Лако-красочные материалы — производство

Since p-nitroaniline does not form water stable salts, the base must be obtained in a highly divided state before the diazotization reaction. A clear solution of 13.8 grams (0.1 mole) of technical p-nitroaniline in 30 cc. concentrated hydrochloric acid and 30 cc. water at 80-90°C. is added with good stirring to a mixture of 50 cc. water and 50 grams of finely crushed ice. The temperature of the final mixture is about 8°. A 20 per cent solution containing 7 grams of sodium nitrite is then added in one portion with vigorous stirring. The temperature rises to 15° and the solution becomes clear in a few seconds. The usual tests with Congo red and starch-iodide are made. In large scale diazotizations, the nitrite solution should be added very rapidly below the surface of the liquid in order to prevent the formation of large amounts of the diazoamino compound.