Synthesis of symmetrical and unsymmetrical 3,3-di(indolyl)indolin-2-ones under controlled catalysis of ionic liquids

Three ionic liquids, [BMIM][BF₄] doped with 60 mol % of LiCl ([BMIM][BF₄]-LiCl), N,N,N,N-tetramethylguanidinium trifluoroacetate (TMGT), and N,N,N,N-tetramethylguanidinium triflate (TMGT_f) were found useful as catalyst solvents for controlled 3-indolylation of isatins. Our investigation revealed that the reaction between isatin and indoles in [BMIM][BF₄]-LiCl or TMGT_f media stops at the step of addition of the two components providing 3-indolyl-3-hydroxyindolin-2-ones while the ionic liquid TMGT runs the reaction further through accompanying Friedel-Crafts substitution to afford symmetrical 3,3-di(indol-3-yl)indolin-2-ones. To take advantage of the difference between the effects of these ionic liquids on the reaction progress, we planned a two-step protocol for the efficient synthesis of unsymmetrical 3,3-di(indol-3-yl)indolin-2-ones.     

Analytical Formulation for ϕ 4 Field Potential Dynamics

An analytical model for adding a space-dependent potential to the ? ⁴ field equation of motion is presented, by constructing a collective coordinate system for the solitary solutions of this model. The interaction of ? ⁴ solitons with a delta function potential barrier and also delta function potential well is investigated. Most of the characters of interaction are derived analytically while they are calculated by other models numerically. We will find that the behaviour of a solitary solution is like a point particle which is moved under the influence of a complicated effective potential. The effective potential is a function of the field initial conditions and also of parameters of the added potential.     

Ambient synthesis of spiro[4H-pyran-oxindole] derivatives under [BMIm]BF4 catalysis

A simple and efficient one-pot approach for assembling some fused spiro[4H-pyran-oxindole] heterocycles by means of three-component reactions between isatins, malononitrile or ethyl cyano-acetate, and 1,3-dicarbonyl compounds is reported. The combinatorial syntheses were achieved for the first time without applying extra activation energy at ambient temperature while making use of [BMIm]BF₄ as an ionic liquid catalyst. Good functional group tolerance and broad scope of usable substrates are other prominent features of the present methodology.     

Collective-Coordinate Analysis of Inhomogeneous Nonlinear Klein–Gordon Field Theory

Two different sets of collective-coordinate equations for solitary solutions of nonlinear Klein–Gordon (NKG) model are introduced. The collective-coordinate equations are derived using different approaches for adding the inhomogeneities as external potentials to the soliton equation of motion. The interaction of the NKG field with a local inhomogeneity like a delta function potential wall or a delta-function potential well is investigated using the presented collective-coordinate equations, and the results of the two different models are compared. Most of the characters of the interaction are derived analytically. The analytical results are also compared to the results of numerical simulations.     

Numerical prediction of humidification process in planar porous membrane humidifier of a PEM fuel cell system to evaluate the effects of operating and geometrical parameters

In present study, a numerical model is employed to investigate the effects of different operating parameters and channel geometry on the performance of membrane humidifier. Simulations are performed by a commercial CFD code and based on user defined functions. Three-dimensional counter-flow humidifier model for a gas-to-gas case is considered. Results show that an increase in porosity or permeability leads to better humidification. Moreover, increase in inlet temperature of dry and wet channels as well as inlet mass flowrate of water vapor would enhance humidifying process. On the other hand, by reduction in inlet mass flowrate of gas channel and thickness of the porous medium in membrane, better humidifier performance would be achieved. To investigate the geometric parameters, three different channel types including stepped, sinusoidal and zigzag are considered. It is found that stepped geometry has the best performance in humidifying.

     

Dust acoustic solitary and shock waves in strongly coupled dusty plasmas with nonthermal ions

The Korteweg-de Vries-Burgers (KdV-Burgers) equation and modified Korteweg-de Vries-Burgers equation are derived in strongly coupled dusty plasmas containing nonthermal ions and Boltzmann distributed electrons. It is found that solitary waves and shock waves can be produced in this medium. The effects of important parameters such as ion nonthermal parameter, temperature, density and velocity on the properties of shock waves and solitary waves are discussed.     

Solitons of the KP equation in dusty plasma with variable dust charge and two temperature ions: energy and stability

The propagation of nonlinear waves in dusty plasmas with variable dust charge and two temperature ions is analyzed. By using the reductive perturbation theory, the Kadomtsev-Petviashivili (KP) equation is derived. A Sagdeev potential has been investigated. This potential is used to study the stability conditions for existence of solitonic solutions. Also, it is shown that a rarefactive soliton can exist in most of the cases. The energy of the soliton has been calculated and by using the standard normal-mode analysis a linear dispersion relation has been obtained. The effects of variable dust charge on the amplitude, width and energy of soliton and its effects on the angular frequency of linear wave are also discussed.     

Indole 3-alkylation/vinylation under catalysis of the guanidinium ionic liquids

Two ionic liquids, N,N,N,N-tetramethylguanidinium trifluoroacetate (TMGT) and the unprecedented N,N,N,N-tetramethylguanidinium triflate (TMGT_f), were used as catalyst solvents in condensations between indoles and arylaldehydes or 1,3-diketones providing a simple and efficient method for synthesis of bis(3-indolyl)methanes or casually 3-alkenylindoles due to stereoelectronic concerns of reactants. The ionic liquids are easily separated and reused for several times.