8-Hydroxyquinoline → Aluminium tri(quinolin-8-olate)

Aluminum stearate, Al[CH3(CH2)16CO2]3, (10.0 g, Fisher Scientific Co., Pittsburgh, Pa., technical grade) was placed in a 250 mL round bottomed flask equipped with a magnetic stir bar and a reflux condenser. Toluene (50 mL) was added to give a white slurry. Separately, a 6.0 g sample of 8-hydroxyquinoline (41.3 mmol) was dissolved in 150 mL of toluene and the solution was gravity filtered through a coarse glass frit into the reaction flask. This removed an insoluble minor impurity found in the 8-hydroxyquinoline. After the addition of the 8-hydroxyquinoline to the aluminum stearate-toluene solution, the reaction flask was heated to reflux by means of an electric heating mantle. As the reaction warmed, but prior to refluxing, a large quantity of a fine yellow solid precipitated. The reaction mixture was refluxed for approximately 72 hours, cooled, and filtered. The yellow filter cake was washed sequentially with two 50 mL portions of toluene and two 50 mL portions of petroleum ether. After vacuum drying, the filter cake provided 5.4 g of tris(8-quinolinolato)aluminum as fine yellow needles. An 1H-NMR of the product precipitated from the toluene reaction mixture showed no significant resonances other than those of the desired product.