Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 78 , Issue 8
Showing 1-26 articles out of 26 articles from the selected issue
Award Accounts
The Chemical Society of Japan Award for Creative Work for 2003
  • Tamotsu Inabe
    2005 Volume 78 Issue 8 Pages 1373-1383
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    In this account, two representative approaches toward the control of molecular arrangements in molecular crystals are introduced, especially for π-radicals. One is “π–π stacking structure modification of macrocyclic π-ligand complexes”, in which the interaction is modified by simply introducing axial ligands. By this method, a number of conductors with various π–π stacking structures have been obtained. The other is “design of functional crystals utilizing hydrogen bonds”, in which anions with strong self-assembling ability are used for the formation of anion networks. If the interaction between the anions is stronger than that between π-radical cations, the cations are expected to be packed in the space provided by the networks with peculiar assembly formations that differ from those inherently preferable for the cations. The arrangement of π-radicals is directly related to the electronic functionalities of the crystal, and its control is crucial for the design of the specific electronic functionalities.
Accounts
  • Noboru Koga, Satoru Karasawa
    2005 Volume 78 Issue 8 Pages 1384-1400
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    Our approaches to the molecule-based magnets by using heterospin systems are reviewed. In our heterospin systems consisting of the organic 2p spins and the metal ion 3d spins, various pyridines carrying the organic spins were used as binding ligands for 3d metal ions. Carbenes generated by photolysis of diazo groups and persistent N-tert-butylaminoxyl radicals were employed as the organic spin sources. First, various model complexes were prepared and their magnetic couplings between the organic spin and the metal ion through the pyridine ligand were revealed. Based on the results of magnetic studies on model complexes, ferri- and ferromagnetic complexes having linear chain structures were designed and successfully prepared. When our heterospin systems were used under solution conditions, new fields were opened. Assemblies formed in frozen solution had magnetic behaviors exhibiting slow magnetic relaxations. Especially, when the anisotropic metal ion, high-spin cobalt(II) ion, was used as the metal ion in our heterospin system, the complex formed in frozen solution functioned as a single-molecule magnet (SMM). Such formation of a monometallic SMM was the first example reported.
BCSJ Award Article
Articles
  • Minoru Kato, Hidetoshi Tsuchiya, Yoshihiro Taniguchi
    2005 Volume 78 Issue 8 Pages 1411-1416
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    The effects of pressure and temperature on the conformational equilibrium of diethyl disulfide in various organic solvents were studied by Raman spectroscopy. From the pressure and temperature dependences of the intensities of S–S and C–S stretching bands, the volume and enthalpy differences between the trans-gauche-gauche and gauche-gauche-gauche conformers in organic solvents were determined. The volume differences of −1.1 – −1.3 cm3/mol are close to the values reported previously for liquid alkanes, which are explained by the packing effect of liquid. The solvent effect on the enthalpy difference also shows that the repulsive intermolecular interaction is a crucial factor in the conformational equilibrium of diethyl disulfide in the solutions. Based on the present results, the conformational change of the disulfide bridge in protein is discussed from the viewpoint of solution chemistry.
  • P. Senthil Kumar, Parminder Singh, Punam Uppal, Prasad V. Bharatam
    2005 Volume 78 Issue 8 Pages 1417-1424
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    The electronic structure of sulfimides has been studied using the model system HN=SH2, 1, by performing ab initio calculations. There are two minima on the path of rotation across the S–N bond in 1. G2 calculations showed that the S–N rotational barrier in 1 is 8.50 kcal/mol. The inversion around S in 1 goes through a high-energy barrier of 26.85 kcal/mol at the same level. Substituent effects on the electronic structure were studied using Me, Cl, and F as substituents. Charge analysis using the NPA method has been performed to understand the electronic factors responsible for the observed trends in the S–N interactions. The NBO method was employed to quantitatively estimate the second-order interactions, which indicate that the S–N partial double-bond character in sulfimides is mainly attributable to negative hyperconjugative interactions, rather than pπ–pπ interactions.
  • Shohei Yamakita, Naonobu Katada, Miki Niwa
    2005 Volume 78 Issue 8 Pages 1425-1430
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    The chemical vapor deposition of a silica overlayer in the presence of template molecules was examined on tin oxide in order to construct surface cavities with a molecular sieving property. On a SiO2/SnO2 sample prepared using a benzaldehyde template, 4-chlorobenzaldehyde and 4-methylbenzaldehyde were adsorbed, while 2-chlorobenzaldehyde and 2-methylbenzaldehyde were not adsorbed. The adsorption of 3-chlorobenzaldehyde was controlled by the thickness of the layer, i.e., the depth of the cavity. It was adsorbed by a shallow cavity, but not by a deep cavity. Thus the shape selectivity due to the shapes of the adsorbate molecule and the cavity was obtained.
  • Masahiro Kinoshita, Yuichi Harano
    2005 Volume 78 Issue 8 Pages 1431-1441
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    We analyze the interaction, the potential of mean force (PMF), between solute atoms in pure water and in solutions of various salts (NaCl, KCl, KBr, and KI) using the dielectrically consistent reference interaction site model theory. As for the PMF between solute atoms with like charges, the addition of increasing concentration of salt gradually leads from repulsive to attractive interactions. When the salt concentration becomes sufficiently high, the contact of like-charged atoms is stabilized and the stability is enhanced as the magnitude of the charge increases. For positive charges, the ability of salt to change the PMF is governed by anion species and becomes higher as the anionic size increases, while for negative charges it is governed by cation species and becomes higher as the cationic size decreases. Concerning the PMF between solute atoms with unlike charges, the addition of increasing concentration of salt gradually leads from attractive to repulsive interactions. The contact of unlike-charged atoms is less stabilized than in pure water. Physical insights into these results, which are generally applicable to solvation behavior of solute molecules, are then provided and the relevance to the salt-induced conformational transition of biomolecules is discussed in detail.
  • Yoshimasa Bando, Takahiro Matsuzawa, Norihiro Takashita, Tadashi Kawam ...
    2005 Volume 78 Issue 8 Pages 1442-1449
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    Two new organic electron donor molecules are synthesized on the basis of the ethylthio-substituted tetrathiapentalenes with a methylenedithio or a 1,3-dithiane unit. These donors provide four isostructural radical-cation salts, which belong to a new crystal type with uniform stacks of the donor molecules. These salts show metallic conductivity down to low temperatures, linear temperature dependence of the thermoelectric power, and asymmetrical ESR lineshapes. The obtained uniform structure is compared with the previous uniform structure from the viewpoint of crystal packing.
  • Lin Huang, Mahbod Bassir, Echchahed Bousselham, Serge Kaliaguine
    2005 Volume 78 Issue 8 Pages 1450-1456
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    The physical properties and redox chemistry of perovskite-type LaCoO3 prepared by reactive grinding and by the citrate method, have been comparatively studied by temperature-programmed reduction (TPR), X-ray diffraction (XRD), N2 adsorption–desorption, and infrared spectroscopy (IR). XRD and N2 adsorption–desorption measurements show that LaCoO3 prepared by reactive grinding possesses a smaller particle size and thus a greater specific surface area. An IR study suggests that there would exist a large amount of oxygen defects in LaCoO3 prepared by reactive grinding. TPR results illustrate that the reduction of LaCoO3 to Co0/La2O3 requires a higher temperature for a sample prepared by reactive grinding than for the one prepared by the citrate method. Due to a more difficult reduction, LaCoO3 prepared by reactive grinding displays a better stability of the perovskite structure than LaCoO3 prepared by the citrate method under a reducing atmosphere.
  • Julius Mbuna, Toshio Takayanagi, Mitsuko Oshima, Shoji Motomizu
    2005 Volume 78 Issue 8 Pages 1457-1462
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    Weak ion-association equilibrium was analyzed in a water-acetonitrile solution at 25 °C by capillary zone electrophoresis using an ordinary silica capillary. The ion associates examined were formed between some inorganic anions and symmetrical tetraalkylammonium ions, where a series of acetonitrile compositions up to 62.2% (m/m) were investigated. Ion-association constants, Kass, were determined by analyzing the changes in the electrophoretic mobility; the Kass values for most of the anions increased up to about 47% (m/m) acetonitrile, beyond which they remained constant, or decreased slightly. The ion-association equilibrium between tetramethylammonium and bromide ions in aqueous-acetonitrile and in aqueous-ethanol media were compared through the Gibbs free energy of transfer, which revealed that the extent of the equilibrium in aqueous-acetonitrile media is dependent mainly on the increasing instability of Br. On the other hand, those in aqueous-ethanol media depend on the instabilities of both tetramethylammonium and bromide ions.
  • Sadayuki Himeno, Masayo Takamoto, Tadaharu Ueda
    2005 Volume 78 Issue 8 Pages 1463-1468
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    The formation process of the α- and β-Keggin-type [PW12O40]3− complexes was investigated in an aqueous 50 mM (M = mol dm−3) W(VI)–5.0 mM P(V) system. The 31P NMR study confirmed the formation of A-α-[PW9O34]9−, A-β-[PW9O34]9−, α-[PW11O39]7−, and β1-[PW11O39]7− on acidification of an alkaline solution of WO42− and HPO42− to pH 7.5 or below. An isomeric mixture of α- and β-[PW12O40]3− was obtained on further acidification of such solutions containing both α- and β-type lacunary complexes to pH 1 or below. On the other hand, heating of the W(VI)–P(V) system caused A-α-[PW9O34]9−, A-β-[PW9O34]9−, and β1-[PW11O39]7− to disappear completely, leaving α-[PW11O39]7−. Acidification of the α-[PW11O39]7− solution produced only α-[PW12O40]3−.
  • Yasushi Nishihara, Chikako Yoda, Masumi Itazaki, Kohtaro Osakada
    2005 Volume 78 Issue 8 Pages 1469-1480
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    [IrH(CO)(PPh3)3] promotes ring opening of 2-phenyl-1-methylenecyclopropane at room temperature to produce the Ir complex with a chelating 2-phenyl-3-butenyl ligand, [Ir{η2-CH2CH(Ph)CH=CH2C1}(CO)(PPh3)2] (1). The reaction of excess 2-phenyl-1-methylenecyclopropane with [IrH(CO)(PPh3)3] at 50 °C yields [Ir{η2-(o-C6H4)CH(Me)CH=CH2C1}(CO)(PPh3)2] (2), accompanied by the formation of 1-phenyl-1,3-butadiene and 2-phenyl-1,3-butadiene. 2,2-Diphenyl-1-methylenecyclopropane reacts with [IrH(CO)(PPh3)3] to afford [Ir{η2-CH2CPh2CH=CH2C1}(CO)(PPh3)2] (3) at 50 °C and [Ir{η2-(o-C6H4)CMe(Ph)CH=CH2C1}(CO)(PPh3)2] (4) at 100 °C. Heating a solution of 3 at 100 °C also forms 4 quantitatively. X-ray crystallography of 3 reveals a penta-coordinated structure around the Ir center bonded to a chelating 2,2-diphenyl-3-butenyl ligand. The reactions of 2,2-diphenyl-1-methylenecyclopropane and of 2,2-di(4-fluorophenyl)-1-methylenecyclopropane with [RhH(CO)(PPh3)3] at room temperature yield [Rh{η2-CH2CAr2CH=CH2C1}(CO)(PPh3)2] (5a: Ar = Ph, 5b: Ar = C6H4-F-4). The reactions at 50 °C cause ring opening of the substrate and orthometalation of the phenyl group to afford [Rh{η2-(o-C6H4)CMe(Ph)CH=CH2C1}(CO)(PPh3)2] (6a) and [Rh{η2-(o-C6H3-F-4)CMe(C6H4-F-4)CH=CH2C1}(CO)(PPh3)2] (6b), respectively. Formation of 1,1-diaryl-1,3-butadiene is observed during the reaction. Heating a solution of 5a at 50 °C produces 1,1-diphenyl-1,3-butadiene and an allylrhodium complex, 8, rather than 6a, although the reaction of excess 2,2-diphenyl-1-methylenecyclopropane with 5a at 50 °C affords 6a in 60%. The mechanisms of the above reactions are discussed based on the products and reaction rates. Coordination of P(OMe)3 to the Rh center of 5a causes insertion of the CO ligand into the Rh–C bond to afford [Rh{η2-CO-CH2CPh2CH=CH2C1}(P(OMe)3)3] (7).
  • Rameshwar Dass, Anil Kumar Bishnoi, Ram Gopal Sharma
    2005 Volume 78 Issue 8 Pages 1481-1483
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    Molybdenum(V), obtained from Mo(VI) by reduction in presence of ascorbic acid in sulfuric acid medium, has been determined spectrophotometrically. Mo(V) formed an intense yellow 1 : 2 complex with 6-chloro-3-hydroxy-2-(5-methyl-2-furyl)-4H-chromen-4-one (CHMFC); the complex is extractable into 1,2-dichloroethane having λmax at 437 nm. The proposed method is free from interference of many analytically important elements, with a molar absorptivity and Sandell’s sensitivity of 5.32 × 104 dm3 mol−1 cm−1 and 0.0018 μg Mo cm−2, respectively.
  • Tokimitsu Fukukai, Kazuya Yabe, Yoshihiro Ogawa, Naohide Matsumoto, Je ...
    2005 Volume 78 Issue 8 Pages 1484-1486
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    A spin crossover FeIII complex, [FeHim2L]BPh4·2MeOH, was synthesized and studied, where Him = imidazole, H2L = N2O2 Schiff base ligand of the 1 : 1 : 1 condensation product of acetylacetone, ethylenediamine, and o-hydroxyacetophenone, and BPh4 = tetraphenylborate. The complex consists of a cyclic dimeric structure, {···[FeHim2L]···(MeOH)···(MeOH)···}2, constructed by the hydrogen bonds. Magnetic measurements revealed that a rather steep spin transition from the LS to HS FeIII states occurs above 300 K, and the elimination of the methanol molecules changes the spin transition from steep to gradual due to destruction of the cyclic dimeric structure.
  • Sadayuki Matsuda
    2005 Volume 78 Issue 8 Pages 1487-1491
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    The conformation changes in S-100a.a′ and S-100b caused by K+-binding were determined by several methods in the apo-state and in the Ca2+-bound state. The reactivities of the cysteine (Cys) residues in S-100a.a′ and S-100b to a thiol-specific reagent, 2,2′-dinitro-5,5′-dithiodibenzoic acid (DTNB), were not affected by the K+-binding. On the contrary, the reactivities of those in Ca2+/S-100a.a′ and Ca2+/S-100b toward DTNB were enhanced or decreased, respectively, by the K+-binding. The conformation changes in S-100b, Ca2+/S-100a.a′, and Ca2+/S-100b caused by the K+-binding were also detected using a fluorescence environmental probe, 2-p-toluidinonaphthalene-6-sulfonate (TNS). A clear difference in the decrease of the TNS fluorescence intensity obtained by the K+-binding between S-100a.a′ and S-100b was demonstrated in the Ca2+-bound state. The measurements of the difference absorption spectrum of S-100a.a′ obtained by the K+-binding showed a positive spectrum, while those of S-100b showed a negative spectrum, regardless of the Ca2+-binding.
  • Yasuchika Yonezawa, Naoki Tani, Chung-gi Shin
    2005 Volume 78 Issue 8 Pages 1492-1499
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    The total synthesis of naturally occurring bistratamides G (1) and H (2) from various kinds of dehydrooligopeptides is described. First of all, the promising building blocks of 1 and 2: N-{2-[(S)-1-(N-benzyloxycarbonyl)amino-2-methylpropyl]oxazole (4)- and N-{2-[(S)-1-(N-t-butoxycarbonyl)amino-2-methylpropyl]thiazol-4-ylcarbonyl}-L-Val-(S)NH2 (5), and methyl (S)-2-{1-[N-(3-bromo-2-oxopropanoyl)amino-2-methylpropyl]}-5-methyloxazole-4-carboxylate (6), as the left- and right-half components of the linear precursor of 1 and 2, were synthesized. Subsequent thiazolation between 4 or 5 and 6, respectively, followed by deprotection of both N- and O-protecting groups of the two formed linear trisheterocyclic peptides. By final macrocyclization using BOP as condensing agent under high-dilution conditions these peptides gave the expected 1 and 2.
  • Juan Luis Delgado, Pilar de la Cruz, Vicente López-Arza, Fernan ...
    2005 Volume 78 Issue 8 Pages 1500-1507
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    The synthesis of three novel pyrazolo[60]fullerene derivatives containing electron-withdrawing substituents has been described. High solubility in ordinary organic solvents was proved. Their electrochemical properties of pyrazolo[60]fullerenes showed better electron affinity than pristine C60 in the ground state. The nanosecond transient absorption spectra showed clear evidence for photoinduced electron transfer from TTF to the excited triplet state of the pyrazolo[60]fullerenes, in which stronger electron-withdrawing substituents accelerate the rates of the photoinduced electron-transfer, indicating a high electron-acceptor ability of the excited triplet state of pyrazolo[60]fullerenes.
  • Yoshiaki Oohashi, Kentarou Fukumoto, Teruaki Mukaiyama
    2005 Volume 78 Issue 8 Pages 1508-1519
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    The esterification of carboxylic acids with alcohols by using di-2-thienyl carbonate (2-DTC) in the presence of a catalytic amount of 4-(dimethylamino)pyridine (DMAP) proceeded smoothly to afford the corresponding esters in good-to-high yields along with 2(5H)-thiophenone. This esterification was accelerated by the addition of an equimolar amount of iodine to afford the esters in higher yields within a shorter reaction time. Further, cyclization of ω-hydroxycarboxylic acids with an equimolar amount of 2-DTC in the presence of a catalytic amount of DMAP, followed by the addition of 1–4 equimolar amounts of iodine, afforded the corresponding lactones in good-to-high yields under mild conditions. This method was successfully employed in the synthesis of erythro-aleuritic acid lactone.
  • Atsushi Kawachi, Hirofumi Maeda, Kohei Tamao
    2005 Volume 78 Issue 8 Pages 1520-1527
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    Intramolecular reactions of the [(allyloxy)silyl]lithiums and the [(propargyloxy)silyl]lithiums have been investigated. The [(allyloxy)silyl]lithiums proceed in two reaction modes depending on the electronic effect of the substituents at the terminus of the olefin. The [(allyloxy)silyl]lithiums bearing hydrogen, n-C6H13, or trimethylsilyl substituent undergo the [2,3]-sila-Wittig rearrangement to afford the lithium allylsilanolates, while those bearing the phenyl, thienyl, or triphenylsilyl substituent experience the 4-exo-trig cyclization and subsequent 1,3-cycloelimination to give the lithium cyclopropylsilanolates. On the other hand, the [(propargyloxy)silyl]lithiums preferentially undergo the 4-exo-dig cyclization over the [2,3]-sila-Wittig rearrangement in all cases.
  • Takanori Matsuda, Masaomi Makino, Masahiro Murakami
    2005 Volume 78 Issue 8 Pages 1528-1533
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    An addition/ring-opening reaction of aryl- and alkenylboronic acids to cyclobutanones took place in 1,4-dioxane at 100 °C in the presence of a rhodium(I) catalyst bearing tri-t-butylphosphine, affording ring-opened ketones. Mechanistically, the reaction proceeded through the addition of an organorhodium species to the carbonyl group of a cyclobutanone and a subsequent ring-opening of the resulting rhodium cyclobutanolate through β-carbon elimination. A deuterium-labeling experiment revealed that an alkylrhodium species generated by the β-carbon elimination underwent successive β-hydride elimination/re-addition processes to form the η3-oxaallylrhodium intermediate, which was readily protonated to afford the product.
  • Kaname Tsuchii, Mikio Doi, Ikuko Ogawa, Yoshiyuki Einaga, Akiya Ogawa
    2005 Volume 78 Issue 8 Pages 1534-1548
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    This paper describes full details of a series of intermolecular domino reactions mediated by diphenyl diselenide (PhSeSePh). Diphenyl diselenide, which has just the right strength of carbon radical capturing ability, can be employed as a useful mediator for intermolecular domino reactions of unsaturated compounds. Upon irradiation through Pyrex with a tungsten lamp (hv > 300 nm), a sequential addition of diphenyl diselenide to alkynes bearing an electron-withdrawing group and alkenes bearing an electron-donating group proceeds successfully to provide the corresponding intermolecular three-component coupling products in high yields. In place of alkenes, the use of isocyanides leads to the formation of the corresponding three-component coupling products of alkynes, isocyanides, and (PhSe)2, selectively. Moreover, when two kinds of alkenes (i.e., electron-rich alkenes and electron-poor alkenes) are used in this photoinduced alkyne-(PhSe)2 reaction system, a novel domino reaction of diphenyl diselenide with an alkyne and two kinds of alkenes, followed by 5-exo radical cyclization, takes place sequentially to provide the corresponding cyclic four-component coupling products in good yields.
  • Tadaaki Ohgiya, Kensuke Nakamura, Shigeru Nishiyama
    2005 Volume 78 Issue 8 Pages 1549-1554
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    Total synthesis of (+)-tanikolide, a bioactive δ-lactone of marine origin, was successfully accomplished by utilizing a bromoalkene derivative conveniently synthesized from the corresponding 1-acyloxy-2,3-dibromoalkane by the regioselective and mild HBr-elimination reaction, along with the Pd-mediated C–C coupling reaction and the Sharpless asymmetric epoxidation as key steps.
  • Toshihiko Ogura, Ryuichiro Kamimura, Akinobu Shiga, Takahiro Hosokawa
    2005 Volume 78 Issue 8 Pages 1555-1557
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    The trend of aldehyde selectivity observed in the oxidation of 1-decene with PdCl2(CH3CN)2/CuCl2 in alcohol (ROH) under O2 can be evaluated by the overlap populations for Pd–C and C–OR bonds in the oxypalladation step with paired interacting orbitals (PIO) analysis. The use of t-BuOH affords decanal in 84% regioselectivity.
  • Eui-Chul Kang, Shingo Kataoka, Kenji Kato
    2005 Volume 78 Issue 8 Pages 1558-1564
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    Alkyl phosphorylcholine amphiphiles bearing one linear chain and one asymmetrically branched alkyl chain were successfully synthesized using 2-chloro-2-oxo-1,3,2-dioxaphospholane in tetrahydrofuran or ethyl acetate. 1H and 31P NMR studies revealed that the linear alkyl phosphorylcholines (Cn-PC) provide aqueous micelles in D2O and reverse micelles in CDCl3, while the branched alkyl phosphorylcholines (ISOFOLn-PC) give vesicles in D2O. The critical micelle concentrations (CMCs) of Cn-PC were measured by fluorescence dye solubilization methods: the CMCs of C12-PC, C14-PC, C16-PC, and C18-PC were 1.6, 0.38, 0.16, and 0.11 mM, respectively, in water at 25 °C. The critical association concentrations (CACs) of ISOFOL16-PC, ISOFOL20-PC, and ISOFOL24-PC were 0.068, 0.005, and 0.077 mM, respectively, in water at 25 °C. The vesicle size of ISOFOLn-PC in aqueous solution was measured by the dynamic light scattering method. The mean diameter of ISOFOLn-PC vesicles was approximately 30 nm and the size distribution was relatively monodisperse. The ISOFOLn-PC vesicles formed were colloidally stable in water over the period of several weeks.
  • Tsukasa Tamai, Koji Inazu, Ken-ichi Aika
    2005 Volume 78 Issue 8 Pages 1565-1574
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    Dichlorodifluoromethane (CCl2F2, 1% in He) decomposition with simultaneous halogen fixation by vanadium oxide supported on magnesium oxide was studied at 723 K in a flow apparatus. The pretreatment condition and vanadium loading of supported vanadium oxide samples affected the CCl2F2 decomposition efficiency. Through characterization studies (XRD, IR, Raman, and XPS) and reference experiments, Mg3(VO4)2 was revealed to be the active species to initiate CCl2F2 decomposition, leading to MgF2, MgCl2, and CO2 formation. The model experiments also suggested a detailed mechanism that VOCl3 was formed from Mg3(VO4)2 by a reaction with CCl2F2 or the major intermediate compound CCl4, and that VOCl3 reacted with MgO to regenerate Mg3(VO4)2 and to promote chlorine fixation as MgCl2.
  • Li Mingqiang, Jian Xigao
    2005 Volume 78 Issue 8 Pages 1575-1579
    Published: 2005
    Released: August 04, 2005
    JOURNALS RESTRICTED ACCESS
    A new reaction-controlled phase-transfer catalyst system has been designed and synthesized. In this system, heteropoly blue, [C7H7N(CH3)3]3PMo4O16, is used for the catalytic epoxidation of olefins with H2O2 as the oxidant. In this system, the catalyst not only can be recovered, like heterogeneous catalyst, but also acts as a homogeneous catalyst. The main products are epoxide of olefins and H2O; no co-product forms. The system exhibits high conversion and selectivity as well as excellent catalyst stability. 31P NMR spectra, UV–vis spectra, and infrared spectra are used to analyze the reason for the phase transfer of the catalyst, indicating that the change of structure leads to the formation of reaction-controlled phase-transfer catalyst.
feedback
Top