Ceric（Ⅳ）-mediated Oxidative Addition of 1, 3-Dicarbonyl Compounds to MCPs： A Facile Access to Dihydrofuran Derivatives Incorporating Cyclopropyl Groups

Alkylidenecyclopropanes undergo ceric（Ⅳ） ammonium nitrate （CAN）-mediated addition reaction with 1,3-dicarbonyl compounds leading to dihydrofuran derivatives incorporating cyclopropyl groups in moderate yields.     

两种薄层色谱直接拆分美托洛尔的方法研究

β-受体阻断药物美托洛尔有两个对映异构体,其药理学、毒理学及药代动力学具有极大的差异。研究建立了以D-10樟脑磺酸铵作为流动相手性离子对添加剂拆分美托洛尔对映体的薄层色谱方法,其最佳色谱条件为:D-10-樟脑磺酸铵溶液(0.17mmol/L,pH7.5)/二氯甲烷/甲醇(0.3/2.06/0.64,V/V/V),室温(15℃)下预饱和30m in,样品pH为8.0;研究建立了以β-环糊精固载薄层色谱拆分美托洛尔的方法,最佳色谱条件为:按硅胶GF254∶β-环糊精质量为30∶1的比例铺板,甲醇/二氯甲烷(0.87/2.13,V/V),室温(17℃)。两种方法均具有操作简便、经济、重现性好、结果可靠的特点。     

三磷酸腺苷生物发光法快速测定食品中细菌的含量

建立了测定食品中细菌三磷酸腺苷(ATP)的生物发光分析方法.生物发光原理基于萤光素酶、虫萤光素、氧气、ATP和Mg2+的催化氧化反应.产生的光信号强度与ATP含量成一定关系.考察了各种物理化学参数对反应的影响.反应体系最优化条件:pH 7.4、牛血清白蛋白(BSA)浓度为1.0 g/L和室温反应.方法检出限为1.0×10-12mol/L,线性范围1.0×10-9～1.0×10-11mol/L,分析时间30 min,批内变异和批间变异分别小于4%和5%.研究了部分食品中细菌检测的样品前处理方法,应用于糕点和饮料样品中细菌的测定,加标回收率范围为82.1%～115%.检测结果与传统培养方法检测结果相关性良好.     

A fuzzy blue sky catastrophe

In this paper, a blue sky catastrophe of limit cycles of a Van der Pol system with fuzzy disturbances is studied by means of the fuzzy generalized cell mapping (FGCM) method. The blue sky catastrophe happens when a fuzzy limit cycle collides with a fuzzy saddle on the basin boundary as the intensity of fuzzy noise reaches a critical value. The fuzzy limit cycle, characterized by its global topology and membership function, suddenly loses stability and disappears into the blue sky after the collision. We illustrate this bifurcation event by considering the Van der Pol system under the multiplicative fuzzy noise. Such a bifurcation is a fuzzy noise-induced effect which cannot be seen in deterministic systems.     

Coupling routes to hexafluoro-1,3-butadiene, substituted-1,3-fluorine-containing butadienes and fluorinated polyenes

Hexafluoro-1,3-butadiene was readily prepared via a variety of self-coupling processes, such as Cu(0) mediated self-coupling of iodotrifluoroethene, Pd(0) catalyzed coupling of iodotrifluoroethene with the trifluorovinylzinc reagent, and CuBr₂ mediated coupling of the trifluorovinylzinc reagent. Perfluoro-2,3-dimethyl-1,3-butadiene was readily synthesized by the reaction of pentafluoropropenyl-2-zinc reagent with either CuBr₂ or FeCl₃. Alternatively, perfluoro-2,3-dimethyl-1,3-butadiene was prepared by oxidation of the pentafluoropropenyl-2-copper reagent with dioxygen. Cu(0) mediated coupling of an (E)-substituted ,β-difluoro-β-iodostyrene provided the first useful route to a (Z)(Z)-1,4-diaryl-1,3-tetrafluorobutadiene. Extension of the Cu(0) mediated coupling methodology to a perfluorodienyl iodide demonstrated a useful stereospecific route to perfluoropolyenes.     

Yunnandaphninines F and G,New C30 Alkaloids from Daphniphyllum yunnanense

Eight C₃₀ Daphniphyllum alkaloids, including two new ones, yunnandaphninines F and G ( 1 and 2 , resp.), were isolated from the leaves and stems of Daphniphyllum yunnanense. Their structures were elucidated on the basis of the spectroscopic data.     

Study of the spectrum of (3, 1) band in the dΔ-aΠ system of CO

Six hundred and sixty-one spectral lines of the (3, 1) band in the d³Δ-a³Π system of CO in the range of 13,410-13,920 cm⁻¹ were observed employing optical heterodyne magnetic rotation enhanced concentration modulation spectroscopy. Improved molecular constants of the upper vibrational level involved were obtained by a non-linear least-squares weighted fitting procedure using effective Hamiltonians with those of the lower levels fixed at the values obtained in the sub-millimeter region, and the improvements are around one order of magnitude.     

High performance thermosets from a curable Diels–Alder polymer possessing benzoxazine groups in the main chain

A high‐molecular‐weight polymer (PBz) possessing reactive benzoxazine groups in the main chain was prepared through the Diels–Alder reaction using bis(3‐furfuryl‐3,4‐dihydro‐2H‐1,3‐benzoxazinyl)isopropane (BPA‐FBz) and bismaleimide (BMI) as monomers. The chemical structure of PBz is characterized with FTIR and ¹H NMR. The polymer PBz was further thermally reacted with a high performance polymer (PBz‐R) through the ring‐opening addition reaction of benzoxazine groups and the addition reaction of maleimide groups. PBz‐R exhibit a high glass transition temperature of 242 °C, good thermal stability, high flame retardancy, high mechanical strength, and great flexibility. Another crosslinked polymer (PBz‐BR) curing from the mixture of BPA‐FBz and BMI was also prepared. The properties of PBz‐BR are also attractive but, however, not as good as what observed with PBz‐R. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6509–6517, 2008     

Specific stimuli‐responsive antipolyelectrolyte swelling of amphiphilic gel based on methacryloxyethyl dimethyloctane ammonium bromide

An amphiphilic electrolyte, methacryloxyethyl dimethyloctane ammonium bromide (MODAB), was synthesized by quaternization of dimethylaminoethyl methacrylate (DMAEMA) with 1‐bromooctane. Then amphiphilic PMODAB gel was synthesized by radiation cross‐linking with ethyleneglycol dimethacrylate as cross‐linker. PMODAB gels possess distinguished different swelling behaviors with those of DMAEMA hydrogels: (1) Antipolyelectrolyte phenomenon was observed in NaCl solution, that is, a remarkable increment of equilibrium degree of swelling (EDS) in the low NaCl concentration region (10^?4 to 10^?3 mol L^?1), followed by a significant decrease (10^?3 to 0.2 mol L^?1), and a collapsed state (>0.2 mol L^?1); (2) Compared with PDMAEMA, PMODAB was a temperature‐sensitive polymer which showed an upper critical solution temperature (UCST) behavior. The EDS of PMODAB gel dramatically increased at the UCST; (3) In the 0.2 mol L^?1 NaCl solutions, PMODAB gel swelled more significantly in a basic condition (pH > 10) than that in an acidic condition. The special volume phase transition behavior of PMODAB gel is ascribed to the hydrophobic interaction between octyl groups and the formation of ion‐cluster between tetra‐alkyl ammonium cation and Br^?, which lead to the aggregation of gel structure and could be affected by the composition and temperature of the surrounding solution. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 473–480, 2008