bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduction of Ketones and Aldehydes via Catalytic Hydrosilylation Using Triethoxysilane and Trimethoxysilane
Authors: Matsumoto Hideyuki , Hoshino Yoshikazu , Nagai Yoichiro
Published: July 2006

It was found that ketones and aldehydes can be effectively reduced via catalytic hydrosilylation using triethoxysilane and trimethoxysilane in the presence of RhCl(PPh3)3 or RuCl2(PPh3)3, followed by ethanolysis or methanolysis.
An MO Study of the Reaction Mechanism of Photoisomerization from Isoxazole via Azirine Intermediate to Oxazole
Authors: Tanaka Hidetsugu , Osamura Yoshihiro , Matsushita Toshio , Nishimoto Kichisuke
Published: July 2006

The reaction mechanism of photoisomerization of isoxazoles and the wavelength dependent photochemistry of azirine intermediates which are the photoisomerization reaction intermediates are investigated theoretically by means of ab initio MO-CI calculation. The present calculation shows that the lowest excited singlet state, S1, of azirine intermediate is an (n→π*) state localized at the carbonyl chromophore, while the S2 state is assigned to be an (n→π*) state localized at the ketimine chromophore. Intersystem crossing from S1 to T1 states of azirine intermediate causes the N-C bond rupture of azirine ring and leads to isoxazole. On the other hand, azirine intermediate in the S2 state proceeds to the C-C bond break of azirine ring and converts to oxazole via intersystem crossing to the T1 state.
Synthetic Inorganic Ion-exchange Materials. XXXI. Ion-exchange Behavior of Tervalent Metals and Rare Earth Elements on Crystalline Antimonic(V) Acid Cation Exchanger
Authors: Abe Mitsuo , Tsuji Masamichi , Kimura Masato
Published: July 2006

The increasing order of ion-exchange selectivity for tervalent metal ions: Al3+<<Ga3+≤Yb3+<Fe3+<La3+<In3+, was established in 1 mol dm−3 nitric acid solution on a crystalline antimonic(V) acid (C-SbA) cation exchanger. Strong correlation was found between the selectivity and the effective ionic radii of these ions. Large separation factors for neighboring ions were obtained, as compared with the commercial ion exchange resin. An effective separation of aluminium(III)-iron(III) ion pairs and a group separation of garium(III) and ytterbium(III) ions from lanthanum(III) ion were performed by using a relatively small C-SbA column (4 cm× 0.4 cm i.d.).
A Sandwich Photocell Using Chlorophyll Electrodes
Authors: Takahashi Fujio , Komori Tetuo
Published: July 2006

A sandwich-type photocell was made by placing an electrolyte between two electrodes. A transparent electrode, a glass plate coated with In2O3, was used for one electrode. A mixture of chlorophyll and 2-(cis-10-heptadecenyl)-6-methoxy-p-benzoquinone was spread onto this transparent electrode. A Pt plate covered by chlorophyll or a mixture of chlorophyll and riboflavin tetrabutyrate was used as the other electrode. The electrolyte contained flavin mononucleotide in a phosphate buffer. The potential difference between the two electrodes was 314 mV and the maximum photovoltage under illumination was 176 mV. The photocell is compact and can produce a photocurrent for more than 90 h.
Heterogeneous Reactions of Nitrogen Monoxide on Titanium Dioxide Photocatalysts in Solutions
Authors: Yoneyama Hiroshi , Shiota Hisashi , Tamura Hideo
Published: July 2006

Heterogeneous reactions of nitrogen monoxide on illuminated TiO2 catalysts in 1 mol dm−3 HClO4 were studied by electrochemical analysis. Nitrogen monoxide was reduced to ammonia and hydrazine. The main reaction was found to be a chemical reaction of hydroxylamine as a reaction intermediate with nitrogen monoxide to give molecular nitrogen. Nitrate was detected as an oxidation product formed by the counterpart reaction of the reduction of nitrogen monoxide.
Crystal and Molecular Structure of Antibiotic Gilvocarcin M
Authors: Hirayama Noriaki , Takahashi Keiichi , Shirahata Kunikatsu , Ohashi Yuji , Sasada Yoshio
Published: July 2006

The structure of gilvocarcin M, C26H26O9, an antibiotic with a novel carbon skeleton, has been determined by single crystal X-ray analysis. The space group is P21 with a=15.063(5), b=16.162(4), c=4.905(2) Å, β=91.47(3)°, and Z=2. The structure was solved by direct methods, and least-squares refinement using 1734 reflexions gave the final R value of 0.054. The title compound is composed of a unique aglycone and a fucofuranose, which are linked together through a C–C glycosyl linkage. The furanose ring takes the °E conformation.
Formation of Zn-bearing Ferrite by Air Oxidation of Aqueous Suspension
Authors: Kanzaki Tadao , Nakajima Jun-ichiro , Tamaura Yutaka , Katsura Takashi
Published: July 2006

Zn-bearing spinel ferrites were obtained by air oxidation of the iron(II) hydroxide suspension of the mole fraction Zn(II) to [Zn(II)+Fetotal], rZn, ranging from 0.029 to 0.33 (except for 0.057) at pH 10.0 and 65 °C, but at rzn=0.057 only α-FeOOH was formed. The Zn-bearing spinel ferrite obtained at rZn=0.33 has the normal spinel structure. At pH 8.0, the Zn-bearing spinel ferrite is obtained at rZn=0.057, but the spinel ferrite is slightly oxidized to γ-Fe2O3.
Selective Oxidation of Unsymmetrical Thiosulfinic S-Esters to the Corresponding Thiosulfonic S-Esters with NaIO4
Authors: Takata Toshikazu , Kim Yong Hae , Oae Shigeru
Published: July 2006

Unsymmetrical thiosulfinic S-esters were oxidized with sodium metaperiodate in aqueous media to the corresponding unsymmetrical thiosulfonic S-esters nearly quantitatively. The oxidation was accelerated by addition of a catalytic amount of inorganic and organic acids or halogen. Sulfinic esters were produced competitively along with the thiosulfonic S-esters in the oxidation of thiosulfinic S-esters in aqueous alcohol. However, unsymmetrical disulfides were not oxidized selectively to the corresponding unsymmetrical thiosulfonic S-esters but a mixture of both symmetrical and unsymmetrical thiosulfonic testers was obtained.
Synthesis and Properties of Bridgehead-substituted Bicyclo[n.2.2] Bridgehead Alkenes
Authors: Sakai Yasuo , Toyotani Shingo , Ohtani Masaru , Matsumoto Masaharu , Tobe Yoshito , Odaira Yoshinobu
Published: July 2006

The bridgehead-substituted bicyclo[n.2.2] bridgehead alkenes (1b–3b) (1, n=4; 2, n=5; 3, n=6; b, R=OAc) were synthesized based on the oxidative decarboxylation of [n.2.2]propellanecarboxylic acids with lead tetraacetate. The parent alkene (1a–3a) (a, R=H) and other bridgehead-substituted derivatives (1c–3c and 1d–3d) (c, R=OH; d, R=Cl) were prepared from 1b–3b. The examination of the 13C NMR chemical shifts of 1a–c, 2a–c, and 3a–c indicates the presence of electronic interaction between the bridgehead double bond (Cγ) and the opposite bridgehead carbon (Cα), being the homoallylic position of the double bond. From the product study and the kinetic results of the solvolysis of the bridgehead chlorides 1d–3d, it is indicated that the homoallylic participation of the strained bridgehead double bond to the carbonium ion center located at the opposite bridgehead position operates in the solvolysis of 1d and 2d. It may be, therefore, concluded that highly strained bridgehead alkenes, especially, bicyclo[4.2.2]decene system, show remarkable homoallylic type α, γ-interaction both in the ground state and in the transition state (carbonium ion).
Chemistry of Dienyl Anions. IV. Geometry of Pentadienyl Anions in Solution and in the Solid State Determined by Regioselective Trimethylsilylation and NMR
Authors: Yasuda Hajime , Yamauchi Michihide , Ohnuma Yasuo , Nakamura Akira
Published: July 2006

The configurational analysis of a series of alkyl substituted pentadienyl anions in THF was examined by trimethylsilylation and from the variable temperature 1H- and 13C-NMR spectra. Potassium pentadienide, -2-methylpentadienide or -2,4-dimethylpentadienide produced preferentially (Z)-2,4-pentadienyltrimethylsilane or its methyl substituted analogues to indicate that these compounds have the “U”-shaped structure in solution. By contrast, trimethylsilylation of potassium pentadienide and -2-methylpentadienide in the crystalline state produced the (E)- and the (E),(Z)-isomers, respectively, suggesting that the geometry is drastically changed to the “W”- or “S”-shaped by the medium effect. The W-shaped structure of potassium 3-methylpentadienide in THF and in the solid state is exceptional. Geometry of trapped products of potassium cycloheptadienide and -cyclooctadienide is also (Z) but the silylation occurred on the central carbon in contrast to the terminal silylation seen for the open-chain pentadienides. Geometry of these dienyl anions determined by NMR below −30 °C was consistent with the result obtained from trimethylsilylation. Superficial conflict between MINDO/3 prediction and the experimental evidence was reasonably reconciled by considering contact ion pairs for potassium pentadienide in THF and more strongly-solvated ion pairs for the lithium analogues.
The Use of Grignard Reagents in the Synthesis of Carbohydrates. III. The One-way Anomerization of Methyl Glycofuranosides and the Opening of Their Furanose Rings
Authors: Kawana Masajiro , Kuzuhara Hiroyoshi , Emoto Sakae
Published: July 2006

The anomerization of methyl glycofuranoside derivatives with methylmagnesium iodide or t-butylmagnesium bromide occurred in a one-way manner. For example, methyl 5-O-benzyl-β-d-ribofuranoside (3β) was converted into the corresponding α-anomer (3α) in a 95% yield when a mixture of 3β and t-butylmagnesium bromide in benzene–ether was heated at about 75 °C to remove the ether; the reverse reaction (from 3α to (3β) did not proceed. The reaction of 3β with methylmagnesium iodide gave open-chain products (33%), besides 3α (30%). Twenty kinds of anomers were tested, and the mechanisms of the reactions were discussed. The cleavage of a benzyl- or trityl-protecting group with the Grignard reagent was also observed during the reaction.
Structural Study of Optical Resolution. IX. The Crystal Structure of (−)589-Tris(biguanide)cobalt(III) Chloride d-Tartrate Pentahydrate
Authors: Tada Toshiji , Kushi Yoshihiko , Yoneda Hayami
Published: July 2006

The crystal structure of the less-soluble diastereomeric salt, (−)589-[Co(Hbg)3]Cl(d-tart)·5H2O, has been determined by X-ray analysis (R=0.056, 1277 reflections). The crystals are orthorhombic, with the space group of C222, Z=4, a=24.846(5), b=12.970(2), and c=8.645(2) Å. The main features of the crystal structure are as follows: (1) The complex cation and Cl− anion are arranged alternately along the b-axis to form an infinite spiral chain. The distances between N(Hbg) and Cl are 3.452 and 3.376 Å. (2) The tartrate ions exist as a dimeric unit whose structure closely resembles that of [Sb2(d-tart)2]2−. Through the center of this dimeric unit pass three mutually orthogonal twofold axes. (3) There are short contacts between the Hbg ligands and the tartrate ions along the twofold axis of the complex; N(A2)···OT3 2.862, N(B2)···OT2 3.116, N(B3)···OT2 2.754, and N(B4)···OT1 2.963 Å. On the basis of these features, the chiral discrimination mechanism is discussed.
Thermal Rearrangement of N-(Substituted allyl)-1-naphthylamines
Authors: Inada Seisaku , Kurata Ryu-ichiro
Published: July 2006

The title reaction was examined and the results were compared with those of the thermal reaction of the corresponding N-tosyl derivatives.
Transmission of Low-energy Electrons through Thin-films of Benzene and Hexane at 80 K
Authors: Hiraoka Kenzo , Nara Masaji
Published: July 2006

Transmission spectra of low-energy electrons (0–15 eV) for 10–100 Å films of benzene and hexane have been measured at 80 K. Resonances are clearly indicated by electron current It transmitted through the dielectric as a function of the incident electron energy Vi displayed as dIt⁄dVi  vs.  Vt. When the film thickness of hexane was increased, the height of the first peak (due to injection of electrons in the film) decreased drastically and a second peak appeared and grew strongly. From the energy of the second peak, the bulk electron affinity (–V0) of thin film was estimated. The V0 values for hexane and octane are 0.9 and 1.0 eV, respectively.
The Crystal and Molecular Structure of Grayanotoxin XIX. A New Minor Diterpene from Leucothoe Grayana Max.
Authors: Furusaki Akio , Gasa Shinsei , Ikeda Ry\={u}z\={o} , Matsumoto Takeshi , Yasuoka Noritake , Matsuura Yoshiki
Published: July 2006

The molecular structure of grayanotoxin XIX, C20H30O3, has been determined by means of X-ray crystal analysis. The crystals are triclinic, with two molecules in a unit cell with dimensions of a=10.406, b=10.648, c=8.003 Å, α=90.00, β=94.25, and γ=102.76°; the space group is P1. 2671 unique intensity data were collected on a four-circle diffractometer with Ni-filtered Cu Kα radiation. The structure was elucidated by the Monte Carlo direct method, using the 50 strongest reflections as the starting set. The block-diagonal least-squares refinement reduced the R value to 0.038. The structure obtained corresponds to 14-deoxygrayanotoxin VII. The two independent molecules exist in different conformations: one has a half-chair A-ring, and the other, an envelope A-ring. In both molecules, the B-ring takes a conformation intermediate between the chair and twist-chair forms, and the C-ring adopts a boat conformation. The crystal consists of infinite hydrogen-bonded molecular chains along the c axis.
Brillouin Scattering Study of Clathrate Hydrate Formation in Acetone–Water Solution
Authors: Kato Tadashi , Yudasaka Masako , Fujiyama Tsunetake
Published: July 2006

Light scattering spectra have been observed for binary solutions of acetone and water at 24, 34, and 44 °C in the concentration range of 0≤xAC≤0.25, where xAC is the mole fraction of acetone. The hypersonic velocities and the adiabatic compressibilities at 4.5 GHz were obtained from the observed values of Brillouin shifts. The observed concentration and temperature dependencies of the adiabatic compressibility were interpreted by assuming the existence of clathrate hydrate-like local structures in the solutions. The adiabatic compressibilities for binary solutions of t-butyl alcohol (TBA) and water were used as reference data. A comparison is made between the local structure formed in the acetone–water solution and that in the TBA–water solution.
Temperature Dependence of Thermal Positive Ion Production through Dissociation of Polyatomic Molecules
Authors: Kawano Hiroyuki , Hidaka Yoshiaki , Suga Masao
Published: July 2006

The production of a thermal positive ion (M+) from a polyatomic molecule (MX) incident upon a heated metal surface is investigated theoretically as a function of surface temperature (T). The quantitative expression of the ion emission current (i+) of M+ at a constant incident flux (N) of MX is found to change according to the condition whether the work function (φ) of the surface is higher or lower than the first ionization energy (I) of M and also to the degree of dissociation (γ) of MX on the surface. Namely,

(Remark: Graphics omitted.)

Here D is the bond dissociation energy of MX and K′s are virtually independent of T. In any other cases i+ cannot be expressed in such a simple form. The particular temperature regions corresponding to γ≈1 or γ<<1 are evaluated for given sets of N, D, I, and φ.
Electrochemical Fixation of Molecular Nitrogen on p-Type Gallium Phosphide Photocathode
Authors: Koizumi Masashi , Yoneyama Hiroshi , Tamura Hideo
Published: July 2006

Electrochemical fixation of molecular nitrogen to ammonia and hydrazine at p-type GaP photocathodes was studied in nonaqueous electrolytes containing either one of titanium tetraisopropoxide, titanium trichloride, vanadium trichloride, or chromium trichloride and a trace amount of water. Positive evidences for the nitrogen fixation were obtained in these electrolytes, but the current efficiency was quite low, and usually less than 1%. It is suggested from the present study that there are a variety of choices of electrolyte systems for the nitrogen fixation.
The σ-Bonded Palladium(II) Complexes of 2-Aryl-4,4-dimethyl-2-oxazolines
Authors: Izumi Takeo , Watabe Hiroyuki , Kasahara Akira
Published: July 2006

Reactions of 2-phenyl-4,4-dimethyl-2-oxazoline with lithium tetrachloropalladate(II) and palladium(II) acetate give dichlorobis(2-phenyl-4,4-dimethyl-2-oxazoline,3-N)palladium(II) and a cyclopalladated binuclear complex, di-μ-acetato-bis[2-(4′,4′-dimethyl-2′-oxazolinyl)phenyl,1-C,3′-N)dipalladium(II), respectively. The latter complex is readily converted by a metathetical reaction with lithium chloride into its chloro-bridged analogue. The chloro-bridged complex reacts with triphenylphosphine to give the corresponding mononuclear σ-bonding palladium complex. All the complexes prepared in this study were characterized by means of IR and NMR spectroscopies.
Electron-transfer Reaction from Sodium Benzenethiolate to Acceptors Assisted by Photo-excited Tris(2,2′-bipyridine)ruthenium(II)
Authors: Miyashita Tokuji , Matsuda Minoru
Published: July 2006

The photo-excited tris(2,2′-bipyridine)ruthenium(II) (Ru(bpy)32+*) was effectively quenched by sodium benzenethiolate in acetonitrile (Stern-Volmer constant=4860 dm3 mol−1). The flash photolysis of a solution containing Ru(bpy)32+ and benzenethiolate (excitation wavelength (λ)>480 nm) produced transient species absorbing ca. 510 nm; this species was identified as Ru(bpy)3+ and decayed with first-order kinetics with k=3.0 s−1. This slow decay of Ru(bpy)3+ implies that the back-electron-transfer reaction was suppressed. The decay of Ru(bpy)3+ was accelerated by the addition of water, suggesting the possibility of the reaction between Ru(bpy)3+ and water, though no H2 was detected. The steady irradiation of a solution containing Ru(bpy)32+, benzenethiolate, and an electron-acceptor produced the radical anion of the added acceptor, which was detected with ESR spectroscopy.
Conformational Change of Poly(l-lysine) by Sodium Octyl Sulfate as Studied by Stopped-flow Circular Dichroism Method
Authors: Takeda Kunio , Iba Akira , Shirahama Keishiro
Published: July 2006

Circular dichroism (CD) studies were made on the conformational changes of poly(l-lysine) (PLL) induced by sodium octyl sulfate (SOS). The conformation of PLL has a negative double maximum characterizing the α-helix in 4.0–6.0×10−3 mol/dm3 SOS solutions. At a higher concentration of SOS, PLL takes the β-structure, the random coil remaining below it. These conformational changes were followed by measuring ellipticities at 192, 207, and 221 nm according to a CD stopped-flow method. The rate constant was ca. 2.7×10−1 s−1 for the coil-helix transition, the transition rate from coil to β-structure being high depending on SOS concentration. The β-structure was attained by adding a small amount of 1-octanol to the α-helical PLL in 5.0×10−3 mol/dm3 SOS. The effect of the surfactant on the triphasic conformation changes is discussed in terms of hydrophobic environment.
The Isolation, Characterization, and Isomerization of cis- and trans-Bis(benzonitrile)dichloroplatinum(II)
Authors: Uchiyama Toshihiko , Toshiyasu Yoshio , Nakamura Yukio , Miwa Toshio , Kawaguchi Shinichi
Published: July 2006

The reaction of platinum(II) chloride with neat benzonitrile gave bis(benzonitrile)dichloroplatinum(II) as a mixture of cis and trans isomers in variable proportions, depending on the temperature. The geometry of the chromatographically separated isomers was identified on the basis of the dipole-moment and IR data. The 13C NMR spectra in CDCl3 also enabled us to discriminate between isomers in both chemical shift and coupling to the 195Pt of the cyanide carbon, the resonance peak of which was utilized to follow the isomerization. The rate constant (kc) for the cis-to-trans isomerization was found to be (3.8±0.3)×10−6 s−1 in CDCl3 at 25 °C, ten times larger than that [kt=(2.9±0.2)×10−7 s−1] of the reverse reaction. The equilibrium between cis and trans strongly favored trans in CDCl3 at 25 °C, whereas in benzonitrile the cis form was the dominant species at room temperature, while the trans form was dominant at higher temperatures.
13C NMR Spectra of Series of Bis(2,2′-bipyridine)cobalt(III) and Bis(1,10-phenanthroline)cobalt(III) Complexes
Authors: Utsuno Shunji , Yoshikawa Yuzo , Tatehata Akira , Yamatera Hideo
Published: July 2006

Twenty-eight cobalt(III) complexes of these types: [Co(LL)3]3+ and [CoXX(LL)2]n+ (LL=2,2′-bipyridine or 1,10-phenanthroline, and XX=2CN−, 2NO2−, ethylenediamine, 2NH3, glycinate ion, 2H2O, C2O42−, CO32−, 2SCN−, 2N3−, 2CH3COO−, 2Cl−, or 2Br−, were prepared, and their 13C NMR spectra were recorded. Most of the resonances in the complexes were assigned mainly by the technique of selective proton decoupling. In the bpy complexes, the chemical-shift difference between corresponding carbon atoms was the greatest in the C-6 and C-6′ pair. The phen complexes also gave parallel results. The main factor responsible for the chemical-shift differences of the C-6 and C-6′ pair is explained as resulting from the difference in σ-bonding ability between the pyridyl group and the ligand, X.
Synthetic Approach toward Antibiotic Tunicamycins
Authors: Fukuda Yoshimasa , Sasai Hiroaki , Suami Tetsuo
Published: July 2006

Higher-carbon carbohydrates, undecose, and dodecose derivatives have been synthesized by base-catalyzed addition between nitro sugar and sugar aldehydes. The addition reaction of 3,5-O-benzylidene-6,7-dideoxy-1,2-O-isopropylidene-7-nitro-α-d-gluco-heptofuranose (3) with 2,3 : 4,5-di-O-isopropylidene-d-arabinose yielded two isomeric dodecose derivatives. The analogous addition of 3 with 2,4-O-ethylidene-d-erythrose afforded an undecose derivative.
Mechanisms of Thermal Decomposition of trans- and cis-Dialkylbis(tertiary phosphine)palladium(II). Reductive Elimination and trans to cis Isomerization
Authors: Ozawa Fumiyuki , Ito Takashi , Nakamura Yoshiyuki , Yamamoto Akio
Published: July 2006

Series of trans- and cis-dialkylpalladium(II) complexes having tertiary phosphine ligands (L) of various basicities and bulkiness have been prepared and their thermolysis and isomerization mechanisms in solution have been studied. Examination of the cause of selective formation of cis-dialkyl isomers by using alkyllithium revealed a new type of trans to cis isomerization promoted by the alkyllithium. A process involving the formation of a trialkyl-palladate intermediate is proposed as a mechanism for the trans to cis isomerization. Evidence to support the mechanism has been obtained by experiments using LiCD3. Thermolysis of cis-PdR2L2 has been demonstrated to proceed through a unimolecular process initiated by a rate-determining dissociation of L to produce a three-coordinate “cis-PdR2L” which reductively eliminates the R groups. Addition of free ligand to the system containing cis-PdMe2L2 effectively blocks the reductive elimination pathway thus forcing the complex to be thermolyzed by a route involving liberation of methane. The second, novel type of trans to cis isomerization reaction proceeding via an intermolecular methyl transfer process has been discovered. As the crucial intermediate in the process a methyl-bridged complex formed between the partly dissociated three-coordinate species and undissociated complex has been postulated. Thermolysis of trans-PdMe2L2 has been found to proceed via initial isomerization to the cis form followed by reductive elimination. The trans-cis isomerization equilibrium greatly favors the cis form for complexes having phenyl-substituted phosphines. For the PEt3-coordinated palladium dimethyl, however, an equilibrium trans/cis ratio of 1.2 is reached at 39 °C. Factors influencing the stability of the palladium alkyls having the tertiary phosphine ligand are discussed on the basis of the present results as well as comparison of the thermolysis behavior of trans-PdEt2L2 and other transition metal alkyls. The presence of an energy barrier between the dissociated T-shaped intermediates trans-PdMe2L and cis-PdMe2L has been assumed. A unimolecular reductive elimination pathway proceeding from the T-shaped cis-PdMe2L intermediate through a Y-shaped transition state consistently accounts for the thermolysis as well as isomerization behavior of the trans-and cis-PdMe2L2.
A Reinvestigation of the Crystal and Molecular Structure of the β-Form of 2,4,6-Trimethyl-1,3,5-Trithiane
Authors: Sekido Kiyotane , Itoh Jun , Noguchi Teruo , Hirokawa Sakutaro
Published: July 2006

The crystal structure of the title compound has been reinvestgated and refined to a final R factor of 0.057 for 1286 independent reflections. The six-membered ring takes a chair-form. All the three methyl groups are in the equatorial position. The mean values are 1.818 Å and 1.513 Å for the S–C and C–C distances respectively, and 101.3° and 108.5° for the C–S–C and S–C–S angles respectively.
Phosphorylation with Pyrophosphoric Acid
Authors: Yamaguchi Hachiro , Ogura Fumio , Otsubo Tetsuo , Ikeura Yasuhiro
Published: July 2006

Dihydrogenphosphates of primary and secondary aliphatic alcohols as well as phenol were prepared by a very simple procedure with pyrophosphoric acid. t-Butyl and benzyl dihydrogenphosphates could be obtained by a slight modification of the reaction conditions. For the purpose of phosphorylation pyrophosphoric acid was more reactive than orthophosphoric acid.
A Convenient Preparation of Some N-Alkylcarbazoles and N-Alkylacridones
Authors: Nishi Hisao , Kohno Hisao , Kano Toshihiro
Published: July 2006

N-Alkylation of aromatic compounds involving nitrogen heterocycles such as carbazole and acridone with alkyl halide in the presence of caustic solution and benzyl triethyl ammonium chloride (BTEAC) as a phase-transfer catalyst readily proceeded under mild conditions. These results show that this procedure is effective for the preparation of the title compounds in high yields.
Photolysis of Dispiro-substituted 3-Thioxo-1-cyclobutanones
Authors: Kimura Koji , Fukuda Yoshihiro , Negoro Toshihiko , Odaira Yoshinobu
Published: July 2006

Photolysis of dispiro-substituted 3-thioxo-1-cyclobutanones in dichloromethane or even in methanol gave rise to the photoisomerization to afford thiolactones preferentially.
TiO2-supported Noble Metal Catalysts for the NO–CO and NO–CO–H2O–H2–O2 Reactions
Authors: Nakamura Ryuichi , Nakai Shuichi , Sugiyama Kazuo , Echigoya Etsuro
Published: July 2006

TiO2-supported noble metal catalysts, such as Pt–, Pd–, and Rh–TiO2, are much more active for the NO–CO reaction in the presence or absence of H2O, H2, and O2 than the corresponding Al2O3– or other supported catalysts. They are effective even in an oxidative gas composition range for the NO–CO–(H2O)–H2–O2 reaction, producing no NH3 in the NO–CO–H2O reaction. Comparison of the catalytic activity and properties of Pt–TiO2 with those of other supported catalysts suggests that the higher activity of the TiO2-supported catalysts could be attributed to their ability to activate NO molecules by the dissociative adsorption at lower temperatures.
The Stereochemistry and Reactivity of Metal-Schiff Base Complexes. IV. The Stereoselectivity of N,N′-Ethylenebis(α-methylsalicylideneaminato)cobalt(III) Complexes with N-Benzyl-l-alanine, N-Methyl-l-alanine, and N-Benzyl-N-Methyl-l-alanine, and the Stereospecificity of [1S, 2S)-N,N′-1,2-Cyclohexylenebis(salicylideneaminato)cobalt(III) Complexes toward N-Benzyl-l-alanine
Authors: Fujii Yuki , Matsufuru Makoto , Saito Akira , Tsuchiya Sakiko
Published: July 2006

Cobalt(III) complexes containing N-alkyl-l-alanine and a Schiff base ligand, β2-[Co(α-Me-sal2en)(N-R-l-ala)] (where α-Me-sal2en represents the dianion of N,N′-ethylenebis(a-methylsalicylideneamine) and N-R-l-ala denotes the anion of titled amino acids), have been prepared. They were characterized by the use of the absorption, circular dichroism, and 1H NMR spectra of the complexes. They showed quite high stereoselectivity for ΛRS-β2-configuration: 93% for N-methyl-l-alanine, and almost 100% for N-benzyl-l-alanine and N-benzyl-N-methyl-l-alanine. The similar β2-Co(sal2-(S,S-chxn) complexes with N-benzyl-l- and N-benzyl-d-alanines, where sal2-(S,S)-chxn represents the dianion of (1S,2S)-N,N′-1,2-cyclohexylenebis(salicylideneamine), have been synthesized to investigate the stereospecificity of the complex toward N-benzyl-l-alanine. It was found that Co(sal2-(S,S)-chxn) complex reacts with N-benzyl-l-alanine in a high stereospecificity (93–94% at the 1 : 2 reaction molar ratio between the complex and racemic N-benzylalanine, and almost 100% at the 1 : 100 molar ratio). The above phenomena were explained in terms of the thermodynamic selectivity of the complexes.
Acetylenic and Polyacetylenic Compounds Derived from Thiophene, Furan, and p-Dibromobenzene Using 1,1-Dichloro-2,2-difluoroethene
Authors: Okuhara Kunio
Published: July 2006

Compounds of the type AZCF=CCl2, prepared from AZA (thiophene, furan, and p-dibromobenzene; Z=2,5-thiophenediyl, 2,5-furandiyl, and p-phenylene; A=H or Br), were converted into CCl2=CFZC≡CH, CCl2=CFZC≡CCF=CCl2, and CCl2=CFZC≡CSi(CH3)3 in a one-flask procedure via LiZC≡CLi. The products were further converted into acetylenic compounds such as (CH3)3SiC≡CZC≡CSi(CH3)3 and (CH3)3SiC≡CZC≡C–C≡CSi(CH3)3. 1-Ethynyl-4-(1,3-butadiynyl)benzene was isolated. 2,5-Diethynylthiophene and -furan were prepared in two steps from thiophene and furan, respectively, via CCl2=CFZCF=CCl2. By treatment with copper (II) acetate hydrate in pyridine, (CCl2=CFZC≡C–)2 were obtained not only from CCl2≡CFZC≡CH but also from CCl2=CFZC≡CSi(CH3)3.
Reactivity of Peroxomonophosphoric Acid in the Oxidation of Benzaldehydes and Dimethyl Sulfoxide in Aqueous Ethanol
Authors: Ogata Yoshiro , Sawaki Yasuhiko , Tsukamoto Yasuyuki
Published: July 2006

Oxidation of benzaldehydes and dimethyl sulfoxide with peroxomonophosphoric acid (PMPA) has been studied in 40% aqueous EtOH in order to examine the reactivity of undissociated and dissociated PMPA in comparison with that of peroxycarboxylic acid. The reactivity for DMSO was in the order RCO3−>H3PO5>H2PO5−>RCO3H>HPO52−. As in the peroxycarboxylic acid oxidation, PMPA oxidation of substituted benzaldehydes afforded phenols by aryl migration and benzoic acids by hydride migration. The product ratio changed with substituents and pH; salicylaldehyde (o-HO) gave only catechol by aryl migration, while p-chloro and unsubstituted benzaldehydes afforded benzoic acids predominantly. The oxidation of aldehydes bearing p-MeO and p-Me was a borderline case and the migratory ratio of Ar∼/H∼ was higher at lower pH, i.e., the order being H3PO5>H2PO5−>HPO52−. The substituent effect in the apparent kobsd values was very small (i.e., ρ≈0), but the effect for aryl migration (kAr∼) estimated from product selectivity gave ρ=−2.88(σ). The rate for hydride migration (kH∼) resulted in ρ=1.7 and 2.0 (σ). Reactivity of PMPA in each dissociated form was compared with that of RCO3H.
An Occurrence of Attractive Alkyl-Phenyl Interaction. The Conformations of Several 1-Phenyl-2-alkanols
Authors: Zushi Shoji , Kodama Yoshio , Fukuda Yoshimasa , Nishihata Ken , Nishio Motohiro , Hirota Minoru , Uzawa Jun
Published: July 2006

The conformations have been studied, by means of NMR spectroscopy, for a series of 1-alkyl-substituted 2-phenylethyl alcohols with the structure C6H5CH2CH(OH)–R, where R=CH3 (1), C2H5 (2), i-C3H7 (3), and t-C4H9 (4). It has been suggested that a rotamer in which the phenyl group is oriented gauche to the alkyl (R) and anti to the hydroxyl group is most populated in the conformational equilibria of 1–3. Another rotamer (in which Ph is anti to R) has, on the other hand, been suggested to be preferred in the conformational equilibrium of 4. The results have been discussed in the light of the presence of an attractive alkyl-phenyl interaction (CH–π interaction).
Insertion of Carbon Monoxide into Nickel-Alkyl Bonds of Monoalkyl-and Dialkylnickel(II) Complexes, NiR(Y)L2 and NiR2L2. Preparation of Ni(COR)(Y)L2 from NiR(Y)L2 and Selective Formation of Ketone, Diketone, and Aldehyde from NiR2L2
Authors: Yamamoto Takakazu , Kohara Teiji , Yamamoto Akio
Published: July 2006

Reactions of monoalkylnickel(II) complexes, NiR(Y)L2 (R=CH3, C2H5; Y=Cl, suc(succinimido), pht(phthalimido), OC6H4-p-CN; L=1/2 bpy (2,2′-bipyridine), PEt3 (triethylphosphine)), with CO afford monoacylnickel(II) complexes, Ni(COR)(Y)L2, which are characterized by elemental analysis and spectroscopies (IR and NMR). Reactions of the acylnickel(II) complexes with alcohols and aniline give the corresponding esters and amides, respectively. Exposure of Ni(COR)(Y)L2 to dry air leads to oxidation of RCO to a RCOO ligand giving a complex formulated as Ni(OCOR)(Y)L2. Reactions of dimethylnickel(II) complexes, Ni(CH3)2L2 (L=1/2 bpy, PEt3, 1/2 dpe (1,2-bis(diphenylphosphino)ethane, 1/2 dpp (1,3-bis(diphenylphosphino)propane), with carbon monoxide afford acetone and/or 2,3-butanedione in medium to high yields, the acetone/2,3-butanedione ratio varying with the ligand L, reaction temperature, and additives such as maleic anhydride and triphenylphosphine. Generally the acetone/2,3-butanedione ratio decreases with increase in thermal stabilities of Ni(CH3)2L2. Ni(C2H5)2(bpy) and Ni(n-C3H7)2(bpy) give 3-pentanone and 4-heptanone, respectively, on treating them with CO, whereas Ni(C2H5)2(dpe) produces C2H5CHO and C2H4.
ESR Study of the Spin-labeled Poly(methyl methacrylate) Adsorbed on the Human Tooth and Hydroxyapatite
Authors: Sakai Harutoshi , Asakura Tetsuo , Suzuki Kazuomi , Horie Kozo , Maeshima Yukihiro , Imamura Yoshio
Published: July 2006

The motion and the configurational behavior of the poly(methyl methacrylate) adsorbed on the surfaces of human tooth substances (dentin, enamel, and hydroxyapatite crystal) from a solution were clarified by using the electron-spin-resonance technique. The polymer molecules were more strictly bound by the surfaces of enamel and hydroxyapatite than the dentin. On both enamel and hydroxyapatite, the adsorbed molecules behaved in the same manner in their motion and configuration. However, the segments directly bound by each tooth substance had a much higher degree of motional freedom than those by the silica surface. These results were discussed in relation to the interaction between the polymer and the tooth, and in relation to the clinical adhesive aspects.
Ultrasonic Investigation on the Structure of Aqueous Solutions of N,N-Dimethylformamide and Dimethyl Sulfoxide
Authors: Subbarangaiah Kopparapu , Murthy Neriyanuri Manohara , Subrahmanyam Saraswatula Venkata
Published: July 2006

The effects of N,N-dimethylformamide and dimethyl sulfoxide on the temperature of adiabatic compressibility minimum (Tβ) and sound velocity maximum (Tu) of water have been studied. The structural contributions to the shift in Tβ and Tu, [ΔTβ str.]exp. and [ΔTu str.]exp., have been found to be negative for both solutes. Both [ΔTβ str.]exp. and [ΔTu str.]exp. are higher for dimethyl sulfoxide than N,N-dimethylformamide indicating that the sulfinyl group (Remark: Graphics omitted.) is more efficient in structure disruption than the formylimino group (Remark: Graphics omitted.). The results have been explained in the light of hydrogen bonding equilibria by the solutes.
Effect of Hydrogen Bonding on the Phosphorescence of Benzo[c]cinnoline in Polyhydric Solvents
Authors: Inoue Hiroyasu , Hiroshima Yukimi , Tomiyama K\={o}ichi
Published: July 2006

Phosphorescence of benzo[c]cinnoline has been found to be enhanced in polyhydric solvents, such as ethylene glycol, glycerol, and aqueous ethanol. Enhancement of the phosphorescence emission can be attributed to the formation of the hydrogen bond in the triplet state of benzo[c]cinnoline with the solvent molecules.
Magnetic Properties of Copper(II) Complexes of Phenylboronic Acid
Authors: Emori Shuji , Masuo Hisayasu , Muto Yoneichiro
Published: July 2006

The magnetic susceptibilities of copper (II) phenylboronate obey the Bleaney-Bowers equation for dinuclear clusters. The exchange integral within the dinuclear copper(II) phenylboronate, J⁄k, is equal to −195 K. The structures for hydrolysis products of copper(II) phenylboronate are presumed to contain copper(II) phenylboronate dinuclear units connected together by diborate bridges.
The Synthesis of Anthglutin and Its Analogues
Authors: Kinoshita Takeshi , Watanabe Hiroko , Minato Sadamasa
Published: July 2006

Anthglutin (1-γ-l-glutamyl-2-(2-carboxyphenyl)hydrazine) and its analogues were synthesized. Their inhibitory activity on γ-glutamyl transpeptidase was measured. 2-Carboxyphenyl derivatives, including anthglutin, showed inhibitory activity, while the other derivatives did not. The 2-carboxyl group seems to be essential for the inhibitory activity.
Electrical and Optical Properties of a Stable Synthetic Metallic Polymer: Polypyrrole
Authors: Watanabe Atsushi , Tanaka Masashi , Tanaka Jiro
Published: July 2006

Absorption and reflection spectra of the polypyrrole films prepared by electrochemical polymerization are shown over the wide wavelength region and the best fit of the calculated reflection spectra is presented to the observed spectra. Electrical conductivity of the film is measured as a function of temperature and a plot of logσ vs.  T−1⁄4 gives a straight line over the 4.2–300 K region. Furthermore, the thermoelectric-power, S, of the polypyrrole film is shown in the form of S  vs.  T on a linear scale. Based on these results, the conduction mechanism of polypyrrole film is discussed.
Preparation of Graphite Intercalation Compounds of Thiazyl Salts
Authors: Nakajima Tsuyoshi , Kawaguchi Masayuki , Watanabe Nobuatsu
Published: July 2006

Thiazyl salts prepared from S3N3Cl3 and MCl3(M=Sb, Fe, Al) were intercalated into flaky or powdery natural graphite in CCl4 or SOCl2. Intercalation compounds prepared are C24S4N4·2SbCl5[2nd stage, Ic(repeat distance)=12.81±0.02 Å], C9.5·0.2(S3N3Cl3·FeCl2)·0.8(SOCl2·FeCl2) [2nd stage, Ic=12.77±0.03 Å], C11S3N3Cl3· 2.4FeCl2 [a mixture of 1st and higher stage compounds, Ic=9.17±0.05 Å] and C24·0.4(S3N3Cl3·2AlCl2)·0.6(SOCl2·2AlCl2) [a mixture of 2nd and 3rd stage compounds, Ic=12.89±0.03 Å, 16.23±0.03 Å]. Electrical conductivity of pyrolytic carbon–S4N4·2SbCl5 [3rd stage] is higher than that of original pyrolytic carbon by one order.
Synthesis of β-Substituted Tetramethyltetraazacyclotetradecatetraene and Its Metal(II) Complexes
Authors: Tokumitsu Takao , Hayashi Takayuki
Published: July 2006

N,N′-Bis(1-methyl-3-thioxo-1-butenyl)ethylenediamine (3) was prepared by the reaction of N,N′-bis(1-methyl-3-oxo-1-butenyl)ethylenediamine with phosphorus pentasulfide in pyridine. The reaction of 3 with ethylenediamine gave 5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradeca-4,6,11,13-tetraene (4) in a 46% yield. The reactivity of the β positions of 4 and its metal(II) complexes (M=Cu, Ni, Pd) toward various electrophilic reagents was explored, and some β,β′-bissubstituted tetraaza macrocyclic compounds (substituent=Cl, SC6H4NO2(o), N2Ph) and their metal complexes were prepared, respectively. The former also reacted with metal(II) acetates to afford the same metal complexes.
Studies on Characteristics of Electron Capture Responses. V. Estimation of Electron Attachment Mechanisms from Carrier Gas Flow-rate Dependence of Electron Capture Coefficients
Authors: Takeuchi Masahiro
Published: July 2006

The electron capture coefficients, K, denned by Wentworth et al. were measured for several samples in various carrier gas flow-rates, F, by a pulse sampled electron capture detector (ECD). The carrier gas flow-rate dependence of K, i.e., the plot of K  versus  F, is discussed from the viewpoint of the kinetic theory. The results reveal that the flow-rate dependence of K can be used for estimating the electron attachment mechanisms.
Sorption Behavior of Low Molecular Weight Organic Vapors on β-Cyclodextrin Polyurethane Resins
Authors: Mizobuchi Yoshikazu , Tanaka Minoru , Kawaguchi Yoshihiro , Shono Toshiyuki
Published: July 2006

The sorption behavior of low molecular weight organic vapors on β-cyclodextrin polyurethane resins was estimated from desorption or breakthrough experiments and compared with that on the commercially available resins. Temperature-programmed desorption patterns show that the β-cyclodextrin resins interact strongly with benzene vapor in a nitrogen or air stream. This strong interaction presumably results from the hydrophobic interaction of benzene with the β-cyclodextrin cavity. From the breakthrough experiments using the gas stripping method, it was found that the resin prepared by reacting β-cyclodextrin with 1,3-bis(isocyanatomethyl)cyclohexane, β-H6XDI-P-6.0-M, retains the polar volatile organic compounds more than Amberlite XAD-7 does.
Kinetics of the Oxidation of Ethylenediaminetetraacetato and N-(2-Hydroxyethyl)ethylenediamine-N,N′,N′-triacetato Complexes of Cobalt(II) by Hydrogen Peroxide in Aqueous Acidic Medium
Authors: Banerjee Pradyot , Pujari Mahesh P
Published: July 2006

Kinetics of the oxidation of Co(II) complexes, Co(edta)2− and Co(hedta)− [H4edta=ethylenediaminetetra-acetic acid and H3hedta=N-(2-hydroxyethyl)ethylenediamine-N,N′,N′-triacetic acid] have been studied in aqueous acidic medium (pH 3.6–4.8) at 30–60 °C. The reactions were shown to exhibit second-order kinetics, first-order in each of the reactants. In the pH range studied, the rates of reaction showed inverse [H+] dependence which could be accounted for in terms of the acid-base equilibrium H2O2\oversetKa\ightleftharpoonsHO2−+H+. Applying the limiting conditions [H+]>>Ka, [H2O2]>>[HO2−], the rate-law is given by d[CoIII−L]⁄dt=2{kH2O2+kHO2−Ka[H+]−1} [CoII−L] [H2O2] where L denotes the general form of the ligand in either case. At 30 °C (I, 0.5 mol dm−3), values obtained are kH2O2=(5.6±0.3)×10−5 mol−1 dm3 s−1, kHO2−=(5.4±0.3)×102 mol−1 dm3 s−1 for the Co(edta)2− complex and kH2O2=(4.5±0.4)×10−5 mol−1 dm3 s−1, kHO2−=(5.1±0.5)×102 mol−1 dm3 s−1 for the Co(hedta)− complex. The corresponding activation parameters are ΔH\eweq=(71±8) kJ mol−1, ΔS\eweq=−(92±23) J K−1 mol−1 (Co(edta)2− system) and ΔH\eweq=(89±2) kJ mol−1 and ΔS\eweq=−(36±4) J K−1 mol−1 (Co(hedta)− system).
Catalysis by Alkaline Earth Metal Oxides. II. The Mechanism of Ethylene Hydrogenation on Magnesium Oxides
Authors: Tezuka Makoto , Inoue Yasunobu , Yasumori Iwao
Published: July 2006

The kinetic study of ethylene hydrogenation on a thermally activated MgO was carried out. The slow step of the reaction changed from the irreversible addition of a hydrogen atom to adsorbed ethylene in the lower temperature range(373–423 K) to the hydrogenation of an ethyl radical in the higher temperature range (523–673 K).
X-Ray Photoelectron Spectroscopic Studies of SbSI
Authors: Ikemoto Isao
Published: July 2006

The binding energies of the core electron peaks suggest that SbSI has more ionic character than covalent character. The valence band spectrum was compared with the calculated density of states. XPS spectra of low temperature ferroelectric phase could not be obtained due to the inhomogeneous spontaneous polarization.
The Halogenation of the N,N′-Ethylenebis(5,5,5-trifluoro-4-oxo-2-pentaniminato)nickel(II) Complex and the Reaction Intermediate
Authors: Fujii Yuki , Ito Masaaki , Akiyama Kunio
Published: July 2006

[Ni(tfac2en)] reacted with NXS (N-chloroor N-bromosuccinimide) in an alcoholic solvent to give the halogenated complexes at the γ-carbon atoms. The reaction intermediate was successfully isolated and was characterized by the use of the 1H-NMR, IR, and AB spectra.
Ligand Dissociation Rate Constants of Tris(4,4′-dimethyl-2,2′-bipyridine)chromium(II) and Tris(5,5′-dimethyl-2,2′-bipyridine)chromium(II) Complexes
Authors: Nakano Kunio , Narusawa Yoshio , Moroi Hiroyuki
Published: July 2006

Ligand dissociations of tris(4,4′-Me2bpy)- and tris(5,5′-Me2bpy)chrornium(II) complexes have been studied by scavenging the ligand with zinc ion according to a stopped-flow method.
Solubility Phase Diagram Containing Racemic Compound of Bis(ethylenediamine)oxalatocobalt(III) Oxalate
Authors: Fuyuhiro Akira , Yamanari Kazuaki , Shimura Yoichi
Published: July 2006

Solubility of Δ- and rac-[Co(ox)(en)2](C2O4)0.5 was measured in water at 5–60 °C, the solubility isotherm of the ternary system, Λ-[Co(ox)(en)2](C2O4)0.5−Δ-[Co(ox)(en)2](C2O4)0.5−H2O being determined at 25 °C. It was found that the oxalate is not spontaneously resolvable and forms the racemic compound, Λ-[Co(ox)(en)2]·Δ-[Co(ox)(en)2](C2O4)·nH2O.
Extraction of Lead(II) in Aqueous Thiocyanate-Perchlorate Solutions wtih Trioctylphosphine Oxide in Hexane and with 4-Methyl-2-pentanone
Authors: Kusakabe Satoshi , Sekine Tatsuya
Published: July 2006

The stability of lead(II) thiocyanate complexes and the extraction behavior of lead(II) in 1 mol dm−3 Na(SCN, ClO4) were studied. By an extraction method with thenoyltrifluoroacetone, logβ1=0.49 was obtained for PbSCN+. The extraction was poor with 4-methyl-2-pentanone but effective with trioctylphosphine oxide in hexane. Not only Pb(SCN)2 but also Pb(SCN)(ClO4) and Pb(ClO4)2 were extracted into both of the solvents.
Isotope Effects in the p-Tolylation of Pyridine
Authors: Nakabayashi Takeshige , Horii Toyokazu , Kawamura Shunichi , Abe Yasuo
Published: July 2006

p-Toluoyl peroxide, p-iodotoluene, and di-p-tolyl sulfone, sulfoxide, and sulfide were photolyzed in an equimolar pyridine-pyridine-d5 mixture to give rise to isomeric p-tolylpyridines (α,β, and γ) and their deuterated compounds. Isotopic distribution ratios (YH/YD) in the isomeric products were determined to be slightly larger than unity.
The Reaction of Dibenzylthiocarbamoyl Chloride with Sodium Nitrite
Authors: Nakajima Masayuki , Herget Rose Ann , Anselme Jean-Pierre
Published: July 2006

The reaction of dibenzylthiocarbamoyl chloride with sodium nitrite in acetonitrile at room temperature yields N-nitrosodibenzylamine, dibenzylcarbamoyl chloride, bis(dibenzylcarbamoyl) disulfide, benzaldehyde, and benzyl isothiocyanate; possible mechanisms for the formation of these products are suggested.
Determination of Thermodynamic Properties of Boehmite from its Solubility Data in NaOH Solutions
Authors: Chang Byong-Tae
Published: July 2006

Thermodynamic properties of boehmite in alkaline pH range are determined by applying the extended Debye-Hückel theory to its solubility data in NaOH solutions. When log(Ks/aw2), where Ks=mHmA1 and aw is the activity of the water in NaOH solutions, is plotted against a Debye-Hückel function of ionic strength (I), I1⁄2⁄(1+Bta1I1⁄2), at a given temperature, the curve approaches gradually the theoretical Debye-Hückel limiting slope (2At) with decrease in the ionic strength, and at high ionic strength it deviates positively from the straight line. Under the assumption of the same ionic size parameters for OH− and Al(OH)4− ions, the ionic solubility product, Ks°=aHaA1⁄aw2, for boehmite is given by following equations in the temperature range from 80 to 250 °C: log Ks°=−2663⁄T−5.71 (Case 1) or log Ks°=−2764⁄T−5.45 (Case 2). From a comparison of the temperature dependences of Ks° for boehmite and gibbsite, a transition temperature between the two alumina hydrates was calculated to be 60±3 °C.