bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal Square Planar-to-octahedral Transformation of Nickel(II) Complexes Containing 1,2-Diphenyl-1,2-ethanediamine in the Solid Phase
Authors: Ihara Yoshinori , Tsuchiya Ryokichi
Published: July 2006

The following ten nickel(II) complexes with meso- or dl-1,2-diphenyl-1,2-ethanediamine (abbreviated as meso-stien and dl-stien, respectively) were prepared, and their thermal behavior was investigated in the solid phase: [Ni(meso-stien)2]X2 (X=Cl, Br, I, NO3, or ClO4), [Ni(dl-stien)2]X2 (X=I or ClO4), and [Ni(H2O)2(dl-stien)2]X2 (X=Cl, Br, or NO3). The square planar bis(dl-stien) complex chloride, bromide, and nitrate obtained by thermal dehydration of their respective octahedral diaqua complexes were found by various techniques to be transformed, upon further heating, to the octahedral diacido bis(dl-stien) complexes. The complexes containing dl-stien have a stronger tendency to show such structural transformations than those containing meso-stien. The reason for this difference is discussed.
The Thermal Properties of (4-Substituted Cyclohexyl) 4-Substituted Cinnamates
Authors: Hayashi Shigetsugu , Takenaka Shunsuke , Kusabayashi Shigekazu
Published: July 2006

The thermal properties for a homologous series of 4-alkylcyclohexyl 4-alkoxy- and 4-cyanocinnamates are examined. They exhibit nematic phases with low melting points. The effect of the cyclohexyl group on the mesophase stability is discussed.
Syntheses and Chelating Properties of Sulfonamidoquinolines
Authors: Nakamura Hiroshi , Yoshida Tsukasa , Todoko Masaaki , Ueno Keihei , Takagi Makoto
Published: July 2006

Seven chelating agents were synthesized. The complexation properties of these reagents with divalent metals (Cu2+, Co2+, Ni2+, Zn2+) were investigated in dioxane–water (75% dioxane, 25% water), and the complex formation constants were compared with those of 8-quinolinol as a reference chelating agent. These sulfonamidoquinoline reagents formed ML and ML2 type complexes, and the order of complex stabilities followed Irving-Williams’ order except for 2-methyl substituted derivatives. With 2-methyl derivatives, Ni2+ complexes were less stable than Co2+ complexes. Structural characteristics of sulfonamides as chelating agent were discussed in detail.
The Volume Profile for the Aquation Reactions of trans-[CoBr(NO2)(en)2]+ and trans-[CoCl(N3)(en)2]+
Authors: Kitamura Yoichi , Nariyuki Shinji , Kondo Toshiaki
Published: July 2006

For the aquation of trans-[CoBr(NO2)(en)2]+, the activation volume at atmospheric pressure (ΔV\eweq) is 0.3±0.2 cm3 mol−1 at 10 °C, and the reaction volume (ΔV) is −10.4±0.1 cm3 mol−1 at 7.4 °C, both in pure water. For trans-[CoCl(N3)(en)2]+, ΔV\eweq is 0.7±0.6 cm3 mol−1 at 30 °C in 0.011 M HClO4 (1 M=1 mol dm−3) and ΔV is −11.0±0.6 and −11.4±0.3 cm3 mol−1 at 25 °C in 0.008 M HClO4, thus yielding the trans and the cis aqua products respectively.
Fragmentation of Human Erythrocyte Ghosts and Their Application as a Carrier of Heme Complex
Authors: Seki Noriko , Ohno Hiroyuki , Tsuchida Eishun , Sasakawa Shigeru
Published: July 2006

Human erythrocyte ghosts were taken into fragments by sonication. The average radius of the fragmented ghosts gradually decreased with the sonication time. The fragmented ghosts were obtained as spheres and reached to about 0.1 μm. In spite of the change in radius, their membrane fluidity was the same as that of the unsonicated ghost membrane. The [meso-α,α,α,α-tetrakis(o-pivalamidophenyl)porphinato]iron(III)-mono (1-dodecyl-2-methylimidazole) complex was incorporated into the hydrophobic region of the fragmented ghost membrane. This hybrid showed a semistable oxygen adduct in pH 7.0 phosphate buffer solution.
The Platinum Catalyzed Reduction of Nitroarenes to Aminoarenes with Carbon Monoxide and Water
Authors: Watanabe Yoshihisa , Tsuji Yasushi , Ohsumi Tatsuya , Takeuchi Ryo
Published: July 2006

Nitroarenes were transformed into the corresponding aminoarenes in high yields at 80 °C with carbon monoxide (an initial pressure 30–60 kg cm−2) and water in the presence of a catalytic amount of a platinum catalyst. The platinum catalyst was combined with tin(IV) chloride, triphenylphosphine and triethylarnine. This combination was essential for the high catalytic activity.
Cobalt(III) Complexes with Quadridentate Ligands. V. The Preparation and Properties of Paramagnetic and Diamagnetic cis-β2-Isomer of the 5-Nitrosalicylato(quadridentate amine)cobalt(III) Complexes
Authors: Yamamoto Yoshihisa , Kudo Hiroko
Published: July 2006

Several green paramagnetic 5-nitrosalicylato(quadridentate amine)cobalt(III) chloride nitrate hydrates, [Co(5-NO2sal)L]Cl·NO3·nH2O (L: 2,3,2-tet, 3,2,3-tet, and 3,3,3-tet) and the corresponding orange diamagnetic nitrate hydrates, [Co(5-NO2sal)L]NO3·nH2O, have been isolated and characterized by analytical, spectroscopic, and magnetic methods.
Determination of a Small Amount of a Biological Constituent by the Use of Chemiluminescence. II. Determination of Albumin as a Model Protein by Means of the Flow-injection Analysis Using a Cobalt(III) Complex Compound as a Catalyst
Authors: Hara Tadashi , Toriyama Motohiro , Tsukagoshi Kazuhiko
Published: July 2006

A new procedure for the determination of 8×10−9–3×10−7 mol dm−3 bovine serum albumin as a model protein has been established on the basis of the fact that the catalytic activity of cis-tetraamminediaquacobalt(III) sulfate for the chemiluminescent reaction between luminol and hydrogen peroxide decreases in the presence of bovine serum albumin.
Structure and Synthesis of Miyaginin, a p-Allylphenyl Glycoside from Lespedeza thunbergii forma macrantha
Authors: Ojika Makoto , Kuyama Hiroki , Niwa Haruki , Yamada Kiyoyuki
Published: July 2006

The structure of miyaginin previously reported as p-vinylphenyl O-d-xylosyl-(1→6)-d-glucoside without stereochemical assignment of two glycosidic linkages was reinvestigated by spectral and chemical means and shown to be revised as p-allylphenyl O-β-d-xylopyranosyl-(1→6)-β-d-glucopyranoside (p-allylphenyl β-primeveroside). In order to confirm the revised structure, an unambiguous synthesis of miyaginin was performed.
Vacuum Sublimation Behavior of Metal Complexes of Thio-β-diketones. Purification of Manganese(II), Iron(III), Cobalt(III), Nickel(II), Copper(II), Zinc(II), Palladium(II), Silver(I), and Cadmium(II) with 1,1,1-Trifluoro-4-(2-thienyl)-4-mercapto-3-buten-2-one
Authors: Honjo Takaharu , Shima Shigeki
Published: July 2006

A vacuum sublimation apparatus with a continuous temperature gradient (25–260 °C) along the tube (0–50 cm) at 2×10−2 Torr (1 Torr≈133.322 Pa) was used. STTA (1,1,1-trifluoro-4-(2-thienyl)-4-mercapto-3-buten-2-one) and its metal chelates of MnII, FeIII, CoIII, NiII, CuII, ZnII, and PdII sublimed quantitatively without thermal decomposition, while the chelates of AgI and CdII were accompanied by thermal decomposition.
Photoelectrochemical Behavior of the Fe(CN)52− Complexes Coordinated to the Poly(4-vinylpyridine) Film on Graphite Surfaces
Authors: Oyama Noboru , Yamamoto Hisao , Ohsaka Takeo , Kaneko Masao
Published: July 2006

Photoelectrochemical reaction of the Fe(CN)52− complex (PVP[Fe(CN)52−]n) coordinated to the unprotonated poly(4-vinylpyridine) (PVP) film on a graphite electrode was examined in an aqueous solution. It was found that the carbon electrode coated with the PVP[Fe(CN)52−]n generates the long-time responses of the photocurrents under irradiation of visible light and that the mechanism of its photochemical reaction is different from that for the photochemical reaction of [Fe(CN)6]3− in a bulk solution, where the dissociation reaction of [Fe(CN)6]3− to its aqua ion occurs.
Synthesis of Fluorescent Peptides and Their Phosphorylation by the Catalytic Subunit of cyclicAMP-dependent Protein Kinase
Authors: Kondo Hiroki , Takaki Katsunori , Kuroki Ryoichi , Tada Akihiro , Fukumoto Kunihiro , Sunamoto Junzo
Published: July 2006

The following two fluorescent peptides were prepared as substrates of the cyclic AMP-dependent protein kinase reaction: Leu–Arg–Arg–Ala–Ser–Leu–X; 1 (X= 2-(dansylamino)ethylamino or DAE) and 2 (X=4-methyl-2-oxo-7-chromenylamino or MCA). Both peptides were phosphorylated by ATP and the catalytic subunit of cyclidAMP-dependent protein kinase from bovine heart in a stoichiometric manner. Phosphorylation of peptide 1 is accompanied by a 10% increase in the fluorescence intensity at 550 nm. This enables one to assay peptide phosphorylation by fluorescence spectroscopy. The kinetic parameters obtained by this and the conventional phosphocellulose paper method for this phosphorylation were the following: Km 7.8 μM and Vmax 35 μmol·min−1·mg−1 for 1, and Km 7.4μM and Vmax 16 μmol·min−1·mg−1 for 2.
Reaction of Trifluoronitrosomethane with Arenesulfonohydrazides. Synthesis of N-Trifluoromethyl-N-hydroxyarenesulfonamides
Authors: Sekiya Akira , Umemoto Teruo
Published: July 2006

The reaction of trifluoronitrosomethane 1 with arenesulfonohydrazides resulted in the formation of N-trifluoromethyl-N-hydroxyarenesulfonamides 3 which were characterized by spectral and elemental analyses. It showed a sharp contrast to the reaction of 1 with acyl- or carbamoylhydrazines, which afforded the corresponding trifluoromethylazo compounds. As an alternative route, 3 could be synthesized by the reaction of 1 with arenesulfinic acids or their salts. The sulfonamides 3 were converted to the corresponding methyl ethers or tosylates.
A Molecular Orbital Study of the 1,2-Migration Reaction of Substituted Cyclohexadienyl Radicals
Authors: Kikuchi Osamu , Shimomura Satoshi
Published: July 2006

The 1,2-migration reaction of cyclohexadienyl radicals was examined on the basis of an open-shell restricted self-consistent field (SCF) MINDO/3 calculation. For the NO2- and OH-substituted cyclohexadienyl radicals, the 6-substituted isomers (1; X=H, Y=NO2 or OH) were calculated to be the least stable and apt to undergo a 1,2-hydrogen shift. The electron-withdrawing groups were predicted to have high migratory aptitude.
A Study of Inorganic Ion Exchangers. IX. The Synthesis of AlxZrH2−3x(PO4)2·yH2O and Its Characteristics
Authors: Kobayashi Etsuro
Published: July 2006

To make a material with specific functions such as those of a catalyst, a layer-structure compound with the formula of AlxZrH2−3x(PO4)2·yH2O (x≤2⁄3) was synthesized by a hydrothermal reaction between ZrOCl2·8H2O and Al(H2PO4)3 at 200–270°C. The product had a layer spacing of 7.75 Å, slightly longer than α-Zr(HPO4)2·H2O (7.62 Å), and fairly good thermal stability at 250–500°C. However, the above objective was not attained by ion-exchange between various zirconium phosphates and an aqueous solution of aluminium chloride.
Thermal Decomposition of Cobalt(II) Halide Complexes of Tetramethylurea and Related Cyclic Ureas
Authors: Sone Kozo , Kikuchi Masae , Ogasawara Kaede , Kuya Miuaco Kawashita , Pereira Anamaria Dias
Published: July 2006

TG-DTA studies revealed that the complexes CoX2L2 (L=tmu, dmeu or dmpu (see text); X=Cl, Br or I) decompose into CoX2 and 2L by slight heating. The ease of this decomposition decreases in the orders of tmu>dmeu>dmpu and Cl>Br>I, corresponding to the orders of coordination abilities of these ligands.
A Solubility Phase Diagram Study on Optical Resolution of Bis(ethylenediamine)oxalatocobalt(III) (1+) by l-α-Amino Dicarboxylate(1−)
Authors: Yamanari Kazuaki , Igaki Michihito , Shimura Yoichi
Published: July 2006

The binary and ternary solubility phase diagrams for the system of Δ- and Λ-[Co(ox)(en)2]X (X=l-glutamate (l-Hglu−) and l-aspartate (l-Hasp−)) were determined in water. It was found that the former anion l-Hglu− behaves as an excellent resolving agent for [Co(ox)(en)2]+ but the latter anion l-Hasp− forms a pseudoracemate rac-[Co(ox)(en)2](l-Hasp).
The Platinum Complex-catalyzed Reductive N-Carbonylation of Dinitroarenes to the Biscarbamates
Authors: Watanabe Yoshihisa , Tsuji Yasushi , Takeuchi Ryo
Published: July 2006

Dichlorobis(triphenylphosphine) platinum(II) shows good catalytic activity for the reductive N-carbonylation of dinitroarenes in ethanol in the presence of a Lewis acid and triethylamine. From 2,4-dinitrotoluene, diethyl 4-methyl-1,3-phenylenebiscarbamate is obtained in 50% yield at 190°C under carbon monoxide pressure of 60 kg cm−2.
Studies on Pyrazines. II. A Novel Formation of 2-Aminopyrazine from the Reaction of Pyrazine 1-Oxide with Phosphoryl Chloride
Authors: Sato Nobuhiro , Kobayashi Michio
Published: July 2006

The reaction of pyrazine 1-oxide with phosphoryl chloride gave a 49% yield of 2-chloropyrazine and a small amount of 2-aminopyrazine. The precursor of aminopyrazine was elucidated to be a 1-(2-pyrazinyl)pyrazinium salt. The orientation of substitution in the formation of the salt was determined by reaction of deuterium labelled pyrazine N-oxides with phosphoryl chloride.
N-Allylation of Imides Catalyzed by Palladium(0)
Authors: Inoue Yoshio , Taguchi Masaaki , Toyofuku Masanori , Hashimoto Harukichi
Published: July 2006

Palladium(0)–triphenylphosphine complexes catalyzed the allylic exchange reaction of allylic esters, phenyl ethers, and isoureas with imides such as phthalimide to give N-allylic products. Among them, O-allylic isoureas were most effective in exchanging the allylic group of more complex structure. N-Allylic derivatives were also obtained by the telomerization of butadiene or allene with phthalimide catalyzed by a palladium(0) species.
Effect of Hydrogenation on Solubility of Carbonized Pitch
Authors: Yamada Yoshio , Shiraishi Minoru , Furuta Takeshi , Yamakawa Toshio , Sanada Yuzo
Published: July 2006

The effect of hydrogenation of carbonized pitch on its solubility in quinoline was investigated in connection with structural changes of the pitch during carbonization. Naphtha-tar pitch (NTP) and acenaphthylene were carbonized at 673 and 703 K, respectively, for various periods of time. The pitches thus heat-treated were hydrogenated by BenKeser reaction and the amount of quinoline insolubles (QI) in the hydrogenated pitch was determined. An acenaphthylene pitch (ACP) heat-treated for 24 h was rendered completely soluble into quinoline by the hydrogenation, whereas a considerable amount of insolubles was left in the case of NTP treated for longer residence times than 8 h. This can be explained in terms of the difference in interaction among aromatic molecules constituting the QI components derived from NTP and ACP. ACPs doped with elemental sulfur left a significant quantity of QI after the hydrogenation. The addition of sulfur is considered to form crosslinking bonds between aromatic molecules through hydrogen abstraction by the sulfur. When QI separated from carbonized NTP was hydrogenated, the degree of conversion into quinoline solubles (QS) was low as compared with that for the whole sample of the same NTP. The presence of QS in the pitch plays a very important role for the hydrogenation.
Decomposition of Blue Orthorhombic Hydrogen Molybdenum Bronze, H0.30MoO3, by Heating in vacuo and in Helium Gas
Authors: Sotani Noriyuki , Yoshida Noritetsu , Kawamoto Yoji , Kishimoto Shozo , Hasegawa Masatomo
Published: July 2006

The decomposition process of orthorhombic hydrogen molybdenum bronze, H0.30MoO3, was studied by the temperature programmed decomposition (TPD) technique in vacuo and in helium gas. The only gas liberated during the decomposition was H2O and no other gas was detected. The TPD spectrum above 150 °C was composed of three bands (PII, PIII, and PIV). The PII band corresponded to the process from H0.30MoO3 to H0.21MoO2.95 without any structural change. The PIII band corresponded to the process from H0.21MoO2.95 to H0.06MoO2.88 with the structural change and the PIV band, to the process from H0.06MoO2.88 to MoO2.85.
Temperature Effect on Decay of Ions and Radicals in Supercooled Liquids as Studied by Pulse Radiolysis and γ-Radiolysis: 1-Propanol and Ethanol
Authors: Kato Noriyuki , Miyazaki Tetsuo , Kawai Yukihiro , Fueki Kenji
Published: July 2006

The decay-rate constants, k, of dipentyl disulfide anions or benzyl radicals in 1-propanol and ethanol were measured over a temperature range of 107–230 K by pulse- and γ-radiolysis method. The decay-rate constants were found to range over nine orders of magnitude. The decay kinetics is a composite first-order reaction. Since the decay rates of reaction intermediates observed are diffusion-controlled, the decay-rate constants represent directly the rates of molecular transport in the supercooled liquids. It was found that the temperature dependence of the decay-rate constants could be expressed by the following equation.

log\frackT=−\fracAT–Tg+B,

where T is the absolute temperature, A and B are constants. Tg is the glass transition temperature. The molecular diffusion of the ions or radicals in the supercooled liquids was completely suppressed at the glass transition temperature. The temperature dependence of the decay-rate constant was compared with that of the viscosity of the matrix. It was found that the temperature, at which the molecular diffusion is completely suppressed is much higher than the temperature at which the viscosity is infinite.
Acid Dissociation Constants of Alkyl Xanthic Acids and Formation Constants of Cadmium(II) and Zinc(II) Xanthato Complexes in 1:1 v/v H2O-DMF Medium
Authors: Hayashi Kenjiro , Sasaki Yoshiaki , Inomata Shigehiro , Yanagidani Takagimi
Published: July 2006

The overall formation constants, β3, of cadmium(II) and zinc(II) complexes with alkyl xanthates (O-alkyl dithiocarbonates) were determined by polarography in the 1:1 v/v water–N,N-dimethylformamide mixture. The values of these constants increase in the order, methyl<ethyl<propyl<butyl<2-methylpropyl<1-methylethyl xanthate. This order agrees entirely with the order of the basicity of alkyl xanthates determined by using the kinetic parameter of the acid decomposition of xanthates.
Kinetics of Ligand Exchange of Tris(β-diketonato)iron(III) with Acetylacetone, Trifluoroacetylacetone, and 2-Thenoyltrifluoroacetone in Carbon Tetrachloride
Authors: Sekine Tatsuya , Inaba Kazuho
Published: July 2006

The ligand of tris(β-diketonato)iron(III) with acetylacetone (Hacac), trifluoroacetylacetone (Htfa), or 2-thenoyltrifluoroacetone (Htta) in carbon tetrachloride was exchanged with another ligand among these. The rate was measured in order to learn about the reaction mechanism in this medium; one in which no intermediates with the solvent molecules were expected. From the dependence of the rate on the particular leaving and entering ligand and from the values of ΔH\eweq and ΔS\eweq, it was concluded that in an exchange involving [Fe(acac)3] there is always a proceeding dissociative mechanism and for [Fe(tta)3] and [Fe(tfa)3] with Hacac there is an interchange mechanism. Exchanges with a fluorinated β-diketone is thought to have a character intermediate to these two mechanisms.
Dynamic NMR as a Nondestructive Method for the Determination of Rates of Dissociation. IX. Rates of Dissociative Reactions of the Coordinated Form of [o-(Diethylaminomethyl)phenyl]halodimethyl(or diphenyl)stannanes
Authors: Oki Michinori , Ohira Manabu
Published: July 2006

The coordinated form of [o-(diethylaminomethyl)phenyl]halodimethyl(or diphenyl)stannanes was found to exhibit dynamic behaviors in their 1H NMR spectra. Examination of a series of halogen compounds by total line shape analysis of the diastereotopic methylene proton signals revealed that, at 10 °C, the rates of dissociation were 11.7, 22.9, 28.6, and 73.3 s−1 for fluoro, chloro, bromo, and iodo compounds, respectively: The results are in conformity with the expectation from the electronegativity of halogens. The relatively small differences in the activation parameters in the whole series may include contribution by solvation energies. The diphenyl compound exhibited fast exchange rates relative to the corresponding dimethyl compound. This was attributed to the steric factor rather than the pπ-dπ interaction.
Solvent-extraction Behavior of Molybdenum(VI) with 1,5-Diphenylcarbazone and the Extraction-spectrophotometric Determination of Molybdenum(VI)
Authors: Ohashi Kousaburo , Nagashima Kiichiro , Seita Rumiko , Yamamoto Katsumi
Published: July 2006

The solvent extraction of molybdenum(VI) with 1,5-diphenylcarbazone (Hdpco) into chloroform, benzene, or tributyl phosphate (tbp) was studied. The molar ratio of molybdenum(VI): 1,5-diphenylcarbazone in the complex extracted into chloroform or benzene in the range from 1.0 mol dm−3 HNO3 to pH 1.9 was found to be 1:2. The extracted complex was estimated to be MoO2(dpco)2. On the other hand, molybdenum(VI) may be extracted into tbp as a mixture of MoO2(dpco)2 and MoO2(dpco)(OH)(tbp). The extraction constants, Kex(=[MoO2(dpco)2]o/[Mo(OH)6][Hdpco]o2), were determined to be 7.9×106 and 3.8×108mol−2dm6 for chloroform and benzene respectively. A black complex formulated as MoO2(dpco)2·5H2O was formed. Molybdenum(VI) can be determined over the range from 1.50 to 19.0 μg/10 cm3 within a relative error of ±4%. The interference of diverse ions will be described.
Synthetic Photochemistry. XXVIII. A Photochemical C5-Homologation of 4-Isopropenyltoluene with Methyl 2,4-Dioxopentanoate to Isolaurene and a Formal Synthesis of Cuparene
Authors: Takeshita Hitoshi , Mori Akira , Nakamura Satoshi
Published: July 2006

Starting from the photocycloaddition of methyl 2,4-dioxopentanoate with 4-isopropenyltoluene, isolaurene was synthesized, and its further conversion to 5-cuparenone constituted the formal synthesis of cuparene. For the first time, the proto-(2+2)π cycloadduct, a β-keto cyclobutanol derivative, has been isolated from the product mixture.
Structure-taste Relationships of Aspartyl Tripeptide Esters
Authors: Ariyoshi Yasuo
Published: July 2006

A series of twenty four analogues of l-α–Asp–Gly–Gly–OMe has been synthesized in relation to structural features of sweet peptides. The rule in the structure-taste relationships of dipeptides is held in the sweet aspartyl tripeptide esters. In order for the aspartyl tripeptide esters to be sweet, the second amino acid must have a d-configuration and a small, compact alkyl group (Me, Et, or i-Pr) at R2. An l-configuration of the third amino acid is required for a potent sweet taste. It has been concluded that the small alkyl group at R2 participates in binding with the receptor through a hydrophobic interaction and increases the sweetness potency.
Asymmetric Catalytic Hydrogenations of Chiral α-Keto Amides
Authors: Harada Kaoru , Munegumi Toratane
Published: July 2006

Asymmetric catalytic hydrogenations of chiral pyruvamides were carried out using palladium on charcoal (Pd-C) as a catalyst to give lactamides with the diastereoisomeric purities (d.p.) of up to 62%. It was found that there was a linear correlation between the d.p. and the dielectric constant of the solvents used in the hydrogenations of chiral pyruvamides. The results were explained by employing the chelation model and the adsorption of the phenyl group in the substrate molecule on the catalyst. The temperature effect on the d.p. of the product was also examined. The catalytic hydrogenations of chiral benzoylformamides were also performed to give low d.p. presumably, the chelation complexes of the substrates could not take a predominant conformation with the catalyst.
Theoretical Study of Relaxation Mechanism in Magnetic Field Effects on Chemical Reactions
Authors: Hayashi Hisaharu , Nagakura Saburo
Published: July 2006

External magnetic field and magnetic isotope effects on the dynamic behavior of radical pairs in solutions have been studied theoretically, where the relaxation of their electron spins was taken into account. The decay observed with some radical pairs in micellar solutions under high magnetic fields is successfully interpreted in terms of the relaxation mechanism, and the magnetic field dependence of the relaxation rates is calculated for a model system.
The Specific Heat Capacities of d-Glucose and d-Xylose in Water-Ethanol System
Authors: Kawaizumi Fumio , Sasaki Nobuo , Ohtsuka Yasushi , Nomura Hiroyasu , Miyahara Yutaka
Published: July 2006

Using an isoperibol twin calorimeter the specific heat capacities of solutions of d-glucose and d-xylose dissolved in water–ethanol mixtures (10, 20, 30, and 50 wt% of ethanol) have been measured at temperature close to 30 °C and the apparent molar heat capacity of te solutes φCp has been calculated. Dependence of φCp upon solute concentration varied markedly with the solvent composition but the variation was similar for both solutes. The infinite dilution values of φCp°  i.e.  Cp,2∞ are higher for d-glucose than for d-xylose at any compositions of the solvent system. The Cp,2∞ decreased first noticeably with the amount of ethanol in the solvent, reaching a minimum value at approximately 20 wt% of ethanol, then it increased. Values of the parameter ΔCp,2∞=Cp,2∞–Cp,2*, where Cp,2* is the specific heat capacity of the solute in the solid state, are negative in 10, 20, and 30 wt% of ethanol, while it is positive in 50 wt%. The values of ΔCp,2∞ have been discussed in its connection with the degree of structuring of the solvents.
Potassium-ion Exchange on α-Hafnium Phosphate
Authors: Tomita Isao , Banju Masaru , Noguchi Katsumi , Nakamura Toshihiro
Published: July 2006

Forward and backward pH titration curves were measured for potassium-ion exchange on crystalline α-hafnium phosphate which had been prepared by the direct-precipitation method. Exchange in each direction proceeded in two steps, and the hysteresis was observed in the region of smaller loadings of the potassium ions. Exchange in the ternary H+–Li+–K+ system was also preliminarily investigated, the selectivity of the potassium and lithium ions was what would be expected from the results of the binary hydrogen ion-alkali metal ion systems.
Synergistic Effect of Alcohol-Benzene Mixtures for Coal Extraction
Authors: Iino Masashi , Matsuda Minoru
Published: July 2006

Coals were extracted with alcohol–benzene mixtures at room temperature. For coals of high oxygen content, Yallourn and Taiheiyo coals, the extraction yields for the mixtures were much greater than those for alcohols and benzene alone. This synergistic effect was more marked for less bulky alcohols: The order was methanol>ethanol>isopropyl alcohol>t-butyl alcohol. The degree of swelling and the apparent density of the coals in alcohols were measured. The results show that smaller alcohols may permeate into pores of the coals more extensively and cause greater swelling than larger alcohols. It is reasonable to consider that this swelling of the coals then facilitates the extraction with benzene or alcohol–benzene mixtures, which are better solvents in solubility for coal molecules than alcohols. For Shin-yubari coal having low oxygen content, no such a synergistic effect was observed, probably due to the lower degree of swelling of this coal.
Ozonization of Triphenylmethane Dyes
Authors: Matsui Masaki , Nakabayashi Hideki , Shibata Katsuyoshi , Takase Yoshimi
Published: July 2006

The reaction of Malachite Green (MG, 1a), a model compound of triphenylmethane dye, with ozone proceeded via two paths. The first path involved an ozone attack at the dimethylamino moiety to give a N-formylmethylamino derivative 4a. The second path produced 4-(dimethylamino)benzophenone (2a) and p-(dimethylamino)phenol (6). Other ozonized products, 3a and 5a were also detected. The following is a discussion of the ozonization mechanism.
Heats of Solution of Bolaform Electrolytes in Water. II. Polymethylenebis(trimethylammonium) Dibromides
Authors: Tamaki Kunio , Furuya Rie
Published: July 2006

The heats of solution of polymethylenebis(trimethylammonium) dibromides [(CH3)3N(CH2)nN-(CH3)3]Br2 (n=3–6, 8, 10, and 12) and alkyltrimethylammonium bromides CnH2n+1N(CH3)3Br (n=2–6) in water were measured at 15, 25, and 35 °C. The hydrophobic character of the polymethylene groups was compared with that of alkyl groups on the basis of the changes in the heat capacity for dissolution, which were obtained from the relation between the heats of solution and the temperature.
Deprotection of 4-Methoxybenzyloxycarbonyl Group with p-Toluenesulfonic Acid in Acetonitrile. Application to a Large-scale Preparation of 7-[d-2-Amino-2-(4-hydroxyphenyl)acetamido]cephalosporanic Acid
Authors: Yamada Hirotada , Tobiki Hisao , Tanno Norihiko , Suzuki Hiroyuki , Jimpo Kiyokazu , Ueda Shinji , Nakagome Takenari
Published: July 2006

The 4-methoxybenzyloxycarbonyl group of 7-[d-2-(4-hydroxyphenyl)-2-(4-methoxybenzyloxycarbonylamino)acetamido]cephalosporanic acid was effectively removed with p-toluenesulfonic acid in acetonitrile. The mechanism of the deprotection is discussed and the role of acetonitrile can reasonably be explained in terms of the Ritter reaction.
Synthesis of 2,4-Di(p-formyl)-α-truxillic Acid by Crystal Engineering
Authors: Nakanishi Fusae , Ishii Michiko , Nakanishi Hachiro
Published: July 2006

p-Formycinnamic acid, which usually crystallizes in either the β-form or γ-form of packing, was converted into its diethyl acetal. The introduction of such bulky groups onto a benzene ring successfully provided us with the α-form of packing, from which the desired photodimer, 2,4-di(p-formyl)-α-truxillic acid (c-2, t-4-bis(p-formylphenyl)-r-1,t-3-cyclobutanedicarboxylic acid) was obtained with a yield of 85–90%.
Reactions of Azoxybenzene with Dichlorocarbene in the Phase-transfer-catalyzed System
Authors: Sekiguchi Shizen , Fujiu Tomohisa
Published: July 2006

Azoxybenzene (1) reacted with dichloro-carbene (2) at 40 °C in the presence of a phase-transfer catalyst (18-crown-6 or tributylamine) in a binary solvent (CHCl3–aqueous KOH), giving 2,2,3,3-tetrachloro-1-phenylaziridine (4), azobenzene (5), and 2-hydroxy-1-phenylbenzimidazole.
Oxidation Products of β-Methyl-substituted δ-Lactones Using Benzeneseleninic Anhydride and Selenium Dioxide
Authors: Matsui Takanao , Tahara Shuji , Nakayama Mitsuru
Published: July 2006

When 9,9-ethylenedioxy-6-methoxycarbonyl-5-methyl-2-oxabicyclo[4.4.0]decan-3-one was treated with benzeneseleninic anhydride and selenium dioxide, the former yielded preferentially the 4,5-dehydrogenated compound (2) together with small amounts of the 5-formyl compound (3) and the contraction product (4) of the δ-lactone ring, while the latter produced solely 2 in a poor yield.
The Mercury Volatilization Rate from Water to the Atmosphere
Authors: Okouchi Shoichi , Sasaki Sokichi , Harano Yoshio
Published: July 2006

The volatilization rate of mercury was studied, together with the oxygen reaeration rate, in a laboratory scale under various mixing conditions. The rates of both mercury and oxygen were controlled by mass transfer in the aqueous phase. The obtained ratio of the mercury-volatilization rate constant to the oxygen-reaeration rate constant was 0.94 at temperatures ranging from 283 to 303. If the oxygen-reaeration rate constant is available in a real-water body or in a wastewater-treatment facility, multiplying its value by the ratio of 0.94 permits the determination of the volatilization rate constant of mercury without the direct measurement of the mercury.
Preferred Orientation of Particles in Reflection-type Powder Diffractometry. Preferred Orientations in Benzamide and α-2-Pyrazinecarboxamide Powders
Authors: Nakata Kazuaki , Sugihara Hiroshi , Mori Shinya , Yamaguchi Hiroshi , Takaki Yoshito
Published: July 2006

An improved method for the determination of the orientation distribution function of a powder consisting of preferentially oriented plate-like and needle-like particles was reported. Using this method, the coarse and fine powders of benzamide and α-2-pyrazinecarboxamide were investigated. It was found that the domains (a domain is defined as a collection of particles having the same preferred orientation plane or axis) of preferentially oriented particles exhibit two distinct changes when undergoing grinding of the powder. One change involves a decrease and the other an increase in volume, indicating that the particles in the domain showing the former change transform into those in the domain showing the latter change following grinding. The increase in volume of the domain can be well explained in relation to the existence of molecular layers connected to each other by weak van der Waals force in the crystal.
Pulse Radiolysis of Cycloserine in Aqueous Solutions. One-Electron Oxidation by OH Radicals
Authors: Tanaka Masako , Sakuma Hiroshi , Kohanawa Osamu , Fukaya Seijun , Katayama Meiseki
Published: July 2006

The reaction of (R)-4-amino-3-isoxazolidinone (cycloserine) with OH radicals was studied in aqueous solutions by optical pulse radiolysis at pHs 6.5–12. It was concluded, from a comparison of the transient spectra with those obtained in a reaction with N3 radicals, that OH radicals attacked at the dissociated peptide group, –N−CO–, and an oxidized radical, –\dotNCO–, was produced through one-electron oxidation. From a kinetic analysis, the reaction was considered to have proceeded by two steps: The first step was the formation of OH adducts, where the rate constant, k(OH+cycloserine), was 8×109 mol−1 dm3 s−1 for the zwitterion form of cycloserine at pH 6.5 and 1.2×1010 mol−1 dm3 s−1 for anion form at pHs 8–10. The second step was the formation of oxidized radicals at a rate of 3–4×106 s−1. These radicals decayed with a second-order rate, suggesting a radical-radical recombination. d-Serine was detected as the major product.
Preparation, Stereochemistry, and Kinetics of Isomerization and Racemization of Acetylacetonato Complexes of Chromium(III) Containing 2,2′-Bipyridine N,N′-Dioxide or Its 3,3′-Dimethyl Derivative
Authors: Kanno Hideaki , Utsuno Shunji , Fujita Junnosuke
Published: July 2006

New acetylacetonato (acac) chromium(III) complexes of the type, [Cr(acac)3−nLn]n+ (n=1 and 2), where L denotes a seven-membered chelate ligand, 2,2′-bipyridine N,N′-dioxide (bpdo) or 3,3′-dimethyl-2,2′-bipyridine N,N′-dioxide (rac- or R-mbdo), were prepared. Optically active [Cr(acac)2(R-mbdo)]+ and [Cr(acac)(R-mbdo)2]2+ yielded only one isomer and were assigned to Δ(λ)(lel) and Δ(λλ)(lel2), respectively, on the basis of the circular dichroism spectra and molecular models. The [Cr(acac)(mbdo)2]2+ complex prepared from rac-mbdo formed two racemates of diastereomers, lel2(Δ(λλ), Λ(δδ)) and lel·ob (Δ(λδ)), Λ(δλ), whereas [Cr(acac)2(bpdo)]+ formed only lel(Δ(λ), Λ(δ)) isomer which was resolved by column chromatography. Both rac- and (−)589[Cr(acac)(bpdo)2](ClO4)2·H2O resolved by a chemical method were found to crystallize in lel2 isomer, but isomerize to the isomer in aqueous solution with the rate of 3.31×10−3 s−1 at 295.2 K, the rate constant for racemization (Δ\ightleftarrowsΛ) being 1.08×10−4 s−1 at 295.2 K. An intramolecular conformational inversion of the bpdo chelate ring for the isomerization and an intramolecular twist mechanism for the racemization were proposed.
Oxygen-plasma Treatment of Packing Materials for Gas Chromatography. The Incorporation of Oxygen into the Hydrocarbon Liquid Phase and the Formation of Crosslinked Products on the Support Surface
Authors: Yamamoto Yukio , Oka Seiji , Hayashi Koichiro
Published: July 2006

The oxygen-plasma treatment of column packings for gas chromatography was examined with diatomaceous earth coated with several kinds of stationary liquid phases from the point of view of the modification of their chromatographic properties. A remarkable effect on the gas chromatograms of polar compounds was observed for the packings with nonpolar liquids, such as squalane and Apiezon L. The elimination of tailing and the improvement of the resolution by the plasma treatment were attributed to the incorporation of oxygen into the hydrocarbon liquids and the formation of crosslinked products covering the adsorptive support surface. These results were compared with the previous data on argon-plasma treatment.
Cycloaddition Reactions of Azepines and Diazepines with Conjugated Double Bonds Possessing Electron-Withdrawing Groups
Authors: Saito Katsuhiro , Iida Shigenori , Mukai Toshio
Published: July 2006

Cycloadditions of 1-ethoxycarbonyl-1H-azepine with 5-methoxycarbonyl-2-pyrone gave [4+2] and [4+6] type adducts and a benzazepine derivative, while the reaction of the azepine derivative with 3-methoxycarbonyl-2-pyrone afforded only a [4+2] type adduct. Similarly, an addition of 1-ethoxycarbonyl-1H-1,2-diazepine with 5-methoxycarbonyl-2-pyrone gave a benzodiazepine derivative. Reactions of the azepine and the diazepine derivatives with tetrachlorocyclopentadienone dimethyl acetal afforded [4+2] type adducts.
Syntheses and Physical Properties of Several Polyphenylenes Containing Mixed Linkages
Authors: Fujioka Yasuhiro
Published: July 2006

Fourteen macrocyclic polyphenylenes, including the following ten new compounds, were synthesized by intra- or intermolecular homo-coupling of di-Grignard compound and by cross-coupling of two kinds of di-Grignard compounds with copper(II) chloride: m,m,o,p,o-pentaphenylene; o,o,p,o,o,p-, m,o,p,m,o,p-, o,p,o,p,o,p-, m,o,p,o,p,o-, m,o,m,o,m,o-, and m,m,m,o,m,o-hexaphenylene; m,o,p,p,o,m,p-, and m,m,m,m,p,o,p-heptaphenylene; and m,o,o,m,o,o,m,o,o,m,o,o-dodecaphenylene. 1H NMR spectra of the polyphenylenes, compared with those of open-chain analogues, provide valuable information on the nonplanar spacial relationship of constituting phenylene rings. UV spectra of the compounds containing p-phenylene ring(s) suggest that the lack or decrease in intensity of K-band above ca. 260 nm or a marked shift of that band provides useful conformational information. Empirical Hückel molecular orbital calculations of longest-wavelength absorption bands of twelve polyphenylenes were also carried out. The calculations furnish additional bases for their conformational aspects deduced from their spectral data and Dreiding stereomodels. IR spectra indicate that lack of intense band(s) near 700 cm−1 may generally be regarded as a piece of plausible evidence for the macrocyclic structure containing no m-phenylene ring. Stabilities of the polyphenylenes to electron bombardment are also discussed.
The in situ-Generated Nickel(0)-catalyzed Homo-coupling of Alkenyl Halides with Zinc Powder. A Specific Outcome in Stereochemistry
Authors: Takagi Kentaro , Mimura Harutaka , Inokawa Saburo
Published: July 2006

The catalytic activity of nickel(0) generated in situ from nickel(II) salt was examined in a dehalogenative coupling of alkenyl halides with zinc powder. The reaction of alkenyl bromides took place provided that potassium iodide was present to assist the reduction of nickel(II) with zinc powder, and also to convert the alkenyl bromides to the corresponding alkenyl iodides. A speculative view concerning the disproportionation step is advanced in an attempt to explain the unique stereochemistry observed.
Syntheses of 23-Dialkylamino-23-deoxydemycinosyltylosins and Conformational Study of Mycaminosyl Tylonolide by Nuclear Overhauser Difference Spectroscopy
Authors: Sakamoto Shuichi , Tsuchiya Tsutomu , Miyake Toshiaki , Tanaka Akihiro , Umezawa Sumio
Published: July 2006

23-Dialkylamino-23-deoxydemycinosyltylosins have been prepared by treating 23-deoxy-23-iododemycinosyltylosin (2) with a series of amines including dimethylamine, diethylamine, and piperidine. 14(23)-Unsaturated derivatives, 23-deoxy-14(23)-enomycaminosyl tylonolide (17) and 23-deoxy-14(23)-enodemycinosyltylosin (4) have also been prepared. The conformation of mycaminosyl tylonolide dissolved in chloroform-d was determined by nuclear Overhauser difference spectroscopy, revealing that the two three-member groups of H(10), Me(22), and H(14) and of H(11), H(13), and H(15) stood, respectively, in a line in this order.
Molecular Structure of [2]Paracyclo[2](2,5)furanophane
Authors: Hama Fumio , Kai Yasushi , Yasuoka Noritake , Kasai Nobutami
Published: July 2006

The molecular structures of [2]paracyclo[2](2,5)furanophane (1) at 20 °C and −150 °C have been determined by means of X-ray diffraction. The crystal is tetragonal, with a=15.996(1), c=8.374(1)Å (at 20 °C), and a=15.823(3), c=8.330(3)Å (at −150 °C), space group P\bar421c and Z=8. The structures were solved by the direct method, and refined anisotropically by the block-diagonal least-squares procedure: R=0.069 and 0.075 for the structures at 20 °C and −150 °C, respectively. The furan ring has an envelope form, and the benzene ring boat-shape.
Coexistence of Hydrogen Atom Transfer Reactions through and not through Triplet Ion Pair between p-Chloranil and Durene
Authors: Kobashi Harumichi , Funabashi Masa-aki , Kondo Tomoyuki , Morita Toshifumi , Okada Tadashi , Mataga Noboru
Published: July 2006

Mechanisms of hydrogen atom abstraction reactions by triplet state p-chloranil (3CA) from durene (DH) were studied by picosecond and nanosecond laser photolysis and transient photoconductivity measurements. 3CA was quenched by DH through diffusional encounter to form a triplet ion pair (IP) between CA and DH, p-chloranil semiquinone radical (CAH·), and 2,4,5-trimethylbenzyl radical (D·). Ionic dissociation of IP was observed in 1,2-dichloroethane (DCE) as well as in acetonitrile. However, no transient species was observed by direct excitation of a charge-transfer (CT) band of the electron donor-acceptor (EDA) complex between CA and DH. The H-atom transfer leading to production of CAH· was found to proceed through two distinct mechanisms; H-atom transfer via IP (Mechanism I) and a more rapid transfer competing with IP formation (Mechanism II). The quantum yields of CAH· produced by Mechanisms I and II and the first-order rate constants for proton transfer, ionic dissociation, and intersystem crossing competing with one another in the IP state were estimated to be (0.1 and 0.2) and (2, 5, and 13)×106 s−1, respectively, in DCE at room temperature.
Structural Study of Germanate Glasses by 119Sn Mössbauer Spectroscopy
Authors: Nishida Tetsuaki , Katada Motomi , Takashima Yoshimasa
Published: July 2006

Mössbauer study of potassium germanate glasses containing a small amount of Sn4+ has been performed to know the relationship between the abnormal composition dependence of physical properties, so-called germanate anomaly, and the local structural change of the glasses. Distinct increases in isomer shift and linewidth and a distinct decrease in quadrupole splitting are observed when the concentration of alkali oxide exceeds about 16 mol%. These changes are ascribed to the formation of nonbridging oxygen atoms in GeO4 units. This is also supported by a drastic decrease in a parameter of intermolecular force constant obtained from the temperature dependence of Mössbauer absorption area. The composition dependence of the parameter is well consistent with that of glass transition temperature (Tg) of the same samples. Transformation of GeO4 tetrahedra into GeO6 octahedra is also confirmed by increases in the parameter of intermolecular force constant and in Tg in the alkali content region lower than 16 mol%. The role of Sn4+ is concluded to be a network modifier which is present at an interstitial site of three-dimensional network composed of GeO4 and GeO6 units.
Vibronic-Level Dependence of the Radiative Decay Rate in Pyrazine and Pyrimidine Vapors: Re-examination under High Spectral Resolution
Authors: Sekiguchi Osamu , Ohta Nobuhiro , Baba Hiroaki
Published: July 2006

The radiative decay rate constants (kF) for vibronic levels in S1 of pyrazine and pyrimidine were derived by using the quantum yields measured under the conditions of SVL excitation. The vibronic level dependence of kF in pyrazine can be explained by the Herzberg-Teller theory.
Orbital Phase Explanation of Regioselectivity of Organic Reactions
Authors: Inagaki Satoshi
Published: July 2006

The regioselectivity of such fundamental organic reactions as electrophilic addition to olefins, Diels-Alder cycloaddition, and electrophilic aromatic substitution, can be explained by the phase continuity-discontinuity properties of orbitals involved in cyclic interaction for acyclic delocalization of electrons.
Dinuclear Cobalt(II) Complexes with Various Dinucleating Ligands and Their Dioxygen Complexes
Authors: Suzuki Masatatsu , Kanatomi Hajime , Murase Ichiro
Published: July 2006

Various types of dinuclear cobalt(II) complexes, [Co2L(CH3COO)2]ClO4, [Co2L(CH3COO)](ClO4)2, [CO2L(OH)](ClO4)2, [Co2L(C3H3N2)]ClO4)2(C3H3N2−)=pyrazolate), and [CO2LX2](ClO4)n, were prepared, where HL represents 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-methylphenol(Hbpmp), 2,6-bis[N-(2-pyridylmethyl)-2-(2-pyridyl)ethylaminomethyl]-4-methylphenol(Hbpmep), 2,6-bis[bis[2-(2-pyridyl)ethyl]aminomethyl]-4-methylphenol(Hbpmep), and 2,6-bis[bis(2-benzirnidazolylmethyl)aminometnyl]-4-metnylphenol(Hbbimp), and X is N3−, NCS−, Cl−, Br−, H2O, or py(pyridine). The electronic spectra and magnetic moments of the complexes revealed that [Co2L(CH3COO)2]ClO4 (L=bpmp, bpmep, or bpep) are high-spin octahedral, whereas the other complexes have five-coordinate structure of high-spin configuration. Some of the bpmp and the bpmep complexes reacted reversibly with molecular oxygen more or less. The P1⁄2 of some complexes were determined spectrometrically. The oxygen affinities of the complexes are highly dependent on the natures of the dinucleating ligands and additional bridging or unidentate ligands.
Studies of Unusual Amino Acids and Their Peptides. XV. The Chemistry of N-Carboxymethyl Amino Acids. III. The Synthesis of N-Tosyl-N-carboxymethyl Amino Acid Derivatives by N-Alkoxycarbonylmethylation
Authors: Miyazawa Toshifumi , Yamada Takashi , Kuwata Shigeru
Published: July 2006

The alkoxycarbonylmethylation of the amide nitrogen of N-tosyl amino acid esters with iodoacetic acid esters in the presence of silver(I) oxide in N,N-dimethylformamide afforded the corresponding N-tosyl-N-carboxymethyl amino acid esters in good yields without racemization of the amino acids.
Kinetic Study of Proton Tunneling in the Reaction between 2,4,6-Trinitrotoluene and 1,8-Diazabicyclo[5.4.0]undec-7-ene in Benzonitrile
Authors: Sugimoto Naoki , Sasaki Muneo , Osugi Jiro
Published: July 2006

The proton tunneling has been examined for the reaction between 2,4,6-trinitrotoluene and 1,8-diazabicyclo[5.4.0]undec-7-ene in benzonitrile in view of the solvent effect on the rate ratio kH⁄kD as well as on the various activation parameters. The reaction rate ratio kH⁄kD diminishes from 18.3 at 15 °C to 14.5 at 35 °C. The difference in the activation energies EaD–EaH is 8.8 kJ mol−1 and the ratio of Arrhenius preexponential factors is 2.5. All these values are greater than the semiclassical limits of the primary kinetic isotope effects. According to Bell’s equation the remarkable isotope effect is due to considerable contribution from tunneling in benzonitrile. The present results, being compared with those in other aprotic solvents, are discussed in relation with the effects of solvent polarity, specific acid–solvent interaction, and geometrical bulkiness in the vicinity of the reaction site.
The Reactions of (Trichlorostannato)rhodates(III) with Trichlorostannate(II) in Hydrochloric Acid Solutions
Authors: Iwasaki Shigemi , Nagai Takashi , Miki Eiichi , Mizumachi Kunihiko , Ishimori Tatsujiro
Published: July 2006

(Trichlorostannato)rhodate(III) complexes, [(CH3)4N]3[RhCln(SnCl3)6−n] (n=2, 3, and 4), reacted with tin(II) in hydrochloric acid solutions to form a purple species. This purple species is assumed to be [RhI(SnCl3)5]4−. The formation reaction of the purple species involved two independent paths, fast and slow paths. The main path was the fast one, in which the reactant mixture was in equilibria among [RhCl3(SnCl3)3]3−, [RhCl2(SnCl3)4]3−, [RhCl(SnCl3)5]3−, and probably [Rh(SnCl3)6]3−. The reaction orders in the formation of the purple species were 1, 2, and −2 with respect to the concentrations of the total rhodium(III) complexes, SnCl3−, and Cl− respectively. The absorpton spectra of the reactant mixture showed an interaction absorption between [RhCl2(SnCl3)4]3− and SnCl3−.
Acylations of 2,2-Dimethyl-2H-chromenes
Authors: Yamaguchi Seiji , Yamamoto Satoru , Abe Shoichi , Kawase Yoshiyuki
Published: July 2006

Orientation in acylation reactions of 2,2-dimethyl-2H-chromenes was studied. Five acetylchromenes were obtained with two methods and six formylchromenes were obtained with a third method. Demethylation of four acyl-methoxy-substituted chromenes gave the corresponding acylchromenols. 2,2-Dimethyl-2H-chromene-6-carboxylic acid (anofinic acid) was also obtained by oxidation of 6-formylchromene.