Selective synthesis of meta-phenols from bio-benzoic acids via regulating the adsorption state

Xinze Du; Yumei Liu; Huixiang Li; Shenglin Liu; Xiaojun Shen

doi:10.1016/j.isci.2023.107460

Selective synthesis of meta-phenols from bio-benzoic acids via regulating the adsorption state

iScience. 2023 Jul 25;26(8):107460. doi: 10.1016/j.isci.2023.107460. eCollection 2023 Aug 18.

Authors

Xinze Du^{1

2}, Yumei Liu³, Huixiang Li¹, Shenglin Liu¹, Xiaojun Shen^{1

4}

Affiliations

¹ State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
² University of Chinese Academy of Sciences, Beijing 100049, China.
³ Department of Chemistry, School of Chemical Engineering, Dalian University of Technology, Dalian 116023, China.
⁴ Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China.

Abstract

Phenols are important building blocks widely applied in many fields. The pronounced orientational effect of the phenolic hydroxyl group makes achieving selective synthesis of meta-phenols challenging. Accessing meta-phenols needs lengthy synthetic sequences. Herein, we first developed a heterogeneous CO₂-mediated CeO₂-5CuO catalyst for decarboxylative oxidation of benzoic acids with a more than 80% selectivity to meta-phenols. This technology is based on a traceless directing group relay method. The CeO₂-CuO catalysts with different Ce/Cu ratios exhibited controllable reaction selectivity between decarboxylation and decarboxylative oxidation. Spectroscopy experiments and computational studies showed the adsorption state of benzoic acid was found to be crucial for subsequent reaction pathways. The moderate adsorption on CO₂-mediated CeO₂-5CuO catalyst contributes to the distinct selectivity of phenol. Furthermore, the paddlewheel intermediate facilitates the synthesis of meta-phenols from benzoic acids. This traceless directing group method would promote the development of useful one-pot meta-substituted phenols from bio-based benzoic acids.

Keywords: Chemistry; Green chemistry; Organic chemistry.