Chloranil: p-Nitroaniline Chlorinated, Reduced with Tin and Oxidised with Chlorate (Thorpe 1913)

Chloranil, tetrachloro-p-benzoquinone, is a quinone carrying four chlorine atoms, used to oxidise colourless leuco bases into dyes. Thorpe's Dictionary of Applied Chemistry (1913) gives Witt and Toeche-Mittler's method, which gave the best results: chlorinate p-nitroaniline with potassium chlorate in hydrochloric acid to a dichloronitroaniline, then reduce it with tin in boiling hydrochloric acid and oxidise it with more chlorate to chloranil, 11 g from 12 g. The glassware, the water for the chlorate and the filtering are ours. Source: Thorpe, Dictionary of Applied Chemistry vol. IV (1913), QUINONES, p. 494. Picture: that page.