Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 66 , Issue 3
Showing 1-50 articles out of 56 articles from the selected issue
  • Kazuko Mizuno, Sohichiro Sirato, Kenji Inoue, Yasushi Ogura, Kimio Isa ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 677-681
    Published: 1993
    Released: August 05, 2006
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    CD, UV, and FT-IR measurements were carried out on methanol solutions of N-dodecanoyl-L-glutamic acid and of N-dodecanoyl-L-valine over a concentration range of 5 × 10−3—1 × 10−1 M. A large positive CD band at 212 nm and a small negative one at 240 nm were observed. The positive CD decreased along with a simultaneous increase in the negative CD upon heating. Weak absorption due to a carboxylic carbonyl was found in the wavelength region where the CD bands were observed. The IR measurements reveal that carboxylic acid dimers are formed predominantly over the concentration range studied, and that an amide group does not take part in the formation of a hydrogen bond.
    The two CD bands are explained in terms of the presence of two rotational conformers about the C1–C2 bond of the carboxylic group. This conclusion differs from the assignment of the positive CD band previously reported, which was ascribed to hydrogen bonding between the C*–COOH carbonyl and NH groups.
  • Sadakatsu Nishikawa, Kenichi Matsumura, Masayuki Ueda
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 682-686
    Published: 1993
    Released: August 05, 2006
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    4-Methoxy-1-butanol was synthesized form 1,4-butanediol through potassium 4-hydroxy-1-butoxide. The ultrasonic absorption coefficients in the frequency range from 9.5 to 220 MHz and the sound velocity at 2.5 and 1.92 MHz were measured in aqueous solutions as a function of the concentration. A single relaxational absorption was observed, the cause of which was attributed to the perturbation of an equlibrium associated with a solute–solvent interaction. The rate and thermodynamic parameters associated with the interacion were determined from the concentration dependence of the relaxation frequency. The results were compared with those for other isomeric alcohol solutions, and the effect of the alcohols on the water structure was considered in relation to the molecular structures of the solutes. It has been found that the position of the ether oxygen in the alcohol molecules gives rise to a considerable change in the solution properties.
  • Yoshio Sugiyama, Yasushi Suzuki, Shuichi Mitamura, Tatsuo Nishiyama
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 687-691
    Published: 1993
    Released: August 05, 2006
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    The second-order optical nonlinearities and transparencies of seventeen 4,4′-disubstituted stilbenes and ten related compounds containing a trifluoromethyl group at the para position, as the electron-withdrawing group, were examined. The introduction of a trifluoromethyl group produces a shorter-wavelength shift of the UV-vis absorption spectra without any decrease in the magnitude of the second-order molecular hyperpolarizability (β), as compared with the corresponding nitro-derivatives. The absorption cutoff (λcutoff) of 4-methoxy-4′-trifluoromethylstilbene (1) was observed at 375 nm, which is by ca. 90 nm shorter than that (463 nm) of p-nitroaniline (p-NA); the β value (12.2 × 10−30 esu) of 1, however, is almost equal to that (12.6 × 10−30 esu) of p-NA. The bromo- or methylthio-substituted stilbenes (12 and 16) with a cyano group on the central double bond show SHG activity. The relative intensities of SHG are 3.0 and 1.5, respectively.
  • Tsunenori Nozawa, Mitsushi Nishimura, Masahiro Hatano, Mitsuo Sato
    1993 Volume 66 Issue 3 Pages 692-697
    Published: 1993
    Released: August 05, 2006
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    High-resolution 13C NMR spectra in solid and solution states were observed for tetraphenylchlorin (TPC), tetraphenylbacteriochlorin (TPBC), and tetraphenylisobacteriochlorin (TPIBC). Chemical-shift assignments of the 13C NMR signals for TPBC were completed by a comparison of the 1H decoupled solution 13C NMR spectra with non-decoupled and solid state ones. The absence of signal number changes by temperature in the solution 13C NMR spectra and their comparison with those of the solid state ones suggested the absence of an NH tautomerism in the chlorin ring for TPC and TPBC, indicating the predominant stability of one tautomer over the other. On the other hand, for TPIBC the presence of temperature-dependent signal number changes in the solution 13C NMR spectra were observed. The rate constants of cross polarization (CP) (TCH) and the 1H spin-lattice relaxation time in the rotating frame (T1ρ H) were determined based on the dependence of the NMR magnitude on the contact time.
  • Kenichi Nakabayashi, Yasuhisa Tahara, Masahide Yasuda, Kensuke Shima, ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 698-702
    Published: 1993
    Released: August 05, 2006
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    The cycloreversion of 1,5-diphenylbicyclo[3.2.0]hept-6-ene (1) to 1,4-diphenyl-1,3-cycloheptadiene (2) has been studied by direct photolysis and radiolysis. The γ-radiolysis of 1 in benzene gave 2 quantitatively up to a stationary state where the ratio of 1 to 2 is 0 : 100. However, no isomerization of 2 to 1 occurred. The triplet state of 2 (λmax = 380—385 nm; τ = 2.7—2.8 μs) was formed by pulse radiolysis of 1 in benzene. It has been found that cycloreversion proceeds by an adiabatic mechanism via the triplet state. On the other hand, the quantum yield for the formation of 2 by the irradiation of 254 nm light to 1 was determined to be 0.64 in hexane. The fluorescence spectra of 1 and 2 also indicated that diabatic cycloreversion occurred. The singlet and triplet energy values of 1, as well as those of 2, were estimated to be 102, 78, 75, and 40 kcal mol−1, respectively. The energy difference between the ground states of 1 and 2 was determined to be 20 kcal mol−1 from DSC measurements.
  • Babul Chandra Paul, Kochi Ismail
    1993 Volume 66 Issue 3 Pages 703-708
    Published: 1993
    Released: August 05, 2006
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    Electrical conductivity of sodium dodecyl sulfate (SDS) in sodium acetate–acetic acid buffer solutions was measured as functions of concentration, temperature and pH. First and second critical micelle concentrations (cmc1 and cmc2) of these solutions were estimated. Plot of cmc1 versus pH passes through a minimum in the pH range 5.2 to 5.6. The decrease in cmc1 with increasing pH is shown to be due to the Na+ counterion and is described quantitatively by an analytical expression which also provides the value of counterion binding constant. The increasing tendency of cmc1 with increase in pH is, on the other hand, caused by the acetate co-ion. The enthalpy and standard free energy changes due to micellization of SDS were estimated. The slope of the specific conductivity versus concentration plot above cmc2 is found to decrease with increasing concentration of sodium acetate which is contrary to the trend reported in sodium chloride solution. This study has revealed the effect of the nature of co-ion on micellization.
  • Danilo D. Lasic
    1993 Volume 66 Issue 3 Pages 709-713
    Published: 1993
    Released: August 05, 2006
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    A qualitative model for the formation of inorganic colloidal particles is presented. The model is based on the symmetry of the complexes in solution and on the symmetry of distribution, i.e., position and orientation of the binding sites of the complexes. These factors determine the final particle shape when particles grow by crystallization, while in the case of additional secondary aggregation, it is controlled also by the factors which determine crystal habit and stability of colloidal particles. In addition, kinetic factors have to be considered also because the systems are normally driven through various phases far from themodynamic equilibrium.
  • Hitoshi Ishida, Taisuke Hamada, Yu-ichi Fujishita, Yuri Saito, Katsuto ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 714-720
    Published: 1993
    Released: August 05, 2006
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    Molecular mechanics (MM) calculations were performed for two chiral ligands, 4,4′-bis[R(or S)-phenylethylamino carbonyl]-2,2′-bipyridine (R(or S)-PhEtbpy) and 4,4′-bis(menthoxycarbonyl)-2,2′-bipyridine (Menbpy) by the MM2PRIME program with several new parameters. These ruthenium complexes have been already found to be efficient catalysts for photochemical and enantioselective electron transfer reactions. The bonded terms in the new parameters were determined by Hopfinger's method with molecular orbital (MO) calculations. The MO calculations were mainly performed with AM1 program, however some torsional parameters were also determined by ab initio MO methods to compare with the results derived by semi-empirical methods. The electrostatic parameters were determined with the AM1 program by using the electrostatic potential (ESP) method. To find the most stable conformation, the contour maps of the strain energy of the chiral ligands were drawn as a function of rotation of the chiral groups, and the favorable conformation obtained was supported by 1H NMR measurement. The structures of these ruthenium complexes were also discussed on the CD spectra of the complexes and the enantioselectivity of the reaction.
  • Ken-ichiro Ota, Baek-un Kim, Hideaki Yoshitake, Nobuyuki Kamiya
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 721-726
    Published: 1993
    Released: August 05, 2006
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    The corrosion of Ni coated with alkali carbonates was measured in a CO2/O2 atmosphere at 873—1173 K. The corrosion of Ni coated with carbonates generally obeyed a parabolic rate law under a 67% CO2–33% O2 atmosphere. The parabolic rate constant decreased with an increase in the temperature with a (Li0.62K0.38)2CO3 coating under a 67% CO2–33% O2 atmosphere. This was explained by the solubility of NiO that was formed on Ni metal during corrosion. Hot corrosion was observed several times with (Li0.62K0.38)2CO3 under low CO2 pressure at 1073 K. This hot corrosion could be explained by the dissolution/reprecipitation mechanism of the NiO scale, due to the solubility gradient in the carbonate film.
  • Yasuo Ito, Victor Sanchez, Rafael Lopez, Luz A. Fucugauchi, Kazuhiro T ...
    1993 Volume 66 Issue 3 Pages 727-732
    Published: 1993
    Released: August 05, 2006
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    Positron lifetime measurements were performed for two different kinds of polymers (low density polyethylene and a polyimide 6FDA-TMPD) during sorption of various vapors (hexane, cyclohexane, benzene, acrylic acid, methyl acrylate, water, and oxygen). The vapor sorption affected the long-lived component (ortho-positronium component) in a systematic way regardless of the kind of the vapor molecules, i.e. for the polyethylene both the lifetime and the intensity of the long-lived component were enhanced, while for the polyimide they were decreased significantly. These different effects are interpreted in terms of different states of sorbed molecules in rubbery (the polyethylene) and in glassy (the polyimide) polymers.
  • Kohshin Takahashi, Kenji Horino, Teruhisa Komura, Kazuhiko Murata
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 733-738
    Published: 1993
    Released: August 05, 2006
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    By mixing Zntpp solid with o-chloranil, the rectification and photovoltaic properties of Al/porphyrin/Au sandwich-type cell are improved (Zntpp: 5, 10, 15, 20-tetraphenylporphyrinatozinc). The improvement may be mainly attributable to an increase in the hole concentration as the majority carrier because of the electron transfer from Zntpp to o-chloranil in the ground state. In addition, by mixing H2tpp solid with o-chloranil, the short circuit photocurrent of the sandwich-type cell increases although the rectification property is hardly improved (H2tpp: 5, 10, 15, 20-tetraphenylporphyrin). The fluorescence intensity, the short circuit photocurrent and its temperature-dependence for various porphyrin solids mixed with o-chloranil are measured in order to clarify the photogeneration mechanism of charge carriers. The results suggest strongly that an exciplex formed between H2tpp and o-chloranil molecules contributes to the photogeneration of charge carriers.
  • Tsuneo Fujii, Kei Murayama, Nobuaki Negishi, Masakazu Anpo, Edmund J. ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 739-747
    Published: 1993
    Released: August 05, 2006
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    The fluorescence spectra of pyrene of four sol systems comprising silicon and aluminum alkoxides (Si : Al = 99.4 : 0.6 ; 93.6 : 6.4; 85.9 : 14.1; and 50 : 50) have been observed during sol-to-gel-to-xerogel transitions under at relatively low concentration, on the order of 10−4 mol dm−3, uncatalyzed, and constant temperature (300 K) conditions. The influence of relative humidity on the relative intensities of pyrene monomer and excimer-like fluorescence in the four xerogel states has also been observed. In three of the four systems studied (all but Si : Al = 99.4 : 0.6), fluorescence spectra revealed that excimer concentration increased with time and reached a maximum near 55 days after which it decreased. From our data, it is apparent that the ratio of the intensity of the excimer-like fluorescence to that of the monomer fluorescence increases with relative humidity.
  • Masaharu Okazaki, Yutaka Tai, Kazumi Toriyama
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 748-754
    Published: 1993
    Released: August 05, 2006
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    The ODESR spectrum and magnetic field dependence on recombination fluorescence were observed for X-ray irradiated pyrene-doped polystyrene at temperatures of 242—348 K. The ODESR intensity as a function of the pyrene concentration, 0.1—8.9 wt%, showed an unusual minimum at about 1.0%. Two phases were separated in the magnetic field dependence of the fluorescence: one was sharp and saturates at fields of over 50 mT, while the other was broad with a dip at around 60—150 mT. The cause of this dip was naturally attributed to the ST−1 level crossing. The sharp magnetic field effect also showed a minimum at around a concentration of 1.0 wt%. These novel findings have been interpreted using a recombination model modified from the previous one for pyrene-doped ethylene–propylene rubber and polyethylene. The essential points of the present model are: (1) although electron hopping within the polystyrene molecule is rapid, electron transfer at the last step of recombination between the polystyrene anion and the pyrene cation proceeds at a moderate rate; (2) the hole-transfer rate in the polymer chain is moderate; (3) electron hopping between the doped pyrene molecules is very much dependent on the concentration; (4) hole hopping between the pyrenes is inhibited.
  • Kazuaki Osako, Katusmi Nakashiro, Yoshio Ono
    1993 Volume 66 Issue 3 Pages 755-759
    Published: 1993
    Released: August 05, 2006
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    Mechanical mixtures of ZnO and H-ZSM-5 show high activities and selectivities for the aromatization of isobutane. The temperature-programmed desorption spectra of ammonia and the infrared spectra of adsorbed pyridene revealed that a solid–solid ion-exchange occurs between ZnO and H-ZSM-5. The presence of Zn cations in the zeolite channels not only enhances the dehydrogenation, but also the C–C bond cleavage of isobutane. A mechanism for the activation of isobutane is proposed.
  • Asim K. Das
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 760-765
    Published: 1993
    Released: August 05, 2006
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    The kinetics of the reaction of uranium(VI) with 8-quinolinol and 8-hydroxy-5-quinolinesulfonate under the conditions of 1 : 1 chelate formation in the pH range 3.6—4.6 at different temperatures (20—30 °C) and ionic strength I = 0.1 mol dm−3 (KNO3) have been studied. A dual path mechanism involving both UO2(aq)2+ and UO2(OH)(aq)+ and the partially deprotonated ligand (LH,LH) is consistent under the experimental conditions. The different rate constants under the condition of equilibrium have been determined. The results conform to kobs/B = k1[H+] + k2Kh;
    where

    Kh = hydrolysis constant of UO2(aq)2+; Ka(1) = first deprotonation constant of the ligand, LH2 (charges are omitted); k1 and k2 are the second order forward rate constants of UO2(aq)2+ and UO2(OH)(aq)+ respectively and Q is the equilibrium constant of the reaction, UO22+ + LH UO2L+ + H+, where LH represents the partially deprotonated form of the ligand, 8-quinolinol and a similar reaction occurs for deprotonated 8-hydroxy-5-quinolinesulfonate (LH). Thermodynamic parameters for each of the steps have been determined. The results have been compared with those of recent findings in the interaction of cerium(IV) and iron(III) with these ligands. UO2(aq)2+ has been argued to react through a dissociative interchange (Id) mechanism and its characteristic water exchange rate has been found as a rough estimate. Similarly for UO2(OH)(aq)+, a dissociative mechanism has been speculated.
  • Tomohiro Suzuki, Kin-ichi Tsunoda, Hiroshi Kawamoto, Hideo Akaiwa
    1993 Volume 66 Issue 3 Pages 766-773
    Published: 1993
    Released: August 05, 2006
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    The separation behavior of CoIII-, NiII-, CuII-, and ZnII-STTAs [4-(2-thienyl)-4-thioxo-1,1,1-trifluoro-2-butanone] and CoII-, NiII-, and CuII-TTAs [4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione] in reversed phase high performance liquid chromatography was investigated when various additives were added to the mobile phase. The adduct formation or the masking effect was observed upon addition of additives. When trioctylphosphine oxide was added to the mobile phase, mutual separation of those metal chelates was especially remarkable due to the adduct formation. Moreover, the decomposition of some metal chelates in the HPLC column was also prevented by the adduct formation. On the other hand, 2,2′-bipyridyl and 1,10-phenanthroline showed the masking effect. Such effects of additives were consistent with their synergistic extraction constants in chelate extraction.
  • Jiban Kumar Nag, Sarnath Chattaraj, Arabinda K. Das
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 774-777
    Published: 1993
    Released: August 05, 2006
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    An indirect atomic absorption spectrometric determination of iodide has been proposed. The method involves the formation of chelate complex, [Cu(bptc)I], where BPTC, Hbptc = 2-benzoyl pyridine thiosemicarbazone, within a wide pH range (4.3—8.5), extraction of the complex into butyl acetate solvent and determination of copper signal by flame AAS and hence indirectly determining iodide. The method gave a linear graph upto 10. 4 μg ml−1 of iodide with a limit of detection (3σ) value of 47 ng ml−1. The proposed method was free of spectral interferences from large number of metal ions, anions, and organics. Hence it was successfully applied to iodide determination in laboratory chemicals and commercial grade salts.
  • Yasuhiro Yamamoto, Kazuko Ehara, Katsuo Takahashi
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 778-783
    Published: 1993
    Released: August 05, 2006
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    Electrochemical reactions of divalent nickel complexes, NiX2(RNC)2 (1) (X = I, Br, Cl; R = 2,6-Me2C6H3 (Xyl), 4-Br-2,6-Me2C6H2, 2,4-t-Bu2-6-MeC6H2, 2,4,6-t-Bu3C6H2) were carried out at Hg and Pt electrodes. Cyclic voltammograms (CVs) of 1 at a Pt electrode showed a quasi-reversible redox wave at ca. −0.50 V, due to two-electron reduction [(1) (1)2−]. The reduction potential of the iodide (1a) or bromide (1f) complex (R = Xyl) shifted to the positive side by ca. 0.3 V in the presence of isocyanide, due to the electrochemical reaction of NiX2(RNC)3 (X = I, Br). The chloride complex (1e) showed a similar potential in the presence or absence of isocyanide; there exists no five-coordinated complex. The CV of 1a at a Hg electrode showed a redox wave at −0.74 V, due to the redox reaction of the unsaturated species, “[Ni(RNC)2HgI2]” (4) formed from the reaction of 1a with Hg, suggesting the CE mechanism. Compound 1a had a redox potential at −0.72 V in the presence of 2,6-xylyl isocyanide, being responsible for [Ni(RNC)4HgI2]2. The bromide complex showed a similar behavior, but the chloride complex underwent a very complicated reaction. The electrochemical mechanism of NiX2(RNC)2 with or without isocyanide is discussed.
  • Noriko Shintani, Junko Kotaki, Kozo Sone, Yutaka Fukuda
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 784-789
    Published: 1993
    Released: August 05, 2006
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    Nine mixed chelates of Ni(II) and Cu(II) with N,N,N′,N″,N″′,N″′-hexamethyltriethylenetetramine (hmtt) and β-diketonate (dike) ligands were prepared and characterized. Except for [Ni(dipm)(hmtt)]ClO4 (dipm = dipivaloylmethanate), all of them were found to be binuclear chelates: (i) [M2(dike)4(hmtt)] (M = Ni, dike = dipm,acac(acetylacetonate), tfac, or hfac(tri- or hexafluoroacetylacetonate); M = Cu, dike = hfac), (ii) [Ni2(NO3)2(dike)2(hmtt)] (dike = dipm, acac), and (iii) [Cu2(acac)2(hmtt)](ClO4)2. Although they are similar to their mononuclear analogues containing N,N,N′,N′-tetramethylethylenediamine (tmen), a number of characteristic differences exist. Though the Ni(II) chelates are only slightly solvatochromic, the Cu(II) chelates are strongly so.
  • Haruyo Maeda, Kan Kanamori, Hitoshi Michibata, Takumi Konno, Ken-ichi ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 790-796
    Published: 1993
    Released: August 05, 2006
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    The coordination geometry of bis(L-cysteinato) vanadate(III) was determined by single-crystal X-ray crystallography. The vanadium(III) center coordinates octahedrally two tridentate L-cysteinate ligands via trans S, cis O, and cis N atoms. Bis(D-penicillaminato) vanadate(III) was characterized so as to adopt a similar trans(S) configuration based on its electronic spectrum. The coordination chemistry of the two complexes in solution was examined on the basis of the ligand-to-metal charge-transfer band. One of the two V(III)–S bonds of each complex is easily cleaved in solution.
  • Tsugikatsu Odashima, Kei Sakakura, Katsunori Kohata, Hajime Ishii
    1993 Volume 66 Issue 3 Pages 797-803
    Published: 1993
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    Three hydrazones, 3-, 4-, and 5-nitro-2-pyridinecarbaldehyde 2-pyridylhydrazones, were synthesized. Their properties and reactivities with metal ions and the extraction and characteristics of the resultant complexes have been investigated and compared with one another. As a result, useful information on the molecular design of highly sensitive hydrazone reagents has been obtained.
  • Junji Noro, Tatsuya Sekine
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 804-809
    Published: 1993
    Released: August 05, 2006
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    The solvent extraction of europium(III) in aqueous 0.1 mol dm−3 sodium chloride or sodium nitrate solutions with 2-thenoyltrifluoroacetone (Htta) into chloroform was measured in the absence and presence of tetraethylammonium, tetrapropylammonium, tetrapentylammonium, or tetradecyldimethylbenzylammonium (base+). The addition of quarternary ammoniums enhanced the extraction, except for tetraethylammonium. This enhancement could be explained in terms of the extraction of the ternary complex, the Eu(tta)4base+, in addition to the Eu(tta)3 complex. The difference in the enhancement of extraction with a different quarternary ammonium at a certain total concentration was much smaller than that expected from the difference in the size. This could be explained in terms that although the extraction of the anionic complex should be better when the size of the base+ is larger, its concentration in the aqueous phase at equilibrium is lower because it is extracted with the other anions in the aqueous phase better than a smaller base+. It was also found that the formation equilibrium of the ternary complex, the Eu(tta)4base+, by association of the neutral complex, Eu(tta)3, with the ion-pair, ttabase+, in the organic phase is essentially not affected by the size of the base+.
  • Mrinal Kanti Das, Pradip Kumar Maiti, Arpita Bhaumik
    1993 Volume 66 Issue 3 Pages 810-813
    Published: 1993
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    Investigations with amine–cyanoborane complexes as new viable reducing agents have shown that the reactivity of amine–cyanoborane complexes is highly dependent on the nature of the component amine and on the solvent used, and that the amine–cyanoborane complexes derived from primary amines are highly efficient and chemoselective reducing agents compared to those derived from secondary and tertiary amines.
  • Ritsuko Ehama, Masaki Tsushima, Tomoaki Yuzuri, Hiroko Suezawa, Kazuhi ...
    1993 Volume 66 Issue 3 Pages 814-818
    Published: 1993
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    The formation constants and the enthalpies of formation of CH/π complexes were determined for a series of ternary chloroform/aromatic π-base/carbon tetrachloride (solvent) systems. The enthalpies showed that the interaction is favored by the electron-releasing substituent on the aromatic ring. Electronegative substituents on the CH donor also strengthen the interaction. The fact renders a support on the hydrogen-bond-like nature of the CH/π interaction.
  • Nobuharu Iwasawa, Satoshi Hayakawa, Masahiro Funahashi, Koichi Isobe, ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 819-827
    Published: 1993
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    Various β-carbonyl radicals are generated oxidatively from cyclopropanol derivatives by the use of manganese(III) 2-pyridinecarboxylate (Mn(pic)3). These β-carbonyl radicals react with electron-rich olefins such as conjugated silyl enol ethers, a ketene thioacetal, a ketene dithioacetal, and a vinyl ether intermolecularly to give crossed-addition products in good yield. Furthermore, the combined use of Mn(pic)3 and tributylhydridotin makes it possible to carry out the 1 : 1 addition reaction of these β-carbonyl radicals with electron-deficient olefins such as acrylonitrile, acrylaldehyde, methyl acrylate, methyl vinyl ketone, and N,N-dimethylacrylamide, and the corresponding products are obtained in moderate to good yield.
  • Yoshihiro Ohba, Keisaku Irie, Fu Sheng Zhang, Tyo Sone
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 828-835
    Published: 1993
    Released: August 05, 2006
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    A series of compounds in which a part or all of the methylene bridges of acyclic p-t-butylphenol–formaldehyde oligomers are replaced by C=O bridge(s) has been synthesized. The carbonyl-bridged tetramers, except for that with no methylene bridge, formed crystalline host–guest complexes with various organic compounds; those with two C=O bridges were superior regarding complexation, regardless of the position of the bridges. Exclusive guest selectivity of the tetramer with one terminal C=O bridge was observed for benzene and its methyl derivatives in a two-component system. The fully carbonyl-bridged dimer, trimer, tetramer, and pentamer had no complexing-capability. The thermal stability of benzene complexes (host : guest = 2 : 1) of the tetramers with one C=O bridge, as estimated from their thermal dissociation rates, are remarkably lower than that of the parent tetramer. Oximes derived from the tetramers with one C=O bridge were much more effective than the corresponding carbonyl-bridged ones regarding their complex-forming capability.
  • Toyoshi Shimada, Ritsuko Kurazono, Kensaku Morihara
    1993 Volume 66 Issue 3 Pages 836-840
    Published: 1993
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    “Footprint catalysts” are silica(alumina) gel catalysts with tailored substrate specificities; they are easily prepared by the present authors' molecular imprinting procedures with an appropriate template. Four footprint catalysts were newly prepared by imprinting using p-acetamido-substituted derivatives of benzenesulfonamide and benzamide as templates. They catalyzed transacylations of benzoic anhydride and 4-(acetamido)benzoic benzoic anhydride, respectively. The effects of the acetamido substituents apart from the reaction center on the substrate specificities were investigated.
  • Junko Ohkanda, Takeshi Tokumitsu, Keiryo Mitsuhashi, Akira Katoh
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 841-847
    Published: 1993
    Released: August 05, 2006
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    The reaction of N-(benzyloxy)urea with 1,1,3,3-tetraethoxypropane, 4,4-dimethoxy-2-butanone, and 2,4-pentanedione under acidic conditions gave the corresponding 1-benzyloxy-2(1H)-pyrimidinones (3 and 3′) in moderate yields. In contrast, the reaction of N-(benzyloxy)urea or N-methoxyurea with 1-phenyl-1,3-butanedione exclusively gave 3-alkoxyimino derivatives (4). 1-Benzyloxy-2(1H)-pyrazinones (9a and 9b) were synthesized via three steps starting from N-(t-butoxycarbonyl)glycine. The hydrogenation or treatment with 30% HBr in acetic acid of compounds 3c, 9a, and 9b afforded 1-hydroxy-4,6-dimethyl-2(1H)-pyrimidinone (HOPY), and 1-hydroxy- (HOPR-H), and 1-hydroxy-5,6-dimethyl-2(1H)-pyrazinone (HOPR-Me), respectively. They form 3 : 1 complexes of iron(III) with the N-hydroxyamide groups in the acidic region, but the stability constants of their iron(III) complexes are far below that of natural ferrioxamine B.
  • Kazuaki Kudo, Yukihiko Hashimoto, Hitoshi Houchigai, Masaki Hasegawa, ...
    1993 Volume 66 Issue 3 Pages 848-856
    Published: 1993
    Released: August 05, 2006
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    α-(Sulfenylmethyl)allyl acetates reacted with silylated carbon nucleophiles in the presence of a catalytic amount of TMSOTf to give products substituted at the α-position of the sulfenylmethyl group in moderate to good yields with high regioselectivity. The theoretical calculation on an intermediate cationic species indicated that an episulfonium ion was a stable form; the observed regioselectivity was rationalized qualitatively on the basis of the coefficients of LUMO of the cation. Some transformations of the products were also demonstrated.
  • Toshiaki Yamashita, Taiji Tsurusako, Nobuya Nakamura, Masahide Yasuda, ...
    1993 Volume 66 Issue 3 Pages 857-862
    Published: 1993
    Released: August 05, 2006
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    The 9,10-Dicyanoanthracene (DCA)- or 9-cyanoanthracene-sensitized photooxygenation of trans-stilbene derivatives gave benzaldehyde derivatives efficiently in the presence of weak-nucleophilic salts, such as Et4NOAc and KOAc/18-crown-6 ether. The product distribution of this photooxygenation was apparently different from that of each photooxygenation in the presence of Mg(ClO4)2 and Et4NBF4 or in the absence of the salt. The DCA-sensitized photooxygenation of 2-methylnaphthalene gave phthalic acid and 4-methylphthalic acid in the presence of Et4NOAc. These products were different from the products generated from each photooxygenation in the presence of Et4NBF4 and KClO4 or in the absence of the salt. Also, such ring-oxygenation occurred in the DCA-sensitized photooxygenation of 2,3-dimethylnaphthalene and naphthalene in the presence of Et4NOAc. These photooxygenations in the presence of Et4NOAc proceeded by the addition of an acetate ion to the cation radical of the substrate generated by a photochemical electron transfer from the substrate to the sensitizer and the subsequent reaction with O2 and the related oxygen species.
  • Tsuneaki Hida, Shigetoshi Tsubotani, Yasunori Funabashi, Hideo Ono, Se ...
    1993 Volume 66 Issue 3 Pages 863-869
    Published: 1993
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    Sperabillins, novel antibiotics, were isolated from the culture filtrate of Pseudomonas fluorescens YK-437. The structure of sperabillin A was elucidated to be 3-[[(3R,5R)-3-amino-6-[(2E,4Z)-2,4-hexadienoylamino]-5-hydroxyhexanoyl]amino]propanamidine dihydrochloride. Sperabillin B has a methyl substituent at the C-6 position of sperabillin A. Sperabillin C and D are (2E,4E)-isomers of the 2,4-hexadienoyl moiety of sperabillin A and B, respectively.
  • Toshihide Hatsui, Shin-ya Ikeda, Hitoshi Takeshita
    1993 Volume 66 Issue 3 Pages 870-876
    Published: 1993
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    A series of proto-photocycloadducts of methyl 2,4-dioxopentanoate to methylenecycloalkanes and -alkenes spontaneously caused retro-benzilic acid rearrangement in high yields. The results are utterly different from those of sterically-crowded acyclic alkenes, with which the rearrangement occurred by thermolysis as a minor process.
  • Tokunaru Horie, Hideaki Tominaga, Isao Yoshida, Yasuhiko Kawamura
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 877-881
    Published: 1993
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    Demethylation of 6-hydroxy-3,5,7-trimethoxyflavones and their acetates was studied and the following results were found. Demethylation of 6-hydroxy-3,4′,5,7-tetramethoxyflavone with 30% anhydrous aluminum chloride in acetonitrile afforded a mixture of 5,6-dihydroxy-3,4′,7-trimethoxyflavone and 5,6,7-trihydroxy-3,4′-dimethoxyflavone, but demethylation of its acetate formed the 5,6,7-trihydroxyflavone as a main product. The latter reaction was applicable as a general method for synthesizing 5,6,7-trihydroxy-3-methoxyflavones. On the other hand, the demethylation of 6-hydroxy-3,4′,5,7-tetramethoxyflavone with 10% anhydrous aluminum bromide in acetonitrile afforded the 5,6,7-trihydroxyflavone as a main product without cleavage of the 4′-methoxyl group and the reaction was more conveniently applicable for the synthesis of the 5,6,7-trihydroxyflavones. The method, however, was not adapted to the synthesis of the flavones with methoxyl groups adjacent to the hydroxyl group on the B ring, since the benzyloxyl group and the methoxyl group adjacent to the hydroxyl group were simultaneously cleaved under demethylating conditions. Seven 5,6,7-trihydroxy-3-methoxyflavones were synthesized by these methods and their properties were clarified.
  • Tsunehiro Harada, Teruaki Mukaiyama
    1993 Volume 66 Issue 3 Pages 882-891
    Published: 1993
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    In the presence of a catalytic amount of trityl hexafluoroantimonate, sequential reactions of epoxides with silylated nucleophiles, rearrangement of epoxides and C–C or C–O bond forming nucleophilic reaction onto the intermediate carbonyl compounds, proceed smoothly to afford the corresponding products in fairly good yields by one-pot procedure. Trityl hexafluoroantimonate (5 mol %) efficiently promotes the above plural sequential reactions.
  • Masafumi Yasunami, Shiro Miyoshi, Noriko Kanegae, Kahei Takase
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 892-899
    Published: 1993
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    Methyl 3-alkylazulene-1-carboxylates were synthesized in high yields by the reaction of 3-methoxycarbonyl-2H-cyclohepta[b]furan-2-one with in situ generated morpholine enamines of aldehydes. Treatment of the esters with 100% phosphoric acid gave 1-alkylazulenes in excellent yields. Azulene was also synthesized in a good yield via methyl azulene-1-carboxylate with a modification of this method.
  • Yutaka Adegawa, Yukihiko Hashimoto, Lan Fang, Masataka Nakamura, Kazus ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 900-905
    Published: 1993
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    (±)-anti Head-to-head umbelliferone dimer was resolved into a pair of optically active forms in good yields with high optical purity by a diastereomeric separation of two diastereomeric diamides obtained by the ring-opening addition reaction with optically pure erythro-2-amino-1,2-diphenylethanol or norephedrine, followed by hydrolysis and relactonization. The absolute configuration of the cyclobutane in (−)589-anti head-to-head umbelliferone dimer was confirmed to be (S,S,S,S) by an X-ray crystallographic analysis of the diamide derived from the (−)589-form by the ring-opening addition reaction with (S)-(−)589-1-(1-naphthyl)ethylamine. The absolute configuration of the cyclobutane in (−)589-anti head-to-head umbelliferone dimer is in agreement with that in (−)589-anti heat-to-head coumarin dimer.
  • Kensaku Morihara, Satoko Kawasaki, Miki Kofuji, Toyoshi Shimada
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 906-913
    Published: 1993
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    Chiral “molecular footprint” catalytic cavities were formed on a silica(alumina) gel surface by molecular imprinting with a chiral template, bis(N-benzyloxycarbonyl-L-alanyl)amine. These cavities exhibited stereoselective catalyses in the transacylation of the corresponding substrates: L-, D-, and meso- forms of bis(benzyloxycarbonyl-alanyl) oxide.
  • Masayuki Hoshi, Yuzuru Masuda, Akira Arase
    1993 Volume 66 Issue 3 Pages 914-919
    Published: 1993
    Released: August 05, 2006
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    The reaction of 1,2-bis(trimethylsilyl)ethyne with a stoichiometric amount of dialkylborane proceeds to the monohydroboration stage, giving [(Z)-1,2-bis(trimethylsilyl)ethenyl]dialkylborane. In situ treatment of the above alkenylborane with iodine in the presence of aqueous sodium hydroxide provides highly pure (E)-1-alkyl-1,2-bis(trimethylsilyl)ethene whose alkyl group migrates from the boron atom. Successive treatment of [(Z)-1,2-bis(trimethylsilyl)ethenyl]dicyclohexylborane with copper(I) iodide, allyl bromide, and aqueous sodium hydroxide affords a cross-coupling product, (Z)-1,2-bis(trimethylsilyl)-1,4-pentadiene, stereoselectively. A similar cross-coupling reaction with 1-bromo-1-hexyne followed by UV irradiation affords (E)-1,2-bis(trimethylsilyl)-1-octen-3-yne stereoselectively.
  • Kiyoshi Mutai, Ryoichi Nakagaki, Hideyuki Tukada
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 920-926
    Published: 1993
    Released: August 05, 2006
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    Photoredox reaction mechanism of a homologous series p-O2NC6H4O(CH2)nNHPh (1) in acetonitrile and benzene is studied. The major products are p-ONC6H4O(CH2)n−1CHO (3) and aniline derived from intramolecular reaction, but the presence of minor amounts of intermolecular reaction products, p-O2NC6H4O(CH2)n−1CHO (4) and p-ONC6H4O(CH2)nNHPh (5) is confirmed in the reaction mixture. In the presence of an external magnetic field, the yield of 3 is suppressed and those of 4 and 5 are correspondingly increased, while the rates of the disappearance of 1 and of the formation of aniline remain unchanged, suggesting the presencer of biradical recombination process accompanied by intersystem crossing in a rate-determining step. On the basis of these observations, two reaction schemes are proposed. The magnetic field effects provide strong evidence for the presence of a transient species with (nitro)N(OH)–O–CHN< group generally supposed for nitro oxygen transfer process in this type photoreaction.
  • Izuo Aoki, Yohko Kawahara, Toru Sakaki, Takaaki Harada, Seiji Shinkai
    1993 Volume 66 Issue 3 Pages 927-933
    Published: 1993
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    A fluorescent receptor, N,N′-bis[6-[4-(1-pyrenyl)butanamido]-2-pyridyl]isophthalamide (2), was synthesized to develop a sensitive host–guest-type sensory system for barbiturates. 2 aggregates in cyclohexane and the pyrene fluorescence in 2 almost disappeared because of aggregation-induced concentration quenching. The addition of barbital to the cyclohexane solution of 2, which induced the deaggregation of 2 through complementary complexation with barbital, increased the fluorescence intensity at 378 nm by a factor of about 70-fold. The barbiturates in water could also be sensitively detected by 2 based on a liquid (water)–liquid (cyclohexane) extraction technique. In this system, 2 was essentially selective for barbiturates and no fluorescence response was observed for guests including a hydantoin skeleton. The analogue of 2, which has the N,N′-di-(2-pyridyl) terephthalamide skeleton, was also investigated as a fluorescent receptor for dicarboxylic acids.
  • Saburo Nakanishi, Takehiro Hirano, Hiroshi Moriuma, Makoto Shiomi, Yos ...
    1993 Volume 66 Issue 3 Pages 934-940
    Published: 1993
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    The reaction of cyclopentadienyl anions with Fe(CO)5 in the presence of acyl chlorides or carboxylic anhydrides gave cyclic acyliron complexes [η5-C5H4C(OCOR)=C(OCOR)CO]Fe(CO)2 via triple carbonylation of the anions and a double acylation. The structure of [η5-C5H4C(OCOCH2CH3)=C(OCOCH2CH3)CO]Fe(CO)2 thus obtained was confirmed by the X-ray analysis. Diastereomers of indenyl derivative [η5-C9H6C(OCOCH2CH3)=C(OCOCH2CH3)CO]Fe(CO)(P(OCH3)3) were prepared by substitution of CO ligand with trimethyl phosphite and the structure of the diastereomers were characterized by NMR spectroscopy using 2D technique. Treatment of cycloheptatrienyl anion with Fe(CO)5 and acyl chloride resulted in double carbonylation to give [η5-C7H6C(OCOR)=C(OCOR)]Fe(CO)2. The mechanism of the reaction is proposed.
  • Yutaka Adegawa, Lan Fang, Masataka Nakamura, Masaki Hasegawa, Kazuhiko ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 941-947
    Published: 1993
    Released: August 05, 2006
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    Optically active polyamides having 2,4-dihydroxyphenyl groups in the side chain were synthesized by the ring-opening polyaddition reaction of (−)-anti head-to-head umbelliferone dimer with diamines, such as 1,6-hexanediamine, 1,4-phenylenediamine, m-xylene-α,α′-diamine, and piperazine. Chiroptical properties of the polyamides were elucidated on the basis of their circular dichroism (CD) spectra in solution and in the film state. The polyamide having a 1,4-phenylene moiety in the diamine component existed in an ordered conformation even in a neutral DMAc solution. Moreover, the polyamides having 1,4-phenylenediamine or piperazine as a component existed in an ordered conformation in the film state. The steric repulsion and/or hydrogen bonding of the para-hydroxyl group on the phenyl group in the side chain was found to play a significant role to reveal the ordered conformations.
  • Naoki Toshima, Toshihide Asakura
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 948-954
    Published: 1993
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    Various organic thin films were obtained by vacuum deposition of poly(p-phenylene) (PPP) synthesized by three different methods: Grignard coupling of p-dibromobenzene (PPP-Y), and two kinds of oxidative cationic polymerization of benzene (PPP-K by a CuCl2–AlCl3 system and PPP-T by a CuCl–AlCl3–O2 system). The IR absorption band at 760 cm−1, which is attributed to a mono-substituted benzene ring, was stronger for the PPP thin films than that for the original PPP. The deposited thin films were partially soluble in THF and chloroform. The electronic absorption spectra of the PPP-K and the PPP-T thin film solutions had shoulders near 410 nm, while that of the PPP-Y film did not. The emission spectra had a peak at 375 nm for the PPP-K and the PPP-Y solutions. In contrast, the PPP-T solution had emission peaks at 465 and ca. 500 nm in addition to a peak at 380 nm, and the excitation spectrum for the peak at 465 nm was quite different from that for the peak at 380 nm. As for thin films, the PPP-K and the PPP-Y had emission peaks at 400—500 nm, while the PPP-T had an emission peak at 615 nm in addition to the peaks at 400—500 nm. The difference in the emission spectra is discussed in terms of the difference in contaminating by-products in the corresponding PPP.
  • Miyuki Ishimura, Hisashi Uedaira
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 955-956
    Published: 1993
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    The spin-lattice relaxation times (T1) of 31P in α-chymotrypsin phosphate buffer solutions were measured as a function of the buffer concentration. The absorption isotherm of phosphate ions was obtained from the concentration dependence of 1/T1. The value of the equilibrium constant and the number of saturate sites were 66 and 42.
  • Masashi Murata, Naoko Yoshie, Minoru Sakurai, Yoshio Inoue
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 957-959
    Published: 1993
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    A revised MM2 force field is developed for the study of normal mode dynamics of glucopyranose. The revised potential function is found to reproduce the vibrational spectrum and equilibrium structure of D-glucopyranose better than the original parameter set.
  • Seiji Tone, Masashi Kunitake, Motoko Uchida, Toyoki Kunitake, Tisato K ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 960-962
    Published: 1993
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    Molecular assembly of polymerizable amphiphile ([2-(acryloyloxy)ethyl][10-[N-[1,3-bis(hexadecyloxycarbonyl)propyl]carbanoyl]decyl]dimethylammonium bromide, designated as dihexadecyl N-[11-[[2-(acryloyloxy)ethyl]dimethylammonio]undecanoyl]glutamate bromide, 2C16L-Glu–C11N+Ac) in the LB film was investigated in the temperature range above and below of the crystal–liquid crystal phase transition on the basis of wide-angle X-ray diffraction measurements. The crystal–liquid crystal phase transition temperature, Tc was determined to be 323 k based on differential scanning calorimetry (DSC). The LB film was in the form of highly oriented bilayer lamella and hexagonally assembled cylinder (rod) structure below and above Tc of the LB film, respectively. The hexagonally assembled cylinder structure above Tc may be formed due to the reason why a hydrophobic part occupies much larger cross-sectional area in comparison with that of a hydrophilic part above Tc. The change of bilayer lamella-hexagonally assembled cylinder was thermally reversible beyond Tc.
  • Hiroshi Saito
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 963-965
    Published: 1993
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    SERS intensity of pyridine has been examined as a function of the amount of charge necessary for the formation of Ag atom during the ORC procedure in each of several electrolytes. The amount of the reduction charge was controlled so as to hold a constant value of around 50 mC cm−2. Although the efficiency of charge recovery in the reduction process with nonhalide ion was very poor compared with chloride ion, intense SERS bands as large as in the case of chloride ion were found even in the case of nonhalide ion.
  • Edison Munaf, Wenzhi Hu, Hiroki Haraguchi
    1993 Volume 66 Issue 3 Pages 966-968
    Published: 1993
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    Flow injection analysis with spectrophotometric detection has been developed for the determination of phosphorus in biological samples. Potassium peroxodisulfate was used as an oxidizing reagent with aid of a platinum wire as the catalyst, and organophosphorous compounds were converted to orthophosphate which reacted with ammonium molybdate in the presence of ascorbic acid to form the molybdenum blue complex. The absorbance of the complex was detected at 880 nm.
  • Keiji Miyazaki, Yoshimasa Ogawara, Takako Kimura
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 969-971
    Published: 1993
    Released: August 05, 2006
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    Calibration of moisture in HCl in the sub-ppm range was performed by gas-phase FTIR spectroscopy, giving a linear correlation between infrared absorbance and the moisture concentration. Minimum detectability was estimated to be 30 ppb with 5-min scan time at 2 cm−1 spectral resolution at 1.6 kg cm−2 pressure, using an InSb detector and an 8-m-pathlength gas cell.
  • Shin-Geol Kang, Soo-Kyung Jung, Mi-Seon Kim, Jong-Hwan Park, Soo-Dong ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 3 Pages 972-974
    Published: 1993
    Released: August 05, 2006
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    The equilibrium constants (K) for the reaction [Cu(A)]2+ + X [Cu(A)X]+ (A = 1,3,6,9,12-pentaazabicyclo[10.2.1] pentadecane; X = Br or Cl) in acetonitrile, DMF, and DMSO have been determined at 25 °C. The large K values (>8.8 × 104) and other results show that the copper(II) complex can be used as a probe for kinetic study of the Menschutkin reaction even in the basic solvents.
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