A Facile and Alternative Method for the Synthesis of Mefloquine

A convenient and facile synthesis of Meflo-quine, based on sulphoxide-Grignard approach is described.

     

Oxidative Deoximation with Sodium Perborate1

An efficient and convenient conversion of oximes to corresponding carbonyl compounds with sodium perborate in glacial acetic acid is reported.     

Spectral and electrochemical investigation of p-sulfonatocalix[4]arene-stabilized vitamin E aggregation

The host–guest interaction of α-tocopherol (vitamin E) with p-sulfonatocalix[4]arene (p-SC4) in solution state is studied using emission and cyclic voltammetric techniques. The lipid soluble α-tocopherol (α-T) forms a solid complex with p-SC4. FTIR and NMR spectral analysis of the solid complex reveals the tight packing of α-T inside the cavity of p-SC4. The structural deformation is confirmed by XRD analysis. SEM images differentiate the highly porous gel like structure of vitamin E aggregate and the solid structure of the host–guest complex prepared. NOESY spectra confirm the tight penetration of α-T within the hydrophobic cavity of p-SC4.     

DC-DC电源的设计考虑:在成本、尺寸和性能之间取得平衡

任何电源设计都要对尺寸、成本和性能进行平衡。任何新项目的第一步都是按这三个参数的重要性对其进行排序,作为设计过程的总指导方针。然而,这里面的成本还包括产品的设计成本——其中包括产品销售(COGS)和设计工作的成本。富有经验的设计人员的工作效率更高,因为他们熟悉设计过程、拓扑结构、元器件和潜在的设计困难,还能够判断在什么时候和什么情况下进行额外的设计和定制才值得。     

Synthesis of a Novel Dispiroheterocyclic Framework via the Regioselective 1,3‐Dipolar Cycloaddition Reaction of Azomethine Ylides

2‐Arylidene‐1,3‐indanediones undergo regioselective 1,3‐dipolar cycloaddition with the azomethine ylide generated from acenaphthenequinone and sarcosine to afford a rare class of complex dispiropyrrolidines in good yield. Single‐crystal X‐ray crystal analysis of one of the products confirms the structure and regiochemistry of the cycloaddition.     

Chemometric and trend analysis of water quality of the South Chennai lakes: an integrated environmental study

In order to bring out the nature of the factors influencing lake water composition, multivariate statistical analysis and trend analysis were performed based on the hydrochemical data of the study area, namely, South Chennai. Change in land use pattern and settlements along the banks of the lakes alters the quality and quantity of the surface water. In the present study, the R‐mode factor analysis and cluster analysis were applied to the geochemical parameters of the water to identify the factors affecting the chemical composition of the lake water. Dendograms of both the seasons give three major clusters, reflecting the groups of unpolluted to moderately polluted, polluted, and heavily polluted stations. The movement of stations from one cluster to another clearly brings out the seasonal variation in the chemical composition of the lake water. The complex hydrochemical data of the surface water were interpreted by condensing them into three major factors. Factor score analysis was used successfully to delineate the stations under study and the role of the contributing factors, and the nature of factors responsible for the variation in chemical composition of the water has been clearly brought out. Results of trend analysis using ArcGIS clearly indicate that the trend in water quality is deteriorating at a faster rate in the eastern part of the study area. It is understood that although natural shifts probably can account for some of the variation, it is most likely that human activities play a major role in affecting the water quality on a regional scale. Copyright © 2014 John Wiley & Sons, Ltd.     

The Synthesis and Bioactivity of Dimethyl (2,3- Dihydrobenzo[b][1,4]Dioxin-6-Yl)(Aryl Amino)Methylphosphonates

Abstract

A new series of α-aminophosphonates have been synthesized by a one-pot three-component reaction of 2,3-dihydrobenzo[b][1,4]dioxine-6-carbaldehyde, various amines, and dimethyl phosphite by using nano-TiO₂ as a catalyst under solvent-free conditions at 50°C. The major advantages of the present method are high yields, short reaction times, recyclable catalyst, and solvent-free reaction conditions. Among these new structurally diversified set of α-aminophosphonates, dimethyl (2,3-dihydrobenzo[b][1,4]dioxin-6-yl)(3-nitrophenylamino) methylphosphonate and dimethyl (2,3-dihydrobenzo[b][1,4]dioxin-6-yl)(4-fluoro-3-nitro-phenyl-amino) methylphosphonate have shown higher antioxidant activity in diphenyl picryl hydrazyl (DPPH) scavenging, reducing power assay, and lipid peroxidation methods.     

Synthesis and Bioassay of Ethyl-2- (2-((Diethoxyphosphoryl) (Aryl) Methylamino)Thiazol-4-Yl)-2-(Methoxyimino)Acetates

Abstract

A simple, efficient, and environmentally benign methodology has been accomplished for the synthesis of α-aminophosphonates by one-pot three-component reaction of ethyl-2-amino-α-(methoxy-imino)-4-thiazoleacetate, aldehydes, and diethylphosphite by using Amberlyst-15 as catalyst at room temperature under solvent-free conditions. Their chemical structures were characterized by infrared (IR), NMR (¹H, ¹³C & ³¹P), mass spectral, and elemental analysis. All the title compounds were screened for radical-scavenging activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH), nitic oxide (NO), and hydrogen peroxide (H₂O₂) methods.

Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional text and figures.     

Detection of dopamine in the presence of excess ascorbic acid at physiological concentrations through redox cycling at an unmodified microelectrode array

The electrochemical behavior of dopamine was examined under redox cycling conditions in the presence and absence of a high concentration of the interferent ascorbic acid at a coplanar, microelectrode array where the area of the generator electrodes was larger than that of the collector electrodes. Redox cycling converts a redox species between its oxidized and reduced forms by application of suitable potentials on a set of closely located generator and collector electrodes. It allows signal amplification and discrimination between species that undergo reversible and irreversible electron transfer. Microfabrication was used to produce 18 individually addressable, 4-μm-wide gold band electrodes, 2 mm long, contained in an array having an interelectrode spacing of 4 μm. Because the array electrodes are individually addressable, each can be selectively biased to produce an overall optimal electrochemical response. Four adjacent microbands were shorted together to serve as the collector, and were flanked on each side by seven microbands shorted as the generator (a ratio of 1:3.5 of electroactive area, respectively). This configuration achieved a detection limit of 0.454?±?0.026 μM dopamine at the collector in the presence of 100 μM ascorbic acid in artificial cerebrospinal fluid buffer, concentrations that are consistent with physiological levels. Enhancement by surface modification of the microelectrode array to achieve this detection limit was unnecessary. The results suggest that the redox cycling method may be suitable for in vivo quantification of transients and basal levels of dopamine in the brain without background subtraction.