Highly selective catalytic Friedel–Crafts sulfonylation of aromatic compounds using a FeCl3-based ionic liquid

Friedel–Crafts sulfonylation of aromatic compounds was carried out using FeCl₃-based ionic liquid. These liquids serve as efficient media as well as Lewis acid catalyst.     

An experimental study on particle formation in emulsifier-free emulsion polymerization of styrene

Particle formation in polymerization of styrene induced within two stratified layers of a monomer and water containing an initiator was studied in the absence of emulsifiers and stirring. A polymerization-induced decrease of interfacial surface tension was observed. The particle size distribution was characterized by dynamic light scattering during polymerization. The results confirm particle nucleation through spontaneous emulsification process.     

The $$\varvec{N}$$ N -soliton,fusion, rational and breather solutions of two extensions of the (2+1)-dimensional Bogoyavlenskii–Schieff equation

Nonlinear Dynamics - The aim of this work is to analyze and explore the dynamics of two extensions of the Bogoyavlenskii–Schieff equation. The Hirota bilinear method is applied to the...     

Singularity Time Scale of the Kardar–Parisi–Zhang Equation in 2+1 Dimensions

A master equation for the Kardar–Parisi–Zhang (KPZ) equation in 2+1 dimensions is developed. In the fully nonlinear regime we determine the finite time scale of the singularity formation in terms of the characteristics of forcing. The exact probability density function of the one point height field is obtained correspondingly.     

Multi-domain Fourier-continuation/WENO hybrid solver for conservation laws

We introduce a multi-domain Fourier-continuation/WENO hybrid method (FC–WENO) that enables high-order and non-oscillatory solution of systems of nonlinear conservation laws, and which enjoys essentially dispersionless, spectral character away from discontinuities, as well as mild CFL constraints (comparable to those of finite difference methods). The hybrid scheme employs the expensive, shock-capturing WENO method in small regions containing discontinuities and the efficient FC method in the rest of the computational domain, yielding a highly effective overall scheme for applications with a mix of discontinuities and complex smooth structures. The smooth and discontinuous solution regions are distinguished using the multi-resolution procedure of Harten [J. Comput. Phys. 115 (1994) 319–338]. We consider WENO schemes of formal orders five and nine and a FC method of order five. The accuracy, stability and efficiency of the new hybrid method for conservation laws is investigated for problems with both smooth and non-smooth solutions. In the latter case, we solve the Euler equations for gas dynamics for the standard test case of a Mach three shock wave interacting with an entropy wave, as well as a shock wave (with Mach 1.25, three or six) interacting with a very small entropy wave and evaluate the efficiency of the hybrid FC–WENO method as compared to a purely WENO-based approach as well as alternative hybrid based techniques. We demonstrate considerable computational advantages of the new FC-based method, suggesting a potential of an order of magnitude acceleration over alternatives when extended to fully three-dimensional problems.     

On coLaskerian module and local cohomology

The notion of generalized Laskerian modules was introduced recently by the authors. In this paper, we continue our investigation of such modules. Moreover, we are going to generalize some results on finiteness of associated primes of local cohomology modules to the category of generalized Laskerian modules.     

Mild bromination of unreactive aromatic compounds

N,N,N′,N′-Tetrabromobenzene-1,3-disulfonamide and poly(N,N′-dibromo-N-ethylene-benzene-1,3-disulfonamide) in concentrated H₂SO₄ can be used as efficient reagents for the mild bromination of unreactive arenes at room temperature, under solvent-free conditions, in good yields.     

An Efficient Solvent Free Synthesis of 1,8-Dioxo-octahydroxanthene Using p-Toluene Sulfonic Acid

A simple and efficient method for the synthesis of 1,8‐dioxo‐octahydroxanthene by using p‐toluenesulfonic acid as a catalyst under solvent free conditions is described, which involves cyclization of 2,2‐arylmethylenebis(3‐hydroxy‐5,5‐dimethyl‐2‐cyclohexene‐1‐one) that was obtained firstly by the reaction of dimedone with aromatic aldehydes in water as solvent and catalyst at room temperature. The experimental procedures in the two steps are very simple and the products are formed in excellent yields.