Silphox [POCl3−n (SiO2) n ] as a New,Efficient, and Heterogeneous Reagent for the Synthesis of Benzimidazole Derivatives Under Microwave Irradiation

Silphox [POCl_3-n(SiO₂)_n] efficiently catalyzes the condensation of benzene-1,2-diamine with mono and dicarboxylic acids under microwave irradiation to afford benzimidazole derivatives in high yields and short reaction times.     

Molybdatophosphoric Acid/NaNO2/Wet SiO2 as an Efficient System for the Aromatization of 1,2‐Dihydroquinolines under Mild and Heterogeneous Conditions

A combination of molybdatophosphoric acid and NaNO₂ in the presence of wet SiO₂ was used as an effective oxidizing agent for the oxidation of 1,2‐dihydroquinolines to their corresponding quinoline derivatives in dichlomethane at room temperature with excellent yields.     

硅胶功能化的N-丙哌嗪固载钯纳米粒子作为有效的多相催化剂用于氰化反应(英文)

An efficient heterogeneous Pd catalytic system has been developed, based on immobilization of Pd nanoparticles (PNPs) on a silica-bonded N-propylpiperazine (SBNPP) substrate. The SBNPP substrate effectively stabilizes the PNPs and improves their stability against aggregation. The catalytic activity of this catalyst was investigated in the cyanation of aryl halides with K4[Fe(CN)6 ] as the cyanide source. The catalyst could be recycled several times without appreciable loss of catalytic activity.     

Silica-bonded S-sulfonic acid: an efficient and recyclable solid acid catalyst for the synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ols)

Silica-bonded S-sulfonic acid (SBSSA) is employed as a recyclable catalyst for the condensation reaction of aromatic aldehydes with 3-methyl-l-phenyl-5-pyrazolone. This condensation reaction was performed in ethanol under refluxing conditions giving 4,4′-alkylmethylene-bis(3-methyl-5-pyrazolones) in 75-90% yields.     

Composition of essential oils in subterranean organs of three species of Valeriana L

Essential oils from the subterranean organs of three species of Valeriana L. from Iran (Valeriana sisymbriifolia Vahl, Valeriana alliariifolia Adams and Valeriana officinalis L.) belonging to Valerianaceae family have been obtained by hydrodistillation and analysed by gas chromatography-mass spectrometry in order to discern the differences and similarities between the volatile chemical compositions of these species. More than 100 components were identified in essential oils of the studied plants (Supplementary Table S1--online only). The principal common constituents of the three species of Valeriana were spathulenol, limonene, γ-terpinene, vulgarone B and p-cymene. The main essential oil ingredients were α-selinene (7.83%) in V. sisymbriifolia, limonene (3.53%) in V. alliariifolia and spathulenol (13.33%), α-campholenal (11.48%), vulgarone B (8.38%) and valerenal (8.32%) in V. officinalis plants. Ageratochromene (precocene II), a chromene substance with antibacterial, antifungal, insecticidal and antijuvenile hormonal activities, was found at high levels (35.59% and 36.58%) in the essential oils of V. sisymbriifolia plants.     

A homotopy analysis method for limit cycle of the van der Pol oscillator with delayed amplitude limiting

In this work, a powerful analytical method, called Liao’s homotopy analysis method is used to study the limit cycle of a two-dimensional nonlinear dynamical system, namely the van der Pol oscillator with delayed amplitude limiting. It is shown that the solutions are valid for a wide range of variation of the system parameters. Comparison of the obtained solutions with those achieved by numerical solutions and by other perturbation techniques shows that the utilized method is effective and convenient to solve this type of problems with the desired order of approximation.     

Silica-bonded N-propylsulfamic acid as a recyclable catalyst for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones

2,3-Dihydroquinazolin-4(1H)-one derivatives are synthesized via a one-pot,three component reaction of isatoic anhydride and an aromatic aldehyde with ammonium acetate or primary amine catalyzed by silica-bonded N-propylsulfamic acid(SBNPSA) in refluxing ethanol.