Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 62 , Issue 4
Showing 1-50 articles out of 87 articles from the selected issue
  • Yasuzo Sakai, Kenichi Sato, Ikuko Ito, Fujio Takahashi
    1989 Volume 62 Issue 4 Pages 975-978
    Published: 1989
    Released: June 27, 2006
    JOURNALS FREE ACCESS
    In order to elucidate the mechanism by which phenylglyoxylic acid (PGA) is reduced electrochemically in the presence of strychnine (SC) to form mandelic acid (MA), which exhibits an optically active property, conductometric studies were carried out. The formation of a 1:1 complex between PGA (or MA) and SC was suggested from the results that equimolar mixture of PGA (or MA) and SC showed a maximum decrease of conductivity. Equilibrium constants of the 1:1 complex of PGA–SC or MA–SC were determined from the results of conductivity measurements at various temperatures. The thermodynamic data were calculated. ΔH and ΔS were found to be +22 kJ mol−1 and +1.1×102 J K−1 mol−1 for both the PGA–SC complex and MA–SC complex.
  • Akira Imamura, Kehong Ye, Masahiro Taketoshi
    1989 Volume 62 Issue 4 Pages 979-984
    Published: 1989
    Released: June 27, 2006
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    A localized molecular orbital method for the investigation of the ionized state of polymers is presented. It is based on the Crystal Orbital Method(CO). By performing a super-cell method and Edmiston and Ruedenberg’s LMO method, the Bloch function was transformed into a nearly completely localized Wannier function. Furthermore, the calculation of the configuration interaction was introduced to obtain more reasonable results. The present method was applied to polyacetylene (PA), polyethylene (PE), and polypropylene (PP). Ionization potentials of these polymers were calculated and compared with experimental and other theoretical results. All the calculations were performed using the CNDO/S approximation.
  • Haruo Nakayama, Hiromi Kuwata, Norikazu Yamamoto, Yutaka Akagi, Hirosh ...
    1989 Volume 62 Issue 4 Pages 985-992
    Published: 1989
    Released: June 27, 2006
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    The solubilities of a series of symmetrical tetraalkylammonium salts, R4NX (R=CH3n-C8H17, including i-C4H9 and i-C5H11; X=Cl, Br, I, NO3, and ClO4), in water have been determined over the temperature range between 5 and 45 °C. The solubilities of these salts were found to be strongly dependent upon both the chain length of R of the R4N+ cation and upon the partial molar volume of the X anion. It has been concluded that these solubilities are closely related with the stability of a “cage-like” water structure, which is presumably formed around the R4N+ cation in the solution. A thermodynamic interpretation of the solubility of the R4NX salts was made by using some thermodynamic properties obtained by a differential scanning calorimetry, together with the enthalpy of the solution calculated from the temperature dependence of the solubility.
  • Yoshimasa Hoshino, Ryouta Takahashi, Kunio Shimizu, Gen P. Satô, ...
    1989 Volume 62 Issue 4 Pages 993-998
    Published: 1989
    Released: June 27, 2006
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    A useful method for computing the rate constants of reversible, first-order, triangular network reactions (B1\ ightleftarrowsB2, B2\ ightleftarrowsB3, B3\ ightleftarrowsB1) is developed. It gives the best-fit set of the rate constants from the experimental data of the equilibrium constants and the mole fraction-time curves through an iterative least-squares method. This type of reaction can be classified into three categories for different shapes of the mole fraction-time curves. The method was successfully applied to determining the rate constants of the rearrangement reactions among the three isomers of [Ru(acac)(tfpb)2] (acac=acetylacetonate ion, tfpb=4,4,4-trifluoro-1-phenyl-1,3-butanedionate ion) in N,N-dimethylformamide at 90 °C. The direct conversion between the de,fc-bis(tfpb) isomer and the cf,ed-bis(tfpb) isomer was forbidden. The twist mechanisms are incompatible with this fact.
  • Yasuyuki Takeda, Rie Kohno, Yoshihiro Kudo, Naoaki Fukada
    1989 Volume 62 Issue 4 Pages 999-1003
    Published: 1989
    Released: June 27, 2006
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    Formation constants in water of 1:1 benzo-18-crown-6 (B18C6)–metal ion complexes and the B18C6 solubility in water were determined at 25 °C by conductometry or potentiometry with ion-selective electrodes and spectrophotometry, respectively. The selectivity sequences of B18C6 for metal ions in water are Pb2+>Ba2+>Sr2+>Ag+>K+>Tl+>Na+>Rb+. In each case of alkali and alkaline earth metal ions, the more closely a metal ion fits into the B18C6 cavity, the more stable is the B18C6–metal ion complex. Although the solvation power of water for an alkali metal ion is not the largest of all solvents, the formation constant of a given B18C6–alkali metal ion complex in water is by far the smallest of all solvents. The transfer activity coefficients (γ) from water to nonaqueous solvents of the B18C6–metal ion complexes were then calculated from the formation constants of the B18C6 complexes, γ values of B18C6 (obtained from solubilities of B18C6), and γ values of the uncomplexed metal ions. The γ value of B18C6 is larger than those of B18C6–alkali metal ion complexes. This shows that when B18C6 forms a complex with an alkali metal ion, the B18C6 complex becomes more soluble in nonaqueous solvents than in water, compared with uncomplexed B18C6.
  • Sadamu Yamagata, Ryo Baba, Akira Fujishima
    1989 Volume 62 Issue 4 Pages 1004-1010
    Published: 1989
    Released: June 27, 2006
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    The reaction mechanism of the photocatalytic oxidation of 2-ethoxyethanol (Ethyl Cellosolve, EtOCH2CH2OH) on TiO2 powder was investigated by gas chromatography-mass spectrometry (GC-MS), infrared (IR) spectroscopy, and electron spin resonance (ESR) with spin trapping technique. Irradiation of TiO2 powder with UV light in the presence of EtOCH2CH2OH under air led to the formation of ethyl formate, ethanol, acetaldehyde and carbon dioxide. The main product, ethyl formate was different from the product through the reaction pathway proposed before for primary alcohols. It was also different from the product of electrolysis on Pt. Reaction mechanism is proposed based on IR and ESR studies.
  • Jun Nakauchi, Keiichi Sakashita, Yoshitaka Kageyama, Seiji Hayashi, Ke ...
    1989 Volume 62 Issue 4 Pages 1011-1016
    Published: 1989
    Released: June 27, 2006
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    The following series of novel ferroelectric liquid crystals, derived from normal alkyl esters of (R)-3-hydroxybutanoic acid, have been synthesized, and several factors determining their mesomorphic properties have been investigated:
    (Remark: Graphics omitted.)
    The smectic polymorphism for these compounds with three aromatic rings is strongly affected by the position and kind of the linkage groups in the core. The effects of the lengths of the two terminal chains (m,n) and the linkage groups in the core on the thermal stability of the smectic A and chiral smectic C phases have been discussed from the structural points of view.
  • Shuichi Hamada, Yoshiyuki Kudo, Takanobu Matsumoto
    1989 Volume 62 Issue 4 Pages 1017-1022
    Published: 1989
    Released: June 27, 2006
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    Monodispersed α-iron(III) oxide (hematite) particles were produced from an iron(II) chloride/2,2′-bipyridine system in the presence of potassium nitrate at elevated temperatures, 90–100 °C. An aqueous solution of 2,2′-bipyridineiron(II) complex directly gave spherical hematite particles (0.35 μm in size with a relative standard deviation of 0.09) under the conditions of 1.0×10−3 mol dm−3 FeCl2, 3.0×10−3 mol dm−3 2.2′-bipyridine, 6.0×10−3 mol dm−3 HCl, and 5.0×10−2 mol dm−3 KNO3 at 100 °C for 8 h. The oxidation of iron(II) ions would be slower than the dissociation of the complex and precipitation during the course of aging. The hematite particles grew through the polynuclear layers mechanism. Iron(II) sulfate/2,2′-bipyridine mixed solutions were also capable of yielding monodispersed particles, though they were a mixture of hematite and α-iron(III) hydroxide oxide (goethite). The points of zero charge (PZC) of these particles were estimated as pH 7.7 and 7.5 for those obtained from the iron(II) chloride and sulfate/2,2′-bipyridine systems, respectively.
  • Takeo Ohsaka, Youko Takahira, Osamu Hatozaki, Noboru Oyama
    1989 Volume 62 Issue 4 Pages 1023-1031
    Published: 1989
    Released: June 27, 2006
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    The diffusion coefficients for the charge-transport processes through 9,10-dihydro-3,4-dihydroxy-9,10-dioxo-2-anthracenesulfonate (Alizarine Red S, 1)-incorporating cationic perfluoropolymer (CPFP) polyelectrolyte films on electrodes undergoing oxidation or reduction of two separate electroactive centers with different redox potentials, i.e., the two-electron reduction of 1 to 3,4,9,10-tetrahydroxy-2-anthracenesulfonate (2) and the two-electron oxidations of 2 to 1 and 1 to 3,4,9,10-tetrahydro-3,4,9,10-tetraoxo-2-anthracenesulfonate ( 3) were measured by potential-step chronoamperometry and chronocoulometry. The apparent diffusion coefficients for 1 to 2, 2 to 1, and 1 to 3 processes where the first two processes are reversible and the 1 to 3 process is irreversible, represented as Dapprev(1→2), Dapprev(2→1) and Dappirrrev (1→3), respectively, decreased with increasing the concentration (Cfilm) of 1 (or 2) in the CPFP film, and for a given Cfilm they were found to be in the following order: Ds′>>Dapprev (1→2)∼Dapprev(2→1)>Dappirrev (1→3), where Ds′ represents the diffusion coefficients corresponding to the diffusion of supporting electrolyte ions coupled to electron transfer and molecular motion of reactant itself. It became apparent that the difference in Dapprev(1→2) (or Dapprev(2→1)) and Dappirrev (1→3) can be attributed to different contributions of electron exchange between electroactive centers to the overall charge-transport rates. The results demonstrate that the contributions from molecular motion of reactant itself and electron exchange between reactants to the overall charge-transport rates can be estimated depending upon which redox center is employed in an electrochemical measurement of diffusional rates.
  • Kenji Ikeda, Motoharu Ishikawa, Masaaki Yasuda, Kunio Esumi, Kenjiro M ...
    1989 Volume 62 Issue 4 Pages 1032-1036
    Published: 1989
    Released: June 27, 2006
    JOURNALS FREE ACCESS
    The physicochemical properties of the α,ω-type (bolaform) surfactant, bis(triethylammonium) 1,20-eicosanediyl disulfate (α,ω C20N2Et6), in aqueous solution have been investigated by means of surface tension, electrical conductivity, dye solubilization and time-resolved fluorescence quenching. The critical micelle concentration of α,ω C20N2Et6 was 1–1.3×10−3 mol dm−3. The micelle ionization degree of the surfactant was larger than a conventional surfactant having the same head group. From surface tension measurements, the molecular area of α,ω C20N2Et6 at the air–water interface was found to be about twice as large as that of a normal type surfactant, such as sodium dodecyl sulfate (SDS). This reveals that α,ω C20N2Et6 probably forms vertical looping (“wicket-like” conformation) at the air–water interface. By time-resolved fluorescence quenching measurements, the aggregation number of α,ω C20N2Et6 micelle was found to be strongly dependent on the concentration, but only slightly dependent on the temperature. At low concentrations the aggregation number is close to half that corresponding to a normal type surfactant having a chain length that is that of the bolaform. The solubilizing power of a micellar solution of α,ω C20N2Et6 toward Orange OT was 7.6×10−3 mol of dye per mol of surfactant, that is, a value smaller than that of SDS.
  • Kunio Esumi, Yuki Asano, Yuichi Sakamoto, Kenjiro Meguro
    1989 Volume 62 Issue 4 Pages 1037-1041
    Published: 1989
    Released: June 27, 2006
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    The interactions between disodium 1,14-tetradecanediyl disulfate (α,ωC14) and sodium dodecyl sulfate (SDS) or poly(oxyethylene) nonyl phenyl ether (NP 7.5) on α-alumina have been studied by measuring the zeta potential, the mean particle size, the amounts of surfactants adsorbed, and the fluorescence spectra of pyrene. When α,ωC14, SDS, or NP 7.5 as a second additive is added to alumina previously flocculated by the addition of SDS or α,ωC14, as a first additive, the flocculated alumina redisperses in the α,ωC14–SDS and α,ωC14–NP 7.5 systems. For the α,ωC14–SDS and α,ωC14–NP 7.5 systems, the redispersion of alumina proceeds in such a manner that the hydrophobic parts of SDS or NP 7.5 are in contact with the α,ωC14-coated alumina and the hydrophilic polar groups direct out to aqueous solution, resulting in the formation of mixed bilayers on the alumina, while for the α,ωC14–SDS system the adsorption of SDS on the α,ωC14-coated alumina is not enough to attain the redispersion of alumina. The measurement of the ratio I1I3 of intensities of the first and third vibrionic bands of the pyrene monomer fluorescence spectra indicates that pyrene is solubilized in a much lower polar site for the α,ωC14–SDS mixed bilayer than for the mixed bilayer of α,ωC14–NP 7.5.
  • Toshio Uchihara, Hirohisa Abe, Michio Matsumura, Hiroshi Tsubomura
    1989 Volume 62 Issue 4 Pages 1042-1046
    Published: 1989
    Released: June 27, 2006
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    The CdS1−xSex mixed-crystal powder was prepared for the purpose to reduce the band gap of CdS and expand the effective wavelength region of the photocatalyst. Hydrogen evolution was observed from an aqueous solution of 1 M sodium sulfite by use of the mixed-crystal photocatalyst loaded with platinum under illumination at wavelengths longer than 520 nm, where neither the platinum-loaded CdS nor CdSe photocatalyst is active. However, when the mixed-crystal catalysts were illuminated at wavelengths longer than 390 nm or with an AM 1 solar simulator, the rate of the hydrogen evolution was lower than that of CdS. The energy levels of the electronic bands in the mixed-crystals have been clarified from the results of the electrochemical studies, and the fact that the mixed-crystal powder has lower photocatalytic activity than CdS powder has been ascribed to the downward shift of the conduction band edge. These findings are useful in designing photocatalysts for hydrogen production.
  • Etsu Yamada, Eiichiro Nakayama, Masanori Sato
    1989 Volume 62 Issue 4 Pages 1047-1052
    Published: 1989
    Released: June 27, 2006
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    The extraction behavior of cobalt(II) into 1,1,2,2-tetrachloroethane (TCE) with 8-quinolinol (HQ) from an aqueous solution in the presence of various inorganic anions (X) such as perchlorate, nitrate, and chloride ions was studied themodynamically. The extraction equation can be written as
    2Co2++6HQ(o)+X\ ightleftarrowsCo2Q3(HQ)3+(o)+X(o)+3H+
    The ion-pair of the binuclear complex (complex ion-pair) dissociates to a complex cation and an inorganic anion in the organic phase. The extraction constant increases in proportion to the radius of the counter anion. Changes in the enthalpy and entropy are negative for the overall extraction of cobalt with 8-quinolinol. These thermodynamic parameters were compared with those of zinc and cadmium. The temperature effect on the extraction behavior of cobalt with 8-quinolinol was also investigated in a chloroform system for comparison.
  • Guilin Ma, Tomomi Hibino, Masaaki Kojima, Junnosuke Fujita
    1989 Volume 62 Issue 4 Pages 1053-1056
    Published: 1989
    Released: June 27, 2006
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    The rates of the base-catalyzed proton exchange (deuteration, kD) and isomerization (epimerization, kep) at the chiral amine nitrogen centers of [Co(acac or ox)2(Me-en or Me3en)]+or− in aqueous solutions were measured at 34.0 °C, and the results were compared with one another and with those of related complexes. The deuteration rate is affected more by the nature of coexisting ligands than the overall charge on the complex. The uninegative ox complexes have larger kD values than the unipositive acac complexes. The kep values of the ox complexes are ca. 104 times as large as those of the acac complexes. For both ox and acac complexes, the complexes with Me3en have larger kD and kep values than the complexes with Me-en. The deuteration rates are ca. 104–105 and ca. 102 times greater than the inversion rates for the acac and ox complexes, respectively.
  • Yasuhiko Yukawa, Shin Nakagome, Hiromitsu Yamaguchi, Yoshie Inomata, T ...
    1989 Volume 62 Issue 4 Pages 1057-1060
    Published: 1989
    Released: June 27, 2006
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    An X-ray diffraction study of the title complex has been carried out, along with spectroscopic measurements and thermal analyses. The crystal is orthorhombic, space group P212121, Z=4, a=9.978(2), b=12.624(3), c=7.129(1) Å, U=898.0(3) Å3. Block-diagonal least-squares refinements have led to the final R value of 0.032. The structure consists of a one-dimensional polymer chain bridged by a carboxylato group of an N,N-diethylglycinato ligand. One oxygen atom in the carboxylato group is coordinated to two copper atoms, and the other is coordinated to one of these two copper atoms. This is the same bridging form as in aquachloro(4-hydroxy-L-prolinato)copper(II). The copper atom reveals a distorted five-coordination: the copper atom is surrounded by three carboxylato oxygen atoms, one nitrogen atom, and one chlorine atom. The infrared spectra of the title complex and of aquachloro(4-hydroxy-L-prolinato)copper(II) both show the characteristic pattern at the peaks assigned to the vibrations of the carboxylato group. The peaks can be an indicator of the bridging form.
  • Isao Sanemasa, Masaya Kumamaru, Kazunari Ishibashi, Toshio Deguchi
    1989 Volume 62 Issue 4 Pages 1061-1064
    Published: 1989
    Released: June 27, 2006
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    The solubility in water at 25 °C of binary mixed solutes, combinations of biphenyl and naphthalene with benzene, cyclohexane, and 1-octanol, was measured using a shake-flask method. As a function of biphenyl or naphthalene mole fraction, activity coefficients of biphenyl and naphthalene in benzene, cyclohexane, and 1-octanol, and those of benzene in biphenyl–benzene and naphthalene–benzene binary systems have been determined.
  • Hiroshi Kawaguchi, Hideko Miyamoto, Tomoharu Ama, Takaji Yasui
    1989 Volume 62 Issue 4 Pages 1065-1069
    Published: 1989
    Released: June 27, 2006
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    Isomerization reactions among four geometrical isomers (pink, violet, brown, and light-brown) of [Co(ida)(edma)] were studied in a basic aqueous solution. In a reaction of (−)554CD-pink, three isomers of (+)563CD-violet, (+)565CD-brown (with a low optical purity), and racemic light-brown formed simultaneously. The major products in reactions of (+)563CD-violet and (+)565CD-brown were (+)565CD-brown and (+)563CD-violet, respectively. Light-brown mainly isomerized to brown at a rapid rate. Moreover, it was found that (+)563CD-violet racemized at a considerable rate. These stereoselective reactions are discussed in connection with those for [Co(edma)2]+ and [Co(ida)2].
  • Toshiaki Akagawa, Guilin Ma, Nahomi Suzuki, Shigeru Ohba, Yue Ouyang, ...
    1989 Volume 62 Issue 4 Pages 1070-1077
    Published: 1989
    Released: June 27, 2006
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    The molecular structures of three racemic pairs of diastereomers, ΔRR(ΛSS)-, ΔSR(ΛRS)-, and ΔSS(ΛRR)-trans(N-Ph, N-Ph)-[Co(pd)(Ph-en)2]2+ and of one racemic pair of diastereomers, ΔSS(ΛRR)-trans(N-Ph, N-Ph)-[Co(ox) (Ph-en)2]+ (pd=2,4-pentanedionate ion, ox=oxalate ion, Ph-en=N-phenylethylenediamine) were determined by the single-crystal X-ray diffraction method in order to study the intramolecular interactions between π-systems in the ligands. For the ΔSS(ΛRR)-isomer of [Co(pd)(Ph-en)2]2+, three kinds of crystal structures 3a, 3b, and 3c were investigated. The crystal data and final R values are: ΔRR(ΛSS)-[Co(pd)(Ph-en)2](ClO4)2·H2O (1), orthorhombic, Pbca, a=32.472(9), b=11.120(3), c=15.303(4) Å, V=5526(3) Å3, Z=8, R=0.065 for 2113 observed unique reflections. ΔSR(ΛRS)-[Co(pd)(Ph-en)2](ClO4)2 (2), orthorhombic, P212121, a=19.440(8), b=16.406(8), c=8.407(3) Å, V=2681(2) Å3, Z=4, R=0.038 for 2205 reflections. ΔSS(ΛRR)-[Co(pd)(Ph-en)2]Cl2·H2O (3a), monoclinic, P21c, a=12.475(3), b=11.590(2), c=19.054(4) Å, β=117.18(2)°, V=2450.6(9) Å3, Z=4, R=0.035 for 2164 reflections. ΔSS(ΛRR)-[Co(pd)(Ph-en)2](ClO4)Cl·H2O (3b), triclinic, P\bar1, a=11.847(5), b=13.584(4), c=8.367(2) Å, α=103.57(2), β=91.85(3), γ=84.25(3)°, V=1302.1(8) Å3, Z=2, R=0.087 for 1374 reflections. ΔSS(ΛRR)-[Co(pd)(Ph-en)2](ClO4)Cl (3c), triclinic, P\bar1, a=11.660(5), b=14.028(3), c=8.308(7) Å, α=108.00(8), β=101.57(9), γ=92.47(13)°, V=1258(3) Å3, Z=2, R=0.052 for 1118 reflections. ΔSS(ΛRR)-[Co(ox)(Ph-en)2] Br·6H2O (4), orthorhombic, Pna21, a=15.804(1), b=15.646(1), c=10.428(2) Å, V=2578.5(4) Å3, Z=4, R=0.065 for 1496 reflectios. The numbers of phenyl rings of the Ph-en ligands that overlap with the pd π system in the complex cation are 0, 1, and 2 for 1, 2, and 3 respectively. The ox ligand of 4 is ill-sandwiched by the two phenyl rings, whereas the pd ligand is well-sandwiched in 3a. The arrangements of the phenyl groups relative to the pd differ slightly from one another in the crystals of 3a, 3b, and 3c. The dihedral angles between the pd (or ox) and phenyl rings range from 25 to 35°.
  • Takashi Amagai, T. Ken Miyamoto, Hikaru Ichida, Yukiyoshi Sasaki
    1989 Volume 62 Issue 4 Pages 1078-1080
    Published: 1989
    Released: June 27, 2006
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    Two new gold(I) complexes linked to pyrimidines, (5-fluoro-2′-deoxyuridinato-N3)(triphenylphosphine)gold(I) (1) and [5-fluoro-1-(tetrahydro-2-furanyl)-2,4(1H,3H)-pyrimidinedionato-N3](triphenylphosphine)gold(I) (2) were synthesized and characterized by 31P, 1H NMR and IR spectra. The structure of 2 was determined by an X-ray diffraction method. A linear, two-coordination around gold(I) has been shown. In order to estimate the possible alteration of 1 and 2 in vivo, several factors such as the effect of pH, and reactions with thiol, thiophenol, and imidazole were examined.
  • Yoshio Fuchita, Katsuma Hiraki, Yasuko Kamogawa, Miho Suenaga, Kazutak ...
    1989 Volume 62 Issue 4 Pages 1081-1085
    Published: 1989
    Released: June 27, 2006
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    Palladium(II) acetate reacts with benzene in the presence of dialkyl sulfides at 70 °C to afford novel diphenyltripalladium(II) complexes of [(R1SR2)PhPd(μ-MeCO2)2Pd(μ-MeCO2)2PdPh(R1SR2)] (1a; R1=But, R2=CH2But: 1b; R1=R2=Bui: 1c; R1=R2=Pri: 1d; R1=R2=Et). Adducts, [Pd(MeCO2)2(ButSCH2But)2] and [Pd(MeCO2)2(SPri2)2], prepared by the reactions of palladium(II) acetate and the corresponding dialkyl sulfides in benzene at 5–10 °C, change to 1a and 1c, respectively, on heating in benzene at 70 °C. In contrast, reactions of palladium(II) acetate with toluene or thiophene in the presence of diisopropyl sulfide afford no isolable tolyl-or thienyl-palladium species, but coupling products, i.e. bitolyls or bithienyls, are detected by GLC analysis. Treatment of 1b with styrene produces trans-stilbene, whereas 1c reacts with carbon monoxide as well as carbon dioxide to yield benzoic acid. When palladium(II) acetate and t-butyl phenethyl sulfide are heated at 80 °C in benzene, an adduct [Pd(MeCO2)2(ButSCH2CH2Ph)2] is formed, in sharp contrast with the case of benzyl t-butyl sulfide, which gives a cyclopalladated complex under the same reaction conditions.
  • Katsumi Yonemoto, Isao Shibuya, Kazumasa Honda
    1989 Volume 62 Issue 4 Pages 1086-1092
    Published: 1989
    Released: June 27, 2006
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    The reaction of 5-substituted 3-phenyl-1,4,2-dithiazolium salts with malononitrile gave not only 5-dicyanomethylene-3-phenyl-1,4,2-dithiazole and an isothiazole derivative, but 4-amino-5-cyano-2-(1-cyano-2-dialkylamino-2-mercaptovinyl)-6-phenylpyrimidines (6) and a butadiene derivative, depending on substituents at C-5 and bases used. The structure of 6 was confirmed by X-ray crystallographic analysis of its methylated derivative. These results are well explained by assuming three possible fission modes of the initial adduct: liberation of substituents at C-5 (Path A), ring opening-ring closure reaction (Path B), and fragmentation of dithiazole ring (Path C). On the other hand, 2-dialkylamino-4,5-diphenyl-1,3-dithiolium salts were allowed to react with malononitrile to afford 2-amino-3-cyano-5,6-diphenyl-1,4-dithiin (13) and 4-amino-3-cyano-2-dicyanomethylene-5,6-diphenyl-2H-thiin (14) as well as 2-dicyanomethylene-4,5-diphenyl-1,3-dithiole (12). In a separate experiment, both 13 and 14 were formed by the reaction of 12 with malononitrile. This pathway can be interpreted in terms of considerable contribution of polar structure of 12 due to the push–pull effect of sulfur atoms and cyano groups. Furthermore, the reaction of 2-substituted 4-phenyl-1,3-dithiolium salts with malononitrile also gave 2-dicyanomethylene-4-phenyl-1,3-dithiole and thiophene derivatives.
  • Akiko Nishida, Makoto Takeshita, Nobuaki Kawano, Shizuo Fujisaki, Shoj ...
    1989 Volume 62 Issue 4 Pages 1093-1096
    Published: 1989
    Released: June 27, 2006
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    Several 9-(2′-dimethylaminophenyl)-9-fluorenols (2) and 9-(2′-dimethylaminophenyl)fluorenes (3), which had electron-attracting or electron-releasing groups at 2- or 2,7-positions of the fluorene ring, were synthesized. The conformational equilibria (anti\ ightleftarrowssyn) of 2 and 3 in CDCl3 lay near to their syn sides. However, the equilibria of 2 in DMSO-d6 inclined to the anti side. By the addition of trifluoroacetic acid to the solution of 3 in CDCl3, anti-3 salts were formed and stabilized by the N–H···π interaction between the dimethylammonio group and the fluorene ring. In this case, the intensities of the N–H···π interaction were affected by the magnitudes of the π-electron density of the fluorene ring.
  • Kazuo Yamaguchi, Hitoshi Kuboniwa, Nobuya Murakami, Akira Hirao, Seiic ...
    1989 Volume 62 Issue 4 Pages 1097-1101
    Published: 1989
    Released: June 27, 2006
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    Seven ω-hydroxy carboxylic acids bearing 2–5 ether oxygens with or without aromatic rings and five ω-alkoxy carboxylic acids bearing 2–6 ether oxygens with aromatic rings were employed as carriers for the active transport of alkaline earth metal ions as well as alkali metal ions through 1,2-dichloroethane or 1-hexanol as an organic liquid membrane. The relatively hydrophobic ω-hydroxy and ω-alkoxy carboxylic acids (logP>7) exhibited a high M2+ transport ability and selectivity over M+ through 1,2-dichloroethane, regardless of the number of ether oxygen. However, a marked selectivity among alkaline earth metal ions (Mg2+, Ca2+, Ba2+) was not observed. The less hydrophobic carboxylic acids (logP<6) did not transport Ba2+ through 1,2-dichloroethane. Ba2+ transport ability of the hydrophobic acids through 1-hexanol was lower than that through 1,2-dichloroethane. Linoleic acid in the presence of oligo- and polyethylene glycols showed efficient Ba2+ transport through 1,2-dichloroethane, although a long-chain fatty acid was not able to transport Ba2+ by itself.
  • Masaaki Iwata, Hiroyoshi Kuzuhara
    1989 Volume 62 Issue 4 Pages 1102-1106
    Published: 1989
    Released: June 27, 2006
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    A new systematic route to threefold protected natural polyamines, spermidine, spermine, thermine, and thermospermine, was developed through alternate regioselective manipulation on the terminal primary amino groups, starting from N,N-phthaloyl-1,3-propanediamine hydrochloride (3). When 3 was tosylated at the amine terminal and the phthaloyl terminal was subjected to transformation to the formamido group followed by substitution at the tosyl terminal with, e.g., N-(4-bromobutyl)phthalimide, threefold protected spermidine was obtained in excellent yield. After hydrolysis of the formamido group to amine salt, a sequence of the reactions was satisfactorily repeated to afford various types of threefold protected natural tetramines.
  • Hiroshi Suginome, Yoshitaka Kurokawa
    1989 Volume 62 Issue 4 Pages 1107-1110
    Published: 1989
    Released: June 27, 2006
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    2,4-Dinitro-5α- and 5β-cholestan-3-ones were prepared by dinitration of the parent 3-ones by a modified standard method. Spectroscopy indicated that in ethanol these α,α′-dinitro ketones exist in their enol forms. Photolysis of these dinitro ketones in ethanol gave diosphenols arising from the removal of their two nitro groups. On the basis of the results of the irradiation of hypothesized intermediate obtained by synthesis, we suggest the path likely to lead to the removal of the nitro groups.
  • Tyo Sone, Yoshihiro Ohba, Hajime Yamazaki
    1989 Volume 62 Issue 4 Pages 1111-1116
    Published: 1989
    Released: June 27, 2006
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    Acyclic para-substituted phenol–formaldehyde oligomers (R=H, Me, n-Bu, t-Bu, and cyclohexyl; the number of phenol units=3–6) form host–guest complexes with various organic compounds. The inclusion property of the acyclic oligomers is greatly influenced by the p-substituents of phenol and the number of phenol units in the oligomers; for example, a) while the t-butyl tetramer is effective, the corresponding butyl tetramer has a poor ability for the complex formation, and b) the tetramers and pentamers are good hosts for organic compounds, forming 2:1 (host:guest) complexes in many cases.
  • Guo-Chi Zheng, Hiroshi Kakisawa
    1989 Volume 62 Issue 4 Pages 1117-1122
    Published: 1989
    Released: June 27, 2006
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    Salvilenone 1, a phenalenone diterpene isolated from the roots of Salvia miltiorrhiza Bunge, was synthesized in thirteen steps from resorcinol dimethyl ether. Dihydrophenalenol derivative 19, a key intermediate, was treated with aqueous hydrobromic acid to give salvilenone accompanied by the formation of a hydroxy diketone 20.
  • Chizuko Yatome, Toshihiko Ogawa, Toshihiko Ogawa, Hideki Hayashi
    1989 Volume 62 Issue 4 Pages 1123-1126
    Published: 1989
    Released: June 27, 2006
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    2-Carboxy-4′-dimethylaminoazobenzene (CDMAB) was reductively cleaved into its two component primary arylamines by Bacillus diaphorase together with NADH (pH 6.1, 25 °C). The reductive cleavage was found to proceed stoichiometrically by a spectrofluorometric assay of fluorescent o-aminobenzoic acid and a fluorescent product formed between N,N-dimethyl-p-phenylenediamine and fluorescamine. Parallel lines were obtained in Lineweaver–Burk plots of initial rate vs. CDMAB concentration for the reduction. This experimentally observed kinetic behavior is consistent with a reaction scheme in favor of the Ping Pong mechanism in which CDMAB is reduced by a reduced form of diaphorase. From a kinetic formula, the apparent Km(CDMAB), Km(NADH), and Vmax values are 2.14×10−5 mol dm−3, 7.35×10−5 mol dm−3, and 1.8×10−7 mol dm−3 min−1 per mg of protein, respectively.
  • Chung-gi Shin, Takumi Obara, Shuji Taniguchi, Yasuchika Yonezawa
    1989 Volume 62 Issue 4 Pages 1127-1135
    Published: 1989
    Released: June 27, 2006
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    Several kinds of N-free and protected N-carboxydehydrotyrosine anhydride (ΔTyr·NCA) derivatives, derived by both the cyclization of the corresponding N-benzyloxycarbonyldehydrotyrosine derivatives and the protection of the resulting ΔNCA, were employed for a one-pot dehydrooligopeptide (DHP) synthesis. As a result, various kinds of DHPs with a wide variety of combinations of sequences could be synthesized in fairly good yields. In addition, by utilizing the obtained information, two kinds of leucine-dehydroenkephalins containing a ΔTyr1 and both ΔTyr1 and ΔPhe4 residues were also synthesized.
  • Guan Rong Tian, Shigeru Sugiyama, Akira Mori, Hitoshi Takeshita, Miwak ...
    1989 Volume 62 Issue 4 Pages 1136-1142
    Published: 1989
    Released: June 27, 2006
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    Thermal cycloaddition reactions of 2,3-bis(methoxycarbonyl)-7-oxabicyclo[2.2.1]heptadiene with 2H-cyclohepta[b]furan-2-ones and 8,8-dicyanoheptafulvene gave [4+2]adducts exclusively. This mode is different from the reported [8+2]adduct formations for 2H-cyclohepta[b]furan-2-ones with enamines and alkoxyethenes. A consideration of the superjacent and subjacent orbitals effects of the MO calculations gave a better result in favor of [4+2]adduct formation. Thermolysis of cycloadducts gave the methylene derivatives of homobarrelenes.
  • Shigeru Sugiyama, Akira Mori, Nobuo Kato, Hitoshi Takeshita
    1989 Volume 62 Issue 4 Pages 1143-1146
    Published: 1989
    Released: June 27, 2006
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    The kinetic features of the [1,9] sigmatropy (with 2-benzyloxy-3-bromotropone) and the [3,3] sigmatropy (with 2-allyloxytropone and 2-[(3-methyl-2-butenyl)oxy]tropone) were investigated under various pressures (1 to 1600 bar). The activation volume of [1,9] sigmatropy was of the same order as those of [1,5] sigmatropy of cyclopentadienes. The activation volume of [3,3] sigmatropy of more sterically-hindered substrate was more negative than that of the unhindered one.
  • Keiko Kushioka, Iwao Tanimoto, Kazuhiro Maruyama
    1989 Volume 62 Issue 4 Pages 1147-1153
    Published: 1989
    Released: June 27, 2006
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    2,4-Di-t-butylphenol (1) was efficiently oxidized with H2O2 in methanol in the presence of bis(ethylenediamine)copper(II) (Cu(II)(en)2) complexes. Activity of the Cu(II) complexes was strongly dependent on the structure of the en ligands, as in the cases of the O2 oxidation of phenol 1. In the H2O2 oxidation of 1, ens having none of N-alkyl substituent were of the most efficient. By addition of H2O2, stable Cu(II)(en)2 complexes exhibited a new absorption at 340 nm, which was assigned to Cu(II)–en–H2O2 (1:2:1) complexes. Furthermore, the rapid-scanning spectrophotometry proved that quadruple Cu(II)–en–phenol 1–H2O2 (1:1:1:1) complexes were the key intermediate for the oxidation of 1. The initial velocity can be summarized in the equation v=k[H2O2]1[phenol 1]1[Cu(II)(en)2]1. The oxidation mechanism of phenol 1 with H2O2 is proposed.
  • Masato Kodaka, Toshio Fukaya
    1989 Volume 62 Issue 4 Pages 1154-1157
    Published: 1989
    Released: June 27, 2006
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    The rotational strength of α-cyclodextrin (α-CDx) complex with heptylviologen (1,1′-diheptyl-4,4′-bipyridinium dibromide) was calculated by using the Kirkwood–Tinoco expression. The calculation shows that electric transition polarized along the long axis of heptylviologen gives negative induced circular dichroism (ICD) whereas the short-axis polarized transition gives positive ICD, when HV is axially included in α-CDx and the electric transition moment is located out of the cavity of α-CDx (above the narrower rim). From the comparison between the experimental and calculated results, it is concluded that the heptyl chain of heptylviologen is involved in the cavity while the pyridinium part is situated out of the cavity.
  • Kimio Shindo, Sumio Ishikawa, Tetsuo Nozoe
    1989 Volume 62 Issue 4 Pages 1158-1166
    Published: 1989
    Released: June 27, 2006
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    2-Chloro- or 2-methoxytropone reacts with o-phenylenediamine to give 2-(o-aminoanilino)tropone, which upon heating provides 6H-cyclohepta[b]quinoxaline (10a). Upon acidification, 10a reversibly gives a green cation, 9a. 10a is easily converted, especially under basic conditions, into the oxidative dimer 16a, which reproduces 9a by reduction with Zn in acetic acid. The isopropyl derivatives of these compounds are prepared by the same method from 5-isopropyl-2-methoxytropone. The 5-methyl (21a) and 5,11-dimethyl derivatives 23 are made by the reaction of 2-chloro- or 2-methoxytropone with N-methyl- and N,N′-dimethyl-o-phenylenediamines. However, the methylation of 21a with methyl fluorosulfate affords 5,11-dihydro-8,11-dimethyl-6H-cyclohepta[b]quinoxaline-5,6-sultone. H2O2 oxidation of 10a mainly gives 16a in addition to a small quantity of 6H-cyclohepta[b]quinoxalin-6-one. Compound 21a is stable under basic conditions, but 23 rearranges under alkaline conditions to give, among other unidentified products, N-methyl-N-[o-(methylamino)phenyl]benzamide and 5,10-dihydro-5,10-dimethyl-2-phenazinecarbaldehyde. Reactions of title compounds with alkali and hydrogen peroxide are compared with those of O- and S-analogues.
  • Susumu Tsushima, Yasuhiro Yamada, Tetsuo Onami, Koichiro Oshima, Micha ...
    1989 Volume 62 Issue 4 Pages 1167-1178
    Published: 1989
    Released: June 27, 2006
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    The chiral compounds (R)- and (S)-N-(p-tolylsulfonyl)benzenesulfonimidamide have been prepared efficiently from N-(p-tolylsulfonyl)benzenesulfonimidoyl chloride and both enantiomers were transformed into chiral selenium diimide reagents, (S)- and (R)-N,N′-bis[N-(p-tolylsulfonyl)benzenesulfonimidoyl]selenium diimide, respectively, for the asymmetric allylic amination of olefins. Asymmetric allylic amination of methylenecyclohexane with the S-configured selenium diimide reagent afforded allylic amide, (1S)-N-[(R)-N-(p-tolylsulfonyl)benzenesulfonimidoyl]-2-methylenecyclohexylamine as a major diastereomer (42% diastereomeric excess). Similarly, cyclohexene, 1-heptene, and cyclooctene gave chiral allylic amides with 34%, 32%, and 20% diastereomeric excess, respectively. It is apparent that the S-configured diimido selenium reagent gives S-configured allylic amides, and that the R-configured reagent affords R-configured allylic amides as the major diastereomers in all of the cases investigated.
  • Kaoru Nakamura, Takehiko Miyai, Ashish Nagar, Shinzaburo Oka, Atsuyosh ...
    1989 Volume 62 Issue 4 Pages 1179-1187
    Published: 1989
    Released: June 27, 2006
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    Bakers’ yeast reduces esters of 2-alkyl-3-oxobutanoic acid (CH3COCHRCO2R′; R=methyl, ethyl, propyl, propargyl, and allyl) into the corresponding (S)-hydroxy esters with exclusive stereoselectivity, while the configuration at the 2-position of the hydroxy esters is either S (anti) or R (syn) depending on the structure of the alkoxyl group in the carboalkoxyl moiety of the ester. Oftenly, the stereoselectivity with respect to the 2-position is not satisfactory. In general, the reduction of t-butyl esters exerts predominancy in the products, whereas that of 1,1-dimethylpropyl esters exerts the syn predominancy. A marked difference between these two esters in diastereoselectivity is discussed from the view point of plausible conformations of the esters.
  • Juro Ojima, Masayuki Masumoto, Jyunji Katsuyama, Keiko Kitamura, Masah ...
    1989 Volume 62 Issue 4 Pages 1188-1192
    Published: 1989
    Released: June 27, 2006
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    Dimethylbisdehydrotridecafulvene derivatives bearing various substituents at the exocyclic bond have been synthesized and the inductive effect of substituents upon the tropicity of the thirteen-membered ring is discussed on the basis of the spectral data.
  • Junji Tanaka, Hiroshi Kobayashi, Shuji Kanemasa, Otohiko Tsuge
    1989 Volume 62 Issue 4 Pages 1193-1197
    Published: 1989
    Released: June 27, 2006
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    1-Silylvinyl ketones undergo smooth Michael addition with Grignard reagents generating magnesium enolates which are then trapped with benzaldehyde to give E- and Z-isomers of enones after Peterson condensation. (E)-Olefins become major products under a thermodynamic control when the condensation with benzaldehyde is carried out at room temperature in diethyl ether, while Z-isomers are more favored as kinetically controlled products at −78 °C in THF. Reaction mechanism is briefly discussed.
  • Eiji Wada, Shuji Kanemasa, Otohiko Tsuge
    1989 Volume 62 Issue 4 Pages 1198-1204
    Published: 1989
    Released: June 27, 2006
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    Through hetero Diels–Alder reaction with a vinyl ether and Horner–Emmons olefination, diethyl 2-oxo-3-butenylphosphonate leads to 2-ethoxy-6-(1-alkenyl)-3,4-dihydro-2H-pyrans which are further transformed into 2-chromanones via regioselective Diels–Alder reactions with activated acetylenes followed by hydrolysis and oxidation.
  • Takehiko Goto, Michio Konno, Minoru Saito, Ryu Sato
    1989 Volume 62 Issue 4 Pages 1205-1210
    Published: 1989
    Released: June 27, 2006
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    6-Substituted and unsubstituted 6,7-dihydro-7-hydroxy-5H-pyrrolo[3,4-b]pyridin-5-ones were predominantly obtained in excellent yield by the reduction of the corresponding 5,7-diones with sodium borohydride in the presence of Mg ion at 0 °C. The highly regioselective production of the 7-hydroxy lactam in preference to the 5-hydroxy isomer was reasonably interpreted in terms of a chelate complex formation between the dione and Mg ion. The regioisomeric assignment was achieved by the transformation of the 7-hydroxy lactam to 2-(hydroxymethyl)-3-pyridinecarboxamides which could be converted to the known azaphthalide, furo[3,4-b]pyridin-5(7H)-one. Furthermore, the high chemoselectivity was found to be retained below 0 °C to give the partial reduction product, hydroxy lactam, exclusively.
  • Yasuhiro Tanoue, Akira Terada, Kazuhiko Torisu, Hiroshige Taniguchi
    1989 Volume 62 Issue 4 Pages 1211-1214
    Published: 1989
    Released: June 27, 2006
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    As new intermediates for the syntheses of monosubstituted naphthazarins and anthracyclines, several tetramethoxynaphthalenes having a substituent such as CH3, COOH, CN, Br, OAc, OH, and OMe groups were prepared from 1,4,5,8-tetramethoxynaphthalene and 2-formyl-1,4,5,8-tetramethoxynaphthalene.
  • Hidenori Chikashita, Shun-ichiro Komazawa, Nishiki Ishimoto, Koji Inou ...
    1989 Volume 62 Issue 4 Pages 1215-1225
    Published: 1989
    Released: June 27, 2006
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    A simple and useful new type of protection method for carbonyl groups by conversion into 3-methylbenzothiazoline derivatives with o-(methylamino)benzenethiol was described. With this method, 3-methylbenzothiazolines were conveniently obtained in excellent yields from various aldehydes and ketones. This method allows efficient protection and deprotection under mild and neutral conditions and affords protection of the carbonyl group against both basic and acidic conditions. The difference in reactivity between different carbonyl groups was successfully utilized for the chemoselective benzothiazolination of the formyl group of 4-oxopentanal and also for the chemoselective conversion of 4-androstene-3,17-dione and progesteron into the corresponding benzothiazolines with the nonconjugated keto groups remaining intact. 2-Substituted benzothiazolines derived from aldehydes were efficiently converted into 2,2-disubstituted benzothiazolines via alkylation, with a variety of Grignard or organolithium reagents, of 2-substituted 3-methylbenzothiazolium salts which were readily obtained by the treatment of the former thiazolines with trityl perchlorate in acetonitrile. These salts were also obtained in good yields from aldehydes in one-pot syntheses by the treatment with o-(methylamino)benzenethiol in acetonitrile followed by addition of trityl perchlorate. 3-Methylbenzothiazolium iodide was found to be also effective as a formyl cation equivalent and the reactions with Grignard or organolithium reagents produced the corresponding 2-substituted benzothiazolines in good yields. With this reaction, 2-deuterio-3-methylbenzothiazolium iodide was effectively applied as a deuterated formyl cation equivalent for the synthesis of aldehyde-d.
  • Shigeaki Kasaoka, Eiji Sasaoka, Hideto Iwasaki
    1989 Volume 62 Issue 4 Pages 1226-1232
    Published: 1989
    Released: June 27, 2006
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    In order to develop highly functional catalysts for a dry-type, simultaneous removal of sulfur oxides (SOx) and nitrogen oxides (NOx) the catalytic activities of V2Ox/TiO2, V2Ox/TiO2/AC(activated carbon) and V2Ox/AC (4<x<5) were studied using a fixed bed flow reactor. In this process SO2 is catalytically oxidized to SO3 and then fixed on the catalyst as ammonium sulfates by reactions with H2O and NH3; NOx are reduced to N2 with NH3 over the same catalyst at low temperature (ca. 130 °C). The sulfates deposited on the catalyst must be periodically removed for regeneration in order to realize repeated use of the catalyst. V2Ox/TiO2 was found to be a suitable catalyst for the simultaneous removal and to have an acceptable tolerance for reiterative regeneration. Also, water washing of the used catalyst after a NH3 pretreatment was found to be preferable for regeneration. The sulfates deposited on the catalyst could be recovered as (NH4)2SO4 by this type regeneration. The deposited sulfates were amorphous and could be regarded as being a mixture of NH4HSO4 and (NH4)2SO4. These sulfates reacted with NOx to produce N2.
  • Toshio Takayama, Isao Ando, Tetsuo Asakura
    1989 Volume 62 Issue 4 Pages 1233-1236
    Published: April 15, 1989
    Released: June 27, 2006
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    The dielectric solvent effect on the 29Si NMR chemical shifts of some chlorosilanes is calculated by means of the finite perturbation theory within the CNDO/2 framework using the solvaton theory which is employed to estimate specific solute-solvent bonded interactions as a function of the dielectric constant of the medium. The calculated variations are reasonably compared with the gross trend of the observed solvent effects of 29Si chemical shifts. Further, the origin of the dielectric solvent effect is discussed.
  • Jalal Mohammed Saleh, Yousif Kadim Al-Haidari
    1989 Volume 62 Issue 4 Pages 1237-1245
    Published: April 15, 1989
    Released: June 27, 2006
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    The corrosion behavior of stainless steel (405) specimen in 5 M H2SO4 solution has been investigated potentiostatically at four temperatures in the range 303–323 K. The inhibiting effects of ethanethiol (EtSH), dimethyl sulfide (Me2S), and dimethyl disulfide (Me2S2) have thereafter been tested for four inhibitor concentrations of 0.5, 1, 5, and 10 mmol dm−3. The sulfur compound addition to the H2SO4 solution caused a shift, mainly in the cathodic direction, of the corrosion potential, the electrode potential at low current densities as well as of the linear section of the cathodic Tafel line. The protection efficiency of each sulfur compound was determined at various temperatures and inhibitor concentrations. The sulfur compound acted as a corrosion inhibitor in the H2SO4 solution through adsorption on the stainless steel surface. The kinetic results, operating through a compensation effect, could well account for the variation of the inhibiting capacities of the various sulfur compounds. The results indicated that inhibition process involved the shift of the stainless steel corrosion to those surface sites which are associated with progressively higher energy of activation. EtSH was the most efficient of the three sulfur compounds for inhibiting the corrosion of the stainless steel in H2SO4 solution.
  • Debasis Dasgupta, Susanta Das, Dilip K. Hazra
    1989 Volume 62 Issue 4 Pages 1246-1249
    Published: April 15, 1989
    Released: June 27, 2006
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    The relative viscosities of solutions of tetraalkylammonium bromides, R4NBr, (R=C2H5 to C7H15) have been measured in 2-methoxyethanol (ME) at 25 °C. The data have been analyzed in the form of associated electrolytes and the B-coefficients have been evaluated. The ionic B-values have been determined using the “reference electrolytes” viz. Bu4NBBu4 and Bu4NBPh4. The results have been discussed on the basis of Einstein’s equation and in terms of a transition state treatment.
  • Ivan Gutman, Sven J. Cyvin
    1989 Volume 62 Issue 4 Pages 1250-1252
    Published: April 15, 1989
    Released: June 27, 2006
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    A method for the calculation of the sextet polynomial of unbranched catacondensed benzenoid molecules is proposed. It requires the multiplication of a small number of 2×2 matrices and is therefore very simple.
  • M.S.K. Niazi
    1989 Volume 62 Issue 4 Pages 1253-1257
    Published: April 15, 1989
    Released: June 27, 2006
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    The thermodynamic dissociation constants and the limiting molar conductivities of 2-, 3-, 4-nitrobenzoic and benzoic acids have been determined in water–methanol mixtures at 298 K. The experimental data are analyzed with the Lee and Wheaton conductance equation incorporating modifications. The derived results are compared with the ones in literature, pertaining to analogous media. The findings are interpreted in terms of solute–solvent interactions, intramolecular hydrogen bonding, resonance and inductive effect and the substituent position. The study showed that the dissociation order decreases as 2-nitrobenzoic acid> 3-nitrobenzoic acid≈ 4-nitro benzoic acid> benzoic acid.
  • M. L. Srivastava, Bali Ram
    1989 Volume 62 Issue 4 Pages 1258-1261
    Published: April 15, 1989
    Released: June 27, 2006
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    Studies on hydrodynamic and electroosmotic permeation of water and aqueous solutions of NaCl, KCl, and MgCl2 across progesterone plug membrane have been carried out to characterize the electrical nature of progesterone interfaces. Electrophoretic mobilities of progesterone particles dispersed in these aqueous solutions have also been measured. Experiments were confined to the range where linear flux/force relationships hold. Membrane parameters have been evaluated with the data obtained and the membrane/solution electrical interface has been explained using electrical double layer model and theory of nonequilibrium thermodynamics. Zeta potentials have been evaluated from electroosmotic and electrophoretic flux data and their dependence on concentration examined.
  • Giuseppe Buemi
    1989 Volume 62 Issue 4 Pages 1262-1268
    Published: April 15, 1989
    Released: June 27, 2006
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    AM1 and MNDO methods have been used for optimizing the molecular geometry of all the possible conformations of thieno[3,4-b]thiophene-2-carboxylic acid (1), of its methyl ester (2) and of acetic thieno[3,4-b]thiophene-2-carboxylic anhydride (3). Both methods give comparable results for the thieno[3,4-b]thiophene framework but rather different bond angles for the substituent group of 3. In any case, an equilibrium between two (1,2) or more (3) conformations is conceivable. Although the most stable conformations are predicted to be planar, the rotation of the substituent group implies only low energy increase (rotation barriers are calculated to be about 2 kcal mol−1) which allows wide oscillations. The π→π* electronic transitions do not differ appreciably from those of the parent thieno[3,4-b]thiophene molecule and are better accounted for by the conformations having remarkable rotation around the C7–C9 bond.
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