Diastereoselective Synthesis of γ-Butenolides Catalyzed by Potassium tert-Butoxide

Potassium tert-butoxide (0.1 mol%) catalyzed a vinylogous Mukaiyama aldol reaction between aromatic and aliphatic aldehydes with 2-(trimethylsilyloxy)furan. The corresponding γ-butenolides were obtained in good yields with good diastereoselectivities.     

Electrophoretic separation of gold nanoparticles according to bifunctional molecules‐induced charge and size

Gold nanospheres modified with bifunctional molecules have been separated and characterized by using agarose gel electrophoresis as well as optical spectroscopy and electron microscopy. The electrophoretic mobility of a gold nanosphere capped with 11‐mercaptoundecanoic acid (MUA) has been found to depend on the number of MUA molecules per gold nanosphere, indicating that it increases with the surface charge of the nanoparticle. The extinction spectrum of gold nanospheres capped with MUA at an MUA molecules per gold nanosphere value of 1000 and connected via 1,6‐hexanedithiol (HDT) decreases by 33% in magnitude and shifts to the red as largely as 22 nm with the increase of the molar ratio of HDT to MUA (R_HM). Gold nanospheres capped with MUA and connected via HDT have been separated successfully using gel electrophoresis and characterized by measuring reflectance spectra of discrete electrophoretic bands directly in the gel and by monitoring transmission electron microscope images of gold nanoparticles collected from the discrete bands. Electrophoretic mobility has been found to decrease substantially with the increment of HDT to MUA, indicating that the size of aggregated gold nanoparticles increases with the concentration of HDT.     

Kinetics for the Reaction between Potassium Ferricyanide and Cobalt Chloride in Aqueous Solution and Microemulsion

The kinetics for the reaction between potassium ferricyanide (K₃Fe(CN)₆) and cobalt chloride (CoCl₂) in aqueous solution and water/bis(2-ethylhexyl) sodium sulfosuccianate (AOT)/isooctane microemulsions were studied by three-wavelength spectrophotometry at 298.2 K. The second-order rate constants (k₂) were calculated from the time dependence of the concentration of reactant K₃Fe(CN)₆. The result showed that the reaction rates in water/AOT/isooctane microemulsions were slower than that in the aqueous solution, and k₂ decreased with molar ratio (ω) of water to AOT in microemulsions, which was interpreted by the transition state theory and confirmed that the reaction took place at the interfaces of the microemulsion water pools.     

双功能配体促进的钯催化不对称醚化和胺化反应（英文）

研究双亚砜膦配体(BiSO-P)亚砜基团的Bronsted碱性在协同催化反应中的作用.1H NMR研究表明双亚砜膦与醇和胺等质子试剂形成氢键;并将此类配体应用于钯催化的不对称醚化和胺化反应,最高获得99%ee.研究发现氢键的存在能有效提高反应的ee值,配体亚砜基团在反应过程中同时起着Lewis和Bronsted碱的作用.     

Concurrent synthesis of vanillin and isovanillin

A method for concurrent synthesis of vanillin and isovanillin has been developed by a nonregioselective Vilsmeier–Haack reaction of O-alkyl guaiacols. O-Alkylation of guaiacol provided the corresponding O-alkyl guaiacol (1), which was then formylated with N-methylformanilide/phosphorus oxychloride to give a mixture of 4-alkoxy-3-methoxy-benzaldehyde (2) and 3-alkoxy-4-methoxybenzaldehyde (3). Finally, the obtained mixture underwent a selective dealkylation by anhydrous aluminium trichloride, while leaving methyl groups intact to simultaneously achieve the significant fine chemicals vanillin and isovanillin.     

Simple power supply for power load controlled isoelectric focusing

The power supply for IEF based on features of the Cockcroft‐Walton voltage multiplier (CW VM) is described in this work. The article describes a design of the IEF power supply, its electric characteristics, and testing by IEF analysis. A circuit diagram of the power supply included two opposite charged branches (each consisting of four voltage doublers). The designed CW VM was powered by 230 V/50 Hz alternate current and it generated up to 5 kV and 90 mW at the output. Voltage and current characteristics of the power supply were measured by known load resistances in the range from 10 kΩ to 1 GΩ, which is a common resistance range for IEF strip geometry. Further, the power supply was tested by a separation of a model mixture of colored pI markers using a 175 × 3 × 0.5 mm focusing bed. Automatically limited power load enabled analysis of samples without previous optimization of the focusing voltage or electric current time courses according to sample composition. Moreover, the developed power supply did not produce any intrinsic heat and was easy to set up with cheap and commonly available parts.     

Photo-oxidation of polyhydroxyl molecules on TiO2 surfaces: from hole scavenging to light-induced self-assembly of TiO2-cyclodextrin wires

First-principles calculations are carried out to study photo-oxidation of glucose, as a prototype of polyhydroxyl carbohydrates and alcohols, on TiO2 surfaces. We reveal the microscopic mechanisms for the separation and transfer of photogenerated electrons and holes at the TiO2-molecule interface as detailed from hole trapping, deprotonation, to the formation of an electron-hole recombination center. These revealed mechanisms further lead to the understanding of the light-induced self-assembly mechanism for TiO2-cyclodextrin nanowires.     

Oxidation of aromatic sulfides with molecular oxygen: Controllable synthesis of sulfoxides or sulfones

The recent development of selective oxidation of aromatic sulfides with molecular oxygen was highlighted. The sulfoxides and sulfones could be obtained by simply switching the reaction media, i.e., bis(2-butoxyethyl)ether (BBE) or poly(ethylene glycol)dimethyl ether (PEGDME). The application of the high-boiling-point polyether as an initiator and green media can eliminate the need of large quantities of additives and volatile solvents. This strategy represents an economic and eco-friendly method that could find potential applications.