bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Independent Isolation of a Primary Enamine and the Tautomeric Imine
Authors: Shin Chung-gi , Masaki Mitsuo , Ohta Masaki 
Published: July 2006

Abstract
Isolation of a primary enamine and its tautomeric imine has been described and their dimerization discussed. Reduction of ethyl 3-methyl-2-nitro-2-butenoate with aluminum amalgam afforded ethyl 2-amino-3-methyl-2-butenoate (I) (enamine form), while treatment of ethyl 3-methyl-2-oxobutanoate with triphenylphosphinimine gave ethyl 2-imino-3-methylbutanoate (II) (imino form). The enamine and its tautomeric imine dimerized to give 3,6-diisopropylidene-2,5-dioxopiperazine (VII) and 2-ethoxycarbonyl-2,5-diisopropylimidazolid-4-one (IX), respectively. However, individual acylation of both the enamine and the imine gave the same acyl compound.
Mechanism and Reactivity of Hydrolysis of Aliphatic Sulfonate Esters
Authors: Mori Akira , Nagayama Masuzo , Mandai Hiroshi 
Published: July 2006

Abstract
It was shown with a five-membered sultone that the hydrolysis of aliphatic sultones in water proceeds substantially by BAL1-E1 mechanism, and that it is a nucleophilic substitution reaction caused by hydroxyl ion and water. We carried out a kinetic experiment on the hydrolysis of 1,4-butanesultone and ethyl ethanesulfonate, both in water and in water-acetone mixed solvent. It was found that these aliphatic sulfonate esters were hydrolyzed substantially by BAL1-E1 mechanism as in the case of a five-membered sultone, and in particular, ethyl ethanesulfonate was hydrolyzed by complete BAL1-E1 mechanism. The results seem to be justified by a tracer experiment with H218O. Namely, the ratios of the C–O fission to the S–O fission in 1,3-propanesultone and ethyl ethanesulfonate were 85.6:14.4 and 100:0, respectively. In strong alkaline solutions and approtic solvent-water systems, the SN2 reaction involving attack of the nucleophile on sulfur atom took place partly in sultones, but practically not in linear sulfonate esters. On the other hand, the ratio of relative reaction rates of a five-membered sultone, a six-membered sultone, and a linear sulfonate ester in water is 37:1:7. Since Ea is nearly the same for these three compounds, the contribution of strain in the molecular structure to the reactivity is small, and in consequence the above ratio seems to be attributed to ΔS\eweq.
Substituted Benzopyranopyridine and Pyrimidine Ring Syntheses by the Ternary Condensation of Ethyl Cyanoacetate, Salicylaldehyde, and Certain Aldehydes in the Presence of Ammonium Acetate
Authors: Sakurai Akio , Midorikawa Hiroshi , Hashimoto Yasuo 
Published: July 2006

Abstract
Various 1-substituted benzopyranopyridines were readily prepared by the condensation of ethyl cyanoacetate and salicylaldehyde (or 3-methoxysalicylaldehyde) with aliphatic aldehydes (propion, n-butyl, n- and isovaleraldehyde) in the presence of ammonium acetate. On the other hand, condensation with aromatic aldehydes such as benzaldehyde and o-, m-, or p-substituted benzaldehydes gave 2-aryl-benzopyranopyrimidines.
Nuclear Magnetic Resonance Study of the Effect of the Hydrogen Bond on the Internal Rotation of Biphenyls
Authors: Oki Michinori , Akashi Kageyasu , Yamamoto Gaku , Iwamura Hiizu 
Published: July 2006

Abstract
Internal rotation about the pivot bond of several biphenyl derivatives has been studied by means of the nuclear magnetic resonance technique using non-identical chemical shifts of the two methyls in the isopropyl group which is located close to the center of dissymmetry. The results with the 2-methoxy and 2-hydroxy derivatives are compared. The solvent effect is marked in 2-hydroxy derivatives. These results, together with the substituent effect, indicate that the fact that the energy of activation for rotation about the pivot bond of the 2-hydroxy derivatives is a little higher than the corresponding methyl ether may be attributed to the stabilization of the ground state resulting from the presence of intramolecular O–H···π interaction. The infrared data agree with the above conclusion.
Reactions of p-Benzoquinone Derivatives with Ethylenediamine
Authors: Asahara Teruzo , Sen\={o} Manabu , Teshirogi Takuma 
Published: July 2006

Abstract
From the reaction results of p-benzoquinone derivatives with various amino compounds, it becomes clear that chloranil reacts with ethylenediamine to afford an unexpected product. The spectroscopic analyses of the product show that this is an addition compound with some contribution of charge-transfer structures. Bromanil gives a similar product upon reaction with ethylenediamine.
A Synthesis of Thyrotropin-Releasing Factor
Authors: Inouye Ken , Namba Keiko , Otsuka Hideo 
Published: July 2006

Abstract
A procedure is given for the synthesis of thyrotropin-releasing factor (TRF), a tripeptide l-pyrogultamyl-l-histidyl-l-proline amide. Benzyloxycarbonyl(Z)-glutaminyl-histidyl-proline amide (III) is obtained as an intermediate by the coupling of Z-glutamine p-nitrophenyl ester with histidyl-proline amide which is derived from the crystalline Z-dipeptide amide. Deprotection of III and the subsequent cyclization produce TRF in a moderate yield. Compound III and the corresponding Nα-acetyl derivative have little or no TRF activity.
Cyclic Acetylenes. XI. The Syntheses of p,p′-Bridged Cyclic Tolans by the Fritsch-Buttenberg-Wiechell Rearrangement
Authors: Ando Takashi , Nakagawa Masazumi 
Published: July 2006

Abstract
In order to ascertain the effect of ring strain on the electronic spectra of cyclic acetylenes, a series of p,p′-bridged cyclic tolans (Vn, n=11, 12, 13, 14, and 18) has been synthesized. It was found that the increasing ring strain exerted an appreciable hypochromic effect and also caused a slight bathochromic shift of the absorption band. The bathochromic shift observed in the p,p′-bridged cyclic tolans (Vn) forms a contrast with the hypsochromic shift observed in the strained o,o′-bridged cyclic diphenyldiacetylene (VI, n=3).
The Crystal Structure of Bis(pyridine-2-acetamide)copper(II) Perchlorate
Authors: Sekizaki Masao , Marumo Fumiyuki , Yamasaki Kazuo , Saito Yoshihiko 
Published: July 2006

Abstract
The crystal structure of bis(pyridine-2-acetamide)copper(II) perchlorate, Cu(paaH)2(ClO4)2, was determined from three-dimensional X-ray photographic data and refined by block-diagonal least-squares methods, using 1698 independent reflections to give R=0.12. The crystals are monoclinic with a space group of C2/c. There are four formula units in a unit cell with dimensions of: a=10.957, b=12.178, c=15.566 Å, and β=108.7°. The complex is centrosymmetric and square-planar, with two ligand molecules coordinating to the copper atom in trans positions through the amide-oxygen and the ring-nitrogen atoms. Two perchlorate ions coordinate weakly to the central copper atom through one of the four oxygen atoms from the top and bottom of the plane containing copper, amide-oxygen, and ring-nitrogen atoms.
The Effect of Benzene on the Reaction of the Recoil Bromine Atom with Ethyl Bromide
Authors: Shiokawa Takanobu , Sato Toshiro , Kondo Kenjiro 
Published: July 2006

Abstract
An attempt was made to estimate the effect of benzene on the recombination reactions of the recoil bromine atoms activated by the 81Br(n,γ)82mBr\oversetI.T→82Br and 81Br(n,2n)80mBr reactions in ethyl bromide and benzene mixtures. It seems to be reasonable to conclude, from the consideration of the parent yield, that the reactions leading to the formation of parent molecules in the thermal and high-energy regions can be classified into two reaction types. Judging from the results of the 81Br(n,γ)82mBr\oversetI.T→82Br reaction, approximately 53% of the parent yield from the high energy reactions in the pure ethyl bromide system is formed through the de-excitation process of the excited ethyl bromide labelled by the direct substitution reaction of the energetic recoil atom, while 47% is formed by the reaction of the recoil atom with ethyl radicals in the cage. The reaction of ethylene with hydrogen bromide, which is produced by the decomposition of the labelled excited ethyl bromide, contributes about 51% of the parent yield from the thermal energy reaction; the rest is formed by the other thermal reactions. Furthermore, no essential difference was observed between the recombination reactions of the recoil 82Br and 80mBr atoms produced by the 81Br(n,γ)82mBr\oversetI.T→82Br and 81Br(n,2n)80mBr reactions respectively.
The Crystal Spectra of Molecular Compounds of 1,6-Diaminopyrene
Authors: Amano Takako , Kuroda Haruo , Akamatu Hideo 
Published: July 2006

Abstract
Polarized absorption spectra were observed on the single crystals of molecular compounds which involve 1,6-diaminopyrene as electron donor and p-chloranil, p-bromanil, p-iodanil, and tetracyano-p-quinodimethane as electron acceptor. It is shown that, in spite of the low ionization potential of diaminopyrene 6.56 eV, its solid molecular compounds with chloranil, bromanil, and iodanil are of non-ionic type, and their crystal spectra exhibit the general features characteristic of a typical charge-transfer molecular compound composed of neutral molecules. The diaminopyrene-TCNQ, compound was found to be of ionic type. Although the bromanil and iodanil compounds of diaminopyrene exhibit two charge-transfer bands, in the region below 10 kK and at about 20 kK respectively, the chloranil compound does not show the near-infrared charge-transfer band corresponding to the charge transfer from the highest occupied orbital of the donor to the lowest vacant orbital of the acceptor. A discussion is given for this phenomenon from the overlap between the donor and acceptor orbitals.
Cyclic Acetylenes. XII. The Syntheses of o,p′-Bridged Cyclic Tolans by the Fritsch-Buttenberg-Wiechell Rearrangement
Authors: Kataoka Mutsuo , Ando Takashi , Nakagawa Masazumi 
Published: July 2006

Abstract
The polymethylene ether derivatives of o,p′-dihydroxydiphenvlacetylene (VIIn, n=7,8,9,10,11 and 12) have been synthesized by the Fritsch-Buttenberg-Wiechell rearrangement. The electronic, infrared, and NMR spectra of VIIn were examined. It was observed that the increasing ring strain had a hypochromic effect, with a hypso-chromic shift of the long-wavelength band in the electronic spectra of VIn making a contrast with the bathochromic shift in the strained p,p′-bridged cyclic tolans.
The Electronic Spectra of the Anion Radical Salts Derived from 2,3-Dicyano-1,4-benzoquinone and 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone
Authors: Iida Yôichi 
Published: July 2006

Abstract
The anion radical salts derived from 2,3-dicyano-1,4-benzoquinone and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone were prepared. The absorption spectra in an acetonitrile solution and the solid-state spectra were examined for these anion radical salts. Unlike the absorption spectra in solution, in the solid-state spectra strong charge-transfer bands appeared and there were blue-shifts of the high-energy bands. These spectroscopic features were discussed on the basis of the charge-transfer interaction between the anion radicals. The solid-state properties of these salts were compared with those previously investigated for the anion radical salts of the halogen-substituted p-benzoquinones.
Multidentate Ligand Substitution Reactions. XII. Substitution Reactions of the Nickel(II)-nitrilotriacetate Complex with Diethylenetriaminepentaacetic Acid in the Presence of Ethylenediamine and of the Nickel(II)-N-(2-hydroxyethyl)-iminodiacetate Complex with Ethylenediaminetetraacetic Acid and Cyclohexane-1,2-diamine-N,N,N′,N′-tetraacetic Acid
Authors: Kodama Mutsuo , Karasawa Sadatsugu , Watanabe Toshiyuki 
Published: July 2006

Abstract
The substitution reactions of the nickel(II)-nitrilotriacetate complex with diethylenetriaminepentaacetic acid in the presence of ethylenediamine and of the nickel(II)-N-(2-hydroxyethyl)-iminodiacetate complex with ethylenediaminetetraacetic acid and cyclohexane-1,2-diamine-N,N,N′,N′-tetraacetic acid were studied by employing the polarographic method. In the presence of ethylenediamine, the reaction of the nickel(II)-nitrilotriacetate complex with diethylenetriaminepentaacetic acid was found to proceed through the following four pathways:
(Remark: Graphics omitted.)
where X3− and Z5− denote completely-deprotonated nitrilotriacetate and diethylenetriaminepentaacetate anions respectively, and A°, ethylenediamine. By comparing the rate constants of the substitution reactions of the nickel(II)-nitrilotriacetate and ethylenediamine complexes with their dissociation rate constants, the structure of the reaction intermediate was determined. From the concentration dependence of the reaction rate, the reactions of the nickel(II)-N-(2-hydroxyethyl)-iminodiacetate complex with ethylenediaminetetraacetic acid and with cyclohexane-1,2-diamine-N,N,N′,N′-tetraacetic acid were concluded to proceed through the following two reaction pathways:
(Remark: Graphics omitted.)
where X2− and Y4− mean completely-deprotonated N-(2-hydroxyethyl)-iminodiacetate and ethylenediaminetetraacetate or cyclohexane-1,2-diamine-N,N,N′,N′-tetraacetate anions. From a comparison of the rate constants for the reaction of the N-(2-hydroxyethyl)-iminodiacetate complex with those for the corresponding reaction of the iminodiacetate complex, it was found that the hydroxyethyl group in the N-(2-hydroxyethyl)-iminodiacetate anion rather accelerates the dissociation of the N-(2-hydroxyethyl)-iminodiacetate anion from the nickel(II) ion.
Studies on Heteroaromaticity. XLIV. Reactivities of Benzoyl Cyanide N-Oxide and Some Derivatives Therefrom
Authors: Sasaki Tadashi , Yoshioka Toshiyuki , Suzuki Yasuyuki 
Published: July 2006

Abstract
ω-Chloroisonitrosoacetophenone was treated with ethylenic and acetylenic dipolarophiles to afford 3-benzoylisoxazolinines and -isoxazoles, respectively. With m-nitrobenzaldoxime or m-nitrobenzonitrile, it yielded 3-benzoyl-5-(m-nitrophenyl)-1,2,4-oxadiazole. The phenylhydrazones of the 3-benzoylisoxazole and -oxodiazole thus produced were converted to the corresponding 1,2,3-triazoles thermally or by the treatment with a base. The photoinduced rearrangement of 3-benzoyl-5-phenylisoxazole afforded 2-benzoyl-5-phenyloxazole. Treatment of ω-chloroisonitrosoacetophenone with aziridine afforded a new type of aziridine oximes, which was converted to 2-benzoyloxazoline.
Solvolysis of Organic Phosphates. III 3-Pyridyl and 8-Quinolyl Phosphates in Spontaneous Reaction
Authors: Murakami Yukito , Sunamoto Junzo 
Published: July 2006

Abstract
The spontaneous hydrolysis of 3-pyridyl and 8-quinolyl phosphates was investigated at 60, 70, and 80°C over the −log[H+] range from 1 to 7 in aqueous media with an ionic strength of 0.10. The reactions followed apparent first-order kinetics with respect to the unreacted phosphate species, and the maximum rate was observed around −log[H+]=2.5. Reactive species of each phosphate in hydrolysis were the neutral zwitterion and the monoanion, the former being found to be more labile. In a moderately acidic region (−log[H+]&lt;2.0), an apparent enhancement of the reaction rate was detected for both phosphates, which was attributed to the acid catalysis acting on the zwitterion species. The activation enthalpy for hydrolysis of the zwitterion and the monoanion falls near 30 kcal mol−1. This is consistent with the reaction mechanism expected for hydrolysis of ordinary monoalkyl or monoaryl phosphate, in which the P–O bond cleavage takes place. The activation entropy data also provide an evidence for the unimolecular nature of the transition state. The kinetic solvent isotope effect kH2o/kD2o for the hydrolysis of both phosphates falls near unity. The isotope effect in this magnitude is consistent with the intramolecular proton-transfer mechanism. The results are, therefore, consistent with a mechanism for the hydrolysis of the zwitterion species of 8-quinolyl phosphate in which the quinolinium group donates a proton intramolecularly to the leaving ester oxygen atom in the transition state.
A Novel Cyclodimerization of Butadiene. A Synthetic Route to 2-Methylenevinylcyclopentane
Authors: Kiji Jitsuo , Masui Kazuo , Furukawa Junji 
Published: July 2006

Abstract
In the presence of a controlled amount of alcohol, the dimerization of butadiene to produce 2-methylenevinylcyclopentane has been shown to occur by means of several nickel catalysts. The most effective nickel catalysts are: (1) (Bu3P)2NiX2 (X=Cl and Br) and organolithium, (2) (o-tolyl)NiX(PEt3)2 (X=Cl, Br, and I), and (3) π-allylnickel bromide and tri-n-butylphosphine. A detailed study of the role of alcohol during the reaction by the arylnickels is presented. In the presence of butadiene, the aryl-nickel bond of (o-tolyl)NiX(PEt3)2 is reductively cleaved by methanol to give toluene, and then the dimerization of butadiene occurs. With CH3OD as the reducing reagent, toluene is not deuterated, but with CD3OD the aromatic ligand is deuterated on the carbon originally bonded to nickel to give monodeuterotoluene.
Phosphorylation of Alcohols and Phosphates by Oxidation-Reduction Condensation
Authors: Mukaiyama Teruaki , Hashimoto Mitsunori 
Published: July 2006

Abstract
Phosphorylation of alcohols and phosphates forming mixed esters of phosphoric acid and pyrophosphate by the oxidation-reduction condensation with triphenylphosphine and 2,2′-dipyridyl disulfide has been investigated. n-Butyl p-nitrophenyl phosphate was obtained in 80% yield when p-nitrophenyl dihydrogen phosphate was treated with one equiv. each of triphenylphosphine and 2,2′-dipyridyl disulfide in the presence of three equiv. of anhydrous n-butyl alcohol at room temperature. It was found that P1,P2-bis(p-nitrophenyl)pyrophosphate was obtained in 91% yield when p-nitrophenyl dihydrogen phosphate was treated with 1.5 equiv. each of triphenylphosphine and 2,2′-dipyridyl disulfide.
Structure of Polynucleotide Complex with Non-Complementary Nucleosides. II. Poly I, U + Poly C
Authors: Akutsu Hideo , Tsuboi Masamichi 
Published: July 2006

Abstract
Three copolymers of riboinosinic acid and ribouridylic acid (poly I,U) with uridylic acid contents, 20, 32, and 44% were prepared. The ultraviolet absorption measurements were carried out with aqueous solutions of mixtures of poly I,U and polytribocytidylic acid (poly C) of various mole ratios. It has been shown that a double-helical structure is formed with an I···C type inter-base binding and with the U residue looping out of the helix. The structure was found to break on heating the solution. The process of break down was followed by means of ultraviolet absorption measurements.
Anisotropy of the Indirect Nuclear Spin-Spin Coupling Constants. III. Problems in the Structure Determination of the Molecule Dissolved in a Nematic Solvent
Authors: Nakatsuji Hiroshi , Morishima Isao , Kato Hiroshi , Yonezawa Teijiro 
Published: July 2006

Abstract
Anisotropy of the indirect nuclear spin-spin coupling constant was studied theoretically. All the contributions to the coupling tensors were calculated for various molecules by using the INDO molecular orbitals. As shown in part I of this series, the calculated 13C–H coupling anisotropy of 13CH3F is too small to be compared with the value obtained experimentally by Krugh and Bernheim. Thus we examined the substituent effect on the anisotropy in the 13CH3X series. It is concluded that the experimentally estimated value of the 13C–H coupling anisotropy in 13CH3F as large as 1890 Hz is erroneous and that it contains some other effects which are more important than electronic effect. We believe that the change in molecular geometry from gas state to the solute state in a nematic solvent is the most probable origin for the differences between theories and experiments. For the directly bonded C–X couplings (X is C, N or F), their anisotropies are in the same order of magnitude as their isotropic couplings. For the non-bonded C–X nuclei, they seem negligible in magnitude. For the F–F couplings, their anisotropies are exceptionally large and the orbital term is a very important source of anisotropy. Furthermore, even for the isotropic F–F couplings, the orbital and spin dipolar terms are very important and sometimes make decisive contributions exceeding the Fermi contact term.
The Interpretation of the EPR Spectra of the Amorphous State of Group VIB Hydride Radicals by Means of the Gas-phase Data
Authors: Kotake Yashige , Ono Mitsuo , Kuwata Keiji 
Published: July 2006

Abstract
A new procedure for the interpretation of the amorphous EPR spectra of the group VIB hydride radicals, i.e., OH, SH, SeH, and TeH, is proposed. The point of this method is to combine the observed hyperfme structure of these radicals in the gas phase and the calculation of the anisotropic hyperfine coupling constant. For this purpose, the Slater orbital and analytical Hartree-Fock orbitals were examined as unpaired electron orbitals by the comparative calculation of the hfs constants. The accuracy of this method was evaluated successfully by applying it to the OH radical. Moreover, in the case of the SH radical the newly-observed spectra in the amorphous state could be assigned to the SH radical.
Measurements of Total Cross Sections for the Scattering of Potassium Atoms by Rare Gases
Authors: Kusunoki Isao 
Published: July 2006

Abstract
Total cross sections for the scattering of potassium by He, Ne, Ar, Kr, and Xe have been measured in the thermal energy range. The velocity of potassium beam is selected by a velocity selector of a slotted disk type. To obtain accurate total cross sections, the pumping effect of a McLeod gauge for the pressure measurements, the fringe effect of the scattering chamber, corrections for angular resolution and for thermal motion of the target gases are taken into consideration. A new type of scattering chamber with a variable length is used to eliminate the error of the effective scattering path length. Velocity dependence of total cross sections has been obtained and glory undulations are observed for potassium-xenon systems. For argon, krypton, and xenon the van der Waals constants are calculated from the absolute total cross sections. The values of CK–Ar, CK–Kr, and CK–Xe are 237, 354, and 535×1060 erg·cm6, respectively, and are in good agreement with the theoretical ones of Dalgarno and Davison. For neon the velocity dependence of the total cross section can not be explained by the van der Waals potential, −C⁄rs, where s=6. For helium the correction factors for thermal motion of the scattering gas are large and the value of s for attractive potential can not be determined unambiguously.
Ferrocene Polymers Obtained by the Polycondensation of Ferrocene with Dicarboxylic Acid Chlorides
Authors: Asahara Teruzo , Sen\={o} Manabu , Mitsuhashi Keiryo , Ichikawa Yohsuke 
Published: July 2006

Abstract
The polycondensation reactions of ferrocene with terephthaloyl and adipoyl chloride were investigated in the presence of AlCl3, ZnCl2, or FeCl3 as the catalyst and in dichloromethane, n-hexane, carbon tetrachloride, or dioxane as the solvent. With terephthaloyl chloride, the highest polymer yield was obtained when AlCl3 in n-hexane was used, and the product was mainly of a polyketone structure. The polycondensation with adipoyl chloride afforded the most satisfactory result when ferrocene was treated in liquid adipoyl chloride with neither catalyst nor solvent, and a product with the expected structure was obtained. The average molecular weights of the products are in the range of 3000–7000. Polymers obtained by polycondensation with terephthaloyl and succinyl chloride are paramagnetic and show the temperature dependence characteristic of semi-conductivity.