Polystyrene-supported 1-methylimidazolium tetrachloro ferrate: Synthesis, characterization, and application as an efficient and reusable heterogeneous catalyst for one-pot synthesis of 4h-chromene derivatives in aqueous media

Polystyrene-supported 1-methylimidazolium tetrachloroferrate (PS[mim][FeCl4]) was prepared and characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The catalytic activity of the heterogeneous catalyst was evaluated through one-pot synthesis of 2-amino-4H-chromene-3-carbonitriles via the three-component condensation reaction of aromatic aldehydes, malononitrile and dimedone or 2-naphthol in water. The heterogeneous catalyst could be recovered easily and reused five times without significant loss of its catalytic activity.               KEY WORDS: Green chemistry, Heterogeneous catalyst, 4H-chromene derivatives, Multi-component reactions, One-pot synthesis Bull. Chem. Soc. Ethiop. 2018, 32(3), 531-540.DOI: https://dx.doi.org/10.4314/bcse.v32i3.1

Experimental Study on the Phase Equilibrium of Copper Matte and Silica-Saturated FeO x-SiO2-Based Slags in Pyrometallurgical WEEE Processing

The effects of the amphoteric and basic oxides alumina and lime on the phase equilibria of copper matte and silica-saturated slags were investigated at 1300 °C and PSO2 = 0.1 atm in a controlled CO-CO2-SO2-Ar gas atmosphere using a high-temperature isothermal equilibration technique followed by rapid quenching. The equilibrium phase compositions were obtained by Electron Probe X-ray Microanalysis. The relationship between the copper concentration in matte and the oxygen partial pressure, iron, and sulfur in matte was quantified. The pure iron-silicate slag exhibited the highest copper loss in slag, although the addition of alumina and lime decreased its value by approximately a quarter and a half, respectively, at a matte grade of 65 wt pct Cu. In contrast, copper and sulfur were highly distributed in the matte phase, and their deportment to the matte was favored by addition of alumina and lime.Peer reviewe

The effect of a temperature gradient on the phase formation inside a magnesia-chromite refractory in contact with a non-ferrous PbO-SiO2-MgO slag

Furnace relinings represent a major operating cost in pyrometallurgy. External cooling is, therefore, often used to reduce the chemical wear by limiting the slag infiltration depth, reducing the reaction kinetics and lowering the solubility of refractory components into the liquid slag. In this paper a new experimental setup is used to study the reaction between a synthetic PbO-SiO2 based slag and a magnesia-chromite refractory under a temperature gradient. Forsterite (Mg2SiO4) is formed throughout the sample, removing SiO2 from the infiltrated liquid slag. The resulting change in slag composition causes the liquidus temperature and the viscosity of the liquid to decrease partially countering the effect of the applied temperature gradient and resulting in the complete infiltration of the sample. The extent to which external cooling prolongs the lifetime of an industrial furnace thus depends on the slag properties and how they are modified after reaction with the refractory