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Sustainable electrosynthesis technologies are rapidly developing stimulated by the drive for sustainable chemical manufacturing and the increasingly accessible renewable electricity prices. The electrochemical utilization of easily available feedstock, such as carbon dioxide (CO2), has attracted significant attention as it can additionally help closing the disrupted carbon cycle. While direct CO2 reduction has benefited from recent advancements in the catalyst, electrolyte and system design, developments in electrochemical coupling of CO2 with organic precursors to yield value‐added chemicals have been lagging behind due to the apparent disconnect between the direct CO2 reduction and the organic electrosynthesis communities. Currently, electrocarboxylation reactions require high operating voltages, show low current densities, limited selectivity towards target products and are associated with low atom economy due to the reliance on sacrificial anode dissolution. Advancing this indirect electrochemical CO2 utilization strategy will enable sustainable synthesis of valuable chemicals including non‐steroidal anti‐inflammatory drugs and precursors for plasticizers and commercially‐relevant polymers—all of which are currently produced with high carbon footprint and low atom economy. This perspective discusses the current state‐of‐the‐art in electroorganic synthesis with CO2 as a one‐carbon synthon and suggests several transferrable strategies from direct CO2 reduction breakthroughs to advance electrocarboxylation and bring it closer to industrial implementation.

The sensitized photoexcitation of 2-diazocyclopentane-1,3-diones in the presence of THF leads to the insertion of the terminal N-atom of the diazo group into the α-С–Н bond of THF, producing the associated N-alkylhydrazones in yields of up to 63–71%. Further irradiation of hydrazones derived from furan-fused tricyclic diazocyclopentanediones culminates in the cycloelimination of furans to yield 2-N-(alkyl)hydrazone of cyclopentene-1,2,3-trione. By contrast, the direct photolysis of carbocyclic diazodiketones gives only Wolff rearrangement products with up to 90–97% yield.

A new approach towards the synthesis of multisubstituted thiophenes is elaborated based on Rh(II)-catalyzed domino reactions of acyclic diazoesters with α-cyanothioacetamides. It provides a way for the preparation of 5-amino-3-(alkoxycarbonylamino)thiophene-2-carboxylates, 2-(5-amino-2-methoxycarbonylthiophene-3-yl)aminomalonates and (2-cyano-5-aminothiophene-3-yl)carbamates with the preparative yields of up to 67%. It was also shown that α-cyanothioacetamides easily interact with dirhodium carboxylates to give rather stable 2:1 complexes, resulting in an evident decrease in the efficiency of the catalytic process at moderate temperatures (20–30 °C).

Rh(II)-сatalyzed reactions of aroyldiazomethanes, diazoketoesters and diazodiketones with α,β-unsaturated δ-aminoesters, in contrast to reactions of diazomalonates and other diazoesters, give rise to the Wolff rearrangement and/or oxidative cleavage of the initially formed N–H-insertion products. These oxidation processes are mediated by Rh(II) catalysts possessing perfluorinated ligands. The formation of pyrrolidine structures, characteristic for catalytic reactions of diazoesters, was not observed in these processes at all.

Electrochemistry represents a powerful sustainable method for chemical synthesis; however, its widespread application is limited due to the lack of exposure and appropriate basic training of synthetic chemists and engineers in electrochemistry and electrochemical engineering. The introduction of diverse laboratory practices to the current curricula will improve the understanding of electrochemistry and the theory behind its various applications. Here, we suggest an efficient laboratory experiment on the electrochemical reduction of CO[subscript 2] to CO using inexpensive and readily available materials, such as metal wires, plastic vessels, batteries, and a hand-held CO detector. Students learn to assemble a divided electrochemical cell and perform important electrochemical reactions, such as electrochemical CO[subscript 2] reduction and hydrogen evolution reaction. In this experiment, students analyze the rates of CO production under different electrolysis conditions and learn to understand the effects of operating parameters (applied potential, electrolyte concentration, and nature of the electrode) on the outcome of the reaction. This new comprehensive laboratory experiment is designed for students to better understand basic principles of electrochemistry and is suitable for undergraduate students.

Urea electrolysis is an emerging approach to treating urea‐enriched wastewater and an attractive alternative anodic process to the oxygen evolution reaction (OER) in electrochemical clean energy conversion and storage technologies (e. g. hydrogen production and CO2 electroreduction). While the thermodynamic potential for urea oxidation to dinitrogen is quite low compared to that of the OER, the catalysts reported to date require high overpotentials that far exceed those for the OER. Consequently, there is much room for improvement and rational catalyst design for the urea oxidation reaction (UOR). At the same time, due to the urea molecule having a more complex structure than water, UOR can lead to the formation of various products beyond the commonly assumed N2 and CO2. This concept article will critically assess recent efforts of the research community to decipher the formation mechanisms of UOR products focusing on the systematic analysis of the reaction selectivity. This work aims to analyze the current state of the art and identify existing gaps, providing an outlook for the future design of UOR catalysts with superior activity and selectivity by applying the knowledge of the molecular transformation mechanisms. [ABSTRACT FROM AUTHOR]

The electrochemical urea oxidation reaction (UOR) to N2 represents an efficient route to simultaneous nitrogen removal from N‐enriched waste and production of renewable fuels at the cathode. However, the overoxidation of urea to NOx− usually dominates over its oxidation to N2 at Ni(OH)2‐based anodes. Furthermore, detailed reaction mechanisms of UOR remain unclear, hindering the rational catalyst design. We found that UOR to NOx− on Ni(OH)2 is accompanied by the formation of near stoichiometric amount of cyanate (NCO−), which enabled the elucidation of UOR mechanisms. Based on our experimental and computational findings, we show that the formation of NOx− and N2 follows two distinct vacancy‐dependent pathways. We also demonstrate that the reaction selectivity can be steered towards N2 formation by altering the composition of the catalyst, e.g. doping the catalyst with copper (Ni0.8Cu0.2(OH)2) increases the faradaic efficiency of N2 from 30 % to 55 %. [ABSTRACT FROM AUTHOR]

The anaerobic digestion (AD) of N-enriched waste streams combined with nutrient recovery from AD effluents represents a cost-effective waste treatment technology for simultaneous production of biogas and recycled fertilizers. Herein, we demonstrate an efficient route towards S- or P-containing NH4NO3-based fertilizers via Ni(OH)2-catalyzed electrochemical oxidation of ammonia (AOR) to NH4NO3 in 0.1 M K2SO4 and 0.1 M K2HPO4 electrolytes. In this study, we examine how operating parameters, including the electrolyte, pH, applied potential, ammonia concentration, and temperature affect the AOR product distribution at Ni(OH)2 anodes. We show that under optimized conditions concentrated ammonia solutions can be efficiently converted into NH4NO3 with up to 72% faradaic efficiencies and up to 98% ammonia removal. Based on our extensive experimental data, we propose detailed mechanisms for the formation of major products (dinitrogen, nitrite, and nitrate) and for the first time experimentally demonstrate that ammonia-to-nitrite oxidation proceeds spontaneously on NiOOH, while the nitrite-to-nitrate step is purely electrochemical. The results of this work are expected to enable integration of AOR into AD of N-containing waste, thereby enabling a promising nutrient recovery strategy for building a circular economy. [ABSTRACT FROM AUTHOR]

We present a sacrificial anode-free approach to reductive homocoupling of organohalides that does not require a co-catalyst. In this approach, a divided electrochemical cell with aprotic and aqueous compartments separated by an anion exchange membrane enables coupling of the cathodic homocoupling reaction with anodic oxidation of urea. We show that, in contrast with traditional one-compartment cells relying on sacrificial anodes, the proposed cell configuration maintains stable cell voltage in the course of galvanostatic electrolysis. A synthetic potential of this method was assessed using a series of 13 organic bromides that demonstrated a strong dependence of the reaction outcome on the structure of the organic substrate, more specifically, the dissociation energy of the C–Br bond and the redox properties of formed radicals, which are discussed in detail. While not being suitable for the synthesis of byarylstructures, this method is excellent for C(sp³)-C(sp³) coupling to corresponding dimeric products with up to quantitative yields. Simultaneous electrochemical treatment of nitrogenous waste in the adjacent half-cell provides an additional incentive for wide adaptation of this sustainable synthetic approach. [ABSTRACT FROM AUTHOR]

We discuss the environmental and energetic benefits of coupling nitrogenous waste treatment with the electrochemical conversion of CO2 to value-added products via direct reduction or electrocarboxylation. In particular, we demonstrate that co-electrolysis of urea or ammonia with CO2 requires significantly lower cell voltages than CO2 electrolyzers relying on the oxygen evolution reaction as an anodic process. [ABSTRACT FROM AUTHOR]

The interaction of 5,5-dialkyl(diaryl)-substituted 4-diazo-3(2H)furanones with Brønsted acids (TFA, TsOH, etc.) causes elimination of nitrogen accompanied by 1,2-nucleophilic rearrangement, giving rise to exclusive formation of 4,5-dialkyl(diaryl)-substituted 3(2H)- furanones, ring-fused 3(2H)-furanones, and phenanthro[9,10-b]furan-3(2H)-ones in yields of up to 99%. The reaction is a new highly efficient way for the synthesis of multisubstituted 3(2H)furanones. [ABSTRACT FROM AUTHOR]

The occurrence of bifurcate H-bonds CAr-H···O=C in the structure of (diaryl)-tetrahydrofuranones was experimentally demonstrated using different methods and techniques. The consistent increasing spin-spin coupling constants 1 J(C,H) of the ortho-H-atoms and low-field shift of vC=O in IR spectra of 2,2-(diaryl)tetrahydrofuran-3(2 H)-ones relative to their 5,5-diaryl counterparts, as well as pronounced dependence of the ortho-C-H H-atoms chemical shifts on the temperature and solvent polarity along with X-ray diffraction analysis data unambiguously point to the existence of weak CAr-H···O=C H-bonds in these molecules. [ABSTRACT FROM AUTHOR]

Phosphazenes of vinyldiazocarbonyl compounds having cis stereochemistry of the functional groups on the vinyl bond readily produce pyridazines by a diaza-Wittig process, whereas their counterparts with trans configuration remain intact under similar reaction conditions. Upon UV irradiation trans-phosphazenes furnish pyridazines through a tandem trans-to-cis isomerization followed by intramolecular cyclization. At elevated temperatures trans-(triphenyl)- phosphazenes dissociate to give the initial vinyldiazo compounds, which produce pyrazoles in high yields. The first theoretical study on the mechanism of the diaza-Wittig process by DFT calculations at the M06-2X/6-31G(d) level of theory suggest that for the cis-phosphazenes a rapid tandem [2+2] cycloaddition/cycloelimination process with low energy barriers is preferred over trans isomers. [ABSTRACT FROM AUTHOR]

Thermolysis of 2,2,5,5-tetrasubstituted 4-diazodihydrofuran-3-ones in protic (BnOH) and aprotic (DMSO) media, in contrast to photolysis, gives rise to the formation of 2,2,4,5-substituted 3(2 H)-furanones as a result of 1,2-alkyl (aryl) shift. The thermal stability of diazodihydrofuranones in these processes is determined by the nature of the substituents at the C-5 atom of the heterocyclic structure: alkyl and electron-donating groups in the para-position of the aryl substituent notably reduce the persistence of diazodihydrofuranones, whereas aryl groups and electron-withdrawing substituents increase their stability considerably. Thermolysis of substituted 4-diazodihydrofuran-3-ones in DMSO solution is a first-order reaction that furnishes higher yields of furanones than thermolysis in BnOH. The reaction can serve as a preparative method for the synthesis of tetrasubstituted-3(2 H)-furanones. [ABSTRACT FROM AUTHOR]

Examines the proteins associated with caveolin (Cav) in canine lower esophageal sphincter (LES) using immunochemical studies with light microscopy, confocal microscopy and electron microscopy. Discussion of the nature and distribution of Cav in canine LES; Localization of neuronal nitric oxide synthase (nNOS) in canine LES; Colocalization of Cav-1 and nNOS with calcium-handling proteins.

Examines neuronal nitric oxide synthase in canine lower esophageal sphincter. Analysis of proteins associated with caveolin; Regulation of intracellular calcium concentration levels; Use of patch clamp studies to evaluate protein interactions.

Chemical equations for an article related to unusual reactions of diazocarbonyl compounds with α,β-unsaturated δ-amino esters by V. A. Nikolaev, appeared in the periodical "Beilstein Journal of Organic Chemistry" is presented.