1,8-Dichloroanthraquinone is prepared by the reaction of 1-chloroanthracene-9,10-dione and 2-chloroanthracene-9,10-dione. The steps are as follows:
80 L of the mother liquors obtained according to Example 1a and 40 L of the mother liquors obtained according to Example 1b are combined in a 250 L enamel kettle and heated to 100℃. 12 L of a 10% strength aqueous sodium chlorate solution are fed in at a uniform rate at this temperature in the course of 4 hours, while stirring at 30 - 40 revolutions per minute with an anchor stitter. The mixture is stirred for a further 2 hours at 100℃. and filtered at 80℃. through a filter press, the material on the filter is washed with hot water until the filtrate gives a neutral reaction and the filter cake is dried. 1,8-dichloroanthraquinone are obtained.
