Showing papers in "Bulletin of the Chemical Society of Japan in 1990"

The preparation of alkyltrimethylammonium-kanemite complexes and their conversion to microporous materials.

Abstract: Single layered polysilicate kanemite (NaHSi2O5·3H2O) was allowed to react with alkyltrimethylammonium chloride solutions to form alkyltrimethylammonium–kanemite complexes. During the organic intercalation, the SiO2 layers in the complexes were condensed to form three-dimensional SiO2 networks. The calcined products of the complexes had micro pores 2–4 nm in diameter, and the surface areas were ca. 900 m2g−1. The pore size of the calcined products was altered with the variation in the alkyl-chain length of the alkyltrimethylammonium ions employed.

Electrochemical Reduction of Carbon Dioxide at Various Metal Electrodes in Aqueous Potassium Hydrogen Carbonate Solution

Abstract: The electrochemical reduction of carbon dioxide at various metallic electrodes was carried out potentiostatically at 298 K in aqueous potassium hydrogen carbonate solution in order to make clear the electrocatalysis of metals in reduction of CO2. It was found that metals used as electrodes are classified into four groups according to their main products from CO2, i. e., metallic In, Sn, Hg, and Pb are selective for the production of formic acid; metallic Ag and Au are selective for the formation of carbon monoxide; metallic copper has the highest electrocatalytic activities in formation of hydrocarbons, aldehydes, and alcohols; and metallic Al, Ga, Group a, and Group VIII elements except Pd have scarce electrocatalytic activity in reduction of CO2. Effects of the reduction potential on products from CO2 were also examined in detail for Zn, In, and Au electrodes which have some interesting properties.

Thermally Irreversible Photochromic Systems. Reversible Photocyclization of 1,2-Bis(benzo[b]thiophen-3-yl)ethene Derivatives

Abstract: 1,2-Bis(benzo[b]thiophen-3-yl)ethene derivatives, which possess thermally irreversible and fatigue resistant photochromic properties, were synthesized, cis-1,2-Dicyano-1,2-bis(2-methylbenzo[b]thiophen-3-yl)ethene 1a and 2,3-bis(2-methylbenzo[b]thiophen-3-yl)maleic anhydride 2a underwent reversible photocyclization to produce red-colored closed-ring forms with λmax at 507 nm and 544 nm, respectively. The closed-ring forms were stable for more than 3 weeks at 80 °C. The coloration/decoloration (ring closure/opening)cycles were able to be repeated more than 104 times with keeping the adequate photochromic performance.

Homocoupling of Aryl Halides Using Nickel(II) Complex and Zinc in the Presence of Et4NI. An Efficient Method for the Synthesis of Biaryls and Bipyridines

Abstract: Reduction of NiX2(PPh3)2 with zinc in the presence of Et4NI gives a nickel catalyst which has been proven to be useful for the coupling of aryl halides. This nickel catalyst can be prepared in THF without an additional triphenylphosphine and is effective for the homocoupling of aryl chlorides, bromides, and iodides to produce biaryls and bipyridines in good yields. The reported new approach provides a simple access to novel derivatives of biaryls and bipyridines.

Crystal and electronic structures of (BEDT-TTF)2(MHg(SCN)4)(M=K and NH4).

Abstract: The crystal structures of (BEDT–TTF)2[MHg(SCN)4] (M=K at 298 and 104 K and M=NH4 at 298 K) were determined by X-ray analyses. A donor layer and an anion sheet stack alternately along the b-axis. The packing pattern of the donor is close to α-phase, while an anion sheet constructs a thick two-dimensional polymer plane parallel to (010). The linkage of (Remark: Graphics omitted.) (or NH4) (Remark: Graphics omitted.) in an anion sheet is very unique. The band structure calculation indicates both a closed and an open Fermi surfaces, resembling that of κ-(BEDT–TTF)2[Cu(NCS)2].

Trimethylsilyl Derivatives of Alkyltrimethylammonium–Kanemite Complexes and Their Conversion to Microporous SiO2 Materials

Abstract: Alkyltrimethylammonium–kanemite complexes, having three dimensional SiO2 networks, were allowed to react with a trimethylsilylating reagent to form the trimethylsilylated derivatives. The three dimensional SiO2 networks were retained after trimethylsilylation. The calcined products obtained from the trimethylsilylated products had about 840–880 m2 g−1 in specific surface areas and micro pores with 22–33 A in average pore diameter. These values were slightly smaller than those of the calcined products obtained from alkyltrimethylammonium–kanemite complexes, which indicated the effect of the trimethylsilyl groups.

Preparation and characterization of optically active Schiff base-oxovanadium(IV) and -oxovanadium(V) complexes and catalytic properties of these complexes on asymmetric oxidation of sulfides into sulfoxides with organic hydroperoxides.

Abstract: Oxovanadium(V) complexes, VVO (Schiff base)Y (Y=ClO4, Cl, NO3), with quadridentate Schiff base ligands derived from optically active 1,2-diamines and salicylaldehyde or its derivatives were prepared by oxidizing the corresponding VIVO (Schiff base) with CeIV in acetonitrile followed by the addition of HY. The complexes were characterized by their 1H NMR, IR, UV-Vis, and circular dichroism spectra, and electrochemistry. Reversible reduction potentials (V5+/V4+) obtained by cyclic voltammetry for a series of oxovanadium(V) complexes with Schiff base ligands derived from 5-substituted salicylaldehydes showed a linear dependence on the Hammett parameter. Both the vanadium(IV) and the vanadium(V) complexes catalyze asymmetric oxidation of sulfides into the corresponding sulfoxides with organic hydroperoxides. The oxovanadium(IV) complex catalysts gave much better asymmetric induction than the oxovanadium(V) complex catalysts and in most cases the enantiomeric excess (ee) ranged between 20 and 40%. In the react...

Convenient and efficient tosylation of oligoethylene glycols and the related alcohols in tetrahydrofuran-water in the presence of sodium hydroxide

Abstract: Oligoethylene glycols and some related alcohols were efficiently tosylated with p-toluenesulfonyl chloride in a tetrahydrofuran–water (1:1) mixture in the presence of excess sodium hydroxide. This method is advantageous over the conventional tosylation in pyridine both regarding the work-up procedure, the yield, and the purity of the product, and may be potentially useful for the tosylation of certain acid-labile alcohols.

The Application of ESR Spin-Trapping Technique to the Evaluation of SOD-like Activity of Biological Substances

Abstract: The SOD-like activity of several biological substances was evaluated by an ESR spin-trapping technique. Superoxide radicals (O2\ewdot) were supplied enzymatically from a hypoxanthine–xanthine oxidase reaction to the evaluating system. By using a spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO), the generated O2\ewdot was trapped stoichiometrically (1:1) as the spin adduct of O2\ewdot (DMPO–O2−). When biological substances were added to the system, a decrease in the ESR signal intensities of the adducts was observed. This phenomenon could be explained as being an inhibition of adduct formation, and related to the reactivity of added biological substances with O2\ewdot, called an SOD-like activity. By the method of kinetic competition with a 50% inhibitory dose (ID50), the second-order rate constant for the reaction between O2\ewdot and biological substance was determined. These rate constants can be used as a measure of the reactivity.

Asymmetric trasformation of symmetrical epoxides to allylic alcohols by lithium (S)-2-(N,N-disubstituted aminomethyl)pyrrolidide

Abstract: Enantioselective deprotonation of symmetrical epoxides was studied by using chiral lithium amide, prepared from (S)-2-(N,N-disubstituted aminomethyl)pyrrolidine and butyllithium Chiral allylic alcohols were obtained with moderate to high enantiomeric excesses (ee’s) (41–92% ee) from several cyclic and acyclic epoxides employing lithium (S)-2-(1-pyrrolidinylmethyl)pyrrolidide in tetrahydrofuran (THF) in the presence of 1,8-diazabicyclo[540]undec-7-ene (DBU)

A grignard-type addition of allyl unit to aldehydes by using bismuth and bismuth salt

Abstract: In the presence of metallic bismuth, bismuth(III) chloride–metallic zinc, or bismuth(III) chloride–metallic iron, allylic halides have been found to react with aldehydes under mild conditions to give the corresponding homoallylic alcohols in high yields with high chemo-, regio-, and stereoselectivity. Allylic halides have been also found to react with aldehydes at room temperature in tetrahydrofuran–water by using bismuth(III) chloride–metallic aluminium to afford the expected homoallylic alcohols in high yields.

Synthesis and chemiluminescence of coelenterazine(Oplophorus luciferin) analogues.

Abstract: In the case of chemiluminescence of coelenterazine, effects of conformation rigidity of and hydrogen bonding with the emitter, coelenteramide, on the chemiluminescence efficiency have been examined with several coelenterazine analogues synthesized. Conformational rigidity has a light enhancing effect, whereas decreasing light yield was observed by hydrogen-bond formation with the emitter.

Hydration of oligosaccharides

Abstract: The spin-lattice relaxation times, T1, of H217O have been measured for aqueous solutions of 2 di-, 2 trisaccharides, α-, and γ-c clodextrins as a function of the concentration at 25°C. The dynamic hydration numbers, nDHN, for 17 sugars including monosaccharides were expressed by the linear relation of the mean number of the equatorial OH groups. The second virial coefficients showed a good correlation with nDHN. Though the rotational correlation times, τch, of water molecules in the cosphere of sugar molecules increased with increasing the number of equatorial OH groups for monosaccharides, those for trisaccharides and cyclodextrins showed almost constant values. The relation between the values of the limiting diffusion coefficients and nDHN for sugars was found to be expressed by two lines with a large negative slope for mono- and di- saccharides, and a small negative slope for trisaccharides and cyclodextrins.

“pKa” of Calixarenes and Analogs in Nonaqueous Solvents

Abstract: The acid dissociation constants (Kapp) of p-t-butylcalix[n]arenes (1n: n=4, 6, and 8), O-methylated p-t-butylcalix[4]arene (2Men), and their noncyclic analogs (3n) were estimated in THF at 25°C. As pH indicators, Et4N+ salts of p-nitrophenolate, 2,4-dinitrophenolate, and picrate were employed. The pKapp values for 1n were lowered by at least four pK units from that of p-t-butylphenol because of strong intramolecular hydrogen-bonding interactions. Compounds 2n involved both the strong and weak hydrogen bonds: the proton in the strong hydrogen bond showed the acidity comparable with that of 1n whereas that in the weak hydrogen bond showed the relatively high pKapp. These properties were discussed in relation to δOH (chemical shift in 1HNMR) and νOH(OH vibration band in IR). This is the first systematic discussion on “pKa” of p-t-butylcalix[n]arenes.

Synthetic Inorganic Ion-Exchange Materials. LVIII. Hydrothermal Synthesis of a New Layered Lithium Titanate and Its Alkali Ion Exchange

Abstract: A new crystalline hydrous lithium titanate, (Li1.81, H0.19)Ti2O5·2.2H2O, was synthesized hydrothermally at 190 °C by a reaction of hydrous titanium dioxide with LiOH solution. The compound has a layered structure and showed a C–base-centered orthorhombic system with the lattice constants, ao=16.66±0.02 A, bo=3.797±0.002 A, and co=3.007±0.003 A. The lattice constants were changed to ao=18.08±0.03 A, bo=3.784±0.003 A, and co=2.998±0.002 A upon conversion to the hydrogen form. The 8.5% increase in the ao value along the a axis suggests a layered structure. A hypothetical structure was proposed. The H+ form showed the ion-exchange selectivity at an ionic strength of 0.1 in the order of K+ 6 and Li+

Accurate Determination of NMR Chemical Shifts in Alkali Halides and Their Correlation with Structural Factors

Abstract: High-resolution solid-state NMR spectra of alkali halides have been measured using the magic angle spinning (MAS) of the sample, and chemical shifts of 7Li, 23Na, 87Rb, 133Cs, 35Cl, 79Br, and 127I have been determined accurately. The 39K chemical shifts have been determined by NMR without MAS. As the ratio of the cation radius to the anion radius (Rm) increases, the chemical shifts of halogen nuclei show an upfield shift when Rm 0.6. The chemical shifts of the halogen nuclei are explained in terms of the first and the second nearest neighbor interactions, both of which cause a downfield shift. On the other hand, the chemical shifts of alkali nuclei show a downfield shift for the ratio of the anion radius to the cation radius (Rx) less than 1.6, while they show an upfield shift for Rx>1.6. The chemical shifts of the alkali nuclei are expressed by the sum of the nearest neighbor interaction in the absence of the halogen-halogen interaction and the “isolation ef...

An efficient method for the direct peroxygenation of various olefinic compounds with molecular oxygen and triethylsilane catalyzed by a cobalt(II) complex

Abstract: An efficient method for the direct peroxygenation of various olefinic compounds with molecular oxygen and triethylsilane (Et3SiH) was developed by the use of a catalytic amount of a bis(1,3-diketonato)cobalt(II) complex. According to the above method, 1-phenyl-3-triethylsilydioxybutane (2) was directly produced from 4-phenyl-1-butene (1) by means of a reaction with O2 and Et3SiH at room temperature. Styrene (3) and ethyl acrylate (5a) were also smoothly peroxygenated to give 1-phenyl-1-triethylsilyldioxyethane (4) and ethyl 2-triethylsilyldioxypropionate (6a) by using a small amount of t-BuOOH as an initiator. The successive desilylation of 6a and reduction of the resulting ethyl 2-hydroperoxypropionate (8a) afforded the corresponding alcohol, ethyl lactate (10a), in a high yield. The synthetic utility of the present peroxygenation reaction was demonstrated in the preparation of α-hydroxy esters 10a–e from several α,β-unsaturated esters 5a–e via the corresponding triethylsilyldioxy derivatives.

Femtosecond-picosecond laser photolysis studies on photoreduction process of excited benzophenone with N,N-dimethylaniline in acetonitrile solution.

Abstract: Photoreduction processes of excited benzophenone (BP) by N,N-dimethylaniline (DMA) in acetonitrile solution were studied by means of picosecond-femtosecond laser photolysis and time resolved transient absorption spectroscopy as well as transient photoconductivity measurement. Proton transfer process in the triplet ion pair formed by electron transfer (ET) at encounter between 3BP* and DMA, competing with the ionic dissociation process was observed. It was clearly demonstrated that, in addition to the triplet ion pair, the ion pair produced by the excitation of the CT complex between BP and DMA formed in the ground state and that produced by ET reaction between 1BP* and DMA played important roles in the reaction processes of excited benzophenone. The behaviors of the three kinds of ion pairs were investigated in detail, leading to the elucidation of reaction mechanism of each ion pair. The reactivity characteristic of each kind of the ion pair and its relation to the structure of the ion pair were discussed.

Synthesis and Catalytic Capability of Zeolite-Encapsulated Iron and Manganese Tetramethylporphine Complexes

Abstract: Iron and manganese tetramethylporphine (TMP) complexes were synthesized within the cages in NaY zeolite. The ligation of porphine to the metals enhanced the capability of ion-exchanged zeolite to oxidize saturated hydrocarbons with hydrogen peroxide.

Acidity and Catalytic Activity of Zirconium and Titanium Sulfates Heat-Treated at High Temperature. Solid Superacid Catalysts

Abstract: Acidity and catalytic activity of Zr(SO4)2 and Ti(SO4)2 calcined at 500–800°C were studied. The products obtained by calcination at 725°C for Zr(SO4)2 and at 625°C for Ti(SO4)2 showed the highest activity for the cracking of cumene among samples calcined at other temperatures; the former showed an acid strength of −13.16

Catalytic oxidation-reduction hydration of olefin with molecular oxygen in the presence of bis(1,3-diketonato)cobalt(II) complexes.

Abstract: In the presence of a bis(1,3-diketonato)cobalt(II) complex, various olefins are converted to the corresponding hydrated products according to the Markownikov rule on treatment with molecular oxygen in secondary alcohol (“oxidation–reduction hydration”). Removal of water formed during the hydration reaction, especially by azeotropic method, is remarkably effective to improve yields of the hydrated products based on the cobalt(II) catalyst as bis(trifluoroacetylacetonato)cobalt(II) (Co(tfa)2) or bis(2-ethoxycarbonyl-3-oxobutanalato)cobalt(II) (Co(ecbo)2).

The role of triplet state of nitrospiropyran in their photochromic reaction

Abstract: The effects of intermolecular and intramolecular triplet quenchers and sensitizers on the photochromism of nitrospiropyran have been examined in order to clarify the role of the triplet state (3A*) as well as that of the excited singlet state (1A*). The rates of photocoloration and fatigue were significantly affected: the quenchers retarded both rates, while the sensitizers retarded the former but enhanced the latter rate. It can be concluded that more than 90% of the total amount of photomerocyanin is generated from 1A* in the photostationary state and that fatigue proceeds mainly through 3A*.

Partial molar volumes in aqueous mixtures of nonelectrolytes. IV, aromatic hydrocarbons

Abstract: The densities of binary mixtures of water with benzene, toluene, and ethylbenzene were measured for both ends of the concentration range at 5, 15, 25, 35, and 45 °C. The partial molar volumes were evaluated for both components by assuming a linear correlation of the density with the concentration. The partial molar volumes of the aromatic hydrocarbons (VA) in a water-rich region are smaller than the molar volumes of the respective solutes, but the temperature dependences of the VA are almost the same as the molar expansibilities of the solutes. On the other hand, the partial molar volumes of water (VW) and their temperature dependences in a hydrocarbon-rich region are appreciably larger compared with the molar volume and molar expansibility of pure water, respectively. The results are discussed on the basis of the scaled particle theory and interpreted in terms of the difference of the compressibilities of the solvents. The volumetric behavior of the aromatic hydrocarbons in aqueous solutions does not bea...

Synthesis, Structure, and Magnetism of Binuclear Cu(II)Cu(II), Cu(II)Ni(II), and Ni(II)Ni(II) Complexes Doubly Bridged by Oxymate Groups

Abstract: Binuclear complexes, [Cu(L)Cu(L′)(H2O)2]X2 (H2L=3,3′-trimethylenedinitrilobis(2-butanoneoxime) (H2dopn) or 3,3′-ethylenedinitrilobis(2-butanoneoxime) (H2doen); L′=2,2′-bipyridyl (bpy) or 1,10-phenanthroline (phen); X=ClO4 or NO3), [Ni(dopn)Cu(bpy)(H2O)](ClO4)2, and [Ni(dopn)Ni(bpy)2](ClO4)2, have been prepared and characterized. The structure of [Cu(dopn)Cu(phen)(CH3OH)2](ClO4)2 (di-methanol adduct) has been determined by single crystal X-ray method. The Cu(dopn) molecule coordinates to the second copper(II) ion through the deprotonated oximate oxygens to afford a binuclear structure doubly bridged by the oximate groups in the cis arrangement. The binuclear cation is bent at the oxymate oxygens with a dihedral angle of 26.7(2)°. The binuclear copper(II) complexes show a characteristic visible band of significant intensity (e 2700–2900 dm3 mol−1cm−1) near 22000 cm−1 and a strong intramolecular antiferromagnetic spin-exchange interaction. The exchange integrals (J) are evaluated to be −413.3–−433.0 cm−1. Th...

Nickel-Catalyzed Dehydrogenation of Amines to Nitriles

Abstract: Aliphatic primary amines having α-methylene underwent oxidative dehydrogenation on treatment with NiSO4 as a catalyst and K2S2O8 as an oxidant to give the corresponding nitriles in good yields Ben

Palladium catalyzed direct oxidation of benzene with molecular oxygen to phenol

Abstract: Direct phenol synthesis from benzene is currently one of the most important problems in modern chemistry. We have reported new phenol synthesis from benzene and O2 via direct activation of a C–H aromatic bond by the Pd(OAc)2/phenanthroline catalyst system. The evidence for direct oxidation of benzene by O2 was obtained using 18O and 2H isotopes. The mechanism was proposed on the basis of these results and the reactions of Ph–Pd σ complex intermediates.

Structural, magnetic and spectroscopic characterization of novel di-μ-carboxylato-bridged binuclear copper(II) complexes with 1,10-phenanthroline

Abstract: Bis(μ-carboxylato-O,O′)-diaquabis(1,10-phenanthroline)dicopper(II) dinitrate tetrahydrates, [Cu(RCOO)(phen)(H2O)]2(NO3)2·4H2O, where R=H, CH3, and (CH3)3C, were prepared and characterized by elemental analyses, electronic spectra, magnetic susceptibilities, and X-ray structure analysis. The magnetic susceptibility data conform to the usual dimer equation. The −2J values are 125 cm−1 for formate, 86 cm−1 for acetate, and 99 cm−1 for 2,2-dimethylpropanoate. The crystal structures of [Cu(HCOO)(phen)(H2O)]2(NO3)2·4H2O (1) and [Cu(CH3COO)(phen)(H2O)]2(NO3)2·4H2O (2) were determined by the single-crystal X-ray diffraction method. The crystallographic data are: Compound 1, monoclinic, I2⁄a, a=18.850(2), b=9.775(2), c=17.752(2) A, β=99.03(1)°, V=3230.4(8) A3, Z=4, R=0.055 for 2511 observed unique reflections; Compound 2, monoclinic, C2⁄c, a=18.563(4), b=14.272(5), c=14.126(3) A, β=106.72(2)°, V=3584(2) A3, Z=4, R=0.082 for 2092 reflections. The complexes consist of dimeric [Cu(RCOO)(phen)(H2O)]22+)] cations with ...

A New Photochromic Spiro[3H-1,4-oxazine]

Abstract: A new photochromic spiro[3H-1,4-oxazine] 4 is described. The absorption spectra of 4 have been examined and compared with those of spiro[indoline-naphthoxazine] 1. The colored form of 4 has the absorption maximum shorter than that of 1. Compound 4 showed excellent light fatigue-resistant property.

Liquid/Solid Extraction of Acetylacetone Chelates with Supercritical Carbon Dioxide

Abstract: The solubilities of the acetylacetone chelates in supercritical CO2 (SC-CO2) at 333 K and 9.8–29.4 MPa were strongly influenced by the extraction pressure, and by the nature of the metals and the number of acetylacetone ligands in the chelates. It was found that acetylacetone chelates could be extracted selectively by SC-CO2 treatment because of significant differences in their solubilities in SC-CO2.

Dynamical structures of normal alkanes, alcohols, and fatty acids in the liquid state as determined by viscosity, self-diffusion coefficient, infrared spectra, and 13C NMR spin-lattice relaxation time measurements.

Abstract: The dynamical structures of molecules of normal alkanes (C5–C14) and normal fatty acids (C8 and C9) in the liquid state were estimated through analyses of their self-diffusion coefficients (D), viscosities (η), molar volumes, and 13CNMR spin-lattice relaxation time (T1). The apparent hydrodynamic radius evaluated from D and η for the alkanes was ca. 2.5×10−10 m and that for the fatty acids, ca. 3.1×10−10 m, irrespective of their hydrocarbon chain length: The former value is almost equal to that of the van der Waals radius (2.4×10−10 m) of the cross section of a hydrocarbon chain; the latter is in agreement with that of the normal alcohols reported in a previous paper. It is thus concluded that in the pure liquid of a rod-like compound such as normal alkane, alcohol, and fatty acid, the free rotational (end-over-end) as well as the transverse motion of the rod-like molecule is severely restricted due to the entanglements of the molecules; only a longitudinal translation is allowed. In addition, the infrare...