bluuebunny/crossref_metadata_2025 huggingface dataset:
The Dissociative Excitation and Dissociative Ionization of Simple Aliphatic Hydrocarbons by Controlled Electron Impact
Authors: Tsuji Masaharu , Ogawa Teiichiro , Nishimura Yukio , Ishibashi Nobuhiko
Published: July 2006

Photoemissions from the following excited species were observed from simple aliphatic hydrocarbons (CH4, C2H2, C2H4, 1,3-C4H6) under controlled electron-impact excitation (0–400 eV) at wavelengths from 300 to 600 nm: H(Balmer), CH(A–X, B–X, C–X), CH+(A–X, B–A, b–a), C2(C–A, d–a; not from CH4), and C4H2+(A–X; not from CH4). All the excited species except for C4H2+ from C2H2 and C2H4 were confirmed to be primarily produced. The excitation function (0–400 eV) and the appearance potential of H, CH, and CH+ produced from CH4 and C2H2 were measured, and the corresponding processes of the fragmentation near the threshold were determined. The CH4+e→CH+(B)+H2(X)+H(n=1) and C2H2+e→CH+(B)+CH(X) processes were concluded to be responsible for the formation of CH+(B). The formation of ionic species, H+ and CH+, can be considered as the limiting case of the dissociative excitation for producing H and CH. A triplet excitation process may contribute to the formation of CH(A) from C2H2. The observed threshold energies indicated that superexcited states were involved in the formation of excited neutral fragment species.
Dehydroannulenes. I. Synthesis and Properties of 1,5,10,14-Tetramethyl-6,8,15,17-tetrakisdehydro[18]annulene
Authors: Ojima J\={u}ro , Katakami Tsutomu , Nakaminami Gen , Nakagawa Masazumi
Published: July 2006

1,6,10,15-Tetramethyl-7,9,15,17-cyclooctadecatetraene-2,4,11,13-tetrayne-1,6-diol (VII), a 18-membered cyclic glycol, was synthesized by a stepwise reaction sequence starting from 3-methyl-2-penten-4-ynal (III). Treatment of the cyclic glycol (VII) with stannous chloride dihydrate in concentrated hydrochloric acid yielded tetramethyltetrakisdehydro[18]annulene (VIII). Examination of the NMR spectra clearly indicates that the tetrakisdehydro[18]annulene (VIII) containing formal diacetylene and hexapentaene units sustains a strong diamagnetic ring current and has a high conformational stability.
Carbon Monoxide Oxidation over Chromium Sesquioxide. II. Adsorption Behavior of CO and CO2
Authors: Kobayashi Masayoshi , Date Tomoyuki , Kobayashi Haruo
Published: July 2006

The adsorption behavior of carbon monoxide and carbon dioxide on oxidized and reduced surface of α-Cr2O3 catalyst was studied experimentally by the application of a transient response method. From the analysis of response curves obtained for the concentration of effluent gas component and for the electrical conductivity of catalysts, it was shown that neither carbon monoxide nor carbon dioxide can be adsorbed on the oxidized surface, but they are adsorbed on the reduced surface without electron transfer between adsorbates and the catalysts. Adsorption of carbon monoxide is almost reversible, but that of carbon dioxide is both reversible and irreversible. Oxygen markedly accelerates the desorption of both carbon monoxide and carbon dioxide. It is concluded that this can be attributed to the effect of adsorbed oxygen in lowering the degree of coordinative unsaturation of Cr3+ ions.
Effects of the Anion on the Extraction of Cobalt with 8-Quinolinol into Chloroform
Authors: Sekido Eiichi , Fujita Kazuhiko
Published: July 2006

The effects of the anions, especially the perchlorate ion, on the extraction of cobalt into chloroform with 8-quinolinol (Hql) were examined. Two kinds of cobalt(II) 8-quinolinol complexes, species A and B, are extracted into the chloroform phase from the aqueous cobalt(II) solution containing perchlorate ions. Species A contains no perchlorate ion and is extracted above pH 7.7; species B is an ion-pair complex containing a perchlorate ion and is predominantly extracted below pH 5.1. The compositions of species A and B were estimated to be Co2ql4(Hql)2 and Co2ql3(Hql)3ClO4, respectively. These dimer complexes are related by the following equilibrium, with logKAB=−7.2:

[Co_2ql_3(Hql)_3]^+ClO_4(o)^-\ightleftarrowsCo_2ql_4(Hql)_2(o)+ClO_4^-+H^+

The species extracted into the chloroform phase from the aqueous cobalt(II) solution containing sulfate ions does not contain any sulfate ions. The formation of the species containing anions increases in the order: ClO4−>NO3−>Cl−>So42−, which is also the general order of the extent of forming the ion-pair compounds. The ion-pair complex tends to prevent the oxidation from cobalt(II) 8-quinolinol complex to cobalt(III) 8-quinolinol complex.
Keto-Enol Tautomerism. I. The Calorimetrical Determination of the Equilibrium Constant for Keto-Enol Tautomerism for Cyclopentanone
Authors: Hine Jack , Arata Kazushi
Published: July 2006

The enol content of cyclopentanone was determined by calorimetrical measurement of the enthalpy of hydrolysis of cyclopentenyl methyl ether to cyclopentanone with the assumption that the thermodynamics of hydrolysis of any ROMe to ROH is the same as that for any other ROMe. The enthalpy of the ketonization of cyclopentenol was determined to be −7.87 kcal/mol in the liquid phase and −11.66 kcal/mol in the gas phase, at 25 °C. The enol content of cyclopentanone in the gas phase at 25 °C was found to be 2.5×10−7%
Keto-Enol Tautomerism. II. The Calorimetrical Determination of the Equilibrium Constants for Keto-Enol Tautomerism for Cyclohexanone and Acetone
Authors: Hine Jack , Arata Kazushi
Published: July 2006

The vapor phase enol contents of cyclohexanone and acetone were determined by calorimetric measurements of the enthalpies of hydrolysis of their corresponding enol methyl ethers to ketones and methanol in 91.67% THF–H2O (0.15 M H2SO4). The relative order of enol content, together with cyclopentanone in our previous study, was cyclohexanone>cyclopentanone≥ acetone, which was the same as that reported by Gero and by Schwarzenbach, but different from Bell’s observed order (cyclopentanone>cyclohexanone>acetone). The enthalpies calculated from Benson’s correlation of thermodynamic properties for the enolization reactions of these ketones and for the hydrolysis reactions of enol methyl ethers agreed with our relative ordering. Furthermore, data on reactions of compounds with 5- and 6-membered rings lead to the prediction that cyclohexanone contains more enol than cyclopentanone does. The kinetics of hydrolysis of enol methyl ethers was also discussed.
The Thermal Decomposition of N-Thiocarbonyl Diphenylsulfimides
Authors: Yoshida Hiroshi , Taketani Hitoshi , Ogata Tsuyoshi , Inokawa Saburo
Published: July 2006

N-Thiocarbonyl diphenylsulfimides, Ia–i (R=Ph, p- and m-MeC6H4, p- and m-MeOC6H4, MeO, EtO, MeNH, and Me2N), were prepared, and their thermal decomposition were studied. At 70 °C, Ia–h decomposed easily to give nitriles (or their derivatives), together with diphenyl sulfide and sulfur. Contrary to these results, the oxygen analog of Ia, g showed no decomposition even upon heating at 140 °C. The thermolysis of Ia–e in the presence of excess acetylenes (III) gave isothiazoles(IV) in moderate yields. Thiazirine(V) and nitrile sulfide(VI) may be supposed, on the basis of the kinetic experiments, to be possible intermediates for the thermal decomposition of Ib–e.
Biogenetic Model Reactions of Epoxygermacrones
Authors: Niwa Masatake , Iguchi Masanobu , Yamamura Shosuke
Published: July 2006

From a biogenetic point of view, acid- or base-catalyzed cyclizations of epoxygermacrones (2, 23, and 33) were carried out. In most cases, the stereospecific cyclizations of these epoxygermacrones took place to give many compounds with an 11-oxabicyclo[5.3.1]undecane system, cadinane-type, selinane-type or guaiane-type compounds depending on the kinds of reagents and solvents. The formation process of each cyclization product will be discussed in detail.
Regio- and Stereospecific Cyclizations of Germacrones
Authors: Niwa Masatake , Iguchi Masanobu , Yamamura Shosuke
Published: July 2006

From a biogenetic point of view, the acid-catalyzed cyclizations of germacrones (1, 2, and 3) were carried out, using several kinds of reagents and solvents (80% aq AcOH, 80% aq HCOOH, AlCl3 in absolute ether, AcOH in PhSH, 100% HCOOH in PhSH, and concd H2SO4 in PhSH). In all cases, the stereospecific cyclizations of these germacrones took place to give cadinane-type, selinane-type or guaiane-type compounds depending on the kinds of reagents and solvents. The formation process of each compound will be presented in detail.
A Single-step Synthesis of 2-Substituted 2-Thiazolines
Authors: Suzuki Nobutaka , Izawa Yasuji
Published: July 2006

2-Phenyl-2-thiazoline (4b) and its derivatives: [4-carboxylic acid (4c), 4-carboxylic acid methyl ester (4d), and 5,5-dimethyl-4-carboxylic acid (4e)], 2-(p-chlorophenyl)-2-thiazoline (4f) and its 4-carboxylic acid (4g), and 2-methyl-2-thiazoline (4h) were obtained by treating RCS2CH2CO2H [R=Phenyl (1b), p-chlorophenyl (Id), or methyl (1e)] or MeCS2Et (1f) with the corresponding 2-aminoethane thiols, i.e., cysteamine (6a), cysteine (6b), cysteine methy ester (6c), and/or penicillamine (6d). 4b was also obtained from PhCS2Et (1c) and 6a with a rate approximately equal to that from 1b and 6a. The attempted synthesis of 2-methyl-2-thiazoline-4-carboxylic acid (4i) using a similar method gave only N-acetylcysteine (7).
The Wolff Rearrangement and 1,3-Dipolar Cycloaddition of 2-Diazo-3,4-bis(diphenylmethylene)cyclobutanone
Authors: Ueda Kozaburo , Igaki Masanori , Toda Fumio
Published: July 2006

The first example of the Wolff rearrangement of α-diazocyclobutanone, the title diazo ketone (2), into the three-membered cyclic ketene (4) was observed. The ketene intermediate (4) could be trapped by its reaction with alcohols, aniline, azobenzene, and N-benzylideneaniline to afford 1-alkoxycarbonyl- (5a–c) and 1-phenylcarbamoyl-2,3-bis(diphenylmethylene)cyclopropane (5e), and 1,2-bis(diphenylmethylene)-5,6-diphenyl-5,6-diaza-(9) and 1,2-bis(diphenylmethylene)-5,6-diphenyl-5-azaspiro[2,3]hexan-4-one (10a), respectively. In contrast to the rearrangement, 2 directly reacted with p-benzoquinone and nitrosobenzene, affording the corresponding 1,3-dipolar cycloadducts (14 and 15).
The Lanthanoid-Induced Shifts of Proton NMR Spectra and the Conformations of β-(2-Thienyl)acrylic Esters and Related Compounds
Authors: Hirota Minoru , Yoshida Shigeko , Nagawa Yoshinobu , Ono Makoto , Endo Hiroko , Satonaka Hajime
Published: July 2006

The most predominant conformation of 4-(2-thienyl)-3-butene-2-one and methyl β-(2-thienyl)acrylates were determined by the analysis of their LIS’s. The LIS’s toward higher fields were observed with some ring protons (H3’s and some of H4’s), and were best interpreted by assuming that about 20% of the shift reagent coordinates on the methoxyl oxygen atom and the rest on the carbonyl oxygen atom.
Layered Compounds. XXXVI. Structure and Properties of Triple-layered Metaparacyclophanes
Authors: Kannen Naoki , Otsubo Tetsuo , Sakata Yoshiteru , Misumi Soichi
Published: July 2006

The geometrical structures of triple-layered metaparacyclophanes are discussed on the basis of the chemical shifts of the NMR spectra and their temperature dependence. [2.2]Metacyclo(4,7)[2.2]paracyclophane 1 and [2.2]metacyclo(12,15)[2.2]metaparacyclophane 2 proved to be mixtures of conformational isomers due to arrangement of meta-substituted ring. [2.2]Paracyclo(4,6)[2.2]metaparacyclophane 3 was confirmed to be a staircase-shape (anti-form), in contrast to a platform-shape (syn-form) of [2.2]metacyclo(4,6)[2.2]metaparacyclophane 5. In their electronic spectra, 1 and 2 exhibit a transannular electronic interaction between the benzene rings similar to that of multilayered [2.2]paracyclophanes; 3 and 5 show one similar to that of multilayered [2.2]metacyclo-phanes. The difference between the former and the latter groups seems to arise from the substitution modes of methylene bridges attached to the inside benzene of triple-layered metaparacyclophanes.
Layered Compounds. XXXV. Syntheses of Triple-layered Metaparacyclophanes
Authors: Kannen Naoki , Otsubo Tetsuo , Sakata Yoshiteru , Misumi Soichi
Published: July 2006

Six triple-layered [2.2]metaparacyclophanes have been prepared using general synthetic methods such as the Stevens rearrangement-Raney nickel desulfurization method, pyrolysis of bissulfone, and photo-induced desulfurization. The pyrolysis of bissulfone has turned out to be the most useful and convenient method for preparation of the intermediate double-layered [2.2]metaparacyclophanes because of simple experimental process and excellent yields. The unexpected formation of compound 9 during the photo-induced desulfurization of 7 was explained by a unique skeletal rearrangement of the intermediate 8 on irradiation.
The Alkoxylation of Aerosil Silica with C1–C4 Alcohols
Authors: Kitahara Shigeto
Published: July 2006

The Aerosil surface was treated with C1–C4 alcohols under both high-pressure and low-pressure conditions. The high-pressure treatment was carried out at various temperatures up to 250 °C using an autoclave, while the low-pressure treatment was done at 280 °C under vapor pressure at room temperature. The surface changes were followed by IR spectroscopy, and the carbon content was determined. The degrees of alkoxylation (OR groups/100 Å2) of the Aerosils treated sufficiently under low pressures were 1.3–1.6, approximately equal to the amount of OH isolated before the treatment, while the values under high pressures reached 2.3–3.4, equal or near to the amount of the total OH. The values for methoxylation were particularly higher, while those for t-butoxylation were quite low. These results, in addition to the observation of the IR spectra, indicate that the isolated OH groups are predominantly esterified under low pressures, while under high pressures the vicinal OH groups are esterified as well, and the opening of the siloxane bonds occurs easily in the case of methoxylation. The stability of the alkyl groups on the Aerosil against heating decreased in the order of: primary>secondary>tertiary.
Spectroscopic Study of Alkyl Vinyl Ketones
Authors: Naito Ikuo , Kinoshita Akihiro , Yonemitsu Tadashi
Published: July 2006

Alkyl vinyl ketones have two conformations, s-cis and s-trans. The ratios of the two conformers are given by comparing their IR with NMR data. The conformer of s-cis is given by the equation, Percentage of s-cis=180. (Δδ−0.15) (%), where Δδ is the chemical shift difference between cis and trans protons for carbonyl group. The value of ΔF obtained by means of the equation is related to steric factors Esc of bearing alkyl groups. The ratio s-cis/s-trans is determined by the bulkiness of the alkyl group.
The Effect of Organic Additives on the Thermodynamic Parameters of Micellization
Authors: Miyagishi Shigeyoshi
Published: July 2006

The CMC values of dodecylammonium chloride and iodide and of hexadecylammonium chloride were measured in water upon the addition of acetone, 1-propanol, and urea at several temperatures. The effects of the additives were most remarkable on the CMC of hexadecylammonium chloride at 45.0 °C. Urea was less effective on the disruption of micelles than acetone, while the addition of 1-propanol was most effective. The enthalpy of micellization became more negative, while the entropy of micellization became less positive, as the additive concentration increased. We divided the standard free energy of micellization into the hydrophobic term, ΔG°n, and the hydrophilic term, ΔG°p. The value of ΔG°p became more negative with the additive concentration and contributed to the stabilization of the micelle, while ΔG°n became less negative. Therefore, it was concluded that the disruption of the micelle in the presence of these organic additives results from an increase in the free energy in the hydrophobic group of the surfactant molecule.
A pH and pNa Study of Aqueous Solutions of Sodium Deoxycholate
Authors: Sugihara Gohsuke , Tanaka Mitsuru
Published: July 2006

The pH and pNa of aqueous solutions of sodium deoxycholate (SDC) were measured at various temperatures. The critical micelle concentrations (CMC) were determined by means of the crooked points on the plot of pH or pNa vs. the SDC concentration. The data obtained were interpreted thermodynamically, and changes in the enthalpy and entropy of micellization were evaluated, from which it was concluded that the hydrogen bond plays a very important role in the micelle formation.
The Approximate Self-Consistent Renormalized RPA: The Electronic Excited States of DNA Bases in the CNDO/S Method
Authors: Ito Hirotoshi , I’Haya Yasumasa J
Published: July 2006

Comments are given upon the approximate self-consistent renormalized RPA(SCrRPA) presented in our previous papar which assumes the correlated ground state wavefunction to be the linear combination of the Hartree-Fock ground state and doubly excited states, in the CI language. The rationalization of the approximate SCrRPA is made from the results computed by the complete SCrRPA, whose recipe is simply made. Finally, a numerical comparison of the several RPA methods is made as to the electronic spectra of four DNA bases by using the CNDO/S method.
Complexes between Nucleotide Base and Amino Acid. II. Crystal Structure of 5-Bromocytosine : N-Tosyl-l-glutamic Acid
Authors: Ohki Minoru , Takenaka Akio , Shimanouchi Hirotaka , Sasada Yoshio
Published: July 2006

The complex crystals of 5-bromocytosine and N-tosyl-l-glutamic acid were obtained from their aqueous solution. The space group is P1 with dimensions of a=10.843(1), b=11.690(2), c=10.879(2) Å, α=122.15(1), β=121.38(1), γ=69.93(1)°, and Z=2. The structure was solved by the heavy atom method and refined by a block-diagonal least-squares method. The undissociated γ-carboxyl group of glutamic acid is bound with O(2) and N(4) of 5-bromocytosine through hydrogen bonds. This interaction mode is different from those found in some cytosine : glycine complexes and cytidine : N-benzyloxycarbonyl-l-glutamic acid complex dihydrate in which the dissociated α-carboxyl group plays a role. This is the first example of interaction between cytosine and the acidic side group of amino acid.
A Single-step Synthesis of 2-Substituted Benzo-azoles
Authors: Suzuki Nobutaka , Yamabayashi Toshiyuki , Izawa Yasuji
Published: July 2006

2-Substituted benzimidazoles (3a and 5a), benzothiazoles (3b and 5b), and benzoxazole (3c) are readily synthesized in good yields by treating (thiobenzoylthio)acetic acid (1) or ethyl dithioacetate (4) with the corresponding o-substituted anilines (2a, 2b, and 2c) in slightly alkaline media at room temperature.
1,3-Benzodithiolylium Salts. Synthesis and Reactions with Nucleophilic Reagents
Authors: Nakayama Jyuzo , Fujiwara Kazuo , Hoshino Masamatsu
Published: July 2006

Various salts of 1,3-benzodithiolylium ion were prepared in excellent yields on treatment of 2-alkoxy- and 2-alkylthio-1,3-benzodithioles with acids in acetic anhydride. The reactions of 1,3-benzodithiolylium tetrafluoroborate (1a) with a wide variety of nucleophilic reagents (alcohols, water, thiols, hydrogen sulfide, primary, secondary, and tertiary amines, ammonia, N,N-dimethylformamide, electron-rich aromatic compounds, active methylene compounds, tropilidene, and sodium borohydride) were studied. In all cases examined, 1a reacted with nucleophilic reagents at the 2-position to give the corresponding 1,3-benzodithioles in good yields, excepting the reactions with tertiary amines and N,N-dimethylformamide which resulted in the formation of dibenzotetrathiafulvalene. Salt 1a was also prepared from 1,3-benzodithiole and trityl tetrafluoroborate.
The Formation and Dissociation of the Solvated Ion-pair in the Excited Pyrene–Dicyanobenzene System
Authors: Hino Tetsuro , Masuhara Hiroshi , Mataga Noboru
Published: July 2006

Nanosecond laser photolysis has been applied to investigate the photochemical primary processes of the pyrene-p-dicyanobenzene system in some solvents. The solvated ion-pair is formed by the excitation and its yield increases as the dielectric constant of the solvent does; this was explained with the empirical equation proposed previously. The dissociation of the solvated ion-pair to free ions was directly observed in moderately polar solvents and the rate constant of the dissociation was determined, which is in agreement with the values calculated by Eigen’s equation. The role of the ion-pair formation in the fluorescence quenching was discussed on the basis of the present results, and it was concluded that some unknown quenching processes other than the triplet formation compete with the solvation to ion-pairs.
Electronic Spectra of Perylene and Coronene Evaporated Films as a Function of Their Crystallinity
Authors: Kamura Yusuke , Shirotani Ichimin , Ohno Koichi , Seki Kazuhiko , Inokuchi Hiroo
Published: July 2006

The absorption spectra of evaporated thin films of perylene and coronene have been studied as a function of their crystallinity. The amorphous films deposited on a low-temperature substrate in vacuo gave rise to “molecular” spectra which are very different from those of the polycrystalline films. The absorption spectra of amorphous films gradually changed with an increase in the substrate temperature to become similar to those of the polycrystalline films.
Metal Complexes of EDTA and Its Related Compounds. II. Geometric Isomers of [Co(X)(trimethylenediamine-N,N,N′-triacetate)] Complexes with X=H2O, NH3, Cl−, and CN−
Authors: Doh Myung-Ki , Ogino Hiroshi , Fujita Junnosuke , Saito Kazuo
Published: July 2006

Three geometric isomers, equatorial-skew, polar-chair and polar-skew, of [Co(X)(trdtra)] (trdtra3−=trimethylenediamine-N,N,N′-triacetate) have been prepared for each X=H2O, NH3 and Cl−, and the structures assigned mainly by comparing their electronic spectra with those of the equatorial-skew and the polar-chair isomers of N-methyl-trdtra complexes reported previously. The cyano complex gives only the polar-chair isomer.
Stereoselective and Stereospecific Reactions. III. Benzoylation, Cyclfzation, and Epimerization of Diols
Authors: Mitsunobu Oyo , Kimura Junji , Iiizumi Ken-ichi , Yanagida Noboru
Published: July 2006

The benzoylation of various classes of diols by means of diethyl azodicarboxylate (1) and triphenylphosphine (2) was carried out at room temperature. When primary–secondary diols were treated with an equimolar amount of benzoic acid (3) in the presence of 1.5 molar equivalents of 1 and 2, reaction mainly Occurred at their primary hydroxyl functions. Secondary–secondary diols gave mono- and dibenzoylated products or cyclic ethers. The course of the reactions depends on the structure of diols used. Thus, intermolecular displacement giving benzoates is a favorable process for 1,3-butanediol, 2,4-pentanediol and trans-1,2-indanediol, while 2,5-hexanediol and trans-1,2-cyclohexanediol afford the cyclized products.
Photochemical Ligand Substitution in Hexakis(aryl isocyanide)chromium(0)–Olefin Systems
Authors: Iuchi Kazuhito , Asada Shintaro , Kinugasa Takashi , Kanamori Koji , Sugimori Akira
Published: July 2006

Isocyanide chromium(0) complexes coordinated by dimethyl fumarate, fumaronitrile and maleic anhydride were prepared photochemically by the irradiation of hexakis(aryl isocyanide)chromium(0) with the corresponding olefin. Tetracyanoethylene reacts with hexakis(aryl isocyanide)chromium(0) thermally without illumination, while acrylonitrile and dimethyl maleate do not react even with irradiation.
Acidic Nature of Chemisorption Sites on Silica-Alumina and Alumina Catalysts. Characterization by UV Spectra of Adsorbed p-Mtroaniline
Authors: Mizuno Koichi , Take Jun-ichiro , Yoneda Yukio
Published: July 2006

Chemisorbed p-nitroaniline (PNA) gives two bands at 245 and 445 nm on silica-alumina and one band at 450 nm on alumina. The present paper deals with the nature of these chemisobed species and of the chemisorption sites. Kinetic studies of PNA chemisorption onto silica-alumina from cyclohexane solution revealed that the chemisorbed species responsible for the 245 nm band was formed with an activation energy by 0.9 kcal/mol smaller than that responsible for the 445 nm band. The two bands on silica-alumina are due conclusively to two different chemisorbed species. Comparison among UV absorption spectra of PNA in various solutions and on various solid surfaces led to the conclusion that the 245 nm band is ascribable to PNA chemisorbed on Bronsted acid sites and the 445 and 450 nm bands to PNA chemisorbed on Lewis acid sites (i.e. surface Al3+ ions).
The Michael Reaction of Silyl Enol Ethers with α,β-Unsaturated Eetones and Acetals in the Presence of Titanium Tetraalkoxide and Titanium Tetrachloride
Authors: Narasaka Koichi , Soai Kenso , Aikawa Yukiko , Mukaiyama Teruaki
Published: July 2006

Silyl enol ethers react with α,β-unsaturated ketones and esters in the presence of TiCl4 or in the coexistence of TiCl4 and Ti(Oi-Pr)4 to give 1,5-dicarbonyl compounds in good yields. The reactions of acetals derived from α,β-unsaturated ketones with silyl enol ethers in the coexistence of TiCl4 and Ti(Oi-Pr)4, followed by successive addition of 1,2-ethanedithiol, give the Michael products, δ-keto ethylene thioacetal, in good yields. The reaction of silyl enol ethers with acetals derived from α,β-unsaturated aldehydes also gives the Michael products when Ti(OCEt3)4 is employed instead of Ti(Oi-Pr)4 in the above experiment and is successfully applied to the simple synthesis of dihydro rose oxide.
A Spectrophotometric Study of Copper(I) Chloro-Complexes in Aqueous 5M Na(Cl, ClO4) Solutions
Authors: Sugasaka Kazuhiko , Fujii Ayako
Published: July 2006

The complex formation of copper(I) ions in aqueous 5 M Na(Cl, ClO4) solutions was studied by spectrophotometry covering a pH range from acidic to alkaline. Over the range of the chloride concentration of 0.05–5 M in acidic solutions, the complexes CuCl2− and CuCl32− were found. The molar extinction coefficients of the complexes were determined at various wavelengths from 220 to 320 nm. The equilibrium constant for the reaction CuCl2−+Cl−=CuCl32− was determined to be 1.95. Chloro-hydroxo mixed complexes of copper(I), such as CuClOH−, CuCl2OH2−, and CuCl(OH)22− were formed in alkaline solutions and the molar extinction coefficients of these species were estimated. The formation constants βpq=[CuCl2+p(OH)q]/[CuCl2][Cl]p[OH]q of the complexes were evaluated to be as follows: β−11=(1.1±0.1)×104,β01=(4.1±0.3)×103, and β−12=(3.8±0.7)×106. No polynuclear complex was formed in the solutions.
Studies of Unusual Amino Acids and Their Peptides. VII. The Syntheses and the Reactions of Iminopeptides
Authors: Yamada Takashi , Suegane Kazuko , Kuwata Shigeru , Watanabe Hiroshi
Published: July 2006

As a basic study for synthesis of bottromycin, the syntheses and the reactions of iminodipeptides were investigated. Nine N-benzyloxycarbonyl(Z) iminodipeptides were prepared by the condensation of ethyl Z-amino carboximidates with amino acids according to the method of Ried et al. All the imidates were prepared from the corresponding nitriles, and ethyl N-Z-2-pyrrolidinecarboximidate (IIIf) was also successfully obtained from Z-proline thioamide by the method of Suydam et al. Though Z-(iminoprolyl)glycine was easily deprotected or esterified, its C-terminal could not be elongated because it was likely to cyclize into an imidazolone ring. This side reaction could be avoided by locating a carboxyl group further apart from an imino group in a molecule; i. e., the imidate (IIIf) could be coupled with methyl glycylphenylalaninate, thus affording the desired iminotripeptide, Z–ImPro–Gly–Phe–OMe, in a good yield.
A New Synthesis of Pyrocin and Related Compounds
Authors: Takeda Akira , Sakai Takashi , Shinohara Shohei , Tsuboi Sadao
Published: July 2006

A new synthesis of pyrocin (1) and related compounds is described. The reaction of 2-benzoyl-4,4-dimethyl-2-buten-4-olide (5b) with 2-methyl-1-propenylmagnesium bromide (6) in the presence of CuCl gave α-benzoylpyrocin (7b) in 90% yield. The product of 7b with a specific rotation of +2.43° was obtained when the reaction was carried out in the presence of (−)-sparteine. α-Acetylpyrocin (7a) was prepared in the similar manner in 63% yield. The treatment of 7a and that of 7b with ethanolic sodium ethoxide gave 1 in 65% and 81% yields, respectively. The reaction of 1 with large excess of SOCl2 in absolute ethanol gave ethyl 3-(1-chloro-1-methylethyl)-5-methyl-4-hexenoate (8) in 82% yield. Similar treatment of 7 with SOCl2 gave ethyl 2-substituted-4-(2-methyl-1-propenyl)-5,5-dimethyl-4,5-dihydrofuran-3-carboxylate (12). Compound 8 was transformed to ethyl trans-(±)-chrysanthemate (2) in 75% yield.
Substituent Effects on the Photo-ethoxycarbonylation of Monosubstituted Ferrocenes
Authors: Akiyama Takeo , Kitamura Taro , Kato Takao , Watanabe Haruo , Serizawa Toshio , Sugimori Akira
Published: July 2006

The effect of the substituent in the ferrocene nucleus on the photo-ethoxycarbonylation of monosubstituted ferrocene in carbon tetrachloride–ethanol solution is described. The electron withdrawing substituents, such as chloro, bromo, iodo, cyano, and acetyl, retarded the photo-ethyoxycarbonylation, whereas the electron releasing substituents, such as ethyl accelerated the reaction. The electronic effects which affect the formation of the charge transfer complex and those which affect the reactivity of the cyclopentadienyl ring toward the attack of a trichloromethyl radical can be considered for the photo-ethoxycarbonylation.
ESR Studies of Nitrogen-centered Free Radicals, N-Aryl-N-phenylthioaminyls
Authors: Miura Yozo , Kinoshita Masayoshi
Published: July 2006

A variety of substituted N-phenyl-N-phenylthioaminyls (2), Ar–\dotN–S–Ar′, were generated by the photolysis of benzenesulfenanilides (1) in benzene in the presence of di-t-butyl peroxide or by the oxidation of 1 in benzene with lead dioxide. The ESR spectra of the radicals were completely analyzed by labeling some radicals with deuterium and with the aid of a computer simulation technique. The unpaired electron is distributed mainly on the nitrogen atom and the N-phenyl ring. The values of an were plotted against the σ or σ− in the Hammett equation, and it was found that 2, in terms of Walter’s criteria, belong to class S.
Intramolecular Cyclization of 3,4-Epoxy Alcohols; Oxetane Formation
Authors: Murai Akio , Ono Mitsunori , Masamune Tadashi
Published: July 2006

1-(2,3-Epoxypropyl)-1-cyclohexanol (1) and its methyl analogues (2 and 3), when treated with base in 75% aqueous dimethyl sulfoxide, gave the corresponding oxetanes (9–11) as the main products, while treatment of compound 1 under anhydrous conditions afforded the oxolane dimer (17) as the sole identified product.
Production of 61Cu by α and 3He Bombardment on Cobalt Target
Authors: Homma Yoshio , Murakami Yukio
Published: July 2006

In order to determine the optimum irradiation conditions to produce the 61Cu for nuclear medical use, excitation curves and thick-target yield curves were determined for the α reactions producing 61Cu, 57Co, and 58Co, and 3He reactions producing 61Cu, 56Co, 57Co, and 58Co, both from natural cobalt. The 59Co(α, 2n) 61Cu and the 59Co(3He, n) 61Cu reactions give cross section peaks of 340 mb and 6 mb at 25 MeV and 35 MeV, respectively. The 61Cu thick-target yields for these reactions at 40 MeV were 6 mCi/μAh and 110 μCi/μAh, respectively. A simple and reliable anion-exchange method was developed to provide carrier-free 61Cu. The purity of 61Cu was determined with a Ce(Li) spectrometer. Photopeak efficiencies have been calculated at principal γ-ray energies of 61Cu, 64Cu, and 67Cu, for a 1/2 in. NaI scintillation camera. Alternative nuclear reactions and the methods for producing 61Cu are compared.
Binuclear Metal Complexes. XVI. Hetero Metal Binuclear Complexes with N,N′-Bis(3-carboxysalicylidene)ethylenediamine
Authors: Okawa Hisashi , Nishida Yuzo , Tanaka Mitsunori , Kida Sigeo
Published: July 2006

Hetero metal binuclear complexes, MM′ (fsaen)·nH2O (M=Cu(II) and Ni(II); M′=Cu(II), Ni(II), Co(II), Fe(II), and Mn(II); n=1–3), with N,N′-bis(3-carboxysalicylidene)ethylenediamine (H4fsaen) have been synthesized and characterized, where M and M′ denote the metal ion coordinated by the N2O2-coordinating atoms and the O4-coordinating atoms, respectively. The magnetism of CuNi(fsean)·3H2O and CuCo(fsaen)·3H2O is explained in terms of the Heisenberg model. The magnetism of NiCu(fsaen)·H2O, NiCo(fsaen)·2H2O, and NiMn(fsaen)·2H2O obeys the Curie-Weiss law, demonstrating the binuclear structure to be composed of one diamagnetic nickel(II) and one paramagnetic M′(II) ions. CuFe(fsaen)·2H2O, NiFe(fsaen)·2H2O, and CuMn(fsaen)·H2O each shows unusual magnetic property.
A Shock Tube Study of the Decomposition Mechanism of Chloroform in the Presence of Deuterium or Methane
Authors: Yano Takayuki
Published: July 2006

Chloroform was pyrolyzed in the absence and in the presence of one of three additives—D2, CH4, and CD4, over the temperature range of 1000–1200 K in a single-pulse shock tube. The main products of the decomposition of chloroform by itself were tetrachloroethylene and hydrogen chloride. On the other hand, tetrachloroethylene, trichloroethylene, dichloromethane, and hydrogen chloride were the major products in the presence of D2, while in the chloroform–methane systems they were tetrachloroethylene, trichloroethylene, 1,1-dichloroethylene, vinyl chloride, ethane, and hydrogen chloride. From the deuterium distribution of the products, as determined by mass spectrometry, it is found that the hydrogen atoms of trichloroethylene and 1,1-dichloroethylene mainly came from chloroform and methane respectively, while the hydrogen atoms of vinyl chloride came from both chloroform and methane. The change in the product distribution resulting from the addition of deuterium or methane and the hydrogen isotopic distribution suggest that the mechanism is composed of Cl atom elimination in the initiation step and successive reactions involving “hot” molecule reactions. The hydrogen isotopic distribution of vinyl chloride may indicate that the three-centered hydrogen elimination (αα) process competes with the four-centered (αβ) process in the decomposition of “hot” 1,1-dichloroethane.
Activity Coefficients of Glycylglycine and α-Aminobutyric Acid in Aqueous Sucrose Solutions
Authors: Uedaira Hatsuho
Published: July 2006

The activity coefficients of glycylglycine and α-aminobutyric acid in aqueous sucrose solutions have been measured by the isopiestic vapor pressure method at 25 °C. α-Aminobutyric acid is salted-out by sucrose, the effect increasing with an increase in the concentration of sucrose and a decrease in the concentration of amino acid. However, in the glycylglycine–sucrose–water system at lower concentrations of solutes salting-in of glycylglycine by sucrose takes place and then salting-out predominates at concentrations higher than 1 mol kg−1 glycylglycine and 2 mol kg−1 sucrose. The pairwise interactions and the free energy of the transfer of amino acids from water to various concentractions of sucrose solutions are calculated. The results account for the stabilizing effect of sucrose on the higher structure of globular proteins.
Luminescence of Aminopyridines and Related Molecules
Authors: Kimura Ko , Takaoka Hideko , Nagai Ryo
Published: July 2006

Quantum yields and lifetimes of fluorescence and phosphorescence were measured for 2-, 3-, 4-aminopyridines, 2-, and 4-(dimethylamino)pyridines in ethanol–methanol, in an acidic ethanol–methanol mixture, and in a mixture of triethylamine and 2-methyltetrahydrofuran at 300 K and at 77 K. Quantum yields of fluorescence of 2- and 3-substituted pyridines are appreciable, while those of 4-substituted pyridines are as low as or less than 0.01 at 77 K. In view of the significant quantum yields of fluorescence for 2- and 3-substituted pyridines in the aprotic solvent, it may be concluded that the higher excited 1(nπ*) or 3(nπ*) states are not so close in energy to the lowest excited 1(ππ*) states.
The Effect of Crown Ethers on the Reaction of Alkali Metal Trichloroacetate with Cyclohexene under Decarboxylative Conditions
Authors: Idemori Kenjiro , Takagi Makoto , Matsuda Tsutomu
Published: July 2006

The reaction between alkali metal trichloroacetate and cyclohexene was studied in an aprotic medium in the presence and also in the absence of crown ethers. The crown ethers catalyzed decarboxylation but reduced the yield of the dichlorocarbene adduct.
The Preparation of 3,5-Diacetoxy-1-cyclopentene
Authors: Kurozumi Seizi , Toru Takeshi , Tanaka Toshio , Miura Shuji , Kobayashi Makiko , Ishimoto Sachio
Published: July 2006

The phase-transfer reaction of 3,5-dibromo-1-cyclopentene with potassium acetate was studied using trialkylamines and a trialkylphosphine as catalysts. Various metal acetates were examined for their effects in this reaction.
The Structure of the Cyclodextrin Complex. V. Crystal Structures of α-Cyclodextrin Complexes with p-Nitrophenol and p-Hydroxybenzoic Acid
Authors: Harata Kazuaki
Published: July 2006

α-Cyclodextrin (α-CDx) forms a 1 : 1 complex with p-nitrophenol (p-NP) and p-hydroxybenzoic acid (p-HB). The crystal structures were determined by the X-ray method. The crystals of both complexes are orthorhombic, and the space group is P212121 with Z=4. The cell dimensions are a=13.455(1), b=15.296(1), and c=24.740(3) Å for the p-NP complex, and a=13.356(1), b=15.342(1), and c=24.896(2) Å for the p-HB complex. The crystal structures were determined on the basis of the isomorphous structure of the p-iodophenol complex by using 4811 reflections for the p-NP complex and 4692 reflections for the p-HB complex, and refined by the block-diagonal least-squares method to the final R-values of 0.066 and 0.067 respectively. In both complexes, the guest molecule is included in the α-CDx cavity, and the α-CDx ring is deformed from the regular hexagonal symmetry as a result of the inclusion of the planar molecule. The nitrophenyl or carboxyphenyl group is located in the cavity, while the phenolic hydroxyl group protrudes from the secondary hydroxyl side of the cavity. Several intermolecular hydrogen-hydrogen contacts shorter than the ideal van der Waals contact are observed between α-CDx and guest molecules, indicating that the guest molecule is rigidly fixed in the cavity. The nitro or carboxyl group is situated on the O(6) side and is hydrogen-bonded to water or a hydroxyl group of the adjacent α-CDx molecule. The geometry of the complex gives a reasonable model for the α-CDx-substrate complex in the hydrolysis of p-nitrophenyl acetate and p-carboxyphenyl acetate catalyzed by α-CDx.
Photolysis of Ethyl Azidoformate in Ethers and in Alcohols
Authors: Torimoto Noboru , Shingaki Tadao , Nagai Toshikazu
Published: July 2006

Ethoxycarbonyl nitrene, generated by the photolysis of ethyl azidoformate (I), was inserted preferentially into the α C–H bonds of acyclic ethers. Each of the reactions with acyclic ethers gave N-alkoxyurethane via a cleavage of the C–O bond, indicating that an O–N ylide is an intermediate of the nitrene reaction. Comparing sensitized photolysis with direct photolysis of I in ethers and in alcohols, it was found that the nitrene insertion into the α C–H bonds of ethers proceeds for both singlet and triplet and that the insertion into the β and γ C–H bonds of ethers and the O–H bonds of alcohols proceeds only for the singlet.
Formose Reactions. III. Evaluation of Various Factors Affecting the Formose Reaction
Authors: Shigemasa Yoshihiro , Fujitani Takashi , Sakazawa Chikahiro , Matsuura Teruo
Published: July 2006

By an analytical method using oxidation-reduction potential measurements of the formose reaction, which were previously shown to be useful for separately analyzing the induction and the formose-forming steps, the influence of various factors on each step and on the sugar yield were examined. It was found for the batchsystem formose reaction that the rate of both steps and the sugar yield are affected by the concentration of formaldehyde, the amount of calcium hydroxide, and also by the ratio of the two. The dissolved calcium ion is believed to be an essential catalyst for either the induction or the formose-forming step, with the hydroxy anion playing significant role as the catalyst for the latter step. The optimum conditions necessary for obtaining the sugars in high yields are discussed.
Asymmetric Reactions. II. Asymmetric Synthesis of Methyl α-Phenylpropionate by Means of Chiral Polymers
Authors: Yamashita Tetsushi , Yasueda Hiroshi , Miyauchi Yasushi , Nakamura Nobuo
Published: July 2006

The asymmetric addition of methanol to phenylmethylketene was carried out in the presence of propionylcinchonine and poly(acryloylcinchonine). The use of poly(acryloylcinchonine) produced additional products with higher optical yields than that of propionylcinchonine. The highest optical yield (35%) was obtained with the above polymeric catalyst at −78 °C. An insoluble, cross-linked polymer obtained by the co-polymerization of acryloylcinchonine with N,N′-diacryloylhexamethylenediamine, was also used as a catalyst. The products obtained for the cross-linked polymer showed a linear correlation between logkR/ks and 1/T while those with non-cross-linked poly(acryloylcinchonine) exhibited a relationship deviating somewhat from linearity. A linear relationship was also observed using insoluble, cross-linked poly(acryloylquinine).
Reduction by a Model of NAD(P)H. XIV. Mechanistic Consideration on the Role of Metal Ion
Authors: Ohno Atsuyoshi , Kimura Takahide , Yamamoto Hiroyuki , Kim Seung Geon , Oka Shinzaburo , Ohnishi Yutaka
Published: July 2006

The driving force for the catalytic activity of metal ions on the reduction of α-keto esters with an NAD(P)H-model compound has been discussed. The scope of the reaction and spectroscopic investigations as well as molecular orbital consideration have revealed that the transition state of the reaction consists of a ternary complex in analogy with a coenzyme–enzye–substrate complex in an enzymic system. It is concluded that, at the transition state, one electron migrates from a model compound to a substrate through a metal ion, which is followed by the transfer of a proton.
The Highly Selective Sulfonylation of Cycloheptaamylose and Syntheses of Its Pure Amino Derivatives
Authors: Tsujihara Kenji , Kurita Hironori , Kawazu Mitsutaka
Published: July 2006

Mesitylenesulfonyl chloride reacted selectively with primary hydroxyl groups of cycloheptaamylose to give hexakis (6-O-mesitylsulfonyl)cycloheptaamylose (II) and heptakis(mesitylsulfonyl)cycloheptaamylose (I). The selectivity of mesitylenesulfonyl chloride in the preferential sulfonylation is 24 times larger than that of tosyl chloride. Pure hexakis(6-azido-6-deoxy)cycloheptaamylose (III) and hexakis(6-amino-6-deoxy)cycloheptaamylose (IV) were synthesized from II. Pure heptakis(6-amino-6-deoxy)cycloheptaamylose (VII) and mixture of positional isomers of hexakis(6-amino-6-deoxy)mesitylsulfonylcycloheptaamylose (VIII)* were obtained by the catalytic hydrogenation of the corresponding azido compounds V and VI,* which were themselves given by the reaction of I with sodium azide. These amino derivatives, IV, VII, and VIII,* showed significant antimicrobial activities against such gram-negative bacteria as Escherichia, Shigella, and Pseudomonas. These compounds also exhibited hypocholesterolemic effects in the chick when added in the diet for two weeks, probably through sequestration of intestinal bile acids.
A Convenient Synthesis of (±)-Taxodione, (±)-Ferruginol, and (±)-Sugiol
Authors: Matsumoto Takashi , Usui Shuji , Morimoto Toshitaka
Published: July 2006

The condensation of β-cyclocitral (4); with 3-isopropyl-4-methoxybenzyl chloride (5) in the presence of lithium naphthalenide gave an alcohol (6), which was then oxidized to the corresponding α,β-unsaturated ketone (7). The Intramolecular cyclization of 7 with polyphosphoric acid yielded (±)-12-methoxyabieta-8,11,13-trien-6-one (8) and its cis-isomer (9), which was then successfully converted into 8  via an enol acetate (11). The 8 ketone was dem ethylated with boron tribromide to give a phenol (18), and this was then reduced with lithium aluminium hydride to yield the corresponding alcohol (19). The oxidation of the C-11 position in 19 with benzoyl peroxide gave (±)-12-benzoyloxyabieta-8,11,13-trien-6β,11-diol (20), which, on reduction with lithium aluminium hydride and subsequent oxidation with Jones reagent, afforded (±)-taxodione (1). The reductive cleavage of the hydroxyl group in 6 with dichloroaluminium hydride, followed by cyclization, gave (±)-ferruginyl methyl ether (12), which was then demethylated with boron tribromide to produce (±)-ferruginol (2). Further, the oxidation of 12 with chromium trioxide, followed by demethylation, gave (±)-sugiol (3).
X-Ray Diffraction Studies of the Metal Soaps of Fatty Acids of Odd Carbon Numbers
Authors: Ogino Keizo , Saito Toshio
Published: July 2006

X-Ray diffraction patterns have been observed for metal soaps of fatty acids with odd carbon numbers. The soaps of Pb, Cd, Ba, and Zn were prepared from the fatty acids of hexanoic, heptanoic, nonanoic, decanoic, undecanoic, dodecanoic, tridecanoic, tetradecanoic, pentadecanoic, hexadecanoic, heptadecanoic, and octadecanoic, the long spacings of which were studied in comparison with those of sodium soaps. The most prominent characteristic of these soaps is the presence of a definite order of long spacing which is directly proportional to the number of carbon atoms in the hydrocarbon chains, this is in contrast to the sodium soaps, which show a zigzag relation.
Self-Consistent Renormalized RPA: The Electronic Excited States of Benzene in the INDO/S Method
Authors: Ito Hirotoshi , I’Haya Yasumasa J
Published: July 2006

A self-consistent renormalized RPA and its approximated analogues are compared in the calculation of the electronic excited states of benzene by using the INDO/S method.
The Detection of Hg(63P1 and 63P0) Atoms by an Atomic Absorption Method and Their Quenching Cross Sections
Authors: Horiguchi Hiroyuki , Tsuchiya Soji
Published: July 2006

The absorption intensities of the 435.8- and 404.7-nm lines by Hg(63P1 and 63P0) atoms were calculated taking into account the hyperfine structure under the assumption of a Doppler spectral line shape. The calculated values were tested by comparison with experimental absorption of the line in an Ar+N2+Hg mixture illuminated by 253.7-nm radiation. This procedure led to the conclusion that the ratio of the spectral half-width of the 404.7-nm line from a low-pressure Hg lamp to that of the Hg(63P0) absorption line should be 2.25±0.25 instead of the value of 5 determined in the previous experiment. On the basis of this value, the quenching cross sections of the excited Hg atoms reported in the previous paper were revised. The corrections are generally less than 20%, so that it is not necessary to change the previous conclusions.
Electronic Interactions in Triple Exciplex of the 1,4-Dicyanobenzene and Naphthalene System
Authors: Mimura Tsutomu , Itoh Michiya , Ohta Toshiaki , Okamoto Toshihiko
Published: July 2006

Semiempirical SCF-MO-CI caluculation was carried out for the 1,4-dicyanobenzene (DCB) and naphthalene system which is known to form exciplex (DA)* and triple exciplex (D2A)*. Potential energy curves of the electronic interactions between excimer and electron acceptor molecule, and between exciplex and electron donor molecule were constructed. The results show that the array of component molecules in the triple exciplex is DDA, and the stabilization energy of triple exciplex is ≈0.4 eV from the excimer and ≈0.2 eV from the exciplex. They are in line with results reported on the experiment of exciplex and triple exciplex formation.