Jiang Chen-Chen, Li Xiao-Chong, Fan Jian-Ang, Fu Jia-Ying, Huang-Fu Xu-Nan, Li Jia-Jie, Zheng Ju-Fang, Zhou Xiao-Shun, Wang Ya-Hao
Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China.
Analyst. 2022 Mar 28;147(7):1341-1347. doi: 10.1039/d2an00054g.
The electroreductive cleavage of carbon-halogen bonds has attracted increasing attention in both electrosynthesis and pollution remediation. Herein, by employing the electrochemical shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) technique, we have successfully investigated the electroreductive dehalogenation process of aryl halides with the thiol group on a smooth Au electrode in aqueous solution at different pH values. The obtained potential-dependent Raman spectra directly reveal a mixture of the reduction products 4,4'-biphenyldithiol (BPDT) and thiophenol (TP). The conversion ratios of the C-Cl and C-Br bonds at pH = 7 are 37% and 55%, respectively. Furthermore, quantitative analysis of the intensity variations of (C-Cl), (C-Br) and aromatic (CC) stretching modes suggests electroreductive dehalogenation both direct electron transfer reduction and electrocatalytic hydrodehalogenation. Molecular evidence for the C-C cross coupling process through TP reaction with benzene free radical intermediates is found at negative potentials, which leads to the increasing selectivity of biphenyl products.
