The “Green” Electrochemical Synthesis of Periodate

Significance 

Periodate is an anion composed of iodine and oxygen. Technically, it is a monovalent inorganic anion obtained by deprotonation of periodic acid. Periodate has emerged as an important oxidizing agent in organic synthesis. In fact, a review of existing literature reveals that periodate enables a rich chemistry in the synthesis of active pharmaceutical ingredients. Unfortunately, its use in various technical applications is impeded by its scarcity coupled by its astronomical cost. This high cost is attributable to periodate’s purifications protocols. Electrochemistry is the most preferred method for periodate generation credit to its low environmental and financial costs. In this approach; however, lead dioxide (which is known to disintegrate slowly during electrolysis and cause contamination) is generally used as the anode. The toxicity of lead is inacceptable for regulated products, and its removal is cumbersome and economically prohibitive. To date, alternative anode materials have been investigated where most have yielded poorer results. Nonetheless, research for innovative electrode materials in the last decades has resulted in boron-doped diamond (BDD) anodes, which exhibit strongly improved properties.

Generally, BDD has been reported to be sustainable since it can be made from methane and possesses a similar overpotential for oxygen evolution at lead dioxide but a outstandingly superior durability. Previous experiments involving BDD revealed that salt used (mostly lithium iodate) and its pH have significant impact technically and cost-wise (the former refereeing to iodine precipitation and the latter; the exorbitant cost of the lithium salt). Therefore, to overcome these shortfalls, German researchers from the Department of Chemistry at Johannes Gutenberg University Mainz: Dr Sebastian Arndt, Dominik Weis and led by Professor Siegfried R. Waldvogel in collaboration with Dr. Kai Donsbach at the PharmaZell GmbH developed a clean and cost-efficient periodate synthesis at BDD. They focused on conducting oxidation at boron-doped diamond anodes, which are durable, metal-free, and nontoxic. Their work is currently published in the research journal, Angewandte Chemie International Edition.

The research team initiated their research with cyclic voltammetry, which suggested a hydroxyl radical based mechanism, which is well known for BDD anodes. More so, common alkali iodides were used as the commercial source and alkaline conditions were chosen to favor a high current efficiency and the solubility of iodine. Further, the use of toxic anti-reducing agents was avoided by using a Nafion membrane. Ultimately, the process was scaled up into a flow electrolysis.

The authors reported that under the working conditions they adopted, heat generation was moderate thereby contributing to an energy-efficient process and a yield of 94%. Overall, it was established that the avoidance of lead dioxide ultimately lowered the cost of purification and quality assurance. All in all, the direct electrochemical synthesis of periodate from common iodides was established at a BDD anode.

In summary, the study presented a direct and cost-efficient electrochemical synthesis of periodate from iodide, which is less costly and relies on a readily available starting material. Remarkably, the conventional use of nondurable metal-based electrodes, in particular lead dioxide, was hereby avoided altogether. In a statement to Advances in Engineering, Professor Siegfried R. Waldvogel emphasized that their presented electrochemical approach will promote the use of periodate in several fields where toxic heavy metals are considered to be critical. Additionally, he further highlighted that the presented method will accelerate future research in the field of hypervalent iodic species.

About the author

Dr Kai Donsbach is Chief Technology Officer at PharmaZell GmbH, Germany. Prior to this appointment, he was Site Manager for Patheon and DSM in Linz, Austria, and Project and Production Manager for Boehringer Ingelheim in Ingelheim, Germany and in Petersburg, USA.

He graduated from the Johannes Gutenberg University, Mainz with a Doctoral thesis in Organic Synthesis and Immunology in 2000. In 1993-94 he received a scholarship by the DAAD to stay at UCI, Irvine.

About the author

Sebastian Arndt is a postdoctoral researcher in the group of Prof. Dr. S. R. Waldvogel where he is conducting research on electrochemical synthesis and recycling processes. He received his PhD in 2018 from the University of Heidelberg working in the field of homogeneous gold-catalysis under the supervision of Prof. Dr. A. S. K. Hashmi. In collaborations, he visited the groups of Prof. Dr. M. Lautens at Toronto University, Prof. Dr. M. Suginome at Kyoto University, and Dr. C. Hyland at Wollongong University.

About the author

Siegfried R. Waldvogel studied chemistry in Konstanz and received his PhD in 1996 from University of Bochum/Max-Planck Institute for Coal Research with Prof. Dr M. T. Reetz as supervisor. After post-doctoral research at Scripps Research Institute in La Jolla, CA (Prof. Dr J. Rebek, Jr), he started his own research career in 1998 at University of Münster. After his professorship in 2004 at University of Bonn, he became a full professor for organic chemistry at Johannes Gutenberg University Mainz in 2010.

His research interests are novel electro-organic trans-formations including bio-based feedstock from electrosynthetic screening to scale-up. In 2018, he co-founded ESy-Labs GmbH, which provides custom electrosynthesis and contract R&D.

About the author

Dominik Weis received his B.Sc. degree in chemistry from Johannes Gutenberg University Mainz working on electrochemical synthesis of periodate under the supervision of Prof. Dr. S. R. Waldvogel.

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Reference

Sebastian Arndt, Dominik Weis, Kai Donsbach, and Siegfried R. Waldvogel. The “Green” Electrochemical Synthesis of Periodate Angewandte Chemie International Edition 2020, volume 59; page 8036 –8041.

Go To Angewandte Chemie International Edition

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