<Emphasis Type="Italic">o</Emphasis>-Phenylenediamine as a New Catalyst in the Highly Regioselective Conversion of Epoxides to Halohydrins with Elemental Halogens

Summary. The regioselective ring opening of epoxides using elemental iodine and bromine in the presence of o-phenylenediamine as a new catalyst affords vicinal iodo alcohols and bromo alcohols in high yields. The major advantages of this method are versatility, high regioselectivity, a cheap and commercially available catalyst, mild and neutral reaction conditions, and short reaction times. Fourier transform Raman spectroscopy was used to study the reaction of iodine with o-phenylenediamine. The results indicate that the complex [(Diamine)I]⁺·I₅^– is formed, and we suggest that the major nucleophile is the pentaiodide ion. This bulky nucleophile has a fundamental role in the high regioselectivity observed attacking the less sterically hindered epoxide carbon.     

An investigation of Forex market efficiency based on detrended fluctuation analysis: A case study for Iran

The efficient market hypothesis (EMH) states that asset prices fully reflect all available information. As a result, speculators cannot predict the future behavior of asset prices and earn excess profits at least after adjusting for risk. Although initial tests of the EMH were performed on stock market data, the EMH was soon applied to other markets including foreign exchange (FX). This study uses the detrended fluctuation analysis (DFA) technique to test 01:12:2005–18:04:2010 Iranian Rial/US Dollar exchange rate time series data to see if it can be explained by the weak form of the EMH. Moreover, to determine changes in the degree of inefficiency over time, the whole period has been divided into four subperiods. The study shows that the Iranian Forex market (the Rial/Dollar case) is weak-form inefficient over the whole period and in each of the subperiods. However, the degree of inefficiency is not constant over time. The findings suggest that profitable risk-adjusted trades could be made using past data.     

Synthesis and Characterization of Two Novel Complexes of Cr(III) with Benzilmonoxime

The reaction of benzilmonoxime (BMOH) with CrCl₃.6H₂O in methanol gives the mono nuclear Cr(III) complex, [Cr(BMO)3₃ ( 1 ). Reaction of complex 1 with a methanolic solution of KOH at room temperature leads to a di‐nuclear Cr(III)‐Cr(III) complex, [Cr(BMO)₂(OH)]₂ ( 2 ). The complexes were characterized on the basis of their elemental analysis, Mass, IR, ¹H and ¹³C‐NMR and electronic spectra. The IR studies were useful in assigning the coordination mode of the benzilmonoxime ligand to the chromium(III) ion. In addition, the presence of a hydroxo bridge in the dimeric complex 2 is inferred from the IR spectral studies. The electronic spectra of the complexes revealed two bands due to d–d transitions, and one band assignable to an oxygen (p_π)→Cr(eg*) LMCT transition observed in both complexes. An additional charge transfer transition, assignable to μ‐OH(p_π)→Cr(eg*), was only observed for the dimeric complex 2 . The splitting energy and Racah parameter were calculated to be 18484 cm^‐1 and 560 cm^‐1 for [Cr(BMO)₃] ( 1 ), 17986 cm^‐1 and 545 cm^‐1 for [Cr(BMO)₂(OH)]₂ ( 2 ) respectively.     

Nanocrystalline TiO2, via green combustion synthesis,as an efficient and reusable catalyst for the preparation of 1,8‐dioxooctahydroxanthenes and 1,8‐dioxodecahydroacridines

Nanocrystalline TiO₂ is synthesized using a green combustion method and used as a recyclable catalyst for the one‐pot multicomponent synthesis of 1,8‐dioxodecahydroacridines and 1,8‐dioxooctahydroxanthenes, under solvent‐free conditions. This method is mild, environmentally friendly, inexpensive and highly effective for obtaining good to excellent yields of the products. Copyright © 2015 John Wiley & Sons, Ltd.     

Gallic acid-functionalized magnetic nanoparticles: a convenient and green approach for synthesis of α-aminonitriles under solvent-free conditions

Research on Chemical Intermediates - Gallic acid-coated magnetic nanoparticles were efficiently prepared, characterized by Fourier transform infrared spectroscopy, X-ray diffraction, vibrating...     

Effect of surface polarity on wettability and friction coefficient of silicone rubber/poly(acrylic acid) hydrogel composite

Water absorption, surface energetic, and friction coefficient of filled silicone rubber composites containing different amounts of a superadsorbent hydrogel, poly(acrylic acid) (PAA), were investigated. Measurements were performed in two different time windows, 1 and 5 weeks, to study the effect of hydration time on surface polarity of the samples. It was shown that water absorption increased consistently with hydrogel content and that prolongation of hydration time led to a marked increase in surface tension and polarity. Friction, as measured by a solid–solid contact method in phosphate buffer saline, showed strong dependence on polarity of the composite surface. Results demonstrate that the surface of the composite continued to evolve after the bulk had reached equilibrium swelling and the surface tension reached that of PAA after 5 weeks of hydration time.     

Monte Carlo Simulation of Degradation of Porous Poly(lactide) Scaffolds, 1

Summary: Monte Carlo method was used to simulate the degradation of porous PLA scaffolds. The simulated volume was assumed to be divided homogeneously between the pore and solid PLA with the ratio equal to the bulk porosity of the scaffold. The volume was divided into surface and bulk elements where the surface elements were in direct contact with the aqueous degradation medium, while the bulk elements were surrounded by the pore and solid PLA. The effect of degradation time on PLA ester groups and carboxylic acid end‐groups for surface and bulk elements, pH, PLA degradation rate and mass loss, and PLA molecular weight distribution was simulated. For surface elements, pH remained constant at 7.4 over the entire time of degradation, while for bulk elements its value decreased significantly to as low as 5.8. The highest drop in pH within the scaffold was observed for the highest porosity of 90%. There was a lag time of at least 7 weeks in the mass loss for surface as well as bulk elements for porosities ranging from 70 to 90%. The mass loss for bulk elements was considerably faster than the surface elements. This difference in the rate of mass loss between the surface and bulk elements could affect the 3D morphology and dimensional stability of the scaffold in vivo as degradation proceeds. The simulation predicts that, due to differences in the rate of bulk and surface degradation, hollow structures could form inside the scaffold after 19, 17, and 15 weeks for initial porosities of 70, 80, and 90%, respectively.

A schematic diagram illustrating the degradation of an element on the outer surface of the scaffold (surface element) versus an element within the volume of the scaffold (bulk element).