From literature, it was described that fluorene can react with NCS and conc. HCl to produce the 2,7-diCl derivative. Please help me understand the mechanism.
According to this paper here
it has been described recently that at very low pH (Ph < 3) Cl2 functions as an active chlorinating agent
In the authors' view the system works by NCS oxidising chloride to chlorine which then provides Cl+ as the chlorinating agent.