TEMPO-Derived Hybrid for Heterogeneous Electrocatalytic Oxidation of Alcohols to Carbonyl Compounds

Abstract

Molecular electrocatalysis has emerged as a cutting-edge approach for energy storage and conversion. In organic synthesis, it offers eco-friendly alternatives to traditional redox methods. However, improving the efficiency and performance of molecular catalysts remains a key challenge. This study presents the synthesis of NTDA-β-alanine-tethered TEMPO (2,2,6,6-tetramethylpyridinyl-N-oxyl), which achieves efficient ex situ noncovalent immobilization over MWCNTs. This approach provides superior control over catalyst properties, enhances stability, and allows for easier regeneration or modification compared to in-situ methods. The method efficiently oxidizes various aromatic, aliphatic, and optically active alcohols like terpenoids, while preserving the chiral integrity of optically active compounds. Additionally, the study explores the role of steric hindrance in oxidation, shedding light on the link between molecular structure and catalytic performance. It highlights the immobilized catalyst's remarkable reproducibility and high turnover frequencies (TOF), as confirmed through chronoamperometric analysis. Furthermore, the catalyst displayed excellent conversion when exposed to bulk electrocatalysis. This study presents an effective electrocatalytic method that employs ex-situ immobilization to improve catalyst performance, stability, reproducibility, and adaptability, promoting more sustainable and precise organic transformations. © 2025 Elsevier B.V., All rights reserved.