Electrosynthesis involves transferring charge between two electrodes to promote chemical reactions by applying potential. The modes of controlling the current and potential can affect the reaction mechanism, product distribution and yields, and add a control factor for reaction optimization. In this Synopsis, theoretical discussion is applied to specific case studies from the literature to illustrate methods of adjusting and tracking electrical parameters for the optimization and monitoring of electroorganic reactions.

Organic electrosynthesis is an increasingly popular tool for driving and probing redox reactions. Recent advances in this field often employ an electrocatalyst to enhance the selectivity and efficiency of electrochemical reactions. A laboratory experiment was developed to introduce students to relevant mechanistic techniques in electrochemistry for analysis of electrocatalytic reactions using aminoxyl-catalyzed alcohol oxidation as a case study. This lab activity employs cyclic voltammetry for qualitative assessment of catalytic turnover prior to introducing students to chronoamperometry, an underutilized technique that facilitates quantitative determination of the rate of catalysis. Students identify and rationalize the important features of a reversible electron transfer and a catalytic reaction in a cyclic voltammogram, probe the origin of scan rate effects on these traces, and calculate turnover frequency using a series of chronoamperograms. The method employs safe and readily available reagents: basic aqueous buffer solution, alcohol substrate, and an inexpensive organic aminoxyl catalyst. Student data presented herein were obtained from a course attended by undergraduate students, graduate students, and pharmaceutical chemists.

Herein, the insights gleaned from mechanistic studies of aminoxyl catalyzed oxidation of alcohols and aldehydes were used for fabrication of a gas phase sensor for ethanol and acetaldehyde. This electrochemical...

Blood alcohol concentration (BAC) is the indicator of alcohol intoxication, and its measurement has emerged as the most common analytical procedure requested by law enforcement. Due to its volatility, ethanol vapor can be detected in breath, and its vapor concentration is proportional to BAC. Currently available instrumentation used for breath alcohol content (BrAC) analysis include gas chromatography (GC) and GC coupled with mass spectrometry, infrared (IR) spectroscopy, and fuel cell based electrochemical sensors. GC and IR spectroscopy devices have some drawbacks such as size, initial cost, and operational expense. Electrochemical sensors are capable of miniaturization and are available as portable and handheld breathalyzers. However, the lack of a single use and disposable sensing element, resulting memory effect and the need for frequent recalibration is the main drawback of currently available electrochemical breathalyzers. There have been few attempts at designing a sensing element to improve the current methods of alcohol detection by electrochemical techniques, all relying on enzymatic alcohol oxidation.1 Herein, we report a proof-of-concept non-enzymatic breathalyzer, harnessing the unique catalytic activity of the aminoxyl radical/oxoammonium redox couple toward alcohol oxidation.2 The relatively low redox potentials of aminoxyls, the mild conditions required for use, and their selective interactions with ethanol are their advantages compared to currently available Pt based breathalyzers. Our functional sensing element consists of a screen-printed electrode in which the graphene oxide-based working electrode is modified with aminoxyl derivatives, of which 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl benzoate (TMB) was the most efficient derivative. Exposing this modified electrode to simulated breath that contains ethanol, while applying the required potential for oxidation of the aminoxyl radical, generates an electrocatalytic current proportional to the ethanol concentration in the breath. These simple, sensitive, durable, and inexpensive electrodes may contribute to the development of a single-use reliable ethanol sensor for personal or law enforcement applications. Heikenfeld, J.; Jajack, A.; Rogers, J.; Gutruf, P.; Tian, L.; Pan, T.; Li, R.; Khine, M.; Kim, J.; Wang, J.; Kim, J. Wearable Sensors: Modalities, Challenges, and Prospects. Lab Chip 2018, 18, 217. Nutting, J. E.; Rafiee, M.; Stahl, S. S. Tetramethylpiperidine N-Oxyl (TEMPO), Phthalimide N-Oxyl (PINO), and Related N-Oxyl Species: Electrochemical Properties and Their Use in Electrocatalytic Reactions. Chem. Rev. 2018, 118, 4834.