bluuebunny/crossref_metadata_2025_split huggingface dataset:
Layered Compounds. XVI. NMR Spectra of Multilayered [2.2]Paracyclophanes
Authors: Otsubo Tetsuo , Mizogami Shigeyoshi , Sakata Yoshiteru , Misumi Soichi 
Published: July 2006

Abstract
The NMR spectra of multilayered [2.2]paracyclophanes (I–XVI), in which benzene rings are closely stacked, have been examined. The assignment of the signals was made not only by integral strength, but also by solvent effect and the Nuclear Overhauser effect. The steric compression effect of transannular methyl groups on aromatic protons was observed in methylated cyclophanes. Enhanced ortho substitution shift was also observed. All the aromatic protons shift to remarkably higher field due to the anisotropy of stacked benzene rings as the number of layers increases. The shielding effect caused by these rings was empirically estimated.
Aminocyclitols. XXIX. Synthesis of Inosadiamines via 1,3-Biimino-1,3-dideoxy-inositols
Authors: Suami Tetsuo , Ogawa Seiichiro , Uchino Hayashi , Uchida Masaru 
Published: July 2006

Abstract
Hydrazinolysis of Dl-1,4-dibromo-1,4-dideoxy-chiro-inositol (3a), followed by catalytic hydrogenation and acetylation, afforded di-N-acetyl-tetra-O-acetyl-neo-inosadiamine-1,3 (6a) and -scyllo-inosadiamine-1,3 (7) in 18% and 24% yields, respectively. From the intact hydrazinolyzate of 3a, two new stereoisomeric 1,3-biimino-1,3-dideoxy-inositols (4a and 5a) could be isolated, and their structures were established by correlating to the corresponding inosadiamines. A similar hydrazinolysis of 3,6-di-O-p-tolylsulfonyl-muco-inositol (12) gave sole crystalline 1,3-biimino compound (13a), whose structure was followed from its conversion into known di-N-acetyltetra-O-acetyl-myo-inosadiamine-4,6 (14). PMR spectra of four 1,3-biimino compounds were discussed.
New Syntheses of Pyrimido[4,5-d]pyrimidines
Authors: Yoneda Fumio , Higuchi Masatsugu 
Published: July 2006

Abstract
Novel conversions of pyrrolo-pyrimidines into pyrimido-pyrimidines are described. The treatment of 5-nitrosopyrrolo-pyrimidine (I) under Beckmann conditions causes ring expansion to give pyrimido-pyrimidine (II). Both the reduction of I with triphenylphosphine, potassium pyrosulfite, or sodium dithionite in dimethylformamide and the oxidation of 5-aminopyrrolo-pyrimidine with lead tetraacetate in dimethylformamide or acetic acid afford II. 5-Aminopyrimido-pyrimidine is prepared by the nucleophile-induced ring expansion of I. The possible mechanisms of these ring expansions are proposed.
Condensation Reactions of Adenine Derivatives with 1-O-Acetyl-2,3,5-tri-O-benzoyl-β-d-ribofuranose in Nitrophenols
Authors: Nakazaki Nobuo , Sekiya Masao , Yoshino Teruo , Ishido Yoshiharu 
Published: July 2006

Abstract
Intermolecular interaction between nitrophenols, such as m-, p-nitrophenol, 2,4-dinitrophenol, and picric acid, and adenine derivatives, such as N(6)-benzoyladenine, N(6)-benzoyl-2-methylthioadenine, and N(6)-benzyladenine, was verified by the formation of the corresponding molecular compounds. On the basis of these results, condensation reactions of these adenine derivatives with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-d-ribofuranose were carried out in nitrophenols, which were used as the activating agents. They were proved to afford the corresponding nucleosides in good yields. In addition, a novel glycosyl rearrangement reaction was first observed in the case of the reaction of N(6)-benzyladenine with the ribofuranosyl acylate.
Tri(hetero)substituted Carbonium Ions. VIII. The Hydride Reduction of Cyclic and Open-chain Dithiocarbamidium Salts
Authors: Hiratani Kazuhisa , Nakai Takeshi , Okawara Makoto 
Published: July 2006

Abstract
Studies were carried out on the hydride reduction of the following five stable N,S,S-tri(hetero)substituted carbonium ions: N,N,S,S′-tetramethyldithiocarbamidium ion (1a), 2-dimethylamino-1,3-dithiolanylium ion (1b), 2-dimethylamino-1,3-dithianylium ion (1c), 2-methylthio-3-methyl-4,5-dihydrothiazolium ion (1d), and 2,3,5,6-tetrahydrothiazolo[2,3-b]thiazolium ion (1e). Sodium dihydrobis(methoxyethoxy)aluminate (RDB) was found to be a suitable reducing agent. The RDB reduction of the carbonium ions at −5 °C gave the corresponding formamide thioacetals (2) in moderate yields. This provides a practical method for the synthesis of formamide thioacetals. The RDB reduction of 1d at higher temperature, however, yielded abnormal products, thiazolin-2-thione (3) and thiazolidine (4) instead of the formamide thioacetal (2d). The mechanism for the formation of 3 and 4 has been discussed in terms of the ambident character of the cation (1d). Pyrolytic reactions of the thioacetals (2) and unsuccessful attempts to abstract the methine proton of 2b by various bases are also described.
The One-Electron Reduction of Carbonium Ions. V. A Kinetic Study on the Reduction of the Substituted Cyclopropenium Ions with Cr(II)
Authors: Okamoto Kunio , Komatsu Koichi , Hitomi Akira 
Published: July 2006

Abstract
The one-electron reduction of a series of phenyl- and/or n-propyl-substituted cyclopropenium ions with Cr(II) has been carried out in a 10% HCl solution. The reduction of triphenylcyclopropenium (Ia), diphenyl-n-propylcyclopropenium (Ib), and phenyldi-n-propylcyclopropenium (Ic) ions quantitatively gives dimers of the respective cyclopropenyl radicals, i.e., the bis(cyclopropenyl) derivatives, whereas the tri-n-propylcyclopropenium ion (Id) is quite unreactive. A kinetic study has shown that the reactivity of these stable carbonium ions toward the one-electron reductant (Cr(II)) is lowered with a decrease in the number of the phenyl substituent: k225°C=3.0×10−4l/g-ion·s for Ia, 2.7×10−6l/g-ion·s for Ib, 2.8×10−9l/g-ion·s for Ic, and &lt;10−11l/g-ion·s for Id. The added NaCl was found to accelerate the reduction rate of Ia, whereas the added HCl showed an initial rate enhancement effect, followed by a slight rate-retarding effect. A plot of logk2 against the electron affinities of the respective cations, estimated from the transition energies of the charge-transfer bands for Ia,b with pyrene, has been found to fit a linear correlation previously obtained for a series of tropylium ions. The values of logk2 also exhibit a linear free-energy relationship with the pKR+ of these cations.
Solubility of Alkyl Bromides in Aqueous Polymer Solutions
Authors: Okubo Tsuneo , Chen Shou-Xyng , Ise Norio 
Published: July 2006

Abstract
The solubility of alkyl bromides (alkyl : ethyl, n-propyl, n-butyl and n-amyl) in aqueous solutions of neutral polymers and polyelectrolytes was measured and discussed. The polymers used were polyacrylamide (PAAm), polyvinylalcohol(PVA), polyethyleneglycol (PEG), polyvinylpyrrolidone(PVP), polyethylenimine(PEI) and polyacrylic acid(PAA) and its salts. The solubility of alkyl bromide increased linearly with concentration of neutral polymer in the order PAAm&gt;PVP∼PEI&gt;PEG&gt;PVA∼PAA. Sodium salt of PAA decreased the solubility of alkyl bromide, but organic salts of PAA such as tetraalkylammonium salts increased it. Using the equation In (So⁄S)=km2, the limiting Setchénow constant k was obtained for these systems. The results were accounted for in terms of the hydrophobic structural modifications of water and the direct dipole and/or hydrophobic interactions between solute and cosolute.
Comparison of the Conductance Equations of Fuoss-Onsager, Fuoss-Hsia and Pitts with the Data of Bis(2,9-dimethyl-1,10-phenanthroline)Cu(I) Perchlorate
Authors: Miyoshi Katsuhiko 
Published: July 2006

Abstract
Conductance equations derived by Fuoss-Onsager (1965), Fuoss-Hsia (1967) and Pitts (1953) were compared using the conductance data of bis(2,9-dimethyl-1,10-phenanthroline)Cu(I) perchlorate in acetonitrile, nitrobenzene and nitromethane at 25°C, which have relatively high dielectric constant. The chelate salt was found to be completely dissociated in these solvents. Though the Pitts equation was found to reproduce the data more satisfactorily than the Fuoss-Onsager (F–O) and the Fuoss-Hsia (F–H) equations, the derived distance of the closest approach a from the Pitts equation was unrealistically small for the bulky complex salt. It was shown that the F–H equation is preferable for the analysis of conductance data for both associated and unassociated electrolytes.
Kinetic Studies of the Dissociation and the Recombination Reaction in Aqueous Solutions of Monocarboxylic Acids by Means of Ultrasonic Absorption Measurements
Authors: Sano Takayuki , Miyazaki Tomohiro , Tatsumoto Nobuhide , Yasunaga Tatsuya 
Published: July 2006

Abstract
The ultrasonic absorptions were measured in aqueous solutions of acetic, propionic, butyric, valeric, and chloroacetic acids as a function of the pH over the frequency range from 1.5 to 220 MHz at 25°C. From the dependences of μ′max and fr on pH, it was deduced that the perturbation of the ionization equilibrium of acids was the cause of the excess absorptions in dilute aqueous solutions. The kinetic parameters thus calculated were compared with those obtained by other methods.
Spectrophotometric Study on the Extraction of the Ternary Complex Composed of Vanadium(V), 8-Hydroxyquinoline-5-sulfonic Acid and Zephiramine
Authors: Kambara Tomihito , Sugawara Masao 
Published: July 2006

Abstract
The ternary complex composed of vanadium(V),8-hydroxyquinoline-5-sulphonic acid (H2QS), and zephiramine (Z+Cl−) was extracted into chloroform. The absorption maxima of the ternary complex in the organic layer were 375 and 580 nm at pH 2.8 and 375 nm at pH 4.8. The optimum pH range for the extraction was 4.5–5.4. Beer’s law held for 1.29–35.6 μg of vanadium(V). The molar absorptivity of the complex was 0.99×104 cm−1 mol−1 l. The composition of the ternary complex was estimated to be [VO2+Z+(QS2−Z+)2]o and the extraction equilibrium was given by
VO2++2[(HQS−Z+)]o+Z++2OH−\ightleftharpoons[VO2+Z+(QS2−Z+)2]o+2H2O (1)
The logarithm of the equilibrium constant K of this equation was found to be 32.57±0.49.
The Reaction of Propargyl Compounds with Carbon Monoxide and Water in the Presence of Iron Carbonyl Catalyst
Authors: Wada Fumio , Matsuda Tsutomu 
Published: July 2006

Abstract
The reaction of propargyl alcohol as well as its acetate and methyl ether with carbon monoxide and water in the presence of ironpentacarbonyl-amine catalyst under oxymethylation conditions proved to proceed at a much faster rate than that of 1-butyn-4-ol, 1-pentyn-5-ol and alkylacetylenes accompanied by elimination of the functional groups at C-3 to give dimethyl methylsuccinate. 3-Methyl-1-butyn-3-ol and 1-ethynylcyclohexanol reacted in a similar manner, but gave mixtures of unsaturated monoesters and diesters, saturated and unsaturated. The faster rate of reaction and the product obtained were interpreted by a scheme involving a concerted attack of hydroirontetracarbonyl anion, HFe(CO)4−, at the terminal position to split off the group at C-3. The mononuclear hydrido anion was assumed to be an active catalytic species in the reaction on the basis of both the infrared spectra of the catalyst system under the reaction conditions and the efficiency of potassium hydroxide as a base component.
The Reactions of Stannic Halides with Some Triphenylphosphine, -arsine and -stibine-substituted Iron Carbonyls
Authors: Takano Tetsuo 
Published: July 2006

Abstract
The reactions of stannic chloride and bromide with triphenylphosphine, -arsine and -stibine tetracarbonyl iron(0) undergo oxidative-elimination reactions to afford new binuclear organometallic compounds in good yields; Fe(CO)4EPh3+SnX4→Fe(CO)3EPh3SnX4+CO (E=P, As, Sb; X=Cl, Br; Ph=C6H5), where one molecule of carbon monoxide is discharged. The complexes are characterized by elemental analysis, by infrared and Mössbauer spectroscopies, and by conductivity measurements; these data are used to predict their possible formulation as nonionic, hexa-co-ordinate iron derivatives of the Fe(CO)3(X)(EPh3)(SnX3) type containing a tin-to-iron metal-metal bond.
The Crystal Structures of Methyl Bromide and Methyl Iodide
Authors: Kawaguchi Takemi , Hijikigawa Masaya , Hayafuji Yoshinori , Ikeda Masashi , Fukushima Reizo , Tomiie Yujiro 
Published: July 2006

Abstract
The crystal structures of methyl bromide and methyl iodide have been determined by the X-ray diffraction method at about −120°C and about −80°C respectively. Both the crystals are isomorphous, with orthorhombic space group D2h16–Pnma. Unit cells containing four molecules have the dimensions: a=4.474(1), b=6.420(2), and c=9.150(1) Å for methyl bromide, and: a=4.597(2), b=6.987(1), and c=10.117(1) Å for methyl iodide. These structures are quite different from that of methyl chloride, which has a symmetry of C2v12–Cmc21. In the three crystals, all the molecules are found on the mirror planes; the difference lies in the mutual orientations of the molecules.
Substituent Effects on Dissociation Constants of 4-and 6-Styryl-2-aminotropones
Authors: Imafuku Kimiaki , Matsumura Hisashi 
Published: July 2006

Abstract
The dissociation constants of two series of 4- and 6-styryl-2-aminotropones were measured spectrophotometrically in 50% aqueous methanol at 20°C. It was found that Hammett’s free energy relationship is applied to the analysis of substituent effects, with ρ=0.59 and 0.40, respectively, and that there is a difference between the electronic effects of the two isomers.
Putranjic Acid. Synthesis and Stereostructure
Authors: Aoyagi Reiko , Moriyama Yoshihiko , Tsuyuki Takahiko , Takahashi Takeyoshi 
Published: July 2006

Abstract
Putranjic acid, isolated from Putranjiva roxburghii has been synthesized from friedelane-2,3-dione and has been shown to be (2S)-2-hydroxy-3,4-seco-friedelan-3-oic acid.
New Syntheses of Maculosidine and Pteleine
Authors: Sekiba Tetsuya 
Published: July 2006

Abstract
2,3-Dihydromaculosidine and 2,3-dihydropteleine were obtained from 2,4-dimethoxy- and 4-methoxy-aniline by condensation with diethyl β-benzyloxyethylmalonate, followed by methylation and subsequent cyclodebenzylation with polyphosphoric acid. The dehydrogenation of the dihydro compounds with 2,3-dichloro-5,6-dicyanobenzoquinone gave maculosidine (4,6,8-trimethoxyfuro[2,3-b]quinoline) and pteleine (4,6-dimethoxyfuro[2,3-b]quinoline) in relatively high yields. Similarly, evolitrine (4,7-dimethoxyfuro[2,3-b]quinoline) and γ-fagarine (4,8-dimethoxyfuro[2,3-b]quinoline) were also prepared.
The Syntheses of Trimethyl dl-(Methoxycarbonylmethyl)-1,2,4-cyclopentanetricarboxylates
Authors: Ito Shosuke , Hirata Yoshimasa 
Published: July 2006

Abstract
The five trimethyl dl-3-methoxycarbonylmethyl-1,2,4-cyclopentanetricarboxylates have been synthesized and their configurations determined. A comparison of their spectral properties with those of the corresponding ester obtained from ikarugamycin indicates that the latter has a cis, trans, trans configuration.
Tubercidin. Its Conversion into 5′-Deoxytubercidin
Authors: Anzai Kentaro , Matsui Masanao 
Published: July 2006

Abstract
Tubercidin (I) was converted into 5′-deoxytubercidin (IV). Mesylation of 2′,3′-O-isopropylidenetubercidin (IX) afforded-2′,3′-O-isopropylidene-5′-O-mesyltubercidin (XVIII), which in situ was treated with benzoyl chloride. The product, N6,N6-dibenzoyl-2′,3′-O-isopropylidene-5′-O-mesyltubercidin (XXII), was converted into N6,N6-dibenzoyl-5′-deoxy-5′-iodo-2′,3′-O-isopropylidenetubercidin (XXIV). Catalytic hydrogenation of XXIV afforded N6-benzoyl-5′-deoxy-2′,3′-O-isopropylidenetubercidin (XXVII). 5′-Deoxytubercidin (IV) was obtained on debenzoylation and deacetonation of XXVII.
The Crystal Structure of Methylene Bichloride, CH2Cl2
Authors: Kawaguchi Takemi , Tanaka Kazuo , Takeuchi Toru , Watanabé Tokunosuké 
Published: July 2006

Abstract
The crystal structure of methylene dichloride has been determined by the X-ray diffraction method at about −120°C. The structure has a symmetry D2h14–Pbcn, and its orthorhombic tetramolecular cell has these dimensions: a=4.249±0.001, b=8.138±0.020, and c=9.492±0.002 Å. The positional parameters of the chlorine and carbon atoms are obtained by a three-dimensional Patterson function, followed by a least-squares refinement including the hydrogen atom. The structure thus obtained is in excellent agreement with the results of lattice-energy calculations. The crystal structure is quite different from that of methylene dibromide (and of methylene diiodide).
The Vacuum Ultraviolet Photolysis of Liquid n-Hexane in the Presence of SF6
Authors: Pitchoozhkin Vadim I , Yamazaki Hideo , Shida Shoji 
Published: July 2006

Abstract
The photolysis of liquid n-hexane has been studied at room temperature and at −78°C by using the resonance lines of Xe and Kr. The main process is hydrogen detachment, giving the same amount of hydrogen and of hexenes; relatively small amounts of the decomposition and dimer products were also formed. Upon the addition of SF6, the yield of the hydrogen detachment decreased strongly with an increase in the concentration of SF6, and then approached a constant value of 0.65 relative to that in pure n-hexane. The total amount of fluorinecontaining products detected in the presence of SF6 was relatively small compared with the amount of the decrease in the hydrogen detachment. As another electron scavenger, C6H13F was also tested; here, the decrease in the hydrogen detachment was quite small.
Luminescence from 2,3-Dimethylbutane Containing Toluene in the Solid Phase at 77°K during γ-Irradiation
Authors: Miyazaki Tetsuo , Saitake Yoshiyuki , Kuri Zen-ichiro , Sakai Shigenori 
Published: July 2006

Abstract
The luminescence from 2,3-dimethylbutane(2,3DMB) containing toluene in the solid phase has been measured at 77°K during γ-irradiation. The emission consists of fluorescence and phosphorescence from toluene. Since the emission becomes zero upon the removal of a γ-ray source, it cannot be due to a post-irradiation effect. It is concluded from the dependency of the intensity on the concentration of toluene that the luminescence is due to an intermolecular energy transfer from 2,3DMB to toluene during γ-irradiation. ESR studies of γ-irradiated 2,3DMB containing toluene have also been undertaken at 77°K in order to obtain some information on the intermolecular energy transfer. The toluene anion is formed in the γ-irradiated 2,3DMB containing toluene. The dimer cation of toluene is formed in the γ-irradiated 2,3DMB containing toluene and an electron scavenger. The luminescence from toluene in the 2,3DMB matrix decreases upon the pre-irradiation of the sample at 77°K. When the pre-irradiated sample is illuminated by the light from a tungsten lamp to photobleach the toluene anion, the luminescence during γ-irradiation is recovered. Since the intensity of the luminescence does not correspond at all to the amount of toluene anions, the luminescence from toluene in the 2,3DMB matrix during γ-irradiation must not be due to a neutralization reaction between a toluene anion and a migrating hole. It is suggested that the migration of energy from the irradiated 2,3DMB to toluene may occur via an excitation transfer reaction.
The Crystal Structure of Di-π-allyl(dihydropentalenylene)dinickel
Authors: Kitano Yukishige , Kashiwagi Michio , Kinoshita Yukio 
Published: July 2006

Abstract
The crystal structure of di-π-allyl(dihydropentalenylene)dinickel, (C8H6)Ni2(C3H5)2, has been determined from three-dimensional single-crystal X-ray photographic data. The crystal of this compound is composed of discrete molecular units in the monoclinic space group P21/a, with two molecules per unit cell with dimensions of a=8.451±0.004, b=12.691±0.005, c=5.976±0.006 Å, and β=108.81±0.05°. The calculated and observed densities are 1.650 and 1.60 g·cm−3 respectively. The structure was deduced from a sharpened Patterson synthesis and was refined by means of the least-squares method to the final R index of 0.121 for 1151 independent non-zero reflections. The molecule has a crystallographic center of symmetry; therefore, two nickel atoms which are complexed in a sandwich fashion between the dihydropentalenylene ring and the π-allyl group take a trans configuration. The distances of the nickel atom from the ring carbons range from 2.03 to 2.27 Å, the closest approach being to the three non-bridging atoms of the five-membered ring. The orientation of the π-allyl groups with respect to the nickel atom is similar to those found in other π-allyl complexes.
Electron-spin-resonance Studies of the Formation and Properties of the Trimeric Vanadyl Dibutylphosphate Complex
Authors: Sato Mitsuo , Takayanagi Teruo , Fujita Yuzaburo , Kwan Takao 
Published: July 2006

Abstract
The extraction of the vanadyl ion (VO2+) from aqueous solutions by di-n-butylphosphoric acid ((C4H9O)2-PO2H) in hexane has been studied by ESR. It has been found that monomeric and trimeric vanadyl di-n-butylphosphate complexes were present in the organic phase, and the equilibrium constant of the reaction involving monomeric and trimeric forms was determined. The ESR spectrum of the trimeric complex, characterized by 22 hf lines with a separation of 39 gauss, was interpreted as resulting from the magnetic exchange interaction between three vanadyl ions. A crystalline vanadyl complex was isolated from the hexane solution and found to be (VOX2)3, where X represents (C4H9O)2PO2−. The properties of the complex were investigated by means of ESR, IR, and the optical absorptions. The mechanism of the extraction of VO2+ by (C4H9O)2PO2H was discussed, and a cyclic model was proposed for the structure of (VOX2)3.
The Bromine Nuclear Quadrupole Resonance of Two Modifications of Indium Tribromide
Authors: Okuda Tsutomu , Furukawa Yoshihiro , Shigemoto Hiroko , Negita Hisao 
Published: July 2006

Abstract
The bromine nuclear quadrupole resonance study of indium tribromide has revealed that there are at least two modifications in its solid state. The high-temperature modification shows the two 81Br resonance lines of 85.985 and 86.205 MHz, with the relative intensity of 1 : 2 at 24.5°C. This modification was stable unless the temperature was lowered to ∼15°C. The low-temperature modification shows one 81Br resonance line, 86.915 MHz, at −196°C and was stable up to ∼30°C. The directions of the z axes of the field gradient were determined by studying the Zeeman effect on each resonance line of the two modifications at room temperature. For the two resonance lines of the high-temperature modification, one and two directions, which had the asymmetry parameters of 0.362 and 0.400 respectively, were observed. The resonance line of the low-temperature modification showed three directions with the asymmetry parameter of 0.387. The crystal structures of the high- and low-temperature modifications were, therefore, concluded to be monoclinic and hexagonal respectively, from the numbers of resonance lines and of the nonequivalent directions of the z axes. The quadrupole coupling constants and asymmetry parameters were analyzed by means of the Townes-Dailey method.
The Applicability of the Theory of R. A. Marcus to the Electron-Transfer Reactions between Polycyclic Aromatic Hydrocarbons and Their Anion Radicals
Authors: Suga Kosaku , Aoyagui Shigeru 
Published: July 2006

Abstract
The rates of electron-transfer from the anthracene-anion radical to anthracene, 1,2-benzanthracene, and pyrene are measured by the electron spin resonance method, with a line-broadening procedure, under experimental conditions in which anion radicals are in a state of free ions or of loose ion pairs. The dependence of the observed rate constants on the standard free energy of reaction, the dielectric constant of the solvent, and the temperature are discussed on the basis of the theory of R. A. Marcus. The free energy of nuclear reorganization, as estimated from the ΔG°-dependence of the rate constants, is much smaller than that predicted theoretically. The observed rate constants are almost independent of the dielectric constants of the solvents; consequently, the reorganization free energy of the solvent must be smaller than the theoretical value. The entropy term contributes to the activation energy to almost the same extent in the solvents with different dielectric constants; this is inconsistent with the theoretical prediction and requires a smaller value for the free energy of solvent reorganization than its theoretical value.