bluuebunny/crossref_metadata_2025 huggingface dataset:
Nucleophilic Desulfinylation of α-Fluoro-β-(alkoxy and silyloxy) Sulfoxides.Effects of the β-Oxy Substituents on Protonation, 1,2-Hydrogen Migration, and Nucleophile Addition to the Fluorocarbenoid Centers
Authors: Uno Hidemitsu , Sakamoto Katsuji , Suzuki Hitomi
Published: July 2006

Treatment of 2-(4-biphenylyl)-2-t-butyldimethylsilyloxy-1-chloro-1-fluoroethyl phenyl sulfoxide with PhMgBr resulted in the formation of a fluorostilbene derivative, a fluoro enol silyl ether and small amounts of 4-(fluoroacetyl)biphenyl, while a similar reaction of 2-methoxymethoxy analog mainly led to the fluorostilbene derivatives and a simple desulfinylation product. In contrast, both sulfoxides reacted with PhLi to give chlorofluoro compounds and fluoro enol ethers. In these reactions, the stability of carbenoids derived from the nucleophilic removal of the sulfoxide moiety was greatly affected by the β-substituents, thus controlling the product distributions.
Electrochemical Investigations of High-Spin (10,20-Diaryletioporphyrinato II) Iron(III) Complexes
Authors: Kijima Masashi , Akimoto Kei , Sakawaki Akira , Sato Takeo
Published: July 2006

The redox behaviors of high-spin (10,20-diaryletioporphyrinato II) iron(III) complexes were investigated by cyclic voltammetry in both anodic and cathodic regions in dichloromethane. Whether the redox waves are due to a porphyrin-ring-centered reaction or a metal-centered reaction was examined in terms of the spectroelectrochemical results and Hammett reaction constants.
One-Color and Two-Color Resonance-Enhanced Two-Photon Ionization Studies of Benzene: Sudden Drop of Photoionization Yield at the Onset of the Third Channel Region
Authors: Ichimura Teijiro , Shinohara Hisanori , Ohashi Kazuhiko , Nishi Nobuyuki
Published: July 2006

Benzene molecules in a supersonic jet were photoionized using a tunable (233–262 nm) pulsed dye laser, and the resonance-enhanced two-photons ionization (RE2PI) processes of the S1 state were investigated by time-of flight (TOF) mass-spectrometric technique. Without further fragmentation of C6H6+ ions under low laser power conditions (< 20 μJ/pulse), high-resolution excitation spectra of the parent ion have been measured for the 611n progression (n = 0,1,2,3). The relative photoionization intensity suddenly drops at the onset of the third channel band, 6113. Excitations of the rotationally resolved 6113 and 6112 bands under carefully controlled low laser powers have revealed the fact that the relative intensity of the 6113 band (above 3rd channel) to that of the 6112 band (below 3rd channel) decreases with decreasing the excitation laser power. This has confirmed the idea that the ionizing process is competing with nonradiative relaxation processes at the resonant state. Two-color RE2PI excitation with the pumping (ω1) and electrically delayed probing (ω2 = 272.0 nm) lasers has given population decay rates of vibronic state longer than 20 ns. Excitation spectra of the parent ion with scanning ω1 (241–248 nm) and those with the optically delayed (2.8–8.0 ns) fixed wavelength of ω2 have been observed. Relative population yields for the 71 and 6113 vibronic states drastically decreased in a similar fashion to the relative fluorescence yield for the longer delayed excitation. The present RE2PI measurement of the relative population yields for selective vibronic band excitations revealed that the ionization method can detect the non-fluorescent transient species produced the optical excitation above the 3rd channel of the S1 state of benzene.
Preparation of Bis(phthalocyaninato)lutetium with Various Substituents and Their Electrochemical Properties
Authors: Liu Yunqi , Shigehara Kiyotaka , Yamada Akira
Published: July 2006

A series of bis(phthalocyaninato)lutetium complexes with substituents on each benzoring [Lu(pc2R8)] was prepared and the electrochromic behavior investigated by means of cyclic voltammetry of coated electrodes.

Although the unsubstituted complex, Lu(pc)2, showed multistep electrochromism, its stability was quite unsatisfactory due to a falling-off of films from the electrode surface upon repetitive potential scanning. In the case of R = t-butyl, the improved solubility in organic solvents brought about an easier filming process and better adhesion to the electrode surface, though its high oxidation potential caused a cleavage of bi-peripheral complex. In contrast, complexes with electron-donating groups, such as R = propoxy or neopentyloxy, showed a lower oxidation potential and better stability upon repetitive potential scans, though the oxidized color was brownish rather than bright red. Complexes with 4 groups each of tetra-t-butyl and tetra propoxy had the oxidation potential close to that of octapropoxy or octakis(neopentyloxy) complexes and showed much improved stability and electrochromic behavior.
Reduction of Dicarboxylic Acid Anhydride with 2-Propanol over Hydrous Zirconium Oxide
Authors: Takahashi Kyoko , Shibagaki Makoto , Matsushita Hajime
Published: July 2006

The reduction of dicarboxylic acid anhydrides with 2-propanol proceeded efficiently over hydrous zirconium oxide to give the corresponding lactones and cyclic ethers. Secondary and primary alcohols, with the exception of methanol, are able to act as hydride donors in this reduction. The reduction proceeded as nearly second order concerning the concentration of 2-propanol and minus order concerning that of acid anhydride. These results suggest that the reduction was preferred under lower concentrations of acid anhydride and higher concentrations of 2-propanol. The selectivity of lactone or ether could be changed by the reaction temperature or the molar ratio of dicarboxylic acid anhydride to alcohol.
Optical Resolution by Replacing Crystallization of (RS)-4-Thiazolidinecarboxylic Acid with l-Amino Acids as Cosolute
Authors: Shiraiwa Tadashi , Yamauchi Masahiro , Tatsumi Takeshi , Kurokawa Hidemoto
Published: July 2006

The optical resolution by replacing crystallization of (RS)-4-thiazolidinecarboxylic acid [(RS)-THC] was carried out with coexisting eight l-amino acids and the effect of the latter was examined. l-Isoleucine [l-Ile] and l-cysteine [l-Cys] as the cosolute led to preferential crystallization of (R)-THC from an aqueous solution of (RS)-THC, whereas the other l-amino acids gave (S)-THC. l-Cys, l-threonine, l-4-hydroxyproline [l-Hyp], and l-serine as the cosolute seemed to give better selectivity for crystallization of one enantiomer than l-Ile, l-valine, l-proline, and l-alanine. The optical resolution with l-Hyp was successfully achieved and suggested a possibility of successive optical resolution to give both (R)- and (S)-THC.
Aromatization of Ethylene and C4 Hydrocarbons Using a Thermal Diffusion Column
Authors: Takagi Yuzuru , Aoyagi Toshiaki , Yoshida Takeo , Yada Satoru , Yamaguchi Tatsuaki , Esumi Yasuaki , Tanaka Kazunori
Published: July 2006

Thermal diffusion columns, consisting of water-cooled glass tubes and a coaxial red-hot metal wire, were applied as the reactor to dehydrogenative coupling of ethylene or C4 hydrocarbons. This application was intended to separate hydrogen spontaneously from other products, especially from aromatics, leading to enhanced yields. Hydrogen gas would ascend the red-hot wire, while the aromatics would descend the cold glass walls. When the metal wire was actually red-hot in the reactant hydrocarbon flow, oily products were really formed, most of which were mono- and bicyclic aromatic compounds such as benzene, styrene, and naphthalene. Product distributions were measured for different reactant species, wire metals, wire temperatures, and a few additional variables. Especially notable was the selective formation of 4-vinyl-1-cyclohexene from 1,3-butadiene at relatively low temperatures near 600 °C.
The Raman Active Intra- and Intermolecular Vibrations of [1H10]- and [2H10]p-Xylenes
Authors: Nakamura Seijiro , Sonoda Yoshitaka , Tominari Shigenori , Nibu Yoshinori , Shimada Hiroko , Shimada Ryoichi
Published: July 2006

Assignment of the Raman active normal vibrations of [1H10]- and [2H10]p-xylenes was made through the vibrational analysis of the polarized Raman spectra. Assignment of the low-frequency Raman bands to the rotational intermolecular vibrations of the crystals was also discussed.
Cobalt(III) Complexes with Quadridentate Ligands. XI.The Preparation and Properties of cis-α-Isomer of the Salicylato(triethylenetetramine)cobalt(III) Complex
Authors: Yamamoto Yoshihisa , Toyota Eiko , Kumon Toyo , Sekizaki Haruo
Published: July 2006

cis-α-Salicylato(triethylenetetramine)cobalt(III) chloride, cis-α-[Co(sal)trien]Cl, has been isolated and characterized by means of both analytical and spectroscopic methods.
Micellar Effect on the Formation Rate of Ni(II) and Co(II) Complexes with 8-Quinolinol and Its 5-Alkyloxymethyl-8-quinolinol Derivatives in a Nonionic Surfactant Micellar System
Authors: Tagashira Shoji , Onoue Kouichi , Murakami Yoshiko , Sasaki Yoshiaki
Published: July 2006

In the Triton X-100 micellar system, ligands such as 8-quinolinol and 5-alkyloxymethyl-8-quinolinol were distributed between the aqueous and micellar phases. The Ni(II) and Co(II) complexes were formed in both phases and their reaction rate constants in the aqueous phase were 2.8 × 103 and 1.3 × 105 mol−1 dm3 s−1, respectively. The reaction rates in the micellar phase were about one-tenth those in the aqueous phase. The distribution of ligand into the micellar phase delayed the observed reaction rate.
Selective Separation of Yttrium Ions from Other Rare Earth Ions Using Nonequilibrium Extraction
Authors: Minagawa Yukinori , Yajima Fumikazu
Published: July 2006

An advanced new method for the separation of yttrium ions from other rare earth ions using nonequilibrium extraction in the DTPA–B2EHPA system has been demonstrated. The extraction stages for obtaining yttrium oxide of 99.9% purity from yttrium oxide of 60% purity as a starting material were estimated to be about fifteen, which was the smallest value ever obtained, compared with the usual method (50–100 stages). The mechanism of the extraction reaction is discussed.
Stereoselectivities in Catalytic Hydrogenation of Several Branched-Chain 6-Deoxyhex-5-enopyranosides.A Synthesis of Branched-Chain Methyl 6-Deoxy-β-l-hexopyranoside
Authors: Sato Ken-ichi , Sakuma Shogo , Takahashi Kazuo , Hashimoto Hironobu
Published: July 2006

Hydrogenation of several 2-C, 3-C, and 4-C-methyl-branched 6-deoxyhex-5-enopyranosides in the presence of palladium–carbon in ethanol showed stereoselective formation of the corresponding 6-deoxy-β-l-hexopyranosides.
Reactions of 3-Isopropenyl- and 3-Acetyltropolone with Quarternary Ammonium Tribromides
Authors: Matsunaga Yoichiro , Imafuku Kimiaki
Published: July 2006

Treatments of 3-isopropenyltropolone with quarternary ammonium tribromides in tetrahydrofuran afforded 3-methyl-8H-cyclohepta[b]furan-8-one. The reactions in methanol–dichloromethane gave 7-bromo-3-methyl-8H-cyclohepta[b]furan-8-one. Bromination of 3-acetyltropolone with the tribromides in tetrahydrofuran produced 3-(bromoacetyl)tropolone, while the reaction in the methanolic solvent gave 7-bromo- and 5,7-dibromo-substituted 3-acetyltropolones. The brominations of 4′-hydroxyacetophenone were also carried out.
1,2-Addition of Allyl and 2-Oxo-2H-pyran-6-ylcarbonyl Groups to Cyclic C=N Double Bonds by Means of Organotin Reagent for Alkaloids Synthesis; A Facile Synthesis of 8-Oxoprotoberberine and Norketoyobirine (Demethoxycarbonyloxogambirtannine)
Authors: Yamaguchi Ryohei , Otsuji Atsuo , Utimoto Kiitiro , Kozima Sinpei
Published: July 2006

1,2-Introduction of allyl and 2-oxo-2H-pyran-6-ylcarbonyl groups into isoquinoline system can be effectively accomplished by reaction of allyltributyltin with 3,4-dihydroisoquinoline activated by 2-oxo-2H-pyran-6-ylcarbonyl chloride. Allyltributyltin reacts similarly with 3,4-dihydro-β-carboline activated by 2-oxo-2H-pyran-6-ylcarbonyl chloride to gave the corresponding 1,2-adduct. Intramolecular Diels–Alder reactions of the 1,2-adducts followed by DDQ oxidations afford 8-oxoprotoberberine and norketoyobirine.
2,3-Dichloro-5,6-dicyano-p-benzoquinone as a Mild and Efficient Catalyst for the Tetrahydropyranylation of Alcohols
Authors: Tanemura Kiyoshi , Horaguchi Takaaki , Suzuki Tsuneo
Published: July 2006

Hydroxy compounds readily add to 3,4-dihydro-2H-pyran under neutral conditions in the presence of a catalytic amount of 2,3-dichloro-5,6-dicyano-p-benzoquinone, to give high yields of the corresponding tetrahydropyranyl ethers.
Direct Iodination of Aromatic Compounds with Iodine and Alumina-Supported Copper(II) Chloride or Sulfate
Authors: Kodomari Mitsuo , Amanokura Natsuki , Takeuchi Kiyoshi , Yoshitomi Suehiko
Published: July 2006

The iodination of aromatic compounds (polymethylbenzenes, alkyl phenyl ethers, and polynuclear aromatic hydrocarbons) with iodine in combination with copper(II) chloride or sulfate supported on alumina proceeds well under mild conditions to selectively give monoiodinated compounds in high yields.
The Calculation of Temperature and Thermal Stress Distributions in the Planar Solid Oxide Fuel Cell
Authors: Kanamura Kiyoshi , Yoshioka Shoji , Takehara Zen-ichiro
Published: July 2006

The temperature and thermal stress distributions in a planar solid oxide fuel cell (SOFC) were calculated using a finite element method in order to determine guidelines for the selection of cell materials. The calculations indicate that the thermal stress is generated in a planar SOFC composed of yttria stabilized zirconia (YSZ) electrolyte, a LaMnO3 cathode, and a Ni-YSZ cermet anode. The largest stress is generated in the region of the cathode material. According to the calculations, if the linear expansion of the cathode material is 1.0 × 10−6 (the linear expansion of porous LaMnO3 is 2.0 × 10−5), the thermal stress in the SOFC will be relieved.
Determination of the Dimerization Constant in Self-Associating Systems
Authors: Hada Sakae , Neya Saburo , Funasaki Noriaki
Published: July 2006

The self-association of Methylene Blue (MB), a cholic acid derivative, chlorpromazine hydrochloride (CPZ), and octaethylene glycol decyl ether has been investigated by frontal gel filtration chromatography (GFC) and spectrophotometry at 25 °C. The stepwise aggregation constant ki is estimated as a function of aggregation number i from the centroid volume Vc of the GFC profile by using appropriate association models. The dimerization constants k2 for MB and CPZ determined by spectrophotometry are close to those from Vc values. The dimerization constants are also estimated from the concentration dependence of the peak volume Vp of the derivative GFC profile. The k2 values determined from the Vp values are slightly larger than those from the Vc values. This discrepancy is ascribed to the approximation of the Vp approach. The minimum multimerization concentration (mmc), above which multimers higher than trimer are formed, is determined from each of Vc, Vp, and absorption spectral measurements. The relation between mmc and the critical micelle concentration (cmc) depends on the degree of criticalness of cmc. This degree of criticalness increases as the aggregation number at the maximum ki value increases.
Kinetics and Mechanism of the High Temperature Selenidization of Cobalt
Authors: Takahashi Kazuhiro , Sasaki Yoshinori
Published: July 2006

A cobalt sheet was selenidized in selenium vapor of 1.33–13.33 kPa at 823–973 K by means of a sealed-tube method. X-Ray diffraction patterns and an electron probe microanalysis of the product films showed that double layers composed of thin outer CoSe2 and thick inner Co3Se4 were formed under all the reaction conditions employed. All the selenidizations obeyed a parabolic rate law and therefore the rate-determining step was apparently a diffusion process. The parabolic rate constant, Kp, was expressed as a function of the absolute temperature. The pressure dependence of Kp was not clearly recognized. A marker experiment indicated that cobalt was the component which diffused.
Binuclear Nickel(II) Complexes of Schiff Bases Derived from Salicylaldehydes and 1,n-Diamino-n′-hydroxyalkanes (n,n′ = 3,2; 4,2; and 5,3) Having an Endogenous Alkoxo Bridge and a Pyrazolato Exogenous Bridge
Authors: Mikuriya Masahiro , Sasaki Tomoko , Anjiki Atsushi , Ikenoue Shuichi , Tokii Tadashi
Published: July 2006

μ-Alkoxo-μ-pyrazolato-bridged binuclear nickel(II) complexes with 1,3-bis(salicylideneamino)-2-propanol (H3La), 1,4-bis(salicylideneamino)-2-butanol (H3Lb), and 1,5-bis(salicylideneamino)-3-pentanol (H3Lc), Ni2(La)(pz), Ni2(Lb)(pz), and Ni2(Lc)(pz) (pz = pyrazolate anion), have been prepared and characterized by elemental analyses, infrared and electronic spectra, and magnetic susceptibilities. The molecular structures of these complexes were determined by the single-crystal X-ray structure analyses. The planarities of the molecules were discussed in relation to the variation of the chain lengths of the Schiff bases.
Synthesis and Some Reactions of 2-Amino-1-azaazulene-3-carbaldehyde
Authors: Abe Noritaka , Tanaka Keiko , Yamagata Satoshi , Satoh Akira , Yamane Kameji
Published: July 2006

2-Chloro-1-azaazulene-3-carbaldehyde (1a) reacted with pyridine, followed by a reacion with piperidine to give 2-amino-1-azaazulene-3-carbaldehyde (1b) in excellent yield. Compound 1b was also obtained by a Vilsmeier–Haack reaction of 2-amino-1-azaazulene. Acetylation of 1b yielded a 2-acetylamino derivative, whereas methylation gave a 1-methylated compound. Reactions of 1b with hydrazines and alkylamines gave the corresponding hydrazones and Schiff bases, respectively, in excellent yields. The reactions of 1b with active methylene compounds gave 1,10-diazabenz[a]azulen-2(1H)-one derivatives. The reaction of 1b with guanidine gave pyrimidine-fuzed 1-azaazulene.
Photobromination of Side-Chain Methyl Groups on Arenes with N-Bromosuccinimide–Convenient and Selective Syntheses of Bis(bromomethyl)- and (Bromomethyl)methylarenes–
Authors: Futamura Shigeru , Zong Zhi-Min
Published: July 2006

Photobromination of side-chain methyl groups on arenes with N-bromosuccinimide (NBS) was investigated. Visible light irradiation in benzene solvent was extremely effective in increasing the selectivity of the reaction and the efficiency for product purification. The photobromination of 1,4-, 1,8-, 2,3-, and 2,6-dimethylnaphthalenes, 4,4′-dimethylbiphenyl, and p-xylene with 2.2 mol equivalents of NBS quantitatively afforded the corresponding bis(bromomethyl)arenes, respectively. The (bromomethyl)methylarenes were also obtained in good yields in the photobromination reactions of the above dimethylarenes with 1.1 mol equivalents of NBS.
Isomerization of Olefins by Means of R3SnH–Et3B and Stereochemical Study on Reduction of Alkenyl Iodides
Authors: Taniguchi Masahiko , Nozaki Kyoko , Miura Katsukiyo , Oshima Koichiro , Utimoto Kiitiro
Published: July 2006

Isomerization of olefins with R3SnH–Et3B (R = Ph or n-Bu) system has been studied. Treatment of (Z)-1-triphenylstannyl-1-octene (1) or (E)-1-triphenylstannyl-1-octene (2) with a catalytic amount of Ph3SnH–Et3B provided an equilibrium mixture of 1/2 = 2/8. Partial isomerization was observed in the reaction of trivial alkenes such as 6-dodecene and 2,2-dimethyl-3-dodecene with R3SnH–Et3B system. Whereas (Z)- or (E)-6-dodecene was recovered unchanged upon treatment with n-Bu3SnH–Et3B at −78 °C for 3 h, stirring a benzene solution of (Z)-6-dodecene, Ph3SnH, and Et3B at 60 °C for 5 h gave an isomeric mixture of (Z)-6-dodecene and (E)-6-dodecene (Z/E = 64/36). Taking account of these results, the stereochemistry of the reduction of alkenyl iodides at −78 °C with R3SnH–Et3B system was studied. 6-Dodecenyl radical proved to isomerize much more rapidly than it abstracts a hydrogen from R3SnH.
MO Analysis of Photocycloaddition Reactions of 2-Pyrones
Authors: Somekawa Kenichi , Shimo Tetsuro , Suishu Takaaki
Published: July 2006

The skeleton of the 2-pyrones (1) is a simple one composed of 2,4-pentadien-5-olides, but has many possibilities for photocycloadditions. To elucidate the peri-, site-, and regioselective photoadditions of the triplet 2-pyrones with some ethylenes, the factors were analyzed by PM3-CI-UHF methods, etc. The regioselective [4+2]cycloadducts (3) and site-selective [2+2]cycloadducts (4) across the C5–C6 double bonds of the 2-pyrones with electron-deficient ethylenes were deduced to be formed by their preferable HSOMO–LUMO interactions and via more stable biradicals by the C6-Cβ bondings. On the other hand, the other kinds of regioselective [4+2] (6) and [2+2]adducts (5) across the C3–C4 double bonds of the 2-pyrones with an electron-donating ethylene were inferred to mainly come from LSOMO–HOMO interactions and via biradicals by C3-Cβ bondings. Selectivities between 3 and 4, and 5 and 6 were also inferred to be caused by SOMOs of the biradicals.
A Practical Synthesis of threo-3-Amino-2-hydroxycarboxylic Acids
Authors: Matsuda Fuyuhiko , Matsumoto Teruyo , Ohsaki Masako , Ito Yoshio , Terashima Shiro
Published: July 2006

An expeditious synthesis of (2R,3S)-3-amino-4-cyclohexyl-2-hydroxybutyric acid (2) and (2S,3R)-3-amino-2-hydroxy-4-phenylbutyric acid (4), the key components of the renin inhibitor (1) and bestatin (3), respectively, have been accomplished by featuring highly diastereoselective formation of cyanohydrin acetates from α-alkoxycarbonylamino aldehydes under phase-transfer conditions.
A Chiral Synthesis of d-myo-Inositol 1-Phosphate Starting from l-Quebrachitol
Authors: Akiyama Takahiko , Takechi Naoto , Ozaki Shoichiro , Shiota Kenji
Published: July 2006

A naturally occurring optically active cyclitol, l-quebrachitol (1l-2-O-methyl-chiro-inositol), was stereoselectively transformed into myo-inositol derivatives via an oxidation-reduction process. The methyl ether was cleaved chemoselectively with AlCl3–NaI in the presence of a cis-cyclohexylidene moiety with d-myo-inositol 1-phosphate being efficiently obtained.
Hydrolytic Metalloenzyme Models. Metal Ion Dependent Site-Selective Acylation of Hydroxyl Groups of Bis-Imidazole Ligands Catalyzed by Zn2+ and Cu2+ in the Reaction with p-Nitrophenyl 2-Pyridinecarboxylate in a Cationic Surfactant Micelle
Authors: Ogino Kenji , Kashihara Nobuyuki , Ueda Toshitomo , Isaka Toshihide , Yoshida Toshiharu , Tagaki Waichiro
Published: July 2006

Co-micelles of hexadecyltrimethylammonium bromide and a lipophilic bis-imidazole ligand, 1-dodecyl-4-hydroxymethyl-α-(1-dodecyl-2-imidazolyl)-2-imidazolemethanol (4) having two primary and secondary hydroxyl groups, together with the co-micelles of the related lipophilic ligands, were investigated for their catalytic activities in the hydrolysis of p-nitrophenyl 2-pyridinecarboxylate (PNPP) in the presence of Zn2+ or Cu2+. The kinetic and product analyses indicated that the reaction proceeds through the transacylation from PNPP to the hydroxyl group of ligand : metal ion complexes and that the active complexes undergoing transacylation are a 2 : 1 and a 1 : 1 complex for Zn2+ and a 1 : 1 complex for Cu2+, respectively. As for the ligand 4, the transacylation was found to be highly site-selective, i.e. it occurred predominantly on the secondary hydroxyl group with Zn2+, while on the primary hydroxyl group with Cu2+, respectively. Such selectivity was discussed in terms of the coordination structures of the active complexes.
Photochromic Properties of 2-Hydroxychalcones in Solution and Polymers
Authors: Matsushima Ryoka , Suzuki Masakazu
Published: July 2006

A series of substituted 2-hydroxychalcones (HC) were prepared, most of which underwent efficient and clean photochemical conversion into flavylium cations (FV) in acidic solution and polymer film, although strongly dependent on the pH and medium conditions as well as the HC structures. 4′-Methoxy and 4′-dimethylamino derivatives showed relatively high thermal stabilities of the colored mixtures, well-separated absorption bands of the HC and FV forms, almost quantitative conversion from HC to FV in the photostationary-state mixtures, and good photochromic performances in solution and polymer film, without suffering from the dissolved oxygen or moisture. A few of them showed relatively high reversibilities in the HC–FV interconversions under special pH and medium conditions.
Rate of Back-Extraction of Tris(acetylacetonato)- and Tris(trifluoroacetylacetonato)chromium(III) from Carbon Tetrachloride into Aqueous Acid Perchlorate Solutions
Authors: Sekine Tatsuya , Kubo Tsuyoshi , Suzuki Yasuhiro
Published: July 2006

The rate of back-extraction of tris(acetylacetonato)chromium(III) ([Cr(acac)3]), and tris(trifluoroacetylacetonato)chromium(III) ([Cr(tfa)3]), from carbon tetrachloride into aqueous acid perchlorate solutions was measured. The rate of [Cr(acac)3] was much higher and that of [Cr(tfa)3] was also a little higher in the higher acid concentration range. This was concluded to be due to formation of the [Cr(acac)3(H+)2] and the [Cr(tfa)3H+] species which increased the concentration of the tris-complex species in the aqueous phase. With the both complexes, the rate was not affected by the ligand concentration in the aqueous phase. From these results, the controlling reaction was concluded to be the dissociation of the first ligand from the tris-complex or from the proton associate of the triscomplex in the aqueous phase.
Determination of the Molar Absorption Coefficients of c-Type Cytochromes Using Optically Transparent Thin-Layer Electrodes
Authors: Sagara Takamasa , Koide Tomoyuki , Saito Hiroyuki , Akutsu Hideo , Niki Katsumi
Published: July 2006

The simultaneous monitoring of both the absorbance and charge consumed in electrolysis in a precalibrated Optically Transparent Thin-Layer Electrode (OTTLE) cell was demonstrated as a precise method for determining the molar absorption coefficients of electron-transfer proteins. In this method, the procedure for a direct determination of the concentration of the protein could be omitted. The values of the molar absorption coefficients of c-type cytochromes at the α-peaks of reduced forms were determined by this method: 28.4 mM−1 cm−1 (1 M = 1 mol dm−3) at 550 nm for horse heart cytochrome c, 119 mM−1 cm−1 at 552 nm for cytochrome c3 from Desulfovibrio vulgaris, Miyazaki F, and 116 mM−1 cm−1 at 552 nm for cytochrome c3 from Desulfovibrio vulgaris, Hildenborough.
Synthesis of New Serine-Linked Oligosaccharides in Blood-Clotting Factors VII and IX and Protein Z.The Syntheses of O-α-d-Xylopyranosyl-(1→3)-d-glucopyranose, O-α-d-Xylopyranosyl-(1→3)-O-α-d-xylopyranosyl-(1→3)-d-glucopyranose, and Their Conjugates with Serine
Authors: Fukase Koichi , Hase Sumihiro , Ikenaka Tokuji , Kusumoto Shoichi
Published: July 2006

The di- and trisaccharide sequences and their conjugates with serine recently identified in the first epidermal growth factor-like domain of bovine and human blood-clotting factors VII, IX, and protein Z were synthesized in order to elucidate their biological function. The disaccharide α-d-Xylp(1→3)-d-Glcp was prepared from 2,3,4-tri-O-benzyl-α-d-xylopyranosyl fluoride and allyl 2,4,6-tri-O-acetyl-α-d-grucopyranoside (9a) using tin(II) chloride and silver perchlorate as glycosylating reagents. The trisaccharide α-d-Xylp(1→3)-α-d-Xylp(1→3)-d-Glcp was prepared from O-(2,3,4-tri-O-benzyl-α-d-xylopyranosyl)-(1→3)-2,4-di-O-benzyl-α,β-d-xylopyranosyl fluoride and 9a with the same reagents. Their conjugates with serine, α-d-Xylp(1→3)-β-d-Glcp(1→3)-l-Ser and α-d-Xylp(1→3)-α-d-Xylp(1→3)-β-d-Glcp(1→3)-l-Ser, were synthesized by the glycosylation of N-benzyloxycarbonyl-l-serine benzyl ester with the corresponding glycosyl trichloroacetimidates of the above saccharides, followed by removal of the protecting groups. The p-nitrobenzyl group, which was recently devised for temporary protection of hydroxyl functions, was used for the 3-hydroxyl group of glucose.
Reactivities of 2-C- and 3-C-Nitro-α- and β-d-erythro-Hex-2-enopyranoside Derivatives towards Methanol and AM1 Studies upon Their Stereoselectivities
Authors: Sakakibara Tohru , Ohkita Noriaki , Nakagawa Toshio
Published: July 2006

The rates of the reactions of six nitro enosides with methanol-d4 in dimethyl sulfoxide-d6 were determined by 1H NMR spectroscopy. Their reactivities and stereoselectivities were discussed including the results of AM1 calculations of model compounds.
Synthesis of Model Compounds of Safflomin C
Authors: Sato Shingo , Obara Heitaro , Onodera Jun-ichi , Endo Akira , Matsuba Shigeru
Published: July 2006

3-[3,3-Dimethyl- and 3-hydroxy-3-methyl-2,4-dihydroxy-5-(4-hydroxycinnamoyl)-6-oxo-1,4-cyclohexadienyl]- 3-(4-hydroxyphenyl)propanoic acid were synthesized as model compounds of safflomin C. Their spectra closely resembled that of safflomin C.
Tigogenin Hexasaccharides from Camassia cusickii.Structural Elucidation by Modern NMR Techniques
Authors: Mimaki Yoshihiro , Sashida Yutaka , Nikaido Tamotsu , Ohmoto Taichi
Published: July 2006

Two steroidal saponins containing six carbohydrate residues have been isolated from the bulbs of Camassia cusickii. Their structures were determined by modern NMR techniques, 1H–1H COSY, HOHAHA, 1H–13C COSY, and HMBC spectra to be (25 R)-5α-spirostan-3β-yl 4-O-[2-O-[3-O-(α-l-rhamnopyranosyl)-β-d-glucopyranosyl]-3-O-[4-O-(α-l-rhamnopyranosyl)-β-d-glucopyranosyl]-β-d-glucopyranosyl]-β-d-galactopyranoside (1) and (25R)-5α-spirostan-3β-yl 4-O-[2-O-[3-O-(β-d-glucopyranosyl)-β-d-glucopyranosyl]-3-O-[4-O-(α-l-rhamnopyranosyl)-β-d-glucopyranosyl]-β-d-glucopyranosyl]-β-d-galactopyranoside (2), respectively. Compound 1 showed inhibitory activity on cyclic AMP phosphodiesterase.
Preliminary Analysis of the Electronic Absorption Spectrum of a Solute in a Biaxially-Stretched Polymer Film
Authors: Kobayashi Michio , Yuan Xinghai , Sakai Haruo , Hoshi Toshihiko , Okubo Jun , Tanizaki Yoshie
Published: July 2006

A biaxially-stretched film method has been proposed and applied for the analysis of the electronic absorption spectrum of a solute embedded in a biaxially-stretched polymer film to demonstrate its usefulness. The intrinsic absorbance change of the solute on biaxial stretching was measured by a ratio (Rbi) of the molar absorptivity (εb) of the solute in the biaxially-stretched film to that (εi) in the nonstretched isotropic film. This Rbi(= εb⁄εi) spectrum was expressed in terms of three orientation factors for three molecular axes of the solute and three absorption components (three-dimensional reduced spectra) purely polarized along the three molecular axes. Problems inherent in this method are discussed by analyzing the Rbi spectra of spherical, disk-like, and rod-like molecules. An approximate estimate of the three-dimensional reduced spectra of a rod-like molecule (pinacyanol, 1-ethyl-2-[3-(1-ethyl-2(1H)-quinolinylidene)-1-propenyl]quinolinium iodide) was obtained by an analysis of its Rbi spectrum by use of orientation factors with the aid of a uniaxially-stretched film method formulated by the use of an orientational distribution function.
Solvent Extraction of Transition Metal Cations by Calixarene-Based Cyclic Ligands
Authors: Nagasaki Takeshi , Shinkai Seiji
Published: July 2006

Calix[n]arenes (n = 4 and 6) bearing carboxyl groups (1n), hydroxamate groups (2n), and dimethylamino groups (3n) on the lower rim and their monomeric analogs (11, 21, and 31) were synthesized to estimate selective extraction of transition metal cations from the aqueous phase to the organic (chloroform) phase. 14 and 16 showed the selectivity toward Fe3+, Cu2+, Zn2+, and Pd2+. In particular, 16 showed the unusually high extractability toward Fe3+. 24 and 26 showed the selectivity toward Fe3+, Cu2+, and Pd2+, but only Fe3+ was extracted to a significant extent at pH 2.2, the order of the extractability being 26 > 24 > 21. 34 and 36 showed the selectivity toward Pd2+ and Pt4+. The detailed examination of the extraction mechanism established that the ion-pair extraction mechanism is operative in Pt4+ (i.e., extracted as [PtCl6]2−) whereas both the ion-pair extraction mechanism and the chelatecomplex extraction mechanism are operative in Pd2+ (i.e., extracted as [PdCl4]2− in the ion-pair extraction mechanism). The results indicate that the ligand groups circularly arranged on the lower rim of the calixarene cavity form novel binding sites for transition metal cations.
Reaction of Synthetic Melanins with Redox Reagents. II.ESR Spectra Using Flow Method
Authors: Oniki Takayuki
Published: July 2006

Electron spin resonance (ESR) spectra of synthetic pyrogallol melanin showed a hyperfine structure at pH 13.0 under anaerobic conditions but did not under aerobic conditions. The outer signal defined in a previous paper was observed in the reactions with hexacyanoferrate(III) at pH 11.5 and with NaIO4 at pH 13.0. The reaction with NaIO4 indicated that the outer signal is splitted into two lines with hyperfine coupling constant (hfcc) of 0.41 mT. Another signal which is splitted into two lines with hfcc of 0.65 mT was observed in the reaction with NaBH4 at pH 13.0. Na2S2O4 solution showed ESR signal under anaerobic conditions and this signal disappeared by a large amount of melanins. The broad signal defined in a previous paper disappeared slowly by Na2S2O4 but did not by NaBH4. Time courses of ESR signal in reactions of melanins with redox reagents were shown up to 30 min after mixing.
Pressure-Dependent Intensity Anomalies in the B2Σ+∼4Π Perturbed Rotational Lines of the CN (B2Σ+-X2Σ+) 14-14 Band
Authors: Kanda Kazuhiro , Ito Haruhiko , Suzuki Kaoru , Kondow Tamotsu , Kuchitsu Kozo
Published: July 2006

The CN(B2Σ+–X2Σ+) 14–14 emission band was observed in the reaction of Ar(3P0,2) with BrCN by the use of the flowing afterglow method. The intensity anomalies in the rotational lines at N′ = 7 due to the B2Σ+(ν = 14)∼4Π(ν = 7) perturbation were measured as a function of the pressure of Ar or He introduced as a collision partner in the reaction region, the ambient pressure being varied from 9 to 2000 mTorr (1 Torr = 133.322 Pa). The intensities of the perturbed lines relative to that of the rotational band envelope increased with the ambient pressure in the low pressure region in the cases of both Ar and He. On the other hand, they decreased with pressure in the higher pressure region. The pressure dependence of the intensity anomaly for He followed that for Ar, although higher pressure of He was necessary to attain the same level of the intensity anomaly for Ar. These pressure dependences can be explained semiquantitatively by a model with collisional rotational relaxations in the quartet and doublet manifolds, the former being dominant at low ambient pressure and the latter at higher pressure.
Rotational Isomerism and Crystal Structures of 2-Methyl-2,3,3- trinitrobutane and 2-Methyl-2,3,3-trinitropentane
Authors: Lee Swee Yong , Koh Lip Lin , Lam Yu Lin , Huang Hsing Hua
Published: July 2006

Dielectric data show that in benzene and carbon tetrachloride at 25 °C, 2-methyl-2,3,3-trinitrobutane and 2-methyl-2,3,3-trinitropentane exist as “trans” : gauche rotameric mixtures in the approximate ratios of 68 : 32 and 57 : 43 respectively. These experimental results are compared with those predicted by AMPAC (AM1) calculations. X-Ray structure investigations show that in both compounds, the nitro group at C2 is “gauche” with respect to the two nitro groups at C3 in the solid state.
Solid-State Reaction between Zinc Hydroxide and 8-Quinolinol
Authors: Dubey Bharat Lal , Tiwari Neeta
Published: July 2006

Solid-state reaction between zinc hydroxide and 8-quinolinol [8-HQ] has been studied. Reaction product has been characterized to be Zn(OH)2(8-HQ)2 by elemental analysis, quantitative estimation of zinc, thermal decomposition in air, thermogravimetry in nitrogen atmosphere, powder X-ray diffraction patterns, and IR spectra. Kinetics of reaction has been investigated by capillary method at different temperatures. Energy of activation for the reaction has been found to be 45.27 kJ mol−1.
Viscosities and Activation Energies of Viscous Flow of the 1,2-Ethanediol/N,N-Dimethylformamide Binary Solvent System
Authors: Corradini Fulvio , Marcheselli Luigi , Marchetti Andrea , Tagliazucchi Mara , Tassi Lorenzo , Tosi Giuseppe
Published: July 2006

Densities (ρ) and absolute viscosities (η) of pure 1,2-ethanediol, N,N-dimethylformamide and of their nine mixtures were determined at nineteen temperatures ranging between −10 and +80 °C. The above properties were fitted by empirical equations stating their dependence on temperature and composition of the mixtures. The extrathermodynamic excess functions, such as the excess rheochor [RE] and the excess Gibbs energy of activation of viscous flow ΔGE, have been studied. The trend of [RE] vs. composition of the mixtures shows negative deviations from ideality, indicating extensive molecular interactions between the components of the binary solvent system. Furthermore, activation enthalpies and entropies for viscous flow have been obtained and their variations with composition have also been discussed.
Thiolate-Bridged Binuclear Nickel(II) Complexes with a Mixed-Spin State
Authors: Mikuriya Masahiro , Handa Makoto , Shigematsu Shinji , Funaki Shunji , Adachi Fumiya , Okawa Hisashi
Published: July 2006

Thiolate-bridged binuclear nickel(II) complexes with N,N-bis[2-(2-pyridyl)ethyl]-2-aminoethanethiol (HL), [Ni2(L)2](ClO4)2·1/2H2O and [Ni2(L)2](PF6)2, have been synthesized and characterized by elemental analyses, infrared and electronic spectra, and magnetic susceptibilities (80–300 K). The crystal structure of the perchlorate has been determined by the single-crystal X-ray diffraction method. The [Ni2(L)2]2+ cation has a novel binuclear structure where one of the nickel ions is coordinated by a square-planar N2S2 donor set and the other has a distorted square-pyramidal configuration (N3S2 donor set) with the pendant pyridyl nitrogen at the apex. From the above results, it was concluded that the present complexes are novel mixed-spin state containing a low-spin Ni(II) and a high-spin Ni(II) in the molecule.
Kinetics and Mechanism of the Oxidation of Formate and Malonate with (trans-1,2-Cyclohexanediamine-N,N,N′,N′-tetraacetato)manganate(III) in Aqueous Medium
Authors: Gangopadhyay Sumana , Ali Mahammad , Banerjee Pradyot
Published: July 2006

The kinetics of the reduction of (trans-1,2-cyclohexanediamine-N,N,N′,N′-tetracetato)manganate(III) by formate and malonate have been investigated in the pH regions 3.6–5.25 and 4.5–8.30 respectively at constant ionic strength and temperature. In the oxidation of formate slight initial increase in absorbance was observed, whereas for malonate oxidation no such indication was noted. Both the reactions are overall second-order with first-order on both the oxidant and reductants. A general rate law for the oxidation of formate and malonate can be given as −d[oxidant]/dt = k[oxidant] × [reductant], where k is the electron-transfer rate constant. The reactivity of HCOO− is (3.26 ± 0.16) × 10−5 dm3 mol−1 s−1 (kK′) and that of Hmal− and mal2− are (4.28 ± 0.12) × 10−5 (k1) and (6.05 ± 0.12) × 10−4 (k2) dm3 mol−1 s−1 respectively at 40 °C. A plausible inner-sphere mechanism has been suggested for the formate oxidation, whereas malonate oxidation has been interpreted by an outer-sphere mechanism.
Novel Reduction of Carboxylic Acids and Hydroboration of Olefins by Electrolysis of Sodium Borohydride
Authors: Shundo Ryushi , Matsubara Yoshiharu , Nishiguchi Ikuzo , Hirashima Tsuneaki
Published: July 2006

Electrochemical oxidation of sodium borohydride in diglyme containing aliphatic or aromatic carboxylic acids followed by acid-catalyzed hydrolysis afforded the corresponding primary alcohols in good yields. Furthermore, similar electrochemical oxidation in the presence of a variety of olefins instead of carboxylic acids, followed by treatment with alkaline–hydrogen peroxide, brought about novel electrochemical hydroboration to give the corresponding alcohols regio- and stereoselectively in good yields.
Thermodynamics of Triple-Helix and Double-Helix Formations by Octamers of Deoxyriboadenylic and Deoxyribothymidylic Acids
Authors: Sugimoto Naoki , Shintani Yuki , Tanaka Atsushi , Sasaki Muneo
Published: July 2006

The triple-helix and double-helix formations by octamers of deoxyriboadenylic and deoxyribothymidylic acids, (dA)8 and (dT)8, have been studied energetically and dynamically by UV and CD measurements, a melting analysis, curve-fitting and nearest-neighbor calculations. The UV mixing curves and CD spectra showed that the triple-helix of (dA)8·2(dT)8 mainly existed in 0.05 mol dm−3 MgCl2 buffer at a low temperature range, while the double helix of (dA)8·(dT)8 existed in 1 and 0.1 mol dm−3 NaCl buffers. The thermodynamic parameters for the triplex and duplex formations were obtained with analysis for the UV melting curves. The free-energy changes at 25 °C obtained from the melting temperature vs. oligomer concentration plots in the MgCl2 buffer were −20.7 kJ mol−1 for the triplex formation and −27.3 kJ mol−1 for the duplex formation, respectively, which were consistent with the values obtained from the curve-fitting calculations. The free-energy changes for the duplex formation at 25 °C were −28.5 kJ mol−1 in 1 mol dm−3 NaCl buffer, and −11.6 kJ mol−1 in 0.1 mol dm−3 NaCl bufer, respectively. These values were discussed in comparison with the predicted values by the nearest-neighbor calculation.
On the Mechanism of Organoaluminum-Promoted Claisen Rearrangement of Allylic Vinyl Ethers
Authors: Nonoshita Katsumasa , Maruoka Keiji , Yamamoto Hisashi
Published: July 2006

The organoaluminum-promoted Claisen rearrangement of allylic vinyl ethers has been mechanistically studied by two sets of experiments and the observed Z and E selectivity is best accounted for by two possible chair-like structures with R substituents axial and equatorial, respectively.
The Reaction of a 10-Methylacridinium Salt with Tertiary Amines
Authors: Tamagaki Seizo , Ueno Masanori , Tagaki Waichiro
Published: July 2006

The reaction of 10-methylacridinium perchlorate with a variety of N,N-disubstituted alkylamines or aralkylamines was investigated in the presence or absence of air. In all cases studied, 10-methyl-9,10-dihydroacridine was produced in approximately 50% yield or more. In addition, either 10-methyl-9(10H)-acridinone or 9-(dialkylamino)-10-methylacridinium perchlorate or both were isolated, each yield being greatly dependent on the bulkiness of alkyl groups on the amines. In the blanket of air, significant amounts of aldehyde was detected. The mechanism was discussed.
Mesomorphic Characteristics of Liquid Crystalline Esters p-Methoxyphenyl p-Alkoxycinnamates
Authors: Dave Jayrang S , Dhake K P
Published: July 2006

The newly synthesized homologous series p-methoxyphenyl p-alkoxycinnamates (I) can be compared with the series N-[p-(p-alkoxycinnamoyloxy)benzylidene] p-anisidines (II).1) All the homologues of both the series (I) and (II) from C1 to C18 are mesogens. In series (II) the first five members decompose due to high transitions at about 300 °C. With decrease in length of the molecules of series (I) than that of series (II), the overall transitions also decrease by about 150 °C. The first seven members in series (II) are nematogens; polymesomorphism begins from octyloxy homologue with the commencement of smectic mesophase and continues to be exhibited upto the last i.e. octadecyloxy homologue. In series (I) also the nematic phase is exhibited upto the heptyl derivative; the smectic phase commences from C8-member in the form of monotropic phase thereby exhibiting polymesomorphism upto the C14 homologue. The last two members of series (II) are smectogens. The odd-even effect is missing in series (II) whereas in series (I), it is seen upto the fifth homologue. In both the series, the N-I curves show a falling tendency— a criterion of high melting series. From textures’ point of view both the series have common features, the nematic phase is threaded when it is the only mesophase shown and homeotropic in polymesomorphic region, whereas the smectic mesophase is focal conic fan shaped of smectic-A variety. This series also yields interesting comparison with the series (III)  p-nitrophenyl p-alkoxycinnamates4) and (IV)  p-chlorophenyl p-alkoxycinnamates.5)
Mechanistic Study of Acid-Catalyzed Proton Exchange in Lactams
Authors: Wang Wei-hsien , Cheng Pai-hui , Huang Chiung-yi , Jong Yih-ling
Published: July 2006

The kinetics of acid-catalyzed proton exchange in N-methylacetamide and a series of lactams (5- to 8-membered ring) were studied. Kinetic data were observed by NMR line-broadening and computer simulation methods. The significant retardation in exchange rate constants of valerolactam and 2-azacyclooctanone is attributed to the high barrier of ring inversion in the N-protonation mechanism of lactams. It is concluded that the imidic acid mechanism is dominant in these two lactams. However, for lactams with much lower barrier of ring inversion, the acid-catalyzed proton exchange is via the N-protonation mechanism as predicted by the inductive effect.
Thermal Reactions of Toluene by Use of a Clusius-Dickel Type Thermal Diffusion Column as a Reactor
Authors: Kawakami Shigenobu , Gao Zhiming , Nakada Masahiro , Yamaguchi Tatsuaki
Published: July 2006

Thermal reactions of toluene were investigated in the temperature range from 1290 to 1410 K under atmospheric pressure in a Clusius–Dickel type thermal diffusion column. The main product of the reaction was benzene, the selectivity of which increased with the rise of reaction temperature, reaching over 50% under most of the reaction conditions studied. The reactions of toluene were characterized by two features; the high selectivity of benzene, and a remarkable change in the selectivity of benzene and bibenzyl with the change of toluene conversion. These two features should be attributable to the thermal diffusion and convection, which caused the hydrogen evolved during the reaction to concentrate around the heater, and subjected toluene to hydrogenolysis without adding hydrogen as a reactant. The experimental results with regard to the change in benzene selectivity can be explained qualitatively by the theories developed for the separation column.
Stability of Large Polycyclic Aromatic Hydrocarbons in the Diffuse Interstellar Medium
Authors: Aihara Jun-ichi , Ichikawa Hiroshi
Published: July 2006

Fragmentation patterns of polycyclic aromatic hydrocarbons (PAHs) observed in mass spectra support the view that sufficiently large compact PAHs have a large possibility of surviving long in the diffuse interstellar medium. Multivalent molecular cations of these PAHs are moderately aromatic.
SAXS Curve Shape Analysis of 2-Butoxyethanol Aqueous Solutions
Authors: Hayashi Hisashi , Udagawa Yasuo
Published: July 2006

Small-angle X-ray scattersing (SAXS) of 2-butoxyethanol aqueous solutions was measured over wide concentration and temperature ranges, and analyzed with polynomial expasion by taking up to the 4-th order term into consideration. It was shown that the mixing state was sensitively reflected in the higher order coefficient of the SAXS curve.
CD Spectral Diagnosis of Absolute Configuration of Tetrahedral or Pseudo-Tetrahedral Metal Complexes of Salicylideneiminates
Authors: Sakiyama Hiroshi , Okawa Hisashi , Oguni Nobuki , Katsuki Tsutomu , Irie Ryo
Published: July 2006

Circular dichroism spectra of tetrahedral or pseudo-tetrahedral metal complexes of chiral salycylideneaminates have been examined with respect to the absolute configuration about the metal ion. The CD couplet pattern associated with the azomethine π–π* transition differs from each other between the complexes of bidentate salicylideneaminates (class A) and the complexes of quadridentate salicylideneaminates (class B), but within each class the CD patern is well correlated with the absolute configuration around the central metal.
Kinetics and Mechanism of Anation of cis-[Ru(bpy)2(H2O)2]2+ Ion by 8-Quinolinol in Water-Ethanol Mixtures
Authors: Mallick Debnath , De Gouri Sankar
Published: July 2006

The anation kinetics of the title complex were investigated spectrophotometrically in 10% (v/v) ethanol–water mixtures and the following rate law has been proposed in the pH range 3.65–6.5.

where k1 is the water dissociation rate constant of the substrate complex, k−1 is the aquation and k2 is the ligand capturing rate constant of the five-coordinate intermediate [Ru(bpy)2(H2O)]2+. The activation parameters have been calculated and compared with other substitution reactions. Considering all the results, a dissociative mechanism has been suggested.