Highly Selective Electrocatalytic Reduction of Substituted Nitrobenzenes to Their Aniline Derivatives Using a Polyoxometalate Redox Mediator.
Highly Selective Electrocatalytic Reduction of Substituted Nitrobenzenes to Their Aniline Derivatives Using a Polyoxometalate Redox Mediator.
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DOI：
10.1021/acsorginorgau.2c00047
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发表时间：
2023-02-01
期刊：
影响因子：
--
通讯作者：
Symes, Mark D
中科院分区：
文献类型：
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作者：
Stergiou, Athanasios D;Broadhurst, Daniel H;Symes, Mark D
苯胺和取代苯胺以数吨规模用于生产聚合物、药物、染料和其他重要化合物。通常，这些苯胺是由其相应的硝基苯前体通过在高温下与氢反应而产生的。然而，该路线具有许多缺点，包括需要处理氢气，导致缺乏选择性和/或某些官能团的耐受性的相当苛刻的反应条件，以及可疑的环境可持续性。鉴于此，在室温下，在水性溶剂中，并且不需要使用苛刻的工艺条件，氢气或牺牲试剂的情况下，将硝基苯还原为其苯胺衍生物的路线可能具有巨大的益处。在这里，我们报告了一个高选择性的电催化还原硝基苯到其相应的苯胺，在水溶液中，在室温下工作，不需要使用氢气或牺牲试剂的路线。该方法使用聚氧乙烯酸盐氧化还原介体，其可逆地接受来自阴极的电子并与溶液中的硝基苯反应以将它们还原成相应的苯胺。各种取代的硝基芳烃被探索作为底物，包括那些潜在的竞争性可还原基团和底物，难以通过其他手段选择性地减少。在所有情况下，氧化还原介导的路线的选择性高于在电极上的硝基芳烃底物的直接还原，这表明氧化还原介导的电化学硝基芳烃还原是一个有前途的途径，更可持续的取代苯胺的合成。
Anilines and substituted anilines are used on the multi-ton scale for producing polymers, pharmaceuticals, dyes, and other important compounds. Typically, these anilines are produced from their corresponding nitrobenzene precursors by reaction with hydrogen at high temperatures. However, this route suffers from a number of drawbacks, including the requirement to handle hydrogen gas, rather harsh reaction conditions that lead to a lack of selectivity and/or toleration of certain functional groups, and questionable environmental sustainability. In light of this, routes to the reduction of nitrobenzenes to their aniline derivatives that operate at room temperature, in aqueous solvent, and without the requirement to use harsh process conditions, hydrogen gas, or sacrificial reagents could be of tremendous benefit. Herein, we report on a highly selective electrocatalytic route for the reduction of nitrobenzenes to their corresponding anilines that works in aqueous solution at room temperature and which does not require the use of hydrogen gas or sacrificial reagents. The method uses a polyoxometalate redox mediator, which reversibly accepts electrons from the cathode and reacts with the nitrobenzenes in solution to reduce them to the corresponding anilines. A variety of substituted nitroarenes are explored as substrates, including those with potentially competing reducible groups and substrates that are difficult to reduce selectively by other means. In all cases, the selectivity for the redox-mediated route is higher than that for the direct reduction of the nitroarene substrates at the electrode, suggesting that redox-mediated electrochemical nitroarene reduction is a promising avenue for the more sustainable synthesis of substituted anilines.