Synthesis of the nano-magnetic ionic liquid based on caffeine and its catalytic application in the synthesis of xanthenes

Research on Chemical Intermediates - In this research, a novel nano-sized cube-shaped magnetic ionic liquid based on caffeine was synthesized and characterized by various spectroscopic and...     

Magnetic nanoporous MCM‐41 supported ionic liquid/palladium complex: An efficient nanocatalyst with high recoverability

In this study, a novel magnetic mesoporous MCM‐41 silica supported ionic liquid/palladium complex (Fe₃O₄@MCM@IL/Pd) with core‐structure was prepared and characterized and its catalytic performance was developed under green conditions. The Fe₃O₄@MCM@IL/Pd was prepared via a post grafting method and was characterized using Fourier transform infrared spectroscopy, thermal gravimetric analysis, wide‐ and low‐angle powder X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, vibration sample magnetometer and energy‐dispersive X‐ray analyses. This was applied as an efficient and recoverable nanocatalyst for the one‐pot synthesis of pyrano[2,3‐d]pyrimidine derivatives under ultrasonic conditions. The catalyst was magnetically recovered and reused for 12 consecutive cycles without significant loss of its activity and selectivity.     

Preparation of Ag‐doped g‐C3N4 Nano Sheet Decorated Magnetic γ‐Fe2O3@SiO2 Core–Shell Hollow Spheres through a Novel Hydrothermal Procedure: Investigation of the Catalytic activity for A3, KA2 Coupling Reactions and [3 + 2] Cycloaddition

Taking advantageous of both g‐C₃N₄ and magnetic core‐shell hollow spheres, for the first time a heterogeneous and magnetically separable hybrid system was prepared through a novel and simple hydrothermal procedure and used for immobilization of bio‐synthesized Ag(0) nanoparticles. The hybrid system was fully characterized by using SEM/EDS, FTIR, VSM, TEM, XRD, TGA, DTGA, ICP‐AES, BET and elemental mapping analysis. The catalytic utility of the obtained system, h‐Fe₂O₃@SiO₂/g‐C₃N₄/Ag, for promoting ultrasonic‐assisted A³, KA² coupling reactions and [3 + 2] cycloaddition has been confirmed. The results established that the catalyst could efficiently catalyze the reaction to afford the corresponding products in high yields in short reaction times. The reusability study confirmed that the catalyst could be recovered and reused for at least five reaction runs with only slight loss of the catalytic activity. The hot filtration test also proved low silver leaching, indicating the heterogeneous nature of the catalysis.     

Au‐dimercaprol functionalized cellulose aerogel: Synthesis,characterization and catalytic application

A new derivative of cellulose aerogel was prepared via functionalization of cellulose with dimercaprol. Dimercaprol, as a chelating agent of Au(III), was applied for the loading of Au(III) on cellulose aerogel. The new organogold compound after characterization was used as an efficient heterogeneous catalyst in the oxidation reactions of aliphatic alcohols, benzyl alcohol, and ethylbenzene. Excellent selectivities and good conversions were obtained in the green oxidation reactions of alcohols and ethylbenzene. The high porosity of cellulose aerogel led to the good conversions with the low catalyst amounts. The significance of the presented work is the introducing of an environmentally benign process for the oxidation reactions based on a biocompatible catalyst.     

Chemoselective trimethylsilylation of alcohols catalyzed by saccharin sulfonic acid

Abstract  Saccharin sulfonic acid was easily prepared by the reaction of saccharin with neat chlorosulfonic acid at room temperature. This reagent is efficiently able to catalyze the chemoselective trimethylsilylation of alcohols with hexamethyldisilazane in the presence of amines and thiols. Graphical abstract        

Voltammetric studies of sumatriptan on the surface of pyrolytic graphite electrode modified with multi-walled carbon nanotubes decorated with silver nanoparticles

Multi-walled carbon nanotube decorated with silver nanoparticles (AgNPs-MWCNT) is used as an effective strategy for modification of the surface of pyrolytic graphite electrode (PGE). This modification procedure improved colloidal dispersion of the decorated MWCNTs in water, affording uniform and stable thin films for altering the surface properties of the working electrode. Robust electrode for sensing applications is obtained in a simple solvent evaporation process. The electrochemical behavior of sumatriptan (Sum) at the bare PGE and AgNPs-MWCNT modified PGE is investigated. The results indicate that the AgNPs-MWCNT modified PGE significantly enhanced the oxidation peak current of Sum. A remarkable enhancement in microscopic area of the electrode together with strong adsorption of Sum on the surface of the modified electrode resulted in a considerable increase in the peak current of Sum. Experimental parameters, such as scan rate, pH, accumulation conditions and amount of the modifier used on the PGE surface are optimized by monitoring the CV responses toward Sum. It is found that a maximum current response can be obtained at pH 7.4 after accumulation at open circuit for 150 s. Further experiments demonstrated that the oxidative peak currents increased linearly with Sum concentration in the range of 8.0 × 10⁻⁸-1.0 × 10⁻⁴ mol L⁻¹ with a detection limit of 4.0 × 10⁻⁸ mol L⁻¹. The modified electrode showed high sensitivity, selectivity, long-term stability and remarkable voltammetric reproducibility in response to Sum. These excellent properties make the prepared sensor suitable for the analysis in pharmaceutical and clinical preparations. The modified electrode was successfully applied for the accurate determination of trace amounts of Sum in pharmaceutical preparations.     

Synthesis,Characterization and X‐ray Structures of AMTT‐Type Schiff bases and two CuI Complexes (AMTT= 4‐amino‐5‐methyl‐2H‐1,2,4‐triazole‐3(4H)‐thione)

The reaction of 4‐amino‐5‐methyl‐2H‐1,2,4‐triazole‐3(4H)‐thione (AMTT) with 4‐methylbenzaldehyde and 4‐methoxybenzaldehyde in ethanol led to the iminic derivatives ‐4‐(4‐methylbenzylideneamino)‐5‐methyl‐2H‐1,2,4‐triazole‐3(4H)thione ( L1 ) and 4‐(4‐methoxybenzyl‐ideneamino)‐5‐methyl‐2H‐1,2,4‐triazole‐3(4H)‐thione ( L2 ). The reaction of L1 with CuCl in the presence of triphenylphosphane as co‐ligand in methanol/chloroform solution gave the Cu^I complex containing L1 , [Cu( L1 )(PPh₃)₂Cl]·0.5CH₃OH·0.25CHCl₃ ( 1 ). Treatment of L2 with the same metal salt in a molar ratio of 1:1 in methanol and further addition of a solution of PPh₃ in chloroform led to the complex [Cu( L2 )(PPh₃)₂Cl]·2.5CHCl₃ ( 2 ). The complexes and L1 were characterized by IR and NMR spectroscopy as well as by X‐ray diffraction studies. In both complexes, the Schiff base ligand is coordinated to the copper ion through its sulfur atom. The other coordination sites around the copper ion are occupied by two triphenylphosphane molecules and one chloride ion. Therefore, each Cu^I ion is in a distorted tetrahedral environment. Crystal data for L1 at ?100 °C: space group P2₁/n with a = 720.5(1), b = 1140.6(1), c = 1426.3(2) pm, β = 91.25(1)°, Z = 4, R₁ = 0.03, for 1 at ?120 °C : space group with a = 1286.3(1), b = 1740.3(1), c = 2060.2(1) pm, α = 79.085(6), β = 83.827(5), γ = 76.688(6)°, Z = 4, R₁ = 0.0649 and for 2 at ?80 °C : space group with a = 1183.7(2), b = 1370.1(2), c = 1812.1(3) pm, α = 85.69(2), β = 88.52(2), γ = 64.89(2)°, Z = 2, R₁ = 0.0488.     

Synthesis of pyrazol-quinazolinones and 2,3-dihydroquinazolin-4(1H)-ones using CoAl2O4 nanoparticles as heterogeneous catalyst

Journal of the Iranian Chemical Society - The preparation and characterization of cobalt aluminate (CoAl2O4) magnetic nanoparticles and its application as a catalyst for the synthesis of a novel...     

Computational assisted electrochemical studies for 1,4-diazabicyclo[2,2,2]octane determination at multiwalled carbon nanotube paste electrode

A multiwalled carbon nanotube-modified carbon paste electrode (MWCNT-PE) was used for determination of 1,4-diazabicyclo[2,2,2]octane (DABCO or TEDA) in 0.1 M phosphate buffer solutions (pH 10.25). Cyclic voltammetry(CV) and differential pulse voltammetry (DPV) techniques were used to investigate the electrocatalytic oxidation of DABCO at the surface of modified electrode. The results shown that the oxidation peak current of DABCO at the surface of MWCNT-PE was 2.40 times larger than that at the bare electrode. The experimental formal redox potential (E°') of DABCO was obtained 986 mV versus SHE (Standard Hydrogen Electrode). Density functional theory (DFT) method at B3LYP/6-311++G** level of theory and a conductor-like Polarizable Continuum Model (CPCM) was used to calculate the E°' values. The highest occupied molecular orbital (E _HOMO), lowest unoccupied molecular orbital (E _LUMO) and some thermodynamic parameters such as Gibbs free energy of DABCO and its oxidation forms were calculated. Both direct and indirect methods were used to calculate the theoretical standard electrode potential for DABCO and the results were found to be in good agreement with the experimental values.