− unit is slightly different from that of the isolated I3− ion because of a weak covalent bond between I3− units. It is confirmed that both complexes are partially oxidized mixed-valence compounds, formulated as (DPPD)+0.8 (I3−)0.8 and (DPB)+0.9 (I3−)0.9.
Intramolecular “Diene-Regenerable” Diels–Alder Reaction of 2-Pyrone-6-carboxamides. Preparation and Reaction of Fused 1,3-Cyclohexadiene Systems
Authors: Noguchi Michihiko , Kakimoto Shinji , Kawakami Hisao , Kajigaeshi Shoji
Published: July 2006

The 2-pyrone-6-carboxamides, prepared from 2-pyrone-6-carbonyl chloride and substituted allylamine, undergo an intramolecular Diels–Alder reaction spontaneously to give 3a,4,5,7a-tetrahydro-1-oxoisoindoline-5,7a-carbolactones, which regenerate the diene moieties by the decarboxylation to afford 3a,4-dihydro-1-oxoisoindolines. 3a,4,4a,5-Tetrahydro-1(2H)-isoquinolone and 2,3,4,5,5a,6-hexahydro-1H-2-benzazepin-1-one derivatives are obtained similarly from the corresponding amides. These fused 1,3-cyclohexadiene systems reveal to be versatile synthetic intermediates for polycyclic compounds by cycloaddition reaction and for benzo-fused heterocycles by dehydrogenation. The stereochemistries in the successive cycloaddition reactions are also discussed.
From Penicillin to Penem and Carbapenem. VIII. Introduction of an Allyl Group at the C-4 Position of the Azetidinone Molecule, and the Synthesis of Dethiathienamycin
Authors: Fujimoto Katsumi , Iwano Yuji , Hirai Koichi
Published: July 2006

A new C3-unit introduction reaction at the C-4 position of 4-acetoxy-2-azetidinone derivatives using tetraallyltin in the presence of 1/10 equiv of boron trifluoride etherate in dichloromethane is described. Dethiathienamycin was synthesized from (3S,4R)-4-allyl-3-[(R)-1-(t-butyldimethylsilyloxy)ethyl]-2-azetidinone via the ylide intermediate.
A Revised Primary Structure of Neocarzinostatin Using the Combination of Endopeptidase, Carboxypeptidase Y and Fast Atom Bombardment Mass Spectrometry
Authors: Hirayama Kazuo , Ando Toshihiko , Takahashi Rei , Murai Asao
Published: July 2006

The amino acid sequence of antitumor protein neocarzinostatin was revised and confirmed on the basis of mass spectrometric studies. Fast atom bombardment mass spectrometric experiments on neocarzinostatin and its tryptic, chymotryptic, staphylococcal protease, and carboxypeptidase Y digested peptides gave the molecular weights of various peptides and, in some cases, partial sequence information. These experiments gave a revised sequence, Glu(105)–Pro(106) to Pro(105)–Glu(106) and Asp(60) to Asn(60). The peptide fragments produced by these endopeptidase cleavage completely covered the full sequence of neocarzinostatin. Thirty-five of the 113 amino acids were determined by the carboxypeptidase Y digestion.
Nature of Substituent Effect of Nitro and Methoxyl Group on Photocycloaddition of Polymethylene Dicinnamates
Authors: Kuzuya Masayuki , Yokota Naohisa , Noguchi Akihiro , Okuda Takachiyo
Published: July 2006

The nature of the nitro substituent effect and topotactic assistance by the polymethylene chain of polymethylene dicinnamates upon the rate of photocyclization and the stereochemistry of photoproducts have been explored, in comparison with the similar effect of a methoxyl substituent; a striking rate enhancement and stereospecificity of the photoproduct were observed on a trimethylene dicinnamate derivative. However, the detailed study of the stereochemical course of the photoproduct has revealed that the dependence of the topotactic assistance of nitro derivatives on the polymethylene chain length largely differs from that of methoxy derivatives. Based on the results of the CNDO/S-CI excited state calculation of the model compounds, it is concluded that the acceleration character of the nitro substituent is mainly due to the odd electron density at the reaction site, i.e. the olefinic double bond; it is not due to the facile exciplex formation on the excited singlet state, unlike that of a methoxyl substituent.
Kinetic and Equilibrium Studies of Complex Formation of Nickel(II) with Carboxylate Ligands at High Pressure. III. Nickel(II) Malonate and Nickel(II) Tartronate
Authors: Kojima Kiyotaka , Inoue Tohru , Izaki Michiko , Shimozawa Ryosuke
Published: July 2006

Kinetic and equilibrium measurements were carried out for the complexation reaction of nickel(II) malonate and nickel(II) tartronate in an aqueous solution at 20 °C and at pressures up to 100 MPa. The reaction volume, ΔV0, and the activation volume, ΔVf*, for the complex formation were estimated from the pressure dependence of the stability constant and the rate constant. The results are as follows: ΔV0=13.5±1.0 cm3 mol−1 and ΔVf*=14.7±0.5 cm3 mol−1 for nickel(II) malonate, and ΔV0=13.3±0.7 cm3 mol−1 and ΔVf*=15.2±0.5 cm3 mol−1 for nickel(II) tartronate. The larger ΔV0 value compared with those obtained for dicarboxylate ligands which form a monodentate complex coincides with that malonate and tartronate form a chelate complex with nickel(II) in an aqueous solution. By appropriately estimating the volume changes associated with the outer-sphere complex formation and first-bond formation, the overall volume profile for the complexation reaction was obtained. A Similar feature regarding the volume profile for the complexation of nickel(II) malonate and nickel(II) tartronate suggests that tartronate forms a bidentate chelate complex by two carboxyl groups rather than by carboxyl and hydroxyl groups.
Synthesis of 6-Amino-6-deoxy-l-idopyranosides
Authors: Matsuda Keiji , Tsuchiya Tsutomu , Torii Takahiro , Umezawa Sumio
Published: July 2006

Methyl 6-amino-6-deoxy-α- and -β-l-idopyranosides have been prepared from 3-O-acetyl-1,2-O-isopropylidene-d-glucofuranose via 5,6-anhydro-1,2-O-isopropylidene-l-idofuranose and the azide product derived from it. Isopropyl 6-amino-6-deoxy-α- and -β-l-idopyranosides were prepared from 6-azido-2,3,4-tri-O-benzyl-6-deoxy-α-l-idopyranosyl chloride and 2-propanol. Nonprotected α- and β-l-idopyranosides were distinguished by their J1,2 proton couplings.
New Synthesis and Some Reactions of Vinyl Arenecarbodithioates. Wittig Reaction of (Triphenylphosphonio)methyl Arenecarbodithioate Iodides
Authors: Ishida Masaru , Kaga Koh-ichi , Sato Hiroyuki , Yokoi Masato , Kato Shinzi
Published: July 2006

Wittig reaction of new phosphonium salts, (triphenylphosphonio)methyl arenecarbodithioate iodides, with variety of aldehydes gave the corresponding vinyl arenecarbodithioates in moderate to good yields. Reaction of the vinyl dithiocarboxylate with nucleophiles such as potassium alkoxide or alkanethiolate was investigated and found to give the thioacylated products in high yields. Ab initio molecular orbital calculations of the model compound, vinyl dithioformate, are also discussed.
Spectrophotometric and Analogue Derivative Spectrophotometric Determination of Chromium(III) with 2-(5-Bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol
Authors: Shijo Yoshio , Sakai Kaoru
Published: July 2006

A sensitive method for the spectrophotometric determination of chromium(III) with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol (5-Br-PAPS) is described. 5-Br-PAPS reacts with chromium(III) to form a 1:2 (metal:ligand) complex in weakly acidic media upon heating at 95 °C. The complex has an absorption maxima at 592 nm and gives a constant absorbance in the pH range of 3.4–6.2. The molar absorptivity and sensitivity for an absorbance of 0.001 are 8.94×104 dm3 mol−1 cm−1 and 0.58 ng cm−2 respectively. The complex, once formed, is not decomposed by the addition of trans-1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid (CDTA). Thus, the selectivity of the method can be increased by the use of CDTA as a masking agent. The sensitivity of the method can be increased by employing analogue-derivative spectrophotometry, chromium(III) determination at parts-per-billion levels being feasible.
Nucleophilic Ring-Substitution Reactions of Unsymmetrical Quadridentate Schiff Base and Its Complex of Nickel(II) or Copper(II) with Ethyl Mercaptoacetate
Authors: Kasuga Kuninobu , Kuramitsu Hiroshi , Kadowaki Mayumi , Nagahara Takeo , Yamamoto Yasuo
Published: July 2006

The nucleophilic replacement of halogen on the methine carbon of a Schiff base complex of nickel(II) or copper(II) by ethyl mercaptoacetate in dichloromethane proceeds via a four-centered intermediate, in which two polarizable atoms, such as bromine and sulfur, may stabilize strained bond angles. In the case of a free Schiff base ligand, a relatively stable adduct was spectrophotometrically confirmed. The adduct is thought to have a configuration analogous to that of a spiro compound containing a five-membered ring. Free ligands show no absorption bands in the wavelength region longer than 340 nm, while the adduct shows band at 375 nm assignable to a n-π* transition.
13C NMR Study of the Cobalt(III) Complexes Containing Ethylenediamine-N-acetate (edma): [Co(edma)2]+ and [Co(ida)(edma)]
Authors: Ama Tomoharu , Kawaguchi Hiroshi , Yasui Takaji
Published: July 2006

The 13C NMR chemical shifts of the glycinate ring (G-ring) carbons of edma’s in the six geometrical isomers of [Co(edma)2]+ were measured. It was shown that the trans ligands and chelation form (meridional or facial form) influence the 13C NMR chemical shifts of the G-ring carbons in the same way as the magnetic anisotropy generated on the cobalt(III) center does. The chemical shifts of the ethylenediamine ring (E-ring) carbons of coordinating edma’s were also influenced by the trans ligands and the chelation form, similarly to those of the G-ring carbons. Four geometrical isomers of [Co(ida)(edma)] were newly prepared and their structural assignments were made according to their 13C NMR behavior.
The Chromatographic Behavior of Alkali and Alkaline Earth Metal Cations on Crown Ether-Modified Silica Gels and Polymer Matrices
Authors: Iwachido Tadashi , Naito Hirohiko , Samukawa Fumihiko , Ishimaru Kenji , Tôei Kyoji
Published: July 2006

Alkali and alkaline earth metal cations were chromatographed over silica gels and polymer matrices which had been modified by the addition of benzo-15-crown-5, benzo-18-crown-6, and benzo-21-crown-7, using water as the mobile phase. The retention sequences of the cations agreed closely with the stability sequences of the corresponding crown-ether complexes. The best separation was attained on the silica gels modified by the use of benzo-18-crown-6. The retention times increased in this sequence: Li+<Na+<Rb+<Cs+<K+; Mg2+<Ca2+<Sr2+<Ba2+. The retention sequences on the benzo-15-crown-5 and benzo-21-crown-7 columns were Li+<Na+≈Cs+<Rb+<K+ and Li+≈Na+<K+<Rb+≈Cs+ respectively. The resin-based columns showed similar retention sequences, but were inferior in their separation ability to the silica-based ones. The retention times were affected by many factors, such as the cation concentration, the species of the counter anions, the kind and composition of the second solvents in the mixed mobile phase, and the column temperature.