bluuebunny/crossref_metadata_2025 huggingface dataset:
The Crystal and Molecular Structure of an Isomer of Dibromoperylenes
Authors: Uchida Tokiko , Kozawa Kozo , Nagao Yukinori , Misonoo Takahisa
Published: July 2006

Of two isomers of dibromoperylene, the one possessing the higher melting point has been determined to be 3,9-dibromoperylene from the X-ray diffractometer data. The crystals are monoclinic, with a space group of P21/a, a=15.238, b=11.826, c=3.928 Å, β=95.53°, Dm=1.90, Dx=1.94 g cm−3, and Z=2. The structure was solved by the heavy-atom method. The final R value was 0.090 for 931 reflections.
Synthesis of a Protected Hexadecapeptide Corresponding to Positions 1–16 of Human Lysozyme
Authors: Yoshimura Shoko , Izumi Kunitatsu , Shimonishi Yasutsugu
Published: July 2006

For a semi-synthesis of human lysozyme by coupling its natural fragment with synthetic peptides, a protected hexadecapeptide corresponding to positions 1–16 of the enzyme was constructed from three protected peptide fragments (V, IX, and XII) by the conventional method in pure state on the basis of analyses.
Restricted Rotation Involving the Tetrahedral Carbon. XXV. Barriers to Exchange between dl and meso Forms of 9-(Arylmethyl)triptycenes
Authors: Kono Motomichi , Kihara Hiroshi , Nakamura Nobuo , Suzuki Fumio , \={O}ki Michinori
Published: July 2006

Barriers to exchange between dl and meso forms via rotation about the C9–Csubst bond of 9-(arylmethyl)-1,4-dimethoxytriptycenes are obtained by the use of the methoxyl signals in the 1H NMR spectra. It is found that, although the population ratios are affected by the substituent in the 9 position, the enthalpy of activation for the rotation is almost invariant at ca. 10 kcal/mol.
Structure of Alnustic Acid, a New Secodammarane-type Triterpenic Acid from Alnus sieboldiana
Authors: Suga Takayuki , Aoki Tadashi , Hirata Toshifumi , Aoki (née Sukemiya) Keiko , Asakawa Yoshinori
Published: July 2006

A novel C31 3,4-secodammarane-type triterpenoid, alnustic acid, was isolated from the male flowers of Alnus sieboldiana Matsum. (Betulaceae). Its structure was elucidated to be (12R,20S)-12,20-dihydroxy-24-methylene-3,4-secodammar-4(28)-en-3-oic acid by a combination of chemical and spectroscopic methods.
Synthesis of 8- and 10-Methyl-substituted 8,9,10,11-Tetrahydro-7H-cycloocta[de]naphthalenes and Their 9-Oxo Derivatives
Authors: Kamada Toshihiro
Published: July 2006

A novel and convenient method for the synthesis of the 8,9,10,11-tetrahydro-7H-cycloocta[de]naphthalene ring system is described. Reaction of diethyl acetonedicarboxylate and 1,8-bis(bromomethyl)naphthalene gave the eight-membered pericyclized compound, diethyl 9-oxo-8,9,10,11-tetrahydro-7H-cycloocta[de]naphthalene-8,10-dicarboxylate, which was then converted, through several steps, into various kinds of 8- and 10-methyl-substituted 8,9,10,11-tetrahydro-7H-cycloocta[de]naphthalenes and their 9-oxo derivatives, as well as the unsubstituted compounds, 8,9,10,11-tetrahydro-7H-cycloocta[de] naphthalene and 8,9,10,11-tetrahydro-7H-cycloocta[de]naphthalen-9-one. The hydrocarbon, 8,8,10,10-tetramethyl-8,9,10,11-tetrahydro-7H-cycloocta[de]-naphthalene was prepared from 8,8,10,10-tetrakis(tosyloxymethyl)-8,9,10,11-tetrahydro-7H-cycloocta[de]naphthalene.
Molecular Structure of 5β,6β-Isopropylidenedioxy-15,16,17-trinorgrrayan-10(20)-ene-3,14-dione as Revealed by X-Ray Methods
Authors: Furusaki Akio , Gasa Shinsei , Matsumoto Takeshi
Published: July 2006

The molecular structure of the title compound has been determined by means of the X-ray method. The A, B, and C rings take half-chair, chair, and chair conformations, respectively, while the heterocyclic ring is of envelope form.
Kinetics on the Formation and Transformation of Alkoxy-derived SrSiO3
Authors: Yamaguchi Osamu , Matsumoto Kenzo , Shimizu Kiyoshi
Published: July 2006

A metastable modification of SrSiO3 was formed at 850–910 °C from mixed powders prepared by the alkoxy-method. Crystallization isotherms were best described by the first-order equation and the activation energy was determined as 130 kcal/mol. The kinetics on the transformation of metastable to stable SrSiO3 was also studied.
Dynamic Calibration and Memory Effect for Fluoride Ion Selective Electrode
Authors: Umezawa Yoshio , Nagata Minoru , Sawatari Katsuhiko , Fujiwara Shizuo
Published: July 2006

The dynamic calibration of the F− ion selective electrode was briefly evaluated in terms of the memory effect of the electrode by analyzing the NBS urine standard.
Crystal Distortion and Cation Distribution in the System La1⁄3NbO3–WO3
Authors: Torii Yasuyoshi
Published: July 2006

It has been found that WO3 is soluble in La1⁄3NbO3 up to ca. 35 mol %. The solid solutions showed an ordered perovskite structure. The orthorhombic distortion changes into a tetragonal one at 20 mol%. The temperature dependence of the tetragonality of typical samples has been examined and the nature of the tetragonal distortion discussed.
Vibration Spectra and Rotational Isomerism of Chain Molecules. VIII. 1-Chloro-, 1-Bromo-, and 1-Iodopentanes, and 1,4-Dichloro- and 1,4-Dibromobutanes
Authors: Matsuura Hiroatsu , Imazeki Shuji , Ogawa Yoshiki , Sakakibara Masaaki , Harada Issei , Shimanouchi Takehiko
Published: July 2006

The Raman and infrared spectra of 1-chloro-, 1-bromo, and 1-iodopentanes CH3(CH2)4X (X=Cl, Br, and I), and 1,4-dichloro- and 1,4-dibromobutanes X(CH2)4X (X=Cl and Br) were measured for the gaseous, liquid, glassy, and crystalline states. The normal coordinates were calculated for these molecules by the use of a consistent set of force constants. The rotational isomerism was studied by analyzing the spectra with reference to the results of the calculation. The study clarified the isomers present not only in the crystalline state but also in other states of aggregation. In the crystal, 1-chloro-, 1-bromo-, and 1-iodopentanes take the trans-trans-trans form and 1,4-dichloro- and 1,4-dibromobutanes take the gauche-trans-gauché form.
Synthesis of 4,8-Dimethyl-5,7-nonamethyleneazulene
Authors: Kurokawa Shinji , Anderson Arthur G
Published: July 2006

The title compound has been prepared from 2,6-dimethyl-3,5-nonamethylenepyrylium perchlorate and from 1,2,6-trimethyl-3,5-nonamethylenepyridinium iodide in low yield by reaction with sodium cyclopentadienide. The UV, visible and PMR spectra of the title compound are correlated with the structure.
Reaction of Diazonium Salts with Transition Metals. II. Palladiumcatalyzed Arylation of Ethylene with Arenediazonium Salts
Authors: Kikukawa Kiyoshi , Nagira Kazuhiko , Terao Nobuyuki , Wada Fumio , Matsuda Tsutomu
Published: July 2006

Arylation of ethylene (7 atm) was carried out with various arenediazonium tetrafluoroborates (25 mmol) in the presence of bis(dibenzylideneacetone)palladium (0.5 mmol) and sodium acetate (75 mmol). Substituted styrenes were obtained in good yields (61–78%) under mild reaction conditions (1 h, room temperature) in a 1:1 mixture of acetone and dichloromethane, with some exceptions. Phenylbutenes, main by-products in dichloromethane, were presumed to form by the reaction of styrene with ethylene under catalysis of hydridopalladium species.
Diazotization of Aromatic Primary Amines of Weak Basicity. II. Reduction of Arenediazonium Salts with Alkylbenzene Derivatives
Authors: Takagishi Ikuo , Hashida Yoji , Matsui Kohji
Published: July 2006

The diazonio group of arenediazonium salts derived from weakly basic amines were efficiently substituted by hydrogen with alkylbenzenes in sulfuric acid. Several types of evidence, including kinetic results and experiments to trap an intermediate, indicated that the reduction occurs via an aryl radical intermediate. In the reduction with toluene, analyses of by-products suggested a radical chain mechanism, which would involve a propagation cycle caused by electron transfer from the benzyl radical to the diazonio group.
Carbon-13 Chemical Shifts of Retinal Isomers and Their Schiff Bases as Models of Visual Chromophores
Authors: Inoue Yoshio , Tokitô Yasuo , Tomonoh Shigeki , Chûjô Riichiro
Published: July 2006

Carbon-13 NMR spectra have been observed for 11- and 13-cis-retinals and their Schiff base linkage compounds with butylamine as a model compound of visual chromophore. The chemical shift changes on going from retinal to Schiff base. The changes in chemical shifts of polyene carbons were discussed in correlation with the changes of π-electron densities.
The Selective Elimination of Secondary Alkyl Group from Trialkylborane by the Successive Treatments with Anisole and Dimethyl Sulfoxide. A Supply of the Synthetic Intermediate for Primary Alkyl Derivatives
Authors: Masuda Yuzuru , Hoshi Masayuki , Arase Akira
Published: July 2006

Secondary alkyl group of trialkylborane, derived from terminal olefin and borane, was selectively eliminated by the successive treatments with anisole and dimethyl sulfoxide. By the use of the resulting trialkylborane as the synthetic intermediate for primary alkyl derivatives, the contaminations of secondary alkyl derivatives were greatly reduced.
A Synthetic Route to 5-Aryl-2-oxazolidinone Derivatives
Authors: Tsujimoto Yuji , Kosaka Atsushi , Hayashi Mitsunori , Miyamoto Takuji , Odaira Yoshinobu
Published: July 2006

5-Aryl-2-oxazolidinones have been synthesized readily by the elimination of dimethylamine from the corresponding (2-hydroxyethyl)ureas. The ureas are obtainable by the photoreaction of tetramethylurea with para-substituted benzaldehydes (Method A) or with para-substituted methyl benzoates (Method B). The electronic character of the substituent on the benzene ring determines which method is suitable for the preparation of (2-hydroxyethyl)ureas.
A Stereoselective Total Synthesis of Methyl α-Dl-Daunosaminide
Authors: Iwataki Isao , Nakamura Yasuo , Takahashi Koji , Matsumoto Takeshi
Published: July 2006

Starting from crotonoyl chloride, methyl α-Dl-daunosaminide was synthesized through the cis hydroxylation of a key intermediate, 1,1-ethylenedioxy-4-hexen-3-one, followed by oximation, catalytic hydrogenation (Pt, AcOH), and treatment with MeOH/HCl.
Kinetics of Reaction of 4-Substituted ω-Bromo-1-acetonaphthones with Aniline in Methanol
Authors: Nadar P Ananthakrishna , Gnanasekaran C
Published: July 2006

Rate constants have been measured for the reactions of 4-substituted ω-bromo-1-acetonaphthones with aniline in methanol at three temperatures. Arrhenius parameters, the enthalpies and the entropies of activation have been evaluated. The Hammett ρ value of 0.90 obtained at 40 °C indicates that a triangular transition state is more likely in this reaction.
Nitrogen 14 Nuclear Quadrupole Resonance Study of Several Condensed Ring Compounds
Authors: Hiyama Yukio , Maruizumi Takuya , Niki Eiji
Published: July 2006

The 14N nuclear quadrupole resonance spectra of 2-mercaptobenzothiazole, isatin(1H-indole-2,3-dione), and isatoic anhydride(2H-3,1-benzoxazine-2,4(1H)-dione) have been observed at room temperature by the nuclear double resonance method. The quadrupole coupling constants and the asymmetry parameters thus obtained were interpreted by the Townes and Dailey theory.
Photooxygenation Product of Dibenzo[a,j]perylene
Authors: Kajiwara Takashi , Fujisawa Shoji , Ohno Koichi , Harada Yoshiya
Published: July 2006

The photooxygenation of dibenzo[a,j]perylene by visible light irradiation was studied spectroscopically. The structure of unstable photooxygenation product was deduced from spectroscopic data and results of MO calculations to be as 8,12b-endoperoxide of dibenzo[a,j]perylene. This endoperoxide released oxygen gradually at room temperature, recovering the original hydrocarbon. The activation energy for this dark reaction was determined to be 21.4±0.5 kcal/mol in benzene and 22.6±0.5 kcal/mol in ethanol.
Ultrasonic Velocity and Compressibility in Aqueous Solutions of Alkali Metal Chlorides
Authors: Uedaira Hisashi , Suzuki Yasuko
Published: July 2006

The ultrasonic velocity of aqueous solutions of alkali metal chlorides was measured by the use of the singaround technique at 0.5 and 1 mol kg−1 over the temperature range from 30 to 85 °C; compressibilities of the solutions were also determined. It was found that the ultrasound velocity versus temperature curves show a maximum, while the compressibility versus temperature ones show a minimum. Both maxima and minima appear at lower temperatures than that observed for pure water. The maximum shifted values were found for Na+ ion. The results were explained by the dynamic structure of the water around the ions.
Effect of Pressure on Iodine Complexes. I. Absorption Spectra of the Visible Iodine Bands with Diethyl Ether, Diethyl Sulfide, and Diethyl Selenide in Heptane
Authors: Sawamura Seiji , Taniguchi Yoshihiro , Suzuki Keizo
Published: July 2006

Absorption spectra of the visible I2 band of I2 complexes with Et2O, Et2S, and Et2Se in heptane have been measured up to 3300 bar at 25 °C. The equilibrium constants and volume changes accompanying complex formation, the molar extinction coefficients and the absorption maxima have been estimated. The volume changes were found comparable with those estimated from the X-ray data of the I2 complexes in the crystalline state. The enhancement of the molar extinction coefficient and the blue shift of the visible I2 band with increasing pressure have been established. The results suggest a decrease in the bond distance between an n-donor and I2, compared with the spectroscopic properties of the I2 complex at 1 bar. The decrease has been estimated as 0.008 nm with increasing pressure up to 3300 bar.
Vibrational Spectra and Normal Coordinate Calculations for Methyl-1-propynylmercury(II) and Its Deuterated Analogues
Authors: Imai Yoshika , Aida Koyo
Published: July 2006

Infrared spectra (4000–80 cm−1) of CH3HgC≡CCH3, CD3HgC≡CCH3, CH3HgC≡CCD3, and CD3HgC≡CCD3 have been obtained in carbon tetrachloride, carbon disulfide and benzene solutions, as well as in the solid state at liquid nitrogen temperature. Raman spectra (4000–0 cm−1) have also been recorded on benzene solutions and on solids at room temperature. Assignments for all the fundamentals have been made assuming C3v molecular symmetry. Normal coordinate calculations have been carried out in order to confirm the proposed assignments.
Phase Transformation of Iron Vanadium Sulfides at High Temperatures
Authors: Wada Hiroaki
Published: July 2006

The phase relations of iron vanadium sulfides with the atomic Fe: V ratios 3 : 2 and 71 : 29 were examined by the high-temperature DTA and X-ray measurements. It was found that the structure of iron vanadium sulfide changes gradually from a less symmetric form to a highly symmetric form with the increase in temperature. Two types of phase transformations by vacancy order-disorder were observed at temperatures above 800 °C. One was due to the intralayer disordering of metal vacancies: V3S4-type→Cd(OH)2-type (type Ia) or V3S4-type+NiAs-type→Cd(OH)2-type (type Ib) at T1. The other was due to the entirely interlayer disordering of metal vacancies: Cd(OH)2-type→NiAs-type (type II) at T2 (T2>T1). The tentative phase diagram of iron vanadium sulfides with the atomic Fe: V ratio 3 : 2 was constructed on the basis of the DTA results.
Distribution of Alkylboranes in the Reaction of Norbornene and Cyclopentene with Borane–THF
Authors: Taniguchi Hiroaki
Published: July 2006

Systematic studies of the partial alkylation of diborane with norbornene and cyclopentene were carried out in THF and the equilibrium distribution of the borane derivatives was determined. Di-exo-norbornylborane was obtained in 71% yield with no mono-exo-norbornylborane as a by-product, under the conditions: initial ratio of norbornene to borane 2 : 1, temperature 0 °C and reaction time 1 h. Mono-exo-norbornylborane was obtained in 72–75% yield under the conditions: initial ratio of norbornene to borane 1 : 1, temperature 25 °C, and reaction time 48 h. In the dialkylborane [R2BH]2, norbornene and cyclopentene exhibit very different behavior during the course of equilibration reaction.
Sodium Methoxide Catalyzed Isomerization of Dimethyl 1-Oxo-cis-3a,7a-dihydroindene-3a,7a-dicarboxylates to Dimethyl 3-Oxo-1,7-indandicarboxylates
Authors: Uyehara Tadao , Miyakoshi Shoichi , Kitahara Yoshio
Published: July 2006

Treatment of dimethyl 1-oxo-cis-3a,7a-dihydroindene-3a,7a-dicarboxylates (A) with sodium methoxide in methanol gave particular dimethyl 3-oxo-1,7-indandicarboxylates (F). A multistep mechanism for the isomerization was proposed on the basis of the positional correlations between the dihydroindenones A and the corresponding isomers F. The isomerization seems to be initiated by the addition of a methoxide to the 1 position of the dihydroindenones A affording the cyclohexadienide anions (B), which cyclize to give dimethyl 1-oxo-cis-3a,7a-dihydroindene-3a,4-dicarboxylates (C). The dihydroindenones C become enolates (D), whose methoxycarbonyl group at the 3a position (E9) shifts to the 1 position of the enolates of F, (E), with the aid of aromatization. The same treatment of methyl 3-oxo-cis-3a,7a-dihydroindene-3a-carboxylates gave key information on the process for the isomerization of A.
Modifizierte Wichterle-Reaktion. Ein Weg zur Darstellung von 2-Cyclohexenonen und 1,4-Diketonen. Synthese von 4-Estren-3,17-dion und Dihydrojasmon
Authors: Kobayashi Makoto , Matsumoto Takeshi
Published: July 2006

Während die Behandlung von 2-(3-Chlor-2-butenyl)-2-methylcyclohexanon mit konz. H2SO4 2,5-Dimethylbicyclo[3.3.1]non-2-en-9-on als Hauptprodukt ergab, wurde beim Erhitzen in HCO2H in Anwesenheit von HClO44a-Methyl-Δ1(8a)-2-octalon in 70 bis 98%-iger Ausbeute erhalten. Unter diesen Bedingungen reagierten andere α(Chlorbutenyl)ketone analog und lieferten die entsprechende Annelierungsprodukte in hohen bis mässigen Ausbeuten. Aus α-(2-Haloallyl)ketonen wurden 1,4-Diketone gewonnen. Als Anwendungsbeispiele wurden 4-Estren-3,17-dion und Dihydrojasmon synthetisiert.
Conformational Equilibria of 8-Alkyl-8,9,10,11-tetrahydro-7H-cycloocta[de]naphthalenes
Authors: Kamada Toshihiro , Yamamoto Osamu
Published: July 2006

The conformations of 8-methyl (4) and 8-ethyl-8,9,10,11-tetrahydro-7H-cycloocta[de]naphthalenes (5) have been studied on the basis of the NMR spectra. It was found that both compounds exist as an equilibrium mixture of the axial-boat (ab) and the equatorial-boat (eb) conformers in solution. The 1H spectra revealed that the boat conformations of all these isomers are somewhat in the distorted form due to the steric repulsion between the interior benzyl protons. The free-energy differences (−ΔG°) between the two isomers (ab\ightleftarrowseb) in 4 and 5 were calculated from the 13C spectra and found to be 0.09 and −0.07 kcal/mol, respectively. These results are discussed in terms of the structural and conformational features of the 8-membered pericyclized naphthalene ring and compared with the cyclohexane ring.
Catalytic Efficiency of Synthetic Micellar Catalysts Bearing a Mercapto Group as the Reaction Center
Authors: Murakami Yukito , Nakano Akio , Matsumoto Kiyoshi
Published: July 2006

In order to obtain a clue to understanding the micro-environmental effect on the reactivity of a mercapto group placed in a reaction center of enzymes, micellar surfactants bearing a mercapto group were synthesized and their catalytic activity in the degradation of p-nitrophenyl carboxylates was studied. N-Hexadecyl-Nα-glutaryl-l-cysteinamide (AM·Cys-1) has an ability to form anionic micelles in aqueous media. The catalytic activity of AM·-Cys-1 was compared with that of another synthetic surfactant, N-hexadecanoyl-l-cysteine (AM·Cys-2). These surfactants below their critical micelle concentrations markedly accelerated the degradation of several p-nitrophenyl carboxylates. On the contrary, the concentration - rate profiles for the degradation of p-nitrophenyl dodecanoate (PNPL) as catalyzed by the surfactants indicate that the reactivity of the mercapto group is reduced upon formation of the anionic micelles. The large rate retardation is primarily due to the decrease in concentration of the active thiolate anion. This was supported by the fact that the pKa values for mercapto groups of the anionic micelles, for which the carboxyl group acts as an anionic head, were increased by 0.8–1.6 pKa unit over those of the corresponding monomeric surfactants in the bulk phase. These surfactants showed profound reactivity even in a neutral pH region when mixed with cationic CTAB micelle. The electrostatic field effect provided by the cationic head of CTAB micelle seems to enhance the nucleophilicity of the mercapto group in the mixed micelles.
The Hydrocracking of Solvent Refined Coals over Molten Salt Catalysts
Authors: Nakatsuji Yohji , Ikkaku Yasuhiko , Nomura Masakatsu , Kikkawa Sh\={o}ichi
Published: July 2006

The hydrocracking of Y\barubari SRC and Tempoku SRC over ZnCl2/CuCl or ZnCl2 molten salt was examined at 350 or 400 °C for 3 h in a batch autoclave system. The reactivity of SRC under the hydrocracking conditions with the molten salts was estimated mainly by comparison with the results obtained in the study using a variety of polynuclear aromatic hydrocarbons. The presence of hetero atoms (especially, the hydroxyl group) in SRC may be supposed to play an important role in this hydrocracking using molten salts. In addition, the average structures of SRC, according to the GAMSG method, are offered, and the usefulness is examined from the point of view of the reactivity of SRC in the presence of molten salts.
NQR and NMR Studies of Boron Trihalide–Trimethylamine Complexes
Authors: Okuda Tsutomu , Ishihara Hideta , Yamada Koji , Negita Hisao
Published: July 2006

The character of the B–X bond (X=Cl, Br, and I) in BX3–TMA complexes (TMA=trimethylamine) has been studied on the basis of the results of the nuclear quadrupole resonance (NQR). The ionic character of the B–X bond decreased in the order as expected from the electronegativity of the halogen atoms. The temperature dependence of the halogens on the NQR frequencies has been examined for BBr3– and BI3–TMA. For BBr3–TMA, all the observed resonance lines faded out far below the melting point and this has been attributed to the hindered rotation of the BBr3 group about the B–N bond, as with BCl3–TMA.
Oxidation of Benzaldehydes by Peroxomonophosphoric Acid. A Kinetic and Mechanistic Study in Acid and Alkaline Media
Authors: Panigrahi G P , Panda Radhasyam
Published: July 2006

The oxidation of benzaldehydes by peroxomonophosphoric acid has been found to proceed by

(i) −d[peroxomonophosphoric acid]⁄dt∝ [benzaldehyde][peroxomonophosphoric acid][H+]x

where x=a fraction at [H+]<0.5 M and x=0 at [H+]>0.5 M and

(ii) −d[peroxomonophosphate]⁄dt∝ [benzaldehyde][peroxomonophosphate][OH−]y

where y=a fraction at [OH−]<0.1 M and y=0 at [OH−]>0.1 M.

In the alkaline oxidation Hammett relationship is obeyed excellently, unlike the oxidation in the acid medium. The oxidation mechanisms are discussed in terms of a nucleophilic attack of the peroxomonophosphoric acid species on the carbonyl carbon centre. Thermodynamic parameters have been evaluated to substantiate the mechanisms.
Phase Transition of [(C6H5)3PCH3]1−x+ [(C6H5)3AsCH3]x+ (TCNQ)2\ewdot, (0≤x≤1), Anion Radical Salts. Thermodynamical Stability of the Solid Solutions
Authors: Iida Yôichi
Published: July 2006

The phase transition and the thermodynamic properties of solid solutions were studied with anion radical salts of [(C6H5)3PCH3]1−x+ [(C6H5)3AsCH3]x+ (TCNQ)2\ewdot, (0≤x≤1). The stability condition of the solid solutions was examined in both the low- and high-temperature phases.
Proton Magnetic Relaxation Study of Oxalic Acid Dihydrate
Authors: Chiba Takehiko
Published: July 2006

Proton magnetic relaxation times T1, T1ρ, and T1D were measured on a single crystal of α-form oxalic acid dihydrate in two modes: temperature dependence at one or two specific crystal orientations, and angular dependence at several temperatures. Results were compared with the calculation based on an isolated three proton system for the assumed modes of motions. The temperature dependence of T1 and that of T1ρ and T1D in the low temperature range are reasonably accounted for by the 180°-flip of the water molecule. The activation energy for the motion of 43.6 kJ mol−1 is obtained. T1ρ and T1D above about 35 °C decreased as the temperature was raised. The comparison of the observed results in this temperature range with the calculated ones suggests that there is exchange motion among the three spins. An activation energy for this motion of 80.8 kj mol−1 is obtained. This three spin exchange motion may be considered as a combination of a jump of carboxyl proton to a higher potential trough corresponding to the ionic configuration and the three-fold reorientation of the hydronium ion thus formed.
The Synthesis of Crystalline Zirconium Phosphate with Large Particle Size by the Direct-precipitation Method
Authors: Inoue Yasushi , Yamada Yoshimune
Published: July 2006

The direct-precipitation method was studied as a possible way to synthesize crystalline zirconium phosphate of a large and uniform crystal size. The yield and the crystal size were examined as functions of the initial hydrofluoric-acid and phosphoric-acid concentrations and the warming temperature. The conditions for preparing the largest crystal were: ZrOCl2·8H2O, 0.13 M; hydrofluoric acid concentration, 0.715 M; phosphoric acid concentration, 5 M; temperature, 50 °C. Those for preparing the material with uniform crystal-size distribution and a possibly large-mean crystal size were: ZrOCl2·8H2O, 0.13 M; hydrofluoric acid concentration, 0.715 M; phosphoric acid concentration, 9 M; temperature, 60 °C. The product was confirmed to be crystalline Zr(HPO4)2·H2O by means of chemical, thermal, and X-ray analyses, and by an examination of the titration curve.
Thermodynamic Studies on Phase Transitions of Potassium Thiocyanate and Ammonium Thiocyanate Crystals
Authors: Kinsho Yoshio , Onodera Natsuo , Sakiyama Minoru , Seki Syûzô
Published: July 2006

Heat capacities of KSCN and NH4SCN crystals were measured by adiabatic calorimetry in the temperature range between 13 K and the melting points. Molar volume of NH4SCN was also determined above room temperature. Entropy change for the II-I transition of KSCN (414.54 K, essentially higher order but accompanied with the first order component) is 6.26 J K−1 mol−1 (=1.09 R In 2), which is of similar magnitude with our previous value (Bull. Chem. Soc. Jpn., 36, 1025 (1963)). Entropy change for the III-II transition of NH4SCN (360.1 K,first order) is 10.01 J K−1 mol−1 and apparent entropy change for the II-I transition of NH4SCN (392.8 K, higher order) is 2.85 J K−1 mol−1 (=0.49 R In 2) in spite of possibly similar nature of the transition with the II-I transition of KSCN. A possibility has been suggested that the entropy change might be approximately R In 2 if the transition was not interfered with the III-II trasition and the premelting.
A Study of the Ligand Exchange Reaction of Tetrakis(μ-trifluoroacetato)dimolybdenum(II) in Acetonitrile by 19F NMR Spectroscopy
Authors: Teramoto Kazunori , Sasaki Yoichi , Migita Kouto , Iwaizumi Masamoto , Saito Kazuo
Published: July 2006

The dimeric molybdenum(II) complex, Mo2(CF3COO)4, forms Mo2(CF3COO)4·(CH3CN)2 in acetonitrile, where solvent molecules are attached to positions trans to the metal–metal bond (apical positions). The rate of ligand exchange between Mo2(CF3COO)4 ((1.31–8.28)×10−2 M; M=mol dm−3) and CF3COONa ((1.31–4.56)×10−1 M) was measured in acetonitrile by the use of 19F NMR spectroscopy. The rate is independent of the total concentration of CF3COONa and is linearly dependent on that of Mo2(CF3COO)4. The first-order rate constant (kex) is (1.1±0.2)×104 s−1 (25 °C), and the activation parameters are ΔH\eweq=(8.2±0.8) kcal mol−1 and ΔS\eweq=(−15±3) K−1 mol−1. Under the given conditions the complex seems to exist as Mo2(CF3COO)4·CF3COO−, where the underlined ligand occupies one of the apical positions, and the following mechanism is proposed (solvent molecules are omitted; asterisks indicate the molecule substituting for the coordinated ligand).

Mo2(CF3COO)4·CF3COO−+*CF3COO−\oversetfast\ightleftarrowsMo2(CF3COO)4·*CF3COO−+CF3COO−

Mo2(CF3COO)4·*CF3COO−\oversetks→Mo2(CF3COO)3(*CF3COO)·CF3COO−

The kex corresponds to ks.
Thermal Decomposition of Coal-related Aromatic Compounds in Hydrogen-donating Solvent
Authors: Yao Tadashi , Kamiya Yoshio
Published: July 2006

In order to elucidate the reaction mechanism of coal dissolution in the hydrogen-donating solvent, twenty aromatic compounds related to coal were treated at 450 °C in the presence of tetralin. Diphenylmethane and bibenzyl slowly decomposed giving alkylbenzenes almost quantitatively. Diphenylmethanol and benzophenone were hydrogenated to diphenylmethane, and benzyl phenyl ketone to a mixture of diphenylmethane and bibenzyl. Diphenyl ether and dibenzofuran are very stable, di-2-naphthyl ether decomposing slowly and benzyl phenyl ether or dibenzyl ether very rapidly. The conversion of aromatic compounds by thermolysis can be correlated as a function of bond dissociation energy. The bond rupture of coal-related polynuclear aromatic compounds at 450 °C was concluded to occur mainly at methylene or ether structures. Addition of phenolic compounds or quinoline is very effective for the decomposition of di-2-naphthyl ether. The effect of phenolic compounds and quinoline on the thermal decomposition of aromatic ether was discussed on the basis of stabilization of transition state due to solvation.
Spectroscopic Studies of Solvent Effects on Intramolecular Hydrogen Bonding in N-Substituted Salicylamides
Authors: Kondo Michio
Published: July 2006

It has been found from absorption and emission spectra that the intramolecular hydrogen bonds between the phenolic hydroxyl and carbonyl group of N-methylsalicylamide and N-methyl-5-chlorosalicylamide survive in DMSO as well as in 1,2-dichloroethane, whereas those of N,N-dimethylsalicylamide and N,N-dimethyl-5-chlorosalicylamide are disrupted in DMSO. The solvent dependence of the 1H and 13C chemical shifts of these compounds are also well related to the intramolecular hydrogen bonding.
Light-induced Conformational Changes of Polypeptides. Photoisomerization of Azoaromatic Polypeptides
Authors: Ueno Akihiko , Anzai Jun-ichi , Osa Tetsuo , Kadoma Yoshinori
Published: July 2006

Copolymers of β-benzyl l-aspartate with β-m- or p-(phenylazo)benzyl l-aspartate were prepared in order to investigate the effect of side-chain photoisomerization on their conformations. These polymers in 1,2-dichloroethane show a CD band at 222 nm characteristic of left-handed α-helices. After irradiation, remarkable changes of the 222 nm band were observed for both meta and para copolymers with more than 50 % azo residues. The decrease in ellipticity observed for the meta copolymers indicates that photoisomerization induces a significant instability in the left-handed α-helical conformation. On the other hand, the para copolymers change their sign from positive to negative by irradiation, confirming the reversal in the helix sense. In the course of subsequent relaxation of the irradiated para copolymer with 59% azo residues, an abrupt change in the CD spectra was found above 50% cis followed by a gradual change on decreasing the content of cis isomers. Concerning the polymers with azoaromatic side chains including copolymers with γ-benzyl l-glutamate, the helical sense seems to affect appreciably the sign of the side-chain CD bands.
Photochemical Thiocyanation of Halobenzenes with Thiocyanate Anion
Authors: Fujiki Kiyoko , Nishio Takehiko , Omote Yoshimori
Published: July 2006

Halobenzenes having such an electrondonating group as amino, hydroxyl or methoxyl group at their para position were thiocyanated with sodium thiocyanate under irradiation. Also, the ring isomer of o-thiocyanatoaniline, 2-aminobenzothiazole, was obtained by the photoreaction of o-chloroaniline with sodium thiocyanate.
Oxidation of Organic Compounds with Perborates or H2O2–Boric Acids
Authors: Ogata Yoshiro , Shimizu Hideo
Published: July 2006

Perborate oxidation of p-chloroaniline to 4,4′-dichloroazobenzene and H2O2–boric acid hydroxylation of aromatics have been studied. The kinetic behavior suggests that the so-called sodium perborate is not peroxoborate but borate peroxyhydrate, H2O2 acquiring stronger electrophilicity by the coordination with boric acid which acts as Lewis acid rather than protic acid.
The Reaction of 1-(1-Pyrrolidinyl)acenaphthylene with Electrophilic Acetylenes
Authors: Tsuge Otohiko , Watanabe Haruyuki
Published: July 2006

1-(1-Pyrrolidinyl) acenaphthyIene (1), which was prepared from acenaphthenone and pyrrolidine, reacted with dimethyl acetylenedicarboxylate to give the dihydrocyclohepta[de]naphthalene and dihydrofluoranthene. The reaction of 1 with methyl propiolate in benzene afforded the dihydrocyclohepta[de] naphthalene (8) and its isomeric cyclohepta[denaphthalenol (9), whereas the Michael type adduct was formed in methanol. An interconversion between 8 and 9 was also described.
A Novel Synthesis of δ-Amino Acid Derivatives
Authors: Imagawa Takeshi , Kawanisi Mituyosi
Published: July 2006

The Diels-Alder adducts of “anhydrochloral-urethane” with some 1,3-dienes were successfully utilized for the synthesis of some δ-amino acid derivatives by the sequence of the reactions, viz., hydrogenation, dehydrochlorination, and ozonolysis.
Absorption and Fluorescence Spectra of Anthracenecarboxylic Acids. II. 1- and 2-Anthroic Acids
Authors: Suzuki Satoshi , Fujii Tsuneo , Yamanaka Shigeru , Yoshiike Nobuyuki , Hayashi Zenro
Published: July 2006

The absorption and fluorescence spectra of 1- and 2-anthroic acids (1- and 2-anthracenecarboxylic acids) in alcoholic solvents have been observed as a function of solute concentration. It was revealed that 1- and 2-anthroic acids form hydrogen-bonded dimers in their ground states. The equilibrium constants for dimer formation are : 1.2×104 mol−11 for 1-anthroic acid in methanol and 2.0×104 mol−11 for 2-anthroic acid in ethanol. Owing to dimer formation, the lowest frequency absorption band of 1-anthroic acid was uniformly displaced to the red, while that of 2-anthroic acid was distinctly resolved into two bands. The band assignment was confirmed by the method of photoselection. No excimer-type fluorescence was observed in 1- and 2-anthroic acids. The lack of mirror-symmetry relationship between the absorption and fluorescence spectra of 1-anthroic acid is explained by the geometrical relaxation in its excited state.
Thermochromism of Metal Chelates with Triphenylmethane Complexons in Aqueous Solutions. I. Copper(II)–Xylenol Orange System
Authors: Nakada Shoji , Yamada Mutsuo , Ito Tasuku , Fujimoto Masatoshi
Published: July 2006

Reversible thermochromisms are found for about thirty kinds of metal complexes of triphenylmethane complexons in aqueous solutions. The thermochromism observed in the aqueous solution of copper(II) complex with 3,3′-bis[N,N-bis(carboxymethyl)aminomethyl]-o-cresolsulfonphthalein (Xylenol Orange, XO) was primarily ascribed to the temperature-dependence of the protolytic equilibria between a complex species AH having an uncoordinated free phenolic hydroxyl group and a complex species A having a coordinated phenolate group: AH\ightleftharpoonsA+H. The equilibrium constant K of the reaction was determined to be p(K/mol dm−3)=4.40 at 25 °C. The thermodynamic parameters ΔH and ΔS for the reaction were calculated to be 26±2 kJ mol−1 and 1±3 J mol−1 K−1 (298 K), respectively. The rate constant of the proton dissociation of the phenolic hydroxyl group in the complex AH was estimated to be ca. 2±105s−1.
Metal Complexes of Amino Acids. XI. Preparation and 13C NMR Spectra of the Cobalt(III) Complexes Containing β-Alanine and Glycine
Authors: Ama Tomoharu , Yasui Takaji
Published: July 2006

A series of complexes or geometrical isomers, [Co(β-ala or gly)(en)2]2+, [Co(β-ala or gly)2(en)]+, [Co(β-ala or gly)(ox)2]2−, and [Co(β-ala or gly)2(ox)]−, were prepared and their 13C NMR spectra were measured. Assignments of their structures and 13C NMR signals were made. The β-alaninate carbons in the complexes resonate at 33.6±0.5, 38.3±0.6, and 183.0±1.5 ppm and the glycinate carbons at 46.3±1.3 and 187.4±1.4 ppm. The 13C chemical shifts of the mixed (β-alaninato)(glycinato) complexes consist of those of the corresponding isomers of bis(β-alaninato) and bis(glycinato) complexes.
Luminescence Spectra of Cobalt(III) Cyano Complexes
Authors: Yamamoto Yusuke
Published: July 2006

Luminescence spectra of M3[Co(CN)6] (M=K, Rb, Cs), cis-K3Na2[Co(CN)4(SO3)2], and trans-Na5[Co(CN)4(SO3)2] were measured at 20 K. Single crystal luminescence spectra of the hexacyanocobaltates(III), centered at 14100–14200 cm−1, exhibited vibrational structure associated with three components, and the separation between the members of the progression was about 400 cm−1. Luminescence spectra of powdered cis-K3Na2[Co(CN)4(SO3)2] and trans-Na5[Co(CN)4(SO3)2] were structureless and broad centered at 13200 and 14400 cm−1, respectively. Comparison of these luminescence spectra with the corresponding spin-forbidden bands indicated that the 0-0 transition lies at 18300–18600 cm−1 for hexacyanocobaltates(III), at 16500–17000 cm−1 for cis-K3Na2[Co(CN)4(SO3)2], and at 17700–18200 cm−1 for trans-Na5[Co(CN)4(SO3)2]. The vibrational structure in luminescence spectra of hexacyanocobaltates(III) can be interpreted in terms of the ν8,ν9,ν12 and ν13 ungerade skeletal modes, a lattice mode, and the totally symmetric ν2 vibrational mode. Analysis of the relative intensity of the vibrational structure in the luminescence spectra gave information about the change in the Co–C internuclear equilibrium distance from the ground state to the excited luminescent state. The relationship between luminescence and photochemical behavior of cobalt(III) complexes was also considered.
The Relative Rate Constants of Reactions of Oxygen Atoms with Several Olefins in Liquid Carbon Dioxide
Authors: Karasawa Hidetoshi , Sasamoto Tai , Yugeta Rei , Sato Shin
Published: July 2006

The relative rate constants of reactions of oxygen atoms with several olefins and 2-methylpropane have been determined in liquid carbon dioxide at −18 °C, using the γ-radiolysis of carbon dioxide in the presence of these hydrocarbons. They are : 1-butene, 1.0; cis-2-butene, 2.3; trans-2-butene, 3.0; 2-methylpropene, 2.9; 2,3-dimethyl-2-butene, 2.0; 2-methylpropane, 0.07. These relative values are very different from those obtained in the gas phase. A possible reason is discussed and a simple theoretical treatment is proposed for the competition between diffusion and reaction on the basis of the idea of a “collision set” in the liquid phase. The reaction of oxygen atoms with paraffin in liquid carbon dioxide seems to be faster than that in the gas phase. The reason is not clear at present.
Formation of Micelles of Hexadecyltrimethylammonium Bromide in Water-N,N-Dimethylformamide Solutions
Authors: Ionescu Lavinel G , Tokuhiro Tadashi , Czerniawski Benjamin J
Published: July 2006

The critical micellar concentration of aqueous solutions of hexadecyltrimethylammonium bromide (HTAB) containing various amounts of N,N-dimethylformamide (DMF) has been determined at 25 and 40 °C by means of surface tensiometric measurements. The standard free energy (ΔGm°), enthalpy (ΔHm°) and entropy (ΔSm°) of micellization were also determined. The experimental results indicate that: (1) micelle formation is somewhat hindered by a raise in temperature, and (2) DMF has an inhibitory effect on the formation of micelles of HTAB. This effect is relatively small at low DMF concentrations, but it increases drastically as the mole fraction of DMF approaches 0.33. The changes in the ΔGm°, ΔHm°, and ΔSm° values indicate that the formation of HTAB micelles in the water-DMF mixtures is an entropy directed process at lower concentrations of DMF and the inhibitory effect of DMF on micelle formation is attributed to an increase in the orderliness of this system with increasing DMF concentration.
The Modified Wurtz Reaction Using Tetrakis(p-dimethylaminophenyl)ethylene
Authors: Miyahara Yuji , Shiraishi Takanari , Inazu Takahiko , Yoshino Tamotsu
Published: July 2006

The Wurtz reaction has been found to be catalyzed by easily removable tetrakis(p-dimethylaminophenyl)ethylene. This modification facilitated the separation of products in the syntheses of [2.1.2.1.]-, [2.2.2.2]-, and [3.2.3.2]paracyclophanes, the isolated yields of which were better than in the case of tetraphenylethylene.
Photochemical Formation of Tetrahydro-2-furyl Ether in Alcohol-Tetrahydrofuran-Iron(III) Chloride System
Authors: Kurokawa Hideo , Ishigami Tatsuzo , Morimoto Katsuaki , Sugimori Akira
Published: July 2006

Primary and secondary alcohols are converted into the corresponding tetrahydro-2-furyl ethers upon UV- and solar irradiation of alcohol and tetrahydrofuran in the presence of iron(III) chloride.
Synthetic Photochemistry. XIII. Chiroptical Retention for the Reported “antara-antara”-3,3-Sigmatropy of Bicyclo[3.2.0]hepta-3,6-dien-2-ones
Authors: Takeshita Hitoshi , Kumamoto Masatoshi , Kouno Isao
Published: July 2006

Troponoids were shown to form 2:1-complexes with β-cyclodextrin and 1:1-complexes with α-cyclodextrin. The photoisomerization of complexed tropolone and 2-methoxytropone gave optically active 1-hydroxy- and 1-methoxybicyclo[3.2.0]hepta-3,6-dien-2-ones in improved yields. The pyrolysis of the (+)-1-methoxybicyclo[3.2.0]hepta-3,6-dien-2-one gave the (+)-3-methoxybicyclo[3.2.0]hepta-3,6-dien-2-one, ruling out the two-fold supra-antara-1,3-sigmatropy.
The Synthesis of Benzofuroquinolines. II. Two Benzofuroquinolinones and Some Benzofuroquinoline Derivatives
Authors: Kawase Yoshiyuki , Yamaguchi Seiji , Morita Mariko , Uesugi Taeko
Published: July 2006

Two benzofuroquinolinones, 6,11-dihydrobenzofuro[2,3-b]quinolin-11-one and 5,6-dihydrobenzofuro[3,2-c]quinolin-6-one, were obtained by the demethyl-cyclization of 4-hydroxy-3-(o-methoxyphenyl)-1,2-dihydroquinolin-2-one. The chlorination of these benzofuroquinolinones afforded the corresponding chlorobenzofuroquinolines which were then converted to the cyanobenzofuroquinolines. The linear chlorobenzofuroquinoline was converted to 11-methoxy- and 11-ethoxybenzofuro[2,3-c]quinolines, and the linear cyanobenzofuroquinoline to benzofuro[2,3-b]quinoline-11-carboxylic acid and -11-carboxamide. The linear benzofuroquinolines thus obtained were oxidized to the corresponding N-oxides.
Thermodynamic Relation of Interfacial Tensions in Three Fluid Phases
Authors: Tajima Kazuo , Tsutsui Takao , Murata Hiroshi
Published: July 2006

The thermodynamic relation was derived for the interfacial tensions at the three interfaces of two immiscible solutions and their vapor phase at a constant temperature. The relation obtained was experimentally tested by measuring each interfacial tension of systems which consisted of organic (alcohols(C4–C10), triolein, and hexadecane) and aqueous phases. The relation of the interfacial tensions was valid for the polar oil–water systems, but not for the hexadecane–water system unless a surfactant was added.
The Partial Molar Quantity of the Sulfur of the Compounds in the Fe–V–S System
Authors: Wada Hiroaki
Published: July 2006

An equilibrium study of the Fe–V–S system was carried out under controlled sulfur-pressure conditions. Partial molar enthalpies of the sulfur of the compounds in the Fe–V–S system were calculated on the basis of the Ps2–T–X relations, which were established at temperatures between 520 and 814 °C.
Electronic Structures of Purine Bases Studied by Electrochemical-ESR Techniques. Spin Distribution in Purine Anion Radical
Authors: Ohya-Nishiguchi Hiroaki , Shimizu Yasunori , Hirota Noboru , Watanabe Kohji
Published: July 2006

We have investigated the ESR spectrum of anion radical of purine generated electrochemically using a helical electrode cell for low-temperature ESR measurements. The assignment of the hfcc was made with the aid of partial deuteration and MO calculations. The most notable observation is that about 45% of the spin density is localized at position 6. This correlates well with the preferential hydrogenation at this position. The McLachlan method reproduces the observed spin distribution well with βN9C⁄βCC=1.0 which indicates that the bonding between the nitrogen at 9 and carbons at 4 and 8 have large double bond characters. The INDO-MO calculations based on the two molecular geometries for 9H-purine also agree well with the experimental data. Finally the effect of tautomerism of purine on the spectrum is discussed.
Organonickel(II) Complexes Containing Carbon-bonded Heterocycles as a Ligand
Authors: Isobe Kiyoshi , Nakamura Yukio , Kawaguchi Shinichi
Published: July 2006

Oxidative addition reactions of 2- and 3-chloropyridines and of 2-chloropyrazine to tetrakis(triphenylphosphine)nickel(0) occurred in toluene at ambient temperature to afford dinuclear nickel(II) complexes containing carbon-bonded heterocycles as a ligand. They are quite stable and the bridging chloride was readily substituted by other halides and pseudohalides preserving the dinuclear structure. 8-Chloroquinoline yielded a mononuclear complex as an exception. These novel organonickel(II) complexes were characterized by analytical and molecular weight data together with IR, 1H NMR, and 13C NMR spectra. Di-μ-chloro-bis(2-pyridyl)bis(triphenylphosphine)dinickel(II) was found to be an excellent catalyst for selective cross coupling of 2-chloropyridine with methylmagnesium bromide.
Vibrational Distribution of HF Produced by Mercury Photosensitized Decomposition of Fluoroethylenes
Authors: Watanabe Hajime , Horiguchi Hiroyuki , Tsuchiya Soji
Published: July 2006

Distributions of vibrationally excited HF produced by Hg-photosensitized reactions of fluoroethylenes are determined by means of the IR emission measurement of HF fundamentals. The distributions are almost of Boltzmann type with temperatures of 11400, 13700, 7200, 5700, 5700, and 2200 K for respective parent molecules of CH2=CHF, CH3CF=CH2, CH2=CF2, cis-, trans-CHF=CHF, and CHF=CF2. The fractions of vibrational energy of HF† among the energies available for distribution in various degrees-of-freedom of product molecules are 19, 23, 11, 7.6, 7.6, and 1.7% for the above molecules, respectively. The statistical calculation results in much less energy disposal in HF vibration in the decompositions of CH2=CHF, CH3CF=CH2, and CH2=CF2, while the distributions of HFt in CHF=GHF and CHF=CF2 are closer to those predicted by the statistical calculation. The deactivation rate of HF† in CH2=CHF is about three times larger than that in CH2=CF2, and the latter values resemble those in HF.
In Situ Measurement of Electrode Surface Change by Photoacoustic Spectroscopy
Authors: Masuda Hideki , Fujishima Akira , Honda Kenichi
Published: July 2006

Photoacoustic spectroscopy (PAS) was used for the study of electrode-electrolyte interfaces in situ. The design of the PAS cell and the experimental procedure are given. The change in absorption at the interface during electrochemical reaction at Au electrodes, as measured by PAS technique, is described.
Polymer Effects under Pressure. IV. The Hydrolysis of Phenyl Esters Catalyzed by α-Chymotrypsin up to 2000 bar
Authors: Taniguchi Yoshihiro , Suzuki Keizo
Published: July 2006

The rates of the hydrolysis of 2-valeryloxy(C5)- and 2-heptanoyloxy(C7)-benzoic acids catalyzed by α-chymotrypsin (α-CHT) were measured at pressures up to 2000 bar at 30 °C and pH 7.8 in a 0.05 M Tris buffer solution. The apparent Michaelis constant, Kmapp, was estimated to vary from 5.9 to 9.9 mM, and kcat from 11×10−3 to 52×10−3 s−1, for the C5 ester, and Kmapp, from 4.7 to 10 mM, and kcat from 37×10−3 to 200×10−3 s−1, for the C7 ester, between 1 and 2000 bar. From the pressure dependences of Kmapp and kcat, the volume changes accompanying the dissociation of the enzyme–substrate complex and the activation volume for the process of the product formation were calculated to be −6.3±2 and −20±2 cm3/mol for the C5 ester and −9.5±2 and −21±2 cm3/mol for the C7 ester. The effects of the pressure on the hydrolysis of p-nitrophenyl acetate (PNPA) catalyzed by α-CHT have also been measured up to 3000 bar at pH 7.8 in a 0.05 M Tris buffer solution and at 25 °C and 35 °C. The activation volumes were −3 cm3/mol at 25 °C and −4 cm3/mol at 30 °C and 25 °C. These results were discussed on the basis of the X-ray study of the enzyme-substrate complex.