Facile p-toluenesulfonic acid-promoted para-selective monobromination and chlorination of phenol and analogues

para-Regioselective bromination of phenol and analogues, promoted by p-toluenesulfonic acid, is achieved in high to excellent yields at room temperature with N-bromosuccinimide. Chlorination with N-chlorosuccinimide and catalysed by p-toluenesulfonic acid also gives para-chlorinated phenol analogues in good yields at room temperature.

para-Bromination of phenol, promoted by p-toluenesulfonic acid, is achieved in excellent yields at room temperature with N-bromosuccinimide. p-Toluenesulfonic acid is also effective as a promoter of para-chlorination with N-chlorosuccinimide.