bluuebunny/crossref_metadata_2025_split huggingface dataset:
Layered Compounds. LXIV. Syntheses and Charge Transfer Spectra of Multilayered Paracyclophanequinones
Authors: Machida Hideki , Tatemitsu Hitoshi , Otsubo Tetsuo , Sakata Yoshiteru , Misumi Soichi 
Published: July 2006

Abstract
Three isomeric triple-layered and two isomeric quadruple-layered charge transfer cyclophanes containing benzoquinone and dimethoxybenzene moieties have been synthesized together with two triple-layered and two quadruple-layered paracyclophanequinones. The structures of the isomers were determined by 1H- and 13C-NMR spectra and/or alternative syntheses. By comparing the CT bands of a series of dimethoxycyclophanequinones with those of the corresponding cyclophanequinones, it is concluded that the CT stabilization of multilayered dimethoxyquinones should be attributed mainly to the π-basicity of the durene ring which faces the acceptor quinone ring and partly to the decreasing π-basicity of dimethoxybenzene ring as the layer number increases. No orientational dependence of quinone and dimethoxybenzene moieties on GT transition was observed in the multilayered series.
Structure of α Form of l-Glutamic Acid. α-β Transition
Authors: Hirayama Noriaki , Shirahata Kunikatsu , Ohashi Yuji , Sasada Yoshio 
Published: July 2006

Abstract
An X-ray analysis of the α form of l-glutamic acid, C5H9NO4, has been carried out. The space group is P212121 with a=7.068(1), b=10.277(1), c=8.755(1) Å and Z=4. The structure was solved by the direct method, and least-squares refinement using 855 reflexions led to the final R value of 0.034. The molecule is in a zwitter ion form, and there is a strong OH···O intermolecular hydrogen bond with the O···O distance of 2.578(2) Å. The conformation of l-glutamic acid in the α form is quite different from that in the β form. The occurence frequency in various crystal structures containing glutamic acid residues shows that the conformation in the β crystal is more stable and favourable than that in the α crystal. The transition of the α form to the β form of l-glutamic acid in the mother liquor and the conditions for obtaining the α crystals are discussed based on the crystal and molecular structures of the two polymorphs.
A Study of the Ligand Exchange of Bromo(o-tolyl)bis(triphenylphosphine)nickel(II) with Amine by Means of 31P-and 13C-NMR Spectroscopy
Authors: Nakamura Yoshiyuki , Maruya Ken-ichi , Mizoroki Tsutomu 
Published: July 2006

Abstract
The amine substitution of bromo(o-tolyl)bis(triphenylphosphine)nickel(II) was investigated by the use of 31P- and 13C-NMR. The triphenylphosphine ligands are readily replaced by sterically less crowded amines, such as primary amines, secondary amines, pyridine, and γ-picoline, at room temperature in chlorobenzene, while no replacement at all takes place with tertiary amines. The equilibrium constants with γ-picoline, pyridine, or dibutylamine, as defined by Eq. 2, show that the entropy change contributes predominantly to the constant. The substitution with pyrrolidine, as monitored by means of 13C-NMR, indicates that the amine coordinates to the nickel(II) atom.
Raman Scattering Study on Coordination Structures of Cu(II)–l-Histidine(1: 2) in Aqueous Solutions
Authors: Itabashi Masao , Itoh Koichi 
Published: July 2006

Abstract
The pH and pD dependences of the Raman spectra of Cu(II)–l-histidine (1:2) and Cu(II)–l-histidine-d3−5 (1:2) were analyzed based on the pH titration data. Several ring vibrations of the imidazolyl group with cationic, neutral and anionic forms, the out-of-plane bending vibration of the bound carboxylate, and the Cu(II)–N stretching vibrations of the bound amino groups are used to study the chelation structures of the species taken by the solutions. From the results it was concluded that MHA2+, the major species below pH 3, assumes a glycine-like chelation structure with an unbound imidazolium cation. The results also indicate that the species MHA2+, which is prominent in the pH region 4.0–4.5, takes a mixed-type structure, in which one histidine molecule coordinates to Cu(II) as a terdentate ligand and another binds as a substituted glycine. MA2, the major species around pH 7, is determined to have the chelation structure in which two nitrogen atoms of the amino groups and two nitrogen atoms of the imidazole rings are bound to the Cu(II) ion in the square-planar trans position and at least one carboxyl group in the axial position.
Restricted SCF and MC-SCF Study of the Σ and II States of the Formyloxyl and Formylaminyl Radicals
Authors: Kikuchi Osamu 
Published: July 2006

Abstract
Open-shell restricted SCF and MC-SCF methods with the semi-empirical MINDO/3 approximation have been applied to the Σ and II states of the formyloxyl and formylaminyl radicals. In the MC-SCF formalism, the π→π* singly- and doubly-excited configurations are included. The optimized molecular structures and spin distributions predicted by the SCF and MC-SCF methods are compared. For the II state of formyloxyl, the restricted SCF method gives a distorted Cs structure as the most stable II structure, while the MC-SCF gives a symmetric C2V structure. The use of the MC wavefunctions is recommended for the evaluation of the molecular and electronic structures of these radicals, in which a doublet instability of the restricted SCF solution is expected to occur.
Hydrogenation Activity and Selectivity of Cobalt Boride and Cobalt Nickel Binary Boride Catalysts
Authors: Nitta Yuriko , Imanaka Toshinobu , Teranishi Shiichiro 
Published: July 2006

Abstract
Co–B catalyst has higher selectivity than Ni–B catalyst for the formation of α,β-unsaturated alcohols from α,β-unsaturated aldehydes and lower selectivity for the formation of olefins from acetylenes. The differences between the two catalysts can be ascribed to the differences in the adsorption strength of reactants on Co and Ni metals. The hydrogenation activities of the Co–Ni–B catalysts vary through a maximum, but the selectivities vary monotonously with nickel content. These features are explained in terms of the surface composition measured by XPS and of the surface area of the catalysts. The enrichment of nickel on the surface and the increase of the surface area are observed for the Co–Ni–B catalysts. Co–B catalysts modified by a small amount of metal salts (Fe, Cr, Cu, etc.) are more effective for the selective hydrogenation of α,β-unsaturated aldehydes than co-precipitated binary boride catalysts.
Catalytic Properties of Iron Oxides. II. Isotopic Exchange of Oxygen, Oxidation of Carbon Monoxide, and Reduction-Oxidation Mechanism
Authors: Sakata Kanji , Ueda Fumio , Misono Makoto , Yoneda Yukio 
Published: July 2006

Abstract
The reactivity and mobility of the lattice oxygen of iron oxide, in particular γ-Fe2O3, has been investigated by 18O-exchange with CO2 and CO oxidation by 18O2. The low mobility of the lattice oxygen is in agreement with the reduction-oxidation mechanism of γ-Fe2O3 bulk, which proceeds by Fe ion migration without diffusion of the lattice oxygen. The rapid diffusion of the Fe ion makes the redox cycles of γ-Fe2O3 easy and explains, together with the cation deficient structure, the high reactivity and selectivity of lattice oxygen. Thus, γ-Fe2O3may be regarded as a new prototype of selective catalyst for allylic oxidation.
Studies on the Polymerization of Acrolein Oxime. XIV. The Structure of 2,4,7-Trimethylperhydroisoxazolo[2,3-a]pyridine-2,7-dicarbaldehyde Dioxime
Authors: Ota Tadatoshi , Masuda Seizo , Kido Masaru 
Published: July 2006

Abstract
The thermal oligomerization of methacrylaldehyde oxime leads preferentially to two 2,4,7-trimethylperhydroisoxazolo[2,3-a]pyridine-2,7-dicarbaldehyde dioximes, which are comformationally isomeric with each other. The crystal structure of the α-form has been determined by means of X-ray diffraction. It is monoclinic, with the space group P21/a. The cell dimensions are a=7.858(3), b=13.186(6), c=17.259(6) Å, β=130.38(3)°, and Z=4. The molecules are linked by OH···O and OH···N intermolecular hydrogen bonds, with the O···O and O···N distances of 2.794(6) and 2.760(5) Å respectively. Since attempts of the crystallization of the β-form have been unsuccessful, the determination of its chemical structure was attempted by means of 13C-NMR spectroscopy and gas chromatography-mass spectrometry. The β-form is, at any rate, different from the α-form.
Restricted Rotation Involving the Tetrahedral Carbon. XXXIV. Stable Rotamers of 9-Arylfluorenes Carrying Oxygen-substituents in the Ortho Position of the Aryl Group
Authors: Nakamura Mikio , Oki Michinori 
Published: July 2006

Abstract
9-(2-Hydroxy-1-naphthyl)fluorene, 9-(2-hydroxy-4,6-dimethylphenyl)fluorene, and their methyl ethers have been prepared. They give stable rotamers, sp and ap, at room temperature, ap forms of the hydroxylic compounds are favored over the sp and contrary is true for the methyl ethers. These results are attributed to the stabilization of the ap form of the hydroxylic compounds due to intramolecular OH···π interaction. Barriers to rotation are ca. 105 kJ mol−1.
Synthetic Studies of Rifamycins. II. Syntheses of Methyl 2,4,6,7-Tetradeoxy-4-C-methyl-3-O-methyl-α-l-arabino-heptopyranosid-6-ulose and Its Derivatives Utilizable in the Construction of the Rifamycin Ansa Chain Portion
Authors: Nakata Masaya , Ikeyama Yutaka , Takao Hideaki , Kinoshita Mitsuhiro 
Published: July 2006

Abstract
3,6-Dideoxy-3-C-methyl-2-O-methyl-d-galactopyranose(12) was prepared in 10 steps from methyl 4,6-O-benzylidene-3-deoxy-3-C-methyl-α-d-altropyranoside. 12 was converted into 4,5-di-O-acetyl-3,6-dideoxy-3-C-methyl-2-O-methyl-d-galactose, which was then condenced in ether with (methoxymethylene)triphenylphosphorane (generated from the phosphonium salt with the dimethylsulfinylmethanide anion in ether) to produce 5,6-di-O-acetyl-2,4,7-trideoxy-4-C-methyl-1,3-di-O-methyl-d-galacto-1-enoheptitol (16). The treatment of 16 with NBS in methanol, followed by the debromination of the resulting 2-bromo aldehyde dimethyl acetal with tributylstannane, deacetylation, and mild methanolysis afforded methyl 2,4,7-trideoxy-4-C-methyl-3-O-methyl-β-d-galacto-heptopyranoside(19), which then provided the title compound 20 upon Jones oxidation. The potential intermediates, the 1-lithio-1-(methyl 2,4-dideoxy-4-C-methyl-3-O-methyl-α-l-arabino-pentopyranos-5-yl)ethene and (E)-2-(methyl 2,4-dideoxy-4-C-methyl-3-O-methyl-α-l-arabino-pentopyranos-5-yl)propenylcopper intermediates, were prepared from 20 via the corresponding alkenyl iodide and (methyl 2,4-dideoxy-4-C-methyl-3-O-methyl-α-l-arabino-pentopyranos-5-yl)ethyne and were demonstrated to condense with benzaldehyde and ethylene oxide respectively.
Catalysis of the Hydrolysis of p-Nitrophenyl 1-Adamantaneacetate by Cyclodextrins
Authors: Komiyama Makoto , Inoue Shohei 
Published: July 2006

Abstract
The cleavage of p-nitrophenyl 1-adamantaneacetate was accelerated by β- and γ-cyclodextrins, which was in contrast with their deceleration of the cleavage of a sterically analogous substrate, p-nitrophenyl 1-adamantanecarboxylate. The presence and absence of a methylene group in these substrates absolutely governed the directions of the rate effects of the cyclodextrins. The specificity, explicitly showing that cyclodextrins are quite good models of enzymes, was attributed to the difference of the structures of the inclusion complexes of cyclodextrins with these substrates.
Formation of Chiral Aggregates of Acylamino Acids in Solutions
Authors: Sakamoto Kazutami , Hatano Masahiro 
Published: July 2006

Abstract
An alcoholic solution of optically active acylamino acid (AAA) was found to show a circular dichroism (CD) band at 212 nm. The CD band should be inherent to the solution system, since AAA and alcohol per se have no absorption band at this wavelength. The CD band intensity decreased on addition of urea and rise in temperature. This is attributed to the formation of chiral aggregate through hydrogen bonds among AAA molecules. Hydrophobic interaction seems to be of minor importance for the formation of the chiral aggregate in alcoholic solution, since the variation of the chain length in the acyl group or addition of myristic acid did not affect the magnitude of profile of the CD band. In aqueous solutions, salts of optically active AAA formed micelles with hydrophobic interactions among the molecules, and only in the case of optically active monosodium salt of N-acylglutamic acid (AGS) showed a CD band at 220 nm resulting from the formation of chiral hydrogen bonds at concentrations above the critical micelle concentration (CMC). This type of chiral aggregation may be caused by the existence of free carboxyl group in the optically active AGS molecule.
The Crystal and Molecular Structure of the Copper(I) Chloride Complex Containing p-Benzoquinone as a Ligand
Authors: Uechi Tetsuo , Yamaguchi Hiroko , Ueda Ikuhiko , Yasukouchi Kazuo 
Published: July 2006

Abstract
The crystal and molecular structure of the red compound, [(NH4)Cu3Cl4(C6H4O2)1.5·H2O], has been determined from 2115 X-ray diffraction data collected on an automated four-circle diffractometer. The crystals are monoclinic, with space group P21/c, and with four formula units in a unit cell of dimensions; a=7.308(5), b=11.593(7), c=18.359(9) Å, and β=90.16(3)°. The structure was solved by direct methods, and block-diagonal leastsquares refinements led to a final discrepancy index, R, of 0.035. The crystal structure is characterized by polymeric, beehive-like layers composed of Cu3Cl4− anions, and centro- and pseudocentrosymmetric p-benzoquinone molecules. Each of the p-benzoquinone molecules acts as a bridging ligand to the two trans Cu3Cl4− anions, with the Cu–C closest distances falling in the range from 2.047(5) to 2.086(5) Å. The NH4+ cations and the water molecules are accommodated by a roughly coplanar arrangement within the tunnel-like holes of the beehives, and the NH4+ cations are joined to the layers by intra- and interlayer hydrogen bonds of the N–H···O type. The Cu3Cl4− has a distorted cubane-type structure with one corner missing, and each Cu atom has a distorted tetrahedral coordination.
The Kinetics of the Polymerization of Silicic Acid
Authors: Shimada Kanichi , Tarutani Toshikazu 
Published: July 2006

Abstract
The process of the polymerization of silicic acid can be divided into three steps: (1) a reaction between monosilicic acids, (2) a reaction between monosilicic and polysilicic acids, and (3) a reaction between polysilicic acids. The rates of the reactions between monomer-monomer, monomer-polymer and polymer-polymer are most rapid at pH values around 9.3, 8.5, and 6.8 respectively. It is concluded that, above about pH 4, the polymerization due to Reactions 1, 2, and 3 proceeds mainly by a reaction between ionized and un-ionized silanol groups.
The Hydrothermal Preparation and Characterization of Platinum Metal Complexes with Ethylenediaminetetraacetic Acid and Propylenediaminetetraacetic Acid
Authors: Saito Masami , Uehiro Takashi , Yoshino Yukichi 
Published: July 2006

Abstract
A new method for hydrothermal syntheses of osmium(III), ruthenium(III), iridium(III), and rhodium(III) complexes with ethylenediaminetetraacetic acid (EDTA) and propylenediaminetetraacetic acid (PDTA) has been developed. More than ten new complexes have been obtained in good yields and characterized by measuring their magnetic susceptibilities, infrared and electronic spectra, and acid-base properties. The stereochemical behavior of the iridium(III) and rhodium(III) complexes has also been described.
Studies on Nucleosides and Nucleotides. VIII. Preparation and Reactions of Triphenylphosphoranediylnucleosides
Authors: Kimura Junji , Yagi Kentaro , Suzuki Hideyuki , Mitsunobu Oyo 
Published: July 2006

Abstract
The reaction of uridine, N4-benzoylcytidine, guanosine, and N6-p-toluoyladenosine with diethyl azodicarboxylate and triphenylphosphine resulted in the formation of the corresponding 2′,3′-O-(triphenylphosphoranediyl)-cyclonucleosides. On the other hand, adenosine afforded, under similar conditions, 3′,5′-O-(triphenylphosphoranediyl)adenosine (19). The difference can be explained in terms of the acidity of base moieties of the nucleosides. The reaction of 2′,3′-O-(triphenylphosphoranediyl)-O2,5′-cyclouridine, N4-benzoyl-2′,3′-O-(triphenylphosphoranediyl)-O2,5′-cyclocytidine, 2′,3′-O-(triphenylphosphoranediyl)-N3,5′-cycloguanosine, or N6-p-toluoyl-2′,3′-O-(triphenylphosphoranediyl)-N3,5′-cycloadenosine with nucleophiles and with electrophiles addorded the corresponding nucleoside derivatives with free 2′- and 3′-hydroxyl groups. Thus the 2′,3′-O-triphenylphosphoranediyl group serves as a protecting group which is readily removed during work-up of the reaction products. 19 reacted with phenyl isocyanate to give 5′-O-phenylcarbamoyladenosine and N6,5′-O-bis(phenylcarbamoyl)adenosine. The reaction of 19 with diphenylketene also afforded acyladenosines with free 2′- and 3′-hydroxyl groups. These results suggested that 3′,5′-O-triphenyl phosphoranediyl group activates the 5′-carbon atom of adenosine.
The Ultraviolet Spectrophotometric Determination of Iron with 2-Thenoyltrifluoroacetone in an Aqueous Solution Containing α-Hydro-ω)-dodecyloxynona(oxyethylene)
Authors: Taketatsu Tomitsugu , Sato Atsuko 
Published: July 2006

Abstract
2-Thenoyltrifluoroacetone is used as a spectrophotometric reagent for the iron(III) ion (0–1.5 (μg ml−1) in a 0.5% α-hydro-ω-dodecyloxynona(oxyethylene) aqueous solution at pH 3.2–3.8. The molar absorptivities of the iron(III) complex at 338, 388, and 500 nm are 4.75×104, 2.30×104, and 4.85×103 1 mol−1 cm−1 respectively. Many diverse ions do not interfere.
Binuclear Metal Complexes. XXXV. Synthesis and Magnetism of Binuclear Copper(II) Complexes with 3-[2-(Dialkylamino)ethylthio]-1-propanols
Authors: Mikuriya Masahiro , Okawa Hisashi , Kida Sigeo 
Published: July 2006

Abstract
Binuclear copper(II) complexes with 3-[2-(dialkylamino)ethylthio]-1-propanols, Cu[R2N(CH2)2S(CH2)3O]X (R=CH3, C2H5; X=NO3−, ClO4−), were prepared and their magnetic properties were investigated in the temperature range 80–300K. The magnetisms were interpreted in terms of the Bleaney-Bowers equation with exchange integral −J=450–495 cm−1, which is much larger than the values (−J=≈250 cm−1) for Cu[R2N(CH2)2NH(CH2)3O]X.
Metal Complexes Coordinating Pyridine Derivatives. I. Preparation and Circular Dichroism Spectra of cis-α Isomers of [(S)-N,N′-Bis(2-pyridylmethyl)propylenediamine]dihalogenochromium(III) and -cobalt(III) Complexes
Authors: Yamamoto Yukihiro , Shimura Yoichi 
Published: July 2006

Abstract
Several chromium(III) and cobalt(III) complexes with (S)-N,N′-bis(2-pyridylmethyl)propylenediamine (S-picpn) were prepared and their structures assigned. The [CoCl2(S-picpn)]+ complex was reassigned to have cis-α configuration. The Δ and Λ diastereomers of [CrX2(S-picpn)]+ of cis-α. configuration were obtained (X=Cl− and Br−) and their absorption and circular dichroism spectra were discussed.
Benzo-15-crown-5–Aluminium Chloride Complexes of Unusual Stability
Authors: Wada Fumio , Matsuda Tsutomu 
Published: July 2006

Abstract
Among twelve crown ethers of 12, 15, 18, and 21 rings only benzo-15-crown-5 and those with an electron-releasing substituent formed the complexes with aluminium chloride which were stable in methanol.
Solvent Effect on the Adsorption of 1-Octadecanol at Oil/Water Interface
Authors: Ikenaga Takayuki , Matubayasi Norihiro , Aratono Makoto , Motomura Kinsi , Matuura Ryohei 
Published: July 2006

Abstract
In order to study the effect of solvent on the adsorption at interfaces, interfacial tension was measured as a function of temperature and compositon for the systems of water and solutions of 1-octadecanol in cyclohexane, cyclohexene, mesitylene, toluene, and benzene. The interfacial density of 1-octadecanol and the entropy and energy of interface formation were calculated thermodynamically. It was found that cyclohexane causes a significant adsorption of 1-octadecanol and marked decreases in the entropy and energy changes, giving rise to phase transition from expanded to condensed film, while benzene, toluene, and mesitylene cause only a slight adsorption and small decrease in thermodynamic quantities. Cyclohexene was found to give rise to an intermediate adsorptive behavior of 1-octadecanol. The results were interpreted in terms of the mutual solubility between water and solvents and that of 1-octadecanol in the solvents.
Effect of Pressure on Proton Jumps in Methanol at 25 °C
Authors: Nakahara Masaru , Kumo-oka Yoshio , Osugi Jiro 
Published: July 2006

Abstract
Conductivities of HCl and KCl in methanol containing traces (0.12 to 0.40 mol%) of water have been measured in the concentration range of ≈0.4 to ≈5 mmol dm−3 at 25 °C up to 2000 kg cm−2. The limiting equivalent conductance (Λ°) for HCl and KCl decreased with increasing pressure. The excess proton conductance due to the proton-jump mechanism has been measured by Λ°(HCl)−Λ°(KCl) and found to increase with increasing pressure in nearly and absolutely pure methanol. The acceleration of proton jumps by pressure indicates that the rotation of methanol molecules about the longer molecular axis becomes faster at higher pressure. This anomaly is attributed to distortion with pressure of hydrogen bonds in methanol and to an increase in the repulsive field exerted by the proton on the molecule to rotate.
A Conductance Study of Alkali Metal Ion-15-Crown-5, 18-Crown-6, and Dibenzo-24-crown-8 Complexes in Propylene Carbonate
Authors: Takeda Yasuyuki , Yano Hisao , Ishibashi Masayuki , Isozumi Hiroshi 
Published: July 2006

Abstract
The formation constants, KML+, for 1:1 complexes of 15-crown-5 (15C5), 18-crown-6 (18C6), and dibenzo-24-crown-8 (DB24G8) with alkali metal ions and the limiting ionic molar conductivities, λ°, of the complexed cations in propylene carbonate have been determined at 25 °C conductometrically. The KML+ value series about the same alkali metal ion among the crown ethers are given in the order 18C6&gt;&gt;DB24C8&gt;15C5. The KML+ sequences of the alkali metal ions with 15C5, 18C6, and DB24C8 are Li+&gt;Na+&gt;K+&gt;Rb+&gt;Cs+, K+&gt;Na+&gt;Rb+&gt;&gt;Cs+, and Na+&gt;K+&gt;Rb+≥Cs+, respectively. The indication is that the ability of the alkali metal ions to form complexes with the three crown ethers is not always affected primarily by the relative sizes of the alkali metal ions and the crown ether cavity. In each case of 18C6 and DB24C8 the λ° values of the alkali metal ions are nearly equal, while in the case of 15C5 there are considerably differences, suggesting that in the former case the charge of the alkali metal ion trapped in the crown ether cavity is effectively shielded. This is not true in the latter case.
The Crystal Structures of the α and β Forms of Dl-Methionine
Authors: Taniguchi Tomohiko , Takaki Yoshito , Sakurai Kiichi 
Published: July 2006

Abstract
The crystal structures of the α and β forms of Dl-methionine have been refined by block-diagonal least-squares calculations using three-dimensional X-ray data to R=0.118 and 0.088 respectively. The structures of both the forms are essentially the same as those previously reported by Mathieson (Acta Crystallogr., 5, 332 (1952)).
Preparation and Solid-phase Thermal Reactions of Hexaamminechromium(III) Amino Polycarboxylates under Quasi-isothermal and -isobaric Conditions
Authors: Tsuchiya Ryokichi , Uehara Akira , Kobayashi Kazuhiko 
Published: July 2006

Abstract
The following hexaamminechromium(III) amino polycarboxylates were prepared: [Cr(NH3)6]Naedta·3H2O, [Cr(NH3)6]Napdta·6H2O, [Cr(NH3)6]HK3Cl(nta)2·2H2O and [Cr(NH3)6]KCl(nta)·2H2O, where edta, pdta and nta denote ethylenediaminetetraacetate, propylenediaminetetraacetate and nitrilotriacetate ions, respectively. Their thermal reactions in the solid-phase were examined by Q-derivatography (quasi-closed system; quasi-isothermal and -isobaric conditions) and D-derivatography (open system; dynamic conditions). The reactions in open system were too complicated to yield uniform intermediates. On the other hand, each reaction step in the quasi-closed system was definite and reproducible, the products obtained in each reaction step being remarkably pure.