Electro-Oxidative Selective Esterification of Methylarenes and Benzaldehydes

A mild and green electro-oxidative protocol to construct aromatic esters from methylarenes and alcohols is herein reported. Importantly, the reaction is free of metals, chemical oxidants, bases, acids, and operates at room temperature. Moreover, the design of the electrolyte was found critical for the oxidation state and structure of the coupling products, a rarely documented effect. This electro-oxidative coupling process also displays exceptional tolerance of many fragile easily oxidized functional groups such as hydroxy, aldehyde, olefin, alkyne, as well as neighboring benzylic positions. The enantiomeric enrichment of some chiral alcohols is moreover preserved during this electro-oxidative coupling reaction, making it overall a promising synthetic tool.     

Hexacyanoferrate‐based ionic liquids as Fenton‐like catalysts for deep oxidative desulfurization of fuels

Two hexacyanoferrate‐based ionic liquids, [C₄Py]₃Fe(CN)₆ and [C₁₆Py]₃Fe(CN)₆, were synthesized and characterized using Fourier transform infrared and mass spectroscopies and CHN analysis. They were employed as Fenton‐like catalysts in extraction and catalytic oxidative desulfurization of model oil with dibenzothiophene (DBT), benzothiophene (BT), 4,6‐dimethyldibenzothiophene (4,6‐DMDBT), 4‐methyldibenzothiophene (4‐MDBT) and 3‐methylbenzothiophene (3‐MBT) as substrates. Various polar solvents, such as ionic liquids, water and organic solvents, were applied to choose a suitable extractant. The results showed the removal of DBT reached 97.1% with [C₄Py]₃Fe(CN)₆ as a catalyst and 1‐n‐octyl‐3‐methylimidazolium hexafluorophosphate ([C₈mim]PF₆) as an extractant under optimal conditions. The activity of sulfur removal followed the order DBT > 3‐MBT > BT > 4‐MDBT >4,6‐DMDBT. The effect of water content on sulfur removal was investigated by adding various concentrations of H₂O₂. It was found that excess water had a positive effect on sulfur removal but the catalysts were less sensitive than [FeCl₄^?]‐based catalysts to water. The mechanism was studied using electron spin‐resonance spectroscopy and gas chromatography–mass spectrometry. O₂^?? may be the active oxygen species in the catalytic oxidative desulfurization process and the oxidation products of various sulfur compounds were the corresponding sulfoxides and sulfones. Copyright © 2016 John Wiley & Sons, Ltd.     

A UPLC‐TOF/MS‐based metabolomics study of rattan stems of Schisandra chinensis effects on Alzheimer's disease rats model

A UPLC‐TOF/MS‐based metabolomics method was established to explore the therapeutic mechanisms of rattan stems of S. chinensis (SCS) in Alzheimer's disease (AD). Experimental AD model was induced by intra‐hippocampal Aβ_1–42 injection in rats. Cognitive function and oxidative stress condition in brain of AD rats were assessed using Morris water maze tests and antioxidant assays [malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH‐Px)], respectively. UPLC‐TOF/MS combined with multivariate statistical analysis were conducted to study the changes in metabolic networks in serum of rats. The results indicated that the AD model was established successfully and the inducement of Aβ_1–42 caused a decline in spatial learning and memory of rats. The injection of Aβ_1–42 in rat brains significantly elevated the level of MDA, and reduced SOD and GSH‐Px activities. In addition, SCS showed significant anti‐AD effects on model rats. A total of 30 metabolites were finally identified as potential biomarkers of AD and 14 of them had a significant recovery compared with the AD model after SCS administration. Changes in AD metabolite profiling were restored to different levels through the regulation of 13 pathways. This is first report on the use of the UPLC‐TOF/MS‐based serum metabolomics method to investigate therapeutic effects of SCS on AD, and enrich potential biomarkers and metabolic networks of AD.     

Synthesis and characterization of silica-supported Preyssler nano particles and its catalytic activity for photodegradation of methyl orange

Abstract

Heteropolyacid (H₁₄ [NaP₅W₃₀O₁₁₀])/SiO₂ nano particles were synthesized by a micro emulsion technique. The morphology and size of these nano particles were characterized using, transmission electron microscopy and X-ray diffraction. In a designed photo reactor, the photo degradation of methyl orange as common azo dye pollutants in the environment was selected as a test reaction to estimate the catalytic activity of the synthesized nano particles and found to be excellent.     

Anaerobic Degradation of PCB in Soils

Abstract

The anaerobic degradation of PCB in loamy and clayey soils containing indigeneous microflora was studied. The anaerobic conditions were created by an argon atmosphere in the flasks containing soil flooded by a liquid medium with glucose. GC-ECD analysis of soil extracts after 40 day incubation showed, in addition to the concentration changes of the less chlorinated PCB congeners, a significant decrease in the concentration of highly chlorinated congeners in both soils. The results indicate that in both soil types reductive dehalogenation of PCB congeners was encountered.     

Dissipation of the plant growth regulator hexanoic acid 2-(diethylamino) ethyl ester in pakchoi and soil

A rapid and simple method for determining the plant growth regulator hexanoic acid 2-(diethylamino) ethyl ester (DA-6) in pakchoi and soil using gas chromatography-mass spectrometry (GC-MS) has been developed. For this purpose, a single step was used to extract DA-6 with dichloromethane from aqueous-acetone extracts of vegetables and soil. Average recoveries of DA-6 in pakchoi and soil were between 85% and 104% at both spiking levels 0.01 and 0.1 mg kg^?1. Relative standard deviations (RSD) were less than 11% for all of the recovery tests. The degradation of DA-6 in pakchoi and soil was studied. The results showed that DA-6 degradation in pakchoi and soil coincided with C = 3.9903 e^{?0.0516 t} , C = 0.3476 e^{?0.0224 t} , respectively; the half-lives were 13.43 h and 30.94 h in pakchoi and soil in Beijing, respectively.     

Efficient alkyne homocoupling catalysed by copper immobilized on functionalized silica

Copper immobilized on a functionalized silica support is a good catalyst for the homocoupling of terminal alkynes. The so‐called Glaser–Hay coupling reaction can be run in air with catalytic amounts of base. The copper catalyst is active for multiple substituted alkynes, in both polar and non‐polar solvents, with good to excellent yields (75–95%). Depending on the alkyne, full conversion can be achieved within 3–24 h. The catalyst was characterized by TGA, inductively coupled plasma and X‐ray photoelectron spectroscopy. Leaching tests confirm that the catalyst is and remains heterogeneous. Importantly, the overall reaction requires only alkyne and oxygen (in this case, air) as reagents, making this a clean catalytic oxidative coupling reaction. Copyright © 2012 John Wiley & Sons, Ltd.