bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrode Reactions of Several Transition Metal Ions in Aqueous Polyelectrolyte Solutions as Studied by DC and Fourier Transform Polarography
Authors: Imai Noboru , Hirota Michio , Umezawa Yoshio , Fujiwara Shizuo
Published: July 2006

The kinetic parameters, ks for several metal ions are decreased down to 1/10–1/50 in the presence of sodium polyacrylate, although the diffusion of metal ions in the same system differs little with and without sodium poly aclylate.
A Theoretical Consideration of the 13C NMR Chemical Shift of Protonated Systems. I. The Acetone–Sulfuric Acid System
Authors: Ando Isao , Kondo Masahiro , Nishioka Atsuo , Watanabe Shosuke
Published: July 2006

A quantum-chemical method has been developed using a point-charge model to calculate the 13C chemical shift for protonation in an acidic solution. This method has been applied to the acetone-sulfuric acid system; the gross tendencies between the observed and calculated results agree.
Calculations of the Rate Constants for the HX+NO\ightleftharpoonsHNO+X Reactions (X=H, F, Cl, Br, and I)
Authors: Higashihara Tetsuo
Published: July 2006

The rate constants for these hydrogen-transfer reactions:

HX+NO\ightleftharpoonsHNO+X(X=H,F,Cl,Br,and I)

have been calculated by means of the transition-state theory combined with the BEBO method over the temperature range of 250–4000 K. The calculated rate constants were then compared with the experimental kinetic data.
Synthesis and Characterization of (Salicylideneaminoalkyl)phosphonatocopper(II) and [(N-Salicylideneglycylamino)alkyl]phosphonatocopper(II)
Authors: Murase Ichiro , Martell Arthur E
Published: July 2006

The titled compounds have been synthesized by a template reaction of aminoalkylphosphonic acids or glycylaminoalkylphosphonic acids and salicylaldehyde with copper(II) ion. The square-planar structures have been proposed by analogy with corresponding structures of N-salicyclideneglycine or N-salicylideneglycylglycine chelates. The deprotonated peptide nitrogen coordination was confirmed by IR-spectra for the phosphonopeptides chelates.
The Solvent Extraction of Uni- and Bivalent Metal Picrates by Dibenzo-24-crown-8
Authors: Takeda Yasuyuki
Published: July 2006

The overall extraction equilibrium constants (Kex) for the 1:1:1 and 1:1:2 complexes of dibenzo-24-crown-8 (DB24C8) with several uni- and bivalent metal picrates between benzene and water have been determined at 25 °C. The Kex sequences of the uni- and bivalent metal ions with DB24C8 are Tl+>Cs+>Ag+>Rb+>K+>Na+>>Li+ and Ba2+>>Pb2+>>Sr2+>Ca2+, respectively. DB24C8 shows the highest selectivity for Ba2+ among all the alkali and alkaline earth metal ions, but no selectivity for the alkali metal ions. The extractability of DB24C8 for the alkali metal ions is not sensitive to the ratio of the ionic size to the cavity size of DB24G8. The plots of logKex values vs. reciprocal crystal ionic radii of the alkali and alkaline earth metals give straight lines, indicating that these straight lines are related to Born’s formula of solvation free energy.
An MO Study of Organic Sulfur Compounds. Comparison with the Corresponding Oxygen Compounds
Authors: Matsushita Toshio , Osamura Yoshihiro , Misawa Nobuaki , Nishimoto Kichisuke , Tsuno Yuuho
Published: July 2006

The contribution of 3d orbitals of sulfur atom to the electronic structures of the sulfur compounds, H2CS, CH3SH, C6H5SH, and C6H5SCH3 have been studied by means of ab initio MO method. The results have been compared with those of the corresponding oxygen compounds in order to clarify the peculiar properties of the sulfur compounds. The global molecular properties are scarcely affected by the 3d orbitals of sulfur atom since they are energetically highly located. However, the local characters such as charge distributions and LUMO are largely varied by the participation of 3d orbitals.
Kinetics of the Reduction Reaction of Tetranitromethane by Thiosulfate Ion in the Absence and Presence of Copper(II) Ion in Aqueous Mixtures of Methanol and Ethanol
Authors: Kimura Masaru , Shukutani Makiko
Published: July 2006

The kinetics of the reduction reaction of tetranitromethane by the thiosulfate ion in the absence and presence of the copper(II) ion have been investigated in aqueous solution and aqueous mixtures of methanol and ethanol. The mechanism of reaction has been thought to be the following:

C(NO2)4+S2O32−\xrightarrowk1C(NO2)3−+NO2+S2O3−

Cu(II)+S2O32\xrightarrowk2Cu(I)+S2O3−

C(NO2)4+Cu(I)\xrightarrowk3C(NO2)3−+NO2+Cu(II)

2S2O3−\xrightarrowrapidS4O62

The rate constants k1 and k2 have been determined under several conditions. The value of k1 was hardly affected by ionic strength, permittivity, and acetate ion concentration in the reaction solution, whereas k2 was markedly increased with decreasing ionic strength (μ), permittivity (D), and acetate ion concentration. For k2, plots of logk2  vs. μ1⁄2⁄(1+μ1⁄2 and logk2  vs. 1/D gave linear relationships. Under the specified conditions the k2-term in the reaction mechanism accounts for up to 90% of the reaction, the reaction being composed of a copper(II) catalyzed-chain reaction.
Adsorption Behavior of Phosphate Ion on the Iron(III) Complex of a Chelating Resin
Authors: Takeshita Ryoichi , Yoshida Isao , Ueno Keihei
Published: July 2006

Phosphate ion in 0.1 M (1 M=1 mol dm−3) sodium chloride solution was adsorbed selectively on the iron(III) complex of a chelating resin. Coordination unsaturated sites of the resin-bound iron(III) ion were considered to be the adsorption sites for phosphate ion, predominating species being dihydrogenphosphate ion (H2PO4−). Adsorption capacity of the resin increased with the increasing amount of iron(III) ion loaded on the chelating resin, while the molar ratio of the adsorbed phosphate ion to the resin-bound iron(III) ion became less than unity, indicating that only a fraction of the resin-bound iron(III) ion acts as the adsorption site at higher iron content. The steric and electrostatic interactions among the phosphate ions in the resin matrix may interfere with the stoichiometric adsorption of phosphate ion on the resin-bound iron at higher iron content.
The Determination of Berberine by Ion-pair Extraction-Titration, with Tetrabromophenolphthalein Ethyl Ester as the Indicator
Authors: Tsubouchi Masahiro
Published: July 2006

A method has been developed for the determination of berberine as a quinolizinium medicine. The method is based on the solvent extraction-titration of an ion pair. Sodium tetraphenylborate is used as the titrant, with tetrabromophenolphthalein ethyl ester as the indicator in the presence of chloroform. In the two-phase titration, the proposed procedure gives sharp end points as the organic phase changes from blue to yellow. The aqueous phase is colorless throughout the titration. From a p(berberine)-pH diagram, a theoretical titration curve is constructed. The titration curve at pH 6.5 is not too far from the ideal case.
Allylation of Nucleic Acid-Bases with Triallyl Phosphate
Authors: Tanabe Toshizumi , Yamauchi Kiyoshi , Kinoshita Masayoshi
Published: July 2006

Triallyl phosphate alkylated uracil (N-1), thymine (N-1), cytosine (N-1), adenine (N-3 and N-9), and guanine (presumably N-1 or N-7) in a water solution at 60 °C (pH values were 10–10.5 for uracil, thymine, cytosine, and adenine, and 12 for guanine), giving the corresponding allyl derivatives in considerable yields.
The Synthesis of 3′-Methoxy-2′,4,4′,6′- and 2′-Methoxy-3′,4,4′,6′-tetrahydroxychalcone and Some Quinochalcones and a Comparison of Them with Carthamin
Authors: Obara Heitaro , Onodera Jun-ichi , Abe Satoshi
Published: July 2006

3′-Methoxy-2′,4,4′,6′- and 2′-methoxy-3′,4,4′,6′-tetrahydroxychalcone, 2′,4,4′-trihydroxy-, 2′,4-dihydroxy-4′-methoxy-, and 2′-hydroxy-4,4′-dimethoxy-3′,6′-quinochalcone have been synthesized, and their properties have been compared with those of carthamin.
Synthesis of Coleon U 12-Methyl Ether
Authors: Matsumoto Takashi , Takeda Shoji
Published: July 2006

Reduction of 11-benzoyloxy-12-methoxyabieta-8,11,13-trien-7-one with sodium borohydride, followed by dehydration of the resulting alcohols with p-toluenesulfonic acid, afforded the corresponding 6,8,11,13-tetraene derivative. This was converted into 11-benzoyloxy-12-methoxyabieta-8,11,13-trien-6-one (8) via an epoxide. The 6-oxo compound (8) was reduced with lithium aluminium hydride. Subsequent oxidation of the resulting alcohol with m-chloroperbenzoic acid afforded 6β-hydroxy-12-methoxyabieta-8,12-diene-11,14-dione. This compound was further transformed into 11,14-diacetoxy-12-methoxyabieta-8,11,13-trien-6-one (13) by a series of reactions: Jones oxidation, reduction with a mixture of zinc powder and hydrochloric acid, and acetylation. The diacetate (13) was then oxidized with Jones reagent and the 6,7-dioxo product was immediately converted into 11-acetoxy-6,14-dihydroxy-12-methoxyabieta-5,8,11,13-tetraene (15) by repeated column chromatography on silica gel. The tetraene (15) was finally hydrolyzed with hydrobromic acid to give coleon U 12-methyl ether.
A Convenient Synthesis of α-(2-Benzothiazolylthio)alkanoates by Cleavage of β-Keto Esters with 2-Benzothiazolesulfenamides
Authors: Torii Sigeru , Tanaka Hideo , Okumoto Hiroshi
Published: July 2006

α-(2-Benzothiazolylthio)alkanoates were prepared by the reaction of β-keto esters with 2-(morpholinothio)benzothiazole in refluxing alcohols. Sulfenylating cleavage of α-methoxycarbonylcycloalkanones afforded the corresponding ω-alkoxycarbonyl- and/or ω-carbamoyl-α-(2-benzothiazolylthio)alkanoates.
Zeeman Absorption Spectra of 2,3-Dichloro-9,10-anthraquinone Crystals
Authors: Sano Mizuka , Narisawa Takatoshi , Izawa Kohji , I’Haya Yasumasa J
Published: July 2006

Polarized T←S0 absorption spectra were measured for 2,3-dichloro-9,10-anthraquinone melt-grown single crystals in a magnetic field of 50 kOe. From the analysis of the Zeeman absorption patterns, the lowest triplet state of 2,3-dichloro-9,10-anthraquinone in the crystalline state has been assigned to 3A1(ππ*). The c-polarized first absorption peak at 21734.7 cm−1 has been interpreted as gaining intensity mainly from an x-polarized transition from the ground state to a B1(nπ*) perturbing singlet state, which is directly spin-orbit-coupled with the y spin-sublevel of the 3A1 state. The a- and b-polarized first peaks, at 21733.9 and 21733.6 cm−1, respectively, have been interpreted as gaining intensity through the configurational mixing of the 3A1(ππ*) state with a nearby 3B1(nπ*) state.
An ESR Study of the Photolysis of N-Nitrosodialkylamines
Authors: Elliot A John , Wan Jeffrey K S
Published: July 2006

The nitroxide radicals which are formed when acidic, neutral, and alkaline solutions containing N-nitrosodialkylamines are photolysed, have been characterized by electron spin resonance spectroscopy. Nitrosamines are found to be photolytically active only in acidic solutions. In neutral and alkaline solutions nitrosamines only participate in secondary reactions involving the alcohol derived radicals. Some possible reaction pathways have been postulated.
Flat-band Potential of p-Type GaP in Acetonitrile Solutions
Authors: Satoh Kiyoshi , Yoneyama Hiroshi , Tamura Hideo
Published: July 2006

An interaction of quinone compounds such as tetrachloro-p-benzoquinone and p-benzoquinone with surface hydroxyl groups of a p-type GaP electrode seems to play an important role in determining the magnitude of photovoltage in acetonitrile solutions. The same holds for p-type InP and Si.
Infrared Emission Spectra of CO2 in the Explosion Reaction of CO and O2 Using a Rapid-Scan Spectrometer
Authors: Tanaka Masako , Nagasaka Shigeo , Sawamura Sadao , Katayama Meiseki
Published: July 2006

The infrared emission spectra of CO2 were observed by means of a rapid-scan infrared spectrometer during the explosion of CO-O2 in a cylindrical vessel. The R-branch band heads of 001-000 and 011-010 were detected. The time dependences of the emission intensities of these band heads, ν1+ν3, and 2ν2+ν3, were studied.
Dissociation Constants of Several Protonated Amines in Propylene Carbonate
Authors: Izutsu Kosuke , Nakamura Toshio , Iijima Izumi
Published: July 2006

The dissociation constants pK(BH+) of five protonated monoamines in propylene carbonate have been determined potentiometrically using a glass electrode which was calibrated in a picric acid-picrate buffer solution. The pK(BH+) values found at 25 °C were 10.1 for aniline, 11.9 for pyridine, 15.9 for ammonia, 17.0 for 1,3-diphenylguanidine, and 17.9 for triethylamine.
Thermochromism of Metal Chelates with Triphenylmethane Complexons in Aqueous Solutions. II. Inhibitive Effects of the Protolysis of Aqua Cu2+ Ion on the Thermochromism of Cu(II)–Xylenol Orange Chelate
Authors: Nakada Shoji , Yamada Mutsuo , Ito Tasuku , Fujimoto Masatoshi
Published: July 2006

Temperature-dependent protolytic equilibrium, Cu(OH2)n2+ \oversetk1\undersetk−1\ightleftharpoons Cu(OH)(OH2)n−1++H+, was found to inhibit thermochromic changes of Cu(II)-Xylenol Orange (XO) chelate in unbuffered weakly acid aqueous solutions. The rate constants, k1 and k−1 at 25 °C and I=0.1 mol dm−3 were evaluated to be 103–104 s−1 and ca. 2×109 mol−1 dm3 s−1, respectively.
The Asymmetric Hydroformylation of Vinyl Acetate
Authors: Watanabe Yoshihisa , Mitsudo Take-aki , Yasunori Yukio , Kikuchi Junichi , Takegami Yoshinobu
Published: July 2006

Vinyl acetate gives selectively (S)-2-acetoxypropanal in 10–24% optical yields by the asymmetric hydroformylation with μ,μ′-dichlorotetracarbonyldirhodium–(−)-DIOP. (R)-Benzylmethylphenylphosphine and neomenthyldiphenylphosphine give low optical yields. The reaction depends essentially on the DIOP/rhodium ratio. Just 2 mol or more of (−)-DIOP per g-atm of rhodium is required for the asymmetric reaction. Other reaction variables (temperatures and pressures of hydrogen and carbon monoxide) have minor effects.
Phase Transfer Catalyzed Reaction of Organic Thiocyanates with Hydroxide Ion
Authors: Yano Yumihiko , Kurashima Akira , Tagaki Waichiro
Published: July 2006

The reactions of 9-fluorenyl, phenacyl, benzhydryl, and benzyl thiocyanates (or the corresponding bromides with sodium thiocyanate) with hydroxide ion under phase transfer conditions afforded 9,9′-bifluorenylidene, 2,3-dibenzoylthiirane, thiobenzophenone and dibenzyl disulfide, respectively.
Neutron Diffraction Study of Aqueous Ionic Solutions. I. Aqueous Solutions of Lithium Chloride and Caesium Chloride
Authors: Ohtomo Norio , Arakawa Kiyoshi
Published: July 2006

The structure factors Sm(Q) for aqueous solutions of LiCl and CsCl at room temperature, including those for heavy water, have been determined by means of the time-of-flight (TOF) neutron diffraction method using an electron linear accelerator (LINAC). Analysis of the diffraction data has been carried out for the aqueous ionic solutions as well as for pure heavy water. The following results were obtained with respect to the structure of the nearest hydration shell: (a) the coordination numbers are 4 for Li+ and 6 for Cl− in the LiCl solution, and 8 for Cs+ and 6 for Cl− in the CsCl solution, (b) the average ion-oxygen distances are 1.90±0.05 Å for Li+, 2.95±0.10 Å for Cs+ and 3.10±0.05 Å for Cl−, and (c) around cations water molecules take the configuration to orient the axis of one of two lone-pair hybrids on a straight line joining an oxygen atom and a cation.
Charge-transfer Absorption Intensity and Magnetic Property of Solid Ion Radical Salts
Authors: Iida Yôichi
Published: July 2006

The electronic spectrum of solid ion radical salt is known to be different from the monomer spectrum of the radical ion and to show an intermolecular charge-transfer transition between ion radicals in the low-energy region. The intensity of the charge-transfer absorption was theoretically obtained by applying one-dimensional half-occupied Hubbard model to the segregated stack of ion radicals of solid ion radical salts. The intensity of the charge-transfer absorption was then correlated to the magnetic properties of those solid ion radical salts.
The Electronic Spectra of Anthraquinone in Shpol’skii Matrices and in Crystals at 4.2 K
Authors: Kanezaki Eiji , Nishi Nobuyuki , Kinoshita Minoru
Published: July 2006

The lower excited singlet and triplet states of 9,10-anthraquinone-d0 and -d8 are examined in normal alkanes and in crystals at 4.2 K with the phosphorescence excitation method. The S←S0 and T←S0 excitation spectra are analyzed by considering environmental effects on and isotopic changes in the vibrational structure. The low energy region of the spectra can be explained without taking the Au origin in close proximity of the B1g origin into account. The latter origin band in the singlet and triplet spectra in hexane and in crystals, respectively, is weaker by a factor of 10−3–10−2 than the strongest vibronic band in the respective regions. No clear evidence has been found about the location of the singlet and triplet Au states in the excitation spectra.
Effect of Pressure on Iodine Complexes. II. Absorption Spectra of the Charge Transfer Bands with Diethyl Ether, Diethyl Sulfide, and Diethyl Selenide in Heptane
Authors: Sawamura Seiji , Taniguchi Yoshihiro , Suzuki Keizo
Published: July 2006

Absorption spectra of the CT bands of I2 complexes with Et2O, Et2S, and Et2Se in heptane have been measured up to 4400 bar at 25 °C. The equilibrium constants and the volume changes accompanying complex formation, and the molar extinction coefficients and absorption maxima have been estimated. The volume changes were comparable with those estimated by the visible I2 bands and by the X-ray data of the I2 complexes in the crystalline state. In the CT bands of Et2S–I2 and Et2Se–I2 complexes inversion of shift from red to blue has been observed with increasing pressure though the CT band of Et2O–I2 complex shifted only through red. This inversion appears to be characteristic of the strong CT complex. Enhancement of the molar extinction coefficient of the CT band has been found with increasing pressure suggesting enhancement of the CT interaction between I2 and the n-donor.
The Mechanism of Catalyzed Hydrogen–Deuterium Exchange on Gold Deposited over Poly(tetrafluoroethylene)
Authors: Iida Itsuo
Published: July 2006

The H2–D2 exchange reaction over Au(0.3%)/PTFE(poly(tetrafluoroethylene)) was studied. The apparent activation energy was found to be 29 kj mol−1. The dependence of the reaction rate on the total pressure was measured at 518, 432, and 393 K. It was found that the pressure exponent of the exchange reaction decreases with the increase in the total pressure and that in the lower pressure range, the reaction order is as high as 2. The rate equation obtained from the pressure dependence was R=k{KP⁄(1+KP)}2. Accordingly, it was concluded that the H2–D2 exchange reaction over gold takes place between molecularly adsorbed hydrogen and deuterium through a dimeric intermediate. The heat of adsorption on the active sites in the gold surface was 5.9 kj mol−1.
Studies on the Aqueous Solutions of Guanidinium Salt. XI. Volume Changes of Mixing of Aqueous Solutions of Guanidinium Bromide and Tetraalkylammonium Bromide at 25 °C
Authors: Miyajima Koichiro , Yoshida Hiromitsu , Nakagaki Masayuki
Published: July 2006

The volume changes on mixing aqueous solutions of guanidinium bromide with those of tetrabutyl- and tetramethylammonium bromide were measured with a vibration densimeter at 25 °C. The excess volume change of mixing was positive and large for the system of tetrabutylammonium bromide–guanidinium bromide–water. On the basis of the interaction parameters of Friedman’s formalism, this result was interpreted in terms of an interaction between guanidinium cation and tetrabutylammonium cation through the change of water structure.
Vapor Pressure Osmometry and Conductance Studies of Solutions of Bis(tetraalkylammonium) Electrolytes in Methanol, Ethanol, and 2-Propanol
Authors: Lee Ha Chung , Nomura Hiroyasu , Miyahara Yutaka , Verrall R E
Published: July 2006

Vapor-pressure depressions and electric conductivities have been measured for bis(tetraalkylammonium) electrolytes in methanol, ethanol, and 2-propanol. The analysis of the data of vapor pressure osmometry (VPO) of these bolaform salts was carried out taking into account the two-step dissociation equilibrium as follows.

M2++2X−\undersetKdI\ightleftarrowsMX++X−\undersetKdII\ightleftarrowsMX2

In each solvent, the ionic association constants, KaI and KaII (Ka=1⁄Kb), tend to decrease with increasing ionic size. This tendency is greater in KaI than in KaII. The KaII values of bis(tetraalkylammonium) electrolytes show virtually no dependence on the dielectric constant of solvent. On the contrary, the values of KaII strongly depend on the dielectric constant of solvent. Using the values of KaI and KaII in 2-propanol, the ultrasonic relaxation data were analyzed.
Potentialities of Field Desorption Mass Spectrometry Using Emitter Current Programmer for Direct Analysis of Multicomponents
Authors: Shiraishi Hiroaki , Otsuki Akira , Fuwa Keiichiro
Published: July 2006

The influence of emitter current on field desorption (FD) mass spectra was examined with use of an emitter current programmer (ECP). Reproducibility of FD mass spectra measured by electronic detection is improved with ECP and the integration of stored spectra on the computer. The FD mass spectra of some surfactants are shown as an example of complex mixture. The FD mass spectra of poly(oxyethylene) alkylphenyl ethers show that the distribution pattern of molecular ion peaks depends upon emitter current. The fractional desorption also occurs in the FD mass spectra of α-hydro-ω-(octadecylamino)poly(oxyethylene) measured with a constant emitter current. The emitter current required for desorption of hexadecyltrimethylammonium chloride is greatly affected by coexisting with another ammonium salt. Use of ECP supplies information on the analysis of multicomponents.
Use of a Programmable Monochromator and a SIT Detector in Flame Atomic Emission Spectrometry
Authors: Furuta Naoki , McLeod Cameron W , Haraguchi Hiroki , Fuwa Keiichiro
Published: July 2006

A multielement detection system which uses a programmable monochromator and a SIT image detector has been constructed, and evaluated by measuring the flame emission of 22 elements in the nitrous oxide–acetylene flame. The detection limits for the elements under optimized experimental conditions are reported, and are compared with those obtained by a standard photomultiplier tube.
Sodium Ion Exchange on Crystalline Zirconium Titanium Phosphate
Authors: Yazawa Yutaka , Eguchi Toru , Takaguchi Kazunori , Tomita Isao
Published: July 2006

A new ion exchanger, crystalline zirconium titanium phosphate with variable zirconium to titanium mole ratios has been prepared and the sodium ion exchange behavior studied. In the zirconium-rich exchanger a half-exchanged monosodium phase was produced. This differs from the titanium-rich exchanger where a disodium phase was formed without formation of the intermediate monosodium phase. The pH titration curves were complicated but a trend emerged with variation in the Zr/Ti ratio. On the basis of the X-ray evidence and the shapes of the titration curves it is thought that the synthesized phosphates are solid solutions rather than a mechanical mixture of the two metal phosphates.
Synthesis of 4-(Glycosyl)isoxazoline N-Oxides and Related Substances
Authors: Kaji Eisuke , Ichikawa Hiromi , Zen Shonosuke
Published: July 2006

4-(Glycosyl)isoxazoline N-oxides were synthesized directly from aldehydo sugars by one-step cyclization with double mole of methyl nitroacetate in a satisfactory yield. 2,3-O-Isopropylidene-d-glyceraldehyde reacted with methyl nitroacetate to give 4-(1,2-O-isopropylidene-d-glycero-dihydroxyethyl)-3,5-bis(methoxycarbonyl)isoxazoline N-oxide. The same treatment of 2,3 : 4,5-di-O-isopropylidene-aldehydo-l-arabinose and penta-O-acetyl-aldehydo-d-glucose also gave the corresponding homologs. From the corresponding cyclic aldehydo sugars, 4-aldofuranosyl-3,5-bis(methoxycarbonyl)isoxazoline N-oxides, e.g. 4-(2,3-O-isopropylidene-β-d-erythrofuranosyl)-, 4-[(4R)-3-O-benzyl-1,2-O-isopropylidene-β-l-threofuranos-4-yl]-, 4-(2,3,5-tri-O-benzyl-β-d-ribofuranosyl)-, and 4-(2,3,5-tri-O-benzoyl-β-d-ribofuranosyl)-derivatives were synthesized. The latter was converted into 3,5-dicarbamoyl-4-(β-d-ribofuranosyl)isoxazoline by deoxygenation followed by carbamoylation and deprotection.
Structural Studies of the Interaction between Indole Derivatives and Biologically Important Aromatic Compounds. IV. The Crystal and Molecular Structure of Tryptamine: Adenin-9-ylacetic Acid (1 : 1) Hemihydrate Complex
Authors: Ishida Toshimasa , Inoue Masatoshi , Senda Susumu , Tomita Ken-ichi
Published: July 2006

The crystal structure of tryptamine: adenin-9-ylacetic acid (1 : 1) hemihydrate complex has been determined by the X-ray method. The crystal is monoclinic, space group P21/c with unit-cell dimensions: a=9.164(2), b=6.908(1), c=29.524(4) Å and β=110.98(2)°. The structure was solved by application of MULTAN and refined by the block-diagonal least-squares method to give a final R-value of 0.064. No specific interaction between indole and adenine rings is observed. Both component molecules are held together by three-dimensional frameworks of hydrogen bonds around a twofold screw axis to form an infinite helical array along the b-direction. Two kinds of dimer formation around a center of symmetry are observed between adenin-9-ylacetic acid molecules.
Photochemical Reaction at 3-O-Functional Group of Methyl 4,6-O-CycIohexylidene-2-deoxy-2-methoxycarbonylamino-α-d-glucopyranoside Derivatives
Authors: Kishi Teruo , Tsuchiya Tsutomu , Umezawa Sumio
Published: July 2006

3-O-Acetyl, 3-O-thiocarbonyl, and 3-O-sulfonyl derivatives of the titled compound have been irradiated in aqueous HMPT. Conversion of the 3-O-acetyl derivative to the corresponding 3-deoxy compound was most effective. 3-O-Dimethylthiocarbamoyl-, 3-O-(methylthio)thiocarbonyl- and 3-O-(1-imidazolyl)thiocarbonyl derivatives were found to give the 3-deoxy compound accompanied by 3-hydroxy compound, whereas the 3-O-phenyl(thiocarbonyl) derivative did not give the 3-deoxy compound. 3-O-Methylsulfonyl and 3-O-tolylsulfonyl derivatives gave the 3-hydroxy compound. Under low-energy irradiation, the (1-imidazolyl)thiocarbonyl derivative gave the 3-deoxy compound in moderate yield.
A Kinetic Study of the Simultaneous Dealkylation and Disproportionation of Cumene over Silica–Alumina
Authors: Take Jun-ichiro , Tozawa Yoichi , Yoneda Yukio
Published: July 2006

Cumene has been passed over a silica–alumina bed at low temperature (210 to 254 °C) and at cumene pressures of 0.003 to 0.023 atm. Both dealkylation and disproportionation occurred simultaneously and independently of each other. The disproportionation/dealkylation ratio increased with decrease in temperature and/or an increase in cumene pressure. The dealkylation and disproportionation reactions followed a Langmuir-Hinshelwood model with inhibition by the reactant. The dealkylation has been interpreted in terms of a unimolecular surface reaction, while the disproportionation reaction in terms of a bimolecular surface reaction. The heat of adsorption of cumene and the entropy loss of cumene on adsorption were much larger for the dealkylation sites than for the disproportionation sites. These results indicated that dealkylation was catalyzed by strong acid sites, while disproportionation by weak acid sites. The dealkylation had a much higher activation energy than the disproportionation reaction. The activation energy for dealkylation (33.5 kcal mol−1) was in good agreement with that predicted on the assumption that the previously reported LFER (linear free-energy relationship) in the alcohol dehydration holds for alkylbenzene dealkylation.
Structure of a New Ionone Derivative, Nigakialcohol from Picrasma ailanthoides Planchon
Authors: Sugimoto Yayoi , Sakita Takaaki , Ikeda Toru , Moriyama Yoshihiko , Murae Tatsushi , Tsuyuki Takahiko , Takahashi Takeyoshi
Published: July 2006

A new ionone derivative, nigakialcohol, was isolated from the leaves of Picrasma ailanthoides  Planchon (Simaroubaceae), the structure being found to be (4R,5S)-4-[(R)-3-hydroxybutyl]-5-hydroxymethyl-3,3-dimethyl-1-cyclohexanone. Nigakilactones E, F, and H and vomifoliol were also isolated from the leaves.
The Transformation of 11-Deoxojervine into 18-Functional C-Nor-D-homosteroids
Authors: Suginome Hiroshi , Sato Norio , Masamune Tadashi
Published: July 2006

Deoxojervine, a C-nor-D-homosteroidal alkaloid, has been transformed into 17β-acetyl-12α-etiojervan-3β-ol acetate in 3 steps. Treatment with base gave the 17α-epimer. Reduction of the 17β-isomer with NaBH4 afforded 17β-ethyl-12α-etiojervane-3β,20β-diol 3-acetate as a single product whereas reduction of the 17α-isomer afforded 17β-ethyl-12α-etiojervane-3β,20β-diol 3-acetate and the 20α isomer in an approximate 1 : 1 ratio. Irradiation of 17β-ethyl-12α-etiojervane-3β,20β-diol 3-acetate in cyclohexane in the presence of lead tetraacetate and iodine afforded a C-18 functional C-nor-D-homosteroid as a 18,20-epoxide which was oxidized to the corresponding γ-lactone with chromium trioxide. A mixture of the 17α-ethyl-12α-etiojervane-3β,20α-diol 3-acetate and its 20β isomer in contrast gave no 18-functional compounds upon irradiation under similar conditions.
Aminosugars. XXXI. Preparation of Benzyl 2-Acylamino-4-azido-2,4-dideoxy-ribo- and -lyxopyranosides by Inversion of Hydroxyl Group on C-3
Authors: Hashimoto Hironobu , Araki Koichi , Yoshimura Juji
Published: July 2006

Benzyl 2-acylamino-4-azido-2,4-dideoxypentopyranosides having α-d-ribo, β-l-ribo, α-d-lyxo, and β-l-lyxo configurations were derived from the corresponding α-d-xylo, β-l-xylo, α-d-arabino, and β-l-arabino isomers, respectively, by inversion of hydroxyl group on C-3. Displacement reaction of sulfonyloxy group with sodium acetate or benzoate in aqueous 2-methoxyethanol or anhydrous N,N-dimethylformamide, or oxidation-reduction method via ulose derivative was used properly according to the stereochemistry of the starting materials.
Vapor-phase Hydrolysis of Chlorobenzene Catalyzed by Copper(II) Ion-exchanged Zirconium Phosphate
Authors: Izumi Yusuke , Mizutani Yukio
Published: July 2006

Copper(II) ion-exchanged zirconium phosphate (ZP–Cu(II)) effectively catalyzed the vapor-phase hydrolysis of chlorobenzene to phenol at 450 °C under atmospheric pressure. Per-pass conversion of chlorobenzene was between 12 and 18% with selectivity for phenol from 90 to 95 mol %. The catalytic activity was influenced by the content of copper, the ratio of phosphate to zirconium, and the pH at which copper(II) ions were introduced into zirconium phosphate. ZP–Cu(II) catalyst was amorphous and it turned inactive by thermal treatment at above 800 °C, resulting in a crystalline substance. The active site of ZP–Cu(II) for this hydrolysis reaction appears to be the phosphate groups of ZP bearing copper(II) ion. The reaction seems to proceed via a Rideal mechanism in which an adsorbed chlorobenzene molecule reacts with water in the vapor phase at the catalyst surface. The desorption of hydrogen chloride was rate controlling.
Theoretical Studies of Some Nonbenzenoid Hydrocarbons. V. Benzazulenes and Benzofluoranthenes
Authors: Das Gupta Archana , Chatterjee Subrata , Das Gupta Nanda K
Published: July 2006

The molecules benzazulenes and benzofluoranthenes have been studied by the semi-empirical method for π-molecular systems, similar to that of Pariser-Parr and Pople. Ground state properties and π*←π spectra have been predicted and compared with experiment. Agreement between the theoretical values and observed ones is good; that between the experimental value of half-wave reduction potential and values calculated by SCF(d) method is very good.
Thermochemistry of Copper(II) β-Diketonates, II. Bis(benzoylacetonato)copper(II)
Authors: Da Silva Manuel A V Ribeiro , Reis Ana Maria M V
Published: July 2006

The standard enthalpy of formation of crystalline bis(benzoylacetonato)copper(II) has been determined at 298.15 K by solution calorimetry: ΔHf°[Cu(bzac)2] (c)=−143.6±2.2 kcal mol−1. Enthalpy changes at 298.15 K for the following hypothetical gaseous reactions have been subsequently derived:

Cu(g)+2bzac·(g)=[Cu(bzac)2](g) ΔH=−165.9±14.3 kcal mol−1

Cu2+(g)+2bzac−(g)=[Cu(bzac)2](g) ΔH=−747.3±14.4 kcal mol−1

The corresponding homolytic(\barE) and heterolytic(\barE′) copper(II)-oxygen mean bond energy parameters were calculated as

\barECu-o=41±3 kcal mol−1 and \barE′Cu-o=187±3 kcal mol−1

respectively.
Reactions of 2-Ethoxycarbonyl-1,3-indandione with Aromatic Amines, Diazonium Salts, and Phenols
Authors: Afsah El-Sayed , Zimaity Tawfik
Published: July 2006

2-Ethoxycarbonyl-1,3-indandione (1) was treated with primary aromatic amines in acetic acid to afford 3-hydroxy-1-(arylimino) derivatives (2). Treatment of 1 with excess p-toluidine gave 3-tolylimino-4′-methyl-in-dancarboxanilide (3). With o− or p-phenylenediamine it yielded 3,3′-dihydroxy-1′-(o- or p-phenylenedinitrilo)di-2-indenecarboxylate. The tetraazacycloeicosene derivative was obtained by the action of p-phenylenediamine on 1 in a 1:1 molar ratio. In boiling toluene 1 gave the corresponding 2-carboxanilides (8) which cyclized to the diazepinone or to the quinolone. The coupling of 1 and 8 with diazonium salts was also investigated. The condensation of 1 with phenols afford 14, which were hydrolysed to 3-aryl-1-indenones.
A Synthetic Method for N-Benzyloxycarbonyl Hydroxy Amino Acid t-Butyl Esters
Authors: Kinoshita Hideki , Ishikawa Hajime , Kotake Hiroshi
Published: July 2006

A preparative method for the N-benzyloxycarbonyl hydroxy amino acid t-butyl esters using the aceto-acetyl group as a protecting group for the hydroxyl group of hydroxy amino acids is described. The acetoacetyl group is readily introduced into the hydroxyl group with diketene and effectively deprotected from the O-protected compounds using hydrazine.
Novel Lactonization of γ-Cyclopropyl Carboxylic Acid via Acid-catalyzed Cleavage of Cyclopropane Ring
Authors: Sekizaki Haruo , Ito Masaaki , Inoue Shoji
Published: July 2006

4,6,10,l0-Tetramethyltricyclo[4.4.0.01,3undec-4-ene-5-carboxylic acid has been converted to a tricyclic γ-butyrolactone by perchloric acid catalyzed isomerization. Acetalization of the ketocarboxylic acid afforded an acetal derivative of γ-butyrolactone.
Notiz über die Säurekatalysierte Umwandlung von 7a-Methyl-5,6,7,7a-tetrahydroindan-1,5-dion in 1-Methylbrexan-4,9-dion
Authors: Kobayashi Makoto , Minami Takashi , Matsumoto Takeshi
Published: July 2006

Beim Erhitzen in HCO2H mit Mineralsäure wurde 7a-Methyl-5,6,7,7a-tetrahydroindan-1,5-dion sauer katalysiert in 1-Methylbrexan-4,9-dion umgewandelt. Ein Zwischenprodukt, 7a-Methylhexahydro-2-inden-1,5-dion konnte gaschromatographisch abgetrennt werden.
Enantioselective Alkylation Using Optically Active Phase Transfer Catalyst
Authors: Saigo Kazuhiko , Koda Hiroshi , Nohira Hiroyuki
Published: July 2006

Synthesis of optically active benzyl[cis-2-(hydroxymethyl)cyclohexyl]dimethylammonium bromide (3) and its application to asymmetric synthesis were studied. It was found that 3 was as effective as (−)-N-benzyl-N-methylephedrinium bromide in the enantioselective alkylation of active methylene compounds when it was employed as a chiral phase transfer catalyst.
Methylation of Purine 2′-Deoxynucleosides with Trimethyl Phosphate
Authors: Tanabe Toshizumi , Yamauchi Kiyoshi , Kinoshita Masayoshi
Published: July 2006

Trimethyl phosphate was found to methylate deoxyadenosine (N-1) and deoxyguanosine (N-1, N-7, and O-6) in a homogeneous aqueous phase at 37 and 60 °C, giving the corresponding methyl derivatives.
Mesomorphic 4-Alkylphenyl 4-Benzoyloxybenzoate Bearing a Terminal Vinyl Group
Authors: Kamogawa Hiroyoshi , Sekigawa Masayuki , Nakano Tomohiro , Izawa Shin , Nanasawa Masato
Published: July 2006

4-Alkylphenyl 4-(4-vinyl-, methacryloyloxy-, and methacrylamido-benzoyloxy)benzoates have been synthesized by the reactions of 4-alkylphenyl 4-hydroxybenzoates with the corresponding substituted benzoyl chloride in pyridine. The mesomorphic ranges of these novel monomers are highly dependent upon the type of substituent at both ends of the molecules.
A New Triterpene Glucoside from Terminalia arjuna. Arjunglucoside III
Authors: Tsuyuki Takahiko , Hamada Yuriko , Honda Tadashi , Takahashi Takeyoshi , Matsushita Kazuhiro
Published: July 2006

The structure of a new triterpene glucoside, arjunglucoside III, isolated from Terminalia arjuna was found to be β-d-glucopyranosyl 2α,3β,19α-trihydroxy-11-oxoolean-12-en-28-oate.
Adsorption of Water on FeOOH as Studied by Electrical Conductivity Measurements
Authors: Kaneko Katsumi , Inouye Katsuya
Published: July 2006

Changes in the electrical conductivity of synthetic α-, β-, and γ-FeOOH crystals with the amount of adsorbed water were measured at 30 °C and various frequencies (dc, 100–10 MHz). The conductivity variations of wateradsorbed FeOOH with temperature were also examined over the range from −140 to 140 °C. For the adsorption coverages between 0 and 0.5, the electronic conduction increased with the coverage due to the transfer of electrons from chemisorbed water molecules to the FeOOH crystal. The decrease in activation energy for conduction with chemisorption was observed. The conductivity increase due to the chemisorption is related to the characteristic surface structure of each FeOOH polymorph. In the coverage range 0.7–2, protons in the adsorbed water layer transport electrical charges. The linear relationships between the logarithm of conductivity and the logarithm of the relative pressure of water vapor suggest the presence of clusters of physisorbed water molecules on FeOOH surfaces. A steep change in protonic conductivity by a factor of 102–104 was observed at a temperature close to −5 °C. The change seems to be caused by an order-disorder transition of protons in the adsorbed water layer.
ESR Study of SeO2− Radical in an Irradiated Single Crystal of Triglycine Selenate in the Vicinity of Phase Transition Temperature
Authors: Kotake Yashige , Kuwata Keiji
Published: July 2006

Detailed observations of the angular dependence of ESR spectra of SeO2− radicals formed by X-ray irradiation of a single crystal of ferroelectric triglycine selenate were carried out. Two kinds of SeO2− radicals were produced due to the difference in manner of selenium-oxygen bond scission. In spite of the difference in stability of radicals in TGSe and those in TGS, the behavior of SeO2− radicals in the phase transition region is in line with that expected from the result of X-ray diffraction study of TGS.
Ab initio LCAO MO SCF CI Calculations on the Electronic Structure of the Cyclopropenyl Cation
Authors: Takada Toshikazu , Ohno Kimio
Published: July 2006

Ab initio LCAO MO SCF and limited CI calculations are carried out on the electronic structure of the C3H3+ ion. Two kinds of basis sets are used, namely the minimal STO’s and the minimal STO’s plus 3d orbitals on each carbon atom. With the latter basis, the equilibrium C–C distance is calculated to be 1.389 Å. It is predicted that the C–C bond distance of C3H3+ is shorter than that of C6H6. The calculated C–C stretching force constant is 7.92 mdyn/Å and is close to the experimental value 6.59 mdyn/Å. Contour diagrams of the charge distribution of valence electrons are drawn and it is revealed that the calculated C–C bonds are bent and have two maxima in charge density. In terms of population analysis of localized MO’s, it is shown that the C–H bond in this molecule has a higher s-character than the C–H bonds in C2H4 and C6H6 and is close to an sp hybrid. This is in accord with a very large NMR coupling constant J13C–H. From CI calculations of low lying excited states, singlet σ-π* states (1A1″, 1E″, 1A2″) are calculated to be lower than the singlet π-π* state (1E′).
Molecular Motion in Ammonium Hydrogendifluoride Studied by Pulsed NMR
Authors: Furukawa Yoshihiro , Kiriyama Hideko
Published: July 2006

The proton and fluorine-19 spin-lattice relaxation times, T1 and T1ρ, in polycrystalline ammonium hydrogendifluoride were measured in the temperature range 142–345 K to elucidate the molecular motion of cation and anion. Below 200 K, the relaxation rates of both nuclei can be accounted for by dipolar interactions modulated via the isotropic reorientation of NH4+ ions. The logT1ρ  versus 1/T curves above 200 K exhibit two distinct minima, suggesting that two crystallographically nonequivalent HF2− ions undergo 180°-flips about their two-fold axes with different correlation times. The activation energy of the NH4+ reorientation was determined to be 25.5±1.0 kJ/mol from the T1 data, while those of the 180°-flips were estimated from the T1ρ data to be about 40 and 60 kJ/mol for the two types of anions. These relaxation mechanisms have been confirmed by further experiments on a partially deuterated sample.
The Stereoisomerization of N,N′-Diacyl Derivatives of Indigo
Authors: Omote Yoshimori , Imada Satoshi , Matsuzaki Ryuichi , Fujiki Kiyoko , Nishio Takehiko , Kashima Choji
Published: July 2006

The cis-isomers of N,N′-diacylindigo (e.g., cis-N,N′-diacetyl-, distearoyl-, dibenzoyl-, and bis(3,5-dinitrobenzoyl)-indigo) were found to separate out in a crystalline form from a solution of the corresponding trans-isomer upon irradiation. The kinetics of the cis-to-trans isomerization of these four cis-N,N′-diacylindigos was studied, the relative rates being 7.9, 11.0, 1.0, and 5.1 respectively. Several amines were found to accelerate the cis-to-trans isomerization in the order of: Et2NH>PrNH2>Et3N>i-Pr2NH in the case of cis-N,N′-diacetylindigo and in the order of: Et2NH>i-Pr2NH>PrNH2>Et3N in the case of cis-N,N′-dibenzoylindigo.
A Novel Carbonization of Naphthalene and Other Aromatic Compounds in a Molten Mixture of AlCl3–NaCl–KCl
Authors: Ota Etsuro , Inoue Sadao , Horiguchi Masahiro , Otani Sugio
Published: July 2006

The use of molten salt as the solvent made it possible to carry out the carbonization process throughout in the liquid state. The process proceeded at a lower temperature than conventional ones, resulting in higher yields. The carbon was deposited from the reaction mixture as powder or flakes; it was similar to “raw coke” in its composition. Thus, 12.8 g of naphthalene was treated in a mixed melt (mp 95 °C) of AlCl3, NaCl, and KCl (60:26:14 mol%) at 300 °C for 10 h, yielding 11.3 g of carbon. Anthracene, phenanthrene, substituted naphthalene, and biphenyl also gave carbon in yields 69–99% of the theoretical yields, while N-containing heterocycles hardly reacted at all. The X-ray parameters of the carbons, the d002 spacing and the crystal thickness, Lc, varied with the kind of compound used and with other factors; after heat-treatment at 2800 °C, these values were 3.37–3.52 and 20–700 Å respectively. As the mode of reaction, an acid-catalyzed ionic mechanism was proposed, and the role of hydrogen-disproportionation was discussed.
Bis(N-acetyl-Dl-leucinate)copper(II) Complexes and Their Amine Adducts
Authors: Marcotrigiano G , Menabue L , Morini P , Pellacani G C
Published: July 2006

A compound of the type Cu(AcLeu)2 and its amine adducts of the type Cu(AcLeu)2Bn (AcLeu=N-acetyl-Dl-leucinato ion; n=2 and B=pyridine, 3- and 4-methylpyridine, N-methylpiperazine, morpholine, and piperidine; n=1 and B=1,10-phenanthroline, 2,2′-bipyridyl, piperazine, and pyridazine) were prepared and investigated by means of electronic, infrared and EPR spectroscopy and magnetic moment measurements. The results suggest a tetragonal configuration for the Cu(AcLeu)2 complex and the amine adducts with CuO4 and CuO2N2 chromophores, respectively. For the green Cu(AcLeu)2·pid complex a binuclear configuration similar to that observed for the bis(acetato)copper(II) monohydrate complex is suggested. The amino acid in all the complexes is found to coordinate toward the carboxylato group. In the assignment of the way in which the carboxylato group coordinates, in addition to the difference between their antisymmetric and symmetric stretching frequencies, we also pay special attention to the position of the symmetric stretch, which is directly connected with the oxygen atom linked to the metal ion.
Vibrational Spectra and Rotational Isomerism of 2-Chloro-and 2-Bromoethyl Methyl Sulfides
Authors: Matsuura Hiroatsu , Miyauchi Nobuyuki , Murata Hiromu , Sakakibara Masaaki
Published: July 2006

The Raman and infrared spectra of 2-chloro- and 2-bromoethyl methyl sulfides CH3SCH2CH2X (X=Cl and Br) were measured for the liquid and crystalline solid states. The vibrational frequencies of these molecules were calculated by the use of the force constants transferred from unbranched alkyl sulfides and alkyl halides. The rotational isomerism was studied on the basis of the spectral observations and the calculations, and the following conclusions were obtained. (1) In the crystalline solid state, both the chloride and the bromide take the molecular form with the gauche conformation about the (C)S–C(C) axis and the trans conformation about the (S)C–C(X) axis. (2) In addition to this form (GT), three other forms (TG, GG, and TT) coexist in the liquid state, the GT form being the most stable. (3) The sulfur atom is suggested to lower the energy of the trans conformation of the (S)C–C(X) axis.
Polarized Two-photon Absorption Spectra of Naphthalene in Durene Single Crystal with Two Synchronized Tunable Dye Lasers
Authors: Mikami Naohiko , Hong Hwai-Kwan
Published: July 2006

Polarized two-photon absorption spectra of naphthalene in a single crystal of durene were observed with one and two beams of tunable dye lasers. Diagonal elements of the two-photon transition tensor were determined by one beam experiments with different incident polarizations on different faces of an oriented single crystal. The off-diagonal elements of the two-photon transition tensor were determined with two synchronized beams of different wavelengths and polarizations on the same sample. It was found that most of the vibronic states have large σLL consistent with an overall vibronic Ag symmetry and a long axis polarized 1B2u intermediate state. The intermediate states of the two-photon process of the strongest vibronic origin have been discussed on the basis of the observed values of the two-photon transition tensor elements. The band also has a small but non-vanishing off-diagonal tensor element (σLM). A crystal field perturbation due to reduced site symmetry by a B3g two-photon allowed state is postulated.
Pressure and Solvent Shifts of Charge Transfer Absorption Band of Iodine Complexes
Authors: Sawamura Seiji , Taniguchi Yoshihiro , Suzuki Keizo
Published: July 2006

Absorption spectra of the CT band of I2 complexes were observed in several nonpolar solvents at 1 bar, and in heptane up to 4400 bar. All solvent shifts were red with an increase in (n2−1)/(2n2+1), the refractive index (n) function of solvents, consistent with the solvent shift theory. On the other hand pressure caused a variety of shifts, that is, red shifts in benzene–, toluene–, and mesitylene–I2 complexes, an inversion shift from red to blue in HMB–I2 complex, and blue shifts in Et3N–, n-Pr3N–, and n-Bu3N-I2 complexes, though increase in pressure invariably raises the (n2−1)(2n2+1) value of solvent. The pressure shifts of I2 complexes seem to be interpreted by a sum of two effects. One is the increased polarity of the solvent, which causes a red shift. The other is the decrease in the bond distance between a donor and an acceptor, which contributes to a blue shift in a strong CT complex and to a red shift in a week one. The pressure and solvent shifts of I2 complexes were compared with those of π-donor–TCNE complexes.
Rotational Isomerism in Fluorene Derivatives. III. The Conformation of 9-(9-Fluorenyl)-9-(2-substituted 9-fluorenyl)fluorene Derivatives
Authors: Kajigaeshi Shoji , Fujisaki Shizuo , Aizu Ichishi , Hara Hiroshi
Published: July 2006

The conformations of 9,9-di(9-fluorenyl)fluorene derivatives (1) with substituents at the 2- or 2,7-positions in a terminal fluorene ring were illustrated by the gauche-gauche forms at room temperature. DNMR studies of 1 gave the values of about 85–88 kJ/mol for the free energy of activation (ΔG\eweq) for the restricted rotation around the C(9)–C(9) bonds. The conformation of 9,9-di(9-fluorenyl) fluorene, the parent compound of 1, was also shown to the only gauche-gauche (+sc, +sc or −sc, −sc) form at room temperature.