Novel Catalytic Hydrodechlorination of CCl_2F_2 over Supported PdCl_2-(n-C_4H_9)_4N~+Cl~- Molten salts

Chlorofluorocarbons (CFCs) such as CCl_2F_2 have been widely used as refrigerants, blowing agent etc. due to their remarkable properties, however for the global environmental concerns, they have been prohibited in production and use because of their ozone depletion effect and greenhouse effect1. Nevertheless there are still several million tons of CFCs in use all over the world, close attentions have been paid to the operable handling techniques and environmentally benign alternatives. Amon…     

Photochemical Selective Desilylation of t-Butyldimethylsilyl Ethers

The silyl moiety, e.g., trimethylsilyl (TMS), has been widely used as a protecting group for alcohols or aldehydes and ketones in organic synthesis via formation of alkyl silyl ethers or enol silyl ethers respectively. Generally, the protecting silyl group was removed by fluoride ion1, acid2 or base3. However, these deprotection methods afford little selectivity between silyl alkyl ethers and silyl enol ethers. Recently, photochemical approaches of desilylation have also been developed4-7. K…     

Direct Oxidation of Ethene to Acetic Acid

Compared with the chemical processes of naphtha oxidation, n-butane oxidation, methanol carbonylation and acetaldehyde oxidation currently used in the manufacture of acetic acid, direct selective oxidation of ethene to acetic acid is a very attractive process1,2. Uchida et al.3,5 and Denko4 have reported a highly active catalyst system which produces acetic acid with 240 g/h(L of the STY and 86.4% of selectivity. The catalyst system consisted of 2% of Pd by weight, 0.02 of the mole ratio of …     

A Statistical Examination on the Compensation between the Enthalpies and Entropies Obtained from the Calorimetric Methods

The widely observed enthalpy-entropy compensation in chemistry and biophysics is still in a state of great confusion, because the reported enthalpy-entropy correlations in literature were often found to be false1-3. This problem has promoted Exner4. Krug5, Linert6, and others to develop some statistical methods to examine the compensation between the enthalpies and entropies obtained from the indirect van't Hoff method. However, as pointed out by Connors in a recent review7, it remains untou…     

Double-Mesopore V-MSU-X Silica and its Pure Siliceous Derivative Prepared by One Synthesis System

Since their first disclosure of the M41S family of materials1,2 in 1992, considerable research effort has been developed to prepare the other derivatives of mesoporous materials such as SBA3 and MSU-X4,5 silicates by using different polymeric and oligomeric templates. The later involved different sorts of nonionic poly (ethylene oxide)-based surfactants, which led to the family of MSU-X (X=1-4) and then provided new advantages in either topologies or processing. The interest in these mate…     

Effect of Co-solvent and Pressure on the Thermal Decomposition of 2,2′Azobis-(isobutyronitrile) in Supercritical CO_2

Recently, researchers pay much attention to the polymerization in supercritical (SC) CO2. 2, 2(-Azobis (isobutyronitrile) (AIBN) is a commonly used initiator in free radical polymerization in supercritical CO21. It is well known that the decomposition rate of the initiator AIBN plays an important role for a polymerization process2. Guan et al. have studied the effect of pressure on the decomposition rate of AIBN in SC CO22. A small amount of polar cosolvent can influence the propertie…     

Gnetupendin C, a New Stilbene Dimer from the Lianas of Gnetum Pendulum

Continuous investigation on stilbenoids from the lianas of Gnetum pendulum1 resulted in the isolation of a new dimer, Gnetupendin C (1), a cis-2, 3-dihydrobenzofuran dimer of resveratrol and oxyresveratrol.Gnetupendin C (1) was obtained as yellowish amorphous power, [(] -220.0 (c 0.100, MeOH). UV (c 0.02, MeOH) (max (log (): 222 (4.5), 288 (sh), 310 (sh), 327 (4.4) nm. The high resolution EIMS, m/z 470.1344, agreed with a molecular formula of C28H22O7 (requires 470.1366) and the 1H NM…     

A Hydrogen Peroxide Biosensor Combined HRP Doped Polypyrrole with Ferrocene Modified Sol-gel Derived Composite Carbon Electrode

Conducting polymers, because of bearing many attractive features, for example, shuttling electrons between the electrode surface and the entrapped reagents (enzymes, mediators, etc.) while preventing interference and electrode fouling, have been proposed as enzyme supports for electrochemical biosensors1-4. Polypyrrole, owing to its popularity to water solubility and the mild conditions used for electropolymerization, has been the most widely used monomer to entrap enzymes5-8. The sol-gel prog…     

Electronic Noses Using Quantitative Artificial Neural Network

The present paper covers a new type of electronic nose (e-nose) with a four-sensor array, which has been applied to detecting gases quantitatively in the presence of interference. This e-nose has adapted fundamental aspects of relative error (RE) in changing quantitative analysis into the artificial neural network (ANN). Thus, both the quantitative and the qualitative requirements for ANN in implementing e-nose can be satisfied. In addition, the e-nose uses only 4 sensors in the sensor array, and can be designed for different usages simply by changing one or two sensor(s). Various gases were tested by this kind of e-nose, including alcohol vapor, CO, iiquefied-petrol-gas and CO2. Satisfactory quantitative results were obtained and no qualitative mistake in prediction was observed for the samples being mixed with interference gases.     

测定血浆中微量硒的三元包合物荧光分析法

采用氧瓶燃烧法对血样进行破坏,利用β－环糊精和十二烷基硫酸钠形成包合物的性质,将4,5－苯并苯硒二唑包合,建立了三元包合物荧光分析法,不经萃取,直接测定血浆中的硒。方法的日内精密度为5．4％－9．3％（n＝7）;日间精密度为3．5％－14．5％（n＝7）;线性范围为10－500μg／;回收率为91．0％－97．8％。对新疆汉族、维吾尔族和沈阳汉族58人的血样进行测定,结果表明：新疆汉族与沈阳汉族间血硒值无显著性差异（F＝1．36,P＞0．05）;新疆汉族与维吾尔族间血硒值有非常显著性差异（F＝1．01,P＜0．01）;男女之间血硒值有非常显著性差异（P＜0．01）。