Heterogeneous catalysts govern the field of catalysis due to their easy separation from a reaction mixture, reusability, and prevention of agglomeration, making them more efficient catalysts than homogeneous catalysts. Herein, we report the eco-friendly synthesis of a novel heterogeneous catalyst, viz. palladium nanoparticles (Pd NPs) decorated over zeolite 13X nanocomposite using dried fruits of Terminalia chebula Retz. as the reducing and stabilizing agent and its performance as a promising catalyst for the Suzuki–Miyaura coupling reactions. The particle size, crystallinity, morphology, and textural properties of the catalyst were identified using Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HR-TEM), thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) analysis which confirmed the presence of palladium nanoparticles on the surface of zeolite 13X. The FESEM images revealed the presence of spherical-shaped Pd NPs over the cubical particles of zeolite 13X. The average particle size of the palladium nanoparticles was found to be in the range of 6–7 nm and was polycrystalline in nature. From BET analysis, it was inferred that the decoration of Pd NPs decreased the surface area of zeolite 13X (615.5 m2/g to 548.334 m2/g), thus leaving pores unoccupied. This study showed the efficiency of this novel catalyst in the formation of biaryl derivatives using low palladium loadings (0.0012 mol%) giving good to excellent yields (90–99%) within short reaction times (10–225 min) with high TONs (>?79,000) and TOFs (>?21,000). Both electron-donating and electron-withdrawing aryl halides and aryl boronic acids reacted smoothly in the presence of K2CO3 as a base and EtOH/H2O (1:1) as the solvent. Besides, the catalyst could be recycled and reused for 5 consecutive runs with minimal loss of its efficiency. The supremacy of this catalyst could well be exploited in future for various organic transformations.
The structural and solvent effects on the reduction of trans-chloro(RC6H4NH2)bis(1,2-diaminoethane)cobalt(III) ion (R=H, p-Me, p-OMe, p-OEt, p-F, m-Me and m-OMe) by the hexacyanoferrate(II) complex was investigated in aqueous MeOH. The second order rate constants for these reactions were determined spectrophotometrically at three different temperatures and activation parameters have been computed. Reduction proceeding through ion-pair formation is proposed on the basis of the Laidler–Eyring and Grunwald–Winstein equations. The influence of added co-solvent on the reactivity has been analysed using multiple regression equations viz. Kamlet–Taft and Swain. The reduction rates were correlated with Hammett's substituent constants yielding a negative reaction constant. 相似文献
The photoreduction of trans-[Co(NH3)4Cl2]+, trans-[Co(en)2Cl2]+, [Co(dien)Cl3], [Co(trien)Cl2]+, and [Co(tetren)Cl]2+, ions has been studied using a low pressure Hg vapour lamp as light source (254 nm) in aqueous–organic solvents [0–30% (v/v) MeOH or 1,4-dioxane]. Quantum yields for CoII production by redox decomposition have been determined in all the cases, and increase considerably with the increase in concentration of MeOH or 1,4-dioxane in the binary solvent mixtures under investigation. A plot of log(quantum yield) versus the Grunwald–Winstein Parameter, Y, which is a measure of solvent ionizing power, shows that a different blend of general and specific solvent interacts with the solute. This kind of specific solvent interaction on the reactant/excited state has been analysed using multiple regression: viz. Krygowski–Fawcett and Kamlet–Taft equations. Reasons for the difference in reactivity with chelation are also discussed. 相似文献
Ternary rare earth transition metal sulfides LnMS3 with Ln = La, Nd, and Gd, and M = V and Cr; as well as Ln = La and M = Mn, Fe, Co, and Ni have been prepared and characterized. The vanadium and chromium sulfides crystallize in a monoclinic layer structure isotypic with LaCrS3, while the other LnMS3 sulfides crystallize in a hexagonal structure. Chemical shifts of the metal K-absorption edge and XPS binding energies of core levels indicate that the transition metal is trivalent in the V and Cr sulfides, while it is divalent in the Mn, Fe, Co, and Ni sulfides. Electrical and magnetic properties of the sulfides are discussed in terms of their structures and the electronic configurations of the transition metal ions. 相似文献
Bench-Scale studies on the partitioning and recovery of minoractinides from the actual and synthetic sulphate-bearing high level waste (SBHLW) solutions have been carried out by giving two contacts with 30% TBP to deplete uranium content followed by four contacts with 0.2M CMPO+1.2M TBP in dodecane. The acidity of the SBHLW solutions was about 0.3M. In the case of actual SBHLW, the final raffinate contained about 0.4% -activity originally present in the HLW, whereas with synthetic SBHLW the -activity was reduced to the background level.144Ce is extracted almost quantitative in the CMPO phase,106Ru about 12% and137Cs is practically not extracted at all. The extraction chromatographic column studies with synthetic SBHLW (aftertwo TBP contacts) has shown that large volume of waste solutions could be passed through the column without break-through of actinide metal ions. Using 0.04M HNO3>99% Am(III) and rare earths could be eluted/stripped. Similarly >99% Pu(IV) and U(VI) could be eluted.stripped using 0.01M oxalic acid and 0.25M sodium carbonate, respectively. In the presence of 0.16M SO
42–
(in the SBHLW) the complex ions AmSO
4+
, UO2SO4, PuSO
42+
and Pu(SO4)2 were formed in the aqueous phase but the species extracted into the organic phase (CMPO+TBP) were only the nitrato complexes Am(NO3)3·3CMPO, UO2(NO3)2·2CMPO and Pu(NO3)4·2CMPO. A scheme for the recovery of minor actinides from SBHLW solution with two contacts of 30% TBP followed by either solvent extraction or extraction chromatographic techniques has been proposed. 相似文献
The title compound, methyl (2aS,3R,5R,5aS,6S,6aS,8R,9aS,10aR,10bR,10cS)‐8‐(3‐furyl)‐2a,4,5,5a,6,6a,8,9,9a,10a,10b,10c‐dodecahydro‐3‐hydroxy‐2a,5a,6a,7‐tetramethyl‐5‐(3‐methylbut‐2‐enoyloxy)‐2H,3H‐cyclopenta[4′,5′]furo[2′,3′:6,5]benzo[cd]isobenzofuran‐6‐acetate, C32H42O8, was isolated from uncrushed green leaves of Azadirachta indica A. Juss (neem) and has been found to possess antifeedant activity against Spodptera litura. The conformations of the functional groups are similar to those of 3‐desacetylsalannin, which was isolated from neem kernels. The molecules are linked into chains by intermolecular O—H?O hydrogen bonds. 相似文献
The factor group analysis and the hyperpolarizability study were carried out for the L-asparaginium picrate (LASP) single crystals to explore the possible vibrational modes and the microscopic nonlinearity by the density functional triply parameter hybrid model DFT/B3LYP using GAUSSIAN 98W, respectively. The HF/6-31G (d,p) basis set has been employed. The calculated first order hyperpolarizability of LASP is 4.815 x 10(-29)esu. The Fourier transform infrared (FTIR) spectroscopic studies were performed for identifying different functional groups present in the compound. 相似文献
Reaction of 6-Methyl-2-pyridylacetone, propionone and 2-phenacylpyridine with ethyl ethoxymethylene malonate yield the expected 4-quinolizone derivatives whereas reaction with β-ethoxy--nitroacrylic ester yields indolizine derivatives with the loss of the nitro group. 相似文献
Anatase TiO2 thin films with high optical modulation, better reversibility, fast switching time, and enhanced coloration efficiency were prepared by nebulized spray pyrolysis technique. X-ray diffraction study confirmed the formation of anatase phase TiO2 in the present work. This inference was substantiated from the Raman active modes of A1g, 2 B1g, and 3 Eg corresponding to O–Ti–O bond in TiO2. The PL emission peak observed at 400 nm is corresponds to the indirect transition (X1b?→?Γ3) from the conduction band to the valence band. The average reflectance of TiO2 thin films was varied from 31 to 20%. The electrochemical study revealed the excellent performance of TiO2 films with high optical modulation (ΔT?=?61%), fast switching kinetics (tb?=?1.6 s, tc?=?2.4 s), good coloration efficiency (100 cm2 C?1), and better reversibility (86%). The efficient electrochromic behavior of films may be due to the smooth microstructure nature, which provides an easy pathway for the diffusion and charge transfer process of Li+ ions in TiO2 film matrix. The fast transfer of Li+ ion was realized from the electrochemical impedance spectroscopic measurement. 相似文献
A new organic crystal of semicarbazone of 2–amino–5–chloro–benzophenone has been grown as a single crystal by slow evaporation solution growth technique for the first time in the literature. The grown crystal has been characterised by proton nuclear magnetic resonance spectral analysis and single crystal and powder X-ray diffraction studies. Functional groups of the crystallised molecules were confirmed by FT-IR and FT-Raman analyses. Mechanical strength of the crystals was studied by microhardness test. Optical transparency of the grown crystals has been studied by UV-Visible spectra. The second harmonic generation property of the compound was analysed. 相似文献