Simple preparation and catalytic activity of Pd particles dispersed mesoporous carbons from poly(VDC/MA) containing Pd and Y compounds

We report a simple preparation of Pd particles dispersed mesoporous carbons. The carbons were prepared by steam activation of carbonized vinylidene chloride/methyl acrylate copolymer (poly(VDC/MA)) containing yttrium acetylacetonate (Y(acac)(3)) and palladium acetylacetonate (Pd(acac)(2)). The resulting carbons consist of high contents of mesopore and uniformly dispersed fine Pd particles. We measured the catalytic activities of the carbons obtained for hydrogenation of methyl linoleate. The Pd particles dispersed in mesoporous activated carbons obtained from poly(VDC/MA) containing both Y(acac)(3) and Pd(acac)(2) showed high catalytic activities, compared with the microporous activated carbon obtained from poly(VDC/MA) containing only Pd(acac)(2). Especially Pd particles dispersed in mesoporous carbons exhibited excellent selectivity for hydrogenation of diene (methyl linoleate) to monoene (methyl oleate).     

Reactions of oxalyl chloride with 1,2-cycloalkanediols in the presence of triethylamine

The relationship between the product patterns and the configurations of 1,2-cycloheptane- and 1,2-cyclooctanediols 9 in the cyclocondensations with oxalyl chloride in the presence of triethylamine at 0 degrees C has been shown analogous to that obtained for 1,2-disubstituted acyclic ethylene glycols 1: cis-1,2-cyclooctanediol (9f) produced the cyclic oxalate 14f as the major product, while trans-1,2-cycloheptanediol (9e) and trans-1,2-cyclooctanediol (9g) formed the cyclic carbonates 12e, g as the major products. On the other hand, the cyclic oxalates 14a-d were formed as the major products from 1,2-cyclopentane- and 1,2-cyclohexanediols regardless of the configuration. These results can be accounted for by assuming the boat-like transition states for cyclizations of the half esters of comparatively rigid five- and six-membered diols 9a--d. The cyclic oxalates 14a, c may be directly formed through the resulting tetrahedral intermediates from cis-diols (9a,c), and the cyclic carbonates 12a,c as the minor products after ring inversion of the tetrahedral intermediates. The tetrahedral intermediates from the trans-isomers 9b, d cannot undergo ring inversion, producing no traces of the cyclic carbonates 12b, d.     

Some aspects of plasma copolymerization of acetylene with N2 and/or water

Plasma polymerizations of mixture of acetylene-N₂, acetylene-H₂O, were investigated by using an electrodeless glow discharge from a 13.5-MHz radiofrequency source. Properties of plasma polymers were examined as functions of mole ratios of N₂ and/or H₂O to acetylene. The concentration of trapped free radicals and the internal stress in a plasma polymer decreased as the mole ratio of N₂ or H₂O increased. Water showed the most pronounced effects in those properties at the mole ratio of 0.3. Gas permeabilities increased by the copolymerization of N₂ and/or H₂O. Surface energies were also investigated by analysis of contact angles of liquids. Copolymerization of N₂ caused a remarkable increase in polar contribution of surface energy. Some fundamental aspects of flow-rate pressure relationship of mixed gases are presented.     

Structure and dioxygen-reactivity of copper(I) complexes supported by bis(6-methylpyridin-2-ylmethyl)amine tridentate ligands

The structure and dioxygen-reactivity of copper(I) complexes R supported by N,N-bis(6-methylpyridin-2-ylmethyl)amine tridentate ligands L2R[R (N-alkyl substituent)=-CH2Ph (Bn), -CH2CH2Ph (Phe) and -CH2CHPh2(PhePh)] have been examined and compared with those of copper(I) complex (Phe) of N,N-bis[2-(pyridin-2-yl)ethyl]amine tridentate ligand L1(Phe) and copper(I) complex (Phe) of N,N-bis(pyridin-2-ylmethyl)amine tridentate ligand L3(Phe). Copper(I) complexes (Phe) and (PhePh) exhibited a distorted trigonal pyramidal structure involving a d-pi interaction with an eta1-binding mode between the metal ion and one of the ortho-carbon atoms of the phenyl group of the N-alkyl substituent [-CH2CH2Ph (Phe) and -CH2CHPh2(PhePh)]. The strength of the d-pi interaction in (Phe) and (PhePh) was weaker than that of the d-pi interaction with an eta2-binding mode in (Phe) but stronger than that of the eta1 d-pi interaction in (Phe). Existence of a weak d-pi interaction in (Bn) in solution was also explored, but its binding mode was not clear. Redox potentials of the copper(I) complexes (E1/2) were also affected by the supporting ligand; the order of E1/2 was Phe>R>Phe. Thus, the order of electron-donor ability of the ligand is L1Phe相似文献   

Retention,enantioselectivity and enantiomeric elution order of propranolol and its ester derivatives on an alpha1-acid glycoprotein-bonded column

Summary The retention, enantionselectivity and enantiomeric elution order of racemic propranolol (PP) and its ester derivatives (O-acetyl,-propionyl,-butyrul and-valeryl PP) on an ₁-acid glycoprotein (AGP)-bonded column have been investigated by changing eluent composition (eluent pH, buffer concentration, type and content of organic modifier). The retention of these cationic solutes, PP and its ester derivatives, was influenced by eluent pH, ionic strength and organic modifier content. The enantioselectivity was dependent on eluent pH and type of organic modifier. Reversal of the enantiomeric elution order of ester derivatives of PP (O-propionyl-butyryl) and-valeryl PP) occurred around eluent pH 6–7. These results suggst that chiral recognition or binding properties may be altered by the change in eluent composition, espeically eluent pH and type of organic modifier.     

Liquid chromatographic determination of penicillins by postcolumn degradation with sodium hypochlorite using an hollow-fibre membrane reactor

A sensitive, high-performance liquid chromatographic method involving postcolumn degradation with sodium hypochlorite and using a hollow-fibre membrane as a reactor is described for the determination of penicillins. Penicillins were separated on a C18 column followed by postcolumn reaction with sodium hypochlorite and sodium hydroxide using aminated and sulphonated hollow-fibre membrane reactors immersed in each solution, and detected at 270-280 nm based on the UV absorbances of the degradation products. At penicillin concentrations of 2 micrograms/ml, the precisions (relative standard deviation) were 2.28-4.78%. The detection limits of the proposed method were 2.5-25 ng for each penicillin at a signal-to-noise ratio of 3. Ampicillin and its metabolites [(5R,6R)-ampicilloic acid, the (5S,6R)-epimer and (2R)-pierazine-2',5'-dione] in human serum and urine were simultaneously determined by this method.     

Hydrogels of poly(hydroxyethyl methacrylate) and hydroxyethyl methacrylate—glycerol monomethacry-late copolymers

Hydrophilic three-dimensional polymer networks (hydrogels) were prepared from hydroxyethyl methacrylate (HEMA) and the copolymer HEMA and glycerol monomethacrylate (GMMA). The equilibrium water content of the hydrogels in water was investigated as a function of the initial dilution of the polymerization mixture, the type of solvent, and the hydrophilicity of the polymer. The initial dilution was found to have a decisive effect on the swelling or deswelling of hydrogels after the completion of the gel formation. With relatively less hydrophilic hydrogels, there is a critical initial dilution to produce the gel which does not swell or deswell in water after the gel formation. This “isovolumic” initial dilution shifts toward a higher dilution as the hydrophilicity of the hydrogels increases; however, when hydrophilicity of the polymer rises above a certain point, gels always swell in water. Permeability of oxygen through hydrogels was also studied.     

New asymmetric reactions of 2-formyl- and 2-acyl-1-[(2,4, 6-triisopropylphenyl)sulfinyl]naphthalenes via diastereomeric rotamers

Nucleophilic reactions with Grignard reagents and the Mukaiyama aldol reactions of the naphthaldehydes having the (2,4, 6-triisopropylphenyl)sulfinyl group produced products with high stereoselectivity. In these reactions, the stereochemistry of the major products changes depending on the Lewis acids used. Reduction of the 2-acyl-1-[(2,4,6-triisopropylphenyl)sulfinyl]naphthalenes also proceeds with high stereoselectivity but with a different stereochemistry depending on the reducing agents. We have demonstrated, by the mechanistic consideration based on the X-ray crystal structures as well as the (1)H and (13)C NMR spectral data, that the extremely high and specific stereoselectivities of these reactions are due to the predominant rotamer around the C(naph)-S axis. Synthesis of enantiomerically pure 2-naphthylmethanol is provided as an example.     

CO2 laser Stark spectroscopy of the Coriolis-coupled ν2 and ν5 bands of CD3Br

The ν₂ (CD₃ symmetrical deformation) and ν₅ (CD₃ degenerate deformation) fundamental bands of CD₃Br were studied by 9.4- and 10.4-μm CO₂ laser Stark spectroscopy. Stark resonances originating from 28 and 53 rovibrational transitions of the ν₂ and ν₅ bands, respectively, were assigned for each of the isotopic species, CD₃⁷⁹Br and CD₃⁸¹Br. These two bands were simultaneously analyzed with explicit inclusion of the ν₂-ν₅ Coriolis interaction, yielding precise molecular constants in the ν₂ and ν₅ excited states as well as the Coriolis coupling constant. The molecular constants obtained are consistent between the two isotopic species and are in good agreement with the results of high-resolution infrared studies. The band origins and dipole moments are

     

50.

Alkyl Ammonium Ion Selectivity of Hexahomotrioxacalix[3]arene Triamide Derivative having the Intramolecular Hydrogen-Bonding Group     

Takehiko Yamato  Fumika Kitajima  Jeong Tae Gil 《Journal of inclusion phenomena and macrocyclic chemistry》2005,53(3):257-262

The lower rim functionalized hexahomotrioxacalix[3]arene triamide 4 with cone-conformation was synthesized from triol 1 by a stepwise reaction. The different extractability for alkali metal ions, transition metal ions, and alkyl ammonium ions from water into dichloromethane is discussed. Due to the strong intramolecular hydrogen bonding between the neighboring NH and CO groups in triamide 4, its affinity to metal cations was weakened. Triamide 4 shows a single selectivity to n-BuNH₃⁺. The anion complexation of triamide 4 was also studied by ¹H NMR titration experiments. Triamide 4 binds halides through the intermolecular hydrogen bonding among the NH hydrogens of amide in a 1:1 fashion in CDCl₃. The association constants calculated from these changes in chemical shifts of the amide protons are K_a = 223 M⁻¹ for Cl⁻ and K_a = 71.7 M⁻¹ for Br⁻. Triamide 4 shows a preference for Cl⁻ complexation than Br⁻ complexation.     

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		CD379Br		CD381Br
$\text{ν}{}_2$		991.396 82 (18)		991.388 46 (17)		cm?1
$\text{ν}{}_5$		1055.469 00 (12)		1055.466 32 (12)		cm?1
$\text{μ}{}_0$		1.830 42 (52)		1.829 84 (47)		D
$\text{μ}{}_2$		1.829 93 (48)		1.829 57 (46)		D
$\text{μ}{}_5$		1.832 23 (60)		1.831 19 (56)		D

Alkyl Ammonium Ion Selectivity of Hexahomotrioxacalix[3]arene Triamide Derivative having the Intramolecular Hydrogen-Bonding Group

The lower rim functionalized hexahomotrioxacalix[3]arene triamide 4 with cone-conformation was synthesized from triol 1 by a stepwise reaction. The different extractability for alkali metal ions, transition metal ions, and alkyl ammonium ions from water into dichloromethane is discussed. Due to the strong intramolecular hydrogen bonding between the neighboring NH and CO groups in triamide 4, its affinity to metal cations was weakened. Triamide 4 shows a single selectivity to n-BuNH₃⁺. The anion complexation of triamide 4 was also studied by ¹H NMR titration experiments. Triamide 4 binds halides through the intermolecular hydrogen bonding among the NH hydrogens of amide in a 1:1 fashion in CDCl₃. The association constants calculated from these changes in chemical shifts of the amide protons are K_a = 223 M⁻¹ for Cl⁻ and K_a = 71.7 M⁻¹ for Br⁻. Triamide 4 shows a preference for Cl⁻ complexation than Br⁻ complexation.