An unusual substitution reaction of an aromatic sulfonic group based on 3-carbonyl-4-phenolsulfonic acid

An unusual substitution reaction of an aromatic sulfonic group based on 3-carbonyl-4-phenolsulfonic acid was discovered in a diazo-coupling process. The reaction occurred under mild reaction conditions (pH 8.0–9.0, 0–5 °C, solvent: water) within a short reaction time (1 h). A plausible substitution reaction mechanism by phenol–ketone resonance was proposed.

Graphical abstractAn unusual substitution reaction of an aromatic sulfonic group based on benzophenone was discovered in a diazo-coupling process. Generally, the desulfonation and regioselective substitution of aromatic sulfonic acids are difficult processes, which usually require stoichiometric reducing agents or harsh conditions. In this paper, the reaction occurred under mild conditions (pH 8.0–9.0, 0–5 °C, solvent: water) within a short reaction time (1 h). A plausible substitution reaction mechanism by phenol–ketone resonance was proposed.Figure optionsDownload full-size imageDownload as PowerPoint slide