Synthesis and characterization of Mg–M (M: Al,Fe, Cr) layered double hydroxides and their application in the hydrogenation of benzaldehyde

Layered double hydroxides or hydrotalcite-like compounds with different kinds of metal ions (Mg–Al, Mg–Fe and Mg–Cr) in the brucite-like sheets were prepared by a co-precipitation method with Mg/M³⁺ molar ratio of ~2. The hydrotalcites were characterized by chemical analysis, X-ray diffraction, Fourier transform infrared spectroscopy, temperature programmed reduction, SEM microscopy, and specific surface area measurements. The activity is evaluated for benzaldehyde reaction. The selectivity to benzyl alcohol is always 90 % even though benzaldehyde conversion depends on the nature of the metal active phase and reaction conditions.     

Catalytic Synthesis of Fused 1,4-Dihydropyridines and 1,4-Dihydropyridine Derivatives Using Preyssler Heteropolyacids Catalyst

An efficient and convenient method for the synthesis of 1,4-dihydropyridines from β-dicarbonyl compounds, aldehydes, and ammonium acetate and the synthesis of fused 1,4-dihydropyridines from dimedone in the presence of Preyssler heteropolyacid catalyst are reported under reflux conditions with good to excellent yields. Preyssler heteropolyacid catalyst is easily prepared, stable (up to 300 °C), reusable, efficient, green and inexpensive.     

Solution studies of triorganotelluronium salts

Evidence for telluronium ylid formation via the salt method is obtained for Ph₂Te(CH₂COPh)Br, but generally telluronium salts (aryl)₂Te(CH₂R)X rapidly dissociate in chloroform solution to (aryl)₂Te and RCH₂X. The relative rates of dissociation of Ph₂(CH₃)TeX in CHCl₃ are: X = I > Br ～ NCS > Cl > PhCOO. Conductivity and ¹H NMR data suggest the salts Ph₂(CH₃)TeX to be covalent and at least dimeric in CHCl₃, but more ionic in DMSO and, to a lesser extent, a DMF. IR data indicate association in solid Ph₂(CH₃)Tel. Kinetic data show that the reaction of CH₃I with excess Ph₂Te (solvent) affords an equilibrium mixture of ionic and covalent forms of Ph₂(CH₃)Tel, the ionic species being formed via the covalent one. Spin trapping experiments with phenyl(t-butyl)nitrone indicate that oxidative addition of alkyl halides to Ph₂Te and redcutive elimination of CH₃SCN from Ph₂ (CH₃)Te(NCS) proceed via radical pathways. A mechanism is proposed for oxidative addition which involves the preformation of a charge transfer complex of RX (alkyl halide) and diphenyltelluride.     

Chemical composition and antibacterial activity of essential oil of Nepeta graciliflora Benth. (Lamiaceae)

The chemical composition of the essential oil obtained from aerial parts of Nepeta graciliflora was analysed, for the first time, by GC–FID and GC–MS. A total of 27 compounds were identified, constituting over 91.44% of oil composition. The oil was strongly characterised by sesquiterpenes (86.72%), with β-sesquiphellandrene (28.75%), caryophyllene oxide (12.15%), α-bisabolol (8.97%), α-bergamotene (8.51%), β-bisabolene (6.33%) and β-Caryophyllene (5.34%) as the main constituents. The in vitro activity of the essential oil was determined against four micro-organisms in comparison with chloramphenicol by the agar well diffusion and broth dilution method. The oil exhibited good activity against all tested organisms.     

A Molecular Tetrahedral Cobalt–Seleno-Based Complex as an Efficient Electrocatalyst for Water Splitting

The cobalt–seleno-based coordination complex, [Co{(SePⁱPr₂)₂N}₂], is reported with respect to its catalytic activity in oxygen evolution and hydrogen evolution reactions (OER and HER, respectively) in alkaline solutions. An overpotential of 320 and 630 mV was required to achieve 10 mA cm⁻² for OER and HER, respectively. The overpotential for OER of this CoSe₄-containing complex is one of the lowest that has been observed until now for molecular cobalt(II) systems, under the reported conditions. In addition, this cobalt–seleno-based complex exhibits a high mass activity (14.15 A g⁻¹) and a much higher turn-over frequency (TOF) value (0.032 s⁻¹) at an overpotential of 300 mV. These observations confirm analogous ones already reported in the literature pertaining to the potential of molecular cobalt–seleno systems as efficient OER electrocatalysts.     

Improvement of Seed Germination Rate,Agronomic Traits,Enzymatic Activity and Nutritional Composition of Bread Wheat (Triticum aestivum) Using Low-Frequency Glow Discharge Plasma

Plasma Chemistry and Plasma Processing - Plasma agriculture is an emerging field. In this report, we studied the effect of medium pressure (~?10 torr) low-frequency...     

Families of univariate and bivariate subdivision schemes originated from quartic B-spline

Families of parameter dependent univariate and bivariate subdivision schemes are presented in this paper. These families are new variants of the Lane-Riesenfeld algorithm. So the subdivision algorithms consist of both refining and smoothing steps. In refining step, we use the quartic B-spline based subdivision schemes. In smoothing step, we average the adjacent points. The bivariate schemes are the non-tensor product version of our univariate schemes. Moreover, for odd and even number of smoothing steps, we get the primal and dual schemes respectively. Higher regularity of the schemes can be achieved by increasing the number of smoothing steps. These schemes can be nicely generalized to contain local shape parameters that allow the user to adjust locally the shape of the limit curve/surface.     

A New Indole Alkaloid from Cleome droserifolia

The phytochemical investigations on Cleome droserifolia resulted in the isolation and characterization of a new indole alkaloid, 5‐hydroxy‐2‐methoxy‐1‐methyl‐1H‐indole‐3‐carbaldehyde ( 1 ). The structure elucidation was carried out on the basis of 1D‐ and 2D‐NMR techniques. In addition to 1 , two known aromatic derivatives, veratrol ( 2 ) and 2‐methoxy‐4‐methylacetophenone ( 3 ), were also obtained. All these compounds were purified by repeated column chromatography of the CH₂Cl₂ fraction obtained from MeOH extract of Cleome droserifolia. The structure of the new compound 1 was finally confirmed by the combined 1D (¹H‐ and ¹³C‐) and 2D (H? C correlations; HMBC and HSQC) NMR and IR spectroscopy, mass spectrometry (MS), and UV absorption spectroscopy techniques. The comparison of the physical and spectroscopic data with those in the literature provided evidence for the structure confirmation of known compounds. All the purified compounds were subjected to urease and α‐glucosidase enzymes inhibition. The results showed that compound 1 was more potent with an IC₅₀ value 11.97±2.067 μg/ml towards urease inhibition, while the activity of α‐glucosidase enzyme was marginal.     

Synthesis of substituted 1,4-diazepines and 1,5-benzodiazepines using an efficient heteropolyacid-catalyzed procedure

An efficient and improved procedure for the synthesis of 1,4-diazepine and 1,5-benzodiazepine derivatives via the reaction of ketimine intermediates with aldehydes in the presence of Keggin-type heteropolyacids (HPAs) was developed. High yields and short reaction times were obtained for both electron-releasing and electron-withdrawing substituted 1,4-diazepine and 1,5-benzodiazepines derivatives.