An Easy One-Pot Procedure for the Synthesis of <Emphasis Type="Italic">N</Emphasis>-Sulfonyl Phosphorous Ylides and Sulfonyl Iminophosphoranes

Summary. Reaction of triphenylphosphine and an electron deficient acetylenic ester in the presence of strong N–H acid such as alkyl and aryl sulfamides or acetamide produces phosphorous ylides at room temperature in CH₂Cl₂. The aryl sulfamide phosphoranes undergo a smooth transformation reaction in boiling toluene and produce iminophosphoranes.     

光学活性甲苄菊酯的合成及其结构与活性关系的研究

本文改进了Goffinet方法,完成了(±)-trans菊酸的拆分;改进了Campbel?方法,只用一种拆分剂(奎宁)完成了对(±)-cis菊酸的拆分。用IR、~1HNMR、旋光度测定等方法确定了各甲苄菊酯光学异构体的结构。生物试验表明结构与活性有如下关系:1,各异构体中以1R-酯的杀虫活性为高,尤其(-)-(1R,3R)-trans甲苄菊酯对全部测试昆虫均显示较高的杀虫活性;2,昆虫不同,各异构体的活性次序也略有差异。     

Host-guest complexes of crown ethers with HN-proton-donor molecules

Crown ethers were reacted with HN-proton-donor molecules to obtain crystalline molecular host-guest complexes. It was found that complexes with crown ethers of different structure are formed, depending on the linear dimensions and mode of steric shielding of active centers of the proton-donor molecules.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 12, 2004, pp. 2030–2033.Original Russian Text Copyright © 2004 by Wang, Ganin.This revised version was published online in April 2005 with a corrected cover date.     

Molecular Beam Mass Spectrometry System for Characterization of Thermal Plasma Chemical Vapor Deposition

A molecular beam mass spectrometry system for in situ measurement of the concentration of gas phase species including radicals impinging on a substrate during thermal plasma chemical vapor deposition (TPCVD) has been designed and constructed. Dynamically controlled substrate temperature was achieved using a variable thermal contact resistance method via a backside flow of an argon/helium mixture. A high quality molecular beam with beamtobackground signal greater than 20 was obtained under film growth conditions by sampling through a small nozzle (75 m) in the center of the substrate. Mass discrimination effects were accounted for in order to quantify the species measurements. We demonstrate that this system has a minimum detection limit of under 100 ppb. Quantitative measurements of hydrocarbon species (H, H₂, C, CH₃, CH₄, C₂H₂, C₂H₄) using Ar/H₂/CH₄ mixtures and silicon species (Si, SiH, SiH₂, SiCl, SiCl₂, Cl, HCl) using Ar/H₂/SiCl₄ mixtures were obtained under thermal plasma chemical vapor deposition conditions.     

Polystyrene/thermoplastic starch blends with different plasticizers

Conventional plastics has a large impact in increasing the environment’s pollution. That’s why the interest has turned towards novel partially and completely biodegradable polymers. In this work, blends of polystyrene and thermoplastic starch with glycerol and Buriti (Mauritia flexuosa L.) oil as plasticizers were prepared. Samples were analyzed using TG/DTG and DSC techniques. The TG results indicated that the blends with Buriti oil are thermally more stable than those with glycerol. The DSC analysis that Buriti oil provides a higher degree of plasticization of PS, compared to the blends plasticized using glycerol under the studied conditions.     

Synthesis and structural characterization of a fully conjugated macrocyclic tetraaza(14)-membered Schiff base and its bivalent metal complexes

A novel 14-membered macrocyclic Schiff base derived from 3-cinnamalideneacetoacetanilide and o-phenylenediamine acts as a tetradentate and strongly conjugated ligand to form a cationic solid complex with CuCl₂/NiCl₂/CoCl₂/ZnCl₂. The ligand and the complexes were characterized by the usual spectral and analytical techniques. The main i.r. band of the macrocyclic Schiff base was compared to that of its metal complexes. The C=N bands are shifted to the lower wave number. The cyclic voltammogram of the copper complex shows that the macrocyclic ligand is able to stabilize the copper(III) oxidation state. The e.s.r. spectra of the copper complex in DMSO solution at room temperature and liquid N₂ temperature were recorded and their salient features thoroughly discussed. The antimicrobial screening tests were also recorded and gave good results in the presence of metal ions in the ligand system.     

On the mechanism of electroluminescence emission by porous silicon layers

The analytical treatment of a model considering the electrooxidation of p-porous silicon layers under galvanostatic conditions is able to give account of experimental facts such as the shape and location of the electroluminescence peak as well as of the spectral shift of the electroluminescence peak produced by oxidation. The proposed model considers electroluminescence to be the result of electron injection into the conduction band by an adsorbed intermediate produced by electrooxidation of the surface coverage with hydrogen or siloxene of the silicon nanocrystallites. The access of holes to the surface is made possible by low accumulation layer conditions and is the rate determining step in the electroluminescence mechanism. In this way it is possible to give a satisfactory explanation to the shift towards the blue experimented by the electroluminiscence emission maximum as a consequence of electrooxidation.     

Poly[3-(3,4-dihydroxyphenyl)glyceric acid] from Stems of <Emphasis Type="Italic">Symphytum asperum</Emphasis> and <Emphasis Type="Italic">S. caucasicum</Emphasis>

Two high-molecular-weight (>1000 kDa) water-soluble preparations were isolated from stems of Symphytum asperum and S. caucasicum. Their basic component was established as poly[hydroxy-1-carboxy-2-(3,4-dihydroxyphenyl)ethylene], analogous to that of high-molecular-weight (>1000 kDa) preparations from roots of these same plants, using IR and NMR spectral data. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 303–305, July–August, 2005. An erratum to this article is available at .     

An overview of laboratory performance studies conducted by the IAEA for marine pollution studies of metals and organic contaminants

Aspects of the International Atomic Energy Agency (IAEA) Analytical Quality Control Services (AQCS) for marine environmental studies are discussed, focusing on recent laboratory performance studies (LPS) and the production of reference materials for trace metals and organic compounds in various marine matrices. The IAEA has organized seventeen global interlaboratory studies for a range of organic contaminants. Of note has been the inclusion of numerous polychlorinated biphenyl congeners (PCBs) and some sterols of anthropogenic origin. Concurrently, there have been eleven worldwide intercomparison exercises for trace metals in the marine environment, most of which included methylmercury. Although such interlaboratory studies can help improve performance in individual laboratories and regional laboratory networks, the results reveal that problems remain in the determination of some metals and many organic contaminants.