Developments in the Dehydrogenative Electrochemical Synthesis of 3,3',5,5'-Tetramethyl-2,2'-biphenol.

The symmetric biphenol 3,3',5,5'-tetramethyl-2,2'-biphenol is a well-known ligand building block and is used in transition-metal catalysis. In the literature, there are several synthetic routes for the preparation of this exceptional molecule. Herein, the focus is on the sustainable electrochemical synthesis of 3,3',5,5'-tetramethyl-2,2'-biphenol. A brief overview of the developmental history of this inconspicuous molecule, which is of great interest for technical applications, but has many challenges for its synthesis, is provided. The electro-organic method is a powerful, sustainable, and efficient alternative to conventional synthesis to obtain this symmetric biphenol up to the kilogram scale. Another section of this article is devoted to different process management strategies in batch-type and flow electrolysis and their respective advantages.