Making electrochemistry easily accessible to the synthetic chemist

A significantly renewed interest in synthetic electrochemistry is apparent in the increasing number of publications over the last few years. Electrochemical synthesis offers a mild, green and atom efficient route to interesting and useful molecules, thus avoiding harsh chemical oxidising and reducing agents used in traditional synthetic methods. As such, encouraging broader application of electrochemistry by synthetic chemists should be a priority. Despite the renewed interest there remains a barrier to widespread adoption of this technology derived from the extra knowledge and specialised equipment required. This has led to a knowledge gap between experienced electrochemists and those new in the field. In this tutorial we will bridge the knowledge gap by providing an easily accessible introduction which will enable synthetic chemists new to the field to explore electrochemistry. We will discuss mechanistic considerations, the setup of an electrochemical reaction with all its components, trouble shooting and selected examples from the literature

Alternating polarity for enhanced electrochemical synthesis

Synthetic electrochemistry has recently become an exciting technology for chemical synthesis. The majority of reported syntheses use either constant current or constant potential, however a few use nonlinear profiles – mostly alternating polarity – to maintain efficiency throughout the process, such as controlling deposits on electrodes or ensuring even use of electrodes. However, even though parameters that are associated with such profiles, such as the frequency, can have a major impact on the reaction outcome, they are often not investigated. Herein, we report the crucial impact that the applied frequency of the alternating polarity has on the observed reaction rate of Cu(I)–NHC complex formation and demonstrate that this can be manipulated to give enhanced yield that is stable over extended reaction times

Development of a multistep, electrochemical flow platform for automated catalyst screening

The development of an integrated multistep flow platform that incorporates high-throughput electrochemical synthesis of metal catalysts and catalysis screening is described. Ligand libraries can be screened through the implementation of an autosampler, and online HPLC analysis facilitates continuous monitoring of the reaction. The equipment is controlled via a computer which enables the process to be automated, with the platform running ligand/catalysis screens autonomously. The platform has been validated using a ubiquitous Cu–NHC catalysed click reaction, with conditions chosen so that the reaction does not run at full conversion, which allows the effect of different ligand precursors to be observed. An efficient cleaning step is crucial to the reproducibility of reactions, and alternating polarity ensures the long-term stability of the electrochemical reactor. This technology will enable the profiling of catalysts in continuous systems and accelerate the process of developing more sustainable base-metal catalysts in manufacturing processes

A Versatile Electrochemical Batch Reactor for Synthetic Organic and Inorganic Transformations and Analytical Electrochemistry

A standardized and versatile electrochemical batch reactor that has wide applicability in both organic and inorganic synthesis and analytical electrochemistry has been developed. A variety of synthetic electrochemical transformations have been performed to showcase the versatility and demonstrate the reactor, including the synthesis of five Cu(I)–NHC complexes, two Au(I)–NHC complexes, and one Fe(II)–NHC complex as well as an Fe(III)–salen complex. The reactor is based on a commercially available vial with an adapted lid, making it inexpensive and highly flexible. It features a fixed interelectrode distance, which is crucial for reproducibility, along with the ability to accommodate a variety of interchangeable electrode materials. The reactor has also been used in conjunction with a parallel plate, allowing rapid screening and optimization of an organic electrochemical transformation. Cyclic voltammetry has been performed within the reactor on a range of imidazolium salt analytes with the use of an external potentiostat. The ability to use this reactor for both analytical and synthetic organic and inorganic chemistry is enabled by a flexible and characterizable design