bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and Stereochemistry of Bis(ethylenediamine)cobalt(III) Complexes with Selenium Donor Atom
Authors: Konno Takumi , Okamoto Ken-ichi , Hidaka Jinsai
Published: July 2006

Five optically active cobalt(III) complexes of [Co(bidentate-N,Se)(en)2] type were prepared; here bidentate-N,Se denotes 2-aminoethaneselenolato (aes), 2-aminoethaneselenenato (aesee), 2-(methylseleno)ethylamine (mseea), 2-(ethylseleno)ethylamine (eseea), and 2-(benzylseleno)ethylamine (bseea). These complexes were characterized from their absorption, CD and 1H NMR spectra. Of these complexes, the crystal structure of (+)500CD-[Co(mseea)(en)2](ClO4)3 was determined by the X-ray diffraction method. The red plate crystal was orthorhombic, space group P212121, a=12.220(15), b=19.224(7), c=8.977(11) Å, Z=4, and the final R value was 0.087. The coordinated selenium atom takes the (R) configuration for the Λ isomer. The absorption and CD spectra of the five complexes are discussed in comparison with those of the corresponding cobalt(III) complexes containing a coordinated sulfur atom.
Preparation and Characterization of Cobalt(III) Complexes with S,S-Bridge R,S-Sexidentate-N2,S2,O2 Type Ligands. Crystal Structure of (+)560CD-((2R,9S)-Diamino-3,3,8,8-tetramethyl-4,7-dithia-1,10-decanedioato)cobalt(III) Ion
Authors: Kanesaka Mikako , Okamoto Ken-ichi , Nomoto Masayo , Hidaka Jinsai
Published: July 2006

[Co(R,S-sexidentate-N2,S2,O2)] and [Co(R-terdentate-N,S,O)(S-terdentate-N,S,O)] type complexes, including the title complex cation, [Co(R,S-ebp)]+, were prepared and resolved. The crystal structure and absolute configuration of the (+)560CD-[Co(R,S-ebp)]+ isomer were determined by X-ray diffraction. The complex cation has an [S] configuration. The R,S-ebp coordinates as a sexidentate, of which two sulfur donor atoms take selectively R(S). The absorption and CD spectra are discussed in comparison with those of the related complexes.
Concentration Dependence of Transport Properties of Glass-forming Melts
Authors: Mahiuddin Sheik , Ismail Kochi
Published: July 2006

The Vogel-Tammann-Fulcher (VTF) equation has been derived from the Adam-Gibbs (AG) model after accounting for the empirical nature of the temperature dependence of configurational heat capacity. An expression for describing the concentration dependence of the preexponential parameter of the VTF equation and another two-parameter isothermal equation for describing such dependences of transport properties are obtained. The applicability of the newly derived equations has been verified using the data available for several hydrate melts. The present study emphasizes the view that the glass transition temperature controls the concentration dependence of transport properties of glass-forming melts.
Preparation and Characterization of [CoX2(edpp)2]+(edpp=NH2CH2CH2P(C6H5)2, X=Cl−, Br−, I−, NCO−, NCS−, N3−, NO2−) and [CoX2(en)(dppe)]+(en= NH2CH2CH2NH2, dppe=(C6H5)2PCH2CH2P(C6H5)2, X=Cl−, Br−, NCS−). Crystal Structures of trans(NCS,NCS),cis(P,P)-[Co(NCS)2(edpp)2]Br·3H2O·(CH3)2CO and cis-(NCS,NCS),trans(P,P)-[Co(NCS)2(edpp)2]-Br·CH3OH
Authors: Atoh Masamichi , Kashiwabara Kazuo , Ito Haruko , Ito Tasuku , Fujita Junnosuke
Published: July 2006

Dianionocobalt(III) complexes of the [CoX2(edpp)2]+-type (X=Cl−, Br− I−, NCO−, NCS−, N3−, NO2−) have been prepared, where edpp is (2-aminoethyl)diphenylphosphine. The corresponding [CoX2(en)(dppe)]+ complexes are rather unstable and have been obtained only for X=Cl−, Br−, and NCS−, where en and dppe denote ethylenediamine and 1,2-bis(diphenylphosphino)ethane, respectively. Except for the NCS− complex of edpp, only one geometrical isomer has been obtained for all the complexes. Two geometrical isomers of [Co(NCS)2(edpp)2]+ have been isolated, and crystal structures of trans(NCS,NCS),cis(P,P)-[Co(NCS)2(edpp)2]Br·3H2O·(CH3)2CO and cis(NCS,NCS),trans(P,P)-[Co(NCS)2(edpp)2]Br·CH3OH have been determined by X-ray analyses. The NCS− ions in these complexes coordinate to the cobalt(III) ion through their nitrogen atoms with nearly linear Co–N–C–S fragments. The Co–P distances in the isomers are similar to one another, but the average Co–NH2 and Co–NCS distances in the trans(NCS,NCS) isomer (2.010 and 1.882 Å) are longer and shorter than those of the cis(NCS,NCS) isomer (1.970 and 1.960 Å), respectively. Absorption spectra of all the complexes in solution have been recorded and the results compared with those of related dianionocobalt(III) complexes.
Noncovalent Interactions in Metal Complexes. VIII. Syntheses, Properties, and Stereoselectivities of Lanthanoid Complexes with 1-l-Menthyloxy-3-benzoylacetone
Authors: Nakamura Michio , Okawa Hisashi , Kida Sigeo , Misumi Seizo
Published: July 2006

Lanthanoid complexes with 1-l-menthyloxy-3-benzoylacetone, [Ln(l-moba)3(H2O)n] (Ln=La, Pr, Nd, Eu, Dy, Ho, Tm; n=0, 1, or 2), have been synthesized and characterized by elemental analyses, molecular weight determinations, and electronic, circular dichroism, and luminescence spectra. The molecular weight determinations suggest that the complexes are in a monomer-dimer equilibrium in nondonating solvents while they are monomeric in donating solvents. The complexes exhibit fairly intense circular dichroisms at the f-f band region, demonstrating the stereoselective formation of an enantiomer. The stereoselectivities have been discussed in terms of the intramolecular interligand CH/π-interaction operating between the phenyl and the menthyl groups of the ligands. [Eu(l-moba)3(H2O)] shows luminescence at the 5D0→7F1 and 5D0→7F2 transitions in benzene. Based on the concentration dependence of the luminescence, it is demonstrated that dimerization facilitates nonradiative relaxation and greatly reduces the quantum efficiency of luminescence.
The MCPBA-oxidation of 8H-Cyclohepta[b]thiophen-8-ones to Their 1,1-Dioxides and Further Ring-contracted Benzo[b]thiophene Derivatives
Authors: Takeshita Hitoshi , Motomura Hideshi , Mametsuka Hiroaki
Published: July 2006

Upon MCPBA-oxidation, several 8H-cyclohepta[b]thiophen-8-ones yielded the 8H-cyclohepta[b]thiophen-8-one 1,1-dioxides and their epoxides. The latters were shown to be convertible to several ring-contracted derivatives, the benzo[b]thiophene 1,1-dioxides and/or their corresponding phenol and salicylaldehyde derivatives.
Electroluminescent Properties of n-GaAs in Peroxodisulfate Solutions. Transient Behavior and Carrier Concentration Effect on Emission Spectra
Authors: Uosaki Kohei , Kita Hideaki
Published: July 2006

Electroluminescence (EL) due to band-to-band transition was observed for n-GaAs in solutions containing peroxodisulfate ions. Digital simulation shows that the observed transient current and EL intensity stimulated by negative potential pulses can be explained by assuming that the surface concentration of S2O82− was zero during potential pulses and that the EL intensity was proportional to the surface concentration of SO4\ewdot(generated by the one-electron reduction of S2O82−). Surface composition change seems to be the main reason for the relation between the potential and EL intensity. A hydrogen evolution reaction reduces the EL efficiency at relatively negative potentials. Although the potential and time had no observed effect on the shape of the EL spectra, the carrier concentration affected the peak position and the full width at half maximum (FWHM) of the EL spectra. For greater carrier concentrations, the wavelength of the EL peak became shorter and the FWHM became larger. These results agree with those reported regarding solid-state luminescence and can be explained by the filling of the conduction band states by electrons (Burnstein-Moss shift).
Enhanced Circular Dichroism and Phase Separation of Azobenzene-Containing Chiral Bilayer
Authors: Nakashima Naotoshi , Morimitsu Kozo , Kunitake Toyoki
Published: July 2006

An azobenzene-containing chiral amphiphile showed a drastic enhancement of circular dichroism (CD) due to formation of the rigid bilayer assembly. The drastic CD change was caused by phase transition of the matrix bilayer in the case of mixed bilayers with dihexadecyldimethylammonium bromide, but was caused by phase transition of the chiral component in the case of the single component bilayer. Both CD and absorption spectra of the azobenzene-containing chiral bilayer were used for detecting phase separation of mixed membranes. It was pointed out that the CD technique is widely applicable to phase separation studies.
The Structure of Liquid Water by Neutron Scattering. III. Calculations of the Partial Structure Factors
Authors: Ohtomo Norio , Tokiwano Kazuo , Arakawa Kiyoshi
Published: July 2006

A formula for obtaining partial structure factors for fluid systems composed of molecular clusters with various sizes was derived according to the theoretical procedure proposed in the preceding papers (N. Ohtomo, K. Tokiwano, and K. Arakawa, Bull. Chem. Soc. Jpn., 54, 1802 (1981): 55, 2788 (1982)). The formula was applied to calculate partial structure factors of liquid water, and from the good agreement between the calculated and observed values the pentamer–monomer mixture model for liquid water was confirmed as reasonable.
Polarized Raman and Phosphorescence Spectra of [1H4]- and [2H4]Pyrimidines
Authors: Umemoto Masayuki , Ogata Taketora , Shimada Hiroko , Shimada Ryoichi
Published: July 2006

Assignments of the out-of-plane normal vibrations of [1H4]- and [2H4]pyrimidines were reexamined through studies of the polarized Raman, time-resolved phosphorescence and polarized dark sublevel phosphorescence spectra. The vibrational analyses of the phosphorescence spectra based on their polarization behavior indicate that the appearance of the strong 0-0 and totally symmetric vibronic bands in the dark sublevel phosphorescence spectra is attributed to the distortion of the molecular structure along the b1 normal coordinates in the lowest triplet state.
Vibrational Distributions of CO+ (A) Produced from the Charge-transfer Reactions of Ne+ and He+ with OCS at Thermal Energy
Authors: Sekiya Hiroshi , Tsuji Masaharu , Nishimura Yukio
Published: July 2006

The Ne++OCS and He++OCS charge-transfer reactions have been studied by emission spectroscopy in a flowing afterglow. The relative vibrational populations of CO+(A2Π) were determined by observing the CO+(A2Π–X2Σ+) emission system produced from the above reactions. The populations decrease approximately exponentially with the vibrational quantum number.
Photoinduced Potential Changes across Poly(vinyl chloride)/Crown Ether Membranes. Membrane Potential in the Presence of Alkaline Earth Metal Cations
Authors: Anzai Jun-ichi , Sasaki Hiroshi , Ueno Akihiko , Osa Tetsuo
Published: July 2006

The potential change across poly(vinylchloride)/crown ether membrane was induced by photoirradiation in the presence of alkaline earth metal cations. The photoresponse of the membrane potential depended markedly on the kind and concentration of the cation species, the magnitude of the potential shift lying in the order of Mg2+>Ca2+≈Sr2+>Ba2+.
Preparatively Useful Method for the Synthesis of Diels-Alder Adducts between Furan and Methyl Acrylate
Authors: Kotsuki Hiyoshizo , Asao Kazuhiko , Ohnishi Hiroyuki
Published: July 2006

The Diels-Alder adducts of furan with methyl acrylate were successfully prepared by two methods on a preparative scale. The BF3·OEt2-catalyzed reaction of furan with methyl acrylate gave a 7:3 mixture of endo and exo adducts in 75.7% yield. When acryloyl chloride was used as a dienophile, after esterification with methanol, a 3:7 mixture of the same adducts was obtained in 76.5% overall yield.
Photoreaction of S-Butyl 3-Methoxy-2-butenethioate. Competitive 1,5-Methyl Migration and O-Demethylation
Authors: Hasegawa Tadashi , Iwasaki Kazuhiko , Yoshihara Nobutoshi
Published: July 2006

Irradiation of S-butyl (Z)-3-methoxy-2-butenethioate (1Z) gave the 1,5-methyl migration product 2 and the O-demethylation product 3. The photo-1,5-methyl migration occured competitively with the O-demethylation from the π, π* excited triplet state of 1Z. The migration product 2 underwent the secondary photoreaction to 3 in a nondegassed benzene solution.
Efficient Preparation of 3-Alkyl(or Aryl)thio-1(or 2)-propenyl p-Tolyl Sulfones
Authors: Ogura Katsuyuki , Iihama Teruyuki , Takahashi Kazumasa , Iida Hirotada
Published: July 2006

Synthetic routes from 3-chloro-1-propenyl p-tolyl sulfone to 3-(p-tolylthio)-1(or 2)-propenyl p-tolyl sulfone, 3-isopropylthio-1(or 2)-propenyl p-tolyl sulfone, and 3-methylthio-2-propenyl p-tolyl sulfone were exploited.
Deoximation of Oxime O-Acetates, Oximes, and Oxime Ethers by Nonacarbonyldiiron or Pentacarbonyliron. An Electronic Effect for the N–O Bond Cleavage
Authors: Nitta Makoto , Sasaki Ichiro , Miyano Hiroyuki , Kobayashi Tomoshige
Published: July 2006

The reaction of [Fe2(CO)9] or [Fe(CO)5] with oxime O-acetates, oximes, and oxime ethers under photoirradiation or thermal conditions undergoes deoximation to give the corresponding ketones. The oxime O-acetate was found to be the most reactive class of these compounds. A proposed mechanism involves an initial complexation of the [Fe(CO)4] species to the nitrogen atom of the oxime group, and the subsequent N–O bond cleavage to give an imido complex. Then the imido complex could collapse to the corresponding ketone via an imine intermediate in protic media.
The Reductive Amination of Carbonyl Compounds Using Sodium Hydrogentelluride as a Reducing Reagent
Authors: Yamashita Masakazu , Kadokura Mamoru , Suemitsu Rikisaku
Published: July 2006

Carbonyl compounds were aminated to secondary amines in moderate yields under mild conditions using sodium hydrogentelluride as a reducing reagent.
O- and C-Perfluoroalkylations of Phenol System with (Perfluoroalkyl)phenyliodonium Triflates
Authors: Umemoto Teruo , Miyano Osamu
Published: July 2006

The reaction of FITS reagents with the phenols bearing bulky substituents at C-positions yielded O- and C-perfluoroalkylation products whose ratios were dependent on the steric bulkiness of the substituents or the perfluoroalkyl groups and the reaction temperature.
NQR of the 1 : 2 Molecular Complex of 1,4-Diazabicydo[2.2.2]octane with Chloroform
Authors: Negita Hisao , Suzuki Toshinori , Kubo Tsuneo , Maekawa Michio , Gima Shinei , Okuda Tsutomu
Published: July 2006

The 14N and 35Cl NQR and 14N spin-lattice relaxation have been studied at various temperatures on the 1 : 2 molecular complex of 1,4-diazabicyclo[2.2.2]octane (DABCO) with CHCl3. Two transitions have been observed near 123 K and 138 K. In the lowest temperature phase a minimum in the T1 was observed and attributed to the axial reorientation of DABCO molecules. The activation energy for this motion was determined to be 12.1±1.2 kJ mol−1. The electron population is discussed for the DABCO complexes with CHCl3 and CDCl3 using the Townes-Dailey treatment.
Behavior of Benzo-18-crown-6 Complexes with Alkali Metal Ions in Various Nonaqueous Solvents
Authors: Takeda Yasuyuki , Ohyagi Yoshihiko , Akabori Sadatoshi
Published: July 2006

The formation constants for 1 : 1 complexes of benzo-18-crown-6 (B18C6) with alkali metal ions and the solubility of B18C6 in various solvents were determined at 25 °C by conductometry and spectrophotometry, respectively. In general, the selectivity of B18C6 for alkali metal ions is governed primarily by the size relationship between cations and the B18C6 cavity. For a given alkali metal ion, the solvation ability of the solvent plays the most important role in determining stability sequences of the B18C6 complex in the solvents. Transfer activity coefficients of B18C6-alkali metal ion complexes were calculated. The transfer activity coefficient of the B18C6 complex from methanol to aprotic solvents somewhat varies with alkali metal ions in the B18C6 cavity. The magnitudes of the transfer activity coefficients of the B18C6 complex from acetonitrile and propylene carbonate to DMF and DMSO are determined mainly by the relative strength of the solvation ability of the former group and the latter group for the alkali metal ion in the B18C6 cavity. In methanol, due to the hydrogen bonds between ether oxygen atoms of B18C6 and methanol, the B18C6 complex is more strongly solvated than the corresponding alkali metal ion, compared to the case of the aprotic solvents.
A Study of the Charge-Discharge Characteristics of the Lithium–Polyacetylene Battery by Means of the FFT Impedance Measurement
Authors: Osaka Tetsuya , Kitai Takashi
Published: July 2006

The charge-discharge characteristics of the anion-doped lithium–polyacetylene [(CH)x] battery was investigated by means of the FFT impedance method, by which the impedance-frequency dispersion could be measured by very high speed. The charging and self-discharging of the Li–(CH)x battery were represented by the Randles-type equivalent circuit, added with the corrective term concerned with surface roughness. These processes and their doping states of the (CH)x film were readily detected by the variation in the resistive component, Rr, in the equivalent circuit. The Rr value of the self-discharge process was clearly correlated to the open-circuit voltage, Voc, regardless of the charging current; furthermore, it was strongly indicated that the self-discharge process is mainly caused by the dopant diffusion from the interface into the interior part of (CH)x films. For the discharging process, another mechanism, closely concerned with dopant diffusion, was suggested by the impedance results.
The Excited-state Absorption and Phosphorescence of Rhodium(III) Compounds at Room Temperature
Authors: Ohno Takeshi , Kato Shunji
Published: July 2006

The excited states of rhodium(III) compounds including [Rh(4,7-diphenyl-1,10-phenanthroline)3]3+ ([Rh(dp-phen)3]3+), [Rh(1,10-phenanthroline)3]3+ ([Rh(phen)3]3+), [RhCl2(dp-phen)2]+, and [RhCl2(phen)2]+, have been investigated by means of emission spectroscopy and laser photolysis spectroscopy. The transient species with the lifetime of 0.055–72 μs are identified as the triplet (π-π*) excited state of the ligand for [Rh(dp-phen)3]3+ and [Rh(phen)3]3+ and as the triplet ligand-field excited states for [RhCl2(dp-phen)2]+ and [RhCl2(phen)2]+. The molar absorption coefficients of the excited states are 9600 M−1 cm−1 at 550 nm for [Rh(dp-phen)3]3+, 2750 M−1 cm−1 at 560 nm for [RhCl2(dp-phen)2]+, 2300 M−1 cm−1 at 510 nm for [Rh(phen)3]3+, and 1600 M−1 cm−1 at 550 nm for [RhCl2(phen)2]+. The lifetime of the ligand-field excited state of [RhCl2(phen)2]+ (700 ns in acetonitrile) decreases to 55 ns in water.
Mercury- and Cadmium-photosensitized Reactions of γ-Butyrolactone
Authors: Yamamoto Shunzo , Matsuda Shuzo , Ozaki Chihiro , Takahoso Hiroshi , Nishimura Norio
Published: July 2006

The mercury- and cadmium-photosensitized reactions of γ-butyrolactone have been compared. The products obtained in the two photosensitizations were quite different. The gaseous products from the mercury-photosensitized reaction were carbon dioxide, cyclopropane, and propylene, while the products obtained in the cadmium-photosensitized reaction were carbon monoxide and ethylene. This difference suggests that the decomposition of γ-butyrolactone takes place through different intermediates in the two reactions. Possible mechanisms are discussed.
The Dispersion Stability of Colloidal Particles in Dioxane–Water Mixtures
Authors: Kandori Kazuhiko , Kon-no Kijiro , Kitahara Ayao
Published: July 2006

The dispersion stability of titanium dioxide particles and two kinds of iron(III) oxide particles in dioxane–water mixtures was studied as a function of the dielectric constant(ε=2.2–78). The sedimentation of dispersions, the adsorption of sodium 1,2-bis(2-ethylhexyloxycarbonyl)ethanesulfonate (Aerosol OT or AOT) on the particles, and the zeta potential were measured. In the absence of AOT, the dispersions of all the particles were rapidly flocculated over all of the region of the dielectric constant, and little effect of the dielectric constant on the dispersibility was observed. In the presence of AOT, however, the dispersions of all the kinds of particles used were stabilized at both the lower(ε=2.2) and higher(ε=60–78) regions of the dielectric constant by the adsorption of AOT on the particles. However, the flocculation was accelerated for all kinds of particles, and AOT molecules were not at all, or scarcely, adsorbed on the particles in the middle region of the dielectric constant(ε=10–50). This behavior of the dispersibility corresponded with the results of the dynamic light scattering of the AOT solution, which reveal the aggregation of AOT molecules at various dielectric constants. The zeta potential changed from a positive sign to a negative sign with the increase in the dielectric constant, and the isoelectric dielectric point (IED), which means a zero value of the zeta potential, appeared. The order of the values of IED among the three kinds of particles agrees with the order of the isoelectric points(IEP) of the particles. This result can, therefore, be explained by the concept of the acid-base interaction between a particle and a solvent in dioxane–water mixtures.
Convenient Syntheses of Vitamin K and Coenzyme Q by the Coupling of Grignard Reagents with Allylic Phosphate
Authors: Araki Shuki , Sato Takashi , Miyagawa Hiroyuki , Butsugan Yasuo
Published: July 2006

Convenient syntheses of vitamin K and coenzyme Q are described. Grignard coupling of polyprenyl diethyl phosphates with 1,4-dimethoxy-3-methyl-2-naphthylmagnesium bromide gave high yields of the polyprenylated hydroquinone dimethyl ethers regioselectively with the preservation of the stereochemistry. The precursors of coenzyme Q were similarly obtained by the coupling of 2,3,4,5-tetramethoxy-6-methylphenylmagnesium bromide and the polyprenyl phosphates. The synthesized (polyprenyl)hydroquinone dimethyl ethers are known to be oxidized to the biologically active quinones.
Preparation and Spectroscopic Studies of the Stereoisomers of [Co(acac)2(R1R2NCH2CH2NR3R4 or o-Phenylenediamine)]+ (R1–R4=H, CH3, or C6H5; acac=2,4-Pentanedionate ion) and Isomer Distribution at Equilibrium
Authors: Ouyang Yue , Kojima Masaaki , Fujita Junnosuke
Published: July 2006

A series of complexes of the type, [Co(acac)2L]+, where acac=2,4-pentanedionate ion and L denotes R1R2NCH2CH2NR3R4 (R1–R4=H or CH3), N-phenylethylenediamine, N,N′-diphenylethylenediamine, and o-phenylenediamine were prepared and the isomers separated. The absorption spectra and the distributions of the isomers at equilibrium were determined and the results are discussed.
Ab Initio Gradient Calculation of the Molecular Structures of Dimethyl Ether and Dimethyl Sulfide
Authors: Tsuboyama Akira , Takeshita Kouichi , Konaka Shigehiro , Kimura Masao
Published: July 2006

The molecular structures and torsional potentials of (CH3)2O and (CH3)2S have been calculated by the ab initio gradient method using a MIDI-4 basis set augumented with polarization functions. The calculations have confirmed that the molecules take the staggered-staggered conformation with C2v symmetry.
The Phosphorus-31 Nuclear Magnetic Resonance Spectra of Bis(acetylacetonato)cobalt(III) Complexes Containing Bidentate Diphosphines
Authors: Koike Yoshio , Takayama Toshio , Watabe Masatoshi
Published: July 2006

The phosphorus-31 nuclear magnetic resonance spectra of [Co(acac)2(P-P)]+(P-P=diphosphine ligand) of the Werner type were measured, and the coordination chemical shifts were compared with those of complexes studied before. The coordination chemical shifts of the five-membered chelate ring were twice as much as those of the six-membered ring.
A Facile Method for Activation of Carboxylic Acids
Authors: Murata Shizuaki
Published: July 2006

1,1′-Oxalyldiimidazole, -1,2,4-triazole, and -1,2,3,4-tetrazole were prepared in situ from oxalyl dichloride and corresponding 1H-azoles. The 1,1′-oxalyldiazoles converted carboxylic acids and their salts into 1-acylazoles.
Reactions of Trifluoromethanesulfonyl Azide with Aromatic Compounds
Authors: Kamigata Nobumasa , Yamamoto Kazutoshi , Kawakita Osamu , Hikita Kiyoyuki , Matsuyama Haruo , Yoshida Masato , Kobayashi Michio
Published: July 2006

Thermolysis of trifluoromethanesulfonyl azide in solvents composed of 1:1 mixtures of benzene and substituted benzenes gives trifluoromethanesulfonanilide and substituted trifluoromethanesulfonanilides. The isomer ratios, the total rate ratios, and the partial rate factors for the sulfonamidation have been determined. By the intramolecular and intermolecular selectivities, the reaction mechanism involving trifluoromethanesulfonyl nitrene intermediate is discussed.
A Simple Synthesis of Methyl 2,3,6- and 2,4,6-Tri-O-benzyl-α-d-mannosides
Authors: Koto Shinkiti , Takenaka Kazuhiro , Morishima Naohiko , Sugimoto Akiko , Zen Shonosuke
Published: July 2006

Cotrolled benzylation of methyl α-d-mannopyranoside with benzyl chloride and LiOH selectively gave the 2,3,6-tribenzyl ether in a 53% yield. Such a reaction using benzyl chloride and KOH afforded mainly the 2,4,6-tribenzyl ether in a 41% yield. The products were allylated and then hydrolyzed to give the corresponding 1-OH derivatives.
The Synthesis of Racemic Dihydroageratone. Efficient Demethylation by Magnesium Iodide Etherate
Authors: Yamaguchi Seiji , Sugiura Kyoichi , Fukuoka Reiko , Okazaki Kazumi , Takeuchi Mie , Kawase Yoshiyuki
Published: July 2006

2-Isopropenyl-6-methoxy-2,3-dihydrobenzofuran, prepared from m-methoxyphenol and 1,4-dibromo 2-methyl-2-butene, was converted to racemic dihydroageratone via oxidation with selenium dioxide, the acetylation with acetic acid–trifluoroacetic anhydride, and the demethylation with magnesium iodide etherate.
Potentiometric and Calorimetric Studies on the Formation of Ethylenediamine Complexes of Copper(II) Ion in Water and Aqueous Dioxane Solutions
Authors: Ishiguro Shin-ichi , Oka Yoshihiro , Ohtaki Hitoshi
Published: July 2006

Gibbs energies (or formation constants), enthalpies and entropies of formation of ethylenediamine complexes of copper(II) ions have been determined by means of potentiometric and calorimetric titrations at 25 °C in an aqueous solution and dioxane–water mixtures (dioxane contents are 0.1 and 0.2 mole fractions, which correspond to 35.2 and 55.0% w/w, respectively), all containing 3 mol dm−3 LiClO4 as a constant ionic medium. The thermodynamic quantities of the reactions CuLn−12++L=CuLn2+ (L=ethylenediamine and n=1 and 2) determined in the solutions were as follows: ΔG1°=−65.0 kJ mol−1 (dioxane content: 0.0 mole fraction), −66.8 kJ mol−1 (0.1 mole fraction), and −68.8 kJ mol−1 (0.2 mole fraction); ΔG2°=−56.9 kJ mol−1 (0.0), −58.8 kJ mol−1 (0.1), and −61.1 kJ mol−1 (0.2); ΔH1°=−67.7 kJ mol−1 (0.0), −68.6 kJ mol−1 (0.1), and −66.7 kJ mol−1 (0.2); ΔH2°=−71.0 kJ mol−1 (0.0), −70.2 kJ mol−1 (0.1), and −68.8 kJ mol−1 (0.2); TΔS1°=−2.7 kJ mol−1 (0.0), −1.8 kJ mol−1(0.1), and 2.1 kJ mol−1 (0.2); TΔS2°=−14.1 kJ mol−1 (0.0), −11.4 kJ mol−1(0.1), and −7.7 kJ mol−1 (0.2). In any solvent examined the enthalpies contribute predominantly to the Gibbs energies. On the other hand, for a given complex with varying solvent compositions, the entropies mainly contribute to the change in the Gibbs energies of the complex formation reactions. With an increase in the dioxane content of the solvent, the Gibbs energies of the complex formation reactions become more negative, while the enthalpies of the reactions remain practically unchanged or even become less negative. Consequently, the entropies of the reactions increase with increasing dioxane content of the solvent, which is explained in terms of weakening of the hydrogen-bonded structure of water in the bulk solvent by the addition of dioxane.
Preparation and Spectral Behavior of Polyoxadithia[n]ferrocenophanes and Their Silver(I) Nitrate Complexes
Authors: Sato Masaru , Kubo Masao , Ebine Seiji , Akabori Sadatoshi
Published: July 2006

Polyoxadithia[n]ferrocenophanes and polyoxatetrathia[n.n]ferrocenophanes were prepared by treatment of 1,1′-ferrocenedithiol with α,ω-dibromo polyethers. The ferrocenophanes formed efficiently a complex with a silver ion, but not with alkali and alkali-earth metal ions. The spectral data of the silver ion-complexed ferrocenophanes suggested the presence of a partial electron-transfer interaction between the iron atom and the complexed silver ion.
Mechanism of Formation of α,β-Unsaturated Esters in the Reaction of Ethyl Mercaptoacetate Dianion with Carbonyl Compounds
Authors: Matsui Syuichi
Published: July 2006

Dianion derived from ethyl mercaptoacetate undergoes aldol type reaction with a carbonyl compound to give an adduct, which exhibited low diastereoselectivity. However, the adducts obtained by the reaction with a variety of aldehydes were subsequently treated with ethyl chloroformate in the presence of trivalent phosphorus compound to give (E)-isomers of α,β-unsaturated esters in high yields with greater than 85% stereoselectivity regardless of the stereochemistry of the diastereomers of the adducts. The stereochemical mechanism and application of this reaction were studied in detail.
N-Hydroxy Amides. I. Synthesis of N-Benzyloxy and N-Hydroxy Peptides via Polymerization of N-Benzyloxy Dl-α-Amino Acid N-Carboxy Anhydrides
Authors: Shimizu Kazuyuki , Hasegawa Masayoshi , Akiyama Masayasu
Published: July 2006

Polymerization of N-benzyloxy Dl-α-amino acid N-carboxy anhydrides (N-benzyloxy-NCAs) has been carried out in benzene for 30 d with cyclohexylamine as initiator. The N-benzyloxy-NCAs of glycine, alanine, 2-aminobutyric acid, and leucine give the corresponding polymers in good yields, while the starting material is recovered from those of valine and phenylalanine. The different behavior in the polymerization is discussed in terms of steric crowding. Catalytic hydrogenation of the N-benzyloxy polymers produces poly(N-hydroxy peptide)s. Complex formation of these polymers with iron(III) has been examined. Among the polymers, poly(N-hydroxyalanine) is further converted into poly(N-acetoxyalanine), which acts as an acyl active polymer. Treatment of poly(N-benzyloxyalanine) with B(CF3CO2)3 gives 1,4-dihydroxy-3,6-dimethyl-2,5-piperazinedione.
The Carbon-13 NMR Spectra and Electronic Structure of 3H-Phenothiazin-3-one and Its Methyl Derivatives
Authors: Hasegawa Kan-ichi , Ueno Yoshio
Published: July 2006

The 13C NMR chemical shifts of 3H-phenothiazin-3-one (1) and eleven of its methyl derivatives are reported. The effect of including sulfur 3d orbitals is discussed in relation to the 13C chemical shifts. The chemical shifts of 1 can be explained in terms of both the successive polarization of the long π-conjugated framework promoted by the carbonyl group and the contribution of the sulfur d-orbitals. The 13C chemical shifts gave a better correlation with the CNDO/2 π- and total electron densities calculated by means of the sp-basis set than by means of the spd-basis set, but an improved correlation was obtained by reducing the extent of d-orbital participation on sulfur. From the correlation of the 13C chemical shifts with the CNDO/2 sp π- and the total electron densities of all the carbons of 1 and monomethyl derivatives, the proportionality constants of −300 and −180 ppm/e respectively were obtained.
Preparation of S,S-Diphenylsulfilimines, -sulfoximines, and -N-(p-tolylsulfonyl)sulfonediimines N-Substituted with Sulfur Groups of Different Oxidation States
Authors: Akutagawa Kunihiko , Furukawa Naomichi , Oae Shigeru
Published: July 2006

S,S-Diphenyl-N-(p-tolylthio)-, -N-(p-tolylsulfinyl)-, -N-(p-toluenesulfinimidoyl)-, -N-(p-tolylsulfonyl)-, and -N-(p-toluenesulfonimidoyl)sulfoximines have been synthesized either by sulfenylation, sulfinylation, sulfinimidoylation, sulfonylation, and sulfonimidoylation or by oxidation of the N-substituted sulfoximines with sulfur groups of lower oxidation states, i.e., the N-sulfenylated sulfoximine. Similar attempts have been made on similarly substituted sulfonediimines. Sulfenylation and sulfonylation of N-unsubstituted N-(p-tolylsulfonyl)sulfonediimine were unsuccessful but its sulfinylation underwent nicely. An attempt to disulfonylation of the N,N′-unsubstituted sulfonediimine ended up in the monosulfonylation. N,N′,-bis(p-Tolylsulfonyl)sulfonediimine was successfully prepared by oxidation of the N-(p-tolylsulfinyl)-N′-(p-tolylsulfonyl)sulfonediimine with m-chloroperbenzoic acid.
N-(Phenylsulfonyl)- and N-Methyl-N-(phenylsulfonyl)benzohydrazonoyl Azides. Thermally Induced Cyclization to Tetrazoles and Decomposition to Benzonitriles
Authors: Ito Suketaka , Tanaka Yumo , Kakehi Akikazu
Published: July 2006

N-(Phenylsulfonyl)- and N-methyl-N-(phenylsulfonyl)benzohydrazonoyl azides, prepared from the corresponding hydrazonoyl chlorides and sodium azide, undergo the cyclization to 5-phenyl-1-(phenylsulfonylamino)-1H-tetrazoles together with the competitive decomposition to benzonitriles and the Curtius-type rearrangement leading to semicarbazides when heated in benzene under reflux. The tetrazole formation of hydrazonoyl azides may be characteristic of such hydrazonoyl azides as those carrying an N-sulfonyl substituent, the strong electron-withdrawing nature of which probably promotes the cyclization.
Reactions of 2,3,5-Tri-O-benzoyl-d-ribofuranosyl Acetate with Enol Silyl Ethers Catalyzed by Tin(IV) Chloride. Regiochemical Features
Authors: Yokoyama Yayoi S , Inoue Tan , Kuwajima Isao
Published: July 2006

In condensation reactions of 2,3,5-tri-O-benzoyl-d-ribofuranosyl acetate with various kinds of enol silyl ethers in the presence of tin(IV) chloride, the acetate behaves as an ambident electrophile to give two types of products arising from nucleophilic attack of the enol ether on C-1 carbon of the ribose derivative and on carbonyl carbon of 2-benzoyloxyl group, depending remarkably on the enol silyl ethers.
Studies on Salt Hydrates for Latent Heat Storage. V. Preheating Effect on Crystallization of Sodium Acetate Trihydrate from Aqueous Solution with a Small Amount of Sodium Pyrophosphate Decahydrate
Authors: Wada Takahiro , Matsunaga Koji , Matsuo Yoshihiro
Published: July 2006

Influences of preheating temperature and time were studied on the crystallization of CH3CO2Na·3H2O from three kinds of CH3CO2Na aqueous solutions, whose concentrations were 58.0, 60.3, and 62.8 wt% and which contained a small amount of crystal nucleation catalyst, Na4P2O7·10H2O. In 60.3 wt% aqueous solution (CH3CO2Na·3H2O), the nucleation catalyst begins to get deactivated by preheating at about 81 °C, higher by 23 °C than the melting point of CH3CO2Na·3H2O. The temperature at which the catalyst begins to get deactivated is raised with increasing CH3CO2Na concentration of the solution; thus, in 62.8 wt% CH3CO2Na aqueous solution, the catalyst begins to get deactivated at 85 °C. One hundred samples, each consisting of 8 g of 60.3 wt% CH3CO2Na aqueous solution and 0.16 g of Na4P2O7·10H2O, all crystallized on cooling to 40 °C, even after they had been preheated at 80 °C for 39 h. These results are explained on the basis of the crystalline adsorption model proposed by Richards.
Studies on Salt Hydrates for Latent Heat Storge. VI. Preheating Effect on Crystallization of Sodium Acetate Trihydrate from Aqueous Solution with a Small Amount of Disodium Hydrogenphosphate
Authors: Wada Takahiro , Matsuo Yoshihiro
Published: July 2006

With particular reference to the use of Na2HPO4 as nucleation catalyst for crystallization of CH3CO2Na·3H2O, influences of preheating temperature and time were studied on the crystallization of CH3CO2Na·3H2O from three kinds of CH3CO2Na aqueous solutions, whose concentrations were 58.0, 60.3, and 62.8 wt%. In 60.3 wt% aqueous solution (CH3CO2Na·3H2O), the nucleation catalyst begins to get deactivated by preheating at 81 °C. The temperature at which the catalyst begins to get deactivated is slightly raised with increasing CH3CO2Na concentration of the solution. The results obtained are compared with those previously reported on the use of Na4P2O7·10H2O as nucleation catalyst, and are discussed on the basis of the crystalline adsorption model.
Kinetic Studies of the Polyiodide Complex Formation in the Iodine–Iodide Solutions
Authors: Sano Takayuki , Hori Hiroka , Yamamoto Masako , Yasunaga Tatsuya
Published: July 2006

A relaxation obviously different from that due to the triiodide complex formation was observed by the temperature-jump experiments in the iodine–iodide solution. On the basis of the dependences of the relaxation time on the concentration of iodine and iodide and on the temperature, the relaxation was assigned to the complex formation of I62−. The rate constants of the reaction were estimated to be 2.2×105 M−1 s−1 and 5.3×105 s−1 for forward and backward processes, respectively.
Determination of the Vapor Pressures of Cesium Fluoride and Cesium Chloride by Means of Surface Ionization
Authors: Kawano Hiroyuki , Kenp\={o} Tsutomu , Hidaka Yoshiaki
Published: July 2006

A molecular beam of CsF or CsCl effusing from a Knudsen cell was detected with a heated rhenium filament, and the vapor pressure P (in atm) of each halide at a temperature T (in K) was found to be expressed by log10P(CsF)=(7.239±0.072)–(9883±72)⁄T for 630–830 K, log10P(CsCl)=(7.269±0.064)–(10054±66)⁄T for 640–820 K.
The Reaction of 3,5-Diphenyl-1,2,4-dithiazol-1-ium Perchlorate with Active Methylene Compounds
Authors: Shibuya Isao
Published: July 2006

The reaction of 3,5-diphenyl-1,2,4-dithiazol-1-ium perchlorate with several kinds of active methylenes gives a number of heterocycles, such as 4-hydroxy and 4-mercaptopyrimidine, pyrimidinone, and thiazole derivatives. On treatment with hydroxylamine-O-sulfonic acid, the 4-mercaptopyrimidines lead to the aminothio compounds or the isothiazolo[5,4-d]pyrimidine.
Acylations of 2-Isopropenyl-2,3-dihydrobenzofurans
Authors: Yamaguchi Seiji , Miyata Aiko , Ueno Mariko , Hase Takayuki , Yamamoto Kenichi , Kawase Yoshiyuki
Published: July 2006

Methoxy-substituted 2-isopropenyl-2,3-dihydrobenzofurans were prepared from methoxy-substituted phenols and 1,4-dibromo-2-methyl-2-butene in one-step reactions. Their acylations with acetic acid–trifluoroacetic anhydride or N-methylformanilide–phosphoryl chloride were studied.
Plastic Phase of Formylferrocene Studied by X-Ray Diffraction and Mössbauer Spectroscopy
Authors: Sato Kumiko , Iwai Makoto , Sano Hirotoshi , Konno Michiko
Published: July 2006

The structures of both the crystal and the plastic phases of formylferrocene have been determined to be orthorhombic by single-crystal X-ray diffraction. The structural change proposes a mechanism of the transition that postulates the translational molecular motion along the a-axis. Mössbauer spectra observed in the plastic phase show little fluctuation of the electric field gradient ascribed to the orientational disorder between x, y, and z axes of the molecule.
Crystal Structure and NMR Spectral Studies of Alkali Thiocyanate Complexes with Polyoxa[n]ferrocenophanes
Authors: Akabori Sadatoshi , Habata Yoichi , Sato Masaru
Published: July 2006

1H- and 13C-NMR spectra of free ligands and their alkali metal complexes with a new type of crown ethers containing a ferrocene unit have been recorded. The change of chemical shifts in 1H- and 13C-NMR spectra was attributed to an electronic field effect and a conformational change on the metal complexation, respectively. The crystal structure of the complex of 1,4,7,10,13-pentaoxa[13]ferrocenophane with sodium thiocyanate was determined by the X-ray method. The crystals are orthorhombic, space group Cccn, with a=20.579(4), b=25.622(8) c=7.606(1) Å, U=4010(2) Å3, Z=8, Dc=1.48 g cm−3. The distances between the iron atom of a ferrocene nucleus and the incorporated sodium cation and between the sodium cation and the nitrogen atom of a counter anion are 4.129 and 2.541 Å, respectively. The results suggest that the iron atom of the ferrocene does not take part directly in complex formation and that the sodium cation forms a contact ion pair with the nitrogen atom of a counter anion.
The Sodium Isotopic Exchange Rate between High-temperature Phases of Disodium Zirconium(IV) Bis(orthophosphate) and Aqueous Solutions
Authors: Inoue Yasushi , Yamada Yoshimune
Published: July 2006

A monohydrate (Phase II) and three anhydrous phases prepared by the thermal treatment (at 250, 700, and 900 °C respectively for Phases III, IV, and V) of disodium zirconium(IV) bis(orthophosphate) trihydrate were studied from the sodium isotopic exchange rate between them and aqueous solutions. In Phases III and IV, which had been sufficiently adapted in water in advance, the rate was found to be controlled by the diffusion of sodium ions along the direction perpendicular to the layers consisting of zirconium atoms and the diffusion constants, and their activation energies (for Phases III and IV, 57 and 52 kJ/mol) were evaluated. When these phases were used as dried, the rate was governed by the irreversible dissociation of sodium in the solid phases. In Phase II, used as dried, and in Phase V, used as dried and wetted, the rate was controlled by neither particle diffusion, film diffusion, nor chemical reaction alone. This behavior was attributed to the complex behavior of phase transformation as the isotopic exchange proceeded.
Stability Constants of Scandium Complexes. I. Monocarboxylate Complexes Species
Authors: Itoh Hisako , Itoh Naomi , Suzuki Yasuo
Published: July 2006

The stability constants of scandium complexes with some carboxylate ligands were determined potentiometrically at 25.0 and 40.0 °C and at an ionic strength of 0.10 with potassium nitrate as supporting electrolyte. The constants of the scandium complexes were appreciably greater than those of the corresponding lanthanoid complexes, as expected. The changes in free energy, enthalpy, and entropy for the formation of the scandium complexes were calculated from the stability constants at two temperatures.
Asymmetric Hydrogenation with Rhodium(I)–Chiral Diphosphinites. The Effect of the Dimethylamino Group of the Ligand on the Asymmetric Induction
Authors: Yatagai Masanobu , Zama Masanobu , Yamagishi Takamichi , Hida Mitsuhiko
Published: July 2006

New chiral diphosphinites were prepared starting from (+)-diethyl tartrate. The asymmetric hydrogenation of dehydroamino acids, itaconic acid and dehydrodipeptides was studied using Rh(I)-diphosphinite catalysts. In the hydrogenation of dehydroamino acid derivatives, an introducion of ω-(dimethylamino)alkyl group in the ligands did not raise the optical yield. By the use of Rh(I)-diphosphinite having 3-(dimethylamino)propyl group, the inversion of the preferred product was observed. Itaconic acid can be hydrogenated in a good optical yield (76% e.e.) by use of the diphosphinite having 2-(dimethylamino)ethyl group. The diphosphinites having ω-dimethylamino group gave high optical yields in the case of dehydrodipeptides with a chiral center. Especially Rh(I)-catalysts coordinated by diphosphinites with 4-methyl or 4-methoxyl group on the phenyl ring of the ligand gave excellent stereoselectivities (more than 98% d.e.) in the case of Ac–ΔPhe–(S)-Phe–OH. The effect of these new chiral diphosphinites on the asymmetric hydrogenation of dehydroamino acids, itaconic acid and dehydrodipeptides was discussed in terms of the stereocontrol induced by electrostatic interaction between the dimethylamino group of the ligand and the substrate and by the steric interaction between the ligand and the substrate.
Initial Process of Photo-oxidation of Ethanol by Uranyl Ions in the Rigid Matrix at 77 K
Authors: Harazono Toshie , Sato Shin , Fukutomi Hiroshi
Published: July 2006

ESR spectra of radicals produced in the uranyl ion-photosensitized decomposition of ethanol have been measured in the rigid matrix at 77 K. At high concentrations of uranyl ions (>1 mol dm−3), methyl radicals were observed. With decreasing concentrations of uranyl ions, CH3\dotCHOH radicals became important, as expected from the previous studies. This result suggests that the charge transfer mechanism is important in the ethanol rigid matrix, although the hydrogen atom abstraction mechanism is accepted as the main initial process.
Conformational Studies of Neopentyl- and Trimethylsilylmethyl-substituted Germyl Radicals by Electron Spin Resonance
Authors: Mochida Kunio
Published: July 2006

Conformational analyses of a series of neopentyl- and trimethylsilylmethyl-substituted germyl radicals by electron spin resonance (ESR) were investigated on the basis of the modified cos2θ rule. Dimethylneopentylgermyl radical has the conformations with the neopentyl group rotating freely. On the other hand, dimethyl(trimethylsilylmethyl)germyl radical has the preferred conformations with trimethylsilylmethyl group eclipsing with the singly occupied orbital on a germanium atom. The ESR spectra of dineopentylmethylgermyl and bis(trimethylsilylmethyl)methylgermyl radicals showed the existence of two kinds of methylene protons due to the nonplanar geometries and the slow inversion of these germyl radicals. Conformations of trineopentylgermyl and tris(trimethylsilylmethyl)germyl radicals are also discussed.
Lithium Salt Effects on Extractions of 15-Crown-5, 18-Crown-6, or Their Silver(I) Complexes as Picrates
Authors: Hasegawa Yuko , Nakano Takahisa , Odori Yoshihiro , Ishikawa Y\={u}k\={o}
Published: July 2006

The extractions of 15-crown-5, 18-crown-6, or their silver(I) or lithium(I) complexes as picrates from lithium salt solutions into chloroform have been studied at 25 °C. The extractions of these crown ethers were impaired by an increase in the lithium perchlorate or nitrate concentration. A small salting-out effect was observed in the presence of lithium chloride. The extraction of silver(I) was also impaired by the addition of lithium perchlorate or nitrate. In the lower-concentration region of the lithium salts, the extraction of silver(I) was affected more markedly than that of crown ether itself.
A Synthetic Route to the Morphan Ring System by Skeletal Transformation of Norbornadiene
Authors: Inoue Hiroo , Origuchi Toshiki , Umano Katsumi
Published: July 2006

The morphan skeleton was prepared from 2-phenylsulfonyl-2-azabicyclo[3.2.1]oct-6-ene (2), derived from norbornadiene, through the addition of dichlorocarbene to the monoene 2 and the subsequent thermal isomerization of the adduct obtained. The isomerization products, 2-phenylsulfonyl-6,7-dichloro-2-azabicyclo[3.3.1]non-7-ene and 2-phenylsulfonyl-7,8-dichloro-2-azabicyclo[3.3.1]non-6-ene, which are mutually convertible in the presence of lithium chloride, were converted into various morphans by reductive dechlorination and alkylation. Furthermore, the 6,7-pyridazino-annelated morphan was synthesized by the cycloaddition of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate to 2-phenylsulfonyl-2-azabicyclo[3.3.1]non-6-ene.
Asymmetric Hydrogenation of Dehydrodipeptides with Rhodium(I)–Chiral Diphosphinites. Selective (S,S)- and (R,R)-Product Formation by Double Asymmetric Induction
Authors: Yatagai Masanobu , Yamagishi Takamichi , Hida Mitsuhiko
Published: July 2006

In the hydrogenation of dehydrodipeptides, the effect of chiral center of the substrate ((S) or (R)) on the asymmetric induction was examined using the catalysts of Rh(I)–chiral diphosphinite containing pyrrolidine moiety (POP). The catalysts with POP’s having the ω-(dimethylamino)alkyl group indicated an extremely large double asymmetric induction to give (S,S)- or (R,R)-product in high stereoselectivities, depending on the chiral center of the substrates. This result was ascribed to the electrostatic interaction between the ligand and substrate. POP’s without ω-(dimethylamino)alkyl group gave (R,R)-product for (R)-substrate in a high stereoselectivity by the steric effect between the ligand and substrate, while for (S)-substrate, (S,S)-product was obtained in a low stereoselectivity.
Studies on the Electronic Absorption Spectra of Some Selected Furan Derivatives. Molecular Orbital Calculations
Authors: Abu-Eittah Rafie Hassan , Hammed Maher Mohamed
Published: July 2006

The electronic absorption spectra of three groups of furan derivatives: 2-formyl, 2-acetylfuran, and 2-furoic acid, N-(2-furylmethylene)amines and phenylfurans were investigated. The predominant conformation as well as the polarity of the molecule could be predicted from its spectrum. The investigated molecules were proved to be “all planar” configuration which led to substantial interaction between the electronic states of the subsystems. The preferred conformations of N-(2-furylemthylene)methylamine and N-(2-furylemthylene)aniline were predicted with the aid of molecular orbital calculations.