Abstract: A series of 6-substituted phenyl-2-(3í-substituted phenyl pyridazin-6í-yl)-2, 3, 4, 5- tetrahydropyridazin-3-ones has been synthesized. An appropriate aromatic hydrocarbon reacts with succinic anhydride in presence of AlCl3 to yield β-aroyl propionic acid. The corresponding acid was cyclized with hydrazine hydrate to give 6-(substituted aryl)-2, 3, 4, 5- tetrahydro-3-pyridazinone, which was heated on steam bath with phosphorus (V) ...