Sharif Digital Repository

An ecofriendly one-pot multicomponent reaction of 1,3-dicarbonyl compounds, aldehydes, and malononitrile was carried out in a different deep eutectic solvent (DES) based on choline chloride, to synthesize highly functionalized benzopyran and pyran derivatives under catalyst-free conditions. The results showed that urea:choline chloride based DES is the best solvent and is successfully applicable to a wide range of aldehydes, active methylene compounds with high yields (75-95%) and short reaction times (1-4 h)  

An oxide gold ore was subjected to chloride/hypochlorite leaching at room temperature. The effects of three factors, including Ca(OCl)2 vs. NaOCl, OCl- concentration, and HCl concentration on gold leaching performance were investigated. Due to formation of CaOCl+ complex in solution and hence less reactivity, calcium hypochlorite produces a sluggish gold leaching kinetics, taking twice the time (46 h) to achieve maximum gold recovery of 58% compared to sodium hypochlorite. 10 g/L of total initial hypochlorite species in solution produces reasonable gold recoveries. The amount of added HCl and hence the initial pH was found to have a major effect on gold leaching kinetics and maximum gold... 

The present work describes the application of nano CoCuFe2O4 toward the coupling reaction of acyl chlorides with terminal alkynes. By this catalytic system, ynone derivatives were formed in high yields via a palladium-free strategy. This protocol avoids the use of phosphine ligands as well as toxic CO sources. Recovery of catalyst by employing an external magnetic field and its reuse up to 9 consecutive trials confirm the robustness of this catalytic system. © 2017 Elsevier B.V  

Palladium nanoparticles immobilized on the magnetic nanoparticles@2-amino-N-(2-aminoethyl) benzamide (MNPs@A-N-AEB.Pd0) have been presented as an efficient, and reusable magnetically heterogeneous catalyst for the C-O coupling reaction, namely Ullmann condensation reactions in an aqueous medium. This heterogeneous catalyst shows superior reactivity for the C-O arylation of different aryl halide (chloride, bromide, and iodide) with phenol derivatives to afford the desired products in good to excellent yields within short reaction time. Moreover, the catalyst can be easily recovered and reused for seven runs without loss of catalytic activity. The catalyst was characterized by several... 

Buoyancy-induced fluid flow, which is responsible for most forms of macro-segregation and channel-type segregates in castings, is not directly controllable. If left uncontrolled, natural convection will contribute to non-uniform distribution of alloy constituents and grain structure during solidification of a casting. Non-uniform distribution of chemical composition and physical structure in an alloy casting can significantly affect the reliability of mechanical components. Therefore, materials with acceptable defects can be produced only by trial-and-error and their acceptability is determined by costly inspections. We present a novel technique to control the formation of chimneys and... 

Efficient synthesis of protected and unprotected chlorohydrins has been achieved by ring opening of epoxides with acetyl/benzoyl chloride and TMSCl using a catalytic amount of ZnO as a reusable catalyst. The applicability of ZnO is further extended by performing the cleavage of the natural product 5,6-epoxysitosterol with acetyl chloride. © 2009 Wiley Periodicals, Inc  

In this research, the separation of tellurium from selenium was studied from chloride solution by TBP extractant. In the batch experiments, the experimental findings indicated that the feed acidity, TBP concentration, and contact time were optimized to achieve the high separation factor. In continuous mode of pulsed disc and doughnut column, the impacts of operating parameters have been discussed on the distribution coefficients of selenium and tellurium, and mass transfer enhancement. A new model for predicting Koca was proposed in terms of holdup values, Sherwood, Reynolds, and Schmidt numbers, which has an acceptable agreement with the mass transfer data. © 2020 Taylor & Francis Group,... 

A simple, efficient, and general method has been developed for the conversion of aldehydes to 1,1-diacetates with the use of acetic anhydride and solid LiClO4 under first solvent-free and mild conditions in good yields. This method applies to not only simple but also to conjugated aldehydes. © 2005 Elsevier B.V. All rights reserved  

In this study, the corrosion behaviour of Ni-Co alloys with low Co content, electroplated on steel substrate in sulphate bath, was investigated. The morphology of coatings was studied by optical and SEM microscopy. The corrosion products were analyzed using EDX. The results showed that Ni-1%Co coatings had a better corrosion resistance 0.30, 0.92 and 3.75 mpy for atmospheric, salt spray and polarization tests, respectively. These are 0.41, 1.20 and 5.40 mpy for pure nickel coatings that indicate the least corrosion resistance. Surface analysis revealed the presence of oxides, sulphides and chlorides in corrosion products  

Anatase nanostructured coating has been prepared on 316 L stainless steel by sol-gel dip coating. The topography of the coatings surface has been analyzed using atomic force microscopy. The anticorrosion performance of the coatings has been evaluated using polarization curves. Effects of calcination temperature, withdrawal speed and times of coating on corrosion protection have been studied. The results showed calcination temperature of 400°C and withdrawal speed of 10 cm/min are desirable conditions to achieve high corrosion protection of 316 L stainless steel in chloride containing environments. Coatings with 3 times exhibit better resistance against corrosion in 0.5 molar NaCl solutions.... 

The hardness of the Ni-Cr alloy which is electrodeposited in chloride solution, is optimized by design of experiment method (central composite design). Various parameters were evaluated in order to find significant factors in this process. Frequency, duty cycle, current density and temperature were selected as effective factors. Analyses of variance (ANOVA) were performed on the results of the designed experiments. The best model which can predict the hardness of the Ni-Cr alloy electrodeposits was found whereas the frequency and quadratic behaviour of the current density were the most significant model terms. Serious interaction of the current density with frequency and duty cycle also were... 

The geometry structures of hexa-coordinated [NiLX]X complexes (X = Cl -, Br-, I-) {L = 8,9,18,19-tetrahydro-7H,17H- dibenzo[f,o] [1,5,9,13]dioxadiaza cyclohexadecine-8,18-diol} are optimized by density functional theory (DFT) using B3LYP/LANL2DZ. The calculated geometric parameters are in good agreement with the corresponding experimental values. Calculation results about these complexes show that dipole moment decreases, and the energy levels of HOMOs descend from iodo-complex to chloro-complex. The energy levels of HOMOs descend gently from iodo-complex to chloro-complex, while the energy levels of LUMOs in the present complexes are almost similar; therefore the energy gapes between HOMOs... 

A new cationic flocculant was synthesized by graft copolymerization of acrylamide (AM) and 3-(methacryloylamino)propyl]trimethylammonium chloride (MAPTAC) onto salep using free radical polymerization initiated by ammonium persulfate (APS) to produce cationic salep [S-g-P(AM-co-MAPTAC)]. Reaction parameters (monomers/salep ratio, concentration of reactants, MAPTAC/AM ratio, and APS) were optimized using a full factorial experimental design to obtain the highest settling rate for cement suspensions. The best performing product was characterized by gel permeation chromatography (GPC), FTIR, 1H NMR spectroscopy, and thermogravimetric analysis (TGA). The resulted cationic flocculant may be... 

The 2,6-bis(diphenylphosphino)pyridine/palladium catalytic system successfully catalyzes the Heck coupling reaction of less reactive aryl chlorides as well as aryl bromides with styrene to give the corresponding olefins in reasonable yields. TBAB (tetrabutylammoniumbromide) as an additive was found to be essential for these reactions. The results of Heck reaction exhibited a high selectivity (>99/1) favoring the trans product  

High molecular weight homopolymers of acrylamide (PAM) and (2-methacryloyloxyethyl) trimethyl ammonium chloride (PDMC) and copolymer of DMC with acrylamide (P(AM-co-DMC)) were synthesized using solution polymerization technique. The synthesized polymers were characterized by Fourier transform infrared (FTIR), 1HNMR, 13CNMR spectroscopy and differential scanning calorimetry (DSC) and viscometery. 1HNMR and 13CNMR studies confirmed the structure of the synthesized polymers. The behavior of the synthesized polymers was investigated in water-acetone and water-methanol mixtures. The plot of intrinsic viscosity of either PAM or P(AM-co-DMC) with respect to acetone (methanol)/water ratio in... 

Planar superstrate CuInS2 (CIS) solar cell devices are fabricated using totally solution-processed deposition methods. These Cd-free devices are structured by FTO/TiO2/In2S3/CIS/carbon, where TiO2 and In2S3 are deposited by spray pyrolysis, and a CIS film is deposited using spin-coating followed by annealing at 250 °C. The pasted carbon layer is utilized as the anode. No further sulfurization or selenization is employed. The Cu/In ratio in the ink is found as a critical factor affecting the morphology and crystallinity of the film as well as the photovoltaic performance of the device. An optimum Cu/In = 1.05 results in large-grain films with sharp diffraction peaks and, subsequently, optimal... 

Different strategies are employed in designing strong and selective anion receptors but stereoelectronic effects have been largely ignored. In this work, the stereo configuration of a non-interacting ether is found to have a large impact of more than two orders of magnitude on the binding of a rigid diol with tetrabutylammonium chloride in acetonitrile-d3. A favorable carbon-oxygen dipole and an intramolecular C-H⋯OH hydrogen bond in an equatorially substituted ether is found to be energetically more important than a stabilizing hydrogen bond in the corresponding axially oriented alcohol. IR spectroscopy is also used to probe the structures of the bound complexes and several binding motifs... 

Two non-ionic and hydrophilic surfactant additives, Tetronic-1107 and Triton X-100, were added to poly(vinyl chloride)/NMP polymeric solution to prepare ultrafiltration membranes via immersion precipitation. Surfactants at three different weight percentages up to 6 wt% were added, and the fabricated membranes were characterized and their performance for water treatment in the presence of bovine serum albumin (BSA) as a foulant was assessed. The scanning electron microscopy images indicated remarkable changes in morphology due to higher thermodynamic instability after surfactant addition. The membranes are more porous with more macro-voids in the sub-layer. Plus, the membranes become more... 

The interfacial properties of crude oil are highly complex and are not yet well understood. This study aimed to evaluate the effect of temperature (30-80°C) and pressure (3.44-27.58MPa) on the dynamic interfacial tension (IFT) of crude oil/aqueous solutions consisting of 15000ppm of salt containing different chloride anions, e.g. NaCl, KCl, MgCl2, and CaCl2. To reach this goal, several parameters, such as dynamic and equilibrium IFT, adsorption time, diffusivity of resin, and asphaltene as surface-active agents from bulk of crude oil towards fluid/fluid interface and surface excess concentration of them at the interface, were compared as a function of temperature, pressure, and ion type. The... 

The interfacial properties of crude oil are highly complex and are not yet well understood. This study aimed to evaluate the effect of temperature (30–80 °C) and pressure (3.44–27.58 MPa) on the dynamic interfacial tension (IFT) of crude oil/aqueous solutions consisting of 15 000 ppm of salt containing different chloride anions, e.g. NaCl, KCl, MgCl2, and CaCl2. To reach this goal, several parameters, such as dynamic and equilibrium IFT, adsorption time, diffusivity of resin, and asphaltene as surface-active agents from bulk of crude oil towards fluid/fluid interface and surface excess concentration of them at the interface, were compared as a function of temperature, pressure, and ion type....