Permeation of H2, N2, CH4, C2H6, and C3H8 through asymmetric polyetherimide hollow‐fiber membranes

Permeation properties of pure H₂, N₂, CH₄, C₂H₆, and C₃H₈ through asymmetric polyetherimide (PEI) hollow‐fiber membranes were studied as a function of pressure and temperature. The PEI asymmetric hollow‐fiber membrane was spun from a N‐methyl‐2‐pyrrolidone/ethanol solvent system via a dry‐wet phase‐inversion method, with water as the external coagulant and 50 wt % ethanol in water as the internal coagulant. The prepared asymmetric membrane exhibited sufficiently high selectivity (H₂/N₂ selectivity >50 at 25°C). H₂ permeation through the PEI hollow fiber was dominated by the solution‐diffusion mechanism in the nonporous part. For CH₄ and N₂, the transport mechanism for gas permeation was a combination of Knudsen flow and viscous flow in the porous part and solution diffusion in the nonporous part. In our analysis, operating pressure had little effect on the permeation of H₂, CH₄, and N₂. For C₂H₆ and C₃H₈, however, capillary condensation may have occurred at higher pressures, resulting in an increase in gas permeability. As far as the effect of operating temperature was concerned, H₂ permeability increased greatly with increasing temperature. Meanwhile, a slight permeability increment with increasing temperature was noted for N₂ and CH₄, whereas the permeability of C₂H₆ and C₃H₈ decreased with increasing temperature. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 698–702, 2002     

Darstellung,Konfigurationen und NMR-Daten der Säuren CH3(SR)  CHCOOH (R  C6H5, CH2C6H5, CH2COOH)

Preparation, Configurations and N.M.R. Dates of the Acids CH₃(SR)CHCOOH (R  C₆H₅, CH₂C₆H₅, CH₂COOH) The cis and trans isomers of the acids CH₃(SR)CHCOOH (R  C₆H₅, CH₂C₆H₅, CH₂COOH) were prepared by addition of HSR to CH₃CCCOOH in alkaline water solution and by alkaline hydrolysis of CH₃C(SR)₂CH₂COOC₂H₅ (R  C₆H₅, CH₂C₆H₅, CH₂COOC₂H₅). The oxidation products CH₃C(SO₂R)  CHCOOH (R  C₆H₅, CH₂COOH) were also prepared. The n.m.r. dates of the acids were obtained and some relations between them were discussed.     

Synthesis and structure of a mixed valence metal carbitoxide complex: Eu3[O(CH2CH2O)2CH2CH3]4(OC6H3iPr2-2,6)3

The direct reaction of europium metal with HO(CH₂CH₂O)₂CH₂CH₃ followed by treatment with 2,6-ⁱPr₂C₆H₃OH leads to the crystallographically-characterizable, mixed valent carbitoxide product Eu₃[O(CH₂CH₂O)₂CH₂CH₃]₄(OC₆H₃ⁱPr₂-2,6)₃ (1), which contains bridging alkoxide ligands and both terminal and bridging aryloxide ligands.     

Synthesis and characterization of [Pd{PhP(C6H4-2-SCH2Cl)(C6H4-2-S)}(Ph2PCH2CH2PPh2)]Cl: An example of hemilability and dichloromethane activation

The stoichiometric reaction of [Pd{PhP(C₆H₄-2-S)₂}(PPh₃)] (1) with Ph₂CH₂CH₂Ph₂ in dichloromethane (CH₂Cl₂) as solvent, affords complex [Pd{PhP(C₆H₄-2-SCH₂Cl)(C₆H₄-2- S)}(Ph₂PCH₂CH₂PPh₂)]Cl (2). This specie, being the result of the nucleophilic reaction of a de-ligated thiolate moiety from the fragment [Pd{PhP(C₆H₄-2-S)₂}] with dichloromethane (chloromethylation).     

Dinuclear Rhodium Complexes Containing the Diyne 1,4-C6H4(C≡CH)2 and the Isomeric Bisvinylidene 1,4-C6H4(CH=C:)2 as Bridging Units

The reaction of [RhCl(PiPr₃)₂] ( 1 ) with 1,4-C₆H₄(C≡CH)₂ at 0°C leads almost quantitatively to the formation of the bis(alkyne) complex [(PiPr₃)₂ClRh-(HC≡C₆H₄-C≡CH)RhCl(PiPr₃)₂] (2). At elevated temperatures (THF, 60°C) it rearranges to give the isomeric bis(vinylidene) complex [(PiPr₃)₂ClRh-(=C=CH-C₆H₄-CH=C=)RhCl(PiPr₃)₂] (3). A one-pot synthesis of 3 is also described. Treatment of either 2 or 3 with pyridine affords the bis(alkynyl)dihydrido compound [(PiPr₃)₂(py)Cl(H)Rh(-C≡C-C₆H₄-C≡C-)Rh(H)Cl(py)(PiPr₃)₂] ( 4 ) in which both metal centers are octahedrally coordinated. Whereas the reaction of 2 with NaC₅H₅ produces the complex C_sH₅(PiPr₃)Rh(HC≡C-C₆H₄-C≡CH)Rh(PiPr₃)C₅H₅ ( 7 ), the bis(vinyl-idene) isomer C₅H₅(PiPr₃)Rh(=C=CH-C₆H₄-CH=C=)Rh(PiPr₃)C₅H_s ( 8 ) is obtained from 4 and NaC₅H₅. Electrophiles preferably attack the Rh=C bonds of 8 and thus on protonation with CF₃CO₂H the bis(vinyl) complex C₅H₅(PiPr₃)(CF₃CO₂)-Rh(Z,Z-CH=CH-C₆H₄-CH=CH)Rh(O₂CCF₃)(PiPr₃)C₅H_s ( Z-9 ) is formed. In acetone solution, it rearranges to give the E isomer. Reaction of 8 with sulfur affords the bis(thioketene) complex C₅H₅(PiPr₃)Rh(≡²-C,S; η²-C,S-S=C=CH-C₆H₄-CH=C=S)-Rh(PiPr₃)C₅H₅ ( 12 ), for which only one diastereomer is observed. All attempts to prepare mononuclear rhodium compounds containing the diyne HC≡C-C₆H₄-G≡CH or the isomeric vinylidene: C=CH-C₆H₄-G≡CH as ligand failed.     

Study of the preparation of bulk tungsten carbide catalysts with C2H6/H2 and C2H4/H2 carburizing mixtures

The influence of the preparation procedure of tungsten carbide on the mechanism of carburization is discussed. This work is focused on the reduction and the carburization of tungsten trioxide by a mixture of hydrocarbon and H₂ to form WC. Temperature-programmed reaction spectra obtained with CH₄, C₂H₆ and C₂H₄ have been measured. In presence of the CH₄-H₂ mixture, H₂ is the reducing agent and the hydrocarbon is consumed for the carburization whereas C₂H₆ or C₂H₄ participates in the reduction of the tungsten oxide. The temperatures of reduction and carburization are lower by about 150 K using C₂H₆ or C₂H₄ instead of CH₄. Such a decrease of the temperature of reduction of tungsten oxide is needed to avoid the formation of poorly reducible compounds that can occur during the preparation of supported tungsten carbide. Furthermore, the surface area of the resulting carbide is 25 m²/g with C₂H₆ and C₂H₄ and 10 m²/g with CH₄. During the carburization, the deposit of excess carbon on the WC surface is larger with the C₂ hydrocarbons than with CH₄, but it protects the carbide and can be removed by hydrogen treatment. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and nanostructure of [Mo(C6H4O2)3]·2(C4H8N2O) and the synthesis from 1,2-PDA to (C4H8N2O)

Continuing our work on the synthesis of MoO₂L₂ and MoO₃L_AL_B that show excellent anti-cancer activities in vitro, the MoL₃ have been synthesized by the solvothermal reaction of Na₂MoO₄ with catechols and 1,2-DPA in the mixed solvent of MeCN/MeOH. X-ray diffraction revealed that Mo in chiral octahedral geometry coordinate with three catechol ligands formed three five-membered rings, and the [Mo(C₆H₄O₂)₃] are linked by hydrogen bonds Mo(OC₆H₄)O…H–N(C₄H₈O)N–H…O(C₆H₄O)Mo through the by-product (C₄H₈N₂O) that are formed by one 1,2-DPA with one CO₂ on the catalysis of Mo-complex. Also, we have disassembled bulk crystal into nano-aggregates, and under TEM mono-lamella morphology of nanostructures was observed, which agrees well with the previous conclusion that the morphologies of the nano-aggregates are associated with the quantum motifs in their crystal lattices. [Mo(C₆H₄O₂)₃] have also been characterized by UV–vis spectra, cyclic voltammogram and thermogravimetric analysis.     

Synthesis and structural characterizations of organolanthanide complexes with amino-tethered guanidinate ligand (C5H5)2Ln[H2N(CH2)3NC(NHiPr) NiPr)] (Ln = Yb,Y, Er,Dy)

Reaction of N,N′-diisopropylcarbodiimide (ⁱPrNCNⁱPr) with H₂N(CH₂)₃NH₂ and (C₅H₅)₃Ln, give (C₅H₅)₂Ln[H₂N(CH₂)₃NC(NHⁱPr) NⁱPr)] in high yields, indicating that the N–H bonds of one NH₂ group readily add to the CN double bonds of carbodiimide and one cyclopentadienyl group is eliminated to construct a novel amino-tethered guanidinate anionic ligand [H₂N(CH₂)₃N C(NHⁱPr)NⁱPr)]⁻.     

First structurally characterized anion exchange product of noval cyclohexane containing substituted thio piperazinium chloride [C6H11S(CH2)3C4H9N2C6H5Cl (L1Cl)]: Synthesis,crystal structure and supramolecularity of (L1NO3)

[C₆H₁₁S(CH₂)₃C₄H₉N₂C₆H₅Cl (L¹Cl)] has been synthesized by reaction of cyclohexyl thiol with 1-(chlorophenyl)-4-(3-chloropropyl) piperazine hydrochloride (P¹) under dry nitrogen atmosphere. The L¹Cl on reaction with Cd(NO₃)₂ forms a compound [L¹NO₃] having NHO hydrogen bonding. The single crystal structure of the compound L¹NO₃ is solved. The characteristic feature of these reactions is the retention of the piperazinium character from starting material (P¹) to ligand formation (L¹Cl) as well as in the formation of anion exchange product (L¹NO₃). L¹Cl and L¹NO₃ are characterized on the basis of physico-chemical and spectral (ESI Mass, FT-IR, ¹H, ¹³C and DEPT 135° ¹³C {¹H} NMR) studies. The proton and carbon-13 NMR spectra of L¹Cl and L¹NO₃ are characteristic. L¹NO₃ crystallizes in orthorhombic system with Pbca space group. Both piperazine and cyclohexane rings adopt the chair conformation with N₁, N₂ and C₁₄, C₁₇ out of plane. Geometry around quaternary nitrogen atom is distorted tetrahedral as revealed by the bond angles.     

Preparation of a new type of half-sandwich (alkoxylalkylcyclopentadienyl)titanium trichloride complex and X-ray structural characterization of (CH3OCH2CH(CH3)C5H4)TiCl3

New substituted alkoxylalkylcyclopentadienyl titanium trichloride complexes, CH₃OCH₂CH(CH₃)C₅H₄TiCl₃ (3), CH₃OCH(CH₃)CH₂C₅H₄TiCl₃ (4) and CH₃OCH₂CH₂CH₂C₅H₄TiCl₃ (5) have been synthesized and 3 has been studied by X-ray diffraction. The crystal structure of 3 shows that there is an intramolecular coordination between the ethereal oxygen atom in the side chain on the Cp ring and the titanium atom with an average Ti–O bond length of 2.24 Å. Due to steric limitation around the coordination sphere of titanium, the oxygen atoms in the side chain in complexes 4 and 5 do not coordinate with the central metals.     

DNA-Binding Study of Tetraaqua-bis(p-nitrobenzoato)cobalt(II) Dihydrate Complex: [Co(H2O)4(p-NO2C6H4COO)2]·2H2O

The interaction of [Co(H₂O)₄(p-NO₂C₆H₄COO)₂]^· 2H₂O with sheep genomic DNA has been investigated by spectroscopic studies and electrophoresis measurements. The interaction between cobalt(II) p-nitrobenzoate and DNA has been followed by gel electrophoresis while the concentration of the complex was increased from 0 to 14 mM. The spectroscopic study and electrophoretic experiments support the fact that the complex binds to DNA by intercalation via p-nitrobenzoate into the base pairs of DNA. The mobility of the bands decreased as the concentration of complex was increased, indicating that there was increase in interaction between the metal ion and DNA.     

Synthesis,spectroscopic and structural aspects of triphenylantimony(V) complex with internally functionalized acetylferroceneoxime: Crystal and molecular structures of [C5H5FeC5H4C(CH3)NO]2SbPh3 and C5H5FeC5H4C(CH3)NOH

Triorganoantimony(V) complex (C₅H₅FeC₅H₄C(CH₃)NO)₂SbPh₃ (1) has been prepared by the reaction of Ph₃SbCl₂ with acetylferroceneoxime C₅H₅FeC₅H₄C(CH₃)NOH (2) in 1:2 molar ratio in anhydrous toluene. The complexes have been characterized by elemental analyses, IR and NMR (¹H and ¹³C) spectroscopic studies, and biologic activity was measured. And crystal structures of 1, 2 were reported. The coordination geometry around the antimony atom in 1 was slightly distorted trigonal bipyramidal with the carbon atoms of the SbPh₃ unit in equatorial positions and the two oxygen atoms of the oxime group occupying axial positions. The free oxime was clearly hydrogen bonded (H–N 2.10 Å/2.04 Å in 2) to essentially form a dimer.     

Modeling interfacial tension of (CH4+N2)+H2O and (N2+CO2)+H2O systems using linear gradient theory

The linear gradient theory (LGT) of fluid interfaces in combination with the cubic-plus-association equation of state (CPA EOS) is applied to determine the interfacial tensions of (CH₄+N₂)+H₂O and (N₂+CO₂)+H₂O ternary mixtures from 298–373 K and 10–300 bar. First, the pure component influence parameters of CH₄, N₂, CO₂ and H₂O are obtained. Then, temperature-dependent expressions of binary interaction coefficient for (CH₄+H₂O), (N₂+H₂O) and (CO₂+H₂O) are correlated. These empirical correlations of pure component influence parameters and binary interaction coefficients are applied for ternary mixtures. For (CH₄+N₂)+H₂O and (N₂+CO₂)+H₂O mixtures, the predictions show good agreement with experimental data (overall AAD～1.31%).     

Trapping of CH3O formed from CO + H2

Methoxy formed on Al₂O₃ from¹³CO and H₂ coadsorption on Ni/Al₂O₃ was trapped by C₂H₅OH adsorption and temperature-programmed reaction (TPR). The presence of excess C₂H₅OH significantly increases the rate of¹³CH₃OH and (¹³CH₃)₂O formation. The¹³CH₃OH forms by the reaction of C₂H₅OH with¹³CH₃O on Al₂O₃. In the absence of C₂H₅OH,TPR following¹³CO and H₂ coadsorption did not produce significant amounts of¹³CH₃OHor(¹³CH₃)₂O.     

Reduction of n-C5H11N3 Catalyzed by [Mo2Fe6S8(OMe)3(SC6H4-p-n-C8H17)6]3– in an Aqueous Micellar Solution

Reduction of n-C₅H₁₁N₃ by Na₂S₂O₄ was performed in the presence of (n-Bu₄N)₃ [Mo₂Fe₆S₈(OMe)₃(SC₆H4-p-n-C₈H₁₇)₆] ((n-Bu₄N)₃ [Mo-Fe]) as a catalyst in aqueous Triton X-100 micellar solutions. The rate of the reduction is enhanced efficiently by the addition of methyl viologen (MV²⁺). The methyl viologen radical cation (MV⁺) produced by the reaction of MV²⁺ with Na₂S₂O₄ undergoes a disproportionation reaction to afford MV²⁺ and MV° in the micellar solution. The resultant MV° formed in the micelle transfers two electrons to [Mo-Fe]³⁻ effectively to give [Mo-Fe]⁵⁻, which reduces n-C₅H₁₁N₃ with two electrons to produce n-C₅H₁₁NH₂ and N₂.     

P[N(iBu)CH2CH2]3N: A versatile non-ionic base for the synthesis of higher coordinate silicates

A room temperature reaction of tetramethyl-orthosilicate with catechol or substituted catechol derivatives, or hydroxy carboxylic acids in the presence of the proazaphosphatrane P(ⁱBuNCH₂CH₂)₃N, readily affords the first examples of phosphonium salt stabilized higher coordinate silicates of the type [HP(ⁱBuNCH₂CH₂)₃N]₂[Si(L)₃] in high yields. A single crystal X-ray structural investigation of [HP(ⁱBuNCH₂CH₂)₃N]₂[Si(O₂C₆H₄)₃] revealed a hexacoordinate silicate framework with two independent phosphatranium cations, possessing strong transannular N_ax→P bonds.     

Hydrothermal synthesis,crystal structure and fluorescent properties of a novel 1D polymer: VO2(C7H3O4N)Ag(C10H8N2)·H2O

The hydrothermal synthesis of V₂O₅, AgNO₃, pyridine-2,6-dicarboxylic acid (H₂pdc) and 2,2′-bipyridine (bpy) in water at 160 °C for 4 days yields a novel 1D coordination polymer VO₂(C₇H₃O₄N)Ag(C₁₀H₈N₂)·H₂O (1). Each V center chelates to a tridentate ligand pdc^2? and coordinates to two O atoms, while the square based pyramid conformation of Ag center consists of three O atoms and a bpy molecular. V and Ag polyhedra alternate by either carboxyl or oxo bridges to further form a unique 3d–4d heterometal-based 1D double-chain ribbon.     

Über die Säuren HOOCCH(SX)CH(SX)COOH (X  CH2COOH,C6H5) und ihre Methylester

The Acids HOOCCH(SX)CH(SX)COOH (X  CH₂COOH, C₆H₅) and their Methyl Esters The acids HOOCCH(SX)CH(SX)COOH with X  CH₂COOH and C₆H₅ and their methyl esters have been prepared by addition of thiols to acetylene dicarboxylic acid as salt and methyl ester. The structures and configurations have been discussed.     

Synthesis,molecular, crystal and electronic structure of [RuCl2(PPh3)2(C3N2H4)2]

The reaction of [RuCl₂(PPh₃)₃] complex with pyrazole has been examined. A new ruthenium complex – [RuCl₂(PPh₃)₂(C₃N₂H₄)₂] has been obtained and characterised by IR and UV–Vis measurements. Crystal and molecular structure of the complex has been determined.