Electro‐Synthesis of Organic Compounds with Heterogeneous Catalysis

Abstract

Electro-organic synthesis has attracted a lot of attention in pharmaceutical science, medicinal chemistry, and future industrial applications in energy storage and conversion. To date, there has not been a detailed review on electro-organic synthesis with the strategy of heterogeneous catalysis. In this review, the most recent advances in synthesizing value-added chemicals by heterogeneous catalysis are summarized. An overview of electrocatalytic oxidation and reduction processes as well as paired electrocatalysis is provided, and the anodic oxidation of alcohols (monohydric and polyhydric), aldehydes, and amines are discussed. This review also provides in-depth insight into the cathodic reduction of carboxylates, carbon dioxide, C=C, C≡C, and reductive coupling reactions. Moreover, the electrocatalytic paired electro-synthesis methods, including parallel paired, sequential divergent paired, and convergent paired electrolysis, are summarized. Additionally, the strategies developed to achieve high electrosynthesis efficiency and the associated challenges are also addressed. It is believed that electro-organic synthesis is a promising direction of organic electrochemistry, offering numerous opportunities to develop new organic reaction methods.

Recent Advances in Multicomponent Electro‐Organic (Electrochemical) Synthesis of Heterocycles

“…An electrochemical method was developed by Yang et al for the synthesis of substituted 1,2,4-triazole scaffolds (37) by combining aryl hydrazines (34), paraformaldehyde (35), NH 4 OAc (36), and alcohols (33) (Scheme 16). The t BuOK electrolysis was conducted with a constant current in an undivided cell equipped with a graphite rod anode and a Ni plate cathode.…”

“…The electrolysis was performed in an undivided cell equipped with a graphite felt (GF) anode and a platinum cathode with 20 mol% LiClO 4 catalyzed by n Bu 4 NI (TBAI) under constant current at a graphite carbon anode at 40 °C, acetonitrile, water-Et 4 with membraned as the solvent-electrolyte. To prepare substituted 1,2,4-triazoles (37), 1-benzylidene-2-phenylhydrazine (34), aldehyde (1'), and ammonium acetate (36) are assembled in an undivided cell through three-component reactions. Since raw materials are readily available, the yields are reasonable, scalability is feasible, and the catalytic process is experimentally convenient, the protocol presents a practical and appealing approach.…”

“…Moreover, they are valuable synthons in organic chemistry because they display significant biological activities and physicochemical properties. Weimin et al has reported a method for the synthesis of various 4-bromopyrazoles (46) using a threecomponent reaction of hydrazine (34), acetylacetone ( 9), and 2bromomalonate (45) which is environmentally friendly (Scheme 21). For 10 h in an undivided cell, n BuNBF 4 (20 mol%) was used as the electrolyte in MeCN at ambient temperature.…”

“…A variety of cyclic compounds can be synthesized with electrochemically induced cyclization reactions, and the specific type of cyclization reaction depends on the nature of substrate, desired product, and reaction conditions. [31][32][33][34]…”

Killing Two Birds with One Stone: Upgrading Organic Compounds via Electrooxidation in Electricity-Input Mode and Electricity-Output Mode

“…Therefore, it is imperative to develop clean and renewable alternatives for energy storage and chemical conversion. With the remarkable renaissance of electrochemical technology, and the constant inventions in the rapid development of renewable-based electricity technology, the technology of energy storage and conversion into chemicals is attracting great interest [ 1 , 2 , 3 , 4 , 5 , 6 ]. For example, hydrogen, a clean, flexible, cost-effective energy carrier for net-zero carbon (carbon-free) strategies, features a higher enthalpy of combustion (H 2 (g) + ½O 2 (g) → H 2 O(l) ΔH = −285.8 kJ/mol, high specific-energy-density) and enables the possibility of attaining secure and clean energy in the future.…”