Reaction of bicyclo[2.2.1]hept‐5‐ene‐endo‐2‐ylmethylamine and nitrophenyl glycidyl ethers

Reactions of 2‐nitro‐, 4‐nitro‐ and 2,4‐dinitrophenylglycidyl ethers with bicyclo[2.2.1]hept‐5‐ene‐endo‐2‐ylmethylamine in isopropanol have been studied. The mixtures of products were chromatographed on silica gel and eluted with ether or ether/2‐propanol (1:1), the structures of individual products have been confirmed by IR spectra, NMR ¹H, ¹³C spectra, using experiments that involve homonuclear and heteronuclear scalar coupling interactions (COSY, TOCSY, HMQC, HMBC), and mass spectrometry. Amino alcohols as the major products of regioselective aminolysis of epoxides (according to the Krasusky rule) have been obtained. The minor products were the compounds with two hydroxyalkyl fragments at the nitrogen atom. In case of dinitrophenylglycidyl ether, it was the minor product of aryl nucleophilic substitution (S_NAr). The abnormal course of aminolysis has been confirmed by the results of quantum‐chemical calculations of activation barries and Free Gibbs energies of the competitive reactions of epoxides (at the B3LYP/6‐311 + G(d,p) level of theory). Copyright © 2010 John Wiley & Sons, Ltd.     

Al2O3 supported Ru catalysts prepared by thermolysis of Ru3(CO)12 for catalytic wet air oxidation

Low loading catalysts Ru/γ-Al₂O₃ and Ru-Ce/γ-Al₂O₃ were prepared by thermolysis of Ru₃(CO)₁₂ on γ-Al₂O_3. The catalysts were characterized by XPS, XRD and SEM. Two new Ru species (Ru_A and Ru_B) were detected during the Ru₃(CO)₁₂ decomposition process due to chemical interaction with the active OH groups on the surface of Al₂O₃ support, and the reduction of them can lead to more dispersed metallic phases. The sample was completely decomposed at 673 K in H₂, and RuO₂ was formed with minor amounts of Ru⁰. When the temperature was increased to 773 K to heat the sample, the ratio of Ru⁰ to RuO₂ increased. However, after the addition of CeO₂, only RuO₂ was detected on surface. The catalysts exhibited high activities in Catalytic Wet Air Oxidation (CWAO) of different organic compounds at high concentration such as isopropyl alcohol, phenol, acetic acids and N,N-dimethylformamide, which is attributed to the better dispersion of Ru particles and the addition of CeO₂ further enhanced number of effectively active sites on the cluster-derived catalyst surface.     

Synthesis and characterization of magnetic diphase ZnFe(2)O(4) /γ-Fe(2)O(3) electrospun fibers

Magnetic nanofibers of ZnFe₂O₄/γ-Fe₂O₃ composite were synthesized by electrospinning from a sol-gel solution containing a molar ratio (Fe/Zn) of 3. The effects of the calcination temperature on phase composition, particle size and magnetic properties have been investigated. Zinc ferrite fibers were obtained by calcinating the electrospun fibers in air from 300 to 800 °C and characterized by thermogravimetric analyses, Fourier transformed infrared spectroscopy, X-ray photoemission spectroscopy, X-ray diffraction, vibration sample magnetometry and magnetic force microscopy. The resulting fibers, with diameters ranging from 90 to 150 nm, were ferrimagnetic with high saturation magnetization as compared to bulk. An increase in the calcination temperature resulted in an increase in particle size and saturation magnetization. The observed increase in saturation magnetization was most likely due to the formation and growth of ZnFe₂O₄/γ-Fe₂O₃ diphase crystals. The highest saturation magnetization (45 emu/g) was obtained for fibers calcined at 800 °C.     

Effect of Silk Fibroin Reinforcement on the Properties of Potato Starch-Polyvinyl Alcohol Blend Films

Starch and polyvinyl alcohol composite films, reinforced with raw and methylmethacrylate-grafted silk fibroin particles, were prepared by the solution-casting method on leveled plates. Silk fibroin was used as reinforcement for starch and polyvinyl alcohol (St/PVA) blends in order to improve their mechanical and water-resistance properties. The composites were plasticized with citric acid and cross-linked with gluteraldehyde. The reinforced films showed an increase in tensile strength with decrease in elongation at break. The optimized samples were characterized by scanning electron microscopy and were studied for their antibacterial properties. The biodegradable behavior was studied by the soil burial method.     

Palladium‐Catalyzed Allylic Alkylation of Simple Ketones with Allylic Alcohols and Its Mechanistic Study

Allylic alcohols were directly used in Pd‐catalyzed allylic alkylations of simple ketones under mild reaction conditions. The reaction proceeded smoothly at 20 °C by the concerted action of a Pd catalyst, a pyrrolidine co‐catalyst, and a hydrogen‐bonding solvent, and does not require any additional reagents. A computational study suggested that methanol plays a crucial role in the formation of the π‐allylpalladium complex by lowering the activation barrier.     

Synthesis and biocidal activity of modified poly(vinyl alcohol)

Functionalized polymers and their polymer nature give them more advantages than the corresponding small molecules. In this respect, polymeric ammonium and phosphonium salts were prepared by chemical modifications of poly(vinyl alcohol) (PVA) aiming to explore their antimicrobial activities against pathogenic bacteria and fungi. The modifications were performed by chloroacetylation with chloroacetyl chloride. Incorporation of the ammonium and phosphonium salts was conducted by the reaction of chloroacetylated poly(vinyl alcohol) (CPVA) with triethylamine (TEA), triphenylphosphine (TPP), and tributylphosphine (TBP). The antimicrobial activity of the polymers against variety of test microorganisms was examined by the cut plug and viable cell counting methods of shake cultures of 10 times dilute nutrient broth and Sabouraud^’s media, seeded with the test microorganisms. It was found that the immobilized polymers exhibited antimicrobial activity against the Gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Shigella sp. and Salmonella typhi) and Gram positive bacteria (Bacillus subtilis and B. cereus) and the dermatophyte fungus (Trichophyton rubrum). The growth inhibition of the test microorganisms (ratio of surviving cell number, M/C) varied according to the composition of the active group in the polymer and the test organism. It increased by increasing the concentration of the polymer. Triphenyl phosphonium salt of the modified poly(vinyl alcohol) exhibited the most biocidal activity against both Gram-negative and Gram-positive bacteria after 24 h.     

Gold & silver nanoparticles supported on manganese oxide: Synthesis,characterization and catalytic studies for selective oxidation of benzyl alcohol

Nano-gold and silver particles supported on manganese oxide were synthesized by the co-precipitation method. The catalytic properties of these materials were investigated for the oxidation of benzyl alcohol using molecular oxygen as a source of oxygen. The catalyst was calcined at 300, 400 and 500 °C. They were characterized by electron microscopy, powder X-ray diffraction (XRD) and surface area. It was observed that the calcination temperature affects the size of the nanoparticle, which plays a significant role in the catalytic process. The catalyst calcined at 400 °C, gave a 100% conversion and >99% selectivity, whereas catalysts calcined at 300 and 500 °C gave a conversion of 69.51% and 19.90% respectively, although the selectivity remains >99%.     

Application of carbon-based nanomaterials in sample preparation: A review

In this paper, a broad overview on the applications of different carbon-based nanomaterials, including nanodiamonds, fullerenes, carbon nanotubes, graphene, carbon nanofibers, carbon nanocones-disks and nanohorns, as well as their functionalized forms, in sample preparation is provided. Particular attention has been paid to graphene because many papers regarding its application in this research field are becoming available. The distinctive properties, derivatization methods and application techniques of these materials were summarized and compared. According to their research status and perspective, these nanomaterials were classified in four groups (I: graphene and carbon nanotubes; II: carbon nanofibers; III: fullerenes; and IV: nanodiamonds, carbon nanocones/disks and carbon nanohorns) and characteristics and future trends of every group were discussed.     

Efficient Oxidation of Benzylic Alcohols with Trichloroisocyanuric Acid and Ionic Liquid in Water

Studies on the stereoselective synthesis of a pyrrolidinoisoquinoline derivative using acyliminium ion cyclization of hydroxylactams are described. Cyclization reaction of chiral hydroxylactams 2a～c, derived from (L)-tartaric acid and phenethylamine, afforded one diastereomer 3 under a variety of acidic conditions in moderate to good yields.