bluuebunny/crossref_metadata_2025 huggingface dataset:
Liquid–Liquid Distribution Study of the Dissociation of Perchloric, Nitric, and Picric Acids in Polar Organic Solvents
Authors: Sekine Tatsuya , Yoshikata Tohru , Saitou Takashi
Published: July 2006

The liquid–liquid distribution equilibria of perchioric, nitric, and picric acids between water and 4-methyl-2-pentanone or 4-methyl-2-pentanol have been determined at 298 K by measuring the concentrations of the anions in the two phases by spectrophotometry. The distribution ratio always increased on increase of the acid concentration; this was explained in terms of an increase in the degree of association of the acids in the organic phase. It was concluded from the analysis of the distribution data that the dissociation constant of perchloric acid was the highest and the value of picric acid was higher than that of nitric acid in 4-methyl-2-pentanone. The dissociation constant of picric acid was also higher in 4-methyl-2-pentanol than that of nitric acid; it was similar to that of perchloric acid. The differences of the dissociation constants were larger in 4-methyl-2-pentanone than in 4-methyl-2-pentanol.
Determination of the Rate Constant for the Reaction NH3+O→NH2+OH
Authors: Fujii Nobuyuki , Sato Hisaaki , Fujimoto Shiro , Miyama Hajime
Published: July 2006

The rate constant for the reaction NH3+O→NH2+OH was determined by the comparison of the calculated ammonia consumption rates with those observed in shock tube experiments in the range of 1690–2310 K, for NH3–N2O–Ar mixtures. The rate constant can be represented by the expression k=3.1×1012exp(−25.5 kJ/RT) cm3 mol−1 s−1.
The Tricritical Point in the n-C8H17SO3Na/n-C4H9OH/H2O/n-C14H30 System
Authors: Kunieda Hironobu , Arai Tsutomu
Published: July 2006

The phase behavior of three coexisting liquid phases has been studied in the four-component system of n-C8H17SO3Na/n-C4H9OH/H2O/n-C14H30. With a rise in the temperature, the three-phase region shrinks to a tricritical point at which the three liquid phases become identical.
The Influence of Culture Conditions on the Fibrillation of Cellulose Gel Produced by Acetobacter xylinum
Authors: Kai Akira
Published: July 2006

The influence of the culture conditions, such as the temperature of incubation and the pH of the culture medium, on the fibrillation of cellulose gels produced by Acetobacter xylinum was studied by means of electron microscopy. The incubation temperature did not show any influence on the fibrillation of cellulose gels as long as it was in the range between 10 to 28 °C. However, in the incubation at 5 °C the fibrillation occurred very slowly. When incubation was carried out at 5 °C, the fibril produced by the 5 °C incubation maintained an amorphous state for about 3h, and the microscopic fibrils appeared in the fibril only after incubation for 12h. However, the width of the microscopic fibril was not influenced by the temperature of incubation. The pH of the medium influenced the linear growth rate of a fibril. The rate increased with an increase in the pH, reached the maximum at pH 6.8, and decreased at higher pHs. The fibrillation occurred more rapidly at a constant temperature as the linear growth rate was lowered, but the width of a microscopic fibril was not influenced by the pH of the medium, just as it was not influenced by the temperature.
Nitrogen-14 Magnetic Resonance Studies of the Exchange of Solvent Pyridine on Bis(β-diketonato)bis(pyridine)nickel(II) and -cobalt(II) Complexes
Authors: Ito Seiko , Yano Yoshiko
Published: July 2006

The analysis of linewidth and shift data of the nitrogen-14 magnetic resonance gave the following activation parameters for the exchange reaction of pyridine (py) on CoA2(py)2 (A=acac, tfa, and tta) and Ni(acac)2(py)2 with a pyridine molecule as bulk solvent: ΔH\eweq=41.4, 51.1, 48.3, and 47.2 kJ mol−1, ΔS\eweq=18, 17, 3, and 10 JK−1 mol−1, and k1 (298K)=2.9×106, 5.3×104, 2.9×104, and 1.3×105 s−1. Here acac=acetylacetonate, tfa=trifluoroacetylacetonate and tta=thenoyltrifluoroacetonate. The electron-withdrawing power of substituent groups on the β-diketonate rings was correlated with more favorable activation of the exchange, that is, the stronger electron withdrawal causes less dissociative activation. This explains qualitatively even the negative ΔS\eweq values observed for similar pyridine exchange in the cases of Co(hfa)2(py)2 (hfa=hexafluoroacetylacetonate) and Ni(tta)2(py)2.
Recovery of Heavy Metals with Calcium Silicon Alloy. III. Stoichiometric Discussion on the Reduction of Copper(II) Ions
Authors: Tokunaga Shuzo
Published: July 2006

For the reduction of Cu2+ ions with Ca–Si alloy in aqueous solutions, the following elementary reactions were postulated:

Ca0+Cu2+=Ca2++Cu0, (1)

Ca0+2H2O=Ca2++H2+2OH−, (2)

Si0+2Cu2++3H2O=H2SiO3+2Cu0+4H+, (3)

Si0+3H2O=H2SiO3+2H2. (4)

From these reactions, amounts of SiIV species were estimated by using those of H2 and increments of H+ ions. Total equivalents of the reduction products showed good agreement with those of the oxidation products, indicating the validity of the elementary reactions. The remained problems of the stoichiometric disagreement and the phenomenon of pH decrease indicated in Part II could be solved by using these elementary reactions. At the beginning of the reaction, a small amount of Cu+ ions formed. Decomposition of water occurred subsequently to the Cu2+ reduction. A contribution of Si0 to the reaction became greater than that of Ca0 at higher Cu2+ concentrations than ca. 10 matom dm−3. Thus, it proved that Si0 in the alloy exhibits a great reducing effect.
Synthesis and Stereochemistry of (Diamine)(2,9-dimethyl-4,7-diazadecane-2,9-dithiolato)cobalt(III) Complexes and Their Derivatives
Authors: Yamanari Kazuaki , Takeshita Norimatsu , Shimura Yoichi
Published: July 2006

Several (diamine)(2,9-dimethyl-4,7-diazadecane-2,9-dithiolato)cobalt(III) complexes, [Co(SNNS)(diamine)]+ (diamine=1,2-ethanediamine and (R,R)-1,2-cyclohexanediamine), were prepared and characterized by the visible-UV absorption, circular dichroism(CD), and 13C NMR spectra. The above SNNS quadridentate ligand gave only the cis-β geometrical isomer, which was chromatographically separated into two diastereomers owing to the configurations of chiral nitrogen atoms. All the thiolato and the corresponding sulfinato complexes exhibited two CD bands of opposite signs in the Co(σ*)←S(σ) ligand-to-metal charge transfer band region. The sign pattern was found to be in connection with the absolute configurations of these complexes.
Selective Adsorption of Molybdenum(VI) and/or Vanadium(V) Using Cross-linked Polystyrene Resins with Bis(2-hydroxyethyl)amino, Bis(carboxymethyl)amino, and Bis(phosphonomethyl)amino Groups
Authors: Nishizawa Masato , Yokoyama Toshiro , Kimura Tetsuo , Suzuki Toshishige M
Published: July 2006

Styrene–divinylbenzene copolymers containing –N(CH2CH2OH)2, –N(CH2CO2H)2, and –N(CH2PO(OH)2)2 moieties have been synthesized and applied to the selective adsorption of molybdenum and/or vanadium from aqueous solution. The equilibrium adsorption capacity vs. pH correlation and exchange kinetics of the resins for MoVI and VV have been studied. The resin containing bis(2-hydroxyethyl)amino group is particularly effective for the selective recovery of MoVI and/or VV by column operation due to its high adsorption capacity and faster exchange rate, whereas other resins required much longer time to attain adsorption equilibrium. The bis(2-hydroxyethyl)amino resin was used for the selective recovery of molybdenum from an acid-leaching solution of waste desulfurization catalyst.
Gas Chromatography–Mass Spectrometry of Trimethylsilyl Derivatives of Some Iminodicarboxylic Acids
Authors: Kawashiro Katsuhiro , Morimoto Shiro , Yoshida Hideyuki
Published: July 2006

Trimethylsilylation of eight iminodicarboxylic acids (IDCAs) with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) or N,O-bis(trimethylsilyl)acetamide was studied under various reaction conditions. The IDCAs include iminodiacetic acid (1), 2- and 3-(carboxymethylamino)propionic acids (2 and 3), 2,2′-, 2,3′-, and 3,3′-iminodipropionic acids (4–6), N-methyliminodiacetic acid (7), and nitrilotriacetic acid (8). For 1–6, both bis- and tris(trimethylsilyl) (TMS) derivatives were formed under usual silylating conditions, although the proportion of amounts of the two derivatives varied depending on reaction conditions. This double derivatization was due to the steric hindrance of N-substituent group. However, under mild silylating conditions (BSTFA alone, 120 °C, 30 min), 1–6 yielded only the di-TMS derivatives. Upon electron impact at 20 eV, both the di- and tri-TMS derivatives showed simple spectra with a molecular (M+) ion and M −15 (loss of CH3). The α,α′-IDCAs (1, 2, 4, 7, and 8) are characterized by fragments M −43 (loss of CH3 and CO) and M −117 (loss of COOTMS) (base peak). On the other hand, the β,β′-IDCA (6) is characterized by fragments M −57 (loss of CH3, CH2, and CO) and prominent M −131 (loss of CH2COOTMS). The α,β′-IDCAs (3 and 5) exhibit both the fragments characteristic of α,α′- and β,β′-IDCAs, M −43, M −57, M −117, and M −131. However, base beaks are usually the fragment M −117 and not M −131.
Reactions of Enolates with Vinyl Selenoxides and Vinyl Selenones. One-step Synthesis of Cyclopropylcarbonyl Compounds
Authors: Ando Ryoichi , Sugawara Tomoo , Shimizu Makoto , Kuwajima Isao
Published: July 2006

In the reactions with enolate anions, organoselenium moieties of aryl vinyl selenoxides and selenones have exhibited two important roles, e.g., activation of C=C bonds for conjugate addition reaction and behaviors as excellent leaving groups. Owing to such characteristic features, ketone enolates react with p-chlorophenyl vinyl selenoxide to afford the corresponding cyclopropyl ketones through an initial conjugate addition followed by substitution processes. On the other hand, use of vinyl selenones usually gives much better results with anionic species of active methylene compounds. Vinyl selenones bearing hydroxyl, ketone, and ester groups can also be employed equally well for this type of transformation.
The Electronic Spectrum of Diphenylhexatriyne. The Interaction of Mutually Perpendicular π and π′ Systems
Authors: Kobayashi Michio , Hoshi Toshihiko , Okubo Jun , Hiratsuka Hiroshi , Harazono Toshie , Nakagawa Masazumi , Tanizaki Yoshie
Published: July 2006

The electronic absorption spectrum of diphenylhexatriyne has been divided into two components polarized along the long and the short molecular axes by means of dichroism analysis using the stretched-polymer-film technique; i.e., a reduced polarization spectrum has been obtained. This reduced polarization spectrum can be explained by a modified PPP calculation including the interaction between mutually perpendicular π and π′ systems in the conjugated system. It has been clarified that the relative intensities of the first and second bands of diphenylhexatriyne reflect the magnitude of interaction between mutually perpendicular π and π′ systems, which is quite great. The magnitude of the electron-repulsion integral between π and π′ electrons is estimated to be about 20–30 per cent of that between ordinary π (or π′) electrons.
A Nuclear Magnetic Resonance Study of the Kinetics of Ligand Exchange Reactions in Uranyl Complexes. VI. N,N-Dimethylformamide Exchange in Bis(acetylacetonato) (N,N-dimethylformamide)dioxouranium(VI)
Authors: Ikeda Yasuhisa , Tomiyasu Hiroshi , Fukutomi Hiroshi
Published: July 2006

The exchange reaction of N,N-dimethylformamide(dmf) in [UO2(acac)2dmf](acac=acetylacetonato) has been studied by the NMR line-broadening method in CD3COCD3 and CD2Cl2. In CD3COCD3, the rate of dmf exchange is independent of the free DMF concentration. The rate constants(s−1) at 25 °C and activation parameters ΔH\eweq(kJ mol−1) and ΔS\eweq(JK−1 mol−1) are 1.19×103, 42.0±1.3, and −45.8±5.5, respectively. In CD2Cl2, the exchange rate depends on the free DMF concentration. The exchange rate constant (kex) is expressed by kex=k1+k2[DMF], where k1(25 °C)=1.90×102s−1, ΔH\eweq=32.8±1.7 kJ mol−1, and ΔS\eweq=−92.0±5.9 JK−1 mol−1, and k2 (25 °C)=5.66×103 M−1s−1(1M=1 mol dm−3), ΔH\eweq=37.0±2.1 kJ mol−1, and ΔS\eweq=−49.6±8.8 JK−1 mol−1. The D and I mechanisms are proposed for the dmf exchange in [UO2(acac)2 dmf].
Magnetic Circular Dichroism and Electronic Absorption Spectra of Mixed (Amine)(carboxylato) Complexes with the [Pd(N)n(O)4–n]-type (n=0–4)
Authors: Nakayama Kazuhiko , Komorita Takashi , Shimura Yoichi
Published: July 2006

Mixed-ligand [Pd(N)n(O)4–n]-type complexes constituting a long systematic series (n=0–4) were synthesized. Ammonia, ethylenediamine, rac-propylenediamine, trimethylenediamine, glycinate, β-alaninate, acetate, oxalate, and malonate were employed as ligands. Their magnetic circular dichroism (MCD) and electronic absorption spectra were discussed together with the CD spectra of the corresponding optically active complexes. The results strongly suggest that the dispersion of MCD observed in the spin-allowed d-d region is primarily a composite of B terms. Moreover, the MCD in the charge transfer region was found to be qualitatively additive with respect to contributions by the constituent ligands. From a detailed examination of the spin-allowed d-d absorption bands, it is noted that the substitution of an N,O-ligand for an N,N-ligand largely affects neither the band area nor band width whereas that of an O,O-ligand for an N,O-ligand does.
The X-Ray Fluorescence Spectroscopy of Inorganic Solids. VI. The P Kα Energy of Phosphate Glasses and Crystals
Authors: Maekawa Takashi , Furukawa Masakazu , Yokokawa Toshio
Published: July 2006

The P Kα emission spectra of several phoshorus compounds and phosphate glasses were examined. The P Kα energies decrease with an increase in the basicities of the matrices. The results also suggest that in order to interprete the chemical shift one must take into account the effects due to changes in the short range structure around the phosphorus atom in the PO4 tetrahedron.
Synthesis of Pharmaceutically Important Heteroaromatics from Methyl Phenyl Sulfone
Authors: Yokoyama Masataka , Tsuji Kouichi , Imamoto Tsuneo
Published: July 2006

Some 5-substituted pyrazoles and pyrimethamine were prepared from 3-methylthio-1-phenyl-4-phenylsulfonyl-2-buten-1-one (5a) or (E)-1-p-chlorophenyl-1-cyano-2-methylthio-3-phenylsulfonylpropene (6b) which could be easily synthesized from methyl phenyl sulfone.
Mechanism of Dipeptidyl Carboxypeptidase Activity of Thermolysin
Authors: Fukuda Mitsuhiro , Kunugi Shigeru
Published: July 2006

Steady state and presteady state kinetic analyses were performed for thermolysin-catalyzed hydrolysis of chromophoric tripeptide substrates with free carboxyl terminal. The pH dependence of kcat showed fairly higher pKa (\simeq7) than that of the second-order rate parameter(kcat⁄Km)(\simeq5) and the pH-dependence of Km resembled that of Ki for N-blocked dipeptidyl inhibitor observed before (S. Kunugi et al., Eur. J. Biochem.  124, 157 (1982)). These findings indicated that the reaction with this type of substrate involves a nonproductive binding mode. In a presteady state kinetic study by stopped-flow method, a burst process of 10–20 ms order was observed before the linear steady state at a relatively low pH and temperature. This process showed moderate pH dependence. Considering these experimental results coupled with those accumulated so far on this enzyme, a unified mechanism including a nonproductive binding and an isomerization process in prior to the cleavage of the peptide bond was proposed for the dipeptidyl carboxypeptidase activity of this enzyme.
Formation of Aluminosilicate by Adsorption of Silicic Acid on Aluminium Hydroxide
Authors: Yokoyama Takushi , Nakamura Osamu , Tarutani Toshikazu
Published: July 2006

When monosilicic acid was adsorbed on aluminium hydroxide, allophane-like compound rapidly formed and the monosilicic acid adsorbed was consumed by the formation of the allophane-like compound until the Si/Al mole ratio of the sample reached 0.33–0.39. Above these ratio, the formation of polysilicic acid occured.
Studies of Bitter Peptides from Casein Hydrolyzate. V. Bitterness of the Synthetic N-Terminal Analogs of des-Gly2–BPIa (Arg–Pro–Pro–Phe–Ile–Val)
Authors: Kanehisa Hidenori , Okai Hideo
Published: July 2006

In order to investigate how the basic amino acid residue in the N-terminal contributes to the bitter taste exhibited by BPIa (Arg–Gly–Pro–Pro–Phe–Ile–Val), we synthesized several kinds of N-terminal analogs of des-Gly2–BPIa (Arg–Pro–Pro–Phe–Ile–Val). The basic amino acid residue of BPIa was found to play an important role in its bitter taste.
The Alkylation of 1-Hydroxyanthraquinone with Visible-light Irradiation
Authors: Tajima Masahiro , Inoue Haruo , Hida Mitsuhiko
Published: July 2006

The 2-position of 1-hydroxyanthraquinone was alkylated by the use of tertiary amine or methanol with visible-light irradiation (λ>400 nm).
Kinetic Study of Excited Diatomic Molecules of Krypton and Xenon
Authors: Ito Yoshiro , Arai Shigeyoshi
Published: July 2006

Excited diatomic molecules of krypton and xenon in 13Σu+ states, Kr2* and Xe2*, were produced by irradiating krypton and xenon in the presence of an excess of argon with short electron-beam pulses. The kinetic behaviors of Kr2* and Xe2* (monitored by near-IR absorption spectrophotometry) are explained quantitatively in terms of mechanisms involving three-body association and radiative decay. The rate constants were found to be (6.5±0.8)×10−33 cm6s−1 for Kr*+Kr+Ar→Kr2*+Ar and (1.6±0.3)×10−32 cm6 s−1 for Xe*+Xe+Ar→Xe2*+Ar. The rate constants for the quenching reactions of Kr2* were determined for Xe, H2, O2, N2, CO, and NO.
Photocatalytic Reactions of Azide Ions on Platinized Titanium Dioxide Powders in Solutions
Authors: Nosaka Yoshio , Ishizuka Yutaka , Norimatsu Kohji , Miyama Hajime
Published: July 2006

Ammonia was formed photocatalytically from an aqueous solution of azide ion by using illuminated Pt/TiO2 semiconductor powder. The reaction products, NH3, N2, and small amounts of N2O and NO3−, were detected. Hydrogen, O2 and N2H4 were not formed in the primary reaction products. From these results, together with photoelectrochemical measurements, a mechanism of the ammonia formation from azide ion and water is presented.
The Crystal Structure of 3-(Adenin-9-yl)-N-(2-succinimidyl)propionamide and Hydrogen Bonding Scheme of Anticonvulsant Drugs with Adenine
Authors: Takimoto Midori , Takenaka Akio , Sasada Yoshio
Published: July 2006

3-(Adenin-9-yl)-N-(2-succinimidyl)propionamide has been synthesized as a model for studying the interaction between cyclic ureide and adenine, and its crystal structure examined. The crystals are monoclinic, the space group P21/c, with unit-cell dimensions of a=10.861(1), b=12.766(1), c=9.753(1) Å, β=91.10(1)°, and Z=4. The ureide moiety is hydrogen bonded to adenine with NH···N(1) (2.903(3) Å) and O···HN(6) (2.955(3) Å). A comparison of the hydrogen bonding patterns of the related compounds with adenine suggests that cyclic ureide anticonvulsant drugs possess the capability of interacting with N(1) and N(6) sites of adenine.
Preparation of {N-(2-Aminoethyl)-1,3-propanediamine}(diethylenetriamine)cobalt(III) Complex, and Separation and Optical Resolution of the Isomers
Authors: Ishii Minoru
Published: July 2006

The mixed ligand complex {N-(2-aminoethyl)-1,3-propanediamine}(diethylenetriamine)cobalt(III) was prepared. Of the five possible geometrical isomers, two were isolated by column chromatography; their formation ratio was ca. 6:4. Both isomers were completely resolved by chromatography. Their configurations were assigned to the meridional type on the basis of electronic, infrared, and circular dichroism spectroscopy, and the X-ray analysis data.
Formation of an N,N-Bidentate Chelate, Bis[4-(4-methyl-2-pyridylazo)resorcinol]nickel(II) Perchlorate, in Dioxane
Authors: Kudo Yoshihiro , Yoshida Noboru , Imamura Taira , Fujimoto Masatoshi
Published: July 2006

The formation of a new N,N-bidentate complex of nickel(II) perchlorate with an N,N,O-terdentate ligand, 4-(4-methyl-2-pyridylazo)resorcinol (4-MePAR), was first detected in dioxane spectrophotometrically. The stability of the N,N-bidentate species in dioxane is strongly affected by the presence of a proton acceptor such as water, ethanol, imidazole, and Cl−, which promote the coordination of the ortho phenolic oxygen in the ligand to form the N,N,O-terdentate complex. The new complex was isolated from dioxane solution and identified to be an N,N-bidentate complex salt, [Ni(4-mepar)2](ClO4)2, having two counter ions, ClO4−. A distortedplanar configuration of the complex was suggested on the basis of IR, X-ray photoelectron spectroscopic, and magnetic measurements.
Viscosity of the Quaternary Gaseous Mixture He–N2–O2–CO2
Authors: Boushehri Ali , Rahmansetayesh Shahrbanoo
Published: July 2006

The kinetic theory expressions for multicomponent gas mixtures are used in conjunction with the law of corresponding states formulated by Kestin, Ro and Wakeham to generate the viscosities of the quaternary gaseous mixture He–N2–O2–CO2. The calculated viscosities are compared with direct measurements performed in a capillary flow apparatus.
Chemical Effects on the X-ray K Emission Spectra of Phosphorus in Organic Compounds
Authors: Yasuda Seiji
Published: July 2006

Spectral changes in the P Kα and P Kβ X-ray emission lines of solid organic phosphorus compounds were measured with a two-crystal X-ray spectrometer. The P Kα line shifted to higher energies with an increasing number of oxygen atoms attached directly to a phosphorus atom. Similar shifts were found in the P Kα satellites, which were always 1.5–2.0 times larger than those of the parent Kα line. There was no simple correlation for relating the P Kβ1 shift to the phosphorus form. The P Kβ profiles of organic phosphorus seemed to be characterized by the surrounding atoms or groups. The appearance of the Kβ′ band offered possible evidence for the existence of phosphorus-oxygen bonding in the samples.
Preparation, and Thermal and Electronic Properties of Double Complex Salts and Cyanide-bridged Complexes Containing Cationic Copper(II) Complexes and Hexacyanoferrate(II) Ion
Authors: Suzuki Masatatsu , Uehara Akira
Published: July 2006

Reaction of copper(II) ion with hexacyanoferrate(II) ion, [Fe(CN)6]4−, in an aqueous solution containing such an amine as en (1,2-ethanediamine), tn (1,3-propanediamine), dien (bis(2-aminoethyl)amine), or dpt (bis(3-aminopropyl)amine), gave two types of complexes: Double complex salts, [Cu(en or tn)2]2[Fe(CN)6]·nH2O(n=5–8), and cyanide-bridged complexes, [(Cu(dien or dpt))2(NC)2Fe(CN)4]·4H2O. The infrared spectra of the complexes in the νCN region revealed that the complexes, [(Cu(dien or dpt))2(NC)2Fe(CN)4]·4H2O, contain cyanide bridges, while in [Cu(en or tn)2]2[Fe(CN)6]·nH2O, no cyanide bridge is present. The thermal reactions of the complexes in the solid state were investigated by means of derivatography under dynamic conditions (D conditions). It was found that dehydration from [Cu(en)2Fe(CN)6]·nH2O resulted in formation of cyanide bridge in the apical position of square planer [Cu(en)2]2+. For [(Cu(dien or dpt))2(NC)2Fe(CN)4]·4H2O, dehydration resulted in the formation of additional cyanide bridges. All the complexes showed metal to metal (iron(II) to copper(II)) charge-transfer transitions (MMCT) in the near ultraviolet or visible region. The complexes, [Cu(en or tn)2]2[Fe(CN)6]·nH2O, exhibited the outer sphere iron(II) to copper(II) charge-transfer bands (OSMMCT) in the near ultra-violet region. [(Cu(dien or dpt))2(NC)2Fe(CN)4]·4H2O and the dehydrated complexes prepared by thermal reaction showed the inner-sphere iron(II) to copper(II) charge transfer bands (ISMMCT) in the visible region. A good correlation was observed between the energies of the MMCT and the d-d band maxima of copper(II) ions.
Desulfurization of N,N′-Diarylthioureas by Lead Tetraacetate Oxidation
Authors: Debroy Abhijit , Nandy Mazumdar Sujit , Barua Parag D , Mahajan Mahinder P
Published: July 2006

Lead tetraacetate oxidation of N,N′-diarylthioureas in refluxing dichloromethane and pyridine gave the corresponding N,N′-diarylureas. Sulfur was isolated during each oxidation reaction.
Electrochemical Reduction of Cyclic and Acyclic Sulfates
Authors: Nonaka Tsutomu , Kihara Shuta , Fuchigami Toshio , Baizer Manuel M
Published: July 2006

It was confirmed that cyclic and acyclic sulfates of diols and monoalcohols could be reduced at cathodes in nonaqueous solvents. The reduction products were greatly affected by the molecular structures of the sulfates. The reduction of the cyclic sulfates of 1,2-diols yielded the corresponding alkenes and disulfate dianions of the parent diols in high yields and current efficiencies were based on one-electron reduction. On the other hand, the cyclic sulfates of 1,3- and 1,4-diols were also reduced by one-electron transfer under similar conditions, but the cycloalkanes expected were not formed and the products were cyclic ethers along with acyclic alkane or unsaturated alcohol. The reduction of the cyclic sulfate of hydrated formaldehyde, which is regarded as a 1,1-diol, did not give any identified products except for a small amount of methane. Finally, acyclic dialkyl sulfates were reduced by one-electron transfer to give complicated mixtures consisting of monomeric alkanes and alkenes, dimeric alkanes, ethers, and/or alkyl metals. Based on the results obtained, the mechanism of reduction of sulfates (mainly cyclic sulfates of 1,2-diols) is discussed.
Studies on the Mechanism of Zeolite X Crystallization. II. Effect of Silica Sources of Starting Materials on the Gas-phase Adsorption at Solid Phases
Authors: Hino Ryozi , Aoi Hiroyasu , Toki Kenzi
Published: July 2006

The mechanism of zeolite X crystallization was studied by using two kinds of silica sources, tetraethyl orthosilicate and silica sol. The adsorption of benzene and cyclohexane was subjected to a measurement to clarify the distribution of cation Na+ and the change in the pore structure and surface of solid phases with reaction progress. The relation between specific surface area and reaction time has been revealed by means of adsorption of nitrogen gas, benzene, and cyclohexane as follows: 1) In the early stage of reaction or in the amorphous solid state, N2≈C6H6≈C6H12 for tetraethyl orthosilicate and N2≈C6H6>C6H12 for silica sol; 2) for crystals in the early stage, N2>C6H12>C6H6 for tetraethyl orthosilicate and N2>C6H12≈C6H6 for silica sol; 3) for crystals in a sufficiently developed stage, N2>>C6H12>C6H6 for tetraethyl orthosilicate and N2≈C6H6>C6H12 for silica sol. In the case of silica sol, the crystallization mechanism is based on inhomogeneous nucleation; a number of critical nuclei may be generated but their dimension is small. In the case of tetraethyl orthosilicate critical nuclei are fewer in number and larger in size than in the case of silica sol; the mechanism of crystallization is based on homogeneous nucleation.
Liquid Crystal Materials with Sulfur Atoms Incorporated in the Principal Structure 2. New Liquid Crystal Compounds; 2-Substituted-5-(p-substituted phenyl)-1,3-dithianes
Authors: Haramoto Yuichiro , Akazawa Koji , Kamogawa Hiroyoshi
Published: July 2006

2-Substituted-5-(p-substituted phenyl)-1,3-dithianes (8), new liquid crystals, were synthesized. The mesomorphic properties of these compounds were compared with those of the corresponding 2-(p-substituted phenyl)-5-alkyl-1,3-dithianes (9). The main difference found between these two liquid-crystal compounds was that some of 8 exhibited both monotropic nematic and smectic liquid-crystal phases but 9 exhibited only the monotropic nematic phase. This difference seems to originate in somewhat increased lateral interactions between molecules. Even for the three-ring compounds, many of them exhibited the monotropic liquid-crystal behavior. This should mean that these 1,3-dithiane compounds strongly tend to exhibit the monotropic liquid-crystal behavior.
Cross Diene-transmissive Diels-Alder Cycloaddition Reaction of Bis(silyloxy) Cross-conjugated Trienes
Authors: Tsuge Otohiko , Kanemasa Shuji , Sakoh Hirohiko , Wada Eiji
Published: July 2006

Cross type of diene-transmissive Diels-Alder cycloaddition has been demonstrated by using two bis-silyloxy cross-conjugated trienes. The first cycloaddition stage of cross reaction, which has to be highly selective in the formation of mono-cycloadducts, has been performed by the reactions of an activated triene with cyclic olefins or those of trienes with acyclic olefins.The secod cycloadditions with a variety of dienophiles provide cross types of bis-adducts. The characteristics of these cross reactios are discussed.
Reformatsky Type Reaction with New Aluminium Reagents Containing Al–Sn or Al–Pb Linkage
Authors: Matsubara Seijiro , Tsuboniwa Noriyuki , Morizawa Yoshitomi , Oshima Koichiro , Nozaki Hitosi
Published: July 2006

Treatment of α-bromo carbonyl compounds with the reagent prepared from n-Bu3SnLi and Et2AlCl or from SnCl2 and Et2AlCl affords enolates which react with ketone or aldehyde to give β-hydroxy carbonyl compounds in good to excellent yields. The reactions proceed similarly with the reagents which are generated from R3PbLi (R=Ph, n-Bu) and Et2AlCl. Catalysis by the added Pd(PPh3)4 complex promotes the reduction effectively and improves the yields of the desired adducts. The regio- and stereoselectivities are disclosed.
The Molecular Structure of Trimethylamine-Borane as Studied from Gas Electron Diffraction and Spectroscopic Data
Authors: Iijima Kinya , Adachi Nobuhiro , Shibata Shuzo
Published: July 2006

The molecular structure of trimethylamine–borane (CH3)3N·BH3 has been determined from gas electron-diffraction data with spectroscopic data. The molecular parameter values and their uncertainties are rg(B–H)=1.261±0.006 Å, rg(N–B)=1.656±0.002 Å, rg(C–N)=1.485±0.001 Å, rg(C–H)=1.108±0.002 Å, ∠HBH=112.8±0.4°, and ∠CNC=109.2±0.2°. The potential barrier around the N–B bond has been estimated to be larger than 5 kcal mol−1 (1 cal=4.183 J). The isotope effects on the B–D bond distance and the DBD angle have also been estimated to be −0.006 Å and 0.4°, respectively, in rα0 parameters.
Synthesis and Characterization of Iron(III) Complexes with Unsymmetrical Quadridentate Schiff Bases, and Spin Equilibrium Behavior in Solution
Authors: Matsumoto Naohide , Kimoto Kazuhiro , Ohyoshi Akira , Maeda Yonezo
Published: July 2006

Several iron(III) complexes with planar unsymmetrical quadridentate Schiff bases composed of 1:1:1 condensation products of acetylacetone, ethylenediamine, and each of salicylaldehyde and o-hydroxyacetophenone have been prepared and characterized, where the Schiff bases are abbreviated as [H2salacen] and [H2hapacen], respectively. The effective magnetic moment of [FeCl(hapacen)] increases gradually from 3.46 BM at 80 K to 5.31 BM at 301 K, and was interpreted by a spin-spin interaction model based on a binuclear structure with an antiferromagnetic interaction parameter of J=−10 cm−1 (S1=S2=5⁄2), while the magnetic moment for [FeCl(salacen)] is 5.86 BM at 80 K and 5.96 BM at 302 K, indicating that the complex is a monomeric species of high-spin type. The bis(imidazole)iron(III) complexes [Fe(im)2(salacen)]BPh4·CH3OH and [Fe(im)2(hapacen)]BPh4·2CH3OH showed a striking thermochromic behavior in various organic solvents, changing from dark red to green with decrease of the temperature. The complexes are essentially of low-spin type in solids, where im and BPh4 denote imidazole and tetraphenylborate, respectively. Electronic, 1H NMR (Evans method), and ESR spectra confirmed that the thermochromism is caused by spin-equilibrium between high-spin(S=5⁄2) and low-spin(S=1⁄2) states of iron(III).
Studies of Polystyrene-based Ion Exchange Fiber. II. A Novel Fiber-form Catalyst for Sucrose Inversion and Methyl Acetate Hydrolysis
Authors: Yoshioka Toshio , Shimamura Masaharu
Published: July 2006

To obtain a novel acid-base catalyst of high activity and easy treatment, we have prepared polystyrene-based fibrous ion exchange catalysts which have large surface areas per unit of weight and which can be utilized in various forms. They are excellent in chemical stability and mechanical strength due to their composite structures, reinforced with polypropyrene. The reactions of sucrose inversion and methyl acetate hydrolysis were carried out by using these cation exchange fibers and ordinary cation exchange resins. The fiber has about sixteen times as high a catalytic activity per equivalent acid as the resin in the case of sucrose inversion. The intrinsic rate constant in the fiber phase is evaluated to be 2.4 times larger than that in the resin phase in terms of the solid-catalysis theory considering the catalytic effectiveness factor and the absorption coefficient. On the other hand, the catalytic activity per equivalent acid of the fiber is almost equal to that of the resin in the case of methyl acetate hydrolysis. It is suggested that this different behavior is attributable to the different molecular sizes of the reactants.
Reaction of Allene with Water Catalyzed by Palladium(0) in the Presence of Carbon Dioxide
Authors: Inoue Yoshio , Ohtsuka Yukihiro , Hashimoto Harukichi
Published: July 2006

A novel reaction involving allene and water took place using palladium(0)–triphenylphosphine as a catalyst in the presence of carbon dioxide to yield 3-methyl-2-methylene-3-buten-1-ol, selectively. A related reaction of allene with methanol or ethanol was found to occur without carbon dioxide.
Alkoxylation of Ferrocene by Photolysis of Haloferrocenes in Aqueous Alcohols
Authors: Shibata Katsuyoshi , Saito Yoshiyuki , Matsui Masaki , Takase Yoshimi
Published: July 2006

The UV irradiation of haloferrocenes in aqueous alcohols resulted in an alcoholysis with the formation of the corresponding alkoxyferrocenes accompanied by the formation of ferrocence. The order of the reactivities of haloferrocenes was I>Br>Cl.
Determination of the Vapor Pressures of Lithium Iodide and Potassium Chloride by Molecular Beam Surface Ionization
Authors: Kawano Hiroyuki , Kenp\={o} Tsutomu
Published: July 2006

Combined techniques of molecular beam effusion from a Knudsen cell and of positive surface ionization on a heated polycrystalline rhenium filament were employed to determine the vapor pressures P (in atm) of LiI and KCl as a function of cell temperature T (in K), thereby yielding the equations:

log10P(LiI)=(7.498±0.046)−(9254±30)⁄T for 583–717 K,

log10P(KCl)=(7.210±0.058)−(11135±45)⁄T for 687–877 K.

The present data on the pressure and on both entropy and enthalpy of sublimation are compared with others in literature.
Magnetic Circular Dichroism Studies of Bipyridyls
Authors: Uchimura Hiroyuki , Tajiri Akio , Hatano Masahiro
Published: July 2006

The magnetic circular dichroism (MCD) and UV absorption spectra of 2,2′- and 4,4′-bipyridyl in cyclohexane and sulfuric acid were measured at room temperature. The MCD spectrum of 2,2′-bipyridyl is different from that of 4,4′-bipyridyl, reflecting the difference in molecular symmetry between them. The absorption and MCD spectral profiles of 2,2′-bipyridyl in cyclohexane are different from those of 2,2′-bipyridyl in mineral acids, in this system protonation taking place on the nitrogen atoms to give a mono- or di-cation with low symmetry. On the contrary, the MCD spectra of 4,4′-bipyridyl in cyclohexane and in acidic media at pH 0.98 exhibit a similar spectral profile to each other due to the D2 symmetry being retained in 4,4′-bipyridyl. Theoretical calculations were carried out on the basis of the PPP-SCF-CI method to get a reasonable explanation for the observed MCD spectra. The assignments of the MCD bands of these compounds are given and their dihedral angles are estimated.
Studies of the Metal Complexes of Cyclohexane Derivatives. VIII. Preparation and Properties of Platinum(II) and Cobalt(III) Complexes Containing (1R,2S,3S)- or (1S,2R,3R)-3-Methyl-1,2-cyclohexanediamine
Authors: Saito Reiko , Kidani Yoshinori
Published: July 2006

(1RS,2SR,3SR)-3-Methyl-1,2-cyclohexanediamine (3m-chxn), a methyl derivative of cis-1,2-cyclohexanediamine, was prepared and optically resolved. The absolute configurations of the enantiomers obtained were assigned on the basis of the Cotton effect of the trans-dichlorobis(diamine) complexes, each containing active 3m-chxn. The complexes of the [Pt(NH3)2L]2+, [Pt(en)L]2+, and [CoL3]3+ types (en=1,2-ethanediamine, L=R,S,S- or S,R,R-3m-chxn) were also synthesized and characterized on the basis of their absorption, CD, and 13C NMR spectra. It has been found that the chelate rings adopted by R,S,S- and S,R,R-3m-chxn predominantly take the δ and λ conformations respectively, because of the preferred equatorial orientation of the C2–C3 bond of the cyclohexane ring. The four diastereomers of [Co(R,S,S-3m-chxn)3]3+ were chromatographically isolated and assigned to fac-Λ(lel3), mer-Λ(lel3), fac-Δ(ob3), and mer-Δ(ob3).
Effects and Role of the Substituents upon 2-Pyridone-catalyzed Mutarotation of 2,3,4,6-Tetra-O-methyl-d-glucose
Authors: Kuzuya Masayuki , Noguchi Akihiro , Okuda Takachiyo
Published: July 2006

We have studied the catalytic activities of various substituted 2-pyridones on the mutarotation of 2,3,4,6-tetra-O-methyl-d-glucose (TMG). The results in an acetone solution at 37 °C showed that an introduction of the polar substituents into the 5- or 6-position, regardless of the nature of the substituents, retarded the relative rate of the mutarotation as compared to a parent compound, while that of alkyl substituents accelerated such rates. Further striking rate enhancements were observed in 5,6-dimethyl-substituted derivatives. Based on experimental results, we concluded that the 2-pyridones which can act as an effective catalyst are such that the 2-pyridone tautomeric form predominantly exists in solution due to its greater association ability and that the 2-pyridinol tautomeric form is energetically more stable for a lower activation energy of the double-proton transfer process in the 2-pyridone-TMG complex.
Synthetic Studies on the Ochtodane Type Terpenes I. Stereoselective Construction of the Ochtodane Skeleton from Myrcene
Authors: Masaki Yukio , Hashimoto Kinji , Sakuma Kazuhiko , Kaji Kenji
Published: July 2006

The ochtodane skeleton, the Carbon framework of 1,1-dimethyl-3-ethylcyclohexane (1) was constructed highly stereoselectively by the acid-catalyzed (SnCl4 or CF3CO2H) cyclization of the terminally functionalized myrcene derivatives, the benzenesulfenyl chloride adduct (7), the terminal β-hydroxy sulfide (8) derived from 7, and myrcene 6,7-epoxide (10). The stereoselectivity of the 3-exo-double bond in 1 formed concomitantly in the cyclization reaction was found to depend remarkably upon the reaction temperature and the 85–94% of E-stereoselectivity was attained at −78 °C. By the method, the ochtodane derivatives with the sulfur- or oxygen-functional groups on the C(6)-position were obtained. Synthetic applications of the ochtodane type compounds (12) and (19) to the aldehyde component (4) of the pheromone of the male boll weevils and to an ochtodane type terpene (26) isolated from the red alga Octodes crockeri, are reported.
Synthetic Studies on the Ochtodane Type Terpenes II. Synthesis of Pleraplysillin-1
Authors: Masaki Yukio , Hashimoto Kinji , Serizawa Yuzuru , Kaji Kenji
Published: July 2006

A furyl sesquiterpene pleraplysillin-1 (1), which possesses the ochtodane skeleton (2) in the molecule, was synthesized regio- and stereoselectively starting from the ochtodane type monoterpene (5). Two approaches were investigated: One is the route by way of the benzenesulfenyl chloride addition to a sesquiterpene (9) or (13) which involve the whole carbon framework of 1 and the exocyclic E- or Z-double bond, and the other involves the regioselective formation of the endocyclic double bond of the ochtodane synthon (15) utilizing the hydroxylassisted epoxide opening reaction followed by homologation with the 3-furylmethyl moiety. In both of the routes the geometry of the exocyclic double bond of the ochtodane synthon played an important role in the regioselective formation of the endocyclic double bond in 1.
Preparation and ESR Studies of New Stable Tocopheroxyl Model Radicals
Authors: Mukai Kazuo , Takamatsu Kimiko , Ishizu Kazuhiko
Published: July 2006

New tocopherol (vitamin E) model compounds (tocopherol 1; 7-t-butyl-2,2-dimethyl-6-chromanol, tocopherol 2; 7-t-butyl-2,2,5-trimethyl-6-chromanol, and tocopherol 3; 5,7-diisopropyl-2,2-dimethyl-6-chromanol) have been synthesized by condensation of 2-methyl-3-buten-2-ol to the corresponding alkylhydroquinone. Electron spin resonance measurements were performed for the tocopheroxyl radicals obtained from the above tocopherol model compounds by oxidizing the phenol precursors with PbO2 in toluene. The proton hyperfine coupling constants and giso-values were determined. The tocopheroxyl radicals 2 and 3 having large alkyl substituents at both ortho positions (C-5 and C-7) are fairly stable, and the radical stability, as measured by the intensities of the ESR signals, increases in the order tocopheroxyl 1<α-tocopheroxyl model<tocopheroxyl 2<tocopheroxyl 3. The result suggests that the in vitro antioxidant activities of tocopherols 2 and 3 are higher than that of α-tocopherol model.
The Mechanism and Stereochemistry of Asymmetric Transformation via Chiral Oxazolines
Authors: Shibata Saizo , Matsushita Hajime , Kaneko Hajime , Noguchi Masao , Sakurai Takao , Saburi Masahiko , Yoshikawa Sadao
Published: July 2006

The stereoselectivity of asymmetric transformation of 2-substituted alkanoic acids via oxazolines was clarified by measuring the isomeric ratio of 13C-labeled lithio oxazolines by 13C NMR. The mechanism of the process was discussed from substituent effects of the oxazoline ring and solvent effects on the transformation.
Steric and Electronic Effects of Unidentate Tertiary Phosphine Ligands on Chemical and Absorption Spectral Properties of Their Mixed Cobalt(III) Complexes with Acetylacetonate Ions
Authors: Katoh Katsuaki , Sugiura Hirofumi , Kashiwabara Kazuo , Fujita Junnosuke
Published: July 2006

A large number of new unidentate tertiary phosphine–cobalt(III) complexes containing acetylacetonate ions were prepared. The complexes are grouped into four types; (A) cis- and trans-([Co(acac)2(PRnPh3−n)2]+, (B) trans-[Co(acac)2(H2O)(PRnPh3−n)]+, (C) trans-[Co(acac)2(L)(PMe2Ph)n+, and (D) trans-(P,P)-[Co(acac)(CN)2(PRnPh3−n)2] (acac: acetylacetonate ion, R: CH3(Me), C2H5(Et), n-C3H7(Pr), i-C3H7(Pri), n-C4H9(Bu), i-C4H9(Bui), c-C6H11 (Cy), Ph: C6H5, L: NH3, CH3NH2, C5H5N(py), NCS−). The complexes of type A form cis and trans isomers in a different ratio depending upon the bulkiness and basicity of a phosphine ligand, and the ratios for the complexes with R=Me and Et were examined in some detail. The trans isomers of type A show a strong absorption band in the d-d transition region, which is assumed to involve charge transfer transitions between the cobalt(III) ion and a phosphine ligand, while the cis isomers exhibit the first d-d band split into two components with medium intensity. The complexes of type B show a distinct peak of the first d-d band, the energy shifts of which were discussed in terms of the bulkiness and basicity of phosphine ligands. The complexes of types C and D were prepared to compare the chemical and absorption spectral properties with those of complexes of types A and B.
Solvent Extraction of Copper(II) with 2-(o-Hydroxyphenyl)benzothiazole
Authors: Shimizu Kenji , Furuhashi Akiko
Published: July 2006

Equilibrium and kinetic aspects of the solvent extraction of Cu(II) with 2-(o-hydroxyphenyl)benzothiazole have been carried out using a water–chloroform system. The complex extracted into chloroform was greenish-brown in color and the absorbance at 490.0 nm obeyed Beer’s law up to 2×10−4 mol/dm3. The complex was 1 : 2 (Cu2+ : ligand) type and the over-all stability constant, β2, was 1.3×1017 at an ionic strength of 0.3. The extraction constant, Kex, was 2.5×10−8. The extraction kinetics were first order with Cu(II) ions and the reagent anions. The rate constant for the reaction was found to be 5.0×109 mol−1 min−1.
Five-coordinate Bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)(tertiary phosphine)palladium(II) and -platinum(II) Complexes. X-Ray Crystal and Molecular Structures and Fluxional Motions in Solution
Authors: Okeya Seichi , Miyamoto Toshiko , Ooi Shun’ichiro , Nakamura Yukio , Kawaguchi Shinichi
Published: July 2006

Five-coordinate complexes [M(hfac)2L] (M=Pd, Pt; hfac=1,1,1,5,5,5-hexafluoro-2,4-pentanedionate anion) were produced by the reactions of [M(hfac)2] with equimolar amounts of tertiary phosphines, phosphites, and triphenylarsine. They were characterized by 1H, 13C, 19F, and 31P NMR spectra in solution and several complexes containing bulky phosphines as L were isolated, and structures of [Pd(hfac)2{P(o-tolyl)3}] and [Pt(hfac)2{P(cyclohexyl)3}] were determined by X-ray analysis. Both complexes have very distorted square-pyramidal structures, one of the two hfac anions in either of them spanning the apical and basal coordination sites. NMR spectra at various temperatures disclosed the fluxional behaviors of these complexes which retain the solid-state structures at such low temperatures as −60 °C. Two kinds of twist mechanisms were proposed.
Cyclodienones. X. Reaction of Halo-cyclohexadien-1-ones with Phenols in the Presence of α-Picoline and Preparation of 4-Hydroxy- and 2-Hydroxyphenyl Aryl Ethers
Authors: Tashiro Masashi , Itoh Takashi , Fukata Gouki
Published: July 2006

Reaction of 4-halocyclohexadienones such as 4-bromo-(1a), 4-chloro-2,4,6-tri-t-butyl-(1b), 2,4-dichloro-4,6-di-t-butyl-2,5-cyclohexadien-1-one, and 2,4-dichloro-2,6-di-t-butyl-3,5-cyclohexadien-1-one with phenols in the presence of α-picoline was carried out under various conditions. The reaction of 1a and 1b with phenols afforded the corresponding 2-aryloxy-4,6-di-t-butyl phenols together with various by-products. The AlCl3-catalyzed trans-t-butylation of 2-aroxy-4,6-di-t-butyl-phenols, which were obtained by the above reaction, afforded the corresponding 2-hydroxyphenyl aryl ethers. The similar reaction of 4-aroxy-2,4,6-tri-t-butyl-2,5-cyclohexadien-1-ones also afforded the corresponding 4-hydroxyphenyl aryl ethers.
Ylide–Metal Complexes. VIII. The Preparation and Properties of Metal (Cu, Ag, Au, Zn, Cd, Hg, Ge, Sn, Pb, Pd, and Pt) Complexes with Methylenetris(dimethylamino)phosphorane
Authors: Yamamoto Yoshihisa
Published: July 2006

Bis[methylenetris(dimethylamino)phosphorane]metal chlorides,[(Me2N)3PCH2–M–CH2P(NMe2)3]Cln(M: Cu, Ag, Au, Zn, Cd, Hg; n: 1 or 2), have been isolated from a reaction mixture of methylenetris(dimethylamino)phosphorane (Me2N)3P=CH2 (L) and CuCl, AgCl, (C6H5)3PAuCl, ZnCl2, CdCl2, or HgCl2 in the mole ratio of 2:1 or 3:1. The reactions of L with R3MCl (M: Sn, Pb; R: Me, C6H5) in the mole ratio 1:1 yield new monomeric compounds of [methylenetris(dimethylamino)phosphorane]trimethyl(or triphenyl)metal chloride, [(Me2N)3PCH2–MR3]Cl. The reactions of L with PdCl2 or PtI4 in the mole ratio of 2:1 or 4:1 yield [(Me2N)3PCH2]2PdCl2 and [(Me2N)3PCH2]4PtI4, respectively. The Ag, Au, Sn, and Pb complexes are stable. Their properties are compared with those of the metal complexes with methylenetriphenylphosphorane, (C6H5)3P=CH2.
Aliphatic Claisen Rearrangement Promoted by Organoaluminium Reagents
Authors: Takai Kazuhiko , Mori Ichiro , Oshima Koichiro , Nozaki Hitosi
Published: July 2006

Organoaluminium compounds, R3Al, promote the Claisen rearrangement of allyl vinyl ether derivatives at room temperature under transfer of R or H as a nucleophile to the aldehydic carbon. Treatment of 1-butyl-2-propenyl vinyl ether with a hexane solution of Me3Al (1.0 M, 2.2 equiv) in CH2ClCH2Cl at 25 °C afforded 5-decen-2-ol (91% yield, E⁄Z=47⁄53), which was produced by the [3,3] sigmatropic rearrangement and successive methylation. The rearrangements with alkynylation, alkenylation, and hydrogenation are also achieved. The regular Claisen rearrangement products, or γ,δ-unsaturated aldehydes (ketones), are obtained at 25 °C in good to excellent yields with Et2AlSPh (2.5 equiv) or the combination of Et2AlCl (2.0 equiv) and PPh3 (2.2 equiv).