脂肪酸加氢改性Ni及Ni-Pd催化剂的制备

工业动植物油脚的主要成分为不饱和脂肪酸,通过催化加氢制得的硬脂酸[1,2],可作橡胶添加剂。但不饱和脂肪酸的酸值较高,易使镍催化剂皂化中毒而失活。本文在镍催化剂的基础上,加入微量的过渡或碱士等活泼金属作助剂,提高催化剂的抗皂化性能;加入微量钯,提高催化剂的活性,采用沉淀法,以硅藻土为载体,制备了负载型改性Ni及Ni Pd催化剂。并与国内化工企业常用的棕榈酸(酸值为188 6mgKOH/g)进口加氢催化剂USA 140和USA 110在相同条件下对进行对比。1　实验部分1 1　催化剂制备将18gNi(NO3)2:6H2O溶于130ml水,再依次加入一定配比的过…     

STUDY ON PREPARATION OF INORGANIC COMPOSITE MEMBRANE AND ITS PROPERTIES FOR HYDROGEN PERMEATION

IntroductionDevclopmcntoftcchniqucsforthcscparationofgascousmixturesisofgrcatimportancetochemicalindustries.Rccentadvanccsinceramicmaterialprocessinghavcstimulatedtheeffortstodcvclopccramicormctallicmcmbrancsforgasseparation.Suchmembraneswouldbesuitableforthescparationsathightemperatureatx`hichthcx`ellcstablishedorganicpol}mermcmbranescannotfunctionButmostcommercialceramicmembranesxvhichcanbcobtainedinmarkctaremicroporous(porediamcterfromO.ItoloPm)whereseparationmcchanismisgovcrncdbyKnudscnd…     

β—型过渡元素三取代钨锗杂多配合物的合成,表征和催化活性

报道Ａ－β－Ｍ＇ｘＨｙ－［ＧｅＷＯＭ３（Ｈ２Ｏ）３Ｏ３７］．ｎＨ２Ｏ（Ｍ＝Ｃｒ＾３＾＋，Ｃｏ＾２＾＋，Ｎｉ＾２＾＋，Ｃｕ＾２＾＋；Ｍ＇＝Ｂｕ４Ｎ＾＋，Ｋ＾＋）的立体有择合成法制备及红外和远红外光谱，紫外和可见光谱和循环伏安，磁化率和磁矩，ＸＰＳ，ＥＳＲ以及催化活性等研究结果。     

Über die Darstellung von Di(i-propyl)thiosulfonium-Salzen

On the Preparation of Di(i-propyl)thiosulfonium Salts [1] The preparation of the mercaptosulfonium salts (i-C₃H₇)₂SSX⁺SbCl₆^? (X = H, D) and of the chlorothiosulfonium salts (i-C₃H₇)₂SSCl⁺MF₆^? (M = As, Sb) and (i-C₃H₇)₂SSSCl⁺SbCl₆^? is reported. They are formed by reaction of chlorinated or protonated (i-C₃H₇)₂S with excess H₂S or SCl₂ and S₂Cl₂. The thiosulfonium compounds are characterized by vibrational and NMR spectroscopic methods.     

Ga8Ir4B – ein Gallium-Iridiumborid mit isolierten,annähernd quadratisch planaren Ir4B-Gruppen in einer vom CaF2-Typ abgeleiteten Struktur

Ga₈Ir₄B – a Gallium Iridium Boride with isolated, nearly square planar Ir₄B Groups in a Structure derived from the CaF₂ Type The new compound Ga₈Ir₄B (tetragonal, I4₁/acd, a = 853.69(2) pm, c = 2 105.69(6) pm, Z = 8, 614 reflections, 31 parameters, R = 0.034) was prepared by reaction of the elements at 1 100°C. The structure is derived from the CaF₂ type. It contains isolated Ir₄B groups with boron in an unusual, nearly square planar coordination.     

Darstellung, 19F-NMR-spektroskopischer Nachweis und Untersuchung zur Bildung der metallgemischten Clusteranionen [(Mo6−nWnCl)F]2−, n = 0−6

Preparation, ¹⁹F NMR Spectroscopic Evidence and Study of the Formation of Metal-Mixed Cluster Anions [(Mo_6?nW_nCl )F ]^2?, n = 0?6 The complete system of metal-mixed octahedral cluster ions [(Mo_6?nW_nCl)F]^2?, n = 0?6, is prepared by tempering Mo powder with WCl₆ at 600°C. A mixture containing inclusively the geometric isomers (n = 2, 3, 4) all ten possible species is transferred into the tetra-n-butylammonium salts (TBA)₂[(Mo_6?nW_nCl)F]. In the ¹⁹F nmr spectrum the 24 expected signals are observed, assigned on the basis of their chemical shifts, multiplicities and intensities, and confirmed by a 2D-¹⁹F-¹⁹F COSY spectrum. From the integrated intensities the distribution of the different components is derived revealing a non-statistical formation, in that isomers with Mo…?Mo or W…?W atoms in trans-positions in comparision to those with mixed Mo…?W axes are favoured, and that especially the homoleptic compounds Mo₆ and W₆ are present to an over-average extent. Evaluation of ¹⁹F chemical shifts reveals that F bound to W which is in antipodal position to Mo resonates at higher field compared to F bound to W in a W…?W arrangement, caused by an increased shielding, which is synonymous to a positive antipodal-effect by Mo. Vice versa F bound to Mo with an antipodal W resonates at lower field compared with F bound to Mo in an Mo…?Mo arrangement caused by an increased deshielding and synonymous a negative antipodal-effect by W. The chemical shifts, resulting from antipodal-effects, are different for the compounds within the [(Mo_6?nW_nCl)F]^2? - system. The difference of the antipodal effect of successive substitution products results in characteristic values designated as antipodal shift constants, depending on the kind of substituents, which is valid for other cluster systems, too.     

Automated determination of verapamil and norverapamil in human plasma with on-line coupling of dialysis to high-performance liquid chromatography and fluorometric detection

A fully automated method for the simultaneous determination of verapamil and its main metabolite norverapamil in human plasma is described. This method is based on on-line sample preparation using dialysis followed by clean-up and enrichment of the dialysate on a precolumn and subsequent HPLC analysis with fluorometric detection. All sample handling operations were performed automatically by a sample processor equipped with a robotic arm (ASTED system). The plasma samples were dialysed on a cellulose acetate membrane (cut-off: 15 kD) and the dialysate was purified and enriched on a short pre-column filled with cyanopropyl silica. Before starting dialysis, this trace enrichment column (TEC) was first conditioned with the HPLC mobile phase and then with pH 3.0 acetate buffer. 370 μl of plasma sample spiked with the internal standard (gallopamil) were dialysed in the static-pulsed mode. The solution at the donor side was pH 3.0 acetate buffer containing Triton X-100 while the acceptor solution was made of the same acetate buffer. When dialysis was discontinued, the analytes were desorbed from the TEC by the HPLC mobile phase and transferred to the C₁₈ analytical column by means of a switching valve. This mobile phase consisted of a mixture of acetonitrile, pH 3.0 acetate buffer and 2-aminoheptane. The influence of different parameters of the dialysis process on the recovery of verapamil and norverapamil has been studied. The effect of the volume, the aspirating and dispensing flow-rates of the dialysis solution has been investigated. The recoveries of verapamil and norverapamil in plasma were close to 75% and the limits of quantification were 5 ng/ml for both analytes. The method was found to be linear in the concentration range from 5 to 500 ng/ml (r²: 0.9996 for both analytes). The intra-day and inter-day reproducibilities at a concentration of 100 ng/ml were 2.3% and 5.6% for verapamil and 1.7% and 5.1% for norverapamil, respectively.     

Synthesis and Structure of the Centered Cluster Compound Ba3(Zr6Cl18Be)

Reaction of powdered Zr with ZrCl₄, BaCl₂ and Be in suitable proportions in a Ta container at 800°C produces the title compound. Suitable monocrystals for X-ray diffraction were obtained from reactions to which a comparable amount of Hg₂Cl₂ had been added. The structure of Ba₃Zr₆Cl₁₈Be is a superstructure of the K₂ZrCl₆ · Zr₆Cl₁₈H type (R3 c, Z = 6; a = 9.6852 (9) Å, c = 52.52 (1) Å; R, R_w = 2.7, 3.2% for 826 independent reflections, 2θ ≤ 50°). Trigonally compressed [Zr₆(Be)Cl₁₂ⁱ]Cl₆^a clusters are interconnected by six-coordinate barium atoms that lie in Cl^a antiprisms (a twisted version of the Zr^IV site) while (9 + 3)-coordinate barium substitutes for potassium within chlorine layers. Distortions associated with the size and field of barium are responsible for the superstructure and for differences from other analogues.     

Synthesis,crystal structure,magnetism, and absorption spectra of A2UX5 Type Halides (A = K,Rb; X = Cl,Br, I)

The ternary uranium(III) halides A₂UX₅ (A = K, Rb; X = Cl, Br, I) have been prepared from the binary components AX and UX₃ in sealed tantalum containers. According to their Guinier X-ray powder patterns, they all crystallize with the K₂PrCl₅/Y₂HfS₅ type of structure. Lattice constants for ambient temperature are reported. Single-crystal structure refinemens were undertaken for K₂UI₅ and Rb₂UCl₅. Magnetic susceptibility data were recorded with a SQUID magnetometer from liquid helium to room temperature. One-dimensional (intrachain) and three-dimensional antiferromagnetic ordering occur at low temperatures dependent upon the U³⁺? U³⁺ distance. Absorption spectra were recorded between 4 000 and 28 000 cm^?1. They show f—f transitions typical for U³⁺ and, depending on the halide, very strong f—d transitions above 14 000 to 15 000 cm^?1, respectively.     

Biocatalytic synthesis of polymers. III. Formation of a high molecular weight polyester through limitation of hydrolysis by enzyme-bound water and through equilibrium control

Enzyme-catalyzed preparation of polymers offers several potentially valuable advantages over the usual polymerization procedures and has been studied for several years. A significant limitation on the polyesters prepared to date has been the low molecular weights achieved. The present studies have established that, in the polycondensation of bis(2,2,2-trifluoroethyl) glutarate with 1,4-butanediol using porcine pancreatic lipase as the catalyst, this limitation arises from at least two sources: hydrolysis of activated ester end groups by water introduced along with the enzyme and the polymerization's reaching equilibrium despite using the poorly nucleophilic 2,2,2-trifluoroethanol as the leaving group. Evidence is also developed that the presence of trifluoroethanol accelerates the release of the enzyme-bound water which hydrolyzes the activated ester end groups. The hydrolysis could be avoided by choosing a relatively high-boiling solvent, such as bis(2-ethoxyethyl) ether, then removing the trifluoroethanol by placing the reaction mixture under vacuum periodically or by drying the enzyme rigorously. The vacuum method also removed the limitation on molecular weight resulting from the reaction's reaching equilibrium. A further improvement in the molecular weight to nearly 40,000 daltons, well within the range that is technically interesting, was achieved by using 1,2-dimethoxybenzene or 1,3-dimethoxybenzene as the polymerization solvent. © 1995 John Wiley & Sons, Inc.