. A process for the preparation of tetrachloro-1,4-benzoquinone from hydroquinone in the presence of an aqueous medium containing chlorine and
hydrochloric acid, which comprises the steps of:
providing an aqueous medium containing iron (III) ions as a catalyst, an anionic dispersant, and hydrochloric acid in a concentration of 20 to 37%,
said hydrochloric acid being provided in a 4 to 6 times molar amount based on the total amount of hydroquinone to be added in said process;
dividing said total amount of hydroquinone into space-time yield-improving portions and introducing a first portion of the hydroquinone into said
aqueous medium; introducing 1.5 to 2.0 times the molar amount, based on said total amount hydroquinone, of chlorine as a gas into the aqueous medium
at a temperature of from 20.degree. to 90.degree. C. in a first chlorine addition; adding the remaining portion of hydroquinone; introducing 1.5 to
2.0 times the molar amount, based on said total amount of hydroquinone, of chlorine as a gas in a second chlorine addition; holding the concentration
of the hydrochloric acid in the aqueous medium at 23-25% by addition of water; raising the temperature to 100.degree. to 107.degree. C. while
introducing additional chlorine gas at 1.7 to 2.5 times the total molar amount of hydroquinone in a third chlorine addition; and diluting the aqueous
medium with water to a hydrochloric acid concentration of from 20 to 22%.
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