Understanding of the Oxidation Behavior of Benzyl Alcohol by Peroxymonosulfate via Carbon Nanotubes Activation
Understanding of the Oxidation Behavior of Benzyl Alcohol by Peroxymonosulfate via Carbon Nanotubes Activation
复制标题
通过碳纳米管活化了解过一硫酸盐对苯甲醇的氧化行为
DOI：
10.1021/acscatal.9b05273
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发表时间：
2020-03-20
期刊：
影响因子：
12.9
通讯作者：
Liu, Shaomin
中科院分区：
文献类型：
--
作者：
Li, Jiaquan;Li, Mengting;Liu, Shaomin
苯甲醇选择性氧化制苯甲醛是合成化学中的一个重要研究课题。过氧化单硫酸盐（PMS）是一种廉价、稳定、易溶的固体氧化剂，在有机氧化反应中具有广阔的应用前景。在此，我们报告的催化PMS激活通过碳纳米管（CNT）的选择性氧化BzOH在温和的条件下，没有其他添加剂。在修饰的碳纳米管上，BzH的产率显著提高，选择性超过80%，本论文通过实验研究和理论探索，对自由基氧化法制备O-碳纳米管，以及O-碳纳米管的催化功能进行了较为全面的研究。为了了解碳纳米管上不同的表面氧物种对PMS的活化作用，进行了密度泛函理论（DFT）计算，以研究PMS在各种碳纳米管上的吸附行为。亲电氧被确定为电子捕获剂，通过O-O键断裂形成SO_5中心点自由基和SO_4中心点自由基来激活PMS。亲核羰基还可以诱导氧化还原循环以产生（OH）-O-中心点和SO 4中心点自由基，但酚羟基具有抗氧化功能，阻碍自由基过程。碳催化辅助PMS活化可为醇选择氧化成醛或酮提供一种廉价的方法。从这一基础性研究中获得的见解可以进一步应用于通过选择性氧化进行的其他有机合成。
Selective oxidation of benzyl alcohol (BzOH) into benzaldehyde (BzH) is very important in synthetic chemistry. Peroxymonosulfate (PMS) is a cheap, stable, and soluble solid oxidant, holding promise for organic oxidation reactions. Herein, we report the catalytic PMS activation via carbon nanotubes (CNTs) for the selective oxidation of BzOH under mild conditions without other additives. A remarkable promotion of BzH yield with a selectivity over 80% was achieved on modified CNTs, i.e., O-CNTs via the radical oxidation process, and the oxygen functionalities for catalysis were comprehensively investigated by experimental study and theoretical exploration. To understand the different surface oxygen species on CNTs for the activation of PMS, density functional theory (DFT) calculations were performed to investigate the adsorption behavior of PMS on various CNTs. The electrophilic oxygen was identified as the electron captor to activate PMS by O-O bond cleavage to form SO5 center dot- and SO4 center dot- radicals. The nucleophilic carbonyl groups can also induce a redox cycle to generate (OH)-O-center dot and SO4 center dot- radicals, but phenolic hydroxyl groups impede the radical process with antioxidative functionality. The carbocatalysis-assisted PMS activation may provide a cheap process for the selective oxidation of alcohols into aldehydes or ketones. The insight achieved from this fundamental study may be further applied to other organic syntheses via selective oxidation.