Cobalt manganese oxide nanoparticles as recyclable catalyst for efficient synthesis of 2‐aryl‐1‐arylmethyl‐1H‐1,3‐benzimidazoles under solvent‐free conditions

Cobalt manganese oxide nanocatalyst was synthesized and it was found that it is a highly efficient green catalyst for the synthesis of 2‐aryl‐1‐arylmethyl‐1H‐1,3‐benzimidazoles under solvent‐free conditions. The marked advantages of this method are the simple experimental procedures, shorter reaction times, high yields of product, reusable and non‐toxic catalyst and solvent‐free conditions. Copyright © 2015 John Wiley & Sons, Ltd.     

N-Propylsulfamic acid supported onto magnetic Fe3O4 nanoparticles (MNPs-PSA) as a green and reusable heterogeneous nanocatalyst for the chemoselective preparation and deprotection of acylals

Research on Chemical Intermediates - N-propylsulfamic acid supported onto magnetic Fe3O4 nanoparticles (MNPs-PSA) was simply synthesized and used as a highly efficient, environmentally friendly,...     

Solvent-free acetylation and tetrahydropyranylation of alcohols catalyzed by recyclable sulfonated ordered nanostructured carbon

Rapid and practical green acetylation and tetrahydropyranylation routes of structurally diverse alcohols and phenols were applied under solvent-free reaction conditions providing excellent yields, using catalytic amounts of environmentally friendly sulfonated ordered nanoporous carbon (CMK-5-SO₃H). Non-toxic nature of the catalyst, its easy handling, recovery and reusability, and the absence of any solvent characterize the presented procedures as efficient methods. These procedures provide methods for the separation of the product by simple filtration.     

Poly(urethane‐co‐benzoxazine)s via reaction of phenol terminated urethane prepolymers and benzoxazine monomer and investigation of their properties

In the present work, a new method was developed for the combination of polyurethanes (PUs) and polybenzoxazine (PBz) to obtain novel thermoset poly(urethane‐co‐benzoxazine)s with good thermal, mechanical, and electrical properties as well as low temperature curing profile. Knowing the catalytic effect of compounds possessing free phenolic groups on ring opening polymerization of benzoxazine monomers, preparation of phenol terminated urethane oligomers (PTPU) as the macroinitiator for a benzoxazine monomer (Ba) was considered. Firstly, NCO‐terminated urethane prepolymers were prepared from the reaction of poly(tetramethyleneether glycol), and 2,4‐tolylene diisocyanate, and then end functionalized with bisphenol‐A under proper condition. DSC, DMTA, and gel content measurements were applied to find optimum ring opening polymerization condition (170°C for 1 hr and 200°C for 15 min). Various kinds of thermoset polymers were prepared by the reaction of PTPU at different molecular weights with variable contents of Ba. All of monomeric and polymeric materials were characterized by conventional spectroscopic methods and their thermal, mechanical, viscoelastic, and electrical properties were measured and properties were correlated to their structure. Due to the interesting properties of these new materials, the possibility of using them as electrical insulators with higher service temperature in comparison to common PUs were examined and their potential applicability was confirmed. Copyright © 2010 John Wiley & Sons, Ltd.     

Theoretical study of molecular interactions of sulfur ylide with HF, HCN, and HN3

The molecular interactions between sulfur ylide (SY) and HX molecules (X = F, CN, and N₃) were investigated using the MP2 method at 6-311++G(2d,2p) basis set. Three different patterns including non-classical hydrogen bond (HB) H···C and classical HB H···X were found for complex formation between SY and HX molecules. Stability of the H···C type complexes are greater than H···X complexes. Quantum theories of atoms in molecules, natural bond orbitals, and energy decomposition analysis methods have been applied to analyze the intermolecular interactions. Good correlations have been found between the interaction energies (SE), the second-order perturbation energy E ⁽²⁾ and the charge transfer qCT in the studied systems.     

Glucose interaction with Au,Ag, and Cu clusters: Theoretical investigation

Interactions of α‐D ‐glucose with gold, silver, and copper metal clusters are studied theoretically at the density functional theory (CAM‐B3LYP) and MP2 levels of theory, using trimer clusters as simple catalytic models for metal particles as well as investigating the effect of cluster charge by studying the interactions of cationic and anionic gold clusters with glucose. The bonding between α‐D ‐glucose and metal clusters occurs by two major bonding factors; the anchoring of M atoms (M = Cu, Ag, and Au) to the O atoms, and the unconventional M…H? O hydrogen bond. Depending on the charge of metal clusters, each of these bonds contributes significantly to the complexation. Binding energy calculations indicate that the silver cluster has the lowest and gold cluster has the highest affinity to interact with glucose. Natural bond orbital analysis is performed to calculate natural population analysis and charge transfers in the complexes. Quantum theory of atoms in molecules was also applied to interpret the nature of bonds. © 2012 Wiley Periodicals, Inc.     

A Convenient and High Throughput HPTLC Method for Determination of Progesterone in Release Media of Silicon-based Controlled-release Drug-delivery Systems

JPC – Journal of Planar Chromatography – Modern TLC - A simple, rapid, and sensitive high-performance thin-layer chro-matographic method has been developed for determination of...     

Extraction and characterization of native heteroxylans from delignified corn stover and aspen

Dimethylsulfoxide-solubilized polysaccharides from delignified corn stover and aspen were characterized. The biomass was delignified by two different techniques; a standard acid chlorite and a pulp and paper QPD technique comprising chelation (Q), peroxide (P), and acid-chlorite (D). Major polysaccharides in all fractions were diversely substituted xylan. Xylan acetylation was intact after chlorite delignification and, as expected, xylan from QPD-delignified fraction was de-acetylated by the alkaline peroxide step. The study of DMSO-extractable xylans from chlorite-delignified biomass revealed major differences in native acetylation patterns between corn stover and aspen xylan. Xylan from cell walls of corn stover contains 2-O- and 3-O-mono-acetylated xylan and [MeGlcA-α-(1 → 2)][3-OAc]-xylp units. In addition, aspen xylan also contains 2,3-di-O-acetylated xylose. 1,4-β-d-xylp residues substituted with MeGlcA at O-2 position are absent in chlorite-delignified aspen xylan. Sugar composition in accord with NMR-spectroscopic data indicated that corn stover xylan is arabinosylated while aspen xylan is not. We have shown that corn stover xylan has similar structure with xylans from other plants of Poales order. No evidence was found to indicate the presence of 1,4-β-d-[MeGlcA-α-(1 → 2)][Ara-α-(1 → 3)]-xylp in corn stover xylan fractions.     

A two-beam interferometer for dispersive reflection spectroscopy of solids in the far infrared at temperatures between 4 and 300K

A Fourier spectrometer has been developed for determining the optical constants of highly absorbing solids in the far infrared at temperatures down to 4.2K from measurements of their amplitude and phase reflection spectra. The spectrometer has been constructed almost entirely from commercially available components, and its performance is illustrated with measurements of the optical constants of NaCl at 6K.