Copper(II) tetrafluroborate-promoted Meinwald rearrangement reactions of epoxides

Epoxides undergo a highly efficient Meinwald rearrangement in the presence of catalytic quantities of copper(II) tetrafluoroborate to give carbonyl compounds in high yields and with excellent selectivity. The low toxicity and ease of handling of this reagent make it an attractive alternative to the more corrosive or costly Lewis acids frequently employed.     

Surface morphological and impedance spectroscopic studies on the interaction of polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) with mild steel in acid solutions

The inhibition of mild steel corrosion in aerated acid mixture of 0.5 N H₂SO₄ and 0.5 N HCl solution was investigated using potentiodynamic polarization studies, linear polarization studies, electrochemical impedance spectroscopy, adsorption, and surface morphological studies. The effect of inhibitor concentration on corrosion rate, degree of surface coverage, adsorption kinetics, and surface morphology is investigated. The inhibition efficiency increased markedly with increase in additive concentration. The presence of PEG and PVP decreases the double-layer capacitance and increases the charge-transfer resistance. The inhibitor molecules first adsorb on the metal surface following a Langmuir adsorption isotherm. Both PEG and PVP offer good inhibition properties for mild steel and act as mixed-type inhibitors. Surface analysis by scanning electron microscopy (SEM) and atomic force microscopy (AFM) shows that PVP offers better protection than PEG.     

Synthesis and cytotoxicity study of pyrazoline derivatives of methoxy substituted naphthyl chalcones

2-Acetyl naphthalene reacts with various methoxy substituted benzaldehyde in the presence of 10 % sodium hydroxide solution giving functionalized chalcones. The synthesized chalcones when further reacted with hydrazine hydrate in the presence of acetic acid afforded N-acetyl pyrazolines. All the synthesized products were confirmed by various spectral data such as FTIR, ¹H NMR, ¹³C NMR, and HRMS studies. All the synthesized compounds were screened for cytotoxicity against various cell lines.     

Studies on accelerated sulphur vulcanization of natural rubber using 1-phenyl-2, 4-dithiobiuret/tertiary butyl benzothiazole sulphenamide

The use of binary accelerators has gained tremendous importance since it increases the production rate of the article made of that elastomer. The authors have analyzed the performance of a novel binary accelerator system in the sulphur vulcanization of natural rubber (NR). The vulcanizates resulting from the binary accelerated process obtained good mechanical properties, ageing and swelling resistance. Network characterization of the mixes was done using swelling measurements, stress-strain analysis etc. The chain entanglement density was measured using dynamic mechanical analysis. However the performance is found to be dependent on the relative proportion of mono, di and polysulphidic linkages in the material. The result of the study points out that the proposed system can be active in NR regardless of the vulcanization recipe and temperature. The performance of the new binary system in filled vulcanizates is also studied. Based on the processing, mechanical and chemical characterization an optimum concentration is suggested for the new system.     

Antifungal activity of silver nanoparticle-encapsulated β-cyclodextrin against human opportunistic pathogens

Silver nanoparticles were synthesised by reducing silver acetate with a long-chain aliphatic amine. β-Cyclodextrin (CD)-stabilised silver nanoparticles were successfully synthesised and characterised by the UV–vis spectroscopy and scanning electron microscopy analysis. This system was examined for their antifungal activity against opportunistic human pathogens such as Aspergillus fumigatus, Mucor ramosissimus and Chrysosporium species. This study clearly demonstrates that the present system is a powerful antifungal agent against human opportunistic pathogenic fungi.     

Nanostructuring of 1-butyl-4-methylpyridinium chloride in ionic liquid–iron oxide nanofluids

Journal of Thermal Analysis and Calorimetry - Understanding the behavior of ionic liquids (ILs) in ionic liquid-based nanofluids has great significance for its proper application. The phase changes...     

Reduction vs. Addition: The Reaction of an Aluminyl Anion with 1,3,5,7‐Cyclooctatetraene

The potassium aluminyl complex K[Al(NON^Ar)] (NON=NON^Ar=[O(SiMe₂NAr)₂]^2?, Ar=2,6‐iPr₂C₆H₃) reacts with 1,3,5,7‐cyclooctatetraene (COT) to give K[Al(NON^Ar)(COT)]. The COT‐ligand is present in the asymmetric unit as a planar μ₂‐η²:η⁸‐bridge between Al and K, with additional K???π‐aryl interactions to neighboring molecules that generate a helical chain. DFT calculations indicate significant aromatic character, consistent with reduction to [COT]^2?. Addition of 18‐crown‐6 causes a rearrangement of the C₈‐carbocycle to form the isomeric 9‐aluminabicyclo[4.2.1]nona‐2,4,7‐triene anion.     

Generation and EPR Spectroscopy of the First Silenyl Radicals,R2C=Si.−R: Experiment and Theory

The first two persistent silenyl radicals (R₂C=Si^.?R), with a half‐life (t_1/2) of about 30 min, were generated and characterized by electron paramagnetic resonance (EPR) spectroscopy. The large hyperfine coupling constants (hfccs) (a(²⁹Si_α)=137.5–148.0 G) indicate that the unpaired electron has substantial s character. DFT calculations, which are in good agreement with the experimentally observed hfccs, predict a strongly bent structure (?C=Si?R=134.7–140.7°). In contrast, the analogous vinyl radical, R₂C=C^.?R (t_1/2≈3 h), exhibits a small hfcc (a(¹³C_α)=26.6 G) and has a nearly linear geometry (?C=C?R=168.7°).