A solution of 40 parts of potassium hydroxide in 60 parts of water is added to a solution of 66 parts of thiophenol in 1,000 parts of dimethylformamide and 171 parts of 2-phenyl-6-chloroanthrapyrimidine are then introduced. The mixture is stirred for 16 hours at room temperature and afterwards for a further hour at 50°-60°C. After cooling to room temperature, the colorant, which has precipitated in orange crystalline platelets, is filtered off, washed with DMF and alcohol and dried at 80°-90°C in vacuo. 194 parts (93.2% of theory) are obtained of 2-phenyl-6-phenylmercaptoanthrapyrimidine, which dyes polyester in bulk in fast, yellow shades.
