Cu-Ni-Zn三元脂肪醇胺化催化剂的研究

 长链烷基二甲基叔胺是一类重要的有机中间体,目前其主要的制备工艺是由脂肪醇和二甲胺在脱氢－加氢类催化剂的作用下进行胺化反应．改进脂肪醇胺化催化剂的主要目标是提高其选择性．对以Cu和Ni为活性组分,以碳酸钙为载体的催化剂体系中加入Zn助催化剂组分对催化剂选择性的影响进行了研究．结果发现,在相同Cu／Ni比的条件下,Zn在Cu－Ni催化剂体系中的一个主要作用是能够阻碍氧化态镍的还原,而催化剂的选择性与催化剂中镍的还原程度密切相关．     

Synthesis of 5-(1H-benzimidazol-2-yl)-1H-pyrazolo-[3,4-<Emphasis Type="Italic">b</Emphasis>]pyridines by the <Emphasis Type="Italic">p</Emphasis>-(dimethylamino)benzaldehyde modification of Hantzsch reaction

The reactions of p-(dimethylamino)benzaldehyde with 5-amino-3-methyl-1-phenylpyrazole and 2-RCOCH₂-1H-benzimidazoles have produced 5-(1H-benzimidazol-2-yl)-1H-pyrazolo[3,4-b]pyridines. The transformation includes the formation of compounds in accordance with a Hantzsch reaction containing a 1,4-dihydropyridine ring, and is completed by the aromatization either by the splitting off of N,N-dimethylanyline or oxidation. The splitting is produced by acetic acid and the oxidation by a nitrocompound. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 578–584, April 2007.     

Polyethyleneimine Methylenephosphonic Acid for the Solid-Phase Sorption of Lead(II)

Abstract

In the first part of this work, polyethyleneimine methylenephosphonic acid (PEIMPA) was used as an effective sorbent for solid-phase extraction of Pb(II) ions from an aqueous solution. Conditions for effective sorption are optimized with respect to different experimental parameters in a batch process. The results showed that the amount of extraction decreases with solution pH in the range between 3.5 and 5.8. The sorption capacity is 609 mg·g^?1. The second part of the study focuses on the recovery of Pb(II) from a synthesized binary solution of Pb(II)–Zn(II) and from real Zn(II)-electrolyzed wastewaters. The presence of Cd(II), Co(II), Cu(II), Fe(III), Ni(II), and Zn(II) in large concentrations has a significantly negative effect on extraction properties.     

Synthesis, π‐Face‐Selective Aggregation,and π‐Face Chiral Recognition of Configurationally Stable C3‐Symmetric Propeller‐Chiral Molecules with a π‐Core

The C₃‐symmetric propeller‐chiral compounds (P,P,P)‐ 1 and (M,M,M)‐ 1 with planar π‐cores perpendicular to the C₃‐axis were synthesized in optically pure states. (P,P,P)‐ 1 possesses two distinguishable propeller‐chiral π‐faces with rims of different heights named the (P/L)‐face and (P/H)‐face. Each face is configurationally stable because of the rigid structure of the helicenes contained in the π‐core. (P,P,P)‐ 1 formed dimeric aggregates in organic solutions as indicated by the results of ¹H NMR, CD, and UV/Vis spectroscopy and vapor pressure osmometry analyses. The (P/L)/(P/L) interactions were observed in the solid state by single‐crystal X‐ray analysis, and they were also predominant over the (P/H)/(P/H) and (P/L)/(P/H) interactions in solution, as indicated by the results of ¹H and 2D NMR spectroscopy analyses. The dimerization constant was obtained for a racemic mixture, which showed that the heterochiral (P,P,P)‐ 1 /(M,M,M)‐ 1 interactions were much weaker than the homochiral (P,P,P)‐ 1 /(P,P,P)‐ 1 interactions. The results indicated that the propeller‐chiral (P/L)‐face interacts with the (P/L)‐face more strongly than with the (P/H)‐face, (M/L)‐face, and (M/H)‐face. The study showed the π‐face‐selective aggregation and π‐face chiral recognition of the configurationally stable propeller‐chiral molecules.     

Polymer‐Coated PtCo Nanoparticles Deposited on Diblock Copolymer Templates: Chemical Selectivity versus Topographical Effects

Metal–polymer hybrid films are prepared by deposition of polymer‐coated PtCo nanoparticles onto block copolymer templates. For templating, a thin film of the lamella‐forming diblock copolymer poly(styrene‐b‐methyl methacrylate) P(S‐b‐MMA) is chemically etched and a topographical surface relief with 3 nm height difference is created. Two types of polymer‐grafted PtCo nanoparticles are compared to explore the impact of chemical selectivity versus the topographical effect of the nanotemplate. A preferable wetting of the polystyrene (PS) domains with poly(styrenesulfonate) (PSS)‐coated PtCo nanoparticles (instead of residing in the space between the domains) is observed. Our investigation reveals that the interaction between PSS‐coated nanoparticles and PS domains dominates over the topographical effects of the polymer surface. In contrast, a non‐selective deposition of poly(N‐vinyl‐2‐pyrrolidone) (PVP)‐coated PtCo nanoparticles and the formation of large metal‐particle aggregates on the film is observed.     

Synthesis and applications of a chiral-oxygenated 3-chloro-3,6-dihydro-2H-pyran obtained under Overman rearrangement conditions

A chlorinated side product was formed under Overman rearrangement conditions from a trichloroacetimidate along with the expected allylic amide. The chlorinated product derived from a hex-2-enopyranoside was obtained in a totally stereoselective manner, and it can be a useful synthetic intermediate for chlorinated sugars. In order to improve the isolated yields of either the expected Overman rearrangement product or the chlorinated compound, we carried out a thorough study on the experimental conditions. The application of the latter for the synthesis of potential calpain inhibitors is also reported.     

Comprehensive comparison of liquid chromatography selectivity as provided by two types of liquid chromatography detectors (high resolution mass spectrometry and tandem mass spectrometry): “Where is the crossover point?”

The selectivity of mass traces obtained by monitoring liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was compared. A number of blank extracts (fish, pork kidney, pork liver and honey) were separated by ultra performance liquid chromatography (UPLC). Detected were some 100 dummy transitions respectively dummy exact masses (traces). These dummy masses were the product of a random generator. The range of the permitted masses corresponded to those which are typical for analytes (e.g. veterinary drugs). The large number of monitored dummy traces ensured that endogenous compounds present in the matrix extract, produced a significant number of detectable chromatographic peaks. All obtained chromatographic peaks were integrated and standardized. Standardisation was done by dividing these absolute peak areas by the average response of a set of 7 different veterinary drugs. This permitted a direct comparison between the LC-HRMS and LC-MS/MS data. The data indicated that the selectivity of LC-HRMS exceeds LC-MS/MS, if high resolution mass spectrometry (HRMS) data is recorded with a resolution of 50,000 full width at half maximum (FWHM) and a corresponding mass window. This conclusion was further supported by experimental data (MS/MS based trace analysis), where a false positive finding was observed. An endogenous matrix compound present in honey matrix behaved like a banned nitroimidazole drug. This included identical retention time and two MRM traces, producing an MRM ratio between them, which perfectly matched the ratio observed in the external standard. HRMS measurement clearly resolved the interfering matrix compound and unmasked the false positive MS/MS finding.     

AT‐Specific DNA Binding of Binuclear Ruthenium Complexes at the Border of Threading Intercalation

The binuclear ruthenium complex [μ‐bidppz(phen)₄Ru₂]⁴⁺ has been extensively studied since the discovery of its unusual threading intercalation interaction with DNA, a binding mode with extremely slow binding and dissociation kinetics. The complex has been shown to be selective towards long stretches of alternating AT base pairs, which makes it interesting, for example, as a model compound for anti‐malaria drugs due to the high AT content of the genome of the malaria parasite P. falciparum. We have investigated the effect of bridging ligand structure on threading intercalation ability and found that length and rigidity as well as the size of the intercalated ring system are all factors that affect the rate and selectivity of the threading intercalation. In particular, we discovered a new DNA‐threading compound, [μ‐dppzip(phen)₄Ru₂]⁴⁺, which appears to be just at the border of being capable of threading intercalation and displays even greater selectivity for AT‐DNA than the parent compound, [μ‐bidppz(phen)₄Ru₂]⁴⁺.     

Mode Specificity,Bond Selectivity,and Product Energy Disposal in X + CH4/CHD3 (X=H,F, O(3P), Cl,and OH) Hydrogen Abstraction Reactions: Perspective from Sudden Vector Projection Model

Reactions between methane and various radicals have become the workhorse in our understanding of mode specificity and bond selectivity in bimolecular reactions. In this work, the recently proposed Sudden Vector Projection (SVP) model is used to gain insight into the existing experimental and theoretical data on these reactions. The SVP model attributes mode specificity and bond selectivity to the coupling of reactant modes/bonds with the reaction coordinate at the transition state. In the sudden limit, the strength of the coupling can be simply computed by projecting the corresponding reactant normal mode vector onto that of the imaginary frequency mode at the saddle point. In addition, the SVP model can be used to predict energy disposal in the products, thanks to microscopic reversibility. It is shown that most of the mode‐specific and bond‐selective chemistry in X + CH₄/CHD₃ (X=H, F, O(³P), Cl, and OH) reactions can be reasonably understood with this simple model.     

The Direct Electrochemical Oxidation of Ammonia in Propylene Carbonate: A Generic Approach to Amperometric Gas Sensors

The direct electrochemical oxidation of ammonia in propylene carbonate is reported for the first time. The voltammetric responses at glassy carbon, boron‐doped diamond, edge and basal plane pyrolytic graphite electrodes are explored and compared with the outcome indicating that the optimum electrode substrate for analytical purposes in this solvent is glassy carbon. Proof‐of‐concept is shown for the amperometric detection of ammonia using basal plane pyrolytic graphite electrodes abrasively modified with glassy carbon spheres. Given the significantly lower vapor pressure of propylene carbonate in comparison to water the implications for extending the life‐time of practical sensors are evident. Propylene carbonate shows a wide potential window with glassy carbon electrodes permitting this approach to be used for a potential diversity of gaseous analytes.