bluuebunny/crossref_metadata_2025 huggingface dataset:
Asymmetric Reduction with C1- and C2-Symmetric NADH Model Compounds Containing Chiral 1,1′-Binaphthyls
Authors: Amano Masaki , Watanabe Motoshi , Baba Naomichi , Oda Jun’ichi , Inouye Yuzo
Published: July 2006

The present study deals with Mg-catalyzed asymmetric reduction of ethyl benzoylformate by the use of C2-symmetric NADH model compounds in which axial dissymmetry (chiral 1, 1′-binaphthyl derivatives) was introduced as a chiral source for the first time and the results were compared with those obtained by the corresponding C1-symmetric models bearing the same chiral center. Better e.e.’s of the reduction product were obtained by the use of NADH models having C2-symmetry than does the corresponding C1 symmetric ones. Further, the kind of bonding as well as the distance between chiral binaphthyl and the reaction center affected the stereochemical course of hydrogen transfer.
The Base-catalyzed Condensation Reaction of Dimethyl Malonate with 5-Chloro-2-methoxytropone and 2,5-Dichlorotropone. On the Solvent Effect for the Sites of the Reaction
Authors: Nozoe Tetsuo , Takeshita Hitoshi , Tajiri Kozo
Published: July 2006

The sites of the nucleophilic attack of the base-catalyzed condensation of dimethyl malonate with 5-chloro-2-methoxytropone were solvent-dependent; the normal substitution product was predominant in benzene, but the ciné-substitution products were exclusive in methanol. With 2,5-dichlorotropone, the ciné-reaction products were exclusive in both solvents.
Vibrational Spectra of Organic Conductors. Charge Transfer Salts of TTF with Substituted p-Benzoquinones
Authors: Matsuzaki Susumu , Moriyama Toshiharu , Onomichi Mitsukazu , Toyoda Koichi
Published: July 2006

Charge transfer salts of tetrathiafulvalen (TTF) with five substituted p-benzoquinones (fluoranil, chloranil, bromanil, iodanil, and 2,3-dichloro-5,6-dicyano-p-benzoquinone) were prepared by diffusion and cooling methods. IR, Raman, and electronic spectra of these salts measured at room temperature showed that all except fluoranil salt formed two crystal phases, i.e., the diffusion and the cooling methods gave a mixed-valent and a monovalent ionic phases respectively. The degrees of charge transfer (ρ) of the mixed-valent salts were estimated from the Raman frequencies of ag ν3 of TTF, and nearly equal values (ca. 0.7) were obtained for all of them.
Studies on the β-Turn of Peptides. VIII. β-Turn Preferences of N-Acetyltetrapeptide Methylamides Related to the β-Turn Part of Gramicidin S
Authors: Sato Kazuki , Higashijima Tsutomu , Sugawara Rika , Nagai Ukon
Published: July 2006

N-Acetyl-l-Leu–X–l-Pro–l-Val methylamides (IIa: X=d-Ala, IIb: X=Gly, IIc: X=l-Ala) were synthesized and subjected to CD and 1H NMR measurements to study the β-turn preferences of these peptides. Temperature dependences of l-Val4–NH proton chemical shifts in CD3OH solution were in the order of IIa<IIbIIb>IIc. This order of β-turn preferences coincides with the order of the magnitudes of the Cotton effects in the CD spectra of the chromophoric derivatives, N-(2,4-dinitrophenyl)tetrapeptide p-nitroanilides, having the same sequences. This agreement supports the validity of the chiroptical method to study turn tendency of tetrapeptide sequences using chromophoric derivatives reported previously.
Studies on the Mechanism of Zeolite X Crystallization. I. Effects of Silica Sources of Starting Materials on the Crystallization of Zeolite X
Authors: Hino Ryozi , Matuura Ryohei , Toki Kenzi
Published: July 2006

The crystallization mechanism for zeolite was investigated. Tetraethyl orthosilicate and silica sol were used as silica sources. Many kinds of solid phases were obtained at various reaction times. These solid phases were characterized by analyses for chemical compositions, X-ray diffraction, adsorption of nitrogen gas and water vapor, and IR spectroscopy. The results obtained suggest that the solid phase derived from tetraethyl orthosilicate at an early stage of reaction is composed of slightly ordered skeletons. In addition, during aging of gel at room temperature, the structure of the solid phase of gel undergoes a rearrangement to form a crystalline structure. On the other hand, the gel phase obtained from silica sol is predominantly made up by the coagulation of disordered aluminosilicate polymers or silicic polymers. These gel phases act as a precursor, and a part of the gel dissolved into the liquid phase and the dissolved species are converted into crystals in the liquid phase. Thus, the silica sources influence the structure of gel and crystals. In general, the crystallization mechanism is strongly influenced by the starting materials, especially by the silica sources.
Penetration of Lysine–Leucine Copolymers into Lecithin Monolayers from Underlying Aqueous Solutions
Authors: Nakagaki Masayuki , Okamura Emiko , Kubota Shigeo
Published: July 2006

The penetration of water soluble polymers into lecithin monolayers was investigated for the random copolymers of l-lysine and l-leucine at various compositions in order to discuss the effect of hydrophobicity and charge density of the copolymers on their interaction with lipid monolayers. Compared to the penetration of the amino acids(l-lysine and l-leucine), the copolymer penetrated at very low concentration whereas the monomer (amino acid) did not. The amount of copolymer penetration increased significantly when the leucine fraction of a copolymer, XLeu, was larger than 0.3, while little penetration occurred when XLeu was smaller than 0.25. From these facts, it has been concluded that the penetration of lysine–leucine copolymers was not only attributed to the hydrophobicity or the charge density of copolymer molecules, but also to specific surface effects such as (1) the enhanced penetration of macromolecules by the preceded penetration of polymer segments of the same molecule, or (2) the formation of a compact α-helical structure as the result of the restricted motion of the segment near the lipid surface.
A Chromatographic Study of the Acidic Hydrolysis of cyclo-Hexa- and cyclo-Octaphosphate
Authors: Kura Genichiro
Published: July 2006

The hydrolysis rate of inorganic cyclo-hexa- and cyclo-octaphosphate in 0.1 mol dm−3 HCl was determined by means of anion-exchange chromatography. The phosphorus content in the column effluent was determined automatically by the use of the MoV–MoVI reagent. The hydrolysis reactions were first-order. The rate constant decreases from cyclo- tri- to cyclo-hexaphosphate with the increased ring, however, that of cyclo-octaphosphate increases again. This increase is thought to be due to the stronger proton affinity of cyclo-octaphosphate. The Arrhenius activation energies for cyclo-hexa- and cyclo-octaphosphate hydrolysis were 91.5 and 96.9 kJ mol−1 respectively.
Studies of the Selective O-Alkylation and Dealkylation of Flavonoids. VI. Demethylation of 8-Hydroxy-5,7-dimethoxyflavones with Anhydrous Aluminum Chloride or Bromide in Acetonitrile
Authors: Horie Tokunaru , Kourai Hiroki , Fujita Nobuhisa
Published: July 2006

The demethylation of seven 8-hydroxy-5,7-dimethoxyflavones with anhydrous aluminum chloride or bromide in acetonitrile was studied and the following results were obtained. (1) Anhydrous aluminum chloride in acetonitrile selectively split the 5-methoxyl group without cleavage of the 7-methoxyl group, and seven 5,8-dihydroxy-7-methoxy-flavones were quantitatively synthesized by the demethylation. (2) In the demethylation with anhydrous aluminum bromide, the 5- and 7-methoxyl groups on 4′,5,7-trimethoxy- and 3′,4′,5,7-tetramethoxy-8-hydroxyflavone were selectively split to give the corresponding 5,7,8-trihydroxyflavones in good yield. However, the demethylation was not accessible to the synthesis of 5,7,8-trihydroxy-3′,4′,5′-trimethoxyflavone, 4′,5,7,8-tetrahydroxy-3′-methoxy-, and 3′,5,7,8-tetrahydroxy-4′-methoxyflavone, because of the cleavage of the methoxyl groups on the B ring. The synthesized flavones were employed for the identification of the two natural flavones, which were proposed to be 4′,5,8-trihydroxy-7-methoxyflavone and 4′,5,8-trihydroxy-3′,7-dimethoxyflavone. The former, salvitin, was revised to 4′,5,7-trihydroxy-6-methoxyflavone and the latter seemed to be 4′,5,7-trihydroxy-3′,8-dimethoxyflavone.
Studies of Peptide Antibiotics. XLV. Syntheses of Gramicidin S-like Analogs with Macro-ring Structures
Authors: Ando Setsuko , Takiguchi Hideo , Izumiya Nobuo
Published: July 2006

Three cyclic tetradecapeptides related to gramicidin S (GS): cyclo(–Leu–Orn–Leu–Orn–Leu–d-Phe–Pro-)2, cyclo(–Leu–Orn–Leu–Orn–Leu–d-Phe–Sar–)2, and cyclo(–Leu–Orn–Leu–Orn–Leu–d-Phe–Gly–)2, were synthesized to investigate the contributions of the ring size of cyclic peptides and of the number of the basic amino acid residues to the antibacterial activity. The protected cyclic tetradecapeptides were synthesized through a cyclization reaction of the linear tetradecapeptide azide in pyridine. Hydrogenolysis of the protected cyclic peptides afforded crystalline tetrahydrochlorides of the analogs. The homogeneity of the analogs was ascertained by TLC, paper electrophoresis, and elemental analysis. In the experiment of circular dichroism, the two analogs with 7,7′-Pro or 7,7′-Sar gave spectra similar in shape to that of GS, while the analog with 7,7′-Sar gave a slightly different spectrum from that of GS. The antibacterial assays showed that the analog with 7,7′-Pro exhibited considerable activities against the microorganisms tested, particularly against Gram-negative bacterias such as Escherichia coli and Shigella sonnei. On the other hand, the analogs with 7,7′-Sar or 7,7′-Gly exhibited weaker activities than that of GS.
Mechanisms of Singlet and Triplet Sensitized Decomposition of Bis(2-phenylbenzoyl) Peroxide
Authors: Kitamura Akihide , Tanikawa Hiroharu , Oohashi Kunio , Sakuragi Hirochika , Tokumaru Katsumi
Published: July 2006

Bis(2-phenylbenzoyl) peroxide (2-PhBPO) was found to decompose on singlet and triplet sensitized irradiations in benzene and carbon tetrachloride. The quantum yields were determined to be 0.48 and 0.43 on direct excitation and chrysene sensitization in benzene, respectively, and 0.62 and 0.60 on benzophenone and 3′-methoxyacetophenone sensitizations in carbon tetrachloride, respectively. The reaction mechanisms are discussed from the standpoint of the modes of bond cleavage.
Effects of Lysine and Arginine Derivatives on the Base Stacking Association of 2′-Deoxyguanosine 5′-Monophosphate
Authors: Hirota Kazumi , Igarashi Mitsuru , Inoue Yoshio , Chûjô Riichirô
Published: July 2006

The effects of basic amino acid residues on the base stacking of nucleotides have been studied to clarify the nature of interaction between histones and DNA′s. For this purpose, lysine and arginine derivatives were used as models for basic amino acid residues in histone. The base stacking association of 2′-deoxyguanosine 5′-monophosphate(5′-dGMP) in aqueous solution has been studied by the measurement of the concentration dependence of 1H NMR chemical shifts of 5′-dGMP both in the absence and in the presence of the basic amino acid derivatives at different pH’s. We clarified that the lysine favors the base stacking association of 5′-dGMP through the interaction with the phosphate group(s), while an excess of the arginine destabilizes the stacking aggregates through the interaction with the base moiety. We also clarified that the ionization of the phosphate group destabilizes the stacking association of 5′-dGMP both in the absence and in the presence of the basic amino acids.
Studies on Salt Hydrates for Latent Heat Storage. IV. Crystallization in the Binary System CH3CO2Na–H2O
Authors: Wada Takahiro , Kimura Fumiko , Matsuo Yoshihiro
Published: July 2006

In the binary system CH3CO2Na–H2O, crystallization temperature on slow cooling from a melt, glass transition temperature and crystallization temperature on slow heating from a quenched vitrified solid were measured by varying the CH3CO2Na concentration. The crystallization behaviour in the binary system CH3CO2Na–H2O is characterized as follows; (1) crystallization region of ice extends into the CH3CO2Na-rich side from the eutectic composition, (2) a hard crystallization region exists in the composition between CH3CO2Na 35wt% and 40wt%, (3) the crystallization temperature range of CH3CO2Na·3H2O is from −50 °C to −30 °C and very narrow.
Laser Flash Photolysis of Benzene. VI. Photolysis in Aqueous Solution
Authors: Shimo Nobuo , Nakashima Nobuaki , Yoshihara Keitaro
Published: July 2006

Three transient absorption spectra in aqueous solution were observed by irradiation of benzene with an excimer laser (KrF, 248 nm or ArF, 193 nm). A short-lived absorption with a peak at 275 nm is assigned to the Sn←S1 absorption. A long-lived absorption, which appears as a clear shoulder at 230 nm, stays longer than 500 ns and is not shortened by oxygen. This species is tentatively assigned to benzvalene, and the quantum yield is determined to be ca. 0.1. Solvated electron with a peak at 720 nm was formed via multiphoton processes at a power level of 60 mJ/cm2 of an ArF laser. The Tn←T1 absorption was lower than our detection limit (ΦT<0.1).
Electronic Spectra and Crystal Structure of Organic Radical Salt: Dimethyldibenzotetrathiafulvalenium Tetrafluoroborate
Authors: Tanaka Chizuko , Tanaka Jiro , Dietz Karlheinz , Katayama Chuji , Tanaka Masashi
Published: July 2006

The single crystal of dimethyldibenzotetrathiafulvalenium tetrafluoroborate (1 : 1) has been prepared by electrocrystallization. The crystal structure has been determined by X-ray crystal analysis. The salt crystallizes in Ibam with a=14.637(3), b=17.625(6), c=13.614(3) Å. The radical cations align along the c axis at nearly equal spacing forming eclipsed dimers and the dimeric units are stacked with a staggered mode. The electronic spectra of the radical cation and the dimer have been measured in solution and the assignment has been presented with an aid of the MO calculation by Pariser-Parr-Pople method. A charge transfer (CT) band observed in the dimer has been correlated with the charge resonance of unpaired electron between the HOMOs of the radical cations. Polarized reflection spectra of single crystal have been measured with three different crystal planes and the assignment of both the CT and molecular type bands have been confirmed with polarization measurement. The energy and the intensity of the CT band indicate that the unpaired electron is localized on each radical, but the CT configuration is involved significantly. The crystal is an insulator as is expected from the electronic structure; the large U, which is evidenced by the energy of the CT band, and the staggered packing hinders electronic conduction. It implies that a monovalent radical salt is difficult to be metallic unless a mixed valence state is involved.
The Synthesis and Decomposition of Calcium Bis(hydrogenphosphoramidate)
Authors: Watanabe Makoto , Inagaki Toshihiko , Sato Shoji
Published: July 2006

Calcium bis(hydrogenphosphoramidate)–water (2/3) was made by adding an aqueous calcium chloride solution to an aqueous potassium hydrogenphosphoramidate solution. The product decomposed slowly to diammonium calcium diphosphate monohydrate in air at room temperature. When the product was heated above 600 °C, the decomposition product was β-type calcium metaphosphate. According to the result of the isothermal decomposition of the product at 150 °C in air, no formation of P–NH–P linkages by the elimination of NH3 from P–NH2 linkages was observed, and it was concluded that the phosphoramidate thermally decomposed to form only polyphosphates in air.
The Autoxidation of 2,3-Dihydroxy-2-propenal (Triose Reductone). The Effects of the pH on the Rate Constants
Authors: Abe Yasuo , Horii Hideo , Taniguchi Setsuo , Kamai Kazuo , Takagi Masanosuke
Published: July 2006

The autoxidation of 2,3-dihydroxy-2-propenal (triose reductone) was investigated between pH 2.83 and 13.91 in the presence of disodium dihydrogen ethylenediaminetetraacetate (EDTA 2NA). The reaction obeyed the first-order rate law with respect to the triose reductone and the zeroth-order rate law with respect to oxygen when the oxygen concentration was higher than 0.246 mM (1 mM=10−3 mol dm−3) at 30 °C. The pH dependence of the reaction rates showed that the reaction rates are governed by the acid-base equilibrium of triose reductone. The rate constants for neutral and singly- and doubly-charged anions of triose reductone at 30 °C were (3.6±0.1)×10−6, (7±1)×10−5, and (1.8±0.1)×10−2 s−1 respectively. The hydrogen peroxide produced as a result of the triose reductone oxidation was also found to oxidize triose reductone.
Highly Stereoselective Isomerization of Monosubstituted 1-Alkenes to (E)-2-Alkenes by Catalysis of (C5Me5)2TiCl2/NaC10H8
Authors: Akita Munetaka , Yasuda Hajime , Nagasuna Kinya , Nakamura Akira
Published: July 2006

The catalyst systems which consist of MCl2(C5R5)2(M=Ti, Zr; R=H, CH3)/NaC10H8, i-C3H7MgBr, n-C4H9Li or LiAlH4 in 1 : 2 ratio were highly effective for the stereoselective isomerization of monosubstituted 1-alkenes to (E)-2-alkenes. Unconjugated dienes were converted to (E)- or (E,E)-dienes. The catalysis of (C5Me5)TiCl2/NaC10H8 was extremely high and resulted in the complete isomerization of 1-alkenes in >99% stereoselectivity within a short period. The use of the bulky C5Me5 ligand is essential to find out the excellent stereoselectivity. Systems, (C5H5)2TiCl2/NaC10H8 and (C5H5)2TiCl2/i-C3H7MgBr showed less selectivity and the catalysis of the corresponding zirconium systems was very poor irrespective of the reducing agents and substrates.
Proton-driven Ion Transport and Metal-assisted Amino Acid Transport with an Anion-capped Azacrown Ether
Authors: Shinkai Seiji , Kinda Hidefumi , Araragi Yoshikazu , Manabe Osamu
Published: July 2006

We have found that 1,10-diaza-4,7,13,16-tetraoxa-18-crown-6 with a carboxylate cap and a hydrophobic dodecanoyl group (1) acts as a new class of ion carrier for membrane transport. The rate of K+ transport across a chloroform liquid membrane was significantly affected by pH of the OUT aqueous phase: The rate decreased with increasing or decreasing pH, providing a maximum at around pH 5. The main species of 1 in the neutral pH region should be zwitterionic 1±, so that one may rationalize the pH-rate profile in terms of (i) “enforced ion release” due to protonation of the ring nitrogen and (ii) high lipophilic nature of zwitterionic 1±. The efficiency of 1 was further demonstrated by active K+ transport from the basic IN aqueous phase to the neutral OUT aqueous phase. Also, 1 was capable of carrying amino acids in the presence of alkaline earth metal cations. These results suggest that, being different from conventional anion-capped crown ethers, the aza crown ethers carrying the N-substituted carboxylate cap exhibit a new class of ionophore functions.
Facile Synthesis of Cyclic Dipeptides and Detection of Racemization
Authors: Ueda Toshihisa , Saito Morinobu , Kato Tetsuo , Izumiya Nobuo
Published: July 2006

Several cyclic dipeptides were synthesized by refluxing methanolic solution of dipeptide methyl esters in high yield and purity. Cyclic dipeptides prepared by the Fischer method, the Nitecki method, and the present methanol-reflux method were compared with respect to yield and optical purity. The methanol-reflux method usually gave good results. High-performance liquid chromatography was effectively applied to detect racemization.
The Mechanism of the Reaction of (Aryloxy)trimethylstannane with Methanesulfonyl Chloride. Solvent and Substituent Effects on the Rate of the Reaction
Authors: Kozuka Seizi , Yamaguchi Shigeru , Tagaki Waichiro
Published: July 2006

A kinetic study has been conducted on the reactions of (aryloxy)trimethylstannanes with methanesulfonyl chloride giving chlorotrimethylstannane and aryl methanesulfonates. The reaction was found to obey a second order kinetic equation. The solvent effect on the rate of the reaction appeared obscure although a small rate enhancement was observed in a polar solvent. Substituent effect of the aryloxyl group was found to be dependent on the solvent used while a clear isokinetic relationship was observed. A charge separated four-center transition state has been suggested for the reaction.
Effect of the Polydispersity of Molecular Length on the Decay Process of Transient Electric Birefringence of Rodlike Macromolecules in Dilute Solution
Authors: Yamaoka Kiwamu , Fukudome Kiyohiro
Published: July 2006

The effect of polydispersity on transient electric birefringence (EB) was examined for a dilute solution which contains like macromolecules of varying lengths. The molecules were assumed to be rigid rods of cylindrical symmetry, so that the molecular weight is linearly proportional to length. Polydispersity was expressed by the ratio of the weight-average to the number-average lengths lw/ln. A logarithmic-normal type continuous length distribution was generally used. Calculations were performed for the birefringence-average relaxation time 〈τ〉EB and initial slope 〈S〉EB as a function of the electric field strength E, which is applied prior to the start of the decay process, with the electric parameter (βw)2/2γw, which is related to the weight-average permanent dipole moment (the βw-term) and polarizability anisotropy (the γw-term). Both 〈τ〉EB and 〈S〉EB are very sensitive to E, lw/ln, and (βw)2/2γw. A convenient method was devised for determining the polydispersity parameters (lw/ln and lw) from the weight-averages of relaxation time and initial slope, which are free from the mechanism of field orientation. Examples are given for a polydisperse, rigid rodlike sonicated DNA sample in aqueous solution.
Esterification of Aromatic Carboxylic Acids with Alcohols Using 2-Chloro-3,5-dinitropyridine as a Condensing Agent
Authors: Takimoto Seiji , Abe Naomi , Kodera Yasushi , Ohta Hiroshi
Published: July 2006

The reaction of 2-chloro-3,5-dinitropyridine (CDNP) with carboxylic acids and alcohols was examined, and it was found that CDNP was a useful condensing agent. Various esters were prepared in good yields.
Cyanation of 1-Halocycloalkenes Catalyzed by Tetracyanocobaltate(I). Convenient Synthesis of 1-Cyanocycloalkenes
Authors: Funabiki Takuzo , Kishi Hirohito , Sato Yoshihiro , Yoshida Satohiro
Published: July 2006

1-Cyanocycloalkenes (1-cyanocyclopentene, -hexene, -heptene, and -octene) were readily synthesized by catalytic cyanation of the corresponding 1-halocycloalkenes with tetracyanocobaltate(I). Reactivities of methyl-substituted 1-chlorocyclohexenes were lower than that of 1-chlorocyclohexene, and 1-chloro-2-methylcyclohexene scarecely reacted. Hydrogenation and isomerization of 1-cyanocycloalkenes were observed only with 1-cyanocycloheptene and 1-cyano-6-methylcyclohexene, respectively.
Studies of Aromatic Sesquiterpenes. IV. The Synthesis of γ-Calacorene, Calamenene, and 4-Methoxyisocadaiene
Authors: Adachi Kazuo , Mori Masahito
Published: July 2006

The Grignard reaction of 3,4-dihydro-4,7-dimethyl-1(2H)-naphthalenone with isopropylmagnesium bromide gave a 3 : 1 mixture of normal reaction product and α-isopropylidene ketone, from which, the title sesquiterpenes and 1,2-bis(3-isopropyl-4-methoxy-6-methyl-1-naphthyl)ethane were synthesized.
Infrared and Visible Absorption Spectra of Doped (CH)x, (CD)x, and Copolymers [(C2H2)1−y(C2D2)y]x
Authors: Fujimoto Hitoshi , Tanaka Masashi , Tanaka Jiro
Published: July 2006

Infrared and visible absorption spectra of (CH)x, (CD)x, and the copolymers [(C2H2)1−y(C2D2)y]x doped with Br2 or I2 were measured for various values of y between 0 and 1. By the doping, the π→π* band located in the 19000 cm−1 region disappeared while several new bands were observed at 800–900-, 1000–1400-, and 5000-cm−1 regions. The absorption band shapes and the locations of the 5000- and 19000-cm−1 bands did not depend appreciably upon the value of y. The charged soliton induced vibrational bands were found at 870-and 1370-cm−1 in (CH)x and 1230-, 1100-, and 780-cm−1 in (CD)x. In addition, another new bands were found around 570–660 cm−1 region by decreasing the temperature of the doped film to 160 K. These new bands were not shifted by the isotopic substitution. A plausible mechanism for the appearance of this band is suggested as an oscillation of trapped charged soliton around the negatively charged dopant. For the heavily doped (CH)x film, the gapless transition was observed and the optical conductivity was estimated by the Drude formula and was compared with the value obtained by a direct conductivity measurement.
Sodium Isotopic Exchange Rate between Disodium Zirconium(IV) Bis(orthophosphate) Trihydrate and Aqueous Solutions
Authors: Inoue Yasushi , Yamada Yoshimune
Published: July 2006

The sodium isotopic exchange rate between the large crystals of disodium zirconium(IV) bis(orthophosphate) trihydrate and aqueous solutions was determined radiochemically. The exchange proceeded quickly up to 5% of the total, followed by a slow process. The first step was attributed to the instantaneous attainment of the equilibrium between the imperfect surface layers of the crystals and the solution, and the second step was found to be controlled by the diffusion of sodium ions along the direction perpendicular to the layers consisting of zirconium atoms. The diffusion constant, D, was calculated with the equation obtained by Fick’s diffusion law under the conditions of slab geometry and infinite solution volume. From the dependence of D on temperature, the activation energy for the diffusion was evaluated to be 101 kJ mol−1.
Electrocatalytic Reduction Using Raney Nickel
Authors: Chiba Toshiro , Okimoto Mitsuhiro , Nagai Hiroshi , Takata Yoshiyuki
Published: July 2006

The Raney nickel catalyst was employed as a catalytic electrode in the electrohydrogenation of various unsaturated compounds, including ketones, aromatic aldehydes, Schiff’s bases, oximes, nitriles, aromatic nitro compounds, olefins, and acetylenes. The hydrogen generated electrochemically was adsorbed and activated at the surface of the catalyst; it effectively hydrogenated these compounds, affording products which are very similar to those obtained in a normal catalytic hydrogenation with Raney nickel.
Convenient Preparation of Dimethyl (Trifluoromethyl)malonate and Related Compounds
Authors: Ishikawa Nobuo , Yokozawa Tsutomu
Published: July 2006

The preparative method for dimethyl (trifluoromethyl)malonate (4) from the adduct of perfluoro-2-methylpropene with methanol was improved, and several reactions of this base-sensitive substance were investigated. Alkylation of 4 was achieved by using CsF as a condensing agent, and the Michael addition on vinyl ketones proceeded in triethylamine–pyridine medium.
Lanthanoid Nitrate Complexes with Some Polyethylene Glycols and Glymes
Authors: Hirashima Yoshiyuki , Kanetsuki Koji , Yonezu Ikuo , Kamakura Kiyohito , Shiokawa Jiro
Published: July 2006

Lanthanoid nitrates (Ln(NO3)3) formed solid complexes with several polyethylene glycols and glymes. The compositions of the complexes were 1:1 (Ln:ligand) for triethylene glycol(EO3), tetraethylene glycol(EO4), pentaethylene glycol(EO5), and tetraglyme, 1:2 (Ln:ligand) for diethylene glycol, 2:1 for heptaethylene glycol, and 4:3 for pentaglyme and hexaglyme. Solid complexes were deposited also for hexaethylene glycol, but their compositions were not definitely determined. The solid complexes obtained here were all deliquescent. The deposition of the complexes was generally interfered with by water in the solution, and was not observed for some heavier lanthanoids when a small amount of water was present in the solution. The solubilities of the solid complexes with EO4 and EO5 increased with an increase in the atomic number of the lanthanoid, a fact suggesting a unique selectivity of the glycols. The infrared absorption bands of polyethylene glycols or glymes in the 1000–1150 cm−1 region became sharper upon the complexing of the glycols or glymes with lanthanoids; this sharpening can be explained by the change in the conformations in the ligand molecules.
The Adsorption of Tetramethylurea at the Mercury/Water Interface
Authors: Ikeda Osamu , Jimbo Hiroyuki , Tamura Hideo
Published: July 2006

The adsorption of tetramethylurea (TMU) at the mercury/water interface was studied by means of differential capacity measurements. TMU was found to take three different orientations, depending on the surface excess and the charge sign of the electrode. These orientations could not be explained simply by the orientation of the TMU dipole in the electric field or by the hydrophobic interaction between the methyl groups of TMU and the electrode, but it was explained on the basis of interactions between TMU and water molecules, and on the basis of the TMU molecules themselves in the adsorption layer and an electronic polarization effect of the nitrogen atoms in TMU. A few water-adsorption models were compared in an attempt to estimate the dipole moment of the TMU molecule at the interface.
Synthesis and Characterization of a New Family of Binuclear Nickel(II) Complexes with a Terephthaloyl or Isophthaloyl Bridge
Authors: Matsumoto Naohide , Hirano Akira , Ohyoshi Akira
Published: July 2006

A new family of binuclear nickel(II) complexes with a terephthaloyl or isophthaloyl bridge have been prepared by the electrophilic substitution reaction of (11,13-dimethyl-1,4,7,10-tetraaza-10,12-cyclotridecadienato)nickel(II) (Ni(Me2[13]dienatoN4)]+) or (12,14-dimethyl-1,4,8,11-tetraaza-11,13-cyclotetradecadienato)nickel(II) ([Ni(Me2[14]dienatoN4)]+) containing a nucleophilic center at the γ-carbon and terephthaloyl chloride or isophthaloyl chloride. The complexes were characterized by elemental analyses, infrared spectra, 1H NMR spectra, electronic spectra, and conductivity measurements.
Dependence of Electric Polarizability of Rodlike DNA in Aqueous Solutions on Ionic Strength as Studied by Electric Dichroism and Birefringence. A Comparison between Experimental and Theoretical Results
Authors: Yamaoka Kiwamu , Matsuda Koichiro , Takarada Kaoru
Published: July 2006

Orientation of a sonicated DNA fragment in aqueous solutions containing sodium chloride (0.2–4 mmol/dm3) by an external electric field was discussed in terms of counterion-induced electric moments by using the electric dichroism and birefringence data experimentally determined at limiting low field strengths.
Thermodynamic Study on Solvent Extraction of Sodium and Potassium Picrates by Benzo-15-crown-5
Authors: Takeda Yasuyuki
Published: July 2006

In order to obtain enthalpy and entropy changes for extraction of sodium and potassium picrates by benzo-15-crown-5 (B15C5) between benzene and water, the overall extraction equilibrium constants for the 1:1:1 complexes of B15C5 with the salts were determined at various temperatures. The enthalpy and entropy changes for both the systems are all large and negative.
Photoinduced Alcoholysis of Trihaloacetyl Group
Authors: Izawa Yasuji , Ishiguro Katsuhiro , Tomioka Hideo
Published: July 2006

Photolysis of trichloroacetamide in nondegassed methanol gave methyl oxanilate (13–44%), along with carbamate (3–20%) and amine (4–12%). Similar irradiation of other trichloroacetyl derivatives of aliphatic ketone, aldehyde, and acetate afforded only radical product. The results are interpreted in terms of the mechanism involving electron transfer of the radical pair.
Benzocyclobutenes Part 8. Geometrical Isomerism of Arylhydrazones of Benzocyclobutene-1,2-dione
Authors: Cracknell Mark Edward , Goodland Michael Charles , McOmie John Frederick William
Published: July 2006

Four mono(arylhydrazone)s of benzocyclobutene-1,2-dione (BBD) have been prepared in which the aryl group is 2,4-dinitrophenyl, 4-bromophenyl, phenyl, and 4-nitrophenyl. The first three have been separated into their E- and Z-isomers whose configurations are assigned on the basis of spectra and Rf values. Improvements in the preparation of BBD from 1,2-dibromo-1,2-dihydrobenzocyclobutene are described.
Reaction of α,α-Bis(trimethylsilyl)phenylthiomethyllithium with (Chloromethyl)oxiranes. Synthesis of 1-Alkyl-3-phenylthio-3-trimethylsilyl-1-trimethylsiloxycyclobutanes
Authors: Takeda Takeshi , Naito Satoru , Ando Kazuo , Fujiwara Tooru
Published: July 2006

The cyclobutanes of the title are produced in good yields by means of the reaction of the title.
Electrochemical Properties of Electrochemically Polymerized Polypyrrole Film in the Dark and under Light Irradiation
Authors: Inoue Tooru , Yamase Toshihiro
Published: July 2006

Polypyrrole films prepared on Pt or SnO2 through electrochemical oxidative polymerization of pyrrole were characterized with respect to electroconductivity by photoelectrochemical measurements. Redox reactions of solution species such as methyl viologen, hydroquinone, oxygen, Cu2+, I−, and Br− occur on these electroconductive films. Light excitation of the film with wavelengths shorter than 550 nm results in observable cathodic photocurrent at the potential region more negative than 0.0 V vs. Ag. The polypyrrole film is a p-type semiconductor with a bandgap energy of ca. 2.2 eV and is stable during redox reactions.
Studies of Bitter Peptides from Casein Hydrolyzate. VII. Bitterness of the retro-BPIa (Val–Ile–Phe–Pro–Pro–Gly–Arg) and Its Fragments
Authors: Shigenaga Toshiaki , Otagiri Ken , Kanehisa Hidenori , Okai Hideo
Published: July 2006

To explain the bitter taste exhibited by BPIa (Arg–Gly–Pro–Pro–Phe–Ile–Val) which was isolated from casein hydrolyzate, we have proposed the following requirement: its characteristic spatial structure: the basic moiety in the N-terminal and the hydrophobic moiety in the C-terminal were affected to each other by prolylprolyl residue, is necessary for the bitterness to be exhibited. As for BPIc (Val–Tyr–Pro–Phe–Pro–Pro–Gly–Ile–Asn-His), which is the other fraction, although it exhibited as strong and bitter a taste as BPIa, the basic moiety of BPIc is located in the C-terminal and its hydrophobic moiety is located in the N-terminal. The authors synthesized retro-BPIa with the reverse peptide sequence and its fragments. The retro-BPIa exhibited as strong and bitter a taste as BPIa. However, the bitterness of the fragments of retro-BPIa was far weaker than that of retro-BPIa.
A DNMR Study of Restricted Methylene Rotation in 2-Pyridylmethyl- and 3-Methyl-2-pyridylmethyllithium
Authors: Matsui Hideki , Yoshino Akihiro , Yoshida Tadayoshi , Takahashi Kensuke
Published: July 2006

Thermodynamical parameters for the restricted rotation of the title carbanions have been obtained by means of the DNMR techniques. The activation energies and entropies thus obtained are about 93 kJ mol−1 and 95 J K−1 mol−1 for the two carbanions studied; these values are larger than those of the similar rotations observed in arylmethanide ions. The methylene rotation is thus extremely hindered in these carbanions.
Palladium(II)-Catalyzed Acetoxylation and Chlorination of 2-Alkenyl p-Tolyl Sulfones
Authors: Ogura Katsuyuki , Shibuya Nobuhiro , Takahashi Kazumasa , Iida Hirotada
Published: July 2006

2-Alkenyl p-tolyl sulfones were converted into the corresponding 3-acetoxy(or chloro)-1-alkenyl p-tolyl sulfones via π-allylpalladium complexes which reacted regiospecifically with a nucleophile such as acetate anion or chloride anion in the presence of Cu(II).
Bis(trimethylsilyl) Sulfate Catalysis in γ-Lactonization of Cyclopropanecarboxylates Activated by Carbonyl Substituents on α-Carbon
Authors: Morizawa Yoshitomi , Hiyama Tamejiro , Oshima Koichiro , Nozaki Hitosi
Published: July 2006

The title reaction of 1-carbonyl substituted cyclopropanecarboxylates proceeds under C(1)–C(2) bond cleavage to produce γ-lactones. Stereochemically, the reaction takes two pathways: (1) substrates with a cationstabilizing group like vinyl on C(2) give thermodynamically favored γ-lactones having the thermodynamically more stable arrangement of substituents irrespective of the configuration of the cyclopropane substrates, (2) substrates without such a cation-stabilizing group afford γ-lactones under ca. 70% inversion at C(2) reaction center.
Cycloaddition Reactions of Heteroaromatic Thioketones with Maleic Anhydride, Norbornene, Acrylonitrile, Styrene, and 2-Chloroacrylonitrile
Authors: Ohmura Haruo , Motoki Shinichi
Published: July 2006

Heteroaromatic thioketones react with maleic anhydride, norbornene, acrylonitrile, and styrene to form the Diels-Alder adducts, respectively. The thioketones also undergo cycloaddition with 2-chloroacrylonitrile followed by elimination of hydrogen chloride to give heteroaromatic analogues of o-quinodimethan derivatives. In these reactions, the thioketones act as a heterodiene on the dienophiles to give [4+2]cycloadducts regioselectively.
Freezing of Water as Aggregated with Cationic Surfactants in Deuterochloroform
Authors: Sunamoto Junzo , Hamada Tomiko , Kondo Hiroki
Published: July 2006

Freezing of water solubilized with the cationic CTAX(hexadecyltrimethylammonium halides) and QDX (dihexadecyldimethylammonium halides) in deuterochloroform was observed by 1H-NMR method. The freezing of water was largely affected by the characteristics of the water-surfactant aggregates by the R-value(=[H2O]/[surfactant]) and the structure of surfactant. In the 0.20 M (1 M=1 mol dm−3) CTABr/0.16 M H2O/CDCl3 system, for example, the apparent freezing was observed at about −20 °C.
Thermal Decomposition of t-Butyl Heptafluoroperoxybutyrate
Authors: Sawada Hideo , Hagii Hidehiko , Aoshima Kazuyoshi , Arai Takeshi
Published: July 2006

The decomposition of t-butyl heptafluoroperoxybutyrate (TBH) was studied in both toluene and methanol. Kinetic and product studies from the thermolysis showed that this peroxy ester decomposes heterolytically in nonpolar solvents like toluene with homolysis, whereas in methanol this peroxy ester undergoes principally transesterification.
Reaction Efficiency of Exciplexes in Singlet Sensitized Decomposition of Dibenzoyl Peroxide
Authors: Misawa Hiroaki , Kitamura Akihide , Sakuragi Hirochika , Tokumaru Katsumi
Published: July 2006

Quantum yields were measured for aromatic hydrocarbon-sensitized decomposition of dibenzoyl peroxide in benzene. For the sensitizers employed, naphthalene, phenanthrene, triphenylene, and chrysene, the ratio of the rate constants for decay and radical formation from intermediate exciplexes was found to be similar (0.2–0.4), indicating that the reactivity of the peroxide moiety in the intermediate is independent of the structural factors of the sensitizers as far as examined.
On the Penetration Rate and the Role of Acids in the Control of Impregnation Profiles
Authors: Komiyama Masaharu , Merrill Robert P
Published: July 2006

Two factors which play important roles in determining the concentration profiles in the impregnation of porous catalysts, viz., penetration rate of impregnating solution and the use of acids, were examined. The flow rate of impregnating solution into a spherical dry pellet consisting of polydispersed pores obeyed the equation which assumed constant pressure differential at the liquid front independent of its position in the pellet. The adsorption behavior of nickel ions onto γ-alumina strongly depended on the pH of the solution, and very weakly on the kind of acids used. By controlling the pH of the impregnating solution, it was possible to obtain a surface impregnation, a uniform impregnation and a subsurface impregnation for nickel on γ-alumina.
Infrared Spectroscopic Studies on the Resilium of a Surf Clam, Spisula (Pseudocardium) sachalinensis
Authors: Kikuchi Yasuo , Tamiya Nobuo
Published: July 2006

Sulfinyl group was detected in the resilium (internal hinge-ligament) of surf clam by IR spectrometry. The results reconfirm the previous reports on the presence of methionine S-oxide in the intact resilium protein. Aragonite structure was deduced for CaCO3 in the resilium because the IR spectrum of the resilium was reproduced from those of decalcified resilium and aragonite (CaCO3). The IR spectrum of intact protein component in the resilium was simulated from those of the resilium and aragonite (CaCO3).
Isolation and Assignment of Two Isomers of trans(NO2)-Dinitrobis[(S)-2-aminomethylpyrrolidine]cobalt(III) Perchlorate
Authors: Saburi Masahiko , Yokowo Yasuhiko , Yoshikawa Sadao
Published: July 2006

Two possible isomers (trans,cis and trans,trans) of trans-(NO2)-[(Co(NO2)2(ampr)2]ClO4 (ampr=(S)-2-aminomethylpyrrolidine) were isolated separately by fractional recrystallization. The dinitro complexes were converted to the corresponding trans(Cl,NO2)–[CoCl(NO2)(ampr)2]+ complexes. Based on the circular dichroism and 13C-NMR spectral data, it was shown that the less soluble dinitro complex gave the single isomer of the chloronitro complex, while the more soluble one yielded two diastereomeric chloronitro complexes. Thus, the former is assigned to the trans,cis configuration, and the latter to the trans,trans, taking the geometries of the complexes into consideration.
The Preparation of Dl-Isoleucine by Asymmetric Transformation
Authors: Hongo Chikara , Yoshioka Ryuzo , Tohyama Masanori , Yamada Shigeki , Chibata Ichiro
Published: July 2006

The chemical synthesis of isoleucine leads to a mixture of Dl-isoleucine and Dl-alloisoleucine. The preparation of Dl-isoleucine from the mixture was studied. When the mixture was reacted with 1,5-naphthalenedisulfonic acid in water, Dl-isoleucine formed the less soluble 1,5-naphthalenedisulfonate and could be separated in the form of the salt from the mixture. The soluble Dl-alloisoleucine salt was easily epimerized by heating in acetic acid in the presence of salicylaldehyde and free isoleucine mixture. Asymmetric transformation between the two diastereoisomeric racemates was carried out by the simultaneous combination of the fractional crystallization of the less soluble Dl-isoleucine salt and the epimerization of the soluble Dl-alloisoleucine salt. Dl-Isoleucine salt was obtained in a yield of up to 95% from a Dl-isoleucine–Dl-alloisoleucine mixture or even from Dl-alloisoleucine.
Sorption of Ammonia/Ammonium Ion on Crystalline Hydrous Titanium Dioxide Fibers
Authors: Sasaki Takayoshi , Komatsu Y\={u} , Fujiki Yoshinori
Published: July 2006

The sorption of ammonia/ammonium ion has been studied on crystalline hydrous titanium dioxide fibers with a layer structure, which are prepared from potassium tetratitanate (K2Ti4O9). From the measurement of the distribution coefficient, it was found that this material strongly preferred ammonium ion to sodium ion. The results of the pH titration curves indicated that this material showed a wide range of acidities toward ammonia/ammonium ion and had 2.63 mequiv/g of an apparent capacity which was about a half of the theoretical ion-exchange capacity. The characterizations of the ammonium adsorbed solid phase at various loading levels were carried out by measuring the X-ray powder diffractograms and the water contents. From these studies, it was concluded that the sorption-desorption reaction of ammonia/ammonium ion on this material took place almost reversibly in three stages.
Electronic Absorption, Magnetic Circular Dichroism, and Circular Dichroism Spectra of cis- and trans-[Pd(Cl)2(N)2]-type Complexes and Their Electronic Structures
Authors: Nakayama Kazuhiko , Komorita Takashi , Shimura Yoichi
Published: July 2006

The electronic absorption and MCD spectra of [PdCl2L] (L=ethylenediamine(en), 1,3-propanediamine, N,N-dimethylethylenediamine, N,N′-dimethylethylenediamine, N,N-diethylethylenediamine, and N,N-dimethyl-1,3-propanediamine) and trans-[PdCl2(L)2] (L=EtNH2, Me2NH, Me3N, n-BuNH2, i-BuNH2, s-BuNH2, t-BuNH2, and rac-pea (pea=1-phenylethylamine)), and CD spectra of [PdCl2L] (L=(S)-1,2-propanediamine-(S-pn) and (2S)-N1,N1-diethyl-1,2-propanediamine) and trans-[PdCl2(S-pea)2] have been measured over the visible-near UV region, together with the corresponding spectra of [PtCl2L] (L=en and S-pn). The examination of the three kinds of spectra as well as their Gaussian analyses indicates that the splitting pattern of metal d orbitals for the cis type complexes is similar to that for [PdCl4]2−, and that as to the trans complexes the dx2−y2←dxz and dyz transitions split largely to give apparent two spin-allowed d-d bands characteristic of the trans complexes. The average energy of the dx2−y2←dxz and dyz transitions for the trans complexes is approximately equal to the energy of the dx2−y2←dxz,yz (D4h) ones for the cis complexes. The transition energies of dx2−y2←dxy and dx2 do not differ largely between both types of complexes. The assignments of high-intensity bands have also been made tentatively.
Application of Gel Chromatography to Determining Formation Constants of Inclusion Compounds of Cyclodextrins
Authors: Sanemasa Isao , Mizoguchi Takemi , Deguchi Toshio
Published: July 2006

The gel filtration technique (Hummel and Dreyer method) was applied to determining formation constants of inclusion complexes of α- and β-cyclodextrins. As guest substances, p-nitrophenolate, p-nitrophenol, benzoate, and benzoic acid were used. Formation constants were determined at room temperature (25–30 °C) using Sephadex G-10 gel in aqueous buffered solutions of a constant ionic strength of 0.5 with NaCl or with phosphate buffer, and the results were compared with literature values. The method is applicable to such guest substances as exhibit strong adsorption onto the gel matrix.
Emergence of Nematic Phase in Purely Smectogenic Alkyl 4-(4-Substituted Benzylideneamino)benzoates by Chain Branching of the Ester Alkyl Group
Authors: Matsunaga Yoshio , Miyajima Nobuhiko
Published: July 2006

2-Methylation of the ester butyl and pentyl groups in the phenyl-substituted compounds and also of the ester propyl, butyl, and pentyl groups in a number of the alkoxy-substituted compounds resulted in the production of nematic liquid crystals.
Preparation and Characterization of the Diastereoisomers of the (S)- or (R)-1,2-Propanediaminebis(1,10-phenanthroline)cobalt(III) Ion
Authors: Tatehata Akira , Natsume Shigeru
Published: July 2006

Four diastereoisomers of the type [Co(S- or (R-pn)(phen)2]3+ (pn=1,2-propanediamine; phen=1,10-phenanthroline) were prepared and characterized by absorption, circular dichroism (CD), and 1H NMR spectra. High stereoselectivity in the formation of the diastereoisomers was observed and the Λ-isomer of [Co(S-pn)(phen)2]3+ was formed in preference to the Δ-isomer.
The Formation of 1,2-Bis(alkylthio)-1,2-diphenylethanes by the Lithium Diisopropylamide-induced Fragmentation of Dibenzyl Disulfide Followed by the Trapping with Some Alkyl Halides
Authors: Ikehira Hideyuki , Tanimoto Shigeo
Published: July 2006

It was found that dibenzyl disulfide undergoes lithium diisopropylamide-induced fragmentation to afford several intermediate species which, on trapping with alkyl halides, lead to the formation of 1,2-bis(alkylthio)-1,2-diphenylethanes and α-alkylbenzyl alkyl sulfides.
Ferromagnetic Interactions in Formazanyl–Copper Complexes
Authors: Kawamura Yoshiko , Ohya-Nishiguchi Hiroaki , Yamauchi Jun , Deguchi Yasuo
Published: July 2006

The magnetic susceptibility of four formazanyl–copper complexes have been measured by the use of a torsion balance in the range from 2 K to room temperature. Their ESR parameters have been measured on powdered samples at room temperature and the temperature of liquid nitrogen, and in solution at room temperature in order to elucidate the electronic structures of the complexes. The complexes which have shown the exchange-narrowed pattern in the spectra of powdered samples have been paramagnetic as low as 2 K. Nitro and carboxy derivatives characterized by a single, broad ESR absoption line have positive Weiss constants, indicating ferromagnetic interaction. Especially, the magnetic behavior of the carboxy derivative has been well interpreted in terms of a ground triplet-excited singlet model with the exchange parameter of 24 K. The nitro derivative showed an abnormally low magnetic moment. It has been concluded that the magnetic properties of formazanyl–copper complexes are very sensitive to substitution at the phenyl rings.