Selective Styrene Oxidation to Benzaldehyde over Recently Developed Heterogeneous Catalysts

The selective oxidation of styrene under heterogeneous catalyzed conditions delivers environmentally friendly paths for the production of benzaldehyde, an important intermediate for the synthesis of several products. The present review explores heterogeneous catalysts for styrene oxidation using a variety of metal catalysts over the last decade. The use of several classes of supports is discussed, including metal–organic frameworks, zeolites, carbon materials and silicas, among others. The studied catalytic systems propose as most used oxidants tert-butyl hydroperoxide, and hydrogen peroxide and mild reaction conditions. The reaction mechanism proceeds through the generation of an intermediate reactive metal–oxygen species by catalyst-oxidant interactions. Overall, most of the studies highlight the synergetic effects among the metal and support for the activity and selectivity enhancement.     

Effect of Anode Material on Electrochemical Oxidation of Low Molecular Weight Alcohols—A Review

The growing climate crisis inspires one of the greatest challenges of the 21st century—developing novel power sources. One of the concepts that offer clean, non-fossil electricity production is fuel cells, especially when the role of fuel is played by simple organic molecules, such as low molecular weight alcohols. The greatest drawback of this technology is the lack of electrocatalytic materials that would enhance reaction kinetics and good stability under process conditions. Currently, electrodes for direct alcohol fuel cells (DAFCs) are mainly based on platinum, which not only provides a poor reaction rate but also readily deactivates because of poisoning by reaction products. Because of these disadvantages, many researchers have focused on developing novel electrode materials with electrocatalytic properties towards the oxidation of simple alcohols, such as methanol, ethanol, ethylene glycol or propanol. This paper presents the development of electrode materials and addresses future challenges that still need to be overcome before direct alcohol fuel cells can be commercialized.     

Assessment of the Arsenic Removal From Water Using Lanthanum Ferrite

The catalytic performance of a perovskite-type lanthanum ferrite LaFeO₃ to remove arsenic from water has been investigates for the first time. LaFeO₃ was prepared by citrate auto-combustion of dry gel obtained from a solution of the corresponding nitrates poured into citric acid solution. Kinetic studies were performed in the dark with As(V) and in the dark and under UV-C irradiation at pH 6–7 with As(III) (both 1 mg L⁻¹), and As : Fe molar ratios (MR) of 1 : 10 and 1 : 100 using the LaFeO₃ catalyst. As(V) was removed from solution after 60 min in the dark in 7 % and in 47 % for MR=1 : 10 and MR=1 : 100, respectively, indicating the importance of the amount of the iron material on the removal. Oxidation of As(III) in the dark was negligible after 60 min in contact with the solid sample, but complete removal of As(III) was observed within 60 min of irradiation at 254 nm, due to As(III) photooxidation to As(V) and to As(III) sorption to a minor extent. Morphological and microstructural studies of the catalyst complement the catalytic testing. This work demonstrates that LaFeO₃ can be used for the removal of As(III) from highly arsenic contaminated water.     

Aziridine-2-carboxylic acid derivatives and its open-ring isomers as a novel PDIA1 inhibitors

Chemistry of Heterocyclic Compounds - Acyl derivatives of aziridine-2-carboxylic acid have been synthesized and tested as PDIA1 inhibitors. Calculations of charge value and distribution in...     

Determination of gold leaf thickness in a Renaissance illumination using a nondestructive approach

In this work, the thickness of the gold leaf applied in the Manueline foral charter of Murça (illuminated in 1512) will be determined using X‐ray fluorescence. In the frontispiece of the Manueline foral charter of Murça, the capital D was gilded using a gold leaf over a priming made of lead white. The characteristic lines of Pb (namely Lα and Lβ), although attenuated in the Au layer, are still visible in the X‐ray fluorescence spectra. By determining the intensity ratio Lα/Lβ and comparing it with the ratio for an infinitely thick sample, the thickness of the attenuating material can be determined. Using this methodology, the thickness of the gold leaf applied in the charter of Murça was estimated as 1.6 µm. Copyright © 2013 John Wiley & Sons, Ltd.     

Smart photoluminescent nanohybrids based on CdSe quantum dots capped with multidentate thiolated pH‐responsive and thermoresponsive polymers for nanosensing

Well‐defined thermoresponsive polymers obtained by the atom transfer radical polymerization (ATRP) of short oligo(ethylene glycol) methyl ether methacrylates (MEO_nMA, n = 2, 3, or 8) with small ratios of a thiolated comonomer, 2‐(acetylthio)ethylmethacrytale, can replace the hydrophobic trioctylphosphine oxide (TOPO) capping of CdSe quantum dots (QDs). After this facile ligand exchange, the mild hydrolysis of the acetylthiol group into thiol is the key to enhance the QD luminescence. However, the length of the ethylene glycol side chain is critical for the success of the functionalization; it is established that the shortest MEO₂MA‐based copolymers result in a compact coating and a highest quantum yield (up to a factor of 6) when compared with that of CdSe@TOPO in dichloromethane. In addition, the amphiphilic character of the copolymer allows the CdSe@P(MEO_nMA‐co‐SEMA) nanohybrids to disperse in water. On the other hand, the residual ionizable thiol groups do not get attached to the QD surface, cause that the lower critical solubility temperature of the polymer depends on pH as well. Thus, at acidic pH, an abrupt increase in the luminescence emission accompanies the polymer collapse, which establishes the promise of these hybrids as temperature/pH nanosensors and targeted drug delivery. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3087–3095