| Abstract: | A mixture of acridine and a pyrazolone derivative was reacted in the solid state (without solvent). It is proposed that the enol tautomer (the C4‐position) of the pyrazolone derivative attacks the C9‐position of acridine through a nucleophilic reaction resulting in products where the C4‐position of pyrazolone is connected to the C9‐position of acridine. When the reaction of 3‐methyl‐1‐phenyl‐5‐pyrazolone and acridine was carried out at low temperature (25°–50°), the reaction product was obtained even when the majority of the reaction mixture had not melted. The same reaction was also carried out in the presence of an ultrasonic wave at same temperature (25°–50°) and the reaction product was obtained in high yield. Under ultrasonic conditions, the reaction mixture was not melted. However, the interface between 3‐methyl‐1‐phenyl‐5‐pyrazolone and acridine gradually changed from white to black. In this reaction, the dihydroacridine dimer is not obtained. |
