bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of INDOR Method to a Relatively Slow Exchange System. OH Protons of the 1,3-Dihydroxyacetone Dimer in Dimethyl-d6 Sulfoxide
Authors: Kuroda Yoshihiro
Published: July 2006

The nuclear magnetic multiple-resonance method developed by Forsén and Hoffman for the study of exchange rates has been applied to the two different types of OH protons of the 1,3-dihydroxyacetone dimer in dimethyl-d6 sulfoxide, i.e., OH (α) and CH2OH (β). Here, “decay” and “recovery” curves were obtained using the so-called “INDOR” method, instead of a rapid repetitive scan method. Since the INDOR method continuously monitors a peak height, decay and recovery curves as fast as 1 s can be drawn by storing them in a computer after a single scan. The concentration dependence was examined as a two-site exchange system by neglecting the small amount of water (γ) contained in the dimethyl sulfoxide solvent. Both the lifetime, τ, and the longitudinal relaxation time, T1 obtained from this assumption correlate well with the concentration variation of the 1,3-dihydroxyacetone dimer. The difference in the types of OH protons on the concentration dependence is clearly seen for the latter parameter, T1. From the triple-resonance experiments including γ, it was found that the β proton is more “labile” than the α.
Pentamethylnitrosobenzene as a Spin-trapping Agent
Authors: Doba Takahisa , Ichikawa Tsuneki , Yoshida Hiroshi
Published: July 2006

Pentamethylnitrosobenzene synthesized readily from pentamethylbenzene was studied for utilization in a spin-trapping technique. In a benzene solution it forms a dimer with a dissociation constant of 105.26exp(−50⁄RT) in units of kJ/mol. It traps the t-butyl radical with the trapping rate constant of 1.4×108 mol−1 dm3 s−1 at 299 K. It is thus an efficient spin-trapping agent, even though only a fraction of it is reactive with the short-lived free radicals because the equilibrium lies more on the side of the dimeric form. Electron spin resonance parameters were determined for the spin-adduct radicals derived from alkyl, alkoxyl, and phenyl radicals with this trapping agent. These free radicals were found to attach exclusively to the nitrogen atom of the nitroso compound.
Crystal Structure and Electrical Conductivity of Tetrathiafulvalene Thiocyanate (TTF)(SCN)0.57
Authors: Kobayashi Hayao , Kobayashi Keiji
Published: July 2006

The organic conductor, (TTF) (SCN)0.57, is a quasi-one-dimensional non-stoichiometric compound, which crystallizes in a tetragonal system having a P42/mnm space group. The lattice constants are a=11.154 (3) and c=3.607 (2) Å. TTF molecules form segregate eclipsed stacks with thiocyanate ions occupying the channels between the stacks. The intermolecular distance between adjacent TTF molecules is 3.607 Å. The room-temperature electrical conductivity is 85–310 (Ω cm)−1. A series of resistance jumps are observed in the temperature-dependent resistivity curves.
Kinetic Studies on Double Relaxation of Surfactant Solutions Using a Capillary Wave Method
Authors: Sasaki Minoru , Yasunaga Tatsuya , Satake Shigemi , Ashida Minoru
Published: July 2006

The frequency dependence of the damping coefficient of a capillary wave was measured in decylamine hydrochloride solutions. The observed relaxations were well expressed by the double-relaxation equations. From the concentration dependence of the relaxation parameters obtained, the relaxations at low and high frequencies were attributed to the adsorption-desorption and ion-pair formation reactions on the surface, respectively. Furthermore, the adsorption rate constants are related to the hydrophobic and hydrophilic properties of the surfactants.
Synthetic Photochemistry. VII. The Addition Reaction of Acenaphthenequinone and 1,2-Naphthoquinone to Cycloheptatriene
Authors: Takeshita Hitoshi , Mori Akira , Funakura Mitsuru , Mametsuka Hiroaki
Published: July 2006

The photoaddition reaction of acenaphthenequinone and 1,2-naphthoquinone to cycloheptatriene was investigated. In contrast to acyclic α-diketones, various cycloadducts were formed from both quinones; the former giving the (2+2)π-, and (2+6)π-cycloadducts together with the ene-product, and the latter the (2+6)π-, (4+2)π-, and (4+4)π-cycloadducts.
Kinetic Studies of Spin-trapping Reactions. I. The Trapping of the t-Butyl Radical Generated by the Photodissociation of 2-Methyl-2-nitrosopropane by Several Spin-trapping Agents
Authors: Doba Takahisa , Ichikawa Tsuneki , Yoshida Hiroshi
Published: July 2006

The photochemical reaction of 2-methyl-2-nitrosopropane (a spin-trapping agent) in benzene was studied at 299 K by monitoring the optical absorption intensity of the spin-trapping agent and the ESR signal intensity of the spin-adduct radical (di-t-butyl nitroxide). The observed kinetic feature was interpreted in terms of three elementary processes; the photodissociation of the spin-trapping agent giving a t-butyl radical, the spin trapping of the t-butyl radical by the trapping agent giving the spin adduct radical, and the reaction of the spin-adduct radical with the t-butyl radical giving diamagnetic products. The rate constant of the last process was found to be 10 times as large as that of the spin-trapping process, which was determined to be 3.3×106 mol−1 dm3 s−1 based on the reported rate constant for the scavenging of the t-butyl radical by tributylstannane. The relative spin-trapping rate constants toward the t-butyl radical were also determined to be 0.07, 1.0, 41, 63, and much higher than 50 for 2,4,6-tri-t-butylnitrosobenzene, 2-methyl-2-nitrosopropane, pentamethylnitrosobenzene, nitrosodurene and nitrosobenzene, respectively. C-phenyl-N-t-butylnitrone was found to be much less reactive by a factor of less than 0.003.
Absolute Rate Constants for Hydrogen Abstraction from Some Aromatic Hydrocarbons by p-Chlorophenylthiyl Radical
Authors: Miyashita Tokuji , Iino Masashi , Matsuda Minoru
Published: July 2006

The absolute rate constants for hydrogen abstraction from cumene, p-cymene, and tetralin by p-chlorophenylthiyl radical have been determined by means of flashphotolysis and kinetic absorption spectrophotometry. The results are discussed in comparison with those reported for other types of free radicals.
The Crystal and Molecular Structure of Dichloro [N, N-dimethyl-α-methyl-o-(butylphenylphosphino)benzylamine] palladium(II)
Authors: Takenaka Akio , Sasada Yoshio , Yamamoto Keiji , Tsuji Jiro
Published: July 2006

The crystal structure of dichloro[N, N-dimethyl-α-methyl-o-(butylphenylphosphino)benzylamine]palladium-(II) has been determined from MoKα diffraction data. The space group is P21 with Z=2, a=9.255(2), b=14.372 (3), c=8.584(1) Å, and β=105.99(1)°. The final R became 0.034 by least-squares refinement. The Pd atom has a square planar coordination of N, P, and two Cl atoms, which is considerably distorted by the intramolecular atomic repulsions. The Pd–N distance, 2.134(4) Å, which is longer than those found so far, is accompanied by a short distance 2.285(1) Å of trans Pd–Cl. A plot of Pd–Cl distance versus trans Pd–N distance in several Pd complexes, in which the nitrogen atom is not π-acceptor, shows a linear relationship with the correlation factor of −0.28(4).
Preparation and Spectroscopic Studies of Four Stereoisomers of Tris[(S)-1,3-butanediamine]cobalt(III) Complex
Authors: Kojima Masaaki , Fujita Junnosuke
Published: July 2006

Four stereoisomers, mer-Δ, mer-Λ, fac-Δ, and fac-Λ, of the tris[(S)-1,3-butanediamine]cobalt(III) complex were obtained, and their absorption and circular dichroism spectra were recorded in water in the absence or presence of sulfate ions. The shift of absorption bands and the variation of circular dichroism spectra caused by the addition of sulfate ions seem to be correlated with the conformational instability of six-membered (S)-1,3-butanediamine chelate rings in the complexes.
The Disproportionation Constants of Mercury(I) in Dilute Solutions
Authors: Sanemasa Isao , Hirata Tsutomu
Published: July 2006

The disproportionation constants for the Hg22+\ightleftarrowsHg(aq)+Hg2+ reaction have been measured in dilute mercury (I) perchlorate solutions over the temperature range from 15 to 30 °C. The technique was based on a simple kinetic method which made use of a characteristic property of the elemental mercury in aqueous solutions. The disproportionation constant at 25 °C and μ=0.1 was found to be 1.1±0.1×10−8 M, and the associated thermodynamic parameters were ΔH=13.2±0.2 kcal/mol and ΔS=8.0 e.u. The reliability of the method was discussed with relation to the reported values in the literature.
A Relationship between the Circular Dichroism and the Configuration of Asymmetric Nitrogen in trans(N,EthyIene)-chloro-l-aminocarboxylato-η2-ethyleneplatinum(II)
Authors: Terai Yoshiro , Kido Hiroaki , Saito Kazuo
Published: July 2006

The circular dichroism (CD) peaks of trans(N, ethylene)[PtCl(l-am)(C2H4)] (l-am, l-amino carboxylate) in acetonitrile (AN) at 33000 and 37000 cm−1 are characteristic of those complexes with asymmetric nitrogen. The CD sign depends on the substituents on the asymmetric nitrogen, and the additivity law holds for methyl and benzyl derivatives of l-prolinato, l-hydroxyprolinato, and l-valinato complexes. The quadrant rule is applicable to the contribution of the substituents on the nitrogen. On the preparation of the benzyl-l-valinato complex from Zeise’s salt in a weakly acid medium the nitrogen exhibits a marked stereoselectivity to give R configuration.
The Direct Chlorination of Anthraquinone Oxime. The Regioselective Chlorination of Anthraquinone
Authors: Ito Takehiko , Sadakata Koichi , Kindaichi Yoshiaki , Takami Yasuo
Published: July 2006

The reaction of anthraquinone oxime with chlorine in the presence or absence of a catalyst was investigated. In concentrated sulfuric acid, the direct chlorination of anthraquinone oxime takes place easily at 100 °C. The chlorination occurs selectively in the β-position in the absence of a catalyst and in the α-position in the presence of palladium acetate.
Synthesis and Hydrolysis of 4-Acetoxymethylbenzimidazoles, Effects of Freezing an Internal Rotation on Intramolecular Catalysis by a Benzimidazolyl Group
Authors: Utaka Masanori , Takatsu Masahisa , Takeda Akira
Published: July 2006

As models for acetyl-α-chymotrypsin, 4-acetoxymethylbenzimidazole (2), its 5-methyl derivative 3 and 2,5-dimethyl derivative 4 were synthesized from o-toluidine in moderate yields. Their hydrolytic reactivities were determined in water at 50 °C in comparison with their open-chain analog, 4-(acetoxyethyl)imidazole(1). The rate constant (k1) for intramolecular general base catalysis by the imidazolyl group of 2 was 1.6 times larger than k1 for 1. A corrected relative rate of 4.1 is obtained by correcting the basicity difference and the polar substituent effect. The value of 4.1 is an expected magnitude of the effect of freezing an internal rotation as reported for 4,5-(1-acetoxymethyltetramethylene)imidazole. The 5-methyl group of 3 enhances the k1 value 1.4 times as large as that for 2. The enhancement can be attributed to restriction of the second internal rotation. The hydrolytic reactivity of 4 is discussed.
Substituent Effects on Tautomerism of 4-Pyridinethiones
Authors: Besso Hiromichi , Imafuku Kimiaki , Matsumura Hisashi
Published: July 2006

The tautomeric constants Kt of several 4-pyridinethiones were determined by measurement of pKa values. For 2-substituted 5-methoxy-4-pyridinethiones, the Kt values are correlated to the substituent constants σ, by the equation logKt=4.00+3.99σm−7.33σ0.
Aminosugars. XXVIII. A Facile Synthesis of Benzyl α- and β-Kasugaminides via the Corresponding Abequosides
Authors: Yoshimura Juji , Sato Ken-ichi , Hashimoto Hironobu , Shimizu Kuniaki
Published: July 2006

Synthesis of benzyl α- and β-kasugaminides (benzyl 2,4-diamino-2,3,4,6-tetradeoxy-α- and β-d-arabino-hexopyranosides) was carried out by the simultaneous substitution at 2,4-positions of 2,4-di-O-mesyl-abequosides (3,6-dideoxy-2,4-di-O-mesyl-α- and β-d-xylo-hexopyranosides) with sodium azide followed by hydrogenation. The substitution in N,N-dimethylformamide at higher temperature gave the elimination products (4-azido-2,3-unsaturated derivatives) and the subsequently rearranged products (3,4-unsaturated 2-azido derivatives), but, that in hexamethylphosphoric triamide at lower temperature gave the desired compounds in fairly good yields.
Layered Compounds. XLIV. Transannular π-π Interactions in Tetracyanoethylene Complexes of [m.n]Paracyclophadiynes and the Related Cyclic Acetylenes
Authors: Kaneda Takahiro , Misumi Soichi
Published: July 2006

The electronic spectra of TCNE complexes of acyclic and cyclic diacetylenes and cyclic tetraacetylenes were measured. They show a maximum in the narrow region 423–431 nm regardless of ring strain in the donor molecules and proximity of two diacetylene groups. Crystalline two-to-one TCNE complexes of [m.n]paracyclophadiynes were prepared, the formation of one-to-one TCNE complexes in solution being established by means of the Benesi-Hildebrand plots using various molar ratios of the two components. The electronic spectra of some 1: 1 [m.n]paracyclophadiyne–TCNE complexes were measured. The spectra suggest that the complexes are equilibrium mixtures consisting of three isomeric complexes, i.e., a diacetylene-site complex and two pseudo-conformers of benzene-site complex. The longer wavelength band of [m.n]paracyclophadiyne complexes shows a marked red-shift as compared with the other bands. This is interpreted in terms of transannular π-π interaction between the diacetylene group and the benzene ring fixed closely with each other by shortening of methylene bridges. The contribution of the three isomeric complexes on the red-shift is discussed.
The Reaction of Dammarane Derivatives: Reactions Involving C-20 Carbdnium Ions
Authors: Tori Motoo , Tsuyuki Takahiko , Takahashi Takeyoshi
Published: July 2006

In order to investigate the reaction involving C-20 cation in dammarane derivatives, following reactions were examined: a) (20S)- and (20R)-dammaran-20-ols (13 and 14) with acids, b) dammar-20(22)-en-23-one (15) with hydrochloric acid, c) 20,21- and 20,22-epoxydammaranes (16 and 17) with boron trifluoride etherate, and d) hexanor- and pentanordammaran-20-ols (18 and 19) with phosphoryl chloride and with boron trifluoride etherate, etc., and 20ξ-tosyloxyhexanordammarane (46) with silica gel. Either formation of a double bond in the framework or in the side chain (in the cases of 13, 14, 18, 19, and 46), deconjugation of the double bond (in the case of 15), or formation of a carbonyl group in the side chain (in the cases of 16 and 17) was observed. However, D-homoannulation reaction was not observed in all cases.
A Macrocyclic Enzyme Model System. Deacylation of p-Nitrophenyl Carboxylates as Effected by a [20]Paracyclophane Bearing an Imidazole Group
Authors: Murakami Yukito , Aoyama Yasuhiro , Kida Masaaki , Nakano Akio
Published: July 2006

The kinetic effect of a [20]paracyclophane bearing an imidazole moiety (1) on the deacylation of various p-nitrophenyl carboxylates was investigated in 10.9% (v/v) ethanol-1.0%(v/v) dioxane-water of μ 0.10 (KCl) at 40.0±0.1 °C. The facile reaction of 1 with a hydrophobic ester resulted in the accumulation of the NIm-acyl derivative of 1 along the progress of reaction, and the rate of regeneration of 1 (turnover) was negligibly small under present experimental conditions compared to the corresponding acylation rate. The overall feature for deacylation reactions of p-nitrophenyl carboxylates bearing a hydrophobic acyl moiety in the presence of 1 is consistent with the reaction scheme which involves the reactions of the monomeric and aggregated forms of 1 with substrate esters. The second-order rate constants for reactions of the monomeric species of 1 with relatively hydrophobic esters exceed considerably the corresponding second-order rate constants for imidazole-catalyzed reactions, suggesting the significant hydrophobic interaction between 1 and each hydrophobic ester. The binding constants (K) for complex formation of a micelle (aggregation number, N) with significantly hydrophobic substrates are greater than 105 M−1. The second-order rate constants (kmK⁄N) for reactions of the imidazole group of 1 with the long-chain carboxylates in micellar phase are the largest ever achieved for reactions of synthetic 4-substituted imidazoles with p-nitrophenyl esters.
Reactions of 4-Acyl-2-phenyl-1,3,4-oxadiazoline-5-thiones with Alcohols in the Presence of Metal Ions
Authors: Fukuda Hiroyuki , Endo Takeshi , Okawara Makoto
Published: July 2006

4-Acetyl- and 4-benzoyl-2-phenyl-1,3,4-oxadiazoline-5-thiones reacted with alcohols in the presence of metal ions to give the corresponding esters in good yields.
A Convenient Synthesis of 1-(2′,3′-Dideoxy-β-d-erythro-hex-2′-enopyranosyl)uracil
Authors: Yamazaki Tatsumi , Sugiyama Hiroshi , Matsuda Kazuo , Seto Shuichi
Published: July 2006

2,2′-Anhydro-l-(4′,6′-O-benzylidene-3′-O-methylsulfonyl-β-d-mannopyranosyl)urasil, prepared smoothly from β-d-glucopyranosyluracil in three steps, was converted into the corresponding unsaturated nucleoside in a good yield by the action of sodium iodide. The unsaturated nucleoside was then debenzylidenated with acid to afford the title compound.
Reaction of Bis(trans-1-hexenyl)methylborane with Two Molar Equivalents of Methylcopper(I). Evidence for the Presence of trans-1-Hexenylcopper(I) as an Intermediate
Authors: Yamamoto Yoshinori , Yatagai Hidetaka , Maruyama Kazuhiro , Sonoda Akio , Murahashi Shun-Ichi
Published: July 2006

Bis(trans-1-hexenyl)methylborane, prepared by the reaction of bis(trans-1-hexenyl)chloroborane with methyllithium, was treated with 2 molar equivalents of methylcopper(I) at −78 °C to give (5E,7E)-5,7-dodecadiene quantitatively. The result indicates the presence of trans-1-hexenylcopper(I) intermediate.
Thermal Dissociation of N,N-Dimethylformamide–Tetracyanoethylene and Dimethyl Sulfoxide–Tetracyanoethylene Complexes into Ions
Authors: Kushibiki Nobuo , Yoshida Hiroshi
Published: July 2006

Ionic dissociation of N,N-dimethylformamide (DMF)–tetracyanoethylene (TCNE) and dimethyl sulfoxide (DMSO)–TCNE electron donor-acceptor (EDA) complexes was studied by means of optical absorption and electron spin resonance measurements. Upon dissolving TCNE into DMF or DMSO, essentially all the TCNE became complexed with the electron-donationg solvent; charge-transfer bands with maxima at 310 and 380 nm were found for DMF–TCNE and DMSO–TCNE complexes, respectively. The CT bands were transformed slowly in the dark into the band of TCNE−. This transformation proceeded quantitatively and indicated the dissociation of the EDA complexes into ions. The rate of the ionic dissociation was determined by following a first-order growth of the ESR spectrum of TCNE− at various temperatures: k=108.9exp(79⁄RT) for the DMF–TCNE complex and k=106.3exp(59⁄RT) for the DMSO–TCNE complex, in units of s and kJ/mol. Dissolved oxygen was found not only to react chemically with the complex to form a new stable species, but also to quench physically the ionic dissociation. Upon evacuating the oxygen, the survival fraction of the complex was found to start dissociation again. It is suggested that the ionic dissociation arises from a long-lived precursor state, probably the triplet state of the complex.
The Vibrational Spectra of Tetracyanothiophene
Authors: Nakanishi Jiro , Takenaka Tohru
Published: July 2006

The polarized infrared and far-infrared spectra of the tetracyanothiophene (TCNT) crystals were recorded by means of the normal and oblique incidence of radiation upon the (001) and (20\bar1) sample planes. The Raman spectra of the powdered sample and of a saturated solution in acetonitrile or 1,2-dichloroethane were also obtained. The observed bands were experimentally classified into the symmetry species of the free molecule (the point group C2v) under the assumption of an oriented gas model. Assignments of the observed bands to individual fundamental vibrations were carried out with the aid of the spectral data of the analogous molecules and the normal coordinate analysis of the in-plane vibrations, which was made with a modified Urey-Bradley force field.
Stereochemical Studies of the Electrolytic Reactions of Organic Compounds. II. Electrolytic Reduction of Optically Active 6-Chloro-2,6-dimethyloctane to the Corresponding Alkane
Authors: Nonaka Tsutomu , Ota Tetsuro , Odo Keijiro
Published: July 2006

In order to clarify the mechanism of electroreduction of aliphatic halides, optically active 6-chloro-2,6-dimethyloctane(I), in which an (R)-(−)-enantiomer was present in excess, was electrolyzed at a mercury cathode in various organic solvents. An (R)-(−)-enantiomer was also present in excess in the 2,6-dimethyloctane(II) which was obtained. This result indicates that the reduction of I to II proceeds with an excess of the inversion of the absolute configuration of the starting halide. In this paper, the stereochemistry of a radical intermediate formed at an initial stage in the course of reduction is discussed.
Synthesis of Tuftsin and Its Analogs
Authors: Nozaki Sukekatsu , Hisatsune Kazuhito , Muramatsu Ichiro
Published: July 2006

Tuftsin, a phagocytosis stimulating peptide, was synthesized according to a liquid phase method together with its four analogs, H–Thr–Arg–Pro–Arg–OH (2), H–Thr–Lys–Pro–Lys–OH (3), H–Thr–Arg–Pro–Lys–OH (4), and H–Arg–Pro–Lys–Thr–OH (5).
Carbon-Nitrogen Bond Fission in Ureas and Thioureas. Preparation of Alkyl and Aryl Isothiocyanates Using Carbon Bisulfide and Butyllithinm or a Grignard Reagent
Authors: Sakai Shizuyoshi , Fujinami Tatsuo , Aizawa Toshiyuki
Published: July 2006

The carbon-nitrogen bond in N,N′-diaryl- and dialkyl-thioureas or -ureas was easily cleaved by the metallation of thioureas or ureas using butyllithium, followed by the addition of an excess of carbon disulfide or 1,3-dithiolan-2-thione in tetrahydrofuran under reflux, to afford about two mol of the corresponding isothiocyanates per mol of the thioureas or ureas used. Instead of butyllithium, ethylmagnesium bromide was also effective in such a type of carbon-nitrogen bond fission of the (thio) ureas in refluxing tetrahydrofuran, and in this case the addition of carbon disulfide was not required. To explain these results, a six-centered decomposition of the dilithium salt of N-dithiocarboxy(thio) urea in the reaction using butyllithium was tentatively proposed, while a four-centered mechanism seems applicable to the reaction using ethylmagnesium bromide.
Seven-membered N-Heterocycles. XIII. Rearrangement of 7-Benzyl-4-hydroxy-6,7,8,9-tetrahydro-5H-pyrimido[4,5-d]azepines to 7-Benzyl-4-vinyl-6,7-dihydro-5H-pyrrolo[2,3-d]pyrimidines
Authors: Yamamoto Hiroshi , Kawamoto Heizan , Morosawa Shiro , Yokoo Akira
Published: July 2006

The title pyrimidoazepines when treated with phosphoryl chloride underwent rearrangement to the vinylpyrrolo-pyrimidines via probable intermediates 5-(2-benzylaminoethyl)-4-chloro-6-vinylpyrimidines. Reduction and subsequent dehydrogenation of the products led to the preparation of 4-ethyl-7H-pyrrolo[2,3-d]pyrimidines and their 5,6-dihydro derivatives. The structures are discussed on the basis of pKa values, UV and NMR spectra.
Synthesis of Ripariochromene B and C
Authors: Tsukayama Masao
Published: July 2006

Condensation of 7-hydroxy-2,2-dimethylchroman with benzoyloxyacetonitrile gave 7-hydroxy-6-benzoyl-oxyacetyl-2,2-dimethylchroman (3) which was converted into 7-hydroxy-6-acetoxyacetyl-2,2-dimethylchroman (7) in four steps. Dehydrogenation of 7 with DDQ in dried toluene afforded ripariochromene B (1). Ripariochromene B was also synthesized by oxidative cyclization of 2,4-dihydroxy-5-(3-methyl-2-butenyl)-ω-acetoxy-acetophenone (13) which was prepared from resorcinol and acetoxyacetonitrile in two steps. Ripariochromene C (2) was synthesized from resorcinol by the same method as that described above.
Skeletal Rearrangement of Furanoeremophilane-6β,10β-diol into Farfugin A, Farfugin B, and 6-[(4R)-Chloropentyl]-3,5-dimethylbenzofuran
Authors: Tada Masahiro , Tanahashi Yoshiaki , Moriyama Yoshihiko , Takahashi Takeyoshi
Published: July 2006

Treatment of furanoeremophilane-6β,10β-diol (1; R=H) with phosphoryl chloride in pyridine at 110 °C gave farfugin A (2; yield: 23%), farfugin B (3; y: 34%), and 6-[(4R)-4-chloropentyl]-3,5-dimethylbenzofuran (4; y: 15%). A mechanism of formation of these three compounds (2, 3, and 4) is discussed.
Reaction of 1,1-Diiodoethane with Copper Powder in the Presence of Olefins and/or Alkylbenzenes
Authors: Kawabata Nariyoshi , Yamagishi Nobuyuki , Yamashita Shinzo
Published: July 2006

The treatment of 1,1-diiodoethane with copper powder in the presence of 1-heptene gave a 1.3 : 1 mixture of cis- and trans-1-methyl-2-pentylcyclopropane in 11% yield. The treatment in the presence of cyclohexene gave a 1 : 1.7 mixture of endo- and exo-7-methylbicyclo[4.1.0]heptane in 32% yield, together with 1-ethylcyclohexene in 8% yield, which was shown to be derived mainly from isomerization of the endo-isomer. These reactions were concluded to proceed via organocopper intermediate rather than free methylcarbene. The treatment of 1,1-diiodoethane with copper powder in the presence of alkylbenzene gave a mixture of o- and p-ethyl(alkyl) benzene contrary to the corresponding reaction of methylcarbenoid of zinc which gave cycloheptatriene derivatives.
ESR Studies of Dibenzenesulfenamidyl Radicals
Authors: Miura Yozo , Makita Noboru , Kinoshita Masayoshi
Published: July 2006

Dibenzenesulfenamidyl radicals (2) were generated by the oxidation of dibenzenesulfenamides (1), and their ESR and visible spectra were measured. The ESR spectra were split into a 1 : 1 : 1 triplet by the interaction with the nitrogen nucleus (aN=11.26–11.49 G); in some spectra, each of the triplet was further split by the interaction with the ring protons (ao−H=ap−H=0.48–0.70, am−H=0.18–0.22 G). The g-values lay in the range of 2.0080–2.0083. From the results, it was concluded that the unpaired electron is distributed mainly on the nitrogen and the two sulfur atoms. Kinetic studies of the decay of 2 indicated that 2 decays with second-order kinetics and is not sensitive to the atmospheric oxygen.
Nature of Catalytically Active Sites over Solid Acids. II. Relationships between Acidic Properties of Silica–Alumina and Its Catalytic Activities for Olefin Polymerization
Authors: Take Jun-ichiro , Ikeda Masanori , Yoneda Yukio
Published: July 2006

The influences of the degree of hydration of a silica–alumina surface on its Bronsted or Lewis acid content and on its catalytic activity for cis-2-butene polymerization were investigated at 30 °C as a function of the evacuation temperature. The raise in the evacuation temperature, i.e., the decrease in the degree of hydration, gave rise to an increase in both the Lewis acid content and the catalytic activity but to a decrease in the Bronsted acid concent. A good linear relationship, which could not be extrapolated through the origin, was found between the Lewis acid content and the catalytic activity. Thus, the conclusion is drawn that only strong Lewis acid sites are active in olefin polymerization on silica–alumina at low temperature.
Condensed State Spectra and Phase Transitions of Charge Transfer Autocomplexes
Authors: Freimanis J\={a}nis , M\={a}lmanis Andrejs , Dr\={e}geris J\={a}nis
Published: July 2006

The results of a spectroscopic study of super-cooled melts and crystalline layers of charge-transfer autocomplexes are reported. Samples obtained by sublimation in vacuo or by melting of the complex between transparent plates undergo a “liquid-solid” phase transition. Amorphous films produce absorption bands identical with those obtained from solutions, Whereas crystalline layers are colored depending on intermolecular CT interaction. In some cases transparent crystalline films with pronounced optical anisotropy were obtained.
Kinetic Studies on the Decolorization Reaction of Rosaniline in Aqueous Acidic Medium
Authors: Sinha Sudhir K , Katiyar Sarvagya S
Published: July 2006

The reaction responsible for the decolorization of rosaniline in acid medium has been studied spectrophotometrically. The rate-determining step has been found to be the reaction of the protonated dye cation with water molecule. Kinetic data have been analyzed on the basis of rate equations which were derived considering the complete protolytic scheme involving all the steps of the reaction of rosaniline in acid and alkaline media. The rate constant k1 for the ion-molecule reaction has been found to be independent of the dye concentration and hydrogen ion concentration. The apparent rate constant k at various hydrogen ion concentrations has been utilized for calculating the equilibrium constant for the fast protonation step. Effect of ionic strength in the range 0–0.27 indicates no substantial effect on the rate constant k1. Anomalous solvent effects were obtained suggesting the solvated nature of the reactants. The average energy of activation for the reaction of rosaniline in aqueous medium corresponded to 10.52 kcal. Chemical and kinetic evidence has been presented to prove the participation of water molecule in the rate-determining step.
Emission Spectra of the Vinyl Polymers with Pendant Phenanthryl Groups
Authors: Itaya Akira , Okamoto Ken-ichi , Kusabayashi Shigekazu
Published: July 2006

The emission properties of 9-ethylphenanthrene (EPh), poly(9-vinylphenanthrene) (PVPh), poly(9-phenanthryl methacrylate) (PPhMA), and poly[2-(9-phenanthryl)ethyl vinyl ether] were investigated in solution. These vinyl polymers showed no clear excimer fluorescence in the longer-wavelength region. Both the fluorescence quantum yield and the lifetime of PVPh decreased largely with an increase in temperature at higher temperatures. This suggests that PVPh forms an excimer which has a low fluorescence quantum yield. The fluorescence properties of PPhMA and PPhEVE, in which Ph chromophores are widely spaced on the skeletal chains, indicated little interaction between neighboring Ph chromophores in the singlet state. This results from the nature of Ph, in whith it is difficult to form an excimer. The phosphorescence spectrum and its lifetime of PPhEVE indicated a presence of a weak interaction between neighboring Ph chromophores in the triplet state. PVPh and PPhEVE showed a delayed fluorescence resulting from a T-T annihilation between two migrating triplet excitons.
The Position Dependence of the SCF Screened Potential in Several Pseudo-Jahn-Teller Nonbenzenoid Aromatic Hydrocarbons
Authors: Koyanagi Tsuguo , Yamaguchi Hiroyuki
Published: July 2006

The SCF screened potentials of pentalene, heptalene, and s-indacene were calculated by using the SCF screened potential MO CI method. The characteristics of the screened potential in the nuclear arrangement belonging to the lower molecular symmetry group, C2h, are similar to those of the polyene.
Effect of Pressure on Interfacial Tension between Oil and Water
Authors: Matubayasi Norihiro , Motomura Kinsi , Kaneshina Shoji , Nakamura Makoto , Matuura Ryohei
Published: July 2006

The interfacial tension of hexane, octane, carbon tetrachloride and benzene against water was measured as a function of pressure up to 150 MPa at 303.15 K, using a newly designed apparatus. The interfacial tension showed definite increase with pressure and positive volume change was found on interface formation.
An Improved Gas Circulation Pump
Authors: Yasumoto Isao , Nagai Keizo
Published: July 2006

A gas circulation pump made of glass has been constructed, which works at less than one atmosphere. The pumping speed of the present pump is approximately 4 l/min.
The Crystallization of Pb5Si3O11 from the Glass in the PbO–SiO2 System
Authors: Hasegawa Hiroshi , Shimada Masahiko , Kanamaru Fumikazu , Koizumi Mitsue
Published: July 2006

A new compound, Pb5Si3O11, is prepared by the crystallization of the glass in the PbO–SiO2 system. Pb5Si3O11 has an orthorhombic symmetry, and its lattice parameters are determined to be a0=9.93 Å, b0=8.31 Å, and c0=34.4 Å.
The Crystal Structure of Nitratotriaquo(2,2′-bipyridine)copper(II) Nitrate [Cu(NO3)(H2O)3(bipy)]NO3
Authors: Nakai Hisayoshi , Ooi Shun’ichiro , Kuroya Hisao
Published: July 2006

The crystal structure of the title compound has been determined from three-dimensional X-ray data. The crystal is composed of the nitrate anions and the distorted-octahedral [Cu(NO3)(H2O)3(bipy)]+ cations, where the nitrato-groups act as a monodentate ligand and the three coordinated water molecules occupy a facet of the octahedron.
Carbonylation Reaction of Isoprene Catalyzed by Palladium(II) Acetate and Triphenylphosphine
Authors: Tsuji Jiro , Yasuda Hideyuki
Published: July 2006

The carbonylation reaction of isoprene in alcohol catalyzed by palladium(II) acetate and triphenylphosphine gave 4-methyl-3-pentenoate selectively in a moderate yield. Unlike butadiene, no dimerization-carbonylation of isoprene to give C11 esters took place.
Microdetermination of Furfural Using: Bromine Monochloride
Authors: Shukla V K S , Shukla S
Published: July 2006

A simple micro procedure for the estimation of furfural with bromine monochloride has been presented. A 2–10mg sample dissolved in distilled water is reacted with a known excess of bromine monochloride in acetic acid in an ice bath, and the excess reagent is back titrated iodometrically. The maximum deviation in the results is ±0.90%.
The Synthesis of 4-Acetylaminoimidazole-5-sulfonamide and 1-Acetyl-5-acetylimidazole-4-sulfonamide
Authors: Robinson B , Zubair M Uppal
Published: July 2006

The synthesis of mono- and di-, N-acetyl derivatives of 5-aminoimidazole-4-sulfonamide, from 5-nitroimidazole-4-sulfonamide, as analogues of 5-amino-1′-ribonucleotyl)imidazole-4-carboxamide, is described.
Improvement of Zone-melting Apparatus: A New Apparatus with a High-precision Heater-temperature-controlling Mechanism
Authors: Ishizuka Yasuko
Published: July 2006

A new zone-melting apparatus with a high-precision heater-temperature-controlling mechanism has been designed and constructed. The apparatus can control the width of several melting zones at an equal temperature and thus can obtain smooth concentration profiles after zone refining. The effect of zone refining with this apparatus was examined with fair success, using phenanthrene and naphthalene as samples.
Mössbauer Absorption Spectra of 119Sn in Single Crystals of (CH3)2SnF2 and (CH3)2SnCl2
Authors: Negita Hisao , Boku Ryukei , Nakamura Makoto , Ichiba Sumio
Published: July 2006

The Mössbauer absorption spectra of 119Sn in single crystals of (CH3)2SnF2 and (CH3)2SnCl2 have been studied as a function of the orientation angles of the incident unpolarized gamma-ray beam with respect to the crystal axes, taking the absorber thickness effect into account. The analysis of the intensity ratios of the quadrupole splitting doublet yields the asymmetry parameter (η) and the orientation of the principal axes of the electric-field gradient with respect to the crystal axes. The value of η in (CH3)2SnCl2 at 135 K was about 0.4, less than the value published previously. The sign of the 119Sn quadrupole coupling constant (e2qQ) in these compounds was found to be positive, as has been reported before.
Excited States of N-Salicylidenealkylamines Chelating to Zinc(II)
Authors: Ohno Takeshi , Kato Shunji , Takeuchi Akira , Yamada Shoichiro
Published: July 2006

For several different forms of N-salicylidenealkylamines (Schiff bases), the absorption and emission spectra, and the yields, lifetimes, and polarizations of the emissions were measured. The neutral Schiff bases exist in two forms, the enolimine and the ketoamine, in an alcoholic solution. All anions of the Schiff bases emit a moderate fluorescence at room temperature and a strong fluorescence and a very weak phosphorescence at 77K. Chelating to Zn2+ and Be2+, they strongly emit a fluorescence and phosphorescence similar to those of the free anions. In the bis-bidentate complexes, the phosphorescence increases and the fluorescence decreases compared to those of the mono-bidentatc complexes—this change in the emission yields may be due to the increase in the intersystem crossing rate, enhanced by an interaction between the ligands perpendicular to each other.
Reaction of Pyridine Bases with Carboxylic Acids in Benzene
Authors: Hirose Katsumi , Tanaka Motoharu
Published: July 2006

The reaction of pyridine bases with aliphatic monocarboxylic acids has been studied by means of the partition method. Partition was carried out at 25 °C between benzene and 0.10 mol dm−3 (Na, H) ClO4 aqueous solution, the total concentration of pyridine base and that of carboxylic acid being less than 2×10−2 mol dm−3 and 1.0 mol dm−3, respectively. Both (1:1) and (1:2) complexes (base to acid ratio) are formed in benzene, (1:3) complex being additionally formed only for 2,4,6-trimethylpyridine. A linear free energy relationship is observed between the formation of the (1:1) and (1:2) complexes and the protonation in water of the corresponding bases except for sterically crowded 2,6-dimethyl derivatives of pyridine. The structure of the (1:2) and (1:3) complexes is discussed.
Studies of the Ruthenium Complexes. XIII. Kinetic Studies of Electrontransfer Reactions between Aquapentaammineruthenium(II) and Halopentaammineruthenium(III) Comlexes
Authors: Ohyoshi Akira , Yoshikuni Kenichiro , Ohtsuyama Hidetoshi , Yamashita Tomohisa , Sakaki Shigeyoshi
Published: July 2006

Kinetic measurements of the electron-transfer reactions from Ru(OH2)(NH3)52+ to RuX(NH3)52+, where X=Cl, Br, and I, have been made in aqueous solutions. The reaction rate is independent of the hydrogen-ion concentration, while it is greatly influenced by the ionic strength of the reaction solution. The rate constants were determined to be 147, 172, and 293 M−1s−1 for the reaction systems of chloro- bromo- and iodopentaammineruthenium(III) ions respectively at 25 °C in a solution with an ionic strength of 0.0944 M. The activation parameters, (ΔH\eweq kcal mol−1, ΔS\eweq cal K−1 mol−1), were (19.4, 16), (18.9, 15), and (11.2, −10) respectively, for the same systems. From the facts that the reaction rate decreases in the order of I>Br>Cl and that the ionic strength of the solution strongly affects the reaction rate, it may be concluded that the present electron-transfer reactions proceed by means of an outersphere-type mechanism.
A Study of the Structures of Aluminum Complexes with Isopropoxy and Methyl Groups Using Pulsed NMR and Chemical Ionization Mass Spectrometry
Authors: Uetsuki Masao , Fujiwara Yuzuru
Published: July 2006

The structures of aluminum complexes formed by the reaction of aluminum isopropoxide with trimethylaluminum was investigated by measuring the spin-lattice relaxation times, T1 for 1H and T1* for 27Al. The motion of the ligand of the complexes reflected upon the value of T1, which was about twice as long at the terminal position as at the bridge position, and decreased with increasing molecular weight. Coordination symmetry about the aluminum nucleus of the complexes governed the value of T1*, which was about ten times as long at the center of the tetrameric complexes as at the wing of the dimeric complexes. The 13C NMR signals of the isopropoxy group varied with the configuration of the ligands, while those of the methyl group were either broad or not observable. Chemical ionization mass spectra of the complexes supported the tetrameric and the dimeric structures determined from the results of NMR measurements.
Polymer-supported Trichlorotitanium(III) Complexes and Their Dioxygen Adducts
Authors: Chimura Yasuo , Beppu Masazo , Yoshida Satohiro , Tarama Kimio
Published: July 2006

Various polymer-supported trichlorotitanium(III) (TiCl3) complexes were prepared in pyridine or THF from TiCl3 and copolymers composed of 4-vinylpyridine (10, 20, and 65 mol%), divinylbenzene (0 and 20 mol%), and styrene. The ESR technique was employed for structural studies of titanium(III) species and their dioxygen adducts contained in the supported complexes. The supported complexes contained, as titanium(III) species, mainly (>88%) mixtures of TiCl3(pyr)nL3−n (n=1, 2, and 3), where pyr is a pyridyl group of the supports and L is a molecule of the solvents used in preparation. The relative amounts of the species having smaller n values increased with cross-linking, with a decrease in the content of pyridyl groups, and with pretreatment with tetra-chlorotitanium(IV) (TiCl4). On exposure to oxygen the supported complexes gave two or three kinds of dioxygen adducts (Ti(IV)–O2−) characterized by g1 the principal g value along the axis of O–O bond. The g1 values of three dioxygen adducts α, β and γ were 2.027–2.028, 2.022–2.024, and 2.017–2.018, respectively. The probable structures of α, β, and γ, when L is THF, are [TiCl2(pyr)3(O2)]Cl, TiCl3(pyr)2(O2), and TiCl3(pyr)L(O2), respectively, their precursors being the titanium(III) species having the n values of 3, 2, and 1, respectively.
Peptides. VI. Some Oxime Carbonates as Novel t-Butoxycarbonylating Reagents
Authors: Itoh Masumi , Hagiwara Daijiro , Kamiya Takashi
Published: July 2006

Several t-butoxycarbonyl derivatives of oximes were prepared through the corresponding oxime chloroformates. Of these, diethyl (t-butoxycarbonyloxyimino)malonate and 2-(t-butoxycarbonyloxyimino)-2-phenylacetonitrile were utilized for the preparation of t-butoxycarbonylamino acids under various conditions. The results are summarized in a table.
The Reactions of Carbonimidoyl Dichlorides with Metal Thioacetates, Acetates, Thiocyanates, and Selenocyanate
Authors: Tanaka Sakuya , Uemura Sakae , Okano Masaya
Published: July 2006

The reactions of carbonimidoyl dichlorides with potassium thioacetate and thiocyanate in tetrahydrofuran afford the corresponding isothiocyanates. Similarly, the reaction with potassium selenocyanate gives isoselenocyanates. Thallium (I) acetate reacts with phenylcarbonimidoyl dichloride with greater facility than potassium acetate to give a mixture of phenyl isocyanate and acetanilide in which the latter is predominant. A displacement of one chlorine atom in the carbonimidoyl dichlorides by a SAc, OAc, SCN, or SeCN group, followed by elimination of AcCl or CNCl, has been proposed as a reasonable reaction path.
Extractive Spectrophotometric Determination of Mercury with Thiobenzoylacetone; Analysis of Waste Water
Authors: Murti M V R , Khopkar S M
Published: July 2006

Thiobenzoylacetone was used for the extraction and spectrophotometric determination of mercury(II). The complex quantitatively extracted at pH 4.0 with 10 ml of 0.001 M reagent in benzene. After removing the excess of the reagent with the buffer solution of pH 12.0, the complex was measured at 345 nm against reagent blank prepared similarly. The system adhered to Beer’s law in the concentration range of 0.6 to 12.1 μg of mercury per ml. The molar extinction coefficient was 1.7×104 and the sensitivity was 0.011 μg/cm2. The complex was stable for 48 h. The extraction was quantitative within 10 min of equilibbrium. It was possible to determine mercury in the presence of a large number of ions (1 : 1000). The method was found to be applicable to the analysis of waste water from chloro-alkali industries.
Benzoyl-β-alaninato Nickel(II) Complexes. The Amino Effect on the Amino Acid Coordination around the Nickel Ion
Authors: Marcotrigiano Giuseppe , Menabue Ledi , Pellagani Gian Carlo
Published: July 2006

A compound of the type Ni(Bz-β-ala)2·2H2O (Bz-β-ala=benzoyl-β-alaninate anion) and its amine adducts of the type Ni(Bz-β-ala)2Bn·xH2O (n=1; B=piperazine (pipz), 1,10-phenanthroline (o-phen) and x=2; n=1, B=2,2′-bipyridine (2,2′-bpy) and 4,4′-bipyridine (4,4′-bpy) and x=4; n=2, B=N-methylpiperazine (CH3-pipz), morpholine (morph), pyridine (py), 3-methylpyridine (3-pic) and 4-methylpyridine (4-pic) and x=2; n=3, B=en, and x=0) were prepared. Each complex was characterized by elemental analysis, solid spectroscopy and magnetic moment. All the complexes are six-coordinated and the presence of NiO6 and NiN6 chromophores for Ni(Bz-β-ala)2·2H2O and Ni(en)3(Bz-β-ala)2 complexes respectively and of NiO4N2 chromophores for the amine adducts is suggested. In all the complexes the amino acid appears to act as a bidentate ligand toward the carboxyl group. A ligand field strength in the aromatic heterocyclic amine adducts was found greater than in the aliphatic heterocyclic amine adducts. The amine adducts complexes appear to dissociate in solution with a change of the donor site, without changing in the stereochemistry, around the nickel ion.
The Effect of Urea on the First and Second CMC’s of Aqueous Solutions of Sodium and Lithium Dodecyl Sulfates
Authors: Kodama Michiko , Boku Ryukei , Ishida Toshio , Miura Masaji
Published: July 2006

The effect of urea on the 1st and 2nd CMC’s of aqueous solutions of sodium and lithium dodecyl sulfates was investigated by the measuments of electric conductivity. The results were discussed in terms of the breaking effect of urea on the water structure not only around the hydrocarbon chains, but also around the counter ions of these surfactants.
Hydrogen-Deuterium Exchange Reaction via β-Sulfinyl Carbanion. Neighboring Sulfur Participation in Carbanion Formation
Authors: Koyanagi Tohru , Hayami Jun-ichi , Kaji Aritsune
Published: July 2006

The rate of base-catalyzed H-D exchange reaction of substituted cyclopropanes and cyclohexanes containing sulfur atom at the β-position of reaction center was investigated. Neighboring sulfur participation in stabilization of the carbanion was suggested in the case of ethyl trans-2-(phenylthio)cyclopropanecarboxylate.
The Action of Malononitrile and Ethyl Cyanoacetate on Diphenylcydopropenone
Authors: Agranat Israel , Boyd Gerhard V , Wirt Mark A
Published: July 2006

Diphenylcydopropenone reacts with malononitrile in the presence of ethanolic sodium methoxide to yield, after acidification, (E)-1,1-dicyano-2-hydroxy-3,4-diphenyl-1,3-butadiene (1a); an analogous product, ethyl (2Z, 4E)-2-cyano-3-hydroxy- 4,5-diphenyl- 2,4-pentadienoate (1b), is formed from ethyl cyanoacetate.
Polarography of α-Keto Acids in Aqueous and Nonaqueous Solutions
Authors: Ohmori Mitsuaki , Takagi Masanosuke
Published: July 2006

Phenylglyoxylic acid (I), phenylpyruvic acid (II), and pyruvic acid (III) were polarographically studied in buffer solutions and in DMF. Their reduction waves were reinvestigated in a wider pH range. Cyclic voltammetry showed that most electrode reactions of these acids in acidic pH are irreversible. pH-Dependence of E1⁄2 and limiting current was studied. The observed decrease of the limiting currents of II and III in the strongly alkaline region was attributed to the dissociation of their corresponding enol forms. The i-E curves of these acids in DMF showed successive poorly-defined reduction waves, while those of the corresponding tetraethylammonium salts (TEA salts) were found to be much simpler in shape. A small oxidation wave was also observed with TEA salts of II and III, suggesting the presence of the enol form in DMF. The reduction products of I and its salt in DMF were studied by means of controlled potential electrolysis and NMR-spectroscopy. The electrode reaction mechanism of α-keto acids in nonaqueous solution is discussed, emphasizing the role of the free acid form as a proton-donor and the formation of a radical anion followed by a disproportionation reaction.
The Correlation of Steric Effects and Equilibrium Constants Evaluated from Lanthanoid-induced 1H Shifts in Aniline Derivative–Eu(fod)3 Systems
Authors: Hirayama Masatoshi , Ishida Norio
Published: July 2006

The equilibrium constants, K1 and K2, between a series of o- and N-substituted anilines and Eu(fod)3 in CCl4 were evaluated using a four-parameter analysis of lanthanoid-induced shifts. It was found that the order of magnitudes of the values of K corrected for the effect of the pKa-value well corresponds to the accessibility of the nitrogen lone-pair to the Eu ion on the complexation.