Treatment of synthetic catechol solution by electrocoagulation-magnetic granular activated pomegranate peel carbon: A cost-effective approach

The studies on purifying water and wastewaters contaminated with phenolic compounds have always been set up within recent years either full-scale or lab-scale experiments. In this research, treatment of the synthesized catechol (CC) solution was done by using magnetized granular activated pomegranate peel carbon (GAPPC) simultaneously with an electrocoagulation (EC) system for the first time. The experiments on both the EC-magnetic GAPPC and the magnetic GAPPC to find the optimum operating parameters like pH, contact time (CT), supportive electrolyte concentration, current densities (DC), adsorbent dosage, temperature to remove CC were conducted in batch-mode. The highest removal rate (88%) was achieved at pH = 6-8, CT = 30, supportive electrolyte = 0.25 g/L, DC = 0.5 A/m2, magnetic GAPPC dosage = 0.25 g/L. Under this condition, the rate of anode dissociation was 2.9 mg/L as the produced coagulant, the used electrical energy was 3.5 kW h, and the produced sludge rate was not more than 220 mg/L. However, synergistic order to remove CC could be as EC-magnetic GAPPC > EC > > magnetic GAPPC. Chromatographic analysis suggested that benzoquinone could be regarded as EC degradation intermediate of CC and simple aliphatic acids as its semifinal oxidation products along with Fe-bonded complexes. Adsorption isotherm followed Freundlich model having higher R2 representing multilayer adsorption. The adsorption kinetics investigation demonstrated that the pseudo-second-order model better fits the experimental data rather with higher R2. The cost analysis revealed that treating aqueous CC solutions using EC-magnetic GAPPC does not cost more than $0.8. PRACTITIONER POINTS: Using simultaneously electrocoagulation and magnetic AC made by pomegranate peel is extremely cost-effective having high efficiency (88%) for removing CC. Benzoquinone is the intermediate of CC electrochemical degradation through EC-magnetic GAPPC treatment process, and formic and acetic acids, and Fe-bonded complexes as its semifinal and final products. Adsorption mechanism was multilayer following Freundlich isotherm model and kinetics adsorption was well-fitted with pseudo-second-order model. CC adsorption by magnetic GAPPC was a spontaneous and exothermal mechanism. The synergic order of EC-magnetite GAPPC was EC-magnetic GAPPC > EC > > magnetic GAPPC.

Electrochemical Arylation of Electron-Deficient Arenes through Reductive Activation

An electrochemical method has been developed to achieve arylation of electron-deficient arenes through reductive activation. Various electron-deficient arenes and aryldiazonium tetrafluoroborates are amenable to this transformation within the conditions of an undivided cell, providing the desired products in up to 92 % yield. Instead of preparing diazonium reagents, these reactions can begin from anilines, and they can be carried out in one pot. Electron paramagnetic resonance studies indicate that cathodic reduction of quinoxaline occurs using the transformation. Moreover, cyclic voltammetry indicates that both quinoxaline and aryl diazonium salt have relatively low reduction potentials, which suggests they can be activated through reduction during the reaction.

Electrochemical strategies for C-H functionalization and C-N bond formation

Conventional methods for carrying out carbon-hydrogen functionalization and carbon-nitrogen bond formation are typically conducted at elevated temperatures, and rely on expensive catalysts as well as the use of stoichiometric, and perhaps toxic, oxidants. In this regard, electrochemical synthesis has recently been recognized as a sustainable and scalable strategy for the construction of challenging carbon-carbon and carbon-heteroatom bonds. Here, electrosynthesis has proven to be an environmentally benign, highly effective and versatile platform for achieving a wide range of nonclassical bond disconnections via generation of radical intermediates under mild reaction conditions. This review provides an overview on the use of anodic electrochemical methods for expediting the development of carbon-hydrogen functionalization and carbon-nitrogen bond formation strategies. Emphasis is placed on methodology development and mechanistic insight and aims to provide inspiration for future synthetic applications in the field of electrosynthesis.

Synthetic Organic Electrochemical Methods Since 2000: On the Verge of a Renaissance

Electrochemistry represents one of the most intimate ways of interacting with molecules. This review discusses advances in synthetic organic electrochemistry since 2000. Enabling methods and synthetic applications are analyzed alongside innate advantages as well as future challenges of electroorganic chemistry.

Use of Electrochemistry in the Synthesis of Heterocyclic Structures

The preparation and transformation of heterocyclic structures have always been of great interest in organic chemistry. Electrochemical technique provides a versatile and powerful approach to the assembly of various heterocyclic structures. In this review, we examine the advance in relation to the electrochemical construction of heterocyclic compounds published since 2000 via intra- and intermolecular cyclization reactions.

Regioselective synthesis of pyrrolo[1,2-a]imidazoles and imidazo[1,2-a]-pyridines

A concise synthesis of pyrrolo[1,2-a]imidazoles and imidazo[1,2-a]-pyridines by regioselective aza-ene additions and regioselective cyclic–condensation reactions of HKAs with ethyl 3-benzoylacrylate derivatives under catalyst-free conditions.

Recent developments of ketene dithioacetal chemistry

Ketene dithioacetals are versatile intermediates in organic synthesis. Extensive research, since the last decade, has given rise to new prospects in their chemistry. The objective of this review is twofold: first, to highlight the new prospects in the chemistry of functionalized ketene dithioacetals, and second, to provide an intrinsic link between ketene dithioacetal groups and a variety of other functional groups, which has brought out many new facts that will assist in future designs.