Chemoselective synthesis of stable phosphorus ylides containing a β-amino group

A facile and chemoselective one-pot synthesis of stable phosphorus ylides containing a β-amino group has been developed via reaction of triphenylphosphine, dialkyl acetylenedicarboxylate and 1,2-phenylenediamine in the presence of phenol or 2-aminophenol on its own at ambient temperature.     

Détermination directe des constantes cinétiques d'une réaction chimique par microcalorimétrie à conduction application à la saponification des diesters

The kinetic study of competitive consecutive reactions presents difficulties owing to the complexity of the mathematical integration of differential equation systems. Many investigators adopted methods using graphs of experimental data to determine the kinetic constants of a reaction. We propose, in this work, a direct determination of these constants based on thermograms recorded with a Calvet conduction microcalorimeter using a computing program which includes numerical integration of differential equation systems, signal convolution with an experimental function of apparatus (to get rid of the inertness of the detector—recorder system) and the optimization of the adopted model parameters. We applied this exploitation process to the alkaline hydrolysis of some diester of diols or dicarboxylic acids in aqueous solution.     

介孔硅铝分子筛的合成、表征及其作为固体酸催化苯酚与1-辛烯的烷基化反应

以异丙醇铝、硅酸四乙酯和十六烷基三甲基溴化胺为原料,以乙酰丙酮为螯合剂,采用溶胶-凝胶法合成了硅铝比分别为25,50,100和150的介孔硅铝分子筛,并用其催化苯酚与1-辛烯的液相烷基化反应.X射线衍射、N2吸附、高分辨透射电镜及27Al核磁共振光谱表征结果表明,该介孔分子筛具有蠕虫状骨架结构.在160℃时,硅铝比为25的介孔硅铝分子筛催化剂上苯酚可以完全转化为单烷基苯酚.     

Syntheses,spectroscopic study and crystal structures of some new <Emphasis Type="Italic">N</Emphasis>-benzoylphosphoric triamides

The reaction of N-benzoylphosphoramidic dichloride with amines afforded some new N-benzoylphos-phoric triamides with formula C₆H₅C(O)NHP(O)(X)₂, X=NH–CH(CH₃)₂ (1), NH–CH₂–CH(CH₃)₂ (2), NH–CH₂–CH(OCH₃)₂ (3), N(CH₃)[CH₂CH(OCH₃)₂] (4) and N(CH₃)(C₆H₁₁) (5) that were characterized by ¹H,¹³C,³¹P NMR, IR spectroscopy and elemental analysis. The structures have been determined for compounds 4 and 5 by X-ray crystallography. These compounds contain one amidic hydrogen atom and form centrosymmetric dimmers via intermolecular –P–O⋯H–N–hydrogen bonds besides weak C–H⋯O hydrogen bonds that lead to three-dimensional polymeric clusters in the crystalline lattice.     

Calorimetric studies of AgI-doped tellurite glasses

The heat capacity changes during the glass transition of TeO₂---TlO_0.5 glasses containing AgI or (AgI)_0.75(TlI)_0.25 up to mole fractions of 0.4 or 0.55 have been measured by differential scanning calorimetry. The glass transition temperatures of the binary compositions decrease with increasing TlO_0.5/TeO₂ ratio. With rising Ag⁺ concentration, the cohesion of the glass network is weakened and the structural contributions to the relaxation phenomenon as well as its activation enthalpies diminish. There is no interaction between the iodide in probably crystalline form and the host glass network. Compared with binary and ternary silver tellurite glasses, the corresponding thallium tellurite compositions are less stable.     

InCl3-catalyzed efficient synthesis of spiro-perimidine derivatives

InCl₃ was found to be a mild and effective catalyst for the simple and efficient synthesis of spiro-perimidine derivatives by the reaction of naphthalene-1,8-diamine and active carbonyl compounds in water at room temperature. This protocol includes some important aspects like the use of water as a “green” reaction medium, good yielding of products and mild reaction conditions.     

An efficient protocol for acetalization of carbonyl compounds using Zr(HSO4)4 at room temperature under solvent-free conditions

Zr(HSO₄)₄ as a solid acid was applied for the acetalization of carbonyl compounds, at room temperature, under solvent-free conditions with good to excellent yields. The low cost and availability of the reagents, versatile procedure and easy work-up make this method attractive for the organic synthesis of these compounds.     

Rapid and highly selective epoxidation of alkenes by tetrabutylammonium monopersulfate in the presence of manganese meso-tetrakis(pentafluorophenyl)porphyrin and tetrabutylammonium salts or imidazole co-catalysts

Epoxidation of various alkenes in low to high yields (29-100%) and good to excellent selectivities (75-100%) was performed with tetrabutylammonium monopersulfate in the presence of meso-tetrakis(pentafluorophenyl)porphyrin as catalyst and tetrabutylammonium acetate or fluoride or imidazole as co-catalysts in CH₂Cl₂, in less than 10 min at room temperature (∼25 °C).     

8-Hydroxyquinoline Functionalized Graphene Oxide: an Efficient Fluorescent Nanosensor for Zn<Superscript>2+</Superscript> in Aqueous Media

A nanosensor, based on 8-hydroxyquinoline functionalized graphene oxide, was developed for the fluorescence detection of Zn²⁺. It showed high selectivity and sensitivity for Zn²⁺ion in aqueous solution over other metal ions such as Li⁺, Na⁺, Ca²⁺, Mg²⁺, Al³⁺, Cd²⁺, Co²⁺, Cu²⁺, Hg²⁺, Ni²⁺, Pb²⁺, Fe²⁺, Fe³⁺and Cr³⁺. Due to the linearity of the emission intensity toward Zn²⁺ concentration, fluorescent technique could be used for the detection of Zn²⁺ ion even at very low concentrations.     

Synthesis of α‐Aminonitriles and 5‐Substituted 1H‐Tetrazoles Using an Efficient Nanocatalyst of Fe3O4@SiO2–APTES‐supported Trifluoroacetic Acid

Fe₃O₄@SiO₂–APTES‐supported trifluoroacetic acid nanocatalyst was used for the one‐pot synthesis of α‐aminonitriles via a three‐component reaction of aldehydes (or ketones), amines, and sodium cyanide. This method produced a high yield of 75–96% using only a small amount of the catalyst (0.05 g) in EtOH at room temperature. The catalyst was also employed for the synthesis of 5‐substituted 1H‐tetrazoles from nitriles and sodium azide in EtOH at 80°C. The tetrazoles were produced with good‐to‐excellent yields in a short reaction time of 4 h. Both synthetic methods were carried out in the absence of an organic volatile solvent. Because the supported trifluoroacetic acid generated a solid acid on the surface, thus the acid corrosiveness was not a serious challenge. This heterogeneous nanocatalyst was magnetically recovered and reused several times without significant loss of catalytic activity.