A Study on the Coking Sites ofγ-Alumina Surface Using 1-Methylnaphthalene as the Model Reactant

The support γ-Al_2O_3 was treated with 1-methylnaphthalene as the model reactant by respectively using the chemical static adsorption method and the accelerated coking method to study the coking sites of γ-Al_2O_3 surface. The carbon species formed on γ-Al_2O_3 surface were analyzed by CAT-CS, TG-MS, IR-OH, and Py-IR techniques. The results of characterization by CAT-CS and TG-MS techniques indicated that the carbon species formed during the chemical static adsorption process is mainly composed of the reversibly adsorbed coke precursors with a lowly-condensed state, while that formed after the accelerated coking process is probably related with the irreversibly adsorbed coke deposits with a highlycondensed state. The results of characterization by IR-OH and Py-IR techniques further implied that the formation of the two kinds of carbon species, i.e., coke precursors and coke deposits, are closely related with the basic hydroxyl groups and the strong Lewis acid sites on γ-Al_2O_3 surface. The results lead to a deep insight into the coking mechanism on the alumina surface.

Synthesis, Structure and Geometrical Calculation of a Novel Co-crystal of {[4-Bromo-2-(benzimidazol-2-yl)phenolato][2-(1-butylbenzimidazol-2-yl)phenolato]zinc(Ⅱ)] and Bis[μ-2-(1-butylbenzimidazol-2-yl)phenolato]-1κN^3:2κO;1κO:2κN^3-bis{[2-(1-butylbe

The title compound has been synthesized and characterized crystallographicaUy. It is a co-crystal consisting of two different neutral zinc（H） complexes with Hbpbm （Hbpbm = 4- bromo-2-（benzimidazol-2-yl）phenol） and Hnpbm （Hnpbm = 2-（1-butylbenzimidazol-2-yl）phenol）. One is a monomeric mixed-ligand complex of [Zn（bpbm）（npbm）] 1 and the other a dimer of [Zn2（npbm）4] 2 with their ratio of 2：1. Thus the overall formula for the title compound is 21.2. Adjacent 1 and 2 are connected to each other by intermolecular hydrogen bonding interactions in the lattice. The crystal data： monoclinic, space group P21/c, a = 15.0141（12）, b = 20.9941（17）, c = 18.4686（15） A, β = 97.445（2）°, V = 5772.4（8） A^3, Mr= 2429.68, Z = 2, Dc = 1.398 g/cm^3,μ = 1.579 -1 mm , F（000） = 2504, R = 0.0637 and wR = 0.1771 for 6464 observed reflections （I 〉 2σ（I））. The geometrical structure for 1 has also been theoretically optimized and compared with the experimental one.

Coupling reaction mechanism of 2-(2-bromo-4-fluorophenyl)-1-cyclohexen-1-yl trifluoromethane-sulfonate

The detailed mechanism of CuI-catalyzed C-O intramolecular coupling reaction of 2-(2-bromo-4-fluoro-phenyl)-1-cyclohexen-1-yl trifluoromethane–sulfonate was studied with the density functional theory(DFT). The geometries of the reactants,transition states, intermediates and products were optimized at the B3LYP/6-31+G* level. Meanwhile, the single point energy of species involved in gas and solvent at B3LYP/6-311+G* level was individually investigated. Polarizable continuum models(PCM)were applied to the dioxane and water solutions at the same level, respectively. Results show that the rate-limiting step, M3→TS3,does not change in different solutions. However, the activation energy in a dioxane solution is lower than that in water, which explains the previous experimental results. Compared with the non-catalyzed reaction process, the activation energy of the ratelimiting step is reduced by 56.53 kJ mol-1 in gas and 44.84 kJ mol 1in solvent, demonstrating a high catalytic efficiency of CuI.

Synthesis and Crystal Structure of 4-Bromo-5-ethoxy-3-methyl-5- (naphthalen-1-yl)-1-tosyl-1H-pyrrol-2(5H)-one

The title compound 4-bromo-5-ethoxy-3-methyl-5-（naphthalen-l-yl）-l-tosyl-lH- pyrrol-2（5H）-one 1 （C24H22BrNO4S, Mr = 500.40） has been synthesized and its crystal structure was determined by single-crystal X-ray diffraction analysis. It crystallizes in monoclinic, space group P21/n with a = 8.8562（15）, b = 18.118（3）, c = 14.055（2）A, β = 99.855（3）^o, V= 2221.9（6）A3, Z = 4, Dc = 1.496 g/cm^3,μ= 1.975 mm^-1, 2 = 0.71073A, F（000） = 1024, R = 0.0607 and wR = 0.1371.

Synthesis and Crystal Structure of N1-(2-(4-Bromo-2-nitrophenoxy)-2-dimethyl acyloxymethyl)-5-fluorouracil

The title compound N1-（2-（4-bromo-2-nitrophenoxy）-2-dimethyl acyloxymethyl）-5-fluorouracil（C15H13BrFN3O7, Mr = 446.19） was synthesized and structurally characterized by ^1H-NMR, -（13）C-NMR, ESI-MS and single-crystal X-ray diffraction. The compound crystallizes in triclinic, space group P1, with a = 8.3325（6）, b = 10.1808（13）, c = 11.8194（16） A, α = 73.194（12）, β= 72.351（9）, γ = 89.509（8）o, V = 911.2（2） A^3, Z = 2, T = 300.79（10） K, μ（Cu Kα） = 3.578 mm^-1, Dc = 1.626 g/cm3, F（000） = 448.0, GOF = 1.060, 5723 reflections measured（8.232≤2θ≤139.592°）, 3339 unique（Rint = 0.0184, Rsigma = 0.0254） which were used in all calculations. The final R = 0.0517（I 〉 2s（I）） and wR = 0.1494（all data）. Hydrogen bonds and π-π interactions together stabilize the structure of the molecule. The preliminary biological test shows that the title compound has good antitumor activity against A549 in vitro and lower toxicity to normal cells.

Synthesis and Structural Characterization of Organophosphorus Ylide-1-(3-nitrophenyl)-2-(triphenyl phosphoranylidene)ethanone

The title compound Ph3P=C（H）C（O）PhNO2 （L） has been prepared by the addition of triphenylphosphine in acetone as solvent to 2-bromo-1-（3,nitrophenyl）ethanone followed by the addition of alkaline solution of sodium hydroxide. The yellow crystals of the title ylide were grown in methanol/chloroform solution by drop method without stirring at room temperature. The solid state structure of ylide has been established by X-ray crystallography analysis. In the molecule of the title compound, the geometry around the P atom is nearly tetrahedral and the O atom is in synperiplanar orientation to the P atom. The nitrophenyl ring is twisted with respect to the plane of the carbonyl group through an angle of 36.6（1）°. The crystal （C26H20NO3P, Mr = 425.40） belongs to the monoclinic system, space group P21/n with a = 10.889（3）, b = 14.467（3）, e = 13.872（4）A, β = 103.08（3）°, V = 2128.6（10） A3, Z= 4, T= 100（2） K, R = 0.059 and wR = 0.163 for 3984 observed reflections with I〉 2σ（I）.

THE DNase-1 SENSITIVE REGIONS IN GENOMES OF BURKITT' S LYMPHOMA CELLS

This article reported the distribution of DNase-1 sensitive regions in genomes of three Burkitt's lymphoma cell lines, P3HR-1, Raji and Ramos cell lines using a new method of in situ nick translation of chromosomes substituted completely by BrdU. The results showed that the Blym locus on chromosomes In three cell lines and the c-myc locus on chromosomes in P3HR-1 were the DNase-1 sensitive regions and found that the rearrangemental sites of chromosomes present in three Burkltt' s lymphoma cell lines were sensitive to DNase-1 digestion, Indicating that c-myc, bcl-1 genes located at the rearrangemental sites and the Blym gene in Burkltt' s lymphoma are the active genes having the capability of expression.

Preconcentration/Separation of Some Metal Ions Using Sodium Dodecyl Sulfate Coated Alumina Modified with Bis（5-bromo- 2-hydroxy-benzaldehyde）-2-methyl-1,5-pentane Diimine （BBHBPDI） Prior to Their Flame-AAS Determination

Preconcentration/separation of Co（II）, Fe（III）, Pb（II）, Cr（IIl）, Cu（II） and Cd（II） ions using bis（5-bromo- 2-hydroxy-benzaldehyde）-2-methy1-1,5-pentane diimine （BBHBPDI） on SDS coated alumina has been reported. The influences of the analytical parameters including pH, ligand and SDS amount, type and concentration of eluent and sample volume on metal ions recoveries were investigated. At optimum values of all variables the relative standard deviation are between 2.5-2.7 and preconcentration factor was 375, while recoveries for all understudy metal ions are higher than 95%, determination limits are between 1.5-2.7. The method has been successfully applied to determination of Co（II）, Fe（III）, Pb（II）, Cr（III）, Cu（II） and Cd（II） ions content in some real samples.

Synthesis and Characterization of a Novel Cellulose Nonionic Ether

A kind of novel cellulose ether-trihydroxybutyl cellulose (THBC) was synthesized. The process includes the steam explosion treatment of cotton cellulose, alkalization, etherification and purification. Sweep electron microscope (SEM), Fourier transform infrared (FTIR) and X-ray diffraction were used to characterize the cellulose pretreated and the product. The effects of reaction conditions (temperature, time) on the molecular substitution (S_m) were discussed. To obtain a higher degree of molecular substitution, the reaction temperature is 80 ℃, and the reaction time is 4 h.

Unexpected BrdU inhibition on astrocyte-to-neuron conversion

5-Bromo-2′-deoxyuridine(BrdU)is a halogenated pyrimidine that can be incorporated into newly synthesized DNA during the S phase of the cell cycle.BrdU is widely used in fate-mapping studies of embryonic and adult neurogenesis to identify newborn neurons,however side effects on neural stem cells and their progeny have been reported.In vivo astrocyte-to-neuron(AtN)conversion is a new approach for generating newborn neurons by directly converting endogenous astrocytes into neurons.The BrdU-labeling strategy has been used to trace astrocyte-converted neurons,but whether BrdU has any effect on the AtN conversion is unknown.Here,while conducting a NeuroD1-mediated AtN conversion study using BrdU to label dividing reactive astrocytes following ischemic injury,we accidentally discovered that BrdU inhibited AtN conversion.We initially found a gradual reduction in BrdU-labeled astrocytes during NeuroD1-mediated AtN conversion in the mouse cortex.Although most NeuroD1-infected astrocytes were converted into neurons,the number of BrdU-labeled neurons was surprisingly low.To exclude the possibility that this BrdU inhibition was caused by the ischemic injury,we conducted an in vitro AtN conversion study by overexpressing NeuroD1 in cultured cortical astrocytes in the presence or absence of BrdU.Surprisingly,we also found a significantly lower conversion rate and a smaller number of converted neurons in the BrdU-treated group compared with the untreated group.These results revealed an unexpected inhibitory effect of BrdU on AtN conversion,suggesting more caution is needed when using BrdU in AtN conversion studies and in data interpretation.

A Total and Convenient Synthesis of Orixiarine

A simple total synthesis of the quinoline alkaloid, orixiarine was achieved from N-methylaniline and 1-bromo-3-methyl-2-butanone.

Competition of Aromatic Bromination and Nitration in Concentrated Sulfuric Acid

Composition of bromine and nitric acid in concentrated sulfuric acid is effective for bromination of strongly deactivated aromatic compounds and for nitration and bromination of moderately deactivated compounds in one stage. The question why brominating agent is more reactive than nitrating agent in relation to strongly deactivated aromatic compounds and is less reactive in relation to moderate deactivated ones is discussed.