在分散型催化剂下渣油中饱和分和芳香分临氢热反应行为的研

在微型高压釜中研究了克拉玛依常压渣油（KLAR）和辽河减压渣油（LHVR）的饱和分、芳香分在分散型催化剂作用下的临氢热反应行为并计算其动力学参数。结果表明，饱和分与芳香分主要发生裂化反应，生成石脑油与柴油馏分，不会生成甲苯不溶物，极少量的芳香分缩合生成沥青质。在相同的反应苛刻度下，KLAR与LHVR饱和分裂化和缩合产物产率没有明显的差别，而KLAR芳香分的裂化产物产率略高于LHVR芳香分，而其缩合产物产率略低于LHVR饱和分。     

Direct catalytic asymmetric aldol-Tishchenko reaction

A direct catalytic asymmetric aldol reaction of propionate equivalent was achieved via the aldol-Tishchenko reaction. Coupling an irreversible Tishchenko reaction to a reversible aldol reaction overcame the retro-aldol reaction problem and thereby afforded the products in high enantio and diastereoselectivity using 10 mol % of the asymmetric catalyst. A variety of ketones and aldehydes, including propyl and butyl ketones, were coupled efficiently, yielding the corresponding aldol-Tishchenko products in up to 96% yield and 95% ee. Diastereoselectivity was generally below the detection limit of 1H NMR (>98:2). Preliminary studies performed to clarify the mechanism revealed that the aldol products were racemic with no diastereoselectivity. On the other hand, the Tishchenko products were obtained in a highly enantiocontrolled manner.     

Reaction of hexadecafluorobicyclo[4.4.0]dec-1(6)-ene with diethylamine

The spectral characteristics of products formed in the reaction of an incompletely fluorinated impurity in perfluorodecalin, hexadecafluorobicyclo[4.4.0]dec-1(6)-ene, with amines in various solvents were studied. The reaction rates in various solvents were compared, and the distribution of the reaction products between perfluorodecalin and solvents was examined.     

氮化硅纳米线制备过程中反应条件的影响

采用X 射线衍射和扫描电子显微镜技术, 考察了溶胶-凝胶法制备氮化硅纳米线过程中反应条件(添加剂种类和含量、反应时间以及反应温度)对碳热还原产物组成和形貌的影响. 结果表明, 碳化后铁含量为5%(w)的凝胶, 在1300 ℃下反应10 h, Si₃N₄纳米线产率较高. 添加剂的种类和含量不同, 所得产物的组成和形貌也不相同.随着反应温度的升高或反应时间的延长,产物经历了一个从SiO_x到Si₂N₂O 再到Si₃N₄的转变过程. 在有金属组分存在时, Si₃N₄纳米线由气-液-固过程形成.     

N-β-羟乙基乙二胺在铜催化剂上的反应机理

1　前言哌嗪是一种重要的化工原料和医药中间体 ,应用十分广泛 [1] ,数十年来国内外对其合成工艺进行了大量的研究 ,其中以醇胺为原料在一定催化剂作用下脱水环合生成哌嗪的研究最为引人注目 [2～ 4 ]。我们研究开发了以 N-β-羟乙基乙二胺 (以下简称羟乙 )为原料 ,在铜催化剂作用下合成哌嗪的工艺。通过醇制备胺的反应是由 Sabatier和 Mail-he在 1 90 9年研究发现的 ,称为醇催化胺化反应[5] 。随后人们对于此类醇催化胺化反应的历程进行了大量的研究。Schwegler和 Adkins认为反应是一个脱氢 /加氢历程 [6 ] ,有机胺是通过烯胺(雪弗碱 )中…     

Analysis of reaction products of cocaine and hydrogen peroxide by high-performance liquid chromatography/mass spectrometry

The change of chemical structure of cocaine in the presence of hydrogen peroxide, a main component of hair dye and decolorant treatments, was studied. High-performance liquid chromatography/mass spectrometry (LC/MS) was used for the separation and identification of cocaine derivatives. After a mixture of cocaine and hydrogen peroxide solutions was incubated at 39 degrees C (this temperature is commonly used when the hair is treated with hair dye or decolorant) for 24 h, six reaction products were detected by LC/MS. Two of them were ecgonine methyl ester and benzoylecgonine, which are metabolites of cocaine. The other reaction products were assumed to be ortho-, meta- and para-hydroxycocaines and dihydroxycocaine, in each of which the benzene ring was hydroxylated by the reaction. These five reaction products (except for dihydroxycocaine) were found immediately after mixing cocaine and hydrogen peroxide. Therefore, the above reaction products might be present in the hair of cocaine users that had treated their hair with hair dye or decolorant.     

Mo-V-Nb多组元氧化物催化乳酸氧化脱氢反应制备丙酮酸

丙酮酸是一种重要的有机合成和药物合成中间体,本文采用成本低廉的乳酸为原料,以Mo-V-Nb多组元氧化物为催化剂,在较低的反应温度下催化氧化脱氢合成了具有高附加值的丙酮酸。应用X射线衍射（XRD）和扫描电子显微镜（SEM）表征了Mo-V-Nb多组元氧化物的物相组成和微观结构,采用气相色谱质谱联用（GC-MS）分析了反应产物,研究了乳酸氧化脱氢可能的反应路径,并深入探讨了关键反应参数反应温度、氧气分压和质量空速对催化选择性和乳酸转化率的影响。     

亲电反应中的缺电子中心

对于不饱和烃类化合物的亲电反应,在反应类型上,有亲电加成和亲电取代;在反应产物上,有取代产物和加成产物,而且在加成产物中既有马氏加成、又有反马氏加成产物。知识点多而且复杂,学生学习记忆往往比较困难。本文以缺电子中心为主线,系统分析了亲电反应中的4种主要缺电子中心(包括正离子、自由基、卡宾和中性分子),从其结构特点和反应机理归纳总结了各种反应底物的亲电反应,以期对亲电反应有一个更深入、系统的认识。     

Effect of a proximal substituent on the triruthenium dodecacarbonyl-catalyzed reductive carbonylation of nitroarenes

Three nitroarenes were submitted to Ru₃(CO)₁₂-catalyzed reductive carbonylation in acetonitrile and in cis-cyclooctene. The main reaction products were the corresponding amines, ureas and six- or five-membered cyclization products. Optimization of the reaction varying the temperature, the CO pressure, the catalyst/substrate ratio and the reaction time and a statistical analysis of conversion and selectivity data allow to suggest a reaction mechanism in some reaction conditions.     

Tethered aminohydroxylation using acyclic homo-allylic sulfamate esters and sulfonamides as substrates

Homo-allylic sulfamate esters and sulfonamides are shown to be useful substrates for the tethered aminohydroxylation (TA) reaction. The sulfamate esters undergo the TA reaction delivering 1,2,3-oxathiazinane products whereas the sulfonamides give 1,2-thiazinane products. A range of acyclic homo-allylic sulfamate esters were prepared and subjected to the TA reaction to establish the scope of the process. Nucleophilic ring-opening reactions of the 1,2,3-oxathiazinane products are also described.     

Mo-V-Nb多组元氧化物催化乳酸氧化脱氢反应制备丙酮酸

丙酮酸是一种重要的有机合成和药物合成中间体,本文采用成本低廉的乳酸为原料,以Mo-V-Nb多组元氧化物为催化剂,在较低的反应温度下催化氧化脱氢合成了具有高附加值的丙酮酸。应用X射线衍射(XRD)和扫描电子显微镜(SEM)表征了Mo-V-Nb多组元氧化物的物相组成和微观结构,采用气相色谱质谱联用(GC-MS)分析了反应产物,研究了乳酸氧化脱氢可能的反应路径,并深入探讨了关键反应参数反应温度、氧气分压和质量空速对催化选择性和乳酸转化率的影响。     

Fine synthetic nucleoside chemistry based on nucleoside natural products synthesis

Synthetic nucleoside chemistry based on nucleoside natural products synthesis were described. First, a samarium diiodide (SmI 2)-promoted aldol reaction with the use of alpha-phenylthioketone as an enolate was developed. The characteristics of this reaction are that the enolate can be regioselectively generated and the aldol reaction proceeds under near neutral condition. This reaction is proved to be a powerful reaction for the synthesis of complex nucleoside natural products, and herbicidin B and fully protected tunicaminyluracil, which were undecose nucleoside natural products, were synthesized. Next, the synthetic methodology of the caprazamycins, which are promising antibacterial nucleoside natural products, was also developed by the strategy including beta-selective ribosylation without using a neighboring group participation. Our synthetic route provided a range of key analogues with partial structures to define the pharmacophore. Simplification of the caprazamycins was further pursued to develop diketopiperazine analogs.     

ToF‐SIMS characterization of glyoxal surface oxidation products by hydrogen peroxide: A comparison between dry and liquid samples

As one of the simplest volatile organic compounds, glyoxal and its oxidation products were considered to be important precursors to aqueous secondary organic aerosol formation. Herein, we analyzed products from glyoxal oxidation by hydrogen peroxide in dry and liquid samples using time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). ToF‐SIMS spectra and spectral principal component analysis (PCA) were used to investigate surface oxidation products. Dry samples were prepared on clean silicon wafers. Liquid samples consisting of glyoxal and hydrogen peroxide (H₂O₂) were introduced to a vacuum compatible microfluidic reactor prior to UV illumination or dark aging followed by in situ liquid SIMS analysis. A number of reaction products were observed in both dry and liquid samples; different oligomers and carboxylic acids could be formed depending on reaction conditions. In addition, hydrolyzed products were observed in the liquid samples, but not in the dry samples. Although dry samples reveal some products of the aqueous process, they are not fully representative as results from those of the aqueous samples. Our findings suggest that the ability to characterize the liquid surface reaction products provides more realistic information of the reaction products associated with aqueous secondary organic aerosol formation in the atmosphere. Meanwhile, the high mass resolution spectra from the dry sample SIMS measurement are helpful to identify oxidation products in the liquid samples.     

Mild benzene-thermal route to GaP nanorods and nanospheres

GaP nanorods and nanospheres were synthesized from a mild benzene-thermal route at 240 and 300 degrees C, respectively, using Na, P, and GaCl(3) as the starting materials. The structure of the products was identified as zinc blende phase by X-ray powder diffraction (XRD). Transmission electron microscopy (TEM) images showed that, when the reaction temperature was 240 degrees C, the products were nanorods with widths of 20-40 nm and lengths of 200-500 nm and nanospheres with diameters of 20-40 nm. However, when the reaction temperature was increased to 300 degrees C, the products were only nanospheres, and the diameters increased to 40-60 nm. The reaction proceeded through a metallic gallium intermediate, and a solution-liquid-solid (SLS) mechanism was proposed for the one-dimensional growth. The products were also investigated by UV-vis absorption and X-ray photoelectron spectroscopy.     

无溶剂下位阻控制的Biginelli反应

在NaHSO4作催化剂, 无溶剂下将水杨醛、活泼亚甲基化合物和尿素或硫脲进行Biginelli 反应, 高收率地合成了一系列monastrol类物质. 产物的结构通过IR, 1H NMR, 13C NMR光谱数据和单晶解析表征和确定. 对于不同活泼亚甲基化合物参与的反应, 形成了4-(2-羟基苯基)嘧啶衍生物2和氧桥嘧啶衍生物3两类物质, 活泼亚甲基化合物分子中醇酯基的结构是决定两种嘧啶衍生物结构的主要因素. 对于以前报道的Biginelli产物4-(2-羟基苯基)嘧啶衍生物2a和氧桥嘧啶衍生物3e的形成也进行了讨论.     

Analysis of oligomeric and monomeric carbohydrates from hydrothermal degradation of cotton-waste materials using HPLC and GPC

Summary The hydrolysis of different cotton materials under hydrothermal conditions was investigated. For the analysis of the resulting reaction products high-performance liquid chromatography and gel-permeation chromatography were applied. HPLC columns with ion exchange materials as stationary phases (HPX 87P and Shodex S801) enabled the separation of monomeric sugars and degradation products. Oligomeric sugars were analyzed using a gel column (Bio-Gel P-2) as well as a HPLC column (HPX 42A). Through identification of additional reaction products the mass balance of the hydrolysis can be improved and the analysis of the distribution of the oligomeric sugars gives information for the selection of the reaction conditions.     

Amino-β-lactams in Ugi reaction: An efficient method for preparation of functionalized peptidomimetics

A synthetic strategy for the Ugi reaction on amino-β-lactam synthon 1 was developed. The Ugi reaction products 5 were obtained in satisfactory yields (47–78%) and generally, low diastereoselectivity (up to 72:28 dr). In case of Ugi products 5 derived from cyclohexylcarbaldehyde and amino-β-lactam 1, the reaction yields were lower (38–61%) but the products were obtained in high diastereoselectivity (>95:5).     

Mechanistic studies of hydrogen-peroxide-mediated anthocyanin oxidation

The oxidation of cyanidin-3-O-glucoside by hydrogen peroxide was investigated in a range of solvents. The reaction products had chemical structures identical to those formed by the reaction of this compound with the alkylperoxyl radical 2,2?-azobis(2,4-dimethyl)valeronitrile. A plausible oxidation mechanism was proposed based on the obtained reaction products, and this mechanism was confirmed by HPLC–MS experiments using ¹⁸O-labeled reagents. Further, the reaction conditions were found to influence both the reaction rate and the products formed during the transformation, which validated the proposed mechanism.     

二甲基烯丙基胺/溴代烷烃系列季铵盐的合成与表征

以溴代烷与二甲基烯丙基胺(DMAA)为原料合成了二甲基烯丙基类季铵盐;探讨了反应温度、原料配比、反应时间及溶剂对反应产率的影响,确定了最佳合成条件;并采用红外光谱仪、核磁共振谱仪(1 H NMR)及质谱仪表征了产物的结构.     

Depolymerization of Poly（bisphenol A carbonate） in Subcritical and Supercritical Toluene

The depolymerization of poly(bisphenol A carbonate)(PC) in subcritical and supercritical toluene was studied. The experimental parameters, which influence the depolymerization reaction such as temperature (570-633 K), pressure (4.0-7.0 MPa), reaction time (5-60 min), and toluene to PC weight ratio (3.0-11.0), were investigated, and the reaction products were determined by GC, GC/MS and FT-IR spectrometer. It was found that the main product of the depolymerization reaction was bisphenol A(BPA). BPA accounted for over 55.7% of the depolymerization products at reaction temperature 613 K, pressure 5.0-6.0 MPa, reaction time 15 min and toluene/PC weight ratio of around 7.0.