7.51 Parts of 2,5-di(p-chloroanilino)terephthalic acid obtained in Example 13, 79 parts of nitrobenzene, 6 parts of benzoyl chloride and 1.65 parts of quinoline were charged into a 200-ml flask of stainless steel, and maintained at 200° C. for 5 hours. When the mixture was temperature-increased up to about 180° C., hydrochloric acid gas was generated and the intramolecular-dehydration reaction was initiated. The reaction mixture was cooled to 110° C., and then 2.27 parts of 30% sodium hydroxide was dropwise added to decompose an excess of benzoyl chloride. Then, the reaction mixture was filtered while it was hot, washed with methanol, washed with water and dried to give 6.37 parts (92.8% of the theoretical yield) of 2,9-dichloroquinacridone.
