A novel method for the reduction of sulfoxides with the N,N,N’,N’-tetrabromobenzene-1,3-disulfonamide (TBBDA)/PPh3 system

A new method is described for the reduction of sulfoxides to sulfides using N,N,N’,N’-tetrabromobenzene-1,3-disulfonamide [TBBDA] in combination with triphenylphosphine. Good to excellent yields, short reaction times, high efficiency and facile isolation of the desired products are the advantages of this method.     

Synthese et Etude Conformationnelle Par RMN (1H, 13C, 31P) et DFT des Cycloalcoxyphosphinallenes et des Hydrazones β-Cycloalcoxyphosphonatees

Abstract

The addition of hydrazine and its derivatives to cycloalkoxyphosphinallenes leads to β-(5,5-dialkyl-2-oxo-1,3,2-dioxaphosphoranyl)-hydrazones in good yields. The structure of the obtained compounds were elucidated by the NMR (¹H, ¹³C, ³¹P) spectroscopy and density functional theory (DFT) calculations at B3LYP/6-311++G (2d, 2p) level of theory.     

Two new Weyl-type bounds for the Dirichlet Laplacian

In this paper, we prove two new Weyl-type upper estimates for the eigenvalues of the Dirichlet Laplacian. As a consequence, we obtain the following lower bounds for its counting function. For , one has

and

where

is a constant which depends on , the dimension of the underlying space, and Bessel functions and their zeros.

     

Biological Activities Evaluation of Enantiopure Isoxazolidine Derivatives: In Vitro,In Vivo and In Silico Studies

Applied Biochemistry and Biotechnology - A series of enantiopure isoxazolidines (3a–c) were synthesized by 1,3-dipolar cycloaddition between a (−)-menthone-derived nitrone and various...     

Synthesis and characterization of sulfamic acid supported on Fe3O4 nanoparticles: A green,versatile and magnetically separable acidic catalyst for oxidation reactions and Knoevenagel condensation

Sulfamic acid immobilized on diethylenetriamine functionalized Fe₃O₄ nanoparticles (SA‐DETA‐Fe₃O₄) was successfully prepared and characterized by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), vibrating sample magnetometer (VSM), thermo gravimetric analysis (TGA), X‐Ray diffraction (XRD) and scanning electron microscopy (SEM). The sulfamic acid was found as a magnetically separable and highly active catalyst for the oxidative coupling thiols, oxidation of sulfides. Furthermore, the SA‐DETA‐Fe₃O₄ showed the high catalytic activity in Knoevenagel condensation of aromatic aldehydes with active methylene compounds (malononitrile and ethyl cynoacetate). The nanosolid catalyst could be easily recovered by a simple magnetic separation and reused for many cycles without deterioration in catalytic activity.     

An Algorithm for the Single-item Capacitated Lot-Sizing Problem with Concave Production and Holding Costs

We consider a multi-period single-item production scheduling problem with a deterministic, time-varying demand pattern and concave cost functions. Optimal production lot sizes, so as to minimize the total costs of production, set-up, and inventory, are determined subject to dynamic production capacity and no backlogs. The proposed algorithm was tested extensively by solving several randomly generated problems with varying degrees of complexity. The proposed algorithm appears to perform quite reasonably for practical applications.     

A posteriori analysis: error estimation for the eighth order boundary value problems in reproducing Kernel space

In the previous work (Akram and Rehman Numer. Algor. 62 527–540 2013), Akram and Rehman presented the reproducing kernel method (RKM) for solving various eighth order boundary value problems. However, an effective error estimation for this method has not yet been discussed. This work is devoted to deal with this problem. Some other aspects of the RKM will be considered such as convergence analysis and numerical implementations.     

A note on regularity and positive definiteness of interval matrices

We present a sufficient regularity condition for interval matrices which generalizes two previously known ones. It is formulated in terms of positive definiteness of a certain point matrix, and can also be used for checking positive definiteness of interval matrices. Comparing it with Beeck’s strong regularity condition, we show by counterexamples that none of the two conditions is more general than the other one.