One-step highly selective oxidation of p-xylene to 4-hydroxymethylbenzoic acid over Cu-MOF catalysts under mild conditions
One-step highly selective oxidation of p-xylene to 4-hydroxymethylbenzoic acid over Cu-MOF catalysts under mild conditions
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温和条件下 Cu-MOF 催化剂一步高选择性氧化对二甲苯生成 4-羟甲基苯甲酸
DOI：
10.1016/j.mcat.2019.110542
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发表时间：
2019-10-01
影响因子：
4.6
通讯作者：
Wang, Jiaqiang
中科院分区：
文献类型：
--
作者：
Li, Ying;Wu, Mingzhu;Wang, Jiaqiang
对二甲苯是一种廉价的工业原料，主要用于合成对苯二甲酸。然而，对二甲苯很少被氧化成其他含氧的衍生物。另一方面，目前合成4-羟甲基苯甲酸的方法存在反应步骤多、反应时间长、温度高、压力大、选择性低等缺点。在温和的条件下，以CuMOF为催化剂，乙腈为溶剂，30%H_2O_2为氧化剂，对二甲苯直接氧化合成4-羟甲基苯甲酸。在30℃下反应5h，4-羟甲基苯甲酸的选择性很高(99.2%)，对二甲苯的底物转化率为85.5%。快速热催化剂过滤实验证明，CuMOF是一种多相催化剂。它可以重复使用三次而不会失去活性。在优化条件下，实验放大15倍，对羟甲基苯甲酸的选择性和对二甲苯的转化率分别为97.6%和84.8%。过氧化氢的利用率也高达92.0%。结合X射线衍射、红外光谱、X射线光电子能谱分析，提出了反应机理。所有数据表明，在温和的条件下，CuMOF在高选择性氧化稳定的C-H合成含两个不同C-O带的高附加值化合物方面具有很大的潜力。这也为对二甲苯的使用开辟了一条新的途径。
p-Xylene, a cheap industrial raw material, is mainly used to synthesize terephthalic acid. However, p-xylene was oxidized rarely to other oxygen-containing derivatives. On the other hand, current methods for synthesis of 4-hydroxymethylenzoic acid suffer from multistep reactions, long reaction time, high temperature, high pressure, and lower selectivity. In this work, p-xylene was directly oxidized into 4-hydroxymethylbenzoic acid using Cu-MOF as the catalyst, acetonitrile as the solvent, and 30% H2O2 as the oxidant under mild conditions. Very high selectivity (99.2%) of 4-hydroxymethylbenzoic acid and good substrate conversion (85.5%) of p-xylene were achieved at 30 degrees C for 5 h. Fast hot catalyst filtration experiments proved that Cu-MOF acted as a heterogeneous catalyst. It can be reused three times without losing its activity. Under optimized conditions, the selectivity of 4-hydroxymethyl benzoic acid and the conversion of p-xylene were 97.6% and 84.8% even though the experiment was amplified 15-folds. The efficiency of H2O2 was also up to 92.0%. The reaction mechanism was proposed combined with the analysis of XRD, FT-IR and XPS. All data displayed that Cu-MOF shows great potential as a catalyst for highly selective oxidation of stable C-H to high value-added compounds containing two diverse C-O bands under mild conditions. It also opens a new way to use of p-xylene.