Bioanalytical methods applied to endocrine disrupting polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans. A review

The usual methods for determining polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF) and polychlorinated biphenyls (PCB) are generally expensive and time consuming. This fact has favored the development of faster and cheaper techniques, based on immunoassays and bioassays. This paper reviews these bioanalytical methods and their analytical importance at the present moment.     

Use of Tetramethylthiuram Disulfide in Synthesis of Nitrogen-containing Heterocyclic Compounds

We have developed a method for synthesis of aryl isothiocyanates by means of thiocarbamoylation of aromatic amines by tetramethylthiuram disulfide followed by degradation of the intermediate N₍₁₎-aryl-N,N-dimethylthiourea by concentrated HCl. We have shown that thiocarbamoylation of 4-amino-5-ethyl-4H-1,2,4-triazole-3-thiol occurs at the 2 position of the triazole ring, while thiocarbamoylation of 4-amino-3-methyl-6-phenyl-4,5-dihydro-1,2,4-triazin-5-one leads to the dihetaryl-substituted thiourea. We consider the possibility of using N₍₁₎-aryl-N,N-dimethylthioureas as analogs of isothiocyanates in reactions with N-nucleophiles.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 775–780, May, 2005.     

Structure of Cyclic Aryl Thioester Dimer Based on o-Phthaloyl Dichloride and Bis(4-mercaptophenyl) Sulfide

IntroductionTheadvantageofmacrocyclicoligomersasprecursorsforthepreparationofhighperformancepolymersviaring openingpolymerization (ROP)hassparkedmuchinterestintheareaofadvancedthermoplasticcomposites.1 3Andaseriesofcyclicoligomerssuchascarbonates,4 arylesters ,5,6 ethers,7amides8andsulfides9,10 hasbeensuccessfullysynthesized .Recently ,Nishikuboetal.11reportedakindofnovelmacro cyclicoligomerscontainingthioestergroupspreparedbycon densationofbis(4 mercaptophenyl)sulfidewitharomaticaciddichlo…     

New method for the synthesis of cage and polymeric metallosiloxanes

Cage organometallosiloxanes were synthesized according to a new procedure using monomeric organoalkoxysilanes as the starting compounds. The latter were subjected to hydrolysis immediately before the exchange reaction of sodium silanolate with metal halides. Difficultly accessible metallovinylsiloxanes, metallomethylsiloxanes, and metallosiloxanes containing a functional group in the organic radical at the silicon atom can be readily prepared according to the method proposed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2530–2532, December, 1998.     

Synthesis and Characterization of Novel Organosoluble Methyl Substituted Poly(aryl Ether Ketone)s Containing Sulfone Linkage

Several new methyl substituted poly(aryl ether ketone)s containing sulfone linkage with inherent viscosities of 0.62–0.84 dL/g have been prepared from 4,4′‐bis(2‐methylphenoxy)diphenylsulfone and 4,4′‐bis(3‐methylphenoxy)diphenylsulfone with terephthaloyl chloride and isophthaloyl chloride by electrophilic Friedel‐Crafts acylation in the presence of DMF with anhydrous AlCl₃ as a catalyst in 1,2‐dichloroethane, respectively. These polymers having weight‐average molecular weight in the range of 71,000–49,000 are all amorphous and show high glass transition temperatures ranging from 167 °C to 191 °C, excellent thermal stability at temperatures over 400 °C in air or nitrogen, high char yields of 51–58% in nitrogen and good solubility in CHCl₃ and polar solvents such as DMF, DMSO and NMP at room temperature.     

Electrooxidative C–H thiocyanation of hetarenes: voltammetric assessment of thiocyanogen reactivity

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Facile polyethylene glycol (PEG-400) promoted synthesis of β-ketosulfones

An efficient and convenient synthesis of β-ketosulfones is described. Reaction of an α-haloketone with sodium alkyl/aryl sulphinate yields the corresponding β-ketosulfone promoted by polyethylene glycol (PEG-400) as an efficient reaction medium.     

CuI催化的酰胺和溴苯的偶联反应研究

本文报道了一种新的催化体系 (CuI / 氨基酸 / K₃PO₄) 催化胺和芳香溴代化合物之间的交叉偶联反应，对于不同的底物都以较好的产率得到了产物。该反应操作简单，适用性广，并且试剂价格便宜。     

Palladium-catalyzed Suzuki-Miyaura couplings of potassium aryl trifluoroborates with 4-tosyloxycoumarins or 4-tosyloxyquinolin-2(1H)-one

Pd(PPh₃)₄ catalyzed Suzuki-Miyaura cross-coupling reactions of 4-tosyloxycoumarins or 4-tosyloxyquinolin-2(1H)-one with various potassium aryl trifluoroborates afforded the corresponding 4-substituted coumarins or 4-substituted quinolin-2(1H)-ones in good to excellent yield.     

C→N Migrations of the ethoxycarbonyl group in reactions of ortho-substituted aryl isocyanates with the 1,3-zwitterion derived from triisopropylphosphine and ethyl 2-cyanoacrylate

The reactions of meta—para-substituted aryl isocyanates with phosphorus-containing 1,3-zwitterions, which proceed with the CN migration of the CO₂Et group to form the corresponding carbamates, were extended to ortho-substituted aryl isocyanates. The influence of the steric and electronic effects of the ortho substituents in the aromatic rings of aryl isocyanates on the ease of this rearrangement is qualitatively considered.