Sulfuric Acid → Fuming sulfuric acid

Participants

Reaction Conditions

Reaction Steps

111.5 parts of 1-aminoanthraquinone are added to 660 parts of o-dichlorobenzene. The mixture is heated to 100°-103° C. and then 74.6 parts of chlorine gas are introduced above the surface of the solution. When the addition of chlorine is complete, 8 parts of bromine are added. The reaction mixture is stirred for 1 hour at 100° C., allowed to cool to room temperature, and then 548 parts of 100% sulfuric acid are added dropwise at 20°-30° C. over 30 minutes. The batch is stirred for 1 hour and the o-dichlorobenzene phase is then separated. Then 72.5 parts of 66% oleum are added to the sulfuric acid phase, which contains a mixture of 1-amino-2,4-dichloroanthraquinone, 1-amino-2-bromo-4-chloroanthraquinone and 1-amino-2,4-dibromoanthraquinone, to give an oleum concentration of c. 7%, and then 52.4 parts of boric acid are added such that the temperature does not exceed 60° C. The reaction mixture is then heated for 1 hour to 100° C. and stirred for 1 hour at this temperature. The temperature is then raised to 137°-140° C. over 30 minutes. The reaction mixture is stirred for 3 hours at this temperature and then cooled to 110° C. 431 parts of water are then added such that the temperature of the mixture is about 130° C. and the concentration of sulfuric acid is about 60%. After stirring for 1 hour at 130° C., the reaction mixture is cooled to 50° C. and filtered at this temperature. The filter residue is washed with 300 parts of 60% sulfuric acid then with water, and vacuum dried at 90°-100° C., to give 125.7 parts of a mixture comprising 86.7% of 1-amino-2-chloro-4-hydroxyanthraquinone and 7.3% of 1-amino-2-bromo-4-hydroxyanthraquinone. This corresponds to a yield of 85.5% of theory.

Provenance & Evidence