In a 500-ml. round-bottomed three-necked flask fitted with a reflux condenser, a dropping funnel, and a mercury-sealed stirrer (Note 1) is placed a solution of 46 g. (0.5 mole) of dry aniline in 125 ml. of pure dry benzene. Stirring is started, and a solution of 42 g. (0.5 mole) of ketene dimer (p. 508) in 75 ml. of pure dry benzene is added dropwise over a period of 30 minutes. The reaction mixture is then heated under reflux on the steam bath for 1 hour. After the major portion of the benzene has been removed by distillation from the steam bath, the remainder is removed under reduced pressure. The residue is dissolved in 500 ml. of hot 50% aqueous ethanol from which the acetoacetanilide separates on cooling. The mixture is cooled to 0° before filtration. A second crop of crystals can be obtained by adding 250 ml. of water to the mother liquor and cooling again (Note 2). The total yield of product, m.p. 82–83.5°, is 65 g. (74%). Further purification by recrystallization from 300 ml. of 50% ethanol yields 55 g. of a product that melts at 84–85°.