Non-Transition-Metal-Mediated Electrochemical Oxidations of Alcohols to Aldehydes and Ketones

Abstract

Given the central role of carbonyl compounds in chemical synthesis, considerable effort has been devoted to developing more sustainable and efficient methods for accessing aldehydes and ketones at both laboratory and industrial scales. In recent years electrochemical oxidations of alcohols have seen increased interest in academic settings as a method for removing the toxic and environmentally damaging reagents, such as transition-metal catalysts, found in classical alcohol oxidations. This graphical review aims to deliver a concise summary of the current synthetic electrochemical methods available and place them in the context of the traditional oxidations they aim to replace.

Key words

electrosynthesis - TEMPO - halides - oxidation - alcohols - ketones - aldehydes

Biosketches

Kevin Lam obtained his Ph.D. in Medicinal and Synthetic Organic Chemistry from the Catholic University of Louvain (UCLouvain), Belgium, in 2010 under the supervision of Professor István Markó, where he developed a new radical-based deoxygenation reaction now known as the Lam–Markó reaction. Following his doctorate, he joined the University of Vermont, USA, as a postdoctoral researcher, applying analytical and physical electrochemistry alongside spectroscopy to investigate the redox behaviour of organometallic complexes. In 2013, he was appointed as an assistant professor at Nazarbayev University in Astana, Kazakhstan, where he established a new research programme in molecular electrochemistry. He later joined the University of Greenwich in 2017, becoming Reader in Synthetic Electrochemistry, and was promoted to a full professor in 2023. In 2025, he became Head of C-SMART (Centre for Synthesis, Materials, Analytics and Research in Translational Science). Kevin’s research focuses on sustainable electrosynthesis: the development of safe, green, and scalable electrochemical methodologies for generating highly reactive intermediates. His group has pioneered novel flow-electrosynthetic platforms that bridge laboratory discovery and industrial implementation, with applications across pharmaceutical, fine chemical, and materials sectors. Collaborations with partners such as GSK, AstraZeneca, and Johnson & Johnson exemplify the translational reach of his work.

Conall Molloy was born in Dublin, Ireland, and completed his bachelor’s degree in general chemistry at Trinity College Dublin, where his dissertation focused on the synthesis of ammonium catalysts for PET recycling, contributing to sustainable solutions for plastic waste. In 2024 Conall started his Ph.D. in collaboration with GSK on the development of novel electrochemical methods for the synthesis of aldehydes. He also really likes monkeys.

The oxidation of alcohols to aldehydes and ketones remains a fundamental transformation in organic chemistry, underpinning both fine-chemical synthesis and large-scale industrial manufacturing. Conventional oxidation methods often rely on stoichiometric reagents or precious-metal catalysts, generating waste and limiting sustainability. As the demand for greener chemical processes intensifies, the development of environmentally benign oxidation strategies has become a central objective in modern synthetic research.

Electroorganic synthesis has emerged as a powerful alternative, replacing traditional redox reagents with electric current as a clean, tuneable, and inherently sustainable oxidant. This approach eliminates hazardous oxidants while enabling precise control over potential, selectivity, and reaction kinetics. In particular, the electrochemical oxidation of primary and secondary alcohols has gained prominence as a versatile platform for sustainable oxidation chemistry. Among various strategies, mediated (indirect) electrooxidation has proven especially effective: instead of direct substrate oxidation at the electrode, a redox-active mediator is electrochemically generated to perform the oxidation under milder, more selective conditions.

Nitroxyl radicals, halides, and sulfides have emerged as leading mediator systems, each offering distinct mechanistic profiles, operational advantages, and environmental considerations. Despite substantial advances, challenges persist regarding scalability, generality, and mechanistic understanding. This graphical review critically examines the evolution of mediator-enabled electrochemical alcohol oxidation, summarising key mechanistic insights, highlighting landmark studies, and identifying the remaining hurdles and future directions necessary for broad and practical adoption.

Figure 1 Nitroxyl-mediated electrochemical oxidation of alcohols to aldehydes and ketones, part 1[1`] [b] [c] [d] [e] [f] [g] [h]

Figure 2 Nitroxyl-mediated electrochemical oxidation of alcohols to aldehydes and ketones, part 2[2`] [b] [c] [d] [e] [f] [g] [h]

Figure 3 Halide-mediated oxidations, part 1[3`] [b] [c] [d] [e] [f] [g] [h]

Figure 4 Halide-mediated oxidations, part 2[4`] [b] [c] [d] [e] [f] [g]

Figure 5 Halide-, nitrate- and sulfide-mediated oxidations of alcohols[5`] [b] [c] [d] [e] [f] [g] [h]

Conflict of Interest

The authors declare no conflict of interest.

• References

• 1a Anelli PL, Biffi C, Montanari F, Quici S. J. Org. Chem. 1987; 52: 2559
• 1b Hoover JM, Stahl SS. J. Am. Chem. Soc. 2011; 133: 16901
• 1c Semmelhack MF, Chou CS, Cortes DA. J. Am. Chem. Soc. 1983; 105: 4492
• 1d Rafiee M, Miles KC, Stahl SS. J. Am. Chem. Soc. 2015; 137: 14751
• 1e Tsunaga M, Iwakura C, Tamura H. Electrochim. Acta 1973; 18: 241
• 1f Bailey WF, Bobbitt JM, Wiberg KB. J. Org. Chem. 2007; 72: 4504
• 1g Bobbitt JM, Bartelson AL, Bailey WF, Hamlin TA, Kelly CB. J. Org. Chem. 2014; 79: 1055
• 1h Kishioka S, Ohsaka T, Tokuda K. Chem. Lett. 1998; 27: 343
• 2a Schroeder CM, Politano F, Ohlhorst KK, Leadbeater NE. RSC Adv. 2023; 13: 25459
• 2b Demizu Y, Shiigi H, Oda T, Matsumura Y, Onomura O. Tetrahedron Lett. 2008; 49: 48
• 2c Das A, Stahl SS. Angew. Chem. Int. Ed. 2017; 56: 8892
• 2d Li S, Wang S, Wang Y, He J, Li K, Gerken JB, Stahl SS, Zhong X, Wang J. Nat. Commun. 2025; 16: 266
• 2e Place SD, Kavanagh P. Electroanalysis 2024; 36: e202300195
• 2f Palmisano G, Ciriminna R, Pagliaro M. Adv. Synth. Catal. 2006; 348: 2033
• 2g Nutting JE, Rafiee M, Stahl SS. Chem. Rev. 2018; 118: 4834
• 2h Ciriminna R, Ghahremani M, Karimi B, Pagliaro M. ChemistryOpen 2017; 6: 5
• 3a Shono T, Matsumura Y, Hayashi J, Mizoguchi M. Tetrahedron Lett. 1979; 20: 165
• 3b Yoshikawa M, Murakami T, Yagi N, Murakami N, Yamahara J, Matsuda H, Maeda H, Ohmori H. Chem. Pharm. Bull. 1997; 45: 570
• 3c Okimoto M, Takahashi Y, Nagata Y, Sasaki G, Numata K. ChemInform 2005; 36
• 3d Okimoto M, Yoshida T, Hoshi M, Chiba T, Maeo K. Synth. Commun. 2011; 41: 3134
• 3e Moriyama K, Takemura M, Togo H. J. Org. Chem. 2014; 79: 6094
• 3f Yoshida J, Nakai R, Kawabata N. J. Org. Chem. 1980; 45: 5269
• 3g Maekawa H, Ishino Y, Nishiguchi I. Chem. Lett. 1994; 23: 1017
• 3h Raju T, Manivasagan S, Revathy B, Kulangiappar K, Muthukumaran A. Tetrahedron Lett. 2007; 48: 3681
• 4a Yamamoto K, Inoue T, Hanazawa N, Kuriyama M, Onomura O. Tetrahedron Green Chem. 2023; 1: 100010
• 4b William JM, Kuriyama M, Onomura O. Adv. Synth. Catal. 2014; 356: 934
• 4c Yamamoto K, Toguchi H, Kuriyama M, Watanabe S, Iwasaki F, Onomura O. J. Org. Chem. 2021; 86: 16177
• 4d Barysevich MV, Aniskevich YM, Hurski AL. Synlett 2021; 32: 1934
• 4e Bosco AJ, Lawrence S, Christopher C, Radhakrishnan S, Joseph Rosario AA, Raja S, Vasudevan D. J. Phys. Org. Chem. 2015; 28: 591
• 4f Medici A, Pedrini P, De Battisti A, Fantin G, Fogagnolo M, Guerrini A. Steroids 2001; 66: 63
• 4g Sommer F, Kappe CO, Cantillo D. Synlett 2022; 33: 166
• 5a Yamamoto K, Kikuchi N, Hamamizu T, Yoshimatsu H, Kuriyama M, Demizu Y, Onomura O. ChemElectroChem 2019; 6: 4169
• 5b Christopher C, Lawrence S, Anbu Kulandainathan M, Kulangiappar K, Easu Raja M, Xavier N, Raja S. Tetrahedron Lett. 2012; 53: 2802
• 5c Shono T, Matsumura Y, Mizoguchi M, Hayashi J. Tetrahedron Lett. 1979; 20: 3861
• 5d Matsumura Y, Yamada M, Kise N, Fujiwara M. Tetrahedron 1995; 51: 6411
• 5e Molloy C, Kaltenberger S, Edwards L, Wheelhouse KM. P, Lam K. Chem. Sci. 2025; 16: 20286
• 5f Yamamoto K, Kuriyama M, Onomura O. Isr. J. Chem. 2024; 64: e202300068
• 5g Lian F, Xu K, Zeng C. Chem. Rec. 2021; 21: 2290
• 5h Bégué J.-P, Bonnet-Delpon D, Crousse B. Synlett 2004; 18

Publication History

Received: 04 November 2025

Accepted after revision: 12 January 2026

Accepted Manuscript online:
12 January 2026

Article published online:
29 January 2026