bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Crystal Structure of (+)-2,5-Dimethoxy-8-Chloratriptycene
Authors: Kaneda Tsuguhiro , Sakabe Noriyoshi , Tanaka Jiro 
Published: July 2006

Abstract
The crystal structure of (+)-2,5-dimethoxy-8-chlorotriptycene has been investigated by the X-ray method. The crystal system is monoclinic, and the space group is P21. The cell dimensions are a=8.231, b=13.320, c=8.156 Å, and β=96.49°. The structure was deduced from the Patterson map and from the calculation of the R-factor minimized by varying the rotational and translational parameters. The structure parameters were refined by the block-diagonal least-squares method by using 1227 independent reflections; the final R-value was 0.073. The absolute configuration was determined to be 1R6S from the CuKα anomalous scattering of the chlorine atom.
Synthesis of Furfuryl and Nitrofurfuryl Derivatives of Adenine and Uracil
Authors: Fukatsu Shunzo , Sawa Aiko , Umezawa Sumio 
Published: July 2006

Abstract
Condensation of 5-nitrofurfuryl iodide with uracil in dimethylformamide in the presence of lithium hydride gave 1-(5′-nitrofurfuryl)uracil. When the iodide was treated with adenine, 3-substituted adenine was mainly obtained, whereas the analogous reaction of benzamidopurine gave 9-substituted adenine. These compounds showed antitumor and broad antibacterial activity. Furfuryl derivatives were also described.
Magnetic Properties of Nonbenzenoid Aromatic Hydrocarbons
Authors: Yamaguchi Hiroyuki , Nakajima Takeshi 
Published: July 2006

Abstract
The magnetic susceptibilities for nonbenzenoid aromatic hydrocarbons have been examined by using the modified London-Hoarau method in the framework of the Wheland-Mann-type SCF MO approximation. By taking into account the double-bond fixation quite common in these molecules, we obtained a general agreement between the calculated results and the available experimental values.
The Electronic Spectra of Paracyclophadiynes
Authors: Takabe Tetsuko , Tanaka Masashi , Tanaka Jiro 
Published: July 2006

Abstract
The electronic absorption spectra of [3,3]-paracyclophadiyne and [4,4]-paracyclophadiyne have been investigated in solution and in the crystalline state. A trans-annular interaction between the diacetylene group and the benzene ring has been found, and a theoretical study has been made to confirm the assignment. The bathochromic shift and the CT band from the benzene ring to the diacetylene group are particularly noticeable for [3,3]-paracyclophadiyne, where the inter-group distance is significantly shorter than the normal van der Waals distance.
N-Alkylideneanilines. III. Behavior of N-Isopropylideneanilines in Methanol-d4
Authors: Iwamura Hiizu , Tsuchimoto Michiko , Nishimura Shigeo 
Published: July 2006

Abstract
When N-isopropylideneanilines are dissolved in methanol-d4, three types of reactions, exchange of protons in isopropylidene moiety, formation of carbinolamine ethers, and liberation of anilines with formation of acetone dimethyl acetal take place as revealed by NMR spectra of the solutions. The H–D exchange reaction is favored by electron-releasing ring substituents and yet is considerably slower than the rates of the E–Z isomerization of the corresponding imines. The carbinolamine ethers are formed when the substituents are strongly electronegative. Formation of acetone dimethyl acetal occurs additionally with imines carrying halogen atoms as the ring substituents. The competitive reaction mechanism is proposed.
The Telomerization of Methyl Acetate and Methyl Cyanoacetate with Ethylene
Authors: Fujimoto Tsutomu , Hirao Ichiro 
Published: July 2006

Abstract
The telomerization of methyl acetate and cyanoacetate with ethylene initiated by di-tert-butyl peroxide was investigated. Methyl esters of linear and α-branched alkanoic acids, and linear and α-branched alkyl acetates, as well as hydrocarbons, were identified in the system of methyl acetate. The methyl esters of linear and α-branched α-cyanoalkanoic acids were identified in the system of methyl cyanoacetate, but no alkyl cyanoacetates could be found. It was suggested that intramolecular 1,5-hydrogen transfer in telomer radicals with two ethylene units and a chain-transfer reaction to the telomers gave the branched telomers. The chain-transfer constants were estimated in the system of methyl cyanoacetate. The introduction of the cyano group to methyl acetate at the α-position gave a favorable system for chain-transfer reactions and facilitated intramolecular 1,5-hydrogen transfer in the telomer radicals. The relatively higher relative reactivity of the methoxy group to the acetyl group in methyl acetate in the telomerization with ethylene was discussed.
Studies of Tritylated Sucroses. III. NMR Studies of Tritylacetylsucroses
Authors: Otake Toshiki 
Published: July 2006

Abstract
Seven tritylated derivatives have been synthesized by the tritylation of the primary hydroxyl group of sucrose. The 1H NMR spectra of their peracetyl derivatives have been determined at 100 MHz and 220 MHz in order to assign the sugar-ring-proton signals with the aid of the double-resonance technique and NMR spin simulation. The relationship between the chemical shifts of their methine protons and the substituted position of the bonded trityl groups is discussed. Crystalline 1′-mono-O-tritylsucrose derived from 6,6′-di-O-palmitolysucrose is also described.
Catalytic Hydration of Pyridinecarbonitriles in the Presence of [Cu(en)2]Cl2·2H2O and CuCl2·2H2O
Authors: Watanabe Ken-ichi , Murayama Kiyoshi 
Published: July 2006

Abstract
Spectrophotometric studies on the catalytic hydration of 2-pyridinecarbonitrile derivatives in the presence of [Cu(en)2]Cl2·2H2O and CuCl2·2H2O under nearly neutral conditions revealed that the products are their amides. In some cases, the yields were calculated from the weight of amides obtained. The hydration of the nitrile group was influenced by electronic and steric effects. Selective hydration of the nitrile group in α-position was observed in the case of dinitrile. The selectivity was applied to hydrolysis of nitriles to carboxylic acids.
Attempted Synthesis of Diphenylmethylenecyclobutanetrione and the Anomalous Behavior of Its Monoacetal, 4,4-Dimethoxy-2-diphenylmethylenecyclobutane-l,3-dione
Authors: Toda Fumio , Yuwami Koji 
Published: July 2006

Abstract
Neither the oxidation of 2-diphenylmethylenecyclobutane-1,3-dione (I) with SeO2 nor the hydrolysis of 4,4-dibromo- (III) and 4,4-dimethoxy-2-diphenylmethylenecyclobutane-1,3-dione (IV) afforded the title cyclobutanetrione (II). The title acetal (IV) was dissolved in coned HCl-MeOH without hydrolysis, probably in the protonated form (X) on its carbonyl oxygen. The basification of a solution of IV in coned HCl–MeOH-d4 recovered the IV undeuterated. On the other hand, IV was dissolved in KOH-MeOH in the form of the enolate anion (XII). The acidification of a solution of IV in KOH–MeOH-d4 afforded the deuterated acetal (IV-d6).
Telomerization of Ethylene with Chloroform Initiated by N-Chloroalkylamines
Authors: Asahara Teruzo , Sen\={o} Manabu , Ohtani Noritaka 
Published: July 2006

Abstract
N-Chloroalkylamines initiate the telomerization of ethylene with chloroform to give α,α,α-trichloroalkanes CCl3(C2H4)nH(I), which are the same products as those obtained by peroxide-initiated reactions. The N-chloro-alkylamine–iron and N-chloroalkylamine–ferrous chloride systems also initiate the reaction of ethylene with chloroform to afford α,α,ω-trichloroalkanes CHCl2(C2H4)nCl (II) as the main product, and a small amount of I along with other teJomers. The rate of the reaction and the composition of the products vary widely with the kind of N-chloroalkylamine. The reaction mechanism was discussed, a “caged radical” mechanism being proposed for the N-chloroalkylamine-ferrous chloride system.
Oxidation of Chromium(II) Complexes. I. Kinetics of the Oxidation of Tris(2,2′-bipyridine)- and of Tris(1,10-phenanthroline)chromium(II) Complexes with Hexaamminecobalt(III) Ion
Authors: Narusawa Yoshio , Kimura Masao , Nakano Kunio 
Published: July 2006

Abstract
Kinetic studies have been carried out on the oxidation of [Cr(bipy)3]2+ and [Cr(phen)3]2+ with [Co(NH3)6]3+(bipy and phen denote 2,2′-bipyridine and 1,10-phenanthroline, respectively). The rate law is found to be −d[Cr(II)]/dt=k1[Co(III)][Cr(II)]+k2[Cr(II)]. Simulation procedures with an analogue computer were applied for the analysis of these reactions. The rate constant k1 (direct oxidation) and k2 (dissociation) for [Cr(bipy)3]2+ were 180 M−1 s−1 and 0.120 s−1 (μ=0.11 with NaCl, at 25 °C) and those for [Cr(phen)3]2+ were 310 M−1 s−1 and 0.630 s−1 (μ=0.20 with NaCl, at 25 °C), respectively. The larger value of k1 for [Cr(phen)3]2+ as compared with that of k1 for [Cr(bipy)3]2+ was interpreted as being due to the good electron conductivity of the phenanthroline as a ligand in the activated state. The activation parameters were obtained as follows: in the case of [Cr(bipy)3]2+, ΔH\eweq=7.5 kcal/mol and ΔS\eweq=−23 e.u. for the k1 path, and ΔH\eweq=17.2 kcal/mol and ΔS\eweq=−5 e.u. for the k2, path; and in the case of [Cr(phen)3]2+, ΔH\eweq=8.2 kcal/mol and ΔS\eweq=−20 e.u. for the k1 path, and ΔH\eweq=21.2 kcal/mol and ΔS\eweq=+12 e.u. for the k2 path.
Effects of Additives on Solid State Reaction. I. A Kinetic Study of the Effects of Halides of the Formation of MgAl2O4
Authors: Shimada Shiro , Furuichi Ryusaburo , Ishii Tadao 
Published: July 2006

Abstract
The mechanism for the promoting effects of additives on the formation of MgAl2O4 has been systematically discussed from the results of kinetic measurements. A mixture of MgO and α-Al2O3 powder containing 10 mol% additives (LiF, NaF, MgF2, GaF2, BaF2, NaCl or CaCl2) and that without additives were isothermally heated in N2 atmosphere in the temperature ranges 670–1142°C and 1190–1360 °C. The diffusion-controlled Jander’s equation was applied to all kinetic data obtained. In the case of fluoride additives, it has been found that the promoting actions are in the order LiF≥NaF&gt;BaF2&gt;MgF2&gt;CaF2 and that the cations of fluorides play an important role in accelerating diffusion. The same promoting mechanism seems to be applicable in the case of chloride additives.
The Thermal Deaquation-Anation Reactions of Aquopentamminechromium(III) Complexes in the Solid State
Authors: Nagase Kenzo , Yokobayashi Hiroko 
Published: July 2006

Abstract
The thermal deaquation-anation reactions of aquopentamminechromium(III) nitrate, chloride, bromide, and iodide in the solid state were investigated by the techniques of TG, DSC, X-ray powder diffraction analysis, and manometry. The first-order rate constants were obtained by isothermal kinetics. The activation enthalpies calculated from the first-order rate constants increased in the order: the nitrate(24.3)&lt;the chloride(26.4)&lt;the bromide (29.7)&lt;the iodide(30.7 kcal/mol). The enthalpy changes by DSC were 12.3, 6.5, 6.3, and 7.0 kcal/mol for the nitrate, chloride, bromide, and iodide respectively. The slight deviation from the first-order kinetics was observed in cases of the nitrate and the chloride.
Autoxidation of Isobutyraldehyde
Authors: Miyajima Shingo , Inukai Takashi , Harada Hiroshi , Yoshizawa Ryo , Hirai Tadahiro , Matsunaga Kazutoshi , Harada Masato 
Published: July 2006

Abstract
The liquid phase autoxidation of isobutyraldehyde to peroxyisobutyric acid was investigated with ozone as an initiator. The selectivity of the peroxyacid increases with decrease in the amount of aldehyde converted per unit volume of reacting fluid, increase in the ozone feed rate, and decrease in temperature. A few percent of water in solvents increases the selectivity, although too much water brings about a reverse effect. Isopropyl alcohol, acetone, isopropyl formate, propane, propylene, carbon dioxide, and carbon monoxide are observed as by-products besides isobutyric acid. Purified peroxyisobutyric acid (97.2 wt%) was obtained by fractionally distilling the autoxidation product and some of its physical properties were determined. The utility of the peroxyacid as an epoxidizing agent is described.
Application of Chemical Reactions on Thin-layer Chromatoplates. IV. Triterpenes
Authors: Osman A M , Younes M El-Garby , Ata F M 
Published: July 2006

Abstract
Some specific reactions of triterpenoids had been performed on thin-layer chromatoplates. The reactions conducted were: oxidation with oxygen in K-t-butoxide, benzilic acid rearrangement, decarboxylation with lead tetraacetate, Wolff-Kischner reduction, reduction with sodium borohydride, reduction with lithium aluminium hydride, oxidation with chromium trioxide in pyridine and in acetic acid, oxidation with manganese dioxide in chloroform, methylene chloride and isopropyl alcohol, insertion of an oxygen atom in ring A of triterpenoids by the formation of acid anhydride and reduction by a modified Clemmensen method.
The Mass Spectra of Heteroaromatics. II. Mass-spectral Fragmentation of 5-Nitro-2-furohydrazide Imide and Its N2-Acyl Compounds
Authors: Kato Yasuhiko 
Published: July 2006

Abstract
The high-resolution mass spectra of 5-nitro-2-furohydrazide imide and its N2-acetyl, N2-propionyl, and N2-butyryl compounds have been examined. The major fragmentation pathways of the compounds were thus deduced.
Derivatives of Cyclic Bisulfides. III. A New Method of Deoxygenation of Thiolsulfinates and Thiolsulfonates with Inorganic Cyanide
Authors: Tamagaki Seizo , Hirota Hiroo , Oae Shigeru 
Published: July 2006

Abstract
The reaction of rigid cyclic thiolsulfinates and thiolsulfonates such as 1,2-dithiaacenaphthene S-oxide and S,S-dioxide with inorganic cyanide afforded the corresponding reduced 1,2-dithiaacenaphthene, but not the open-chain p-tolyl benzenethiolsulfonate. This was explained by the proximity effect due to the rigidly confined S–S bond at peri-position of the naphthalene ring.
Preparation and Structures of Unsubstituted and Monofluorinated 2H(or 4H)-1,3,4-Benzoxadiazines
Authors: Chow Peng Wai , Ishikawa Nobuo 
Published: July 2006

Abstract
Azo-coupling of diazomethane with benzenediazonium-2-oxide yielded 2H-1,3,4-benzoxadiazine while coupling of the same reagent with the monofluoro-substituted benzenediazonium-2-oxide derivatives gave the corresponding 4H-1,3,4-benzoxadiazines.
The Reductive Amination of d-Camphor with the Methylamine and Carbon-13 NMR of the Reaction Products
Authors: Kiyooka Syun’ichi , Suzuki Kojiro 
Published: July 2006

Abstract
The effects of catalysts (Raney Ni, 5% Pd–C, and PtO2) in the title reactions have been discussed. The PtO2 catalyst is excellent in reductive power and in selectivity. The CMR spectra of the reaction products (I, II, and III) are assigned, and the N-protonation shifts are further measured.
Thermal Decay of the Colored Form in Photochromism of 2-Hydroxy-4-methoxytriphenylmethanol in n-Hexane
Authors: Hamai Sanyo , Kokubun Hiroshi 
Published: July 2006

Abstract
It was found that, like 2-hydroxytriphenylmethanol (HM), 2-hydroxy-4-methoxytriphenylmethanol (HMM) shows photochromism as well as thermochromism. Photo- and thermochromism of HMM occur even in n-hexane, in which a photochemical irreversible reaction occurs for HM. In n-hexane solution of HMM, a three-stage thermal fading pattern was observed at room temperature and at lower temperatures, the pattern becoming a one-stage type at a higher temperature. Mechanical stirring of a sample solution caused a decrease in the concentration of the colored form in n-hexane at room and lower temperatures but not at a higher temperature. These phenomena are caused by the backward reaction on the wall of a sample cell including diffusion as the rate-determining step. In n-hexane–dimethoxyethane (or acetonitrile) mixed solvents, the first-order rate constant becomes smaller with increase in the dimethoxyethane (or acetonitrile) concentration. From a certain concentration, shaking of a cell causes no decrease in the concentration of the colored form.
The Catalytic Activity of AgX-type Zeolite for the Isomerization of 1-Butene
Authors: Sugihara Hiroshi , Chen Ling Yuan , Yasumori Iwao 
Published: July 2006

Abstract
The catalytic activity of X-type zeolite exchanged by Ag+ was studied for the isomerization of 1-butene. The activity gradually increased with the degree of exchange up to ca. 60%, whereafter it rose steeply. A good correlation was found between the activity and the number of acid sites of H0 less than 3.3. Both preferences, that for the formation of cis-2-butene from 1-butene and that for the geometrical isomerization rather than the double bond shift, indicated that the reaction proceeds via a carbonium-ion intermediate formed on an acidic site. In the region of exchange around 40%, however, the cis/trans ratio in the 2-butenes produced was less than unity and a change in the reaction mechanism was suggested. Treatment with H2 enhanced the activity of exchanged zeolite by a factor of 102–103 without any change in the character of the reaction. These results were attributed to the formation of proton-X-zeolite by the replacement of Ag+ with a proton. This conclusion was confirmed by the analysis of deuterium exchange during the isomerization on D2-treated AgX.
Charge-transfer Interaction and Chemical Reaction. V. Reaction of o-Phenylenediamine with Chloranil
Authors: Nogami Takashi , Hishida Tadanori , Shirota Yasuhiko , Mikawa Hiroshi , Nagakura Saburo 
Published: July 2006

Abstract
The reaction of o-phenylenediamine with chloranil in ether was studied by measuring visible and ultraviolet absorption spectra at various temperatures between −78 °C and room temperature. Dehydrogenation of o-phenylenediamine by chloranil occurred, o,o′-diaminoazobenzene, 2,3-diaminophenazine and tetrachlorohydroquinone being produced as main reaction products. It was suggested that the reaction involves o-benzoquinone di-imine as an intermediate. For the sake of confirmation, o-benzoquinone di-imine was prepared by an independent method, and its reaction with o-phenylenediamine was examined. The difference in reactivity of isomeric phenylenediamines toward chloranil is discussed.
Interaction between Electron Donor and Acceptor: MINDO/2 Calculations on the Ammonia–I2, Benzene-I2 and Benzene–TCNE Systems
Authors: Ohta Toshiaki , Fujikawa Takashi , Kuroda Haruo 
Published: July 2006

Abstract
The MINDO/2 method was applied to typical molecular complexes such as ammonia–I2, benzene–I2, and benzene–TCNE, these bimolecular systems being treated as single molecules. The intermolecular interaction energy was calculated as a function of intermolecular distance. Stable complex formation with a reasonable stabilization energy was predicted in the ammonia–I2 system. It was predicted in the benzene–I2 system for the axial model, but not for the resting model. However, the stabilization energy for the former was found to be too large. No stable conformation was found in the case of the benzene–TCNE system.
ESR Study on Fluorescein Semiquinone Radical
Authors: Niizuma Shigeya , Sato Yoshiharu , Konishi Shiro , Kokubun Hiroshi 
Published: July 2006

Abstract
The ESR spectrum of the fluorescein semiquinone radical (dianion form) produced by illumination of an alkaline aqueous solution of uranine and leuco-uranine at pH between 11 and 14 was observed and its hfs constants were determined by comparing the spectrum with those of the mono- and trianion forms of fluorescein semiquinone and those of eosm semiquinone reported by Leaver. Six protons in the xanthene ring were found to be comprised of three pairs of magnetically equivalent protons, which suggests a certain dynamic mechanism to average the coupling constants. From a temperature dependence of the line width, protonation to the –O− group followed by deprotonation from the –OH group was proposed as a plausible mechanism.
The Estimation of Rate Constants in Systems of Linear and Nonlinear Differential Equations Using the Polynomial-approximated Least Squares-error and Iterative Search Technique
Authors: Ohkubo Katsutoshi , Sakamoto Hiroyuki , Tsuchihashi Kohji 
Published: July 2006

Abstract
A new technique is proposed for estimating the rate constants in systems of linear or nonlinear differential equations, using a polynomial approximation of the observed concentrations of species participating in the reaction and an iterative search technique. The method is implemented by minimizing the errors of the concentrations (of species), as computed by the theoretical equations derived from the linear differential equations or by the trapezoidal averaging simulation, relative to those calculated by the polynomial approximation. The present technique requires the concentrations (at the initial reaction stage) of s-2 species (the s species takes part in the reaction). Two kinetic example, A\ightleftarrowsB\ightleftarrowsC and S+E\ightleftarrowsES→P, have been used to illustrate and develop the present technique.
The Protonation of the TCNQ Anion Radical by Hydrogen Chloride
Authors: Yamagishi Akihiko , Sakamoto Masahiro 
Published: July 2006

Abstract
The kinetics of the protonation of sodium salt of 7,7,8,8-tetracyanoquinodimethane (Na+TCNQ\ewdot) by hydrogen chloride in alcohols and acetonitrile was investigated, using a stopped-flow apparatus. In methanol, the protonation rate is first-order in HCl and second-order in Na+TCNQ\ewdot, while in ethanol, the rate is one-half-order in HGl and second-order in Na+TCNQ\ewdot. The protonation rate in acetonitrile is first-order in HCl, but it deviates from second-order in Na+TCNQ\ewdot. These results are interpreted in terms of the rapid formation of a protonated intermediate in the initial stage of the reaction, according to TCNQ\ewdot+H+\ightleftharpoonsHTCNQ\ewdot The reversibility of this reaction is well demonstrated by the second-order dependence of the rate on Na+TCNQ\ewdot. The rate is also compared with the protonation rate of semiquinones, such as sodium salts of p-chloranil and 2,3-dicyano-l,4-benzoquinone, from the view point of the difference in reactivity between carbon and oxygen acids.
Heat Capacity of Nematogenic N-p-Ethoxybenzylidene-p′-butylaniline between 14 and 375 K
Authors: Sorai Michio , Nakamura Teruo , Seki Syûzô 
Published: July 2006

Abstract
The heat capacity of a low-temperature liquid crystal EBBA (N-p-ethoxybenzylidene-p′-butylaniline) of 99.75% (mol) purity was measured in the range 14–375 K with an adiabatic calorimeter. The melting point Tm was 305.62 K, and the enthalpy and entropy of fusion 27.09 kJ mol−1 and 88.71 J K−1 mol−1, respectively. The temperature of mesomorphic transition Tc from nematic to isotropic liquid was 349.08 K, and the enthalpy and the entropy changes due to the mesomorphic transition were 1.553 kJ mol−1 and 4.524 J K−1 mol−1, respectively. Excess heat capacity due to the mesophase transition, C(excess), is represented by C(excess)∼ε−0.7 in the range 10−4&lt;ε&lt;10−1.5, where ε≡|T–Tc|⁄Tc. This implies that the mesomorphic transition of EBBA can be regarded as of critical phenomena, characterized by a second-order rather than a first-order nature.
Studies of Peptide Antibiotics. XXXI. Syntheses of iso-Gramicidin S and iso-[2,2′-Lysine]-Gramicidin S
Authors: Takiguchi Hideo , Izumiya Nobuo 
Published: July 2006

Abstract
Structural isomers of gramicidin S and [2,2′-lysine]-gramicidin S, namely iso-gramicidin S and iso-[2,2′-lysine]-gramicidin S, were prepared to investigate the influence of the ring size for antibacterial activity and conformation of natural gramicidin S. Each isomer involves two peptide bonds between carboxyl group of valine residue and ω-amino group of ornithine or lysine residue. Two isomers showed no antibacterial activity toward several microorganisms. In the experiment of optical rotatory dispersion, two isomers showed similar shaped curves as gramicidin S in a solvent of ethanol. In 6 M urea, the trough of two isomers was moved significantly, whereas that of gramicidin S remained constant.