Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 68 , Issue 12
Showing 1-47 articles out of 47 articles from the selected issue
  • Eiji Yashima, Yoshio Okamoto
    1995 Volume 68 Issue 12 Pages 3289-3307
    Published: 1995
    Released: July 10, 2006
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    Chromatographic enantioseparations, particularly resolution by high-performance liquid chromatography (HPLC), have advanced considerably in the past decade, and have become a practically useful method not only for determining their optical purity, but also for obtaining optical isomers. The preparation of a chiral stationary phase (CSP) capable of effective chiral recognition is the key to this separation technique. We have found that polysaccharide derivatives, particularly cellulose esters and phenylcarbamate derivatives of cellulose and amylose, are very effective CSPs, and can resolve a wide range of racemates, including drugs. A variety of polysaccharides derivatives involving tribenzoates and tris(phenylcarbamates) of cellulose and amylose were prepared and their chiral recognition abilities were evaluated as CSPs in HPLC. The chiral recognition and resolving ability of the derivatives depend greatly on the substituents introduced on the phenyl moieties. The introduction of electron-donating or electron-withdrawing substituents improved the chiral recognition ability. Among the many derivatives of polysaccharides, 3,5-dimethylphenylcarbamates of cellulose and amylose and cellulose tris(4-methylbenzoate) show high chiral recognition, which has allowed the resolution of more than 80% of the racemates tested. These CSPs can be used for both analytical and preparative separations of enantiomers. Some significant mechanistic aspects are also briefly reviewed.
  • Kiyokazu Fuke, Ryozo Takasu
    1995 Volume 68 Issue 12 Pages 3309-3318
    Published: 1995
    Released: July 10, 2006
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    The photochemical reaction of ammonia clusters in the first excited state was studied by a femtosecond pump-probe technique and time-of-flight mass spectroscopy. Small ammonia clusters containing the NH4 radical were probed by a resonance enhanced two-photon ionization method. The NH4 radical is formed within 0.5 ps, and decomposes with a lifetime of 13 ps. The ammonia dimer ion was found to be formed mainly through the one-photon ionization of a new photolysis product such as an excited-state NH4*–NH2. This intermediate may correspond to a cage product in the predissociation process of larger ammonia clusters; its formation and decay times are ca. 1 ps and > 1 ns, respectively. We also examined the lifetimes of NH4(NH3)n using the pump-probe technique with nanosecond lasers. The lifetime of NH4 was found to be elongated by more than 106 times in ammonia clusters. The mechanism of the formation and decay processes for these species as well as for the resonance-enhanced two-photon ionization of ammonia clusters were discussed on the basis of the present results in conjunction with theoretical results from literature.
  • Yasuko Takahashi, Hatsumi Watanabe
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3319-3324
    Published: 1995
    Released: July 10, 2006
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    The interaction of colloidal chitin [a polysaccharide consisting of β-(1-4)-linked N-acetyl-D-glucosamine (GlcNAc) residues] and chlorophyll a (chl.a) in ethanol–water mixed solutions was investigated by means of vis and UV absorption spectroscopy. The observed facts and discussions are as follows: (i) In ethanol (10%)–water mixed solutions, the reaction rate for complex formation between colloidal chitin and chl.a shows an oscillatory dependence on their concentration ratio. At specific ratios of 7.4 × 1, 2, 4, 8··· of sugar units of chitin to one chl.a molecule, a host–guest complex of colloidal chitin with chl.a is produced. (ii) Another oscillatory phenomenon on the spectral bands of chl.a in the solution is also found as a function of the ethanol concentration. This phenomenon is discussed in terms of cluster formation of ethanol and water molecules in binary mixed solvents. (iii) Upon increasing the ethanol concentration, the host–guest complex of colloidal chitin with chl.a begins to collapse when the ethanol concentration in the solution exceeds a critical value up to which the hydrophilic/hydrophobic hydration equilibrium of the system is attained.
  • Irona Nongkynrih, Mahendra K. Mahanti
    1995 Volume 68 Issue 12 Pages 3325-3329
    Published: 1995
    Released: July 10, 2006
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    Kinetic data on the rates of quinolinium dichromate oxidation of some bicyclic alcohols are reported and discussed with reference to the factors that influence the nature of the transition state. The mechanistic pathway has been visualized via the formation of the intermediate chromic ester which undergoes decomposition to give the product. A cyclic transition state is suggested; being a Hückel-type system (4n + 2), this would be an allowed process.
  • Ashim K. Dutta, Gautam B. Talapatra, Tridibendra N. Misra
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3331-3335
    Published: 1995
    Released: July 10, 2006
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    The exciton transport in the presence of both orientational and substitutional disorders is investigated at 77 K. The systems of study include different compositions of 1,4-dibromonaphthalene (DBN) and 1-bromo-4-chloronaphthalene (BCN). In DBN, crystal phosphorescence emission is in conformity with quasi-one-dimensional exciton motion. Fluorescence emission from an impurity and phosphorescence emissions from the triplet state of DBN and from an impurity site present in the DBN crystal have been observed. However the fluorescence emission from the first excited singlet state of DBN is absent. In BCN-doped DBN crystal, the emission corresponding to first triplet of DBN disappears. With the increase of BCN concentration, fluorescence intensity of impurity S1IMP decreases, while the impurity phosphorescence emission intensity increases. The role of the deep trap present in DBN and the effect of orientational disorder due to BCN on the energy transfer processes have been discussed. The experimental results are explained quite satisfactorily in terms of the percolation model, which suggests a two-dimensional exciton transport topology in the mixed crystal.
  • Masatoshi Hirayama, Toshitaka Terasaka, Yoshiro Yamashita, Takanori Su ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3337-3339
    Published: 1995
    Released: July 10, 2006
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    ESR study of the anion radical produced by the reduction of the title compound (DTB-BDTD) with potassium metal in 1,2-dimethoxyethane is reported. In addition to the satellites of 17O, 13C, and 33S, the second-generation satellite lines of extremely low intensity, arising from both 13C and 33S isotopes in natural abundance, have been detected. It was found that these satellites vary markedly in line width among each component of its multiplet. This line width effect was used to determine the sign of hfs constants of these magnetic nuclei, and the resulting signs agreed well with those estimated from the spin densities obtained by the McLachlan procedure and the INDO method.
  • Kazunaka Endo, Kyonosuke Yamamoto, Hiroaki Okada
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3341-3345
    Published: 1995
    Released: July 10, 2006
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    A sum-over-states third-order perturbation theory using a semiempirical wavefunction parameteric method 3 was applied to 29Si and 13C nuclear magnetic shielding constants of SiX4 and CH4−nXn (X = Cl, Br, I; n = 1, 2, 3, 4), respectively. The other new spin-orbit (LS) term, σLS(A), was proposed to come from the cross term involving the halogen spin-orbit coupling, Fermi I·S interaction and the external field-(carbon or silicon) orbit interaction. The values using the MO method predicted a substantial contribution (25%) of σLS(Si or C) to the σLS(X) as already given. The results agreed fairly well with the experimental values, indicating the importance of the spin-orbit effect on the chemical shifts of molecules containing halogen heavier atoms. The dominant contribution of electronic states to the LS shifts is due to the excitations from all occupied MOs to only all vacant σ*Si(or C)–X antibonding MOs, since the Fermi interaction intervenes between the shift contributions.
  • Kyoko Ito, Kayako Hori
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3347-3354
    Published: 1995
    Released: July 10, 2006
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    Single crystal X-ray analysis has been carried out for the title compounds with different chiral groups, which result in different phase sequences: crystal (cryst.)-smectic G(SG)-SJ*-SF*-SI*-SC*-SA-cholesteric (chol.)-isotropic (iso.) for the 2-methylbutyl compound (1) and cryst.-SB-SA-iso. for the 1-methylheptyloxy compound (2). Each crystal has a smectic-like layer structure, in which the molecular tilt angle is 25° in 1 and 15° in 2. Biphenyl moieties are almost coplanar and normal chains have all-trans conformations in both crystals. However, long chains of the chiral groups of 2 have twisted conformations and are arranged between layers. Relationships between the crystal structures and the mesophase behavior are discussed in terms of conjugation of the polar groups and overlapping of biphenyl moieties for the related compounds.
  • Atsushi Yokoyama, Keiichi Yokoyama, Ginji Fujisawa
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3355-3363
    Published: 1995
    Released: July 10, 2006
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    The mechanism of the infrared multiphoton dissociation of the title molecule has been studied using photofragmentation translational spectroscopy. The HCl elimination and the C–Cl bond rupture occurred competitively as primary dissociation channels. The HCl elimination reaction accounts for % of the total primary dissociation yields at 16 ± 3 J cm−2. This is consistent with the branching ratio calculated by RRKM theory. A C=C bond rupture of the CF2CFCl molecules and C–Cl bond rupture of C2HF3Cl radicals were also observed as secondary photodissociation processes. The average excitation energy of the dissociating 1,2-dichlorotrifluoroethane molecules was found to be 14—36 kcal mol−1 (1 kcal mol−1 = 4.184 kJ mol−1) above the C–Cl dissociation threshold of the molecules by comparing the observed center-of-mass translational energy distribution for the C–Cl bond rupture with that calculated by Rice–Ramsperger–Kassel–Marcus (RRKM) theory.
  • Taira Imamura, Akira Kishimoto, Takashi Sumiyoshi, Kenta Takahashi, Ta ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3365-3371
    Published: 1995
    Released: July 10, 2006
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    Pulse radiolysis of a ruthenium(III,III) oxo-acetato dinuclear complex, [Ru2(μ-O)(μ-CH3COO)2(pyridine)6](PF6)2 (abbr. Ru2(33)), in acetonitrile was studied. Electron-pulse irradiation of deaerated acetonitrile solutions caused one-electron reduction of Ru2(33) to form Ru2(32) by the acetonitrile radical anion, CH3CN•−, with a rate constant of 8.0 × 1010 M−1 s−1 (M−1 = dm3 mol−1) at 17 °C. In the solutions containing O2, Ru2(33) was competitively reduced by CH3CN•− and the superoxide ion, O2, with a rate constant of 1.1 × 1010 M−1 s−1, to form Ru2(32). This was reoxidized by the peroxyl radical, O2CH2CN, with a rate constant of 7.5 × 109 M−1 s−1 to regenerate the parent complex of Ru2(33). The reaction scheme is discussed in comparison with the results for the ruthenium(III,III,III) trinuclear complex, [Ru3(μ3-O)(μ-CH3COO)6(pyridine)3]PF6 (abbr. Ru3(333)), reported previously.
  • Fulvio Corradini, Andrea Marchetti, Mara Tagliazucchi, Lorenzo Tassi
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3373-3381
    Published: 1995
    Released: July 10, 2006
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    Densities (ρ) at various temperatures ranging from −10 up to +80 °C have been measured for N,N-dimethylformamide + 2-methoxyethanol + 1,2-dimethoxyethane ternary solvent system, employing 66 mixtures covering the whole miscibility field. Polynomial equations describing the dependence on temperature, ρ = ρ(t/°C), and molar composition, ρ = ρ(X1,X2), have been checked. Furthermore, the excess molar volumes (VE), derived from ρ values, can provide useful suggestions about the formation of solvent–cosolvent complexes. Excess molar volumes have been interpreted on the basis of specific interactions between unlike molecules, taking into account geometric effects and steric hindrances. The VE quantities have been isothermally fitted by an empirical relation of the type VE = VE(X1,X2,X3) formally derived from the well known Redlich–Kister equation. As a rule, for all the here tested relationships, the calculated values agree very well with the experimental ones, indicating that all the equations can be safely employed for predictive calculations in correspondence of the experimental data gaps.
  • Akio Katsuki, Kimio Akiyama, Shozo Tero-Kubota
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3383-3389
    Published: 1995
    Released: July 10, 2006
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    Electron spin polarization has been studied in order to clarify the character of the short-lived radical-pair (RP) intermediates generated from the photosensitized reduction of 2,5-di-t-butyl-1,4-benzoquinone and the oxidation of 2,5-di-t-butylhydroquinone by xanthene dyes using FT-EPR spectroscopy. Unusual absorptive electron spin polarization and heavy atom effects were observed in a former photoreduction system, indicating the production of contact RP as the reaction intermediate. Absorptive polarization is created by sublevel selective back electron transfer in the triplet contact RP due to the spin-orbit coupling interaction. On the other hand, it has also been shown that for the photooxidation system a pure RP mechanism is operative to create spin polarization, suggesting the generation of a solvent separated RP as an intermediate. The reaction rate constants for electron transfer and hydrogen abstraction reactions were also determined by analyses of the time profile of the chemically induced electron spin polarization spectra.
  • Teruhisa Komura, Takahiro Usui, Kousin Takahasi
    1995 Volume 68 Issue 12 Pages 3391-3396
    Published: 1995
    Released: July 10, 2006
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    From measurements of the a.c. response of polypyrrole film electrodes in KNO3 solution, we found that solvent swelling of the polymer greatly influences the kinetic behaviors of the polymer film electrodes. Electric migration in bulk film was due to background electrolyte ions which permeated through the film. Inside the film in contact with a supporting electrolyte solution, the mobility of the electrons may be much smaller than that of ions. The charge-transfer resistance of a partially oxidized film decreases along with increasing concentration of the electrolyte solution, because of a resultant increase in the activity of polarons. Such an increased activity of polarons also brings about a smaller Warburg coefficient, and thus a smaller limiting diffusion resistance (RL). The pseudocapacitance appearing at low frequencies increases along with an increase in the concentration of the electrolyte solution, which is opposed to the change in RL. These results corroborate that variations in the charge-transport parameters with the electrolyte concentration can be ascribed to an increase in the polaron activity with increasing ion concentration inside the polymer film.
  • Masazumi Ishikawa, Hiroaki Misawa, Noboru Kitamura, Masahiro Irie, Hir ...
    1995 Volume 68 Issue 12 Pages 3397-3402
    Published: 1995
    Released: July 10, 2006
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    Photostimulated volume expansion of polyacrylamide microgels (initial radius = 11—235 μm) bearing triphenylmethyl cyanide moieties (AAm-TPMCN) in water was studied on the basis of simultaneous measurements of the degree of ionic dissociation (α) of TPMCN to TPM+ (triphenylmethyl cation) and the gel radius. The time profile of the radius change, r(t), was analyzed by a convolution relation between r(t) and the time course of α (α(t)). The characteristic time constants of the volume change, related to the cooperative diffusion coefficient of the gel network, were determined for AAm-TPMCN gels with various radii. The faster photoresponse time of the volume change for the smaller AAm-TPMCN gel was explained in terms of the diffusion theory of gel networks in water.
  • Shozi Mishima, Tsuyoshi Nakajima
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3403-3410
    Published: 1995
    Released: July 10, 2006
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    A thermodynamic interpretation is presented of the convergent linear relationships observed among the log K (K; equilibrium constant) values of 1 : 1 hydrogen-bond complexation of nine OH– and NH–acids against five phosphorus compounds in CCl4. Straight lines converging on a single point are plotted from the log K values at different temperatures. The slopes of the lines correspond to the temperature ratio and the convergence point reflects the apparent constant value of ΔS° (−35.4 J mol−1 K−1). Sets of family-independent or family-dependent straight lines all of which converge on the same point can be plotted from the log K values of the acids (or bases) against two reference bases (or acids). The convergence point also reflects the constancy of the apparent ΔS° value and the slopes of the lines correspond to the ΔH° ratio. The thermodynamic features can be correlated with local structures of the acids and bases. The interpretation presented here can be applied to other systems and is of importance as a new view of 1 : 1 hydrogen-bond systems.
  • Hong Cao, Yukimi Akimoto, Yoshihisa Fujiwara, Yoshifumi Tanimoto, Li-P ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3411-3415
    Published: 1995
    Released: July 10, 2006
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    The photoinduced intramolecular energy-transfer (ET) reaction between benzophenone (BP) and norbornadiene (N) covalently bonded by a rigid steroid bridge in acetonitrile has been studied by laser flash photolysis. The ET rate constant for the excited triplet BP (3BP*) to N is 6.1 × 104 s−1, whereas the constant for the intramolecular hydrogen atom abstraction of 3BP* from the steroid is 1.91 × 105 s−1.
  • Fumio Shimizu, Kazumasa Yoshikai, Yoshinori Nibu, Hiroko Shimada, Ryoi ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3417-3421
    Published: 1995
    Released: July 10, 2006
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    The temperature effect on the low-frequency Raman bands of the four deuterated p-xylene crystals indicates that the coupling between the intramolecular torsional vibration of the CD3 group and the intermolecular rotational vibrations takes place below about −80 °C.
  • Nobuhiro Ide, Takeshi Fukuda, Takeaki Miyamoto
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3423-3428
    Published: 1995
    Released: July 10, 2006
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    Cellobiose octa(decanoate), a discotic columnar mesogen, was found to form in hexadecane solution various molecular assemblies such as a lyotropic liquid crystal of discotic columnar type, multimolecular micelles, and a thermoreversible gel, depending on the concentration and temperature. The gelation, observed even at very low concentrations, say, < 0.01 weight fraction of the mesogenic compound, is believed to proceed by local coagulation of long threadlike micelles into micro-liquid-crystallites, which work as cross-linking points combining the threadlike micelles. This will be a new type of gel that could be termed a “liquid crystalline gel.”
  • Tatsuya Sekine, Junko Tsuda
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3429-3437
    Published: 1995
    Released: July 10, 2006
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    The solvent extraction of thallium(I) in aqueous 0.1 mol dm−3 sodium nitrate solutions with seven chelating extractants [(HA), 1-phenyl-1,3-butanedione (Hbza); 1,3-diphenyl-1,3-propanedione (Hdbm); 4,4,4-trifluoro-1-phenyl-1,3-butanedione (Hbfa); 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione (Htta); 2-hydroxy-4-isopropyl-2,4,6-cycloheptatrien-1-one (Hipt); 5,7-dichloro-8-quinolinol (Hdcox); and 1,1,1-trifluoro-4-mercapto-4-(2-thienyl)-3-buten-2-one (Hstta)] into chloroform was studied in the absence and presence of tetrabutylammonium ions (tba+) or trioctylphosphine oxide (TOPO). The TlA type chelates were extracted, and, except for Hbza and Hdbm, tba+TlA2-type ternary complexes were extracted. However, the extraction of adduct chelates with TOPO was not obtained. A comparison of the stability, liquid–liquid partition, and acceptability of a further ligand in the organic phase was made with TlA, AgA, and LiA when A was 1,1,1-trifuluoro-3-(2-thienyl)-2,4-butanedionate ion (tta) and the ligand was TOPO or tta.
  • Ryo Miyamoto, Susumu Sudoh
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3439-3443
    Published: 1995
    Released: July 10, 2006
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    The electron paramagnetic resonance spectra of some gadolinium(III)-β-diketonate complexes were observed as frozen solutions. The observed spectra differ from each other upon changing the ligands, indicating that a change of the ligand fields and/or coordination structure of the ligands has a great effect on the behavior of the inner 4f electrons. Zero field splitting (ZFS) parameters were estimated by spectral simulations for the 8S7/2 system. The EPR spectral simulations attempted so far indicate that at least the ZFS parameter (|D|) for the Gd(hfa)3 complex is much smaller than that for other complexes, such as Gd(acac)3.
  • Kan Kanamori, Junko Kumada, Mayumi Yamamoto, Takako Okayasu, Ken-ichi ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3445-3451
    Published: 1995
    Released: July 10, 2006
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    The crystal structures of K[V(eddda)]·2H2O (1) and [V(β-alada)(H2O)2]·H2O (2) were determined by X-ray crystallography, where eddda and β-alada denote 1,2-diaminoethane-N,N′-diacetate-N,N′-dipropionate and N,N-bis(carboxymethyl)-β-alanate, respectively. The crystal of 1 is monoclinic, space group P21/n, a = 10.2753(8), b = 11.3007(8), c = 15.278(2) Å, β = 104.857(9)°, V = 1714.7(3) Å3, Z = 4, and R = 0.052. The crystal of 2 is orthorhombic, space group P212121, a = 7.451(1), b = 11.852(2), c = 13.403(2) Å, V = 1183.6(3) Å3, Z = 4, and R = 0.053. Complexes 1 and 2 adopt a hexacoordinate structure in contrast to the heptacoordinate one of the closely related ethylenediamine-N,N,N′,N′-tetraacetate and nitrilotriacetate complexes. Complexes 1 and 2 yield oxo-bridged dinuclear complexes upon base hydrolysis. The reaction of 2 with CO32− results in the formation of the heptacoordinate species with the bidentate carbonato ligand.
  • Kazuo Kashiwabara, Yuji Ozeki, Masakazu Kita, Junnosuke Fujita, Kiyohi ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3453-3457
    Published: 1995
    Released: July 10, 2006
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    An air and thermally stable iron(II) complex of 1,1,1-tris(dimethylphosphinomethyl)ethane (mmtp), [Fe(mmtp)2](BF4)2·2H2O, has been prepared, and the crystal structure has been determined by X-ray analysis. The complex was crystallized in the orthorhombic, space group Pca21 with four molecules in a unit cell of dimensions a = 17.448(4), b = 17.574(4), c = 11.367(2) Å, and V = 3485(1) Å3. Final R was 0.047 for 1671 reflections. The average Fe–P bond length of 2.312(5) Å is intermediate between those of [Co(mmtp)2][Co(CN)6]·2.25H2O (av Co–P = 2.331(9) Å) and [Cr(mmtp)2] (av Cr–P = 2.287(1) Å), in which Fe(II), Co(III), and Cr(0) have the same low-spin d6 electron configuration. A less stable dimeric complex, [Fe2(μ-Cl)3(mmtp)2]B(C6H5)4·H2O, has also been isolated. Absorption spectra and cyclic voltammograms have been compared between the Fe(II) and Co(III) complexes.
  • C. Devendranath Reddy, B. Sankara Reddy, K. Anuradha, K. D. Berlin, S. ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3459-3464
    Published: 1995
    Released: July 10, 2006
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    The syntheses of 2,10-dichloro-6-alkoxydibenzo[d,g][1,3,6,2]dioxathiaphosphocin 6-oxides are described. Their IR, 1H, 13C, and 31P NMR spectral characteristics are reported. Long-range couplings (2JPOC and 3JPOCC) between phosphorus and carbons were observed. An X-ray diffraction analysis of a crystal of 2,10-dichloro-6-ethoxydibenzo[d,g][1,3,6,2]dioxathiaphosphocin 6-oxide indicated a boat-chair conformation to the dioxathiaphosphocin ring with the phosphoryl oxygen in axial and the ethoxy group in equatorial orientations. The molecule possesses a symmetry of the mirror plane passing through the sulfur, phosphorus, phosphoryl oxygen, and ethoxy group.
  • Hiroaki Okamura, Tetsuo Iwagawa, Munehiro Nakatani
    1995 Volume 68 Issue 12 Pages 3465-3467
    Published: 1995
    Released: July 10, 2006
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    Two known lindenane sesquiterpenoids, chloranthalactone F and chloranthalactone A photodimer, were identified to be the same by direct comparison of the samples and their spectra. Both of their structures were revised to a new structure, head-to-head, anti dimer of chloranthalactone A, from the spectroscopic and chemical studies. Chloranthalactone A photodimer has been reported as an artifact, but this compound was observed as a natural product in the leaves of Chloranthus glaber.
  • Kazuaki Fukushima, Toshikazu Ibata
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3469-3481
    Published: 1995
    Released: July 10, 2006
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    The Rh2(OAc)4-catalyzed reactions of α-diazocarbonyl compounds in nitrile in the presence of dimethyl acetylenedicarboxylate (DMAD) gave oxazole and pyrrole derivatives. The formation of the oxazole derivatives is explained in terms of the 1,5-cyclization of an acyl-substituted nitrile ylide intermediate, and the formation of the pyrrole derivatives is explained by the 1,3-dipolar cycloaddition of the same intermediate with DMAD. The regiochemistry of the cycloaddition of the acyl-substituted nitrile ylide with methyl propiolate showed that the contribution of an allenyl-type resonance structure plays an important role in the acyl-substituted nitrile ylide reaction.
  • Tsuyoshi Ikeda, Satoko Fujiwara, Junei Kinjo, Toshihiro Nohara, Yoshit ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3483-3490
    Published: 1995
    Released: July 10, 2006
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    The structures of Julibrosides I, II, and III, isolated from dried stem bark of Albizzia julibrissin DURAZZ (Albizziae Cortex), were characterized as complex triterpenoidal glycosides linked to the monoterpene glycoside dimer, mainly by means of an NMR spectroscopic method. These compounds have a common structure comprising from acacic acid, the (6S)-2-trans-6-hydroxy-2,6-dimethy1-2,7-octadienoyl-6-O-quinovopyranoside dimer, and α-L-arabinofuranosyl-(1→4)-[β-D-glucopyranosyl-(1→3)]-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside. The diversity of the oligosaccharides attached to the C-3 hydroxyl group of acacic acid, an oleanane-type triterpene, makes a distinction between Julibrosides I, II, and III.
  • Hiroshi Sakamaki, Noriyuki Kameda, Tsukasa Iwadare, Yoshiyuki Ichinohe
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3491-3495
    Published: 1995
    Released: July 10, 2006
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    The reaction of allylic alcohols in benzene–methanol (3 : 2) solvent in the presence of cis-dichlorobis(triphenylphosphine)platinum(II)–tin(II) chloride dihydrate complex catalyst afforded allylic methyl ethers. The structure of the obtained compounds was identified by direct comparison with authentic sample. Cholest-4-en-3α-ol, with a quasi-axial hydroxy group, gave a quantitative yield of 3α-methoxycholest-4-ene. On the other hand, cholest-4-en-3β-ol, with a quasi-equatorial hydroxy group, yielded 3β-methoxycholest-4-ene preferentially, but it also yielded 3α-methoxy compound as a by-product, lowering the selectivity of the reaction.
  • Masaharu Tsuji, Masato Aizawa, Yukio Nishimura
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3497-3505
    Published: 1995
    Released: July 10, 2006
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    The gas-phase ion-molecule reactions of CF3+ with benzene, toluene, ethylbenzene, styrene, and ethynylbenzene have been studied at near-thermal energy using an ion-beam apparatus. The major product channels are electrophilic addition followed by HF elimination for benzene (93.4 ± 2.2%), toluene (84.3 ± 2.4%), and ethynylbenzene (76.9 ± 0.9%). The dominant product channels for ethylbenzene are electrophilic addition followed by C2H4 and C2H4+HF eliminations (78.9 ± 4.7%), while those for styrene are electrophilic addition followed by one or two HF eliminations and C2H2F2 elimination (91.7 ± 5.4%). Only ethynylbenzene gives an initial adduct ion with a small branching ratio of 6.2 ± 0.4%. As minor product channels, hydride transfer occurs for benzene (6.6 ± 2.2%) and toluene (7.8 ± 1.5%), and charge transfer takes place for toluene (7.9 ± 2.0%), styrene (8.3 ± 1.4%), and ethynylbenzene (6.2 ± 0.4%). The reaction mechanisms are discussed on the basis of product ion distributions and semi-empirical calculations of potential energies of reaction pathways.
  • Yasuyuki Kawahara, Shinzi Kato, Takahiro Kanda, Toshiaki Murai, Masahi ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3507-3517
    Published: 1995
    Released: July 10, 2006
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    A series of rubidium and cesium tellurocarboxylates (2 and 3) were synthesized from the reaction of O-trimethylsilyl tellurocarboxylates (1) with rubidium and cesium fluorides in moderate isolated yields and characterized by 1H, 13C, and 125Te NMR spectroscopy and X-ray diffraction. The carbon–oxygen distance [1.235(6) Å] of the tellurocarboxyl group of crystalline cesium 2-methoxybenzenecarbotelluroate (3f) showed a typical value of the carbon–oxygen double bond. The crystal packing of 3f shows the possibility of an interaction between the cesium cation and the aromatic ring carbon. The thio- and selenocarboxyl groups of the corresponding sulfur and selenium isologues (4 and 5) also indicate a double bond [1.231(4) and 1.226(5) Å] between the carbon and oxygen, respectively. The salts (2 and 3) readily react with iodomethane to afford the corresponding Te-methyl tellurocarboxylates in good yields. The reaction between 3 and tetramethylammonium chloride was found to give a novel quaternary ammonium salt (8) of tellurocarboxylic acid, where the dihedral angle between benzene ring and the tellurocarboxyl group of 8 is ca. 90°. Crystallographic data for 3f, 4, 5, and 8 are as follows. 3f: P21/n, a = 7.182(2), b = 12.161(5), c = 12.151(3) Å, β = 92.57(2)°, V = 1060.2(6) Å3, dcalcd = 2.479 g cm−3, Z = 4, R = 0.035, Rw = 0.043. 4: Pbca, a = 8.995(2), b = 29.936(2), c = 7.291(1) Å, V = 1963.3(5) Å3, dcalcd = 2.030 g cm−3, Z = 8, R = 0.024, Rw = 0.021. 5: Pbca, a = 9.290(1), b = 30.207(2), c = 7.193(2) Å, V = 2018.5(3) Å3, dcalcd = 2.284 g cm−3, Z = 8, R = 0.029, Rw = 0.020. 8: P212121, a = 11.844(2), b = 14.014(2), c = 8.650(1) Å, V = 1435.8(3) Å3, dcalcd = 1.558 g cm−3, Z = 4, R = 0.044, Rw = 0.047.
  • Hiroyuki Higuchi, Seiken Kiyoto, Chiaki Sakon, Naoki Hiraiwa, Kaori As ...
    1995 Volume 68 Issue 12 Pages 3519-3538
    Published: 1995
    Released: July 10, 2006
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    14-Methyl-10,12-bisdehydro-4,9-methano-1H-[17]annulen-1-one, 14-methyl-10,12-bisdehydro-4,9-methano-1H-[19]annulen-1-one, and 16-methyl-12,14-bisdehydro-6,11-methano-1H-[21]annulen-1-one, as well as their methylated and benzannelated derivatives, were synthesized and their tropic properties were studied by NMR and UV spectra under neutral and acidic conditions. The tropicity in these compounds was found to be lower than in their non-bridged monocyclic counterparts. Thus the methano-bridge works to decrease the planarity of the peripherally conjugated system.
  • Kazuaki Ito, Katsuhiro Saito
    1995 Volume 68 Issue 12 Pages 3539-3547
    Published: 1995
    Released: July 10, 2006
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    1,3-Dipolar cycloaddition reactions of N-aryl-2,4,6-cycloheptatrien-1-imines with p-substituted benzonitrile oxides afforded [2+3]-type cycloadducts in considerable yields. A study of the substituent effect on the reaction rate revealed that the reactions proceeded through nucleophilic reactions of imines to nitrile oxides. Thermal isomerizations and addition reactions of the adducts showed that the contribution of a valence isomerization between cycloheptatriene and norcaradiene lay to the side of the cycloheptatriene form. A comparison of the UV spectra between the adduct and its derivative, which was reduced by catalytic hydrogenation, implies that the spiroconjugation between cycloheptatriene and a five-membered heterocyclic moiety causes a shift of the equilibrium.
  • Chung-gi Shin, Takeshi Kakusho, Kazushige Arai, Masashi Seki
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3549-3555
    Published: 1995
    Released: July 10, 2006
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    The enzymatic hydrolysis of N-protected dehydrodipeptide methyl esters (2) (Protect-ΔAA-AA-OMe) was first achieved, despite the requisite of the only neutral and large proteinic L-α-amino acid (AA) in the case using papain. Furthermore, the reverse enzymatic coupling of the C-component 2 with N-component α-amino acid anilides or dehydrodipeptide esters containing dehydrovaline (ΔVal) residue was also successful. Consequently, the present study suggests that the proteolytic enzyme papain is able to become a very useful tool for peptide synthesis by a coupling of the C-component dehydropeptide with N-component α-amino acid, peptide, or dehydropeptide.
  • Hideki Okamoto, Kyosuke Satake, Masaru Kimura
    1995 Volume 68 Issue 12 Pages 3557-3562
    Published: 1995
    Released: July 10, 2006
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    The electronic absorption spectrum of a 1,4-difluorobenzene–naphthalene biplanemer 1 exhibited a characteristic absorption band around 290 nm. This was attributable to intramolecular charge transfer interaction between the longicyclic conjugated π system and the benzene chromophore. The oxidation potential of 1 was 1.70 V (vs. Ag/AgCl), which was lower than those of the related compounds in which one of the double bonds of 1 was hydrogenated. Thermally, the biplanemer 1 underwent facile Cope rearrangement, followed by dehydrofluorination, to give 1-(4-fluorophenyl)naphthalene and 2-(3-fluorophenyl)naphthalene.
  • Hisaji Taniguchi, Yoshio Otsuji, Eisaku Nomura
    1995 Volume 68 Issue 12 Pages 3563-3567
    Published: 1995
    Released: July 10, 2006
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    The formation of ethers was catalyzed by 5,11,17,23,29,35-hexa-p-t-butyl-37,38,39,40,41,42-hexakis(3,6,9-trioxadecyloxy)calix[6]arene (1). It was found that the calixarene-catalyzed reaction of phenol with benzyl bromide in the presence of KOH in CH2Cl2 yields only the O-alkylated product and this reaction proceeds according to Michaelis–Menten type kinetics. The calixarene 1 also catalyzed the reactions of phenols with dichloromethane and 1-chloro-4-nitrobenzene.
  • Makoto Matsui, Norio Karibe, Kenji Hayashi, Hisashi Yamamoto
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3569-3571
    Published: 1995
    Released: July 10, 2006
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    Scandium(III) trifluoromethanesulfonate was found to be an efficient catalyst as a Lewis acid for the condensation reaction of trimethylhydroquinone with isophytol to afford α-tocopherol. The condensation reaction proceeded smoothly using only a 0.001 molar amount of the catalyst. The catalyst was easily recovered from an aqueous layer after the reaction was completed, and could be reused.
  • Akikazu Kakehi, Suketaka Ito, Shigetoshi Hayashi, Takashi Fujii
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3573-3580
    Published: 1995
    Released: July 10, 2006
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    The title compounds, 1,4-dihydropyrido[2,3-b]indolizin-4-one derivatives, were prepared in moderate to good yields via the N-formylation of some 3-acetyl-2-(alkylamino)indolizines with triethyl orthoformate and acetic anhydride in the presence of zinc chloride followed by the intramolecular dehydration of the resulting 3-acetyl-2-(N-alkylformamido)indolizines under strong alkaline conditions.
  • Takeshi Sugai, Atsuhito Kuboki, Shigeki Hiramatsu, Hanako Okazaki, Hir ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3581-3589
    Published: 1995
    Released: July 10, 2006
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    Sialic acid (N-acetylneuraminic acid) and KDN (3-deoxy-β-D-glycero-D-galacto-2-nonulosonic acid) play important roles in a variety of intercellular events. Extensive studies have been reported on the use of sialic acid aldolase as a catalyst to form the C–C bond between N-acetyl-D-mannosamine derivatives and pyruvic acid to give sialic acid and its analogs. However, the reported protocols have a significant drawback in terms of the tedious separation of the desired product from a large excess of pyruvic acid. We report here on a clean solution to this problem that relies on the utilization of pyruvate decarboxylase for catalyzing the decomposition of pyruvic acid into acetaldehyde and carbon dioxide to facilitate product isolation. Concerning our investigation to enhance the activity of this enzyme, we emphasized two points. One was a sufficient supply of cofactors for pyruvate decarboxylase; the other was an improvement of the enzyme reactor. As a result, the activity became nearly four-times as high as that previously reported. The combination of two enzymatic reactions worked well, affording sialic acid and KDN in 60% yield from N-acetyl-D-mannosamine and D-mannose, respectively. In addition, an efficient method for preparing N-acetyl-D-mannosamine by the epimerization of N-acetyl-D-glucosamine was established. Calcium hydroxide was found to be most effective for base-catalyzed epimerization.
  • Hiroshi Miyauchi, Naohito Ohashi
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3591-3598
    Published: 1995
    Released: July 10, 2006
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    A racemate of threo-2-(2,4-difluorophenyl)-2-[1-(methylthio)ethyl]oxirane was separated into two enantiomers by reaction with a chiral carboxylic acid, followed by separation of the resultant diastereomers, hydrolysis of the ester, and dehydration of the 1,2-diol to the oxirane. This new optical resolution method was applied to the synthesis of SM-9164, a biologically active enantiomer of antifungal agent SM-8668. Thus, the optically active isomer of SM-8668 was prepared efficiently in eight steps from m-difluorobenzene.
  • Akio Kayano, Yumi Yajima, Motohiro Akazome, Makoto Fujita, Katsuyuki O ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3599-3609
    Published: 1995
    Released: July 10, 2006
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    A novel synthetic route to highly substituted γ-lactones was achieved by an intermolecular radical addition to 4-(methylthio)-4-(p-tolylsulfonyl)-3-butenoic ester (1) and its 2-(ethoxycarbonyl) derivative (2), which were easily prepared from (methylthio)methyl p-tolyl sulfone. Upon the irradiation of a solution of 1 and benzophenone in an alcohol (R1R2CHOH), the 1-hydroxyalkyl radical (R1R2C–OH) was generated and added regiospecifically to the 3-position of 1 to form an adduct that led to a γ-lactone by spontaneous intramolecular condensation. Similarly, 2 reacted with the alcohol to give α-(ethoxycarbonyl)-γ-lactones. The alcohol, which is a high boiling liquid or solid, can be employed in the form of a solution (10 molar amounts in acetonitrile) without greatly lowering the reaction efficiency.
  • Shunji Ito, Miwako Fujita, Noboru Morita, Toyonobu Asao
    1995 Volume 68 Issue 12 Pages 3611-3620
    Published: 1995
    Released: July 10, 2006
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    In order to control the flipping ring of a molecular propeller and to obtain clear evidence of a one-ring flip mechanism, stable carbocations, di-1-azulenyl(1-naphthyl and 2-naphthyl)methyl cations, bis(3-methyl-1-azulenyl)(1-naphthyl (5b) and 2-naphthyl (6b))methyl cations, and bis(3,6-di-t-butyl-1-azulenyl)(1-naphthyl and 2-naphthyl)methyl cations were synthesized by hydride abstraction of the corresponding hydrocarbons. These cations showed extreme stabilities with high pKR+ values (10.3—12.7). The dynamic stereochemistries of 5b and 6b were studied by temperature-dependent 1H NMR spectra, which were analyzed by a flip mechanism. While the 1H NMR signals of 6b did not resolve satisfactorily, the low-temperature 1H NMR spectra of 5b showed that the flipping ring of the molecular propeller was controlled by a one-ring flip of the 1-naphthyl group. These analyses afforded clear evidence of the one-ring flip mechanisms of (1-azulenyl)methyl cations.
  • Minoru Sakurai, Hidetoshi Kawai, Yoshio Inoue, Akihiro Hino, Syouichi ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3621-3627
    Published: 1995
    Released: July 10, 2006
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    Trehalose-containing and -lacking yeast cells are prepared, and in vivo 1H NMR spectra are measured in order to investigate effects of this sugar on water structure in the cells. The T2 relaxation times for the intracellular water protons are measured as a function of water content in the yeast cells. The results indicate that the intracellular water is categorized into at least two groups: highly immobilized water (T2 5 ms), assigned to bound water, and intermediate water. One of the most important findings is that the relative population of bound water is drastically increased by the accumulation of trehalose. About 80% of the intracellular water in the trehalose-containing yeast cells is attributed to bound water. Similar results are obtained for trehalose-containing and -lacking model membranes prepared from dipalmitoylphosphatidylcholine (DPPC). Additionally, DSC measurements are carried out to examine effects of trehalose on the gel–liquid crystalline transition temperature of the DPPC membranes. On the basis of these results, a brief discussion is given about the role of trehalose as a stress tolerance-inducer in cells.
  • Eiichiro Hata, Tohru Yamada, Teruaki Mukaiyama
    1995 Volume 68 Issue 12 Pages 3629-3636
    Published: 1995
    Released: July 10, 2006
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    Olefins with a terminal double bond or conjugated with aromatic nucleus are successfully nitrated into nitro olefins in good-to-high yields on treatment with nitrogen monoxide (NO) in 1,2-dichloroethane. Nitro alcohols formed as by-products are dehydrated to yield nitro olefins by the subsequent treatment with acidic activated alumina. By GC analysis, it was confirmed that an equimolar amount of nitrogen gas was evolved during the present nitration. A possible reaction pathway including the formation of nitro nitroso compounds, key intermediates, is described. The key intermediates are transformed into nitro olefins by reaction with nitrogen monoxide.
  • Tsugio Kitamura, Ryuji Furuki, Lei Zheng, Kensuke Nagata, Takahiro Fuk ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3637-3641
    Published: 1995
    Released: July 10, 2006
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    A (p-phenylene)bisiodine(III) reagent prepared from iodosylbenzene and trifluoromethanesulfonic acid or the anhydride showed a high reactivity to alkynes. The reaction of alkynes proceeded with stereoselective addition to the carbon–carbon triple bond to give trans-alkenyl(p-phenylene)bisiodonium ditriflates, whereas the reaction of 1-trimethylsilyl-1-alkynes afforded alkynyl(p-phenylene)bisiodonium ditriflates. These reactions indicate that the (p-phenylene)bisiodine(III) reagent is accessible for a (p-phenylene)bisiodine(III) transfer agent.
  • Yasuharu Ishibashi, Shigeru Ohba, Shigeru Nishiyama, Shosuke Yamamura
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3643-3649
    Published: 1995
    Released: July 10, 2006
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    The absolute configuration of aureothin (1) has been determined by synthesis of (−)-aureonone (4) bearing R-configuration. X-Ray single crystallographic analysis of 21 guaranteed the stereochemistry of the chiral center introduced by Sharpless asymmetric epoxidation, as well as that of isoaureothin (3) which was previously synthesized in a similar pathway. Aureothin (1) itself was also synthesized, although Wittig coupling reaction of 4 under basic conditions, caused a partial epimerization of the chiral center.
  • Ashfaq Ahmed, S. G. Oak, V. S. Darshane
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3651-3657
    Published: 1995
    Released: July 10, 2006
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    The System CuCr2−xFexO4 has been studied with a view to correlate the catalytic behavior of spinels on the decomposition of cyclohexanol. All the compositions between 0.0 ≤ x ≤ 1.0 had cubic symmetry and p-type semiconductivity except the compound CuCr2O4 (x = 0.0) which showed tetragonal symmetry. The activation energy for the electronic conduction varied between 0.38 and 0.13 eV. The Seebeck coefficient (α) was found to increase with increases in ‘x’. Catalytic evaluation was done in the temperature range 200—400 °C using cyclohexanol as a probe molecule. Our results show CuCrFeO4 to be a better catalyst for cyclohexanol decomposition than CuCr2O4. The percent decomposition of alcohol increased with increases in mobility of charge carriers and decreases in values of activation energy. Further, dehydrogenation selectivity increased with increases in p-type behavior of the compositions from CuCr2O4 to CuCrFeO4. X-ray and IR studies indicated that the spinel catalysts are quite stable over the temperature range investigated.
  • Shanmugam P. Elangovan, Vengaimuthu Krishnasamy, Velayutham Murugesan
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 12 Pages 3659-3663
    Published: 1995
    Released: July 10, 2006
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    Nickel-substituted aluminophosphate molecular sieves (NAPO-5 and NAPO-11) were synthesized hydrothermally using triethylamine and dipropylamine as templates. Structures were confirmed by X-ray powder pattern, and unit cell parameters calculated by a standard least square refinement technique. The isomorphous substitution of nickel in the aluminophosphate framework is evidenced by the considerable increase in unit cell volume compared to unsubstituted AlPO4-5 and AlPO4-11. In addition, electron spin resonance and diffuse reflectance spectra were carried out to produce supporting evidence for the isomorphous substitution of nickel. Acidity was determined by a TPD-TGA method which shows two types of acid sites. Symmetry and asymmetry vibrations were obtained from infrared spectra. Chemical analysis by ICP and BET surface area are also reported. The physicochemical properties of the catalysts were correlated towards isomerisation of camphene at various (WHSV)−1 values and temperatures. The products formed are tricyclene and 2-bornene and the selective formation of tricyclene was achieved over these catalysts.
  • Takatoshi Seto, Katsufumi Kujira, Hiroshi Iwane, Makoto Imanari
    1995 Volume 68 Issue 12 Pages 3665-3670
    Published: 1995
    Released: July 10, 2006
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    In the liquid-phase synthesis of indole from aniline and ethylene glycol (EG), a CdBr2–KBr catalyst gave a high yield of indole. In recycling experiments using the catalyst in an autoclave, the yield of indole remained stable and the inorganic components of the catalysts did not suffer degeneration. The time course of the reaction under high pressure and high temperature was evaluated using a newly devised autoclave. The rate of formation of indole was determined to be proportional to the concentrations of both EG and the catalyst. Based on these findings for the reaction over CdBr2–3KBr, it is clear that this catalyst provides a simple and low-cost catalytic process for the formation of indole.
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