Fe nano particles mediated C-N bond-forming reaction: Regioselective synthesis of 3-[(2-chloroquinolin-3-yl)methyl]pyrimidin-4(3H)ones

An efficient and regioselective N-alkylation of 4(3H)-pyrimidone with various electrophiles in the presence of Fe nano particle is reported. The catalyst initiates N-alkylation of amides by alkyl chlorides. The reaction of equimolar 4(3H)-pyrimidone and 2-chloro-3-(chloromethyl)quinolines in the presence of KOH and Fe nano particle (5 mol %) in DMSO solution under reflux condition formed 3-[(2-chloroquinolin-3-yl]methyl)pyrimidin-4(3H)ones.     

Stability of Volterra diffusion equations with time delays

This paper is concerned with asymptotic stability of a system of reaction-diffusion equations which is expressed in terms of Volterra integrals, under homogeneous Dirichlet boundary conditions. The effect of diffusion and delays on the stability of the system are analyzed, and sufficient conditions are given for the existence of positive solutions of the corresponding steady-state problem. Their global attraction with respect to nonnegative solutions of the time-dependent system is discussed. The main tools are Lyapunov functionals, positive definite kernels, and Laplace transforms.     

Piezoelectricity in quasicrystals: A group-theoretical study

Group-theoretical methods have been accepted as exact and reliable tools in studying the physical properties of crystals and quasicrystalline materials. By group representation theory, the maximum number of non-vanishing and independent second-order piezoelectric coefficients required by the seven pentagonal and two icosahedral point groups — that describe the quasicrystal symmetry groups in two and three dimensions — is determined. The schemes of non-vanishing and independent second-order piezoelectric tensor components needed by the nine point groups with five-fold rotations are identified and tabulated employing a compact notation. The results of this group-theoretical study are briefly discussed.      

Detection of binary images in noise

Detection of binary images in noise is considered in the light of statistical detection theory, with particular reference to information storage systems. The different disturbances are classified into system noise and transparency noise. The receiver operating characteristics (ROC) have been obtained when the scanned binary image is corrupted by additive white Gaussian noise and multiplicative speckle. It is shown that improvement in ROC with signal-to-noise ratio (SNR) is less pronounced in the presence of speckle.     

Determination of t,t-muconic acid in urine samples using a molecular imprinted polymer combined with simultaneous ethyl chloroformate derivatization and pre-concentration by dispersive liquid–liquid microextraction

The present communication describes the preparation and evaluation of a molecularly imprinted polymer (MIP) as a solid-phase extraction (SPE) sorbent and simultaneous ethyl chloroformate (ECF) derivatization and pre-concentration by dispersive liquid–liquid microextraction (DLLME) for the analysis of t,t-muconic acid (t,t-MA) in urine samples using gas chromatography–mass spectrometry. The imprinting polymer was prepared using methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, 2,2-azobisisobutyronitrile as the initiator and t,t-MA as a template molecule. The imprinted polymer was evaluated for its use as a SPE sorbent by comparing both imprinted and non-imprinted polymers in terms of the recovery of t,t-MA from urine samples. Molecular modelling studies were performed in order to estimate the binding energy and efficiency of the MIP complex formed between the monomer and the t,t-MA. Various factors that can affect the extraction efficiency of MIP, such as the loading, washing and eluting conditions, were optimized; other factors that can affect the derivatization and DLLME pre-concentration were also optimized. MIP in combination with ECF derivatization and DLLME pre-concentration for t,t-MA exhibits good linearity, ranging from 0.125 to 2 μg?mL^?1 (R ²?=?0.9971), with limit of detection of 0.037 μg?mL^?1 and limit of quantification of 0.109 μg?mL^?1. Intra- and inter-day precision was found to be <6 %. The proposed method has been proven to be effective and sensitive for the selective pre-concentration and determination of t,t-MA in urine samples of cigarette smokers.

Improved Erlenmeyer Synthesis with 5‐Thiazolone and Catalytic Mn(II) Acetate. Crystal Structure Confirmation of the Reaction Stereochemistry

2‐Phenylthiazolin‐5‐one ( 5 , a thioazlactone) condenses with various aldehydes in the presence of the mild base Mn(II) acetate as catalyst in CH₂Cl₂ solution. This leads to the corresponding Erlenmeyer reaction products ( 6 ) in excellent yields in the case of aromatic aldehydes and moderate yields in others. The mildness of the reaction conditions is apparently enabled by the aromaticity of the (putative) intermediate thiazolone anion. The structure and stereochemistry (Z) of the product derived from i‐BuCHO was confirmed by single crystal X‐ray diffraction. This study overcomes key limitations of the classical Erlenmeyer synthesis and also introduces the relatively nontoxic Mn(II) acetate as a reagent in heterocyclic chemistry.