CONVERSION OF EPOXIDES INTO 2-HYDROXYETHYL THIOCYANATES WITH NH4SCN IN THE PRESENSE OF 2,6-BIS[2-(O -AMINO PHENOXY)METHYL]-4-BROMO-1-METHOXYBENZENE (BABMB) AS CATALYST

A convenient and efficient procedure for the ring-opening of 1,2-epoxyethanes with ammonium thiocyanate in the presence of 2,6-bis[2-(o -aminophenoxy)methyl]-4-bromo-1-methoxybenzene (BABMB) is described. In this study, a reagent and conditions have been discovered with which the individual 2-hydroxyethyl thiocyanates can be synthesized in high yield and with more than 90% regioselectivity. Thus, several 2-hydroxyethyl thiocyanates, useful intermediates toward biological-active molecules, are easily obtained in very good yields.     

Ion‐flotation Separation of Cd(II), Co(II) and Pb(II) Traces Using a New Ligand before Their Flame Atomic Absorption Spectrometric Determinations in Colored Hair and Dryer Agents of Paint

A simple, rapid and inexpensive method for separation and preconcentration of some traces of hazardous elements is presented prior to their flame atomic absorption spectrometric determinations. At pH 6.5; cadmium(II), cobalt(II) and lead(II) were separated simultaneously with 1,2‐bis((1H‐benzo[d]imidazol2‐yl)methoxy)benzene (BBIMB) as a new complexing agent and floated after adding sodium dodecyl sulfate (SDS) as a foaming reagent. The floated layer was then eluted by concentrated nitric acid in methanol and introduced to the flame atomic absorption spectrometer (FAAS). The effects of pH, concentration of BBIMB, type and amount of surfactant as the floating agent, type and amount of eluting agent and influence of foreign ions on the recoveries of the analyte ions were investigated. Also, by using a non‐linear curve fitting method the formation constants of Cd(II), Co(II) and Pb(II) complexes were obtained 1.02 × 10⁶, 1.17 × 10⁶ and 1.46 × 10⁶, respectively. The detection limits of Cd(II), Co(II) and Pb(II) ions were 1.2, 0.7 and 0.5 μg/L, respectively. The enrichment factors were 45.0, 42.0 and 39.0 for Cd(II), Co(II) and Pb(II) ions, respectively. The proposed procedure was then successfully applied for determination of those heavy metals in colored human hair and dryer agents of paint samples.     

Effects of relativistic and ponderomotive nonlinearities on the interaction of high-power laser beam with an inhomogeneous warm plasma

The influence of relativistic-ponderomotive nonlinearities and the plasma inhomogeneity on the nonlinear interaction between a high-power laser beam and a warm underdense plasma are studied. It is clear that the relativistic ponderomotive force and the electron temperature modify the electron density distribution and consequently change the dielectric permittivity of the plasma. Therefore, by presenting the modified electron density and the nonlinear dielectric permittivity of the warm plasma, the electromagnetic wave equation for the propagation of intense laser beam through the plasma is derived. This nonlinear equation is numerically solved and the distributions of electromagnetic fields in the plasma, the variations of electron density, and plasma refractive index are investigated for two different background electron density profiles. The results show that the amplitude of the electric field and electron density oscillations gradually increase and decrease, during propagation in the inhomogeneous warm plasma with linear and exponential density profiles, respectively, and the distribution of electron density becomes extremely sharp in the presence of intense laser beam. It is also indicated that the electron temperature and initial electron density have an impact on the propagation of the laser beam in the plasma and change the plasma refractive index and the oscillations' amplitude and frequency. The obtained results indicate the importance of a proper choice of laser and plasma parameters on the electromagnetic field distributions, density steepening, and plasma refractive index variations in the interaction of an intense laser beam with an inhomogeneous warm plasma.     

Molybdatophosphoric Acid/NaNO2 as an Efficient Procedure for the Chemoselective N‐Nitrosation of Secondary Amines

A combination of molybdatophosphoric acid and sodium nitrite in the presence of wet SiO₂ was used as an effective nitrosating agent for the nitrosation of secondary amines under mild and heterogeneous conditions in good to excellent yields. Also, the results of a computational study are investigated in the gas phase for geometry and properties of proposed structures.     

Synthesis of new 1,5-diaryl-3-(arylamino)-1H-pyrrol-2(5H)-ones under catalyst-free and solvent-free conditions

Several new 1,5-diaryl-3-(arylamino)-1H-pyrrol-2(5H)-ones were synthesized via the three-component condensation reaction of aldehydes, aromatic amines, and ethyl pyruvate under catalyst-free and solvent-free conditions. Also, 5-(4-hydroxyl-3-nitrophenyl)-1-(4-methoxy-phenyl)-3-(4-methoxyphenylamino)-1,5-dihydro-pyrrol-2-one was synthesized using oxime instead of aldehyde. The eco-friendly, simple procedure, green procedure, catalyst-free and solvent-free conditions, short reaction times, and high yields of the products are the advantages of this method.     

Analytical Study on the Rate of Sound Transmission Loss in Single Row Honeycomb Sandwich Panel Using a Numerical Method

Honeycomb structures have recently, replaced with conventional homogeneous materials. Given the fact that sandwich panels containing a honeycomb core are able to adjust geometric parameters, including internal angles, they are suitable for acoustic control applications. The main objective of this study was to obtain a transmission loss curve in a specific honeycomb frequency range along with same overall dimensions and weight. In this study, a finite element model (FEM) in ABAQUS software was used to simulate honeycomb panels, evaluate resonant frequencies, and for acoustic analysis. This model was used to obtain acoustic pressure and then to calculate the sound transmission loss (STL) in MATLAB software. Vibration and acoustic analysis of panels were performed in the frequency range of 1 to 1000 Hz. The models analyzed in this design includes 14-single row-honeycomb designs with angles of −45°, −30°, −15°, 0°, +15°, +30°, +45°. The results showed that a-single row and −45°cell angle honeycomb panel in the frequency range of 1 to 1000 Hz had the highest STL as well as the highest number of frequency modes (90 mods). Furthermore, the panel had the highest STL regarding the area under the STL curve (dB∙Hz). The panels containing more frequency mods, have a higher transmission loss. Moreover, the sound transmission loss is more sensitive to the cell angle variable (θ). In other studies, the STL was more sensitive to the number of honeycomb cells in the horizontal and vertical directions, as well as the angle of cells.     

A simple and efficient route for the synthesis of di and tri(bis(indolyl) methanes) as new triarylmethanes

Preparation of di and tri(bis(indolyl) methanes) from di and trialdehydes and indoles in the presence of silica sulfuric acid was described. Reactions proceeded in good to excellent yields in acetonitrile as solvent at room temperature.     

Using acidic ionic liquid 1-butyl-3-methylimidazolium hydrogen sulfate in selective nitration of phenols under mild conditions

Selective nitration of phenols with sodium nitrate was carried out in the presence of acidic ionic liquid 1-butyl-3-methylimidazolium hydrogen sulfate at room temperature in good to high yields and short reaction times. The use of inexpensive and relatively non toxic acidic reagent is an advantage of this method.