bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies of the Hydrous Silicon(IV)–Titanium(IV) Oxide Ion Exchanger. I. A Method of Synthesis and Some Properties
Authors: Yamazaki Hiromichi , Kanno Yasuhito , Inoue Yasushi
Published: July 2006

Hydrous silicon(IV)–titanium(IV) oxide ion exchanger was prepared by using TiCl4 and Na2SiCO3 solutions. From a detailed examination of the dependency of the compositions and the acid–base properties of the products on the conditions for precipitation, a reproducible synthetic procedure was established. The exchangers with 37 to 67 mol% of titanium to metallic elements possess much larger ion-exchange capacities and are more stable to highly alkaline solutions than simple mixtures of hydrous silicon(IV) oxide and hydrous titanium(IV) oxide. The dependency of the ion-exchange capacity on the composition can be explained by the difference in the structure of the matrix as evidenced from the thermal analysis, X-ray diffraction, and infrared absorption studies.
Preparation of Superconductive Films by Fume Pyrolysis
Authors: Ogawa Takao , Yamada Seiji , Miki Takeshi , Tsuiki Hideyasu , Kakuta Noriyoshi , Ueno Akifumi , Suzuki Yasuji , Koyama Kuniyuki , Noguchi Seiichiro , Yamada Mamoru
Published: July 2006

Superconductive films composed of Ba2YCu3O7−δ were prepared by fume pyrolysis with a temperature programmed electric furnace. Fumes generated from an aqueous solution of Ba, Y, and Cu nitrates with an aid of supersonicant were introduced into the furnace with flowing O2. Fine particles consisting of Ba, Y, and Cu ions were formed in the furnace and deposited on the surface of a YSZ substrate placed at the top of the furnace. Films thus prepared and annealed at 1273 K showed superconductive properties below 90 K and zero resistivity was observed at 80 K with 100 μA of the current.
On the Reaction of N-Vinyliminophosphoranes. 9. The Synthesis and Reaction of N-(1,3,5-Cycloheptatrienyl)iminophosphoranes to Provide a Novel Route to 1-Azaazulenes
Authors: Iino Yukio , Hara Eijiro , Nitta Makoto
Published: July 2006

The first syntheses of N-(2,4,6-cycloheptatrienyl)iminophosphoranes (3a, b) and their thermal conversion to N-(1,3,5-cycloheptatrienyl)iminophosphoranes (5a,b) have been studied. The kinetic study of the 1,5-hydrogen migration of 3a,b to N-(1,3,6-cycloheptatrienyl)iminophosphoranes (4a,b) has also been investigated. The reaction of 5b with α-bromoacetophenone derivatives has provided a novel route to the 1-azaazulene ring system, albeit in low yields.
The Selective Claisen and Dieckmann Ester Condensations Promoted by Dichlorobis(trifluoromethanesulfonato)titanium(IV)
Authors: Tanabe Yoo
Published: July 2006

Inter and intramolecular condensations (the Claisen and the Dieckmann condensations) between ester functions have been performed by the combined use of dichlorobis(trifluoromethanesulfonato)titanium(IV) (= dichlorobis(triflato)titanium(IV)) and tertiary amine under mild reaction conditions. These results led to the development of the selective (crossed) Claisen and Dieckmann ester condensation between methoxymethyl ester and methyl ester, in that, dichlorobis(triflato)titanium(IV) contribute to control the direction of the reaction.
High-Resolution Nuclear Magnetic Resonance Study of 6-O-α-d-Glucopyranosyl-α-cyclodextrin-p-Nitrophenol Inclusion Complex in Aqueous Solution
Authors: Kanda Yoshihiro , Yamamoto Yasuhiko , Inoue Yoshio , Ch\ {u}j\ {o} Riichirô , Kobayashi Shôichi
Published: July 2006

6-O-α-d-Glucopyranosyl-α-cyclodextrin (G1-α-CD)-p-nitrophenol (pNP) inclusion complex has been characterized by high resolution 1H and 13C NMR. From 1H NMR measurements it is concluded that G1-α-CD forms a 1 : 1 inclusion complex with pNP at both pD 7 and 10, and the dissociation constants for their complexation are quite similar to those for α-CD–pNP complexation, suggesting that G1-α-CD and α-CD have a similar ability of complexation with pNP. The geometry of G1-α-CD–pNP complex was found to be similar to that of α-CD–pNP complex. Analysis on the NMR spectral parameters of G1-α-CD have revealed that the asymmetric nature of G1-α-CD molecule is enhanced by complexation with pNP.
No Electron-Donating Substituent Effect on the Singlet Excited State Formation from the 5-(5-Aryl-2-pyrazinylamino)-1,2,4-trioxanes in Dimethyl Sulfoxide Triggered by Potassium t-Butoxide
Authors: Teranishi Katsunori , Goto Toshio
Published: July 2006

5-(5-Phenyl-2-pyrazinylamino)-1,2,4-trioxane derivatives having a substituent on the 4 position of the phenyl group gave chemiluminescence in dimethyl sulfoxide by addition of potassium t-butoxide. No electron-donating substituent effect was observed on the yield of singlet excited state formation. This may be explained by the negative charge formed on the nitrogen atom next to the transient dioxetane moiety, which may produce singlet excited-state molecule by the intramolecular CIEEL mechanism.
ENDOR Studies of the Complexation Reaction between Spin-Labeled Crown Ether and Alkali Metal Salts
Authors: Tajima Kunihiko , Miyoshi Masanao , Furutani Masahiro , Fujimura Yasushi , Mukai Kazuo , Ishizu Kazuhiko
Published: July 2006

A new crown ether spin-labeled by the phenoxyl radical moiety was prepared. Intramolecular odd-π electron delocalization was investigated by means of ENDOR spectroscopy. On the basis of ENDOR spectrometric titration, the equilibrium constant for Na+-labeled crown-ether-complex formation was evaluated to be pKNa+=3.5 in 2-propanol at −30 °C.
Halogenation Using Quaternary Ammonium Polyhalides. XIX. Aromatic Chlorination of Arenes with Benzyltrimethylammonium Tetrachloroiodate
Authors: Kajigaeshi Shoji , Ueda Yasuhiro , Fujisaki Shizuo , Kakinami Takaaki
Published: July 2006

The reaction of arenes with a calculated amount of benzyltrimethylammonium tetrachloroiodate ir acetic acid at room temperature or at 70 °C gave nuclear chloro-substituted arenes in fairly good yields.
Formation of Furan Derivatives from Phenacyl Bromides and Sodium Telluride; Attempted Extension to Coumarin Synthesis
Authors: Padmanabhan Seetharamaiyer , Ogawa Takuji , Suzuki Hitomi
Published: July 2006

The enolates, generated from phenacyl bromides by sodium telluride, yield 2,4-diarylfurans in addition to the expected dehalogenation products. No 1,4-dicarbonyl compounds could be isolated even in the presence of excess oxidizing agent, copper(II) chloride. Condensation of 2-(methoxymethoxy)arenecarbaldehydes with ethyl bromoacetate in the presence of sodium telluride gave the expected α,β-unsaturated esters which resisted cyclization to yield the desired coumarin derivatives. Attempted intramolecular Reformatsky-type reaction of 2-(bromoacetoxy)benzaldehyde gave only 6,12-epoxy-6H,12H-dibenzo[b,f]-[1,5]dioxocin as the major product.
Generation of an N-Sodioazomethine Ylide and Its Cycloadditions with α,β-Unsaturated Esters
Authors: Kanemasa Shuji , Yoshioka Manabu , Tsuge Otohiko
Published: July 2006

Treatment of methyl 2-(benzylideneamino)propanoate with sodium hydride in THF generates an N-sodioazomethine ylide, which shows a very poor stereoselectivity in the cycloaddition with methyl acrylate. However, addition of such a base as triethylamine or t-butyl alcohol improves the selectivity. Chemical properties of the ylide have been discussed on the basis of the selectivity totally different from that of N-lithio analogue.
Total Syntheses of (+)-Altholactone [(+)-Goniothalenol] and Three Stereocongeners and Their Cytotoxicity against Several Tumor Cell Lines
Authors: Ueno Yoshihide , Tadano Kin-ichi , Ogawa Seiichiro , McLaughlin Jerry L , Alkofahi Ahmad
Published: July 2006

Enantiospecific total synthesis of (+)-altholactone [(+)-goniothalenol] (1), a novel tetrahydrofuropyran-5-one possessing significant cytotoxicity against several tumor cell lines, has been achieved by using l-arabinose as the redundant starting material. The pivotal tetrahydrofuran formation was realized by treatment of the diastereomeric mixture of (2S,3R)-4,5-epoxy-5-phenyl-1,2,3-pentanetriol 1,3-benzylidene acetals 8 and 8′ with silica gel. Simultaneous stereochemical inversion at C-4 and C-5 of the major cyclization product, O,O′-benzylidene derivative of (2S,3R,4S,5S)-2-(hydroxymethyl)-5-phenyltetrahydrofuran-3,4-diol (11), to the 2S,3R,4R,5R diastereomer 10 was achieved by hydroboration of (2S,3S)-3-hydroxy-2-(hydroxymethyl)-5-phenyl-2,3-dihydrofuran O,O′-benzylidene derivative (18) which derived from 11. Pfitzner-Moffatt oxidation of 10 followed by NaBH4 reduction gave the 2S,3R,4S,5R diastereomer 20 exclusively. Displacement of the triflate group in (2S,3R,4S,5S)-2-(hydroxymethyl)-5-phenyl-4-[(trifluoromethylsulfonyl)oxy]tetrahydrofuran-3-ol O,O′-benzylidene derivative (21) by acetate, which was prepared from 11, furnished the 2S,3R,4R,5S diastereomer 22. The total synthesis of 1 was completed by Collins oxidation of (2S,3R,4R,5R)-2-(hydroxymethyl)-3,4-bis(methoxy-methoxy)-5-phenyltetrahydrofuran (34), which was prepared from 10, and subsequent Witting olefination with (ethoxycarbonylmethylene)triphenylphosphorane followed by hydrolysis. By employing the analogous reaction sequence, compounds 11, 20, and 22 were efficiently converted into (+)-7,8-di-epi- (2), (+)-7-epi- (3), and (+)-8-epi-altholactone (4), respectively. The cytotoxicity of 1–4 against several tumor cell lines was examined.
Substituent-Group Effects on the Fluorescence of Aluminum–Schiff Base Complexes and Their Application to the Determination of Aluminum
Authors: Aoki Izuo , Matsunaga Toshiaki , Watanabe Kunihiro
Published: July 2006

The effects of the substituents in the Schiff-base N-salicylidene-o-aminophenol (SOAP) on the fluorescence of its aluminum complexes were investigated. N,N′-Disalicylideneethylenediamine (DSED) derivatives were used as aldehyde reagents for the condensation to prepare 25 different SOAP compounds, for these reagents can be conveniently hydrolyzed to yield salicylaldehyde derivatives. o-Aminophenol (OAP) derivatives were used as amine reagents for the SOAP compounds. A methoxyl group at the 4-position of the benzylidene group in the Schiff base and a sulfo group at the 5-position in the amine component increased the fluorescence intensity of the complex. The relationship between the fluorescence intensity and the structure of the complex was investigated by the Free-Wilson method of estimation, and good agreements were obtained between the experimental and the calculated values of the fluorescence intensities. The fluorometric determination procedure of aluminum was established by using 4,4′-dimethyl DSED and 4-sulfo OAP. Aluminum can be accurately determined in the range from 0.001 to 3 μg/25 ml under optimum conditions.
Effect of 2,2′-Bipyridine on Nickel(II)-Halide Interactions within Their Ternary Complexes in N,N-Dimethylformamide
Authors: Ishiguro Shin-ichi , Ozutsumi Kazuhiko
Published: July 2006

The formation of ternary (2,2′-bipyridine)bromonickel(II) complexes has been studied by calorimetry in N,N-dimethylformamide containing 0.16 mol dm−3 (C2H5)4-NClO4 as a constant ionic medium at 25 °C. The data are well explained in terms of the formation of [NiBr(bpy)]+ and [NiBr(bpy)2]+ (bpy=2,2′-bipyridine), and their formation constants, enthalpies and entropies were determined. It is elucidated that the affinities of Br− as well as Cl− ions to [Ni(bpy)]2+ and [Ni(bpy)2]2+ are enhanced almost to the same extent over Ni2+. The enhancement is ascribed mainly to an increase in entropies upon complexation in both NiII–Cl−–bpy and NiII–Br−–bpy systems.
The Regioselective Side-Chain Lithiation of 2-Methyl-3-thiophenecarboxylic Acid
Authors: Hui-Wen Su , Hirose Kazuo , Shirai Kozo , Kumamoto Takanobu
Published: July 2006

It was found that the dilithium salt (5), which was lithiated at the side-chain of 2-methyl-3-thiophenecarboxylic acid (4), was produced regioselectively by the reaction of 4 with lithium diisopropylamide (LDA). The reactions of 5 with alkyl halides resulted in the formation of 2-alkyl-3-thiophenecarboxylic acids (7). Further, δ-lactone derivatives (11) were obtained by the cyclization of the adducts (10) which were produced from 5 with aldehydes and ketones.
A Synthetic Route of 1,4,8-Trimethoxy-2-naphthalenecarbaldehyde via Duff Formylation of 4,8-Dimethoxy-1-naphthol
Authors: Tanoue Yasuhiro , Terada Akira , Matsumoto Yasuyuki
Published: July 2006

A convenient route for preparing 1,4,8-trimethoxy-2-naphthalenecarbaldehyde was accomplished by the following: The starting material, 4,8-dimethoxy-1-naphthol, was prepared from 1,5-dimethoxynaphthalene through 1-bromo-4,8-dimethoxynaphthalene. Formylation of this naphthol and subsequent methylation gave 1,4,8-trimethoxy-2-naphthalenecarbaldehyde.
1:1:1 Inclusion Compounds of β-Cyclodextrin with Fluorene and Alcohols or Nitriles in Aqueous Solution
Authors: Hamai Sanyo
Published: July 2006

Fluorene forms a 1:1 inclusion compound (FC) with β-cyclodextrin (CDx) in aqueous solution. From electronic absorption and emission spectra, FC has been found to further associate with alcohol (from ethanol to 1-pentanol) or nitrile (from propionitrile to hexanenitrile) to form a 1:1:1 inclusion compound. An equilibrium constant (K3) for the formation of the 1:1:1 inclusion compound from FC and alcohol, and that (K4) from fluorene and a 1:1 inclusion compound of CDx with alcohol have been determined. Upon going from ethanol to 1-pentanol, the value of K4 increases, reaches a maximum at 1-propanol, and then decreases while K3 monotonously increases with an increase in the alkyl-chain length of alcohol. For nitriles, K3 and K4 have also been evaluated. In this case, the largest K4 value is seen for propionitrile and butyronitrile, while K3 increases with increasing the alkyl-chain length of nitrile.
Equilibrium and Kinetic Studies of the Iron(III) Complex with N-Pyridoxylidene-l-tryptophan: Electronic Absorption and Circular Dichroism Spectral Characteristics, Stability, and Formation and Ligand-Substitution Reaction Mechanisms
Authors: Kuno Hideyuki , Okamoto Ken-ichi , Hidaka Jinsai , Einaga Hisahiko
Published: July 2006

Studies have been made of the electronic absorption and circular dichroism (CD) spectral characteristics, thermodynamic stability, and formation and ligand-substitution reaction kinetics of an iron(III) complex with N-pyridoxylidene-l-tryptophan (Hpdx-l-Htrp). The 1:2 (metal: ligand) complex forms in an acidic aqueous solution with the stability constant (β2) of logβ2=18.38±0.10 mol−2 dm6 (0.50 mol dm−3 (NaCl), 25 °C). The complex shows a characteristic CD spectrum in the charge-transfer region. The kinetics were studied by a stopped-flow CD method in a 0.50 mol dm−3 aqueous NaCl solution at 25 °C. The formation of the complex proceeds through six parallel pathways of Fe3+, FeOH2+, and FeCl2+ with H2pdx-l-Htrp+ and H2pdx-l-trp, with the coordination of the carboxylato group to iron(III) as the rate-determining step. The ligand-substitution reaction of the complex by ethylenediamine-N,N,N′,N′-tetraacetic acid depends neither on the entering ligand nor on the hydrogen-ion concentration. The dissociation of a coordinated Hpdx-l-trp− from [Fe(Hpdx-l-trp)2]+ is concluded to be the rate-determining step. The reaction mechasnisms are discussed in detail.
Ozonization of Thio- and Azauracils
Authors: Matsui Masaki , Kamiya Kazusaki , Kawamura Shigeo , Shibata Katsuyoshi , Muramatsu Hiroshige
Published: July 2006

The reactions of 2-thiouracils and azauracils with ozone have been examined. 2-Thiouracils were ozonized to give the corresponding 4(3H)-pyrimidinones and uracils. Ozone attacks the thiocarbonyl moiety and the desulfurization process to give 4(3H)-pyrimidinones competes with the oxidation process to give uracils. 5-Azauracil was stable for ozone, while 6-azauracil readily reacted with ozone to give parabanic acid.
A High Cis-Stereoselectivity in the Hydrogenation of 6-t-Butyltetrahydropyran-3-one and 2-t-Butyl-1,3-dioxan-5-one
Authors: Senda Yasuhisa , Terasawa Toshiyuki , Ishiyama Jun-ichi , Kamiyama Shin-ichi , Imaizumi Shin
Published: July 2006

Stereochemistry in the hydrogenation of 4-t-butylcyclohexanone and the corresponding oxa- and dioxacyclohexanone was examined. A high cis selectivity was observed in the latter two compounds regardless of the catalyst metals used here. These results were explained in terms of intramolecular nO–πCO interaction, which was supported by 13C NMR chemical shifts of the carbonyl carbons and CNDO/2 calculation.
Rhodium Catalyzed Hydrogenation of Quinolines and Isoquinolines under Water-Gas Shift Conditions
Authors: Murahashi Shun-Ichi , Imada Yasushi , Hirai Yoshiaki
Published: July 2006

Wide variety of quinolines and isoquinolines can be hydrogenated selectively in the nitrogen-containing ring by means of carbon monoxide and water in the presence of catalytic amount of rhodium carbonyl cluster. These reactions provide a useful method for the preparation of 1,2,3,4-tetrahydroquinolines and 1,2,3,4-tetrahydroisoquinolines which are key intermediates for the synthesis of isoquinoline alkaloids and other biologically active nitrogen compounds.
The Fluorescence Quenching of Zinc Porphyrins with the ω-[4-(4-Pyridyl)pyridinio]alkyl Group
Authors: Takahashi Kohshin , Terashima Tetsuo , Komura Teruhisa , Imanaga Hiroto
Published: July 2006

The fluorescence of parent porphyrins in ZnPC2bpy+(n), (PC2bpy+(n), 5-[n-[2-[4-(4-pyridyl)pyridinio]ethoxyl]phenyl]-10,15,20-triphenylporphyrin bromide, n=2,3, and 4), and ZnPC8bpy+(3), (PC8bpy+(3), 5-[3-[8-[4-(4-pyridyl) pyridinio]octyloxy]phenyl]-10,15,20-triphenylporphyrin bromide), was effectively quenched in non-coordinating solvents, such as o-dichlorobenzene and dichloromethane, because the pyridyl group in bpy+ (ω-[4-(4-pyridyl)pyridinio]alkyl group) was coordinated to zinc in porphyrin. On the other hand, the fluorescence of parent porphyrins in ZnPC2bpy+(3), ZnPC2bpy+(4), and ZnPC8bpy+ (3) was partly quenched in such coordinating solvents as N,N-dimethylformamide and pyridine. However, only the fluorescence of the parent porphyrin in ZnPC2bpy+(2) was effectively quenched, even in coordinating solvents. The hydrophobic interaction between the porphyrin ring and bpy+ in ZnPC2bpy+(2) may be considerably large, for bpy+ in ZnPC2bpy+(2) is covalently linked to the ortho position of the phenyl group in ZnTPP, (TPP 5,10,15,20-tetraphenylporphyrin), by a short chain. The emission was effectively quenched by the photoinduced electron transfer from the porphyrin ring to bpy+, because the axial coordination or the hydrophobic interaction gave bpy+ access to the porphyrin ring.
Preparation of Optically Active 1-Aminoalkylphosphonic Acids from Chiral Carbamates and Chiral Ureas
Authors: Oshikawa Tatsuo , Yamashita Mitsuji
Published: July 2006

Optically active 1-aminoalkylphosphonic acids were successfully synthesized from chiral carbamate and urea derivatives which were prepared from such chiral substrates as (−)-menthol, (+)-camphor, and (R)-(+)-and (S)-(−)-(1-phenylethyl)ureas by the actions of aldehydes and triaryl phosphites. 1-Aminoalkylphosphonic acid derivatives, thus prepared, have an (R)-(+)- or (S)-(−)-configuration, depending on the chiral source via a retention of the configuration; i.e., (+)-products were prepared from chiral (+)-carbamate and (+)-urea derivatives, and (−)-products from chiral (−)-carbamate and (−)-urea derivatives.
The J-Like Structures of Azobenzene-Containing Amphiphiles, C10AzoC5N+Br− and C8AzoC5N+Br−
Authors: Okuyama Kenji , Mizuguchi Chiyo , Xu Guiqing , Shimomura Masatsugu
Published: July 2006

Totally synthetic azobenzene-containing amphiphiles C10AzoC5N+Br− and C8AzoC5N+Br− (C31H50N3O3Br and C29H46N3O3Br respectively) were crystallized from their solutions by the solvent-evaporation method. Both crystals are triclinic, with the space group of P\bar1 and Z=2. The unit cell dimensions of the former crystal are a=3.233(5), b=0.854(2), c=0.608(1) nm, α=106.96(8), β=86.6(1), and γ=88.3(1)°. Those of the latter crystal are a=3.0098(6), b=0.8553(2), c=0.6084(1) nm, α=72.99(1), β=92.57(2), and γ=95.64(2)°. The crystal structure of C10AzoC5N+B− was solved by the direct method and refined by the block-diagonal least-squares method: R=0.082 for 2927 observed reflections (2θ<120°, Cu Kα, λ=0.15418 nm). On the other hand, that of C8AzoC5N+Br− was refined by the full-matrix least-squares method: R=0.058 for 2993 reflections (2θ<120°, Cu Kα). The molecular and crystal structures of these compounds are quite similar to those of the homologous compounds, C12AzoC5N+Br− and C6AzoC5N+Br−. That is, the CnAzoC5N+Br− molecules incline about 30° to the bilayer surface to pack in a tail-to-tail fashion. The azobenzene chromophore has a pronounced planarity which makes possible the parallel stacking of adjacent phenyl groups.
Entrained Responses of the Current Oscillation of Polymer Gels to Sinusoidal Stimulation
Authors: Osada Yoshihito , Umezawa Kayo , Yamauchi Aizo
Published: July 2006

The responses of the current oscillation of the water-swollen polymer gels generated by dc current to the sinusoidal stimulation were investigated. The current oscillation was semiquantitatively analyzed by fast Fourier transform and the phase diagram was made up from power spectra. It was found that the entrainment of oscillation occurred in the polymer gels when the frequency of sinusoidal stimulation was closed to that of parent current oscillation. It was also found that the stronger sinusoidal voltage caused the entrainment in wider frequency range.
Halogenation Using Quaternary Ammonium Polyhalides. XX. Bromination of Phenols with Polymer-Bound Benzyltrimethylammonium Tribromide
Authors: Kakinami Takaaki , Suenaga Hiroyuki , Yamaguchi Tadashi , Okamoto Tsuyoshi , Kajigaeshi Shoji
Published: July 2006

Bromo-substituted phenols were obtained quantitatively by passing a solution of phenols in dichloromethane–methanol through a column packed with styrene polymer-bound benzyltrimethylammonium tribromide.
A New Method for the Selective Synthesis of Biphenyl by Dehydrogenative Coupling of Benzene
Authors: Nakada Masahiro , Aimin Yu , Kawakami Shigenobu , Iwaki Shingo , Yamaguchi Tatsuaki
Published: July 2006

A method has been developed for the direct preparation of biphenyl by the thermal dehydrogenative coupling of benzene in the vapor phase on the surface of heater at 1000–1200 °C. Biphenyl was obtained at a high selectivity of more than 94% over the wide range of benzene conversion (3–77%).
Photodecomposition of Kraft Lignin Catalyzed by Titanium Dioxide
Authors: Kobayakawa Koichi , Sato Yuichi , Nakamura Shigeo , Fujishima Akira
Published: July 2006

The photocatalytic reaction of kraft lignin at titanium dioxide photocatalyst was investigated. Kraft lignin was completely decomposed into carbon dioxide and water through dehydrodimers of phenol derivatives constituting kraft lignin, methanol and organic acids such as oxalic and formic acids. Aromatic compounds such as vanillin could not be recovered due to their tendency to dehydrodimerization and the strong oxidizing power of the photo-generated holes by the action of which the dehydrodimers were completely decomposed into carbon dioxide and water. The production of methane, ethane, and ethylene was much smaller than that in the decomposition with hydroxyl radicals in homogeneous solution.
A Convenient Reductive Removal of Benzylic Hydroxyl and Trimethylsilyloxyl Groups with Me3SiCl–NaI–MeCN Reagent
Authors: Sakai Takashi , Miyata Kazuyoshi , Tsuboi Sadao , Takeda Akira , Utaka Masanori , Torii Sigeru
Published: July 2006

Secondary and tertiary hydroxyl groups at benzylic positions were reductively removed by treatment with 6 equivalents of Me3SiCl–NaI–MeCN reagent in hexane at room temperature. A benzylic trimethylsilyloxyl group was also eliminated by the addition of 2 equivalents of water to the reaction system. The reduction was applied to the syntheses of precursors of such anti-inflammatory agents as ibuprofen, butibufen, naproxen, and related compounds, as well as (±)-ar-turmerone, an odorous sesquiterpene.
Reactions of Alkylarenes, Benzyl Alcohols, Sulfides, and Phosphine with Manganese(III) Acetate–Chloride Ions
Authors: Futami Yasuo , Nishino Hiroshi , Kurosawa Kazu
Published: July 2006

The reactions of methoxytoluenes and methylnaphthalenes with a manganese(III) acetate–Cl− complex gave the corresponding aldehydes in 8 to 54% yields. In a similar reaction aromatic compounds having a methylene group were oxidized to the corresponding acetates and ketones. The primary and secondary benzyl alcohols gave aldehydes and ketones, respectively, in good yields. Sulfides and phosphine were oxidized to give oxides by the complex. The reaction of alkylarenes with lower ionization potentials can be explained in terms of an electron-transfer mechanism involving the manganese(III) acetate–Cl− complex.
The Easy Disruption of the β-Sheet Structure of Resin-Bound Human Proinsulin C-Peptide Fragments by Strong Electron-Donor Solvents
Authors: Narita Mitsuaki , Umeyama Hiroshi , Yoshida Toshihiko
Published: July 2006

The β-sheet structure disruption of cross-linked polystyrene resin-bound human proinsulin C-peptide fragments containing Pro residues at suitable intervals was investigated by a solvent titration method in CH2Cl2, mainly using TFE and HMPA as titrating solvents. The easy disruption of the β-sheet structure of resin-bound peptides in CH2Cl2 by TFE and HMPA strongly suggested that the concept of “the peptide segment separation by tertiary peptide bonds” was useful for estimating the β-sheet-structure-disrupted behavior and that the β-sheet structure of the protected peptides having high 〈Pc〉 values could easily be disrupted in a medium electron-acceptor solvent of CH2Cl2 by the addition of a strong electron-donor solvent of HMPA in spite of the electron donor-acceptor interaction between solvents. The present results indicate that effective solvents for solid-phase peptide synthesis by a fragment condensation procedure should be searched by taking the average helix, β-sheet, and coil conformation values, 〈Pα〉, 〈Pβ〉, and 〈Pc〉, of peptide segments into consideration.
Dielectric Relaxation and Intermolecular Association for Various Secondary and Tertiary Alcohols
Authors: Shinomiya Toshiomi
Published: July 2006

The dielectric constants and losses of 2-alkanol (n=4–8), 2-methyl-2-alkanol (n=3–7), six isomeric methylheptanols, and five isomeric nonanols have been measured at the frequencies from 1.35 to 4500 MHz at 15, 25, and 35 °C. The absorption has been resolved into two or three different Debye-like dispersion regions. The first, low-frequency, dispersion region could not be observed for more sterically hindered alcohols, such as several tertiary alcohols. For each alcohol, four concentrations of a linear hydrogen-bonded chain polymer (C1), a chain dimer and trimer (C2), a free monomer (C3), and a nonpolar cyclic polymer (CR) were evaluated by applying a modified Kirkwood–Fröhlich equation to each dispersion region. The equilibrium between C1 and C3 can be considered for more polar alcohols and that between CR and C3 for more sterically hindered alcohols. The mechanism of the relaxation process is discussed in terms of observations of the magnitude and relaxation time for the first region. The free energy of activation increases with increasing alkyl chain length, being about 20–23 for the first region, 16–18 for the second region, and 9–12 kJ mol−1 for the third region.
Gas-Phase Dehydrogenation of Alkylbenzenes on Rh/AlPO4 Catalysts
Authors: M. Bautista Felipa , M. Campelo Juan , García Angel , Luna Diego , M. Marinas José
Published: July 2006

The nonoxidative dehydrogenation of alkylbenzenes (ethylbenzene, propylbenzene, and isopropylbenzene) has been carried out at 693–853 K on rhodium catalysts at 1 wt% supported on two different types of AlPO4. In similar experimental conditions, the specific catalytic activity of the Rh/AlPO4 catalysts is higher than that obtained previously for Ni/AlPO4 (20 wt%) catalysts. Besides, a linear free energy relationship (LFER) was also obtained, manifesting itself through a “compensation effect” between the ΔH≠ and ΔS≠ activation parameters obtained from the Eyring equation (and between ln A and Ea, from the Arrhenius equation). Furthermore, no extensive metal-support interaction effect was obtained as in the case of Ni/AlPO4 catalysts in spite of exhibiting the same concerted mechanism previously described for the nonoxidative dehydrogenation of alkylbenzenes on supported nickel catalysts.
Temperature Change of Graphite Surface Due to Electrochemical Intercalation of ClO4− Ion
Authors: Maeda Yasuhisa
Published: July 2006

Anodic intercalation and cathodic deintercalation of ClO4− ions were shown to cause exothermic and endothermic changes, respectively, on a graphite surface. This suggests the occurrence of an increase in entropy for the deintercalation process and a decrease for the case of intercalation.
Regioselective Hydrogenation of Unsaturated Alcohol Using Platinum–Alumina Modified with Carboxylic Acid
Authors: Kuno Hideyuki , Takahashi Kyoko , Shibagaki Makoto , Matsushita Hajime
Published: July 2006

Platinum–alumina catalysts modified with carboxylic acid were prepared for the selective hydrogenation of unsaturated alcohols. These catalysts were stable in non-polar solvents. It has been demonstrated that the carbon–carbon double bond which is close to the hydroxyl group is preferentially hydrogenated in the case of several hexenols. This selectivity was applied to the regioselective hydrogenation of geraniol and citronellol was obtained in an 84.5% yield over one of the modified catalyst systems.
Synthesis and Characterization of the Pd(II) and Pt(II) Complexes of Trichalcogeno[n]ferrocenophanes (n=7 and 9). A Dative Fe–Pd or Fe–Pt Bond Formation
Authors: Sato Masaru , Asano Hirofumi , Suzuki Kaoru , Katada Motomi , Akabori Sadatoshi
Published: July 2006

1,7-Dithia-4-selena[7]- and 1,9-dithia-5-selena[9](1,1′)ferrocenophanes were prepared. These compounds, as well as 1,4,7-trithia[7]- and 1,5,9-trithia[9](1,1′)ferrocenophanes, were treated with (CH3CN)4Pd(BF4)2 or (CH3CN)4Pt(BF4)2 to give the corresponding 1/1 complexes in good yield. The spectral data of these complexes confirmed that there exsisted a dative Fe–Pd or Fe–Pt bond in these bimetallic complexes.
2,5-Diaryl-1,3,2-dioxaborinanes: A New Series of Liquid Crystals
Authors: Matsubara Hiroshi , Seto Koji , Tahara Tadasu , Takahashi Shigetoshi
Published: July 2006

2,5-Diaryl-1,3,2-dioxaborinane derivatives having various terminal groups were synthesized and found to form mesomorphic phases in a wide temperature range. They provide a new series of liquid-crystalline compounds containing a boron atom in the principal structure.
Model Compound Studies of Coal Liquefaction with Zinc–Butyl Iodide under Mild Conditions
Authors: Yoneyama Yoshiharu , Akaki Yu , Kato Tsutomu
Published: July 2006

A number of model compounds having representative coal structures were treated with zinc–butyl iodide under mild conditions. Gas chromatography and gas chromatography/mass spectrometry were used to identify the reaction products. Polynuclear aromatic compounds gave the butyl-substituted and butyl-addition products. In a reaction of anthracene, its aromatic backbone was cleaved. Alkoxynaphthalene and dibenzyl ether were butylated along with cleavage of ether linkage, while diphenyl ether gave only the butyl-substituted products without cleavage. Butylation and cleavage also took place in the reactions of diphenylmethane and bibenzyl. In the cases of substitution reaction, some butyl groups were rearranged to s-butyl. Because the formation of the most reaction products is interpreted by a similar mechanism to that of Friedel–Crafts alkylation and the formation of some butyl-addition products of polynuclear aromatic compounds is explained by assuming a radical reaction mechanism, it is suggested that both alkyl cation reaction and alkyl radical reaction occur competitively.
Formation of a Hydrogen Insertion Compound of Hydrated Molybdenum Oxide from Hydrogen Molybdenum Bronze
Authors: Eda Kazuo , Sotani Noriyuki
Published: July 2006

It was found that hydrogen molybdenum bronze, H0.3MoO3, turns into a hydrogen insertion compound of hydrated molybdenum oxide in a 1M HCl aqueous solution at 353 K. It was predictable that the compound has a composition of H0.15MoO3·0.88H2O and is identical with Mo8O15(OH)16 or a similar compound.
The Magnetic Properties of Copper(II) 3- and 4-Substituted Benzoate Adducts with Quinoline and 4-Methylquinoline
Authors: Emori Shuji , Matsunaga Satoru , Goto Miyako
Published: July 2006

Various copper(II) 3- and 4-substituted and 3,5-disubstituted benzoate adducts with quinoline and 4-methylquinoline have been prepared, and characterized by means of magnetic susceptibility and IR spectroscopy measurements. The variation of their magnetic moments is discussed in terms of the acidities of their parent acids and the resonance effects of 4-substituents.
Liquid-Crystalline Behavior and Configuration Change of Polyitaconates with Methoxyazobenzene as Mesogens
Authors: Shiraishi Kohei , Sugiyama Kazuo , Otsu Takayuki
Published: July 2006

Nematic polyitaconates having 4-methoxyazobenzene moieties as mesogen in the side chain were prepared. Thermal properties, polymer composition, and the photoinduced configuration change have been examined to suggest a possible use of the polymers for photosensitive liquid-crystalline materials.
Footprint Catalysis. III. Inducible Alteration of Substrate Specificities of Silica(Alumina) Gel Catalysts for 2,4-Dinitrophenolysis of Toluic Anhydrides by Footprint Imprinting
Authors: Morihara Kensaku , Tanaka Eiko , Takeuchi Yuko , Miyazaki Kazue , Yamamoto Nami , Sagawa Yoshimi , Kawamoto Eriko , Shimada Toyoshi
Published: July 2006

A tailor-made catalyst design was attempted for a required substrate specificity by the authors’ footprint imprinting method. Two silica(alumina) footprint catalysts were prepared by imprinting with N-benzoylbenzenesulfonamide (1) and N-(p-toluoyl)-p-toluenesulfonamide (2) from the same aluminum ion-doped silica gel. Their catalytic effects upon 2,4-dinitrophenolysis of benzoic anhydride, p-, m-, and o-toluic anhydrides were compared in order to find any difference in substrate specificities. The catalyst prepared by imprinting with 1 showed the largest specificity(kcat⁄Km) toward benzoic anhydride, whereas the catalyst prepared with 2 showed the largest specificity toward p-toluic anhydride. This finding evidently demonstrated that the substrate specificities of footprint catalytic sites are alterable, as required through selecting appropriate transition state analogs as template molecules for footprint marking.
Studies on Mixed Chelates. XVI. Mixed Copper(II) Chelates with 1,2-Dipiperidinoethane and β-Diketonates
Authors: Fukuda Yutaka , Cho Masako , Sone Kozo
Published: July 2006

1,2-Dipiperidinoethane (dipe) forms mixed chelates of the type [Cu(dike)(dipe)]ClO4 with Cu(ClO4)2 and various β-diketonate ions (dike); however, hexafluoroacetylacetonate (hfac) forms [Cu(hfac)2(dipe)] instead. The strong solvatochromism of the former, and the high solubility and volatility of the latter, were compared with those of similar chelates studied so far.
Enhancement of Catalytic Activity of Copper Ion-Exchanged Y Type Zeolites for the Decomposition of Nitrogen Monoxide
Authors: Iwamoto Masakazu , Yahiro Hidenori , Kutsuno Takashi , Bunyu Sukehiro , Kagawa Shuichi
Published: July 2006

Catalytic activity of Y zeolites containing copper ions (CuY) for decomposition of nitrogen monoxide was enhanced through additional exchange of other metal ions or evacuation treatment around 923–973 K. In the first case, Co3+ or Ni2+ ions increase the catalytic activity while Ca2+, Mn2+, Fe2+, and Zn2+ diminish the catalytic activity of CuY. In the second case, the catalytic activity of CuY evacuated at 973 K was twice that of CuY without the evacuation treatment, which is discussed in connection with the increment of Cu ions active for the decomposition.
Cis to Trans Photoisomerization of [CoCl2{(CH3)2PCH2CH2CH2P(CH3)2}2]+, [CoCl(H2O){(CH3)2PCH2CH2P(CH3)2}2]2+ and Related Complexes
Authors: Oguni Kazuma , Ohishi Tomoji , Kita Masakazu , Kashiwabara Kazuo , Fujita Junnosuke
Published: July 2006

Ligand field irradiation of cis-[CoCl2{(CH3)2PCH2CH2CH2P(CH3)2}2]+ in methanol and cis-[CoCl(H2O){(CH3)2PCH2CH2P(CH3)2}2]2+ in acetonitrile at 5 °C led to isomerization to the trans isomer with quantum yields of 0.010 and 0.070, respectively. The same cis to trans photoisomerization of [CoCl2(R2PCH2CH2PR2)2]+ (R=CH3, C4H9) occurred with much smaller quantum yields (ca. 1×10−4) and cis-[CoCl2{(C6H5)2PCHCHP(C6H5)2}2]+ was reduced to cobalt(II) species on irradiation.
The Triflic Acid-Catalysed Deacylation and Decarboxylation of Polymethylbenzenecarbonyl Derivatives under Mild Conditions
Authors: Keumi Takashi , Morita Toshio , Ozawa Yoshihiro , Kitajima Hidehiko
Published: July 2006

Sterically hindered acylarenes are deacylated to arenes in good yields on heating in boiling 1,2-dichloroethane containing a catalytic amount of triflic acid and water. Hindered arenecarboxylic acids undergo decarboxylation under the same conditions to give arenes in high yields.
Electrochemical Preparation and Characterization of the Radical Salts of (Phthalocyaninato)nickel, NiPc(SbF6)0.5, and NiPc(AsF6)0.5
Authors: Yakushi Kyuya , Yamakado Hideo , Yoshitake Michiko , Kosugi Nobuhiro , Kuroda Haruo , Sugano Tadashi , Kinoshita Minoru , Kawamoto Atsushi , Tanaka Jiro
Published: July 2006

The single crystals of NiPc(SbF6)0.5 and NiPc(AsF6)0.5 were prepared by means of an electrochemical method. The electrical, magnetic, optical, and structural properties of these crystals were examined. These crystals are isostructural to each other, and exhibit a metallic behavior at least above 200 K. The g-values of the ESR signals remarkably depend upon temperature. By the aid of the low temperature experiments of XANES and reflectance spectrum, the temperature dependence is explained by the model based on the interaction between the small amount of local spins on the Ni atoms and the conduction electrons on the ligand chain. In addition, a sample dependence was found on the ESR properties of the crystals of NiPc(AsF6)0.5. This is attributed to the sample dependence of the concentration of the local spins on Ni atoms. From these considerations, we concluded that the ligand part is mainly oxidized in these partially oxidized salts, in other words the conduction electrons are located on the ligand chain. The bandwidth of the conduction band was estimated to be about 1 eV.
Photochemical Reactions of the Oxoperoxovanadium(V) Complex in an Acidic Aqueous Solution
Authors: Shinohara Nobuyoshi , Nakamura Yayoi
Published: July 2006

The photochemical decomposition of oxoperoxovanadium(V), VO(O2)+, was studied in perchloric acid media. It was found that the irradiation of VO(O2)+ solutions with 313, 365, and 436 nm exciting light resulted in the photoreduction of the complex, and gave VO2+, with an evolution of oxygen. The overall reaction is: 4VO(O2)++4H+–→4VO2++3O2+2H2O. The photochemical reaction mechanism is also discussed.
Dielectric Dispersion and Intermolecular Association for 28 Pure Liquid Alcohols. The Position Dependence of Hydroxyl Group in the Hydrocarbon Chain
Authors: Shinomiya Toshiomi
Published: July 2006

The dielectric constants and losses of 28 linear alcohols, 1-alkanol (n=3–10), 2-alkanol (n=3–10), 3-alkanol (n=5–10), 4-alkanol (n=7–10), and 5-alkanol (n=9 and 10), have been measured at the frequencies from 1.35 to 4500 MHz at 15, 25, and 35 °C. The Kirkwood–Fröhlich equation was modified so that it could be applied to each dispersion region calculated. The concentration C1 of linear hydrogen-bonded chain polymers, which primary dispersion originates, was evaluated by means of this modified equation. The C1 decreases as the hydroxyl group approaches the center of a molecule, except for propanols and butanols, and also decreases with increasing temperature. For isomeric decanols, for example, the percentages of C1 (C1×100⁄C0) against alcohol gross stoichiometric concentration C0 at 15, 25, and 35 °C are about 71, 63, and 53% for 1-decanol, 52, 40, and 29% for 2-decanol, 22, 17, and 12% for 3-decanol, 11, 7, and 6% for 4-decanol, and 8, 6, and 5% for 5-decanol, respectively. The thermodynamic parameters, ΔF\eweq, ΔH\eweq, and ΔS\eweq, were obtained for dipole relaxation and viscous flow . The ΔFτ\eweq decreases, although the ΔHτ\eweq and ΔSτ\eweq increase, as the hydroxyl group approaches the center of a molecule. The ΔFη\eweq increases linealy with the molecular volume, irrespective of the position of the hydroxyl group.
Stabilities in Water and Transfer Activity Coefficients from Water to Nonaqueous Solvents of Benzo-18-crown-6–Metal Ion Complexes
Authors: Takeda Yasuyuki , Kohno Rie , Kudo Yoshihiro , Fukada Naoaki
Published: July 2006

Formation constants in water of 1:1 benzo-18-crown-6 (B18C6)–metal ion complexes and the B18C6 solubility in water were determined at 25 °C by conductometry or potentiometry with ion-selective electrodes and spectrophotometry, respectively. The selectivity sequences of B18C6 for metal ions in water are Pb2+>Ba2+>Sr2+>Ag+>K+>Tl+>Na+>Rb+. In each case of alkali and alkaline earth metal ions, the more closely a metal ion fits into the B18C6 cavity, the more stable is the B18C6–metal ion complex. Although the solvation power of water for an alkali metal ion is not the largest of all solvents, the formation constant of a given B18C6–alkali metal ion complex in water is by far the smallest of all solvents. The transfer activity coefficients (γ) from water to nonaqueous solvents of the B18C6–metal ion complexes were then calculated from the formation constants of the B18C6 complexes, γ values of B18C6 (obtained from solubilities of B18C6), and γ values of the uncomplexed metal ions. The γ value of B18C6 is larger than those of B18C6–alkali metal ion complexes. This shows that when B18C6 forms a complex with an alkali metal ion, the B18C6 complex becomes more soluble in nonaqueous solvents than in water, compared with uncomplexed B18C6.
The First Synthesis and Properties of 2,3-Di-t-butylthiophene. Reaction of 3,4-Di-t-butyl-1,2-dithiete with Dimethyl Acetylenedicarboxylate
Authors: Nakayama Juzo , Choi Keun Soo , Ishii Akihiko , Hoshino Masamatsu
Published: July 2006

Heating 3,4-di-t-butyl-1,2-dithiete (5) with dimethyl acetylenedicarboxylate (5 equiv) in refluxing o-dichlorobenzene affords dimethyl 2,5-di-t-butyl-3,4-thiophenedicarboxylate (6) (44%), dimethyl 2,3-di-t-butyl-4,5-thiophenedicarboxylate (7) (5%), tetramethyl 1,4-dithiin-2,3,5,6-tetracarboxylate (8) (4%), and tetramethyl 2,3,4,5-thiophenetetracarboxylate (9) (43%). Mechanism of the formation of these products is discussed. Treatment of the hindered ester 7 with lithium 1-propanethiolate affords 2,3-di-t-butyl-4,5-thiophenedicarboxylic acid (13) in 59% yield, which can be decarboxylated by treatment with copper powder to give 2,3-di-t-butylthiophene (4) in 88% yield. The thiophene 4 rearranges to 2,4-di-t-butylthiophene (1) on treatment with aluminum chloride. Oxidation with m-CPBA affords the corresponding sulfone (23). Electrophilic substitutions (bromination and nitration) of 4 occur exclusively at the less hindered and more electronically favored 5-position.
Dielectric Relaxation and Intermolecular Association of Alicyclic Alcohols in Liquid and Solid States
Authors: Shinomiya Toshiomi
Published: July 2006

The dielectric constants and losses of cyclopentanol (CPEN), cyclohexanol (CHEX), cycloheptanol (CHEP), and cyclooctanol (COCT) have been measured at frequencies from 1.35 to 4500 MHz over a temperature range of 10–35°C. The absorption could be resolved into three Debye-like dispersion regions in liquid and solid states. The relaxation time of the first, low-frequency, dispersion region and viscosity for CHEX are slightly larger than those for CHEP. This observation can be connected with differences of the molecular geometry between a chair and a twisted chair form and an interconversion between an equatorial and an axial form. Upon solidification, the magnitude of the first dispersion region decreases from 12.67 in the liquid state to 10.25 in the solid state for CHEX and increases from 8.77 to 9.35 for COCT. A transformation from a linear chain polymer into a nonpolar cyclic polymer for CHEX and from a linear chain polymer into a chain dimer and trimer for COCT, occurs mainly upon solidification. The free energies of activation in the solid state are 26 kJ mol−1 for the first region, 23 kJ mol−1 for the second region, and 17 kJ mol−1 for the third region and are larger than those in the liquid state, respectively.
An Equilibrium Model of the Self-Association of 1- and 3-Pentanols in Heptane
Authors: Shinomiya Kazuko , Shinomiya Toshiomi
Published: July 2006

The near-IR spectra in the first overtone of the OH stretching vibrational range have been measured over all the alcohol concentrations from 0.002 mol dm−3 to neat pentanol at 25 and 35°C. The spectra were best fitted by a monomer–dimer model at concentrations below 0.025 mol dm−3, by a monomer–dimer–tetramer model in the concentration range of 0.025–0.35 mol dm−3, and by a monomer–dimer–tetramer–octamer model at concentrations above 0.35 mol dm−3. The dielectric constants and losses of pure 1- and 3-pentanols and heptane solutions of 1-decanol have been measured at frequencies from 1.35 to 4500 MHz at 15, 25, and 35°C. The dielectric absorption could be resolved into three Debye-like dispersion regions. The concentrations of a free monomer, a chain dimer and trimer, a linear chain polymer, and a nonpolar cyclic polymer have been obtained by applying a modified Kirkwood–Fröhlich equation. From a comparison of the near-IR results with the dielectric results, we can recognize at least the coexistence of a free monomer, a chain dimer, a nonpolar cyclic tetramer, and a linear chain octamer at higher concentrations of 1- and 3-pentanols in heptane at room temperature.
Dinuclear Cobalt(II) Complexes Containing 1,3-(or 1,5-)Bis[bis(2-pyridylmethyl)amino]-2-propanolato (or -3-pentanolato): Preparation and Reaction with Molecular Oxygen
Authors: Suzuki Masatatsu , Sugisawa Toshiharu , Uehara Akira
Published: July 2006

Two dinuclear cobalt(II,II) complexes, [Co2(tpdp)(CH3COO)](ClO4)2·0.5H2O (1) and [Co2(tmdp)(CH3COO)](ClO4)2·H2O (2), were prepared, where Htpdp and Htmdp are 1,3-bis[bis(2-pyridylmethyl)amino]-2-propanol and 1,5-bis[bis(2-pyridylmethyl)amino]-3-pentanol respectively. Their electronic spectral and magnetic data revealed that 1 and 2 are five-coordinate in the high-spin state, in the same manner as [Co2(bpmp)(CH3COO)]2+ (3) (Hbpmp=2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-methylphenol). The complexes reacted with molecular oxygen to form μ-peroxo complexes in dichloromethane and acetonitrile. The oxygen affinity of the complexes decreased in the order of 3>2>1. The relationships between the oxygen affinities and (1) the donor abilities of dinucleating ligands, (2) the energies of the charge-transfer bands (O22− to Co3+) of the μ-peroxo complexes, and (3) the redox potentials of the Co3+–O2−–Co3+/Co3+–O22−–Co3+ couple indicated that a steric effect arising from the dinucleating ligands contributes significantly to the oxygen affinities of the complexes.
Substituent Effects. XIX. Solvolysis of 1-Aryl-1-(trifluoromethyl)ethyl Tosylates
Authors: Murata Akihisa , Goto Mutsuo , Fujiyama Ryoji , Mishima Masaaki , Fujio Mizue , Tsuno Yuho
Published: July 2006

The rates of solvolysis of 1-aryl-1-(trifluoromethyl)ethyl tosylates were determined in 80% aqueous ethanol for a series of substituents. The Brown ρ+σ+ treatment fails to give a simple linear plot, but all the p-π-donors deviate upward from the meta-correlation line. On the other hand, the Yukawa–Tsuno LArSR Eq. gives a linear correlation over the whole range of substituents, log(k⁄k0)=−6.287(σ°+1.388Δ\barσR+), with excellent precision. Strong destabilization of the carbocation intermediate by α-CF3 appears to be reflected only in the extremely high r value, but not in the ρ value of the substituent effect. This conflicts seriously with the conclusion in the literature given for this reaction based on a simple Brown σ+ treatment. This reaction, having an extremely high resonance demand r=1.4, should be far beyond the scope of the simple Brown σ+ analysis. Varying resonance demand should be a basic requirement for adequately describing the substituent effect regarding conjugative carbocation reactions.