Electrochemical chlorination of aromatic compounds: comparison between batch and flow reactions

Aromatic halides are essential molecules in agrochemical, medicine and advanced materials [1]. The most classical method to synthetize them, is through the electrophilic substitution of aromatic compounds using halogenated sources which are low atom-economy (such as NBS or NCS) or not environmentally friendly (like Br2 or Cl2) reagents. Organic electrochemistry is a powerful tool that can be used to overcome these limitations since its application requires greener halogenated sources like alkali metal halides [2]. Even if electrochemical halogenation reactions, especially chlorination ones, have been studied for many years, they still suffer of a limited substrates scope. Indeed, electron-poor systems show less reactivity compared to the electron-rich ones and a possible polymerization of the aromatic compounds affects heavily the product yield [3] In this framework, we decided to explore the advantages of the flow chemistry in the electrochemical chlorination of 1,2 dimethylimidazole (1) and 1,3-dimethoxybenzene (2) as reported in Figure 1. The comparison between batch and flow chemistry can lead to an enhancement of the yields along with the productivity for the in flow process. Further chlorination reactions of aromatic and heteroaromatic compounds are still in progress and will be presented.