A new crystal engineering approach for the synthesis of {[K.18-Crown-6]I3}n as a nanotube-Like and recyclable catalyst for the chemoselective silylation of alcohols

Reaction of 18-crown-6 with KI in ethanol solution followed by addition of iodine (I₂) afforded a unique triiodide salt with a nanotube-like structure ({[K.18-Crown-6]I₃}_n). It is shown that this reagent may be used for the chemoselective trimethylsilylation of alcohols. The synthesis of the crystalline reagent is a good example of crystal engineering. Reagent was recycled and reused.     

Preparation of Silica‐bonded Propyl‐diethylene‐triamine‐N‐sulfamic Acid as a Recyclable Catalyst for Chemoselective Synthesis of 1,1‐Diacetates

A simple and efficient procedure for the preparation of silica‐bonded propyl‐diethylene‐triamine‐N‐sulfamic acid (SPDTSA) by reaction of 3‐diethylenetriamine‐propylsilica (DTPS) and chlorosulfonic acid in chloroform is described. Silica‐bonded propyl‐diethylene‐triamine‐N‐sulfamic acid is employed as a recyclable catalyst for the synthesis of 1,1‐diacetates from aromatic aldehydes and acetic anhydride under mild and solvent‐free conditions at room temperature. Catalyst could be recycled for several times without any additional treatment.     

Synthesis of mono- and bis-spirooxindole derivatives “on water” using double salt of aluminum sulfate–sulfuric acid as a reusable catalyst

Molecular Diversity - The preparation of double salt of aluminum sulfate–sulfuric acid (Al4(SO4)6·(H2SO4)·24H2O) by the reaction of aluminum sulfate and sulfuric acid in water is...     

Adsorption of Pentafluorophenol onto Powdered,Granular, and Cloth Activated Carbons

In the present study, the adsorption of pentafluorophenol from aqueous solution onto granular activated carbon, powdered activated carbon, and activated carbon cloth has been investigated from the equilibrium and kinetic points of view. To the best of our knowledge, the removal of pentafluorophenol from aqueous solution onto activated carbon have not been reported in the literature. The experimental equilibrium data, suitably fitted by the Toth, Langmuir-Freundlich, and Redlich-Peterson isotherms, have shown that the cloth and powdered carbons exhibit the highest adsorption capacity. For all the investigated samples, the experimental kinetic data have been satisfactorily interpreted by a pseudo-second-order model. From the fitting results it has been observed that the highest rate constant and initial rate of adsorption is shown by powdered activated carbon.     

Silica-bonded N-propyl sulfamic acid as an efficient catalyst for the formylation and acetylation of alcohols and amines under heterogeneous conditions

A simple and efficient procedure for the preparation of silica-bonded N-propyl sulfamic acid (SBNPSA) by the reaction of 3-aminopropylsilica (1) and chlorosulfonic acid in chloroform is described. This solid acid is employed as a new catalyst for the formylation of alcohols and amines with ethyl formate under mild and heterogeneous conditions at room temperature with good to excellent yields. Also, SBNPSA catalyzed acetylation of various alcohols and amines with acetic anhydride at room temperature.     

Silica-bonded S-sulfonic acid a recyclable catalyst for the synthesis of coumarins

Silica-bonded S-sulfonic acid(SBSSA) was prepared by the reaction of 3-mercaptopropylsilica(MPS) and chlorosulfonic acid in chloroform.This solid acid has been employed as a recyclable catalyst for the synthesis of coumarins from phenols andβ-ketoesters at 80℃under solvent-free conditions.     

1‐Butyl‐3‐methylimidazolium Hydrogen Sulfate [Bmim]HSO4: An Efficient Reusable Acidic Ionic Liquid for the Synthesis of 1,8‐Dioxo‐Octahydroxanthenes

1‐Butyl‐3‐methylimidazolium hydrogen sulfate [bmim]HSO₄ as an acidic ionic liquid was prepared and used as a catalyst for the synthesis of 1,8‐dioxo‐octahydroxanthenes in excellent yields and short reaction times at 80 °C. The ionic liquid was easily separated from the reaction mixture by water extraction and was recycled four times without any loss in activity.     

Development of efficient method for preconcentration and determination of copper, nickel, zinc and iron ions in environmental samples by combination of cloud point extraction and flame atomic absorption spectrometry

A cloud point extraction procedure for the preconcentration of copper, nickel, iron and zinc ions in various samples has been described. Analyte ions in aqueous phase are complexed with 3-((indolin-3-yl)(phenyl)methyl)indoline (IYPMI) and following centrifugation quantitatively extracted to the aqueous phase rich in Triton X-114. The surfactant-rich phase was dissolved in 2.0 mol L⁻¹ HNO₃ in methanol prior to metal content determination by flame atomic absorption spectrometry (FAAS). The effects of some parameters including, the concentrations of IYPMI, Triton X-114 and HNO₃, bath temperature, centrifuge rate and time were investigated on the recoveries of analyte ions. At optimum conditions, the detection limits of (3 SDb m⁻¹) of 1.6, 2.8, 2.1 and 1.1 ng mL⁻¹ for Cu²⁺, Fe³⁺, Ni²⁺ and Zn²⁺ along with preconcentration factors of 30 and enrichment factor of 48, 39, 34 and 52 for Cu²⁺, Ni²⁺, Fe³⁺ and Zn²⁺ respectively, were obtained. The proposed cloud point extraction has been successfully applied for the determination of metal ions in real samples with complicated matrix such as biological, soil and blood samples with high efficiency.