Acetoacetanilide: Aniline in Ether with Diketene Added Slowly (Gleason, Standard Oil Development, US 2,174,239)

Diketene and aniline join into acetoacetanilide, the coupling component of Hansa yellow, but neat they react so violently that the product is poor. Gleason tamed the reaction by diluting both in ether and adding the diketene slowly; the anilide simply crystallises out. Result: crystals of acetoacetanilide. Source: Gleason, US 2,174,239 (Standard Oil Development, 1939). Not given: yield. Picture drawn by Youblob.