Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 66 , Issue 8
Showing 1-50 articles out of 61 articles from the selected issue
  • Yoshifumi Koide, Tetsushi Oka, Akemi Imamura, Hideto Shosenji, Kimiho ...
    1993 Volume 66 Issue 8 Pages 2137-2142
    Published: 1993
    Released: August 09, 2006
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    The resorcinol-type calix[4]arenes with alkyl side chains, [4]Ar-Rn, were prepared and then investigated as flotation collectors of Cs+. Alkali metal ions (Na+, K+, Rb+, and Cs+) were extracted in the pH range of 9.5—12.5 with [4]Ar-Rn. Moreover, the surface-active [4]Ar-Rn had competence to float Cs+ as a complex in a foam film (adsorbates) when short-chain [4]Ar-Rn (n = 4—8) were used for foam fractionation, and as scum when long-chain [4]Ar-Rn (n = 8—16) were used for ion flotation. The Cs+ was floated selectively with [4]Ar-Rn from a mixture of Na+, K+, Rb+, and Cs+, due to the strong binding to Cs+.
  • Yasuki Nakashima, Moritaka Fukunaga, Keiko Suzuki, Kensuke Takahashi
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2143-2148
    Published: 1993
    Released: August 09, 2006
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    One- and two-bond deuterium isotope effects (1Δ and 2Δ) on 13C chemical shifts for methylpyridines and their N-oxides were investigated. The 1Δ values for methylpyridines agree with the calculated values, which are based on a simple additive rule of the methyl substituent effects. On the other hand, the additive rule was not satisfied in 1Δ for their N-oxides. This is attributed to a steric interaction between the substituent and the N-oxide group.
  • Maw-Ling Wang, Shahng-Wern Chang
    1993 Volume 66 Issue 8 Pages 2149-2155
    Published: 1993
    Released: August 09, 2006
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    By employing phase transfer catalysis, formaldehyde acetals were synthesized from the reaction of alcohols and dibromomethane at moderate temperatures. Using a high alkaline concentration, the reaction could be improved to obtain a 100% yield by reacting dibromomethane and 1-alcohol employing tetrabutylammonium bromide (TBAB) as a phase transfer catalyst. Six kinds of alcohols with various structures, four sorts of solvents with various dielectric constants and seven types of catalysts were examined to test their reactivities to the reactions. Only one unique product with two alkoxides substituents was observed which indicated the presence of a rather fast reaction rate during the second reaction of the organic phase. The reaction was dramatically enhanced by adding a small amount of quaternary ammonium salt (QX) to obtain a 100% yield utilizing the alcohols with nonbonding electron pairs within a short period of reaction time. The conversion was also observed to be strongly dependent upon the structure of the quaternary ammonium salts. The reaction rate and the product yield were satisfactorily accounted for the chemical reaction equilibrium of alcohols and KOH in the aqueous phase, the hydration of the active catalyst (QOR) in the organic phase and the distribution of QOR between two phases.
  • Hatsumi Mori, Izumi Hirabayashi, Shoji Tanaka, Yusei Maruyama
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2156-2159
    Published: 1993
    Released: August 09, 2006
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    The crystal and electronic structures and electrical resistivity of new chlorine complex, (BEDT-TTF)3Cl2.5(H5O2), were investigated. The two-dimensional donor sheet and the anion layer stack alternately along the b-axis. The packing pattern of donors is similar to that of (BEDT-TTF)3(ClO4)2 and the sharp metal-insulator transition was observed at 170 K. It is interesting that not only donor and anion but also the third component cation, H+, determines the 3/4-filled band structure.
  • Hamdan Suhaimi, Laili Che Rose, Anuar Kassim
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2160-2165
    Published: 1993
    Released: August 09, 2006
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    A phase studies was carried out on the phase equilibria in the three component systems of single and binary mixture (1 : 1) of trimethyltetradecylammonium bromide (TTAB) and hexadecyltrimethylammonium bromide (HTAB) with water and 1-hexanol at 30 °C. The phases were separated by repeated centrifugation. The birefringence was observed under cross polarizers and their consistency, texture and optical pattern were examined under the polarizing microscope. On the basis of the results obtained, a phase diagram was drawn that consists of two phases of isotropic solution and two mesophases. Results also showed a larger region for the lamellar liquid crystalline in the mixed system. The critical micelle concentration for the micellar region of the mixture was found at 0.0014 mol dm−3.
  • Yoshihiro Kubozono, Akiko Hirano, Shinichi Nagasawa, Hironobu Maeda, S ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2166-2173
    Published: 1993
    Released: August 09, 2006
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    Crystals of sodium hydrogen L-tartrate monohydrate (NaHC4H4O6·H2O) were grown from the aqueous solution, while potassium hydrogen L-tartrate (KHC4H4O6) crystallized as anhydrate. Their crystal structures were determined by X-ray diffraction method. The hydrogen bonds between the carboxyl and carboxylate groups in these crystals are rather long; O···O 2.533(3) and 2.531(1) Å for the sodium and potassium compounds, respectively. The sodium and potassium ions are coordinated by eight O atoms at the corners of distorted square antiprism, Na+···O 2.404(2)—2.826(3) Å and K+···O 2.718(1)—3.059(1) Å. The crystal and molecular structures have been compared with those of the corresponding rubidium, caesium, and ammonium salts, and discussed with the aid of semiempirical and ab initio MO methods.
  • Toshiaki Mabuchi, Tsuneo Fujii
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2174-2181
    Published: 1993
    Released: August 09, 2006
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    The fluorescence and fluorescence-excitation spectra of doped benzo[f]quinoline (BQ) during the sol–gel–xerogel transitions of two reaction systems of mixed alkoxides that were catalyzed by HCl and NaOH (or NH3) have been observed as a function of time. The mixed alkoxides were comprised of tetraethyl orthosilicate (TEOS) and diisobutoxyaluminum triethyl silicate (SAE) (Si : Al = 10 : 0 and 9 : 1). During the reaction, it was found that BQ forms three different fluorescent species, neutral, protonated, and an ion pair. The neutral form was seen in the first stage of the reaction and emitted a structured fluorescence. The protonated form appeared in the next reaction stage and it gave a broad and structureless band with a peak around 440 nm. The ion-pair form, produced from BQ and an –OH group of –O–Si–O– and/or –O–Si–O–Al–O– networks, appeared in the last stage of the reaction and its fluorescence peak was located at around 400 nm. The ion pair could not be detected in solutions, but it was found in the xerogel state. The appearance and disappearance of the three species of BQ reflect the condition of microenvironment around the doped BQ during the sol–gel reaction of the TEOS and TEOS+SAE systems. Therefore, the measurements of the fluorescence spectra of BQ are useful for the photophysical investigation on the sol–gel–xerogel transitions of systems containing metal alkoxides such as TEOS and TEOS+SAE.
  • Guiqing Xu, Kenji Okuyama, Masatsugu Shimomura
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2182-2186
    Published: 1993
    Released: August 09, 2006
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    An azobenzene-containing odd-number amphiphile, C3AzoC5N+Br, was crystallized by the vapor-diffusion method. The crystal is monoclinic with the space group P21, a = 25.866(3), b = 7.3560(9), c = 6.4833(7) Å, β = 96.255(9)°, and Z = 2. The structure was solved by the direct method and refined by the full-matrix least-squares method: R = 0.03 for 2116 observed reflections (2θ < 130°, Cu , λ = 1.5418 Å). The molecules are arranged in an antiparallel fashion and interdigitated mutually. The azobenzene chromophores are aligned at the center part of the hydrophobic layer (the H-aggregation state) and inclined about 65° to each other. In the hydrophilic layer, detailed structures are different from those of even-number compounds with the H-aggregation state, resulting in an odd-even effect on their transition temperature.
  • Björg Nygaard Cyvin, Jon Brunvoll, Sven Josef Cyvin
    1993 Volume 66 Issue 8 Pages 2187-2189
    Published: 1993
    Released: August 09, 2006
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    The pentacyclic structures are considered within the initiated studies of polycyclic conjugated hydrocarbons. A complete mathematical solution (in terms of generating functions) is presented for the numbers of CnHs isomers of these structures. Some details of the analysis are given for the doubly-branched catafused structures of the category in question, a subclass to which C16H8 cyclic bicalicene and C24H16 tetraphenylene belong.
  • Tetsuyuki Iwamoto, Setsuo Kashino
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2190-2195
    Published: 1993
    Released: August 09, 2006
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    The crystal structure at an intermediate stage in the solid-state photodimerization of α-(acetylamino)cinnamic acid dihydrate has been analyzed at the conversion rate of 12%: C11H11NO3·2H2O, Mr = 241.24, monoclinic, P21/a, a = 18.346(5), b = 6.072(2), c = 11.310(4) Å, β = 105.90(2)°, V = 1211.8(6) Å3, Z = 4, Dx = 1.323 Mg m−3, Cu (λ = 1.5418 Å), μ = 0.89 mm−1, F(000) = 512, T = 295 K, R = 0.108 for 1678 unique reflections with |Fo| larger than σ(Fo). The present study revealed the structures of the monomer and photodimer components at the intermediate stage. The results made possible the discussion on the role of intermolecular hydrogen bonds and on the feature of the atomic movements accompanied by the reaction.
  • Toshiyuki Uehara, Hirofumi Okabayashi, Keijiro Taga, Tadayoshi Yoshida ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2196-2203
    Published: 1993
    Released: August 09, 2006
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    N-Octanoyl-L-glutamic acid oligomers (residue number, N = 2—6) have been synthesized in order to study their molecular conformations in the solid state. The X-ray powder diffraction patterns and vibrational spectra of these oligomers have been investigated and compared with those of the α-helical and β-sheet conformations of poly-L-glutamic acid. For fresh samples of these oligomers, the tetramer, pentamer, and hexamer take up a conformation similar to the β1-form of poly-L-glutamic acid. However, the β1-type conformation of these oligomers is rapidly transformed to a β2-type conformation with time at room temperature, indicating that a transition similar to the β1β2 transition of poly-L-glutamic acid occurs, even in the tetramer, pentamer, and hexamer. For fresh samples of the dimer and trimer, these molecules take up the β2-type structure. This means that the critical size of the oligomer for the formation of the β1β2-type transition is the tetramer.
  • Toshiyuki Uehara, Hirofumi Okabayashi, Keijiro Taga, Tadayoshi Yoshida ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2204-2209
    Published: 1993
    Released: August 09, 2006
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    Barium salts of N-octanoyl-L-glutamic acid oligomers (oct-oligomer salts, residue number, N = 2—6, 8, 10, 12, 14, 16, 18, 20, and 22) have been prepared. The vibrational spectra of these molecules were measured and compared with those of β-Ca-poly(L-glutamic acid). For the vibrational spectra of these oligomer salts, the very broad amide I bands at 1644—1655 cm−1 (IR), amide III bands at 1240—1256 cm−1 (Raman) and at 1240—1250 cm−1 (IR) are due to a disordered structure. The Raman bands at 840—855 cm−1 and their counter part at 835—848 cm−1 in the IR spectra may also come from disordered structures. In the CαC stretching-mode region, which strongly reflects the skeletal backbone structure, the Raman bands at 941—944 cm−1 were observed in common for those oligomer salts having residue numbers of N = 4—22, and correspond well to the 943 cm−1 band characteristic of the extended helical conformation of charged poly(L-glutamic acid). We may conclude that the oligomer salts (N = 2—22) have disordered structures. However, the oligomer chains having at least residue numbers above N = 4 are locally relatively regular and may take up an extended helical structure.
  • Toshiyuki Uehara, Hirofumi Okabayashi, Keijiro Taga, Tadayoshi Yoshida ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2210-2218
    Published: 1993
    Released: August 09, 2006
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    Trimers and tetramers of N-acyl-L-glutamic acid oligomers (Glu-oligomers) with various acyl chains have been prepared. For these Glu-oligomer molecules the vibrational spectra were measured and compared with those of two β-forms (β1 and β2) and the α-helical form of poly(L-glutamic acid). For these samples the molecules take up a β2-type structure in the solid state. The long acyl chain in the oligomers induces stronger hydrogen bonds between the side-chain COOH and the amide linkages; this effect is due to the close packing of the long acyl chains accompanying the reduction of the intersheet spacing. Moreover, the long acyl-chain effect strongly depends upon the residue number of the oligomer. For cast films of Glu-oligomers made onto an NaCl plate, these oligomer molecules assume an α-helical type structure. For the α-helical type oligomers, it is also found that the long acyl chain induces stronger hydrogen bonds in the side-chain COOH groups, and that the effect depends on the residue number.
  • Satoshi Takahashi, Masanobu Seki, Katsumi Setoyama
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2219-2224
    Published: 1993
    Released: August 09, 2006
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    In an SrSO4–H2O system the formation of a new compound of SrSO4·1/2H2O has been found by coprecipitation from solutions of Sr2+ and SO42−. This was found to have a similar crystal structure to CaSO4·1/2H2O of a hexagonal crystal system. The lattice constants thereof were calculated. It was also found that SrSO4·1/2H2O is not stable in water, but changes to a stable well-known orthorhombic anhydrous strontium sulfate. For a CaSO4–SrSO4–H2O system, a series of solid solutions of CaSO4·1/2H2O and SrSO4·1/2H2O was prepared, which had similar X-ray diffraction patterns to SrSO4·1/2H2O. These solid solutions were unstable in water, and converted with time to a mixture of stable anhydrous SrSO4 and CaSO4·2H2O.
  • Yuriko Kaida, Yoshio Okamoto
    1993 Volume 66 Issue 8 Pages 2225-2232
    Published: 1993
    Released: August 09, 2006
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    The optical resolving ability of two types of regioselectively carbamoylated cellulose and amylose with 3,5-dimethylphenyl and 3,5-dichlorophenyl isocyanates was evaluated. One had 3,5-dimethylphenylcarbamate groups at the 2 and 3 positions and a 3,5-dichlorophenylcarbamate group at the 6 position; the other had 3,5-dichlorophenylcarbamate groups at the 2 and 3 positions and a 3,5-dimethylphenylcarbamate group at the 6 position. In cellulose derivatives, the side chains at the 2,3, and 6 positions seem to interact complicatedly with racemates. On the other hand, in the amylose derivatives, the side chains at the 2 and 3 positions may mainly influence the chiral recognition ability. The optical resolving abilities of the cellulose and amylose derivatives having irregularly either 3,5-dimethylphenyl- or 3,5-dichlorophenylcarbamate groups at the 2,3, and 6 positions were also examined.
  • Ruma Chakraborty, Shuvendu S. Bhattacharyya, Arabinda K. Das
    1993 Volume 66 Issue 8 Pages 2233-2236
    Published: 1993
    Released: August 09, 2006
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    The electrothermal atomic absorption spectrometry has been used to develop a routine and interference-free method for the determination of lead in fish tissues. Bismuth(III) nitrate was used as a chemical modifier. The analytical curves of lead were studied by using pyrolytically coated graphite tubes. The instrumental conditions, electrothermal atomizer programme, concentration of the modifier, the calibration and addition curves were studied. A comparative study was also made between Pd(NO3)2 and Bi(NO3)3 as chemical modifiers. Not only a better limit of detection value has been obtained in comparison to Pd(NO3)2 modifier but also a lower atomization temperature, hence an extension of the life period of the graphite tube compared to magnesium nitrate+ammonium dihydrogen phosphate mixed modifier could be achieved in the present method.
  • Tadashi Segawa, Tamio Kamidate, Hiroto Watanabe
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2237-2241
    Published: 1993
    Released: August 09, 2006
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    The horseradish peroxidase (HRP)-catalyzed chemiluminescence (CL) reaction of fluorescein (FL) with hydrogen peroxide (H2O2) was carried out in aqueous media buffered by citrate, phosphate, imidazole, and 3-morpholino-1-propanesulfonic acid (MOPS) at pH 7.0. When the H2O2 concentration was below 2 × 10−5 M, one peak was observed in a CL response curve in each buffer component tested. In contrast, only MOPS gave two peaks in the response curve at a concentration higher than 2 × 10−5 M H2O2. The CL emission of the second peak was attributable to formation from an excited FL dianion. The total photon amounts of CL emission of the second peak were dependent on the MOPS concentration. Dissolved oxygen was consumed during the occurence of the second peak. These results could be explained by taking into account the role of MOPS as an energy transferor. That is, MOPS reacted successively with the FL radical, produced from the catalytic cycle of HRP, and the dissolved oxygen to form an excited MOPS compound. An energy transfer occurred from the excited MOPS compound to the FL dianion, resulting in the emission of light.
  • Junji Noro, Tatsuya Sekine
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2242-2250
    Published: 1993
    Released: August 09, 2006
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    The solvent extraction of europium(III) in 0.1 mol dm−3 sodium nitrate solutions with 1-naphthoic acid (HA) into chloroform was studied in the absence and presence of tetrabutylammonium ions (tba+) or trioctylphosphine oxide (TOPO). In the absence of tba+ and TOPO the distribution ratio of europium(III) with 0.1 mol dm−3 1-naphthoic acid was higher when the initial concentration of the metal was higher under otherwise identical conditions. This could be explained in terms of the extraction of a polynuclear species, Eu2A6(HA)2, in addition to a mononuclear species, EuA3HA. Furthermore, by the addition of tba+ or TOPO, the extraction of europium(III) was greatly enhanced. This could be explained in terms of the extraction of the ternary complex, EuA4tba+, or the adducts, EuA3TOPO and EuA3(TOPO)2, like that found in the extraction of this metal ion with β-diketones. In these systems the extracted anionic complex with tba+ or the adducts with TOPO were only mononuclear, even under conditions in which the polynuclear species were extracted in the absence of these.
  • Rameshwar Dass, Jaswant Ram Mehta
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2251-2254
    Published: 1993
    Released: August 09, 2006
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    2-(2-Furyl)-3-hydroxy-4H-chromen-4-one (FHC) has been used as an analytical reagent for the spectrophotometric determination of molybdenum. Molybdenum(VI) in the presence of several cations except Sb(V), Bi(III), and Ce(IV), anions and complexing agents except oxalate forms a yellow 1 : 2 complex with FHC. The complex was extractable into chloroform from 0.01—0.25 mol dm−3 acetic acid (pH 4.2—2.9) and was stable for 2 h. The complex showed an absorption maximum at 414 nm with a molar absorptivity of 4.99 × 104 dm3 mol−1 cm−1 and Sandell’s sensitivity equal to 0.0019 μg Mo cm−2. Beer’s law was obeyed over the concentration range of 0—2.9 ppm. The equilibrium constant was found to be 6.70 × 10−12. For 1 μg Mo cm−3 the standard deviation was 0.004 with a relative mean error of ±0.7%. The method is simple, selective, precise and rapid and has been applied to the determination of molybdenum in synthetic and standard samples.
  • Mineo Sato, Tetsuro Jin, Yoshiki Hama, Kazuyoshi Uematsu
    1993 Volume 66 Issue 8 Pages 2255-2259
    Published: 1993
    Released: August 09, 2006
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    The chemical lithium intercalation of defect perovskite LiCuM3O9 (M = Ta, Nb) compounds has been performed by using butyllithium. The content of the inserted lithium ions in the compounds was found to be ca. 1 mol per unit formula for M = Ta and ca. 4 mol per unit formula for M = Nb. The crystal structure of the intercalated compound was determined based on the powder X-ray diffraction pattern. The intercalated product was well crystallized for M = Ta, but almost amorphous for M = Nb. The Rietveld refinement confirmed that the intercalated tantalate, Li2CuTa3O9, adopts a rhombohedrally distorted perovskite structure with a = 5.4896(8) Å, α = 56.544(8)° and Z = 2 for the R3c space group. The Li and Cu atoms are statistically distributed over an identical crystallographic site with an atomic ratio of Li : Cu = 2 : 1. The coordination of the nearest-neighbor oxygen atoms around the (Li,Cu) site was changed from square-planar four-fold to triangular three-fold, accompanied by an intercalation reaction. This structural change could be reasonably explained as being due to the occurrence of a reduction of strong Jahn-Teller Cu2+ ions to Cu+ ions as a result of the lithium insertion.
  • Keisuke Umeda, Asao Nakamura, Fujio Toda
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2260-2267
    Published: 1993
    Released: August 09, 2006
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    Rh(terpy)23+ was used as a reduction catalyst for NAD+ into NADH in a photosensitized reaction system containing Ru(bpy)32+ (as a photosensitizer) and TEOA (triethanolamine) (as an electron donor). At pH 7.7, an effective NADH-formation (1.04 mM (1 M = 1 mol dm−3)) was observed after 90 min of light-irradiation, whereas a low yield of NADH at pH 6.5 or pH 10.0 (0.1 and 0.21 mM respectively) was obtained after 90 min of irradiation. Although the electron donor activity of TEOA is likely to be dependent on the pH conditions, the photosensitized reaction in the TEOA–Ru(bpy)32+–Rh(terpy)23+ system showed little pH influence in that growth in the absorbance at 440 nm, since the reduction of Rh(terpy)23+ at pH 7.7 is ca. 1.5-fold as large as at pH 6.3. The main reason for the NADH-formation dependence on the pH was found to be caused by the dependence of the catalytic activity of the reduced form of Rh(terpy)23+ on the pH conditions. In addition, the IR spectrum of Rh(terpy)23+ reduced at pH 8.0 shows a peak due to rhodium-hydride stretching (2100 cm−1), whereas that Rh(terpy)23+ reduced at pH 10.0 and/or pH 6.5 shows no peak in that region of wavenumbers. These results indicate that the reduction of NAD+ into NADH in the photosensitized reaction system is catalyzed by Rh(terpy)23+ according to hydride-transfer route.
  • Ryoji Yanagihara, Kaori Soeda, Sumito Shiina, Shuichi Osanai, Sadao Yo ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2268-2272
    Published: 1993
    Released: August 09, 2006
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    Aldoses were epimerized at C-2 by Ca2+ in aqueous or alcoholic basic solutions through a stereospecific [1-2] rearrangement of the carbon skeletons of the aldose. The skeletal rearrangement was confirmed by 13C NMR analysis of the reaction products. The reaction of [1-13C]- and [2-13C]- D-glucose afforded [2-13C]- and [1-13C]- D-mannose, respectively, as major products. The effects of metal ions, bases, and solvents were examined, and it was found that a high concentration of Ca2+ and a base (>pH 12.3) were especially effective for the present rearrangement. Separation of the reaction products was also effected by using Ca2+ cation-exchange chromatography. Thus, under the optimized conditions, D-mannose and D-lyxose, which are rare in nature and expensive, were easily obtained in high isolated yields from D-glucose and D-xylose, respectively.
  • Masafumi Yasunami, Takanori Hioki, Yoichiro Kitamori, Ikue Kikuchi, Ka ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2273-2282
    Published: 1993
    Released: August 09, 2006
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    1H- and 3H-Cyclopent[a]azulenes having an electron withdrawing group, such as a methoxycarbonyl or a cyano group, at the 9-position were synthesized from their dihydro compounds by means of bromination with NBS and succeeding dehydrobromination by refluxing in chloroform. Base-catalyzed condensation of these cyclopent[a]azulenes with carbonyl compounds afforded 1-methylene-1H- and 3-methylene-3H-cyclopent[a]azulene derivatives having an electron withdrawing group at the 9-position. The physical properties of these methylenecyclopent[a]azulenes are also discussed.
  • Jin-Shik Lee, Yuka Murakawa, Kentarou Fujino, Mitsuaki Narita
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2283-2288
    Published: 1993
    Released: August 09, 2006
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    The β-sheet-structure-stabilizing potential of 20 kinds of guest amino acids has been evaluated by solvent titration for the protected pentapeptide, Boc–X–Ala–Glu(OBzl)–Leu–Gly–OPac, described previously. It has been proved that the <SPβ> value was effective in evaluating the β-sheet-structure stability of protected tri- to heptapeptide in organic solvents. In order to widen the application range of the <SPβ> value, deca- and pentadecapeptides were synthesized by fragment condensation of pentapeptides. The β-sheet-structure-stabilizing potentials of individual guest amino acids determined from deca- and pentadecapeptides showed different results from the <SPβ> value. Circular dichroism showed that deca- and pentadecapeptides adopted helix and random coil structures in organic solvents. The helix structure influences the solvation mechanism of these protected peptides.
  • Ines Maria Costa Brighente, Leonor Rosa Vottero, Alberto Jose Terezani ...
    1993 Volume 66 Issue 8 Pages 2289-2293
    Published: 1993
    Released: August 09, 2006
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    Between pH 4 and pH 13, oxime formation from hydroxylamine with cyclohexanone and bicyclic ketones proceeds with rate limiting dehydration of the addition intermediate which is in equilibrium with the ketone and hydroxylamine. The dehydration step exhibits catalysis by oxonium ion (pH 4 to ca. 8), a pH independent pathway (pH 8 to ca. 10) and catalysis by hydroxide ion (pH ca. 10 to 13). The steric and electronic effects give important insights into the structure of the transition state of the mechanisms of oxonium ion, hydroxide ion catalyzed and spontaneous reaction.
  • Yukinori Nagao, Masahiro Takahashi, Yoshimoto Abe, Takahisa Misono, Mi ...
    1993 Volume 66 Issue 8 Pages 2294-2297
    Published: 1993
    Released: August 09, 2006
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    The 1,1-dialkoxy derivatives of 2,5-diphenylsilacyclopent-3-ene were prepared by a one-pot reaction of magnesium with (E,E)-diphenyl-1,3-butadiene and dialkoxydichlorosilanes. The trans content in each silacyclopentene was higher than the cis content. Hydrogenation of these silacyclopentenes gave the corresponding silacyclopentanes in high yields.
  • Chiaki Kuroda, Shigeru Shimizu, Takahiro Haishima, James Y. Satoh
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2298-2303
    Published: 1993
    Released: August 09, 2006
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    Synthesis of 10-epi-frullanolide (3) is reported via the intramolecular cyclization of ω-formyl-α-trimethylsilylmethyl-α,β-unsaturated ester. The cyclization precursor, ethyl (Z)-5-(2-formyl-1,3-dimethyl-2-cyclohexenyl)-2-trimethylsilylmethyl-2-pentenoate (17), was prepared from 2,6-dimethyl-2-cyclohexen-1-one through the dialdehyde monoacetal as the key intermediate. Cyclization of 17 with tetrabutylammonium fluoride produced the hydroxy ester having C(6α)–H and C(7β)–H, which was hydrolyzed, then subjected to Fujisawa’s lactonization to afford 3.
  • Katsuhiro Saito, Satoshi Suzuki, Tetsuya Watanabe, Kensuke Takahashi
    1993 Volume 66 Issue 8 Pages 2304-2308
    Published: 1993
    Released: August 09, 2006
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    Reactions of a cyclic C7H6-system, a tautomer of 1,2,4,6-cycloheptatetraene and 2,4,6-cycloheptatrienylidene, with tropone derivatives and 8,8-dicyanoheptafulvene afforded exo-[4π+2π] cycloadducts. Similar reactions with 1,3,5-cycloheptatriene derivatives gave exo-[6π+2π] cycloadducts. These reactions are considered to proceed through zwitter ionic intermediates containing tropylium ion moieties.
  • Mikio Ouchi, Takashi Araki, Tadao Hakushi, M. Elizabeth Sobhia, Kizakk ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2309-2314
    Published: 1993
    Released: August 09, 2006
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    The cation binding of dibenzo-20-crown-6 (2) and dibenzo-22-crown-6 (3) are determined by quantitative solvent extraction study. Compound 3 shows high Tl+/K+ and Tl+/Rb+ selectivity. The crystal structure of 3 is reported. Crystal data: monoclinic (P21/c), a = 7.328(1), b = 17.395(4), c = 8.939(1) Å, β = 102.78(1)°, Z = 2, R = 0.049 for 2122 reflections. The macrocycle shows a crystallographic center of symmetry with elliptical arrangement of the heteroatoms stabilized by possible C–H···O dipolar attractions.
  • Tadashi Hanaya, Kiyomi Yasuda, Hiroshi Yamamoto, Hiroshi Yamamoto
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2315-2322
    Published: 1993
    Released: August 09, 2006
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    The addition of dimethyl phosphonate to five kinds of 6-O-tosyl-hexofuranos-5-uloses 3ae (α- D-xylo, α- D-ribo, β- D-arabino, α- D-lyxo, and β- D-ribo) in the presence of DBU, followed by the catalytic hydrogenolysis in the presence of Raney-Ni (W-4), afforded (5S)- and (5R)-5,6-dideoxy-hexofuranose derivatives in the ratios of 1 : 0—2 : 1, depending upon the kinds of substituents on the β-side of the furanose ring of the intermediate 5,6-dideoxy-hex-5-enofuranoses. A P-in-the-ring sugar analogue of L-fucose type, 5,6-dideoxy-5-hydroxyphosphinyl- L-galactopyranoses, was efficiently prepared from 3-O-benzyl-5,6-dideoxy-1,2-O-isopropylidene-5-dimethoxyphosphinyl-α- L-galactofuranose readily obtained by the selective preparation mentioned above.
  • Hiroyuki Higuchi, Hiroyuki Yamamoto, Juro Ojima, Gaku Yamamoto
    1993 Volume 66 Issue 8 Pages 2323-2329
    Published: 1993
    Released: August 09, 2006
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    Synthesis of 7,8:13,14-dibenzo-2,9,11-trisdehydro[16]annulene-1,4-dione is described. Attempts to prepare diaza[18]annulene derivatives by ring expansion of the dibenz[16]annulenedione and its dimethyl analog are also described. Examination of 1H NMR spectra indicates that the dibenz[16]annulenedione shows no ring current effect.
  • Kazuko Takahashi, Takayasu Nihira, Masaaki Yoshifuji, Kensuke Tomitani
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2330-2334
    Published: 1993
    Released: August 09, 2006
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    Conjugation-extended tetrathiafulvalene analogues, 2,5-bis(1,4-dithiafulven-6-yl)thiophene (2a), 2,5-bis[2,3-bis(methoxycarbonyl)-1,4-dithiafulven-6-yl]thiophene, and 2,5-bis(1,4-dithiafulven-6-yl)furan, involving an aromatic heterocyclic linking group have been synthesized by the Wittig condensation reaction of 2,5-thiophene- and 2,5-furandicarbaldehydes with 1,3-dithiol-2-ylidenetributylphosphorane and its 4,5-bis(methoxycarbonyl) derivative. The electrochemical redox properties of these compounds in solution have been investigated by cyclic voltammetry in order to evaluate the effect of the linking group on the donating ability and the thermodynamic stability of the radical cations. Whereas the radical cations are not so stable, complexes of 2a with 2,3-dichloro-5,6-dicyano-p-benzoquinone and iodine were found to show relatively high conductivities ((1.0—1.1) × 10−3 S cm−1) on a compressed pellet at room temperature.
  • Takeo Kanai, Yasunobu Kai, Nobuaki Sato, Toshihiko Naito, Takashi Kami ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2335-2338
    Published: 1993
    Released: August 09, 2006
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    (Z)-2-(5-Amino-1,2,4-thiadiazol-3-yl)-2-[(fluoromethoxy)imino]acetic acid (2), a useful chemical modifier of cephalosporin antibiotics, was efficiently synthesized from 2-[(fluoromethoxy)imino]-1,3-propanedinitrile. The stereochemical structure of 2 was unambiguously determined by X-ray crystallography.
  • Tsuyoshi Satoh, Kazuko Oguro, Jun-ichi Shishikura, Naomi Kanetaka, Rei ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2339-2347
    Published: 1993
    Released: August 09, 2006
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    A method for synthesizing carboxylic acids and their derivatives from aldehydes and ketones via α-chloro-α-sulfonyl ketones is described. Acyclic α-chloro-α-sulfonyl ketones were synthesized from aldehydes and 1-chloroalkyl p-tolyl sulfoxides with carbon–carbon coupling in good overall yields. Cyclic α-chloro-α-sulfonyl ketones were synthesized from cyclic ketones in three steps in high overall yields. The Favorskii rearrangement of both acyclic- and cyclic α-chloro-α-sulfonyl ketones with sodium hydride in the presence of amine gave β-sulfonyl amides with skeletal rearrangement in good to excellent yield. Amides and α,β-unsaturated amides were synthesized from the β-sulfonyl amides. Treatment of the cyclic α-chloro-α-sulfonyl ketones with alkoxides and hydroxide gave carboxylic esters and acids with cleavage of the ring in good to excellent yields.
  • Katsukiyo Miura, Koichiro Oshima, Kiitiro Utimoto
    1993 Volume 66 Issue 8 Pages 2348-2355
    Published: 1993
    Released: August 09, 2006
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    Treatment of 1,6-dienes with tris(trimethylsilyl)silane in the presence of Et3B or α,α′-azobis(isobutyronitrile) afforded 3,3-bis(trimethylsilyl)-3-silabicyclo[3.3.0]octanes in addition to monocyclized cyclopentanes. Bicyclization of 1,6-enynes provided the corresponding 3-silabicyclo[3.3.0]oct-1-enes.
  • Katsukiyo Miura, Koichiro Oshima, Kiitiro Utimoto
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2356-2364
    Published: 1993
    Released: August 09, 2006
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    Triethylborane induced radical addition of various organosilanes (R3SiH) to acetylenes has been studied. Among them, tris(trimethylsilyl)silane (TTMSS) proved to be the best reagent for the hydrosilylation of acetylenic compounds in terms of yield and stereoselectivity. For instance, reaction of 1-dodecyne with TTMSS at room temperature for 3 h under Et3B catalyst provided (Z)-1-tris(trimethylsilyl)silyl-1-dodecene selectively in 98% yield. The stereochemical course of reduction of alkenyl iodides with TTMSS–Et3B or n-Bu3SnH–Et3B has been examined. Treatment of 1-dimethylphenylsilyl-2-iodo-1-dodecene with TTMSS–Et3B at room temperature afforded (Z)-1-dimethylphenylsilyl-1-dodecene selectively (Z/E > 30/1). On the other hand, treatment with n-Bu3SnH-Et3B gave (E)-1-dimethylphenylsilyl-1-dodecene exclusively.
  • Takashi Ito, Tohru Yoden
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2365-2370
    Published: 1993
    Released: August 09, 2006
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    [Mo(η5-MeCp)2H2] (3) (MeCp = C5H4Me) which was prepared by the reaction of MoCl5 with Na(MeCp) in the presence of NaBH4 was treated with p-toluenesulfonic acid (TsOH) to give [Mo(η5-MeCp)2H(OTs)]. Reactions of 3 with allyl alcohol in the presence of TsOH yielded [Mo(η5-MeCp)2(η3-C3H5)]+TsO whereas the similar reaction with 2-methyl-2-propen-1-ol yielded . When the reactions of 3 with protonic acid HA (HA = TsOH and AcOH) were carried out in the presence of acetone or 4-t-butylcyclohexanone, [Mo(η5-MeCp)2A2] were formed accompanied by the reduction of ketones to the corresponding alcohols. The results are compared with the similar reactions with cyclopentadienyl analog of 3.
  • Kazuhisa Nakanishi, Kazuhiko Mizuno, Yoshio Otsuji
    1993 Volume 66 Issue 8 Pages 2371-2379
    Published: 1993
    Released: August 09, 2006
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    Photoreactions of 1,2- and 1,4-dicyanobenzenes (o- and p-DCB) with allylic silanes, germanes, and stannanes in acetonitrile were studied under various conditions. In these photoreactions, one of cyano groups of o- and p-DCB was replaced by allylic groups. With trimethyl(3-methyl-2-butenyl)silane, -germane, and -stannane, the photosubstitution occurred at both α- and γ-positions of the allylic moiety in a constant ratio, regardless of the kinds of metals. 1,3-Dicyanobenzene (m-DCB) was less reactive to the photosubstitution reaction. The reactivity of group 14 organometallic compounds increased in the order: Si- < Ge- < Sn-compounds. The photoreactions were sensitized by aromatic hydrocarbons such as phenanthrene and triphenylene, and also accelerated by adding Mg (ClO4)2 and alkylbenzenes. Quantum yields for the formation of the substitution products increased with decreasing oxidation potentials of group 14 organometallic compounds. A key step for the photoreactions is the reaction of radical anions of dicyanobenzenes with allylic radicals that are generated by cleavage of radical cations of group 14 organometallic compounds. The mechanistic features of these photoreactions are discussed.
  • Koji Kondo, Katsuaki Kojima, Nobumasa Ishida, Masahiro Irie
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2380-2384
    Published: 1993
    Released: August 09, 2006
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    The synergistic effects of 2,2′-bipyridyl and potassium hexacyanoferrate(II) on the plating rate and the deposit quality were examined in the triethanolamine (TEA) electroless copper bath. The simultaneous addition of 2,2′-bipyridyl and potassium hexacyanoferrate(II) enhanced not only the plating rate but also the foil quality. The elongation of the foil produced in the TEA bath containing these two additives was 10 times larger than that produced in the bath containing only 2,2′-bipyridyl. The analysis based on the adsorption model revealed that the simultaneous addition of 2,2′-bipyridyl and potassium hexacyanoferrate(II) increases the respective adsorption equilibrium constants. From the analysis, the synergistic effects was attributed to the adsorption of 2,2′-bipyridyl and potassium hexacyanoferrate(II) on the surface with mutual interactions.
  • Keiji Miki, Yoshiki Sato
    1993 Volume 66 Issue 8 Pages 2385-2390
    Published: 1993
    Released: August 09, 2006
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    A biomimetic model of a monooxygenase enzyme was designed and synthesized on a silica surface using a facile procedure, for the purpose of direct functionalization of hydrocarbons. Immobilization and isolation of simple and bulky forms of iron tetraphenylporphyrin was accomplished by coordinative ligation to anchored imidazolyl groups in hydrophobic cavities formed by alkyl chains attached to the surface. The synthesized catalyst was dispersed in an aqueous solution with alkenes. The substrates were catalytically epoxidized by H2O2 as the oxygen donor in the presence of imidazole. The high catalytic activity for the epoxidation of alkenes is discussed with respect to the characteristics of the novel catalyst structure and of the applied reaction system.
  • Shigeru Sugiyama, Kazuaki Shimodan, Akira Ookubo, Naoya Shigemoto, Hir ...
    1993 Volume 66 Issue 8 Pages 2391-2395
    Published: 1993
    Released: August 09, 2006
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    Various zirconia were prepared from ZrOCl2·8H2O by the addition of aqueous ammonia and potassium hydroxide; the effect of the catalyst preparation on the oxidative coupling of methane over zirconia was studied. The selectivity to such C2 compounds as ethylene and ethane was strongly influenced by the pH of the preparative solution of ZrOCl2·8H2O, NH3 aq, and KOH, as well as the sequence of the addition of each hydroxide during the preparation of the catalyst.
  • Takayuki Ohmae
    1993 Volume 66 Issue 8 Pages 2396-2397
    Published: 1993
    Released: August 09, 2006
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    Coalescence, rearrangement, and splitting reactions of fullerenes are examined by use of a soap bubble model, where fullerenes are replaced by soap bubbles of a perfectly elastic body, to yield the predictions of the modes of these processes.
  • Masayasu Iida, Yasuko Miyagawa, Sachiko Kohri
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2398-2401
    Published: 1993
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    The NMR peak of 59Co(III) cationic complexes shifts upfield upon interacting with anions when the interaction is mainly electrostatic; it shifts downfield when the hydrophobic interaction acts additively with the electrostatic interaction. These trends are enhanced in micellar solution systems.
  • Shuichi Hamada, Yoshiyuki Kudo, Hiroaki Matsuda
    1993 Volume 66 Issue 8 Pages 2402-2405
    Published: 1993
    Released: August 09, 2006
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    Uniform spherical particles of crystalline lanthanum(III) carbonate hydroxide were prepared by aging at 100 °C the corresponding 1,2-ethanediamine complex solution in the presence of carbonate ion under specified conditions. The latter anions were generated from a mild oxidation of the ligand with nitrate ions present. The carbonate hydroxide particles were completely converted into the oxides at 900 °C without deformation.
  • Seiji Sawamura, Shigeo Yasuhara, Shigeru Sugi, Nobuaki Egoshi
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2406-2408
    Published: 1993
    Released: August 09, 2006
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    The solubility (ms) of sodium bromide (NaBr·2H2O) in water was measured at 283.15—313.15 K and 0.1—300 MPa. The ms decreases with increasing pressure and the coefficient, θ ( = (∂ms/∂p)T/ms), is −10 × 10−5 MPa−1 at 298.15 K and 0.1 MPa. This sign of θ is opposite to that (7 × 10−5 MPa−1) calculated using a thermodynamic equation.
  • Tetsuo Miyazaki, Hiroyuki Morikita
    1993 Volume 66 Issue 8 Pages 2409-2411
    Published: 1993
    Released: August 09, 2006
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    The ESR linewidths of H(D) atoms, produced in γ-irradiated solid hydrogen, depend significantly upon the matrices of the hydrogen isotopes. The ESR linewidth has been calculated by considering the dipole interactions of the electron spin magnetic moments of a trapped hydrogen atom with the nuclear magnetic moments of the surrounding hydrogen nuclei in addition to the Fermi interactions. It is concluded from a comparison of the experimental ESR linewidths with the theoretical ones that the H atoms in solid H2 are trapped at substitutional sites, while the H(D) atoms in solid HD and D2 are trapped at interstitial octahedral sites.
  • Osamu Kikuchi, Kaoru Yamaguchi, Kenji Morihashi, Yukihiro Yokoyama, Mi ...
    1993 Volume 66 Issue 8 Pages 2412-2414
    Published: 1993
    Released: August 09, 2006
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    The interactions between metal cations, Li+, Na+, K+, Be2+, Mg2+, Ca2+, and Al3+ and nuleophilic molecules, NH3, H2O, HF, PH3, H2S, and HCl were calculated by the ab initio method with the MIDI-4 basis set and were analyzed on the basis of the molecular electrostatic potential (MEP) maps of the nucleophilic molecules. The position where each cation is expected to be trapped by the nucleophilic molecule can fairly be estimated as the distance from the MEP minimum point using the ionic radius of the cation, irrespective of the nucleophiles and cations.
  • A. Premadas
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 8 Pages 2415-2418
    Published: 1993
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    A simple, rapid and quantitative anion-exchange separation of microgram to milligram quantities of thorium has been achieved from milligram quantities of niobium, tantalum, and titanium in citric acid-nitric acid medium. This method is successfully applied for the separation and estimation of thorium in niobite-tantalite type minerals. Sample (0.500 g) is fused with ca. 8 g KHSO4and is taken in ca. 7% citric acid medium. To a suitable aliquot ca. 8 M (1 M = 1 mol dm−3) nitric acid acidity is maintained in ice cold condition, and is passed through a column of Dowex-lX8 (100—200 mesh size). Thorium is eluted with ca. 6 M HCl and estimated spectrophotometrically with arsenazo III. The RSD obtained by this method is 2—3%.
  • Yoshio Takasu, Fuminori Kaneko, Tsuyoshi Tsutsui, Mine Nakagawa, Mitsu ...
    1993 Volume 66 Issue 8 Pages 2419-2421
    Published: 1993
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    Ultrafine palladium particles supported on powdery active carbon have been characterized by high-resolution scanning electron (secondary and reflection electron images) and transmission electron microscopies. The former was advantageous for the simultaneous observation of metal catalyst particles (smaller than 1.5 nm in diam.) as well as the surface morphology of their support.
  • Koji Waki, Ayako Tani, Tamaki Kato, Haruhiko Aoyagi
    1993 Volume 66 Issue 8 Pages 2422-2425
    Published: 1993
    Released: August 09, 2006
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    Two simplified peptides of PA1-14, which corresponds to the N-terminal 1-14 residues of adrenodoxin precursor, were synthesized and examined by circular dichroism and dye leakage measurements. Both peptides showed a tendency to form α-helices and exhibited moderate dye leakage.
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