An efficient synthesis of ferrocenyl imidazo[1,2-a]pyridines

Abstract  

An efficient and simple synthesis of ferrocenyl 3-aminoimidazo[1,2-a]pyridines by the three-component reaction of ferrocenecarboxaldehyde, isocyanides, and 2-aminopyridines in the presence of a catalytic amount of InCl₃ in ethanol at room temperature is reported.     

Electronic properties of bilayer and trilayer graphyne in the presence of electric field

The influence of electric field on the electronic properties of bilayer and trilayer graphyne has been studied using the density functional theory. We have investigated alpha graphyne due to its analogous to graphene. The bilayer and trilayer graphyne with different stacking style configurations have been considered. Our results indicate that the electronic properties of alpha graphyne are insensitive to the number of graphyne layer and configuration. The bilayer and trilayer graphyne are semimetal similar to the monolayer graphyne. It is found that applying a uniform electric field perpendicular to the graphyne sheet changes the electronic properties of AB-stacked bilayer and ABC-stacked trilayer graphyne so that they become semiconductor. The band gaps of the bilayer and trilayer graphyne with these configurations are enhanced by increasing strength of the electric field. Therefore, possibility of controlling the electronic properties of graphyne by applying electric field makes graphyne as a good candidate for next generation nanoelectronic devices.     

Nanocrystalline cellulose acetate (NCCA)/graphene oxide (GO) nanocomposites with enhanced mechanical properties and barrier against water vapor

Highly flexible nanocomposite films of nanocrystalline cellulose acetate (NCCA) and graphene oxide (GO) were synthesized by combining NCCA and GO sheets in a well-controlled manner. By adjusting the GO content, various NCCA/GO nanocomposites with 0.3–1 wt% GO were obtained. Films of these nanocomposites were prepared using the solvent casting method. Microscopic and X-ray diffraction (XRD) measurements demonstrated that the GO nanosheets were uniformly dispersed in the NCCA matrix. Mechanical properties of the composite films were also studied. The best GO composition of the samples tested was 0.8 wt%, giving tensile strength of 157.49 MPa, which represents a 61.92 % enhancement compared with NCCA. On the other hand, the composite films showed improved barrier properties against water vapor. This simple process for preparation of NCCA/GO films is attractive for potential development of high-performance films for electrical and electrochemical applications.     

Hydrogenation of 2,4-Dinitrotoluene to 2,4-Diaminotoluene over Platinum Nanoparticles in a High-Pressure Slurry Reactor

A practical and convenient synthesis of the fungicidal natural compound farinomalein is described starting from readily available ethyl 3-methyl-2-oxobutyrate and triethyl phosphonoacetate, employing a Horner–Wadsworth–Emmons condensation as the key step.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Application of crown ethers as stationary phase in the chromatographic methods

Recently, much attention has been paid to chromatographic characteristics and applications of crown ethers. These compounds were employed as chiral stationary phase for resolution of various racemic compounds in high performance chromatography and capillary electrochromatography techniques. Crown ethers also used in gas chromatography as the stationary phase. Recently, it has been found that, crown ethers also may be useful in cation chromatographic separation in ion chromatography for the determination of alkali and alkaline-earth cations, ammonium, and amines. In this paper we have an overview on these applications of crown ethers.     

Recent developments in microextraction techniques based on crown ethers

Sample preparation is essential for isolating desired components from complex matrices and greatly influences their reliable and accurate analysis. Microextraction techniques such as solid phase micro extraction and liquid–liquid–liquid micro extraction based on hollow fiber and also single drop micro extraction methods are new and effective sample preparation techniques. Crown ethers are heterocyclic chemical compounds that consist of a ring containing several ether groups. Recently crown ethers have been applied in these methods and increase efficiency and selectivity of these techniques. Here we review the application of crown ethers in various micro extraction techniques.     

A nanocomposite made from conducting organic polymers and multi-walled carbon nanotubes for the adsorption and separation of gold(III) ions

We describe a new method for the separation and preconcentration of traces of Au(III) in environmental samples. Sorbents made from modified multiwalled carbon nanotubes and conducting polymers (PANI and PEDOT) were used for solid-phase extraction. The Au(III) ions are adsorbed as a result of the interaction with the electron pairs of =N- and -S- groups. Effects of pH value, flow rate and volume of sample, type, volume and concentration of eluent, and the adsorption capacity were investigated. The maximum adsorption capacity of MWCNTs/PANI and MWCNTs/PEDOT are 159 and 176?mg?g^?1, and the detection limits of this method are below 0.3 and 0.5?ng?mL^?1, respectively. The procedure was successfully applied to the determination of traces of Au(III) in a reference material and in environmental samples.

Application of N-thiocyanatosuccinimide as a reagent for the facile conversion of epoxides into thiocyanohydrines

The use of in situ generated N-thiocyanatosuccinimide with NH₄SCN offers an efficient reagent system for the conversion of epoxides into their corresponding thiocyanohydrines in good to high yields.The major advantages of this method are as follows:use of cheap reagent,high regioselectivity,simple availability of reagent,ease of workup of the reaction.     

Refined Second Law of Thermodynamics for Fast Random Processes

We establish a refined version of the Second Law of Thermodynamics for Langevin stochastic processes describing mesoscopic systems driven by conservative or non-conservative forces and interacting with thermal noise. The refinement is based on the Monge-Kantorovich optimal mass transport and becomes relevant for processes far from quasi-stationary regime. General discussion is illustrated by numerical analysis of the optimal memory erasure protocol for a model for micron-size particle manipulated by optical tweezers.