β-Silylacrylate as a Multipurpose Reagent in Organic Synthesis

Acrylates are well known electrophilic alkenes having multitude of applications in organic synthesis. They are very good acceptors in Michael addition reactions and are good enophile/dienophile/dipolarophile partners in cycloaddition reactions. Replacing the β-alkyl/aryl groups in acrylates by a silicon group would be interesting. In addition to the conventional reactions displayed by acrylates, β-silylacrylates (β-SAs) can show reactivity specifically related to the silicon group. Many conventional organic reactions such as hydrodimerization, organocatalytic asymmetric Michael additions, inter- and intra-molecular Diels–Alder reactions, and asymmetric 1,3-dipolar cycloadditions have been used to generate the complex chemical entities from β-SAs. Some of the reaction outcomes were vastly influenced by the silicon substituent. This review describes the practical synthesis β-SAs and their use as starting point in complex molecule generation including total synthesis of some natural products/bioactive molecules.     

Lanthanide Shift Reagents. Paper 18. Equilibrium Binding Constants for Europium Shift Reagent with Nitrogen Heterocycles

Paper 16 in this series^{1, 2, 3} was concerned with the equilibrium binding constants (K) of the shift reagent Europium tris (2, 2, 6, 6-tetramethylheptane-3, 5-dionate), Eu(thd)₃, with primary, secondary and tertiary amines. One nitrogen heterocycle, pyridine, and two of its derivatives (see Table) were included. In the present paper we describe the binding constants for a further 9 nitrogen containing heterocycles and relate these to basicity and steric effects.     

A Facile Synthesis of Fused Phosphorus-Heterocycle with Bioactivity via Lawesson's Reagent

A convenient one-pot synthesis of fused phosphorus-heterocycles with biological activity via the cyclization reactions of Lawesson's reagent with bifunctional substrates is reported.     

Ammonium Determination in Water Samples by Using Opa-Nac Reagent: A Comparative Study with Nessler and Ammonium Selective Electrode Methods

A selective and sensitive method based on the ammonium derivatisation with o -phthaldialdehyde (OPA) and N -acetyl-cysteine (NAC) has been developed for ammonium determination in real water samples. The proposed procedure has been compared with ammonium reference methods such as Nessler reagent method and ammonium selective electrode. All procedures have been chemometrically tested and compared in terms of the main analytical properties. These procedures have been used to determine ammonium in unknown water samples. The OPA-NAC reagent method does not present any systematic error (proportional or constant), while Nessler reagent presents both of them for some samples assayed. The ammonium selective electrode is free of corrigible systematic errors, however presents amine interference. The OPA-NAC ammonium method is able to achieve a detection limit (LOD) of 0.07 mg/L in the sample, with a linear dynamic range up to 1.4 mg/L of ammonium.     

原子吸收法间接测定泥炭水解物中的还原糖

本文研究是在常规分析基础上，提出的原子吸收法间接测定泥炭水解物中还原糖的方法。并探讨了方法中酸性介质、共存元素的影响等问题。本方法与常规方法比较，具有测定速度快，试剂用量少，准确性、重现性高等优点。     

UV–vis spectroscopic study directly detecting inorganic phosphorus in urine and our reagent kit

The determination of inorganic phosphorus in human urine is very important, since it has diagnostic value in some clinical cases. Here we apply a simple, sensitive and direct method to determine inorganic phosphorus in urine. This new ensemble is prepared by adding ytterbium chloride and pyrocatechol violet in a 2:1 molar ratio in an aqueous solution of 10 mM 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid buffer at pH 7.0. The addition of the urine sample turned the blue ensemble yellow and altered the UV–vis absorption spectra. The ensemble exhibits excellent selectivity for inorganic phosphorus over other constituents of urine. We validate the accuracy of our method by the standard procedure (molybdenum blue assay for phosphate). The detection results are basically consistent with normal excretion of phosphate. Furthermore, we fabricated a new kind of inorganic phosphorus reagent kit, which enables us to inspect phosphate concentrations of urine with the naked eye. Fit for all kinds of various clinic uses, our reagent kit is a hopeful substitute for the molybdenum reagent kit.      

Probing the Effects of Reagent Gas Pressure and Ion Source Temperature for Dimethyl Ether Chemical Ionization of Tricyclic Antidepressants in an External Source Ion Trap Mass Spectrometer

This study examines the reagent gas pressure and ion source temperature dependence for dimethyl ether chemical ionization (DME CI) mass spectra recorded with an external source ion trap mass spectrometer (ITMS). Information for better controls of the reagent gas pressure in order to obtain fair CI spectra is provided. The origin of M^+? ions observed in DME CIMS is discussed in detail. Furthermore, the ion source temperature effect on the DME CI is also investigated.     

卟啉及其配合物在分析化学中应用进展

综述了卟啉及配合物在分析化学中的应用研究进展。重点介绍了其在光度分析、电化学、分子识别、探针等方面的应用。     

Fe（Ⅲ）、Al（Ⅲ）、Ni（Ⅱ）非有机溶剂液－液萃取行为的研究

本文研究了ＰＥＧ（聚乙二醇）－２０００－钍试剂－（ＮＨ＿４）＿２ＳＯ＿４体系对Ｆｅ（Ⅲ）、Ａｌ（Ⅲ）、Ｎｉ（Ⅱ）的非有机溶剂萃取行为。指出在ｐＨ为３．５－６．５（ＮａＡｃ－ＨＡｃ）的水溶液中，有（ＮＨ＿４）＿２ＳＯ＿４存在下，Ｆｅ（Ⅲ）、Ａｌ（Ⅲ）可被ＰＥＧ－２０００相几乎完全萃取，而Ｎｉ（Ⅱ）则基本上不被萃取。从而获得了Ｎｉ（Ⅱ）与Ｆｅ（Ⅲ）、Ａｌ（Ⅲ）混合离子的定量分离。     

Ultrasonic agitation in microchannels

This paper describes an acoustic method for inducing rotating vortex flows in microchannels. An ultrasonic crystal is used to create an acoustic standing wave field in the channel and thus induce a Rayleigh flow transverse to the laminar flow in the channel. Mixing in microchannels is strictly diffusion-limited because of the laminar flow, a transverse flow will greatly enhance mixing of the reactants. This is especially evident in chemical microsystems in which the chemical reaction is performed on a solid phase and only one reactant is actually diffusing. The method has been evaluated on two different systems, a mixing channel with two parallel flows and a porous silicon micro enzyme reactor for protein digestion. In both systems a significant increase of the mixing ratio is detected in a narrow band of frequency for the actuating ultrasound.