| 摘要 |
FIELD: organic chemistry, chemical technology. ^ SUBSTANCE: invention relates to a method for preparing phenylene-bis-benzimidazole-tetrasulfonic acid. Method involves interaction of o-phenylenediamine with terephthalic and chlorosulfonic acid in the presence of strong acids for 10-15 h. Phenylene-bis-benzimidazole-tetrasulfonic acid prepared at the first stage after reaction is dissolved in water and treated with activated carbon followed by removing the latter. Then phenylene-bis-benzimidazole-tetrasulfonic acid disodium salt is precipitated by addition of sodium chloride. At the second stage it is dissolved in water again, treated with activated carbon again followed by removing the latter and pure phenylene-bis-benzimidazole-tetrasulfonic acid disodium salt is precipitated from filtrate by its acidification. If necessary, the prepared salt can be purified additionally. Phenylene-bis-benzimidazole-tetrasulfonic acid disodium salt can be used in cosmetic agents as ultraviolet filter A. Invention provides preparing phenylene-bis-benzimidazole-tetrasulfonic acid disodium salt without impurities. ^ EFFECT: improved preparing method. ^ 7 cl, 1 ex |
