The oxidation of 2,3,6-trimethylphenol with molecular oxygen produced 2,3,5-trimethyl-1,4-benzoquinone (TMBQ) by using CuCl₂ as the catalyst, however, it led to coupling when the catalyst was replaced by Cu(OAc)₂. To gain deeper insight into the difference of the catalytic mechanism, the in-depth studies were carried out by controlled experiments such as adding CuCl₂ at different times into the system initially catalyzed by Cu(OAc)₂ and by using the electron paramagnetic resonance (EPR). In controlled experiments, the oxygenation reaction is dominant when adding CuCl₂. In EPR, the phenoxyl radical was detected in the Cu(OAc)₂ catalysis system, but not found in the CuCl₂ system. All these results suggested that the rate of oxygenation catalyzed by CuCl₂ was much faster than that of coupling, which was reinforced by the kinetics experiments. The attacking of activated molecular oxygen by CuCl₂ on the phenoxyl radical is proposed as the major route to obtain TMBQ. In the process, the interaction existed between Cl and H-atom at para-position to help eliminating proton by DFT calculation. Moreover, the CuCl₂ was inactivated by multidentates ligands suggested the coordination sites on the catalyst should play key roles in oxygenation.

以分子氧氧化2,3,6-三甲基苯酚以CuCl ₂为催化剂生成2,3,5-三甲基-1,4-苯醌（TMBQ），但是当催化剂被取代时会导致偶联。 Cu（OAc）₂。为了更深入地了解催化机理的差异，我们通过受控实验进行了深入研究，例如在不同时间将CuCl ₂添加到最初由Cu（OAc）₂催化的体系中，并利用电子顺磁共振（ EPR）。在对照实验中，当添加CuCl ₂时，氧合反应占主导。在EPR中，在Cu（OAc）₂催化系统中检测到苯氧基自由基，但在CuCl _2中未发现系统。所有这些结果表明，CuCl ₂催化的氧合速率比偶合的快得多，这通过动力学实验得到了加强。提出CuCl ₂对苯氧基自由基的活化分子氧的攻击是获得TMBQ的主要途径。在此过程中，Cl和H原子之间在对位存在相互作用，以帮助通过DFT计算消除质子。此外，CuCl ₂被多齿配体灭活，表明催化剂上的配位点应在氧化中起关键作用。