PREPARATION OF UNIONIC IODINE-CONTAINING X-RAY CONTRAST AGENTS

The preparation method for iohexol(1) used as non-toxic X-ray contrast media comprises (A) synthesizing 5-amino-2,4,6-triiodoisophthalic acid(8) by iodized substitution using ICl made by adding HCl into 5-aminoisophthalic acid(7), (B) preparing 5-acetamido-2,4,6-triiodoisophthaloyl acetic acid anhydride(9) by acetylating the chlorinated (8) with PCl5 with acetic acid anhydride and H2SO4, (C) producing 5-acetamido-2,4,6-triiodo-N,N'-bis(2,3-dihydroxypropyl)-isophthalamide(10) by reacting (9) with aminopropanediol under NaHCO3 catalyst after dissolving it in dioxane water solution, and (D) preparing isohexol(1) by reacting the dissolved (10) in aqueous methanol solution with chloromethyloxysilane under K2CO3 catalyst. The obtained compound is useful for blood vessel irradiation, especially suitable for brain vessel, heart and peripheral vessel because of its non-toxicity.