METHOD OF SYNTHESIS OF 5-AMINOSALICYLIC ACID FOR PHARMACEUTICAL AIMS Russian patent published in 2000 - IPC

FIELD: chemical technology, chemical-pharmaceutical industry, pharmacy. SUBSTANCE: process is carried out by addition of sodium hydrosulfite to an aqueous-alkaline solution of 5-phenylazosalicylic acid at 20-40 C in a single stage, reductive reaction at 80-85 C, separation of aniline at the room temperature in the presence of nonionogenic surface-active substance, purification from residual impurities in the presence of nonionogenic surface-active substance at 60-70 C and pH 5.8-6.2, extraction with benzene and then with coal followed by isolation of the end product by acidification with acetic acid to pH 4.0-5.0. Neonols AF 9-10 and AF 9-12 are used as nonionogenic surface-active substances in the amount 0.4-0.8% of parent 5-phenylazosalicylic acid weight. The yield of 5-aminosalicylic acid is 84.7-86.1% as measures for 5-phenyl-azosalicylic acid. Method provides alternation of conditions of reduction of 5-phenylazosalicylic acid with sodium hydro-sulfite and separation of aniline and impurities from reactive solution after reduction reaction termination. EFFECT: simplified industrial method of synthesis, high yield of product. 2 cl, 1 tbl, 6 ex