L‐Proline–H2O2: A New Chemoselective Approach for Oxidation of Sulfides to Sulfoxides

A facile and selective oxidation of sulfides to sulfoxides using an L‐proline–H₂O₂ system for structurally divergent sulfide substrates with excellent yields at ambient conditions is reported.     

Facile and One-Pot Synthesis of 2 H -Chromene Derivatives Mediated by Vinyl triphenylphosphonium Salt

An efficient process that converts 2-hydroxybenzaldehyde and their derivetives to chromene derivatives via intramolecular Wittig reaction is described.     

NOVEL AND FACILE SYNTHESIS OF THIOPHENE,THIAZOLE, 2H-PYRAN-2-ONE BENZIMIDAZO[1,2-a]PYRIDINE AND PYRIDINE DERIVATIVES CONTAINING ANTIPYRINE MOIETY

Several new thiophene, thiazole, 2H-pyran-2-one, benzimidazo[1,2-a]pyridine and pyridine derivatives were synthesised from active methylene reagents, 4-chloroacetylantipyrine and enaminones as starting materials.     

Photodegradation of Caffeic Acid in W/O/W Emulsions in the Absence and in the Presence of TiO2

Caffeic acid, a natural phenol with antioxidant and sunscreen activity, can undergo photooxidation upon UV irradiation. The photodegradation of caffeic acid at different concentrations was assessed in water, at pH 4.0 and 6.0, without and with TiO₂. The study was then carried out on W/O/W emulsions entrapping the phenolic acid either in the inner or in the outer aqueous phase in the absence and in the presence of TiO₂, added in the external phase (pH 6.0 or 7.0). The degradation of caffeic acid followed a pseudo-zero order kinetic with an inverse dependence from its initial concentration; at increasing pH of the medium caffeic acid degraded faster. The addition of TiO₂ increased the initial photodegradation rate. Compared with water, W/O/W emulsions protected the phenol towards both the photodegradation and the photocatalytic activity of TiO₂. Multiple systems allowed to incorporate caffeic acid and TiO₂ in the same formulation avoiding any catalytic interactions.     

2-Keto-3-mercaptocinchoninic Acids as Precursors for Novel Thiazino[6,5-c]quinoline-1,5-dione Derivatives

2-Keto-3-mercaptocinchoninic acid derivatives 1a and b react with Schiff's bases 2a–d in toluene at refluxing temperature to give thiazino[6,5-c]quinoline derivatives 4a–h. Also, refluxing of 1a and b with arylazomalononitriles 5a–d in acetic acid afforded the thiazolo[6,5-c]quinoline derivatives 7a–d. The structure of all the newly synthesized products was confirmed based on elemental and spectral data.     

原子吸收光谱测定Sm-Eu-Gd富集物中Sm、Eu、Gd

本文制定了N_2O-C_2H_2焰原子吸收光谱直接测定Sm-Eu-Gd富集物中Sm、Eu和Gd的分析方法。采用氧化镧溶液作为缓冲剂消除干扰提高灵敏度。此法不需要复杂的分离过程。方法简便、快速、成本低、适合工厂采用。     

Preparation and Antibacterial Function of Quaternary Ammonium Salts Grafted Cellulose Fiber Initiated by Fe2 +-H2O2 Redox

The surface contact disinfecting technique is a newly developed method for water sterilization. In this paper, the grafted quaternary ammonium salts (QAS) antibacterial fibers were prepared and designed to apply for the surface contact disinfecting process in water treatment. The antibacterial fibers were directly prepared by grafting methacryloxylethyl benzyl dimethyl ammonium chloride (DMAE-BC) onto cellulose fiber using thiocarbonate-H₂O₂ redox system. All kinds of factors in the grafting reactions, such as reaction time, reaction temperature, monomer concentration, initiator concentration, which influence the percentage of grafting, were studied and optimized. The modified cellulose fibers were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope(SEM). The effects of the percentage of grafting of the grafted cellulose fibers on bactericidal activity were also studied. The spread plate method was used to characterize the bactericidal activity. The disinfection process was further investigated by directly observing the morphology of the bacterial cells adsorbed on the antibacterial fibers with SEM and measuring extracelluar total protein concentration in suspension. The poly(DMAE-BC)-grafted cellulose ?ber was found to exhibit particularly high activity against E.coli.     

Regioselective Synthesis of 1,8-Naphthyridinone-Annulated Oxygen and Sulfur Heterocycles by Tri-n-butyl Tinhydride–Mediated Aryl Radical Cyclization

The tin hydride–mediated cyclizations of a number of ethers, sulfides, and sulfones under mild, neutral conditions have been investigated. While the 2-bromobenzyloxy ethers were prepared in 62–65% yields by the alkylation of 4-hydroxy-1-phenyl-1,8-naphthyridin-2(1H)-one with 2-bromobenzyl bromides in refluxing acetone in the presence of anhydrous potassium carbonate, the sulfides were derived from 4-mercapto-1-phenyl-1,8-naphthyridin-2(1H)-one and 2-bromobenzyl bromides in 82–84% yields by a phase-transfer catalysis (PTC) reaction. The corresponding sulfones were prepared by treatment of the sulfides with m-CPBA in refluxing dichloromethane. The ethers, sulfides, and the sulfones were treated with ⁿ Bu₃SnH-AIBN to give regioselectively 1,8-naphthyridinone-annulated oxygen and sulfur heterocycles in 70–78% yields.     

Efficient Method of Synthesis of N,N′-Disubstituted Ureas/Thioureas by a Zinc Chloride Catalyzed Thermal Reaction

Symmetrically N,N′-disubstituted ureas/thioureas were synthesized by heating amines or phenyl hydrazine and urea/thiourea on a preheated hot plate at 80–85°C under solvent-free conditions in the presence of a catalytic amount of ZnCl₂ as a catalyst. The protocol has the advantages of not using toxic phosgene and other hazardous substrates or organic solvents. Increased reaction rate, good yield, and a simple workup procedure are involved.     

聚乙烯载体催化剂的制备与表征

不同目数的聚乙烯粉末通过辐射方法接枝了4-乙烯基吡啶官能团.经甲基铝氧烷(MAO)预处理后负载了茂金属催化剂Cp₂ZrCl₂.光电子能谱和红外光谱结果表明催化剂通过MAO的作用负载在聚乙烯接枝4-乙烯基吡啶聚合物上.4-乙烯基吡啶的接枝含量、催化剂的负载率以及载体催化剂对乙烯单体的活性均随着聚乙烯粉末的颗粒减小而增大.