bluuebunny/crossref_metadata_2025 huggingface dataset:
Coenzyme Models. XII. Kinetics and Mechanisms of 1,4-Dihydro-nicotinamide Reduction of Carbon-Carbon Double Bonds. Influence of Added Mg2+ Ion and Acetic Acid
Authors: Shinkai Seiji , Kusano Yumiko , Ide Toyoko , Sone Takaaki , Manabe Osamu
Published: July 2006

Nonenzymatic dihydronicotinamide reduction of carbon-carbon double bonds occurs with the aid of Mg2+ ion or acetic acid. The role of Mg2+ ion and acetic acid is discussed on the basis of spectral studies, kinetic measurements, and product analyses. The addition of Mg2+ ion caused the shift of the NMR peak of substrate α-proton to lower field, and the magnitude was parallel to the yield of reduced methylene derivatives. Kinetic studies suggested that the dihydronicotinamide reduction in the presence of Mg2+ ion is most reasonably understood by assuming a competitive complexation of dihydronicotinamide and substrate with Mg2+ ion. On the other hand, acetic acid aids the reduction by means of general acid catalysis, but an alternative mechanism is suggested for the reduction of benzylidenemalononitrile.
Oxidation of 2,5-Dimethoxyacetophenone Derivatives with Thallium(III) Nitrate in Trimethyl Orthoformate–Methanol. I
Authors: Maruyama Kazuhiro , Kozuka Tadashi
Published: July 2006

Alkyl-substituted 2,5-dimethoxyacetophenones were oxidized with thallium(III) nitrate in methanol–trimethyl orthoformate (TMOF) to give methyl alkyl-substituted 2,5-dimethoxyphenylacetates in a good yield. A simple modification of separating method from the reacting mixture allowed us to obtain the corresponding methyl (alkylsubstituted 3,6-dioxo-1,4-cyclohexadienyl)acetates.
Isomerization of cis-2-Butene Caused by Electronically-excited Sulfur Dioxide (3B1) Adsorbed on Porous Vycor Glass
Authors: Otsuka Kiyoshi , Fukaya Masaki , Morikawa Akira
Published: July 2006

The cis-trans isomerization of cis-2-butene caused by electronically-excited sulfur dioxide has been studied at the gas-solid interface of porous Vycor glass. All of the quantum yields for the isomerization obtained gave values larger than ≈30. Infrared studies show that the product on the glass is the polysulfone formed through the copolymerization of sulfur dioxide and cis-2-butene. These results and the kinetic data for the isomerization can be explained satisfactorily by the proposed mechanism in which the isomerization occurs through the addition and elimination of 2-butene molecules at the terminal of the polysulfone formed on the glass; the copolymerization is initiated by an electronically-excited SO2 (3B1) state.
Determination of Absolute Configuration of Epishamixanthone, a Metabolite of Aspergillus rugulosus, by Anomalous Scattering of Light Atoms
Authors: Fukuyama Keiichi , Hamada Kensaku , Tsukihara Tomitake , Katsube Yukiteru
Published: July 2006

The absolute configuration of epishamixanthone has been determined from the Bijvoet differences by anomalous scattering of light atoms for Cu Kα radiation. To verify the determination, the absolute configuration of sterigmatocystin which was already determined has been examined by the same procedure. The reliability of the Bijvoet differences calculated from the structure has been estimated by means of the probability method. The errors in the measured values of the Bijvoet differences have been analysed by the normal probability plot. The accuracy of the measurement may be affected considerably by the habit of crystal. The present analysis has established that the configurations of two asymmetric carbon atoms in epishamixanthone are both R.
Studies of the Adsorbing Particle Flotation of Fe3+ and Cu2+
Authors: Kobayashi Koichi , Natori Kenichi , Kamaya Masamizu , Sasaki Tsunetaka
Published: July 2006

The adsorbing particle flotation of Fe2+ or Fe3+ and Cu2+ ions was studied by the combined use of bentonite (Bt) and a cationic surfactant, benzylhexadecyldimethylammonium chloride (BHDAC). Fe3+ ions were effectively floated from an aqueous solution by the use of Bt and cationic surfactant in a manner similar to the flotation by the use of sodium silicate and cationic surfactant. Most Fe2+ ions were found to be floated as Fe3+ ions, when the pH was increased by the addition of sodium hydroxide. The maximum floatability of 98% was obtained for Fe3+ under optimum conditions. The pH corresponding to the beginning of flotation of Fe3+ was influenced by the manner in which the pH of the solution was controlled. Cu2+ ions could also be floated, but less effectively than Fe3+ ions. Selective flotation of Fe3+ from the mixed solution of Fe3+ and Cu2+ was attempted and effectively achieved.
A Kinetic Study of the Ligand Exchange between Bis(acetylacetonato)-oxovanadium(IV) and Acetylacetone[14C] in Organic Solvents
Authors: Nishizawa Masato , Saito Kazuo
Published: July 2006

Square pyramidal [VO(acac)2] (acac, acetylacetonate) undergoes ligand exchange with Hacac[14C] in 1,2-dichloroethane (DCE) without side reactions. The rate is expressed by R=k2[complex] [Hacac], where [Hacac] stands for the concentration of free acetylacetone in enol form. The second order rate constant and activation parameters are 0.071 M−1 s−1 (M=mol dm−3) at −33 °C, ΔH\eweq=(46.7±1.7) kJ mol−1 and ΔS\eweq=(−61.9±8.4) J· mol−1 K−1. The deuterium isotope effect is kH⁄kD=1.3±0.2. It appears as if the free Hacac first interacts with the complex as unidentate and the chelation of the unidentate accompanied by proton transfer to the leaving acac− is the rate determining step. On addition of a donor solvent the exchange rate decreases, and the extent is correlated with Gutmann’s donor number. The k2, ΔH\eweq and ΔS\eweq in 0.06 M dimethyl sulfoxide (DMSO) in DCE are 0.0038 M−1 s−1 at −33 °C, (71.9±10.0) kJ mol−1, and (−4±40) J mol−1 K−1, respectively. The DMSO molecule seems to interact with the intermediate species with a unidentate Hacac and inhibits the associative rate determining step.
Synthesis of Carbamic Ester by a Reaction of Carbon Dioxide, Tetrakis(dimethylamido)titanium(IV) and Epoxide
Authors: Yoshida Yasuhiko , Inoue Shohei
Published: July 2006

2-Hydroxycyclohexyl dimethylcarbamate was synthesized quantitatively by a reaction of carbon dioxide, tetrakis (dimethylamido) titanium(IV) and 1,2-epoxycyclohexane.
Cyclic Peptides. IV. Synthesis of Diastereomeric Dihydro-AM-toxin I and Its Analogs
Authors: Shimohigashi Yasuyuki , Lee Sannamu , Kato Tetsuo , Izumiya Nobuo
Published: July 2006

Diastereomeric cyclotetradepsipeptides [l-Ala2]– and [d-Ala2]–AM-toxin I, corresponding to the hydrogenated products of AM-toxin I, were synthesized by the conventional method and their biological activities were tested. [d-Ala2]–AM-toxin I exhibits weak but recognizable necrotic activity (5–10 μg/ml) on apple leaves. [l-Ala2]–AM-toxin I is inactive even in a high concentration of 100 μ/ml. The results of NMR and ORD measurements of [d-Ala2]–AM-toxin I and [l-Tyr(Me)1, d-Ala2]–AM-toxin indicates the presence of a common conformer. The results on [l-Ala2]–AM-toxin I and [l-Tyr(Me)1, l-Ala2]–AM-toxin revealed the presence of more than two conformers, the predominant conformation differing from that of d-isomers. Difference in activity between [d-Ala2]– and [l-Ala2]–AM-toxin I can be attributed to the difference in conformation of the diastereomers.
The Substituent Effect. XII. Solvolysis of 3′- and 4′-Substituted 1-(4-Biphenylyl)ethyl Chlorides
Authors: Tsuno Yuho , Chong Wei-Yuen , Tairaka Yoshihiko , Sawada Masami , Yukawa Yasuhide
Published: July 2006

Rate constants of solvolysis of 3′- and 4′-substituted 1-(4-biphenylyl) ethyl chlorides were measured in 80% (v/v) aqueous acetone. The effect of substituents could be correlated excellently with the LArSR relationship.

log k⁄k0=−1.56(σ0+0.84Δ\barσR+)

The ρ and r+ values are smaller than those in the corresponding phenyl system under identical conditions (ρ=−4.95, r+=1.15). The difference of the r+ values is interpreted in terms of twisting of the two phenyls around the pivot bond in biphenyl. The same treatment has been applied successfully to other sets of reactivity data; solvolysis, protodesilylation, alkaline hydrolysis, and piperidinodebromination. The results indicate a consistently reduced effectiveness of pi-electronic transmission in biphenylyl relative to phenyl system in all reactions studied.
The Extraction of Alkali Metal Picrates into Benzene by Means of 18-Crown-6
Authors: Iwachido Tadashi , Sadakane Akira , Tôei Kyoji
Published: July 2006

The distribution of alkali metal picrates between water and benzene was investigated in the presence of 18-crown-6. The overall equilibrium constants, Kex, and some constituent equilibrium constants were determined. The Kex value increases, passes through a maximum (at potassium), and falls off as the size of the alkali metal cation increases.
Electronic Spectra and Charge-Transfer Absorption of Solid Anion Radical Salts of 2,3-Dicyano-p-benzoquinone and 2,3-Dichloro-5,6-dicyano-p-benzoquinone
Authors: Iida Yôichi
Published: July 2006

The diffuse reflection spectra were measured with solid anion radical salts of 2,3-dicyano-p-benzoquinone and 2,3-dichloro-5,6-dicyano-p-benzoquinone with rubidium and caesium cations. Strong charge-transfer transition between anion radicals was observed in the lowenergy region. The spectroscopic features of the chargetransfer absorption were discussed in terms of one-dimensional Hubbard model.
Heat of Adsorption of Ammonia on Silica-Alumina at Low Surface Coverage
Authors: Masuda Tatsuo , Taniguchi Hitofumi , Tsutsumi Kazuo , Takahashi Hiroshi
Published: July 2006

Heats of adsorption of ammonia on silica-alumina at very low surface coverage were measured in details. The effects of ammonia adsorption on the glass wall and on the greese were corrected. The initial heat value agreed fairly well with the heat of neutralization of NH3(G) and HCl(G). The diffusion of the gas had little effect on the value of heat of adsorption.
Nuclear Magnetic Resonance Studies of Cobalt Complexes. Cobalt-59 Nuclear Magnetic Resonance Spectrum of the Hexakis-(trimethyl phosphite)cobalt(III) Complex
Authors: Yamasaki Akira , Aoyama Takashi , Fujiwara Shizuo , Nakamura Keikichi
Published: July 2006

The well-resolved septet spectrum was recorded for cobalt-59 NMR of [Co(P(OCH3)3)6](BF4)3 in an acetonitrile solution. The obtained NMR parameters are: σ(Co-59)=+304 ppm (upfield from [Co(CN)6]3−), 1J(Co–P)=414 Hz, and ΔH(Co)=340 Hz.
The Reaction of ortho-Palladated Ferrocene Complexes with Olefins
Authors: Izumi Taeko , Endo Kazuyoshi , Saito Osamu , Shimizu Iwao , Maemura Mitsugi , Kasahara Akira
Published: July 2006

ortho-Palladation products of (dimethylaminomethyl)ferrocene and 2-pyridylferrocene were treated with various olefins under mild conditions. A variety of unusual 1,2-disubstituted ferrocene derivatives were obtained from these reactions.
Fluorescence and Dual Phosphorescence Spectra of Quinoxaline in Fluid Solution
Authors: Yamamoto Kohzaburo , Takemura Takeshi , Baba Hiroaki
Published: July 2006

Fluorescence and phosphorescence spectra of quinoxaline in isooctane (2,2,4-trimethylpentane) have been measured under fluid conditions. The fluorescent emission with a spectral maximum at 410 nm is assigned to the 1(n,π*)→S0 fluorescence of quinoxaline. A new phosphorescence spectrum appears in a wavelength region longer than 520 nm as the concentration of quinoxaline increases, in addition to the phosphorescence spectrum of the monomer. From the results of photostationary and transient experiments on the concentration and/or temperature dependence of phosphorescence, it has been confirmed that the phosphorescence consists of two components attributable to the monomer and the excimer.
Vibration Spectra and Rotational Isomerism of Chain Molecules. VII. 1-Chloro-, 1-Bromo-, and 1-Iodopropanes, and 1-Chloro-, 1-Bromo-, and 1-Iodobutanes
Authors: Ogawa Yoshiki , Imazeki Shuji , Yamaguchi Hiroko , Matsuura Hiroatsu , Harada Issei , Shimanouchi Takehiko
Published: July 2006

The Raman and infrared spectra of 1-chloro-, 1-bromo-, and 1-iodopropanes, CH3CH2CH2X (X=Cl, Br, and I), and 1-chloro-, 1-bromo-, and 1-iodobutanes, CH3CH2CH2CH2X (X=Cl, Br, and I), were measured for the gaseous, liquid, glassy, and crystalline states. The normal vibration frequencies were calculated, a consistent set of force constants explaining the frequencies of basic halogenoalkanes being assumed. The rotational isomerism was studied on the basis of the spectral observations and the normal coordinate calculations. The enthalpy differences among the rotational isomers were examined.
The Crystal Structure of the Ammonium Bromide Complex of 1,4,7,10,13,16-Hexaoxacyclooctadecane (18-Crown-6), C12H24O6·NH4Br·2H2O
Authors: Nagano Osamu , Kobayashi Akiko , Sasaki Yukiyoshi
Published: July 2006

Ammonium bromide forms a 1 : 1 complex with cyclic polyether “18-crown-6.” The crystals of C12H24O6·NH4Br·2H2O are orthorhombic, with the space group of Pnam and with cell constants of a=10.002(3), b=12.716(4), c=15.073(4) Å, and Z=4. The structure was solved by the conventional heavy-atom technique and refined by the full matrix least-squares method to R=0.099 for 1033 independent reflections. The 18-crown-6 has a conformation with a pseudo D3d symmetry. The ammonium cation is displaced by 1.00 Å from the mean oxygen plane of the 18-crown-6 and interacts with the nearest bromide anion. The relationship between the cation and the 18-crown-6 resembles those of the C12H24O6·RbNCS and C12H24O6·CsNCS complexes. On the difference Fourier maps, four electron-density peaks were detected at reasonable positions for the hydrogen atoms of the amonium cation.
Polarographic Behavior of Tris(acetylactonato)ruthenium(III) in Aqueous and Acetonitrile Solutions
Authors: Endo Akira , Watanabe Masayuki , Hayashi Sadayuki , Shimizu Kunio , Satô Gen P
Published: July 2006

In tetraethylammonium perchlorate-acetonitrile solution, [Ru(acac)3] was reversibly reduced at the dropping mercury electrode to [Ru(acac)3]− with a conditional electrode reaction rate-contsant estimated to be ca. 0.2 cm s−1 or larger. The reduced form was stable in the solution under an inert gas atmosphere. In aqueous solutions, [Ru(acac)3] was reduced reversibly when the depolarizer concentration was less than 0.07 mol m−3 at 25 °C. At higher depolarizer concentrations, [Ru(acac)3] molecules were adsorbed onto the mercury surface, and the free molecules in solution were reduced through the adsorbed layer at a smaller rate; the adsorbed layer was removed at a certain negative potential, and the reversible reduction took place normally at the bare surface. The difference between reversible half-wave potentials observed in acetonitrile and aqueous solutions was discussed in terms of solvation energies of the oxidized and reduced forms.
The Reductive Deacylation of the Knoevenagel Condensates by the Use of the Tetracarbonylhydridoferrate(0) Anion. A New Synthetic Route of Ketones from Aldehydes
Authors: Yamashita Masakazu , Watanabe Yoshihisa , Mitsudo Take-aki , Takegami Yoshinobu
Published: July 2006

The Knoevenagel condensates prepared from 2,4-pentanedione with aldehydes were allowed to react with the tetracarbonylhydridoferrate(0) anion in ethanol to give reductively deacylated monoketones in high yields. However, the exclusive reduction of the α,β-unsaturated double bond of the same condensates was encountered when the reaction was carried out in such a solvent as tetrahydrofuran and acetone. The Knoevenagel condensates, derived from the reaction of ethyl acetoacetate and/or ethyl benzoylacetate with aldehydes, were simply reduced even in ethanol. The reaction mechanism is briefly discussed.
Synthesis of Hindered t-Alkyl Ethers
Authors: Masada Hiromitsu , Sakajiri Tadahide
Published: July 2006

Di-t-butyl ether was prepared in 6–73% yields by the reactions of t-butyl halide with Ag2CO3, Ag2O, HgO, ZnO, ZnCO3, PbO2, Cu2(CO3)(OH)2, and Tl2O3 at 20–65 °C in hydrocarbons under nitrogen. Similar reactions gave seven new hindered di-t-alkyl ethers: di-t-pentyl ether, bis(1,1-dimethylbutyl) ether, bis(1-ethyl-1-methylpropyl) ether, bis(1,1-dimethylpentyl) ether, bis(1-ethyl-1-methylbutyl) ether, bis(1,1-diethylpropyl) ether, and bis(1,1-dimethylhexyl) ether. The yield of di-t-alkyl ether decreased as the t-alkyl group became bulky. A slight difference in the skeletal structure of the t-alkyl halide markedly influences the substitution. The reaction pathways are elucidated on the basis of the experimental results.
Synthetic Studies of Pyridomycin. II. Synthesis of a Model Twelve-membered Ring Compound Related to Pyridomycin
Authors: Kinoshita Mitsuhiro , Awamura Masaki
Published: July 2006

A prototypic compound of pyridomycin, 6-(3-hydroxypicolinoylamino)-5-methyl-8-aza-1,4-dioxacyclododecane-3,7,12-trione (11), was synthesized. 4-(Benzyloxycarbonylamino)butyric acid was coupled with t-butyl glycolate in the presence of DCCI and pyridine to afford t-butyl [4-(benzyloxycarbonylamino) butyryloxy] acetate (4). De-t-butylation of 4 followed by condensation with N-t-butoxycarbonyl-l-threonine benzyl ester by the DCCI method gave O-[{4-(benzyloxycarbonylamino)butyryloxy}acetyl]-N-t-butoxy-carbonyl-l-threonine benzyl ester (6). Deprotection of 6 followed by cyclization with Woodward’s reagent K afforded 6-(t-butoxycarbonylamino)-5-methyl-8-aza-1,4-dioxacyclododecane-3,7,12-trione (21% yield), which was transformed into the title compound 11.
The Chlorination of Hydrocarbons. XIV. The Chlorination of Vinyl Compounds
Authors: Shinoda Kiyonori
Published: July 2006

The competitive chlorination of various vinyl compounds was carried out in order to elucidate the effect of the structure on the addition rate of chlorine to a double bond. A linear free-energy relationship was found to exist between the reactivities in the presence of oxygen and Taft’s σ* constants. The ρ* value was calculated to be −1.20. On the other hand, the plot deviated slightly from a straight line; this shows the Taft relationship between the reactivities for the photochlorination and σ* values, known as an extra acceleration due to the hyperconjugation of the alkyl group.
14N Nuclear Quadrupole Resonance of Some Heterocyclic Compounds via Nuclear Double Resonance
Authors: Maruizumi Takuya , Hiyama Yukio , Watanabe Noriyuki , Niki Eiji
Published: July 2006

Using proton-nitrogen double resonance in the laboratory frame, the 14N nuclear quadrupole resonances (NQR) of 2,4(1H,3H)-pyrimidmedione[uracil], 2,3-dihydro-2-thioxo-4(1H)-pyrimidinone[2-thiouracil], 2,4(1H,3H)-pyrimidinedithione[2,4-dithiouracil], and 1,3-dihydro-2H-benzimidazole-2-thione[2-mercaptobenzimidazole] have been measured at room temperature. The NQR parameters of uracil and its sulfur-substituted compounds are interpreted by using the Townes and Dailey theory.
Inositol Derivatives. 11. Synthesis of Dianhydroinositols
Authors: Ogawa Seiichiro , Oki Shuichi , Suami Tetsuo
Published: July 2006

All the predicted isomers of 1,2 : 3,4- and 1,2 : 4,5-dianhydrocyclohexanehexols (5 racemates and 6 mesocompounds) were synthesized from appropriate inositol ditosylates and dimesylate by treatment with sodium methoxide.
The Reaction of Vicinal Dinitro Compounds with Tin(II) Chloride
Authors: Fukunaga Kimitoshi , Kimura Makoto
Published: July 2006

The reactions of vicinal dinitro compounds with tin(II) chloride have been studied. The reactions of α,β-diaryl vicinal dinitro compounds and tin(II) chloride in polar solvents gave the corresponding olefins in good yields. The aliphatic vicinal dinitro compounds did not react with tin(II) chloride under the same reaction conditions. A reaction mechanism of elimination involving a radical anion intermediate has been proposed.
The X-Ray Structure Determination of Heptaethylene Glycol–Sr(SCN)2
Authors: Ohmoto Hideyo , Kai Yasushi , Yasuoka Noritake , Kasai Nobutami , Yanagida Shozo , Okahara Mitsuo
Published: July 2006

The crystal structure of heptaethylene glycol–Sr(SCN)2 has been determined by X-ray diffraction. The Sr ion is coordinated by eight oxygen atoms arising from the heptaethylene glycol moiety and a nitrogen atom from one of SCN groups. The coordination polyhedron is irregular, Sr–O distances ranging from 2.56 to 2.73 Å.
The Extraction Spectrophotometric Determination of Cobalt(II) with 4-(2-Thiazolylazo)resorcinol and Zephiramin
Authors: Ueda Kazumasa
Published: July 2006

The cobalt(II)–4-(2-thiazolylazo)resorcinol chelate anion is quantitatively extracted into chloroform with a cation of zephiramin as an ion-pair complex. This process was applied to the spectrophotometric determination of cobalt. The effective separation and the sensitive determination for a trace amount of cobalt could be confirmed even in the presence of high concentrations of masking agents.
The Reaction of 3,5-Diphenyl-1,2-dithiolium Perchlorate with Active Methylenes
Authors: Shibuya Isao
Published: July 2006

3,5-Diphenyl-1,2-dithiolium perchlorate (1) was synthesized in a new, convenient way, and the reaction of 1 with several active methylene compounds was studied. The compounds possessing no less than one ester group gave novel products, 3-substituted 4,6-diphenyl-2H-thiopyran-2-ones, while those possessing a carbamoyl group gave 3-substituted 2-hydroxy-4,6-diphenylpyridines or 3-cyano-1,4,6-triphenyl-2-pyridone. Malononitrile, however, gave 1-mercapto-1,3-diphenyl-4,4-dicyanobutadiene (10). On treatment with methyl iodide or p-chlorobenzyl chloride, 10 gave 1-methylthio- or 1-(p-chlorobenzylthio)-1,3-diphenyl-4,4-dicy-anobutadiene, and also led to bis(1,3-diphenyl-4,4-dicyanobutadienyl) disulfide on treatment with hydrogen peroxide.
Cobalt Metallocycles. VII. η5-Cyclopentadienyl-η4-iminocyclopentadienecobalt Complexes from a Reaction of Cobaltacyclopentadienes with Isocyanides
Authors: Yamazaki Hiroshi , Wakatsuki Yasuo
Published: July 2006

The reaction of (η5-cyclopentadienyl)(triphenylphosphine) cobaltacyclopentadienes with isocyanides gives η5-cyclopentadienyl-η4-iminocyclopentadienecobalt complexes in good yields. Treatment of the product with HBF4 or CH3I yields the corresponding aminocobalticinium salt.
An ESR Study on the Working States of a Pure V2O5 Crystal under the CO-oxidation
Authors: Kera Yoshiya , Kuwata Keiji
Published: July 2006

The V2O5 crystal, prepared from the pure V2O5 powder by a zone-melting method in the air, did not show any ESR signal. When the crystal came into contact with a mixture of CO and O2 ((CO/O2)≥4), an ESR spectrum with the hfs of 15-lines (g⁄⁄=1.932, g⊥=1.978; 〈g〉=1.963), which has been previously ascribed to an oxygen defect, was found at the beginning, but after prolonged contact a sharp spectrum (〈g〉=1.954) appeared. The intensity of the hf-lines was constant but that of the sharp spectrum increased with the contact time. The g-value and line shape of both spectra did not change with the contact time. The same spectra were also found in the crystal grown under a mixture of CO and O2. On the thermal decomposition of pure NH4VO3in vacuo a similar spectrum with a sharp line was found. The g-value became lower in the sample reduced further by SO2 after the thermal decomposition. With reference to the data of TGA, DTA, magnetic susceptibility (χmol), and X-ray analysis of the vanadium oxides, the sharp spectrum was ascribed to a lower oxide or oxide state such as V3O7. Based on the ESR results, the working state of pure V2O5 crystal under CO-oxidation and its catalytic property are discussed.
An Estimation of the Thermodynamic Properties of Organic Compounds in the Ideal Gas State. I. Acyclic Compounds and Cyclic Compounds with a Ring of Cyclopentane, Cyclohexane, Benzene, or Naphthalene
Authors: Yoneda Yukio
Published: July 2006

A new group-contribution method for estimating the standard enthalpy of formation, the standard absolute entropy, and the standard molar heat of organic compounds in the ideal gas state is proposed with tables of the contribution values. This method (the ABWY method) is a completely revised and enlarged version of the Anderson, Bayer, and Watson method, and it can be used with regard to a more diverse variety of compounds with a higher reliability. The neighboring effects in group-contribution methods are introduced to obtain better estimated values. The substitutions of various functional groups on aromatic rings are discriminated. Type-number corrections of the functional groups and multiple-substitution effects of halogens are also introduced; thus even heterofunctional compounds can be processed. A new concept, the quality of contribution values, is proposed to designate the qualitative reliability of the estimated physical properties. The manual procedures and tables of contribution values are given for estimating the thermodynamic properties of the compounds, as mentioned in the title, composed of C, H, O, halogens, S, and N. This method was critically compared with the Benson method in versatility and reliability.
Synthetic Studies of Laurencin and Related Compounds. V. Transformation of cis-2-Ethyl-8-formyl-3,4,7,8-dihydro-2H-oxocin-3-one 3-Ethylene Acetal into (±)-Laurencin
Authors: Masamune Tadashi , Murase Hisashi , Matsue Hajime , Murai Akio
Published: July 2006

Transformation of the title starting material into (±)-laurencin, which implies synthesis of the natural product, is described. The structure and configuration of synthetic intermediates are defined on the basis of the spectral evidence.
The σ-Bonded Palladium(II) Complex of (Dimethylaminomethyl)ruthenocene
Authors: Kamiyama Shin-ichi , Kimura Tetsuo , Kasahara Akira , Izumi Taeko , Maemura Mitsugi
Published: July 2006

The reaction between (dimethylaminomethyl)ruthenocene with lithium tetrachloropalladate(II) in the presence of sodium acetate gave di-μ-chloro-bis[2-(dimethylaminomethyl)ruthenocenyl]dipalladium(II) (2). The σ-bonded structure of 2 has been confirmed by IR analysis and the reactions of 2 with triphenylphosphine, thallium(I) acetylacetonate, and lithium aluminum deuteride. The reactions of chloro [2-(dimethylaminomethyl)ruthenocenyl](triphenylphosphine)palladium(II) with carbon monoxide and 2 with methyl vinyl ketone, phenyl vinyl ketone, and styrene have been examined. 1,2-Disubstituted ruthenocene derivatives have been obtained in higher yields than those of the corresponding ferrocene derivatives.
Improvement of Acetone Yield in the Oxidation of Propylene
Authors: Ai Mamoru , Ozaki Atsumu
Published: July 2006

The outstanding property of the SnO2–MoO3 catalyst in the oxidation of propylene to acetone was confirmed by tests of various oxide catalysts supported on pumice. The optimum composition was found to be SnO2-70/MoO3-30 mol % for the oxidation at from 170 to 260 °C. It was also found that this pumice-supported catalyst is sufficiently selective for the acetone formation even at a high temperature of 260 °C, and that it gives a high yield of acetone while keeping its high selectivity. The selectivity increases up to 90 mol % with an increase in the partial pressure of water vapor and with a decrease in the oxygen partial pressure. On the basis of such information, it can be said that a high yield of acetone can be obtained by the divided introduction of oxygen.
New Ring Opening Reactions of Oxiranes with Aryl Carboxylates
Authors: Funahashi Kazutoshi
Published: July 2006

Oxiranes reacted with aryl esters in the presence of base. The reactions of aryl carboxylates with alkyloxiranes afforded almost exclusively 1-alkyl-2-(aryloxy) ethyl carboxylates, whereas the reactions with aryloxiranes gave a mixture of 1-aryl-2-(aryloxy) ethyl carboxylates and 2-aryl-2-(aryloxy) ethyl carboxylates. Similar results were also obtained in the reaction with S-aryl thiocarboxylates and diaryl carbonates. The rate of reaction between phenyl acetate and phenoxymethyloxirane (PMO) in the presence of tributylamine (n-Bu3N) as a catalyst has been determined in the temperature range 110 to 130 °C and may be expressed by –d[PMO]⁄dt=k2[n-Bu3N]·[PMO]. The apparent activation energy calculated from the Arrhenius plots is 85.8 kj/mol. The reaction catalyzed by tributylamine is assumed to proceed through zwitter ions, n-Bu3\overset+NCH2CH(R)O− and n-Bu3\overset+NCH(R)CH2O−, which attack aryl carboxylate.
Determination of Self-diffusion Coefficient of Nickel in Nickel Sulfide
Authors: Kotani Kazuo , Ota Kenichiro , Aizawa Takemi , Fueki Kazuo
Published: July 2006

The self-diffusion coefficient of nickel in nonstoichiometric nickel sulfide, Ni1−δS, was measured as a function of δ, using 63Ni in the temperature range of 550–750 °C. At δ=0.028, the self-diffusion coefficient, DNi*, was expressed by the following equation:

D Ni *=3.3×10−7exp\left(−\frac73.2±9.2⁄kJ mol−1RT\ight)m2 s−1

At 550 °C and 650 °C, DNi* increased with an increase in δ from 0 to 0.04 and tended to reach the saturation point above δ=0.04.
Disproportionation of Propylene over MoO3–SiO2 Catalyst with Various Treatments
Authors: Sodesawa Toshiaki , Ogata Eisuke , Kamiya Yoshio
Published: July 2006

Disproportionation of propylene over MoO3–SiO2 (atomic ratio: Mo/Si=1/25) catalyst treated with HCl and aqueous ammonia was studied in the temperature range 350–600 °C under atmospheric pressure. The activity of MoO3–SiO2 catalyst extracted with aqueous ammonia remained for a long time, since most of free MoO3 was removed from the MoO3–SiO2 surface. This gave rise to increase in the selectivity for disproportionation of propylene to ethylene and butenes and decrease in the selectivity for hydrogenation, isomerization and polymerization. When MoO3–SiO2 not subjected to treatment was pretreated by H2 gas, it showed higher catalytic activity and lower selectivity for disproportionation than the one treated by N2 gas.
Synthesis and Reactions of Perylenecarboxylic Acid Derivatives, VI. Sulfonation of 3,4-Perylenedicarboximide
Authors: Nagao Yukinori , Misono Takahisa
Published: July 2006

The sulfonation of 3,4-perylenedicarboximide (1) with sulfuric acid has been studied. The position of the sulfo group in the monosulfonated product (2) obtained at 100 °C has been discussed on the basis of the NMR and IR spectra of 2 and the related compounds, and has been confirmed to be the 9-sulfoperylene-3,4-dicarboximide. The localized treatment of 1 by H\ddotuckel and Pople MO calculations confirmed substitution at the 9-position. Paper chromatographic analysis indicated that the reaction product was only 2 in the temperature range 60–120 °C, and the reaction rate was determined spectroscopically. The maximum formation of 2 was approximatedly 97% at 100 °C. The rate of reaction was found to be a pseudo first order process and the activation energy found to be 19.5 kcal/mol.
A Highly Stereospecific Procedure for the Transformation of Allylic Alcohols into 1,3-Dienes
Authors: Yasuda Arata , Tanaka Shin , Yamamoto Hisashi , Nozaki Hitosi
Published: July 2006

The title synthesis involves (1) epoxidation of allylic alcohols with t-butyl hydroperoxide in the presence of vanadium catalyst followed by trimethylsilylation, (2) specific oxirane ring opening by means of diethylaluminum 2,2,6,6-tetramethylpiperidide and subsequent desilylation producing 3-ene-1,2-diols, and (3) removal of both hydroxyl groups through bromination with a mixture of phosphorus tribromide and copper(I) bromide and the successive zinc debromination. The sequence of reactions has been extended with considerable success to the preparations of β-myrcene from nerol, trans-β-ocimene from geraniol in a specific way, and α and β-farnesenes from their biological precursors. A C12 sex pheromone of red bollworm moth has been prepared efficiently by this method with cyclododecene as a starting material.
A New Synthetic Method for Some Pyrazolo[4,3-d]pyrimidines
Authors: Takei Hisashi , Yasuda Nobuyoshi , Takagaki Hidetsugu
Published: July 2006

3,7-Dihydroxy- and 3-substituted 7-hydroxypyrazolo[4,3-d]pyrimidines were synthesized from diethyl oxaloacetate and ethyl acylpyruvates via ethyl 4-amino-5-oxo-2-pyrazoline-3-carboxylate hydrochloride and ethyl 5-substituted 4-amino-3-pyrazolecarboxylates, respectively.
A New Synthetic Method for Methyl Dihydrojasmonate from a Butadiene Telomer
Authors: Tsuji Jiro , Kasuga Kazuyuki , Takahashi Takashi
Published: July 2006

Ethyl 2-acetyl-4, 9-decadienoate, easily obtained by the palladium catalyzed telomerization of butadiene with ethyl acetoacetate, was selectively hydrogenated to ethyl 2-acetyl-9-decenoate using RuCl2 (PPh3)3 as a catalyst. Deacetylation, followed by hydrolysis produced 4-decenoic acid, which was converted into acid chloride. The AlCl3-promoted cyclization gave 2-pentyl-2-cyclopentenone, from which methyl dihydrojasmonate was prepared.
Oxidation and Reduction of MoO2–MoO3 Studied by Infrared Emission Spectroscopy
Authors: Ueno Akifumi , Bennett Carroll O
Published: July 2006

A sample preparation technique was developed for the study of infrared emission spectroscopy. The emission spectrum of MoO3 showed peaks at 987 and 925 cm−1 in the temperature range of 185 through 505 °C. Peak intensities were proportional to the sample weight. The background intensity in the emission spectrum was measured at 1050 cm−1 and it was also proportional to the sample weight. In order to apply emission spectroscopy to the study of reaction kinetics, the reduction of MoO3 by H2 and the oxidation of MoO2 by O2 were chosen as model reactions. These reactions were studied at 425 to 485 °C and the activation energy for the reduction of MoO3 was 43 kcal/mol and that for the oxidation of MoO2 was 38 kcal/mol. The activation energy for the formation of the terminal Mo=O bond was, however, 71.2 kcal/mol.
Preparation and Solid-phase Thermal cis-trans Isomerization of the Mixed Bis(diamine)chromium(III) Complexes of the Type [CrX2(aa)(bb)]X·nH2O
Authors: Mitra Samiran , Yoshikuni Tadatsugu , Uehara Akira , Tsuchiya Ryokichi
Published: July 2006

The mixed bis(diamine)chromium(III) complexes trans- and cis-[CrX2(aa)(bb)]X·nH2O were prepared and characterized where X is chloride or bromide ion; aa and bb are different diamines selected from ethylenediamine (en), propylenediamine (pn) and trimethylenediamine (tn); and n is a number of 0 to 2. The cis-trans isomerization of the above complexes was investigated non-isothermally (derivatographically) and isothermally in the solid-phase. The isomerization was found to be one-way (trans-to-cis) and exothermic. The activation energies were estimated for dehydration or dehydration plus dehydrohalogenation (Ed) and isomerization (Ei. The intermediates mer-[CrBr3(en)(pn)]·2H2O and mer-[CrBr3(pn)(tn)]·2H2O were isolated during the isomerization of trans-[CrBr2(en)(pn)]Br·2H2O and trans-[CrBr2(pn)(tn)](H5O2)Br2, respectively. Bond rupture was proposed to be operative in the pathway of the isomerization.
Circular Dichroism Spectra of Some Transition Metal Complexes with (1R,2R)-1,2-Cyclopentanediamine
Authors: Goto Masafumi , Takeshita Michihiro , Sakai Tomoya
Published: July 2006

Bischelates, three isomers of dicyanocobalt(III), trans-dichlorocobalt(III), and copper(II), and a monochelate, tetracyanoferrate(II), of the title diamine were prepared, and their CD spectra were reported. Major positive components were found for Ia bands, as was to be expected for the preferred λ conformation, but minor positive components were observed for the Ib band with the trans-dianionocobalt(III) complexes. The configurational and the vicinal effects, as calculated from the CD spectra of the cis-dicyanocobalt(III) complexes, are shown to be different from those of (1R,2R)-1,2-cyclohexanediamine. The CD spectra of the Fe(II) and Cu(II) complexes are consistent with the conformational effect of the title diamine.
Autoxidation of Thujopsene in Carboxylic Acid Media. Co-preparation of Mayurone and 3-Thujopsanone
Authors: Abe Kazuo , Ito Masaaki
Published: July 2006

cis-(−)-Thujopsene has been autoxidized by perculation molecular oxygen through carboxylic acid solution, giving mayurone and 3-thujopsanone in fair yields. An investigation on the reaction conditions is described.
Branched-chain Sugars. XVII. Stereoselectivity in the Oxidation of Several Methyl 4,6-O-Benzylidene-2-C- or -3-C-methylene-α- and-β-d-hexopyranosides with m-Chloroperbenzoic Acid
Authors: Yoshimura Juji , Sato Ken-ichi , Funabashi Masuo
Published: July 2006

Stereoselectivity in the peroxy acid oxidation of methyl 4,6-O-benzylidene-3-O-methyl-2-C-methylene-α-d-ribo-hexopyranoside (1b), its 3-epimer (2b), β-anomer of 1b and 2b, methyl 4,6-O-benzylidene-2-O-methyl-3-C-methylene-α-d-arabino-hexopyranoside and its 2-epimer was examined. The results were compared with those of rigid methylenecyclohexane systems.
The Conformation of a Diastereoisomeric Pair of 2,2-Dimethyl-4-phenyl-3-pentanols
Authors: Kodama Yoshio , Nishihata Ken , Zushi Shoji , Nishio Motohiro , Uzawa Jun , Sakamoto Kazuhiko , Iwamura Hiizu
Published: July 2006

The conformations of a diastereoisomeric pair of 2,2-dimethyl-4-phenyl-3-pentanols were studied by means of 1H-NMR, 13C-NMR, IR, GC, and MS analyses. All of the results point to an unambiguous conclusion that these molecules are present dominantly in conformers where the t-butyl and the phenyl group lie close to each other. The generality of the phenomenon (favored gauche interaction) as well as the nature of the interactions involved were discussed in light of the conformational problems of the structurally related molecules. The presence of an attractive interaction (CH/π interaction) is suggested between an alkyl and a phenyl group, the possible importance of which in some dynamic phenomena (e.g., selectivities in certain reactions) has then been discussed on this basis.
Vibrational Spectra and Assignments for the Fundamental Vibrations of Imidazolidine-2-thione and -2-selenone
Authors: Dwarakanath K , Sathyanarayana D N
Published: July 2006

Infrared spectra of imidazolidine-2-thione (N,N′-ethylenethiourea, ETU) and its N,N′-deuterated (ETU-d2) and S-methylthiouronium iodides have been recorded from 4000 to 30 cm−1. Normal coordinate analyses of ETU and ETU-d2 have been made for all the fundamental frequencies, employing a Urey-Bradley potential function supplemented with valence type constants for the out of plane modes of the planar skeleton. Raman frequencies of ETU from literature have been utilised. The results of the vibrational analyses are discussed in relation to the group frequencies in structurally related molecules and frequency shifts on deuteration and S-methylation. The normal coordinate treatment is also performed for the planar vibrations of imidazolidine-2-selenone (N,N′-ethyleneselenourea, ESU) to propose assignments for ESU and so also to support the assignments of ETU.
Preparation of Fortamine and 6-epi-Purpurosamine B from Fortimicin B
Authors: Sano Hiroshi , Sakaguchi Tomoko , Mori Yasuki
Published: July 2006

Benzyl alcoholysis and hydrolysis of tetrakis-N-(benzyloxycarbonyl)fortimicin B and further transformation of the solvolysis products are described. Several derivatives of 6-epi-purpurosamine B and fortamine potentially useful for the synthesis of fortimicin analogs are presented.
A Molecular Orbital Study on the Nucleophilicity and the Electrophilicity of Free Radicals in Abstraction Reactions
Authors: Shinohara Hiroyuki , Imamura Akira , Masuda Takahiro , Kondo Masaharu
Published: July 2006

The polarities (nucleophilicity and electrophilicity) of free radicals in abstraction reactions were studied by the comparison of the stabilization energies due to delocalization of electrons (SEDE) between a radical and a substrate. The stabilization energies were calculated by the CNDO/2 method for several substrate–radical systems. For the reactions of the methyl radical with chlorinated methanes, the nucleophilicity of the radical was well interpreted by the SEDE from the radical to the substrate. Similarly, the nucleophilicity of the hydrogen atom in chlorine abstraction from chlorinated methanes was indicated by the SEDE from the hydrogen atom to the substrate. In an electrophilic reaction such as hydrogen abstraction by the methyl radical from aliphatic hydrocarbons, the activation energy was found to decrease linearly with an increase in the SEDE from the substrate to the radical. This result is consistent with the electrophilic tendency of the reaction. The SEDE calculated for the reactions of a radical with a series of substrate thus indicates the polarity of the free radical in the abstraction reactions.
An Analysis of the UV, ORD, and CD Bandshapes of the DNA–Acridine Orange Complex by the Linear Response Polarizability Theory
Authors: Ito Hirotoshi , I’Haya Yasumasa J
Published: July 2006

The linear response polarizability theory of the spectral bandshapes is applied to the numerical analysis of the UV, ORD, and CD spectra of the DNA–Acridine Orange complex by using various models of conformation. In all calculations, we make use of an infinite orders approximation for the intermonomer electronic interaction, since convergence of the Dyson-type series for the polymer polarizability tensor sometimes becomes seriously slow, in particular in such case that the transition moments of a constituent monomer such as Acridine Orange are quite large. It is found that among the various outside-stacking models, a dimer-pairs repeating sequence model newly proposed leads to reasonable results for the UV, ORD, and CD spectral bandshapes.
Asymmetric Transformation of Alanine via Optically Labile Imidazolines
Authors: Shibata Saizo , Matsushita Hajime , Kato Kunio , Noguchi Masao , Saburi Masahiko , Yoshikawa Sadao
Published: July 2006

Hydrolysis of an imidazoline derived from (S)-alanine and (S)-2-(aminomethyl)pyrrolidine afforded (R)-alanine in the optical yield of 93.8% (e.e.). The asymmetric transformation was explained on the basis of preferential crystallization of one epimer followed by epimerization of the other epimer in a solution. It was found that the epimerization was catalyzed by amines. (2S)-N-isopropyl-2-aminopropylamine was also examined as a diamine component of imidazolines.
Study of Metal-Polycarboxylate Complexes Employing Ion-selective Electrodes. II. Stability Constants of Copper(II) Complexes with Poly(acrylic acid) and Poly(methacrylic acid)
Authors: Yamashita Fumitaka , Komatsu Tsuyoshi , Nakagawa Tsurutaro
Published: July 2006

The copper(II) complex formation with poly(acrylic acid) and poly(methacrylic acid) in aqueous solution was studied by potentiometric titration employing glass and copper(II) ion-selective electrodes. The values of the equilibrium constants of the complex formation and the stability constants were estimated in various degree of neutralization. Since the concentration of free copper(II) ions could be determined by employing the copper(II) ion-selective electrode, the concentrations of two complex species, involving one and two carboxylato groups, were determined from stoichiometric equations. The equilibrium and stability constants of the complexes obtained were observed to pass through peaks with increase in the degree of neutralization. The order of magnitude of the equilibrium constant of the polyacrylate complex was larger than that of the polymethacrylate complex.
Formation of Benzyl Radicals by Pulse Radiolysis of Benzyltriphenylphosphonium Chloride in Aqueous Solutions
Authors: Horii Hideo , Fujita Shinichi , Mori Toshiaki , Taniguchi Setsuo
Published: July 2006

The reaction of benzyltriphenylphosphonium ion (PhCH2P+Ph3) with eaq− has been studied. The benzyl radical and triphenylphospine are formed by the reaction: PhCH2P+Ph3+eaq−→PhCH2·+Ph3P, with the rate constant (2.7±0.3)×1010 M−1 s−1. The benzyl radical decays in a bimolecular reaction with 2k=(2.7±0.4)×109 M−1 s−1.
Peri Interaction in Naphthalene Ketones
Authors: Kubo Masao , Sato Takeo
Published: July 2006

Peri interaction in several naphthalene ketones was investigated using the carbon-13 NMR, IR, and UV spectra. The carbonyl carbon resonances for 7H, 14H-cycloocta[1,2,3-de:5,6,7-d′e′]dinaphthalene-7,14-dione and its 7-oxa analog were found to be shifted upfield by 27 and 24 ppm respectively compared with those of model compounds. The anomalous shift for the former was attributed to π-orbital compression, which inhibited the polarization of carbonyl groups because of a forced parallel geometry, while the latter was attributed to field effects. The conclusion was supported by UV and IR data.
A New Method for the Synthesis of 2-Substituted 2-Buten-4-olide via α-Substituted β-Phenylthio-γ-butyrolactone
Authors: Watanabe Mikio , Shirai Kozo , Kumamoto Takanobu
Published: July 2006

The addition reaction of lithium benzenethiolate to 2-buten-4-olide in the presence of aldehydes and ketones afforded α-substituted β-phenylthio-γ-butyrolactones (4a–f). The dehydrosulfenylation of 4a–d proceeded smoothly to give 2-substituted 2-buten-4-olide by the reflux of α-substituted β-phenylsulfinyl-γ-butyrolactone, which was prepared by the oxidation of 4a–d, in the presence of triethylamine.
The Crystal and Molecular Structure of (±)-2-Methylamino-4,5-bis(p-chlorophenyl)-4-hydroxy-4H-imidazole
Authors: Takayanagi Hiroaki , Ogura Haruo , Matsuzaki Keinosuke , Kitajima Koji , Nishimura Tamio
Published: July 2006

The crystal and molecular structure of (±)-2-rnethylarnino-4,5-bis(p-chlorophenyl)-4-hydroxy-4H-imidazole has been determined by the single-crystal X-ray diffraction method. The crystals are monoclinic with space group P21/c, cell dimensions: a=14.872(5), b=9.216(7), c=12.945(11) Å, β=99.53(5)°, and Z=4. The structure was determined by the symbolic addition method and refined by the least-squares method to give the final R factor of 0.072 for 1616 non-zero reflections.
Monolayer Studies of Chiral and Racemic 12-Hydroxyoctadecanoic Acids
Authors: Tachibana Taro , Yoshizumi Tokiko , Hori Kayako
Published: July 2006

The monolayer properties of chiral and racemic 12-hydroxyoctadecanoic acids (12HOA) have been studied. Both acids showed, in each pressure-area isotherm, a pressure plateau. This was interpreted as a two-dimensional phase transition region: from the expanded monolayer composed of bent chain molecules with both the hydroxyl and carboxyl groups attached to the water surface, to the condensed monolayer composed of straight chain molecules oriented steeply to the water surface. It was suggested by measuring infrared spectra of the collapsed films and the built-up films that the condensed monolayer involves intermolecular hydrogen bonds. Differences between (R)- and dl-12HOA were found in the plateau pressure and its temperature dependence leading to the transition energy. These results were attributed to the formation of a recemic molecular compound during condensation of monolayers of dl-12HOA, prior to collapse, followed by a different manner of hydrogen bonding. Electron microscope observation gave strong evidence for the two-dimensional racemic compound formation. On the basis of these results and the X-ray diffraction data, molecular packing models in the condensed monolayers were proposed.
Polarographic Determination of Bismuth, Copper, Iron(III), Palladium, and Uranium(VI) after Extraction into Molten Naphthalene with Oxine
Authors: Puri B K , Gautam Mamta , Fujinaga Taitiro
Published: July 2006

A rapid extraction-polarographic method has been developed for the direct determination of bismuth, copper, iron(III), palladium, and uranium(VI) extracted into the organic phase. Oxinates of metals were extracted into molten naphthalene at different pH values. With lowering of temperature, naphthalene separated out as a solid containing the metal oxinates. The solid mass was dissolved in DMF and the polarograms were recorded in the presence of a suitable supporting electrolyte. The metal oxinates give well defined waves. The relation between diffusion current and concentration is linear over a wide range of concentration with an average relative error not more than 1.05%. Interferences of various ions have been studied of the anions studied, only EDTA interfered in the extraction of bismuth, copper, iron(III), and uranium(VI). Of the cations studied, palladium interfered in the determination of bismuth, copper, iron(III), and uranium(VI). However, the intereference was eliminated by carrying out extraction first at low pH. In the determination of bismuth only copper interfered but its interference can also be eliminated as in the case of palladium. In the case of copper determination, only iron(III) interfered. In the determination of iron, copper interfered but interference can be eliminated by using a suitable masking agent. The determination of palladium and uranium(VI) is free from all interferences.